Ferrite Transformer Turns Calculation for High-Frequency/SMPS Inverter On different forums, I often find people asking for help in calculating the required turns for a ferrite transformer they are going to use in high-frequency/SMPS inverters. In a highfrequency/SMPS inverter, the ferrite transformer is used in the step-up/boost stage where the low voltage DC from the battery is stepped up to high voltage DC. In this situation, there are really only two choices when selecting topology – push-pull and full-bridge. For transformer design, the difference between a push-pull and a full-bridge transformer for same voltage and power will be that the push-pull transformer will require a center tap, meaning it will require twice the number of primary turns as the full-bridge transformer. Calculation of required turns is actually quite simple and I’ll explain this here. For explanation, I’ll use an example and go through the calculation process. Let’s say the ferrite transformer will be used in a 250W inverter. The selected topology is pushpull. The power source is a 12V battery. Output voltage of the DC-DC converter stage will be 310V. Switching frequency is 50kHz. The selected core is ETD39. Remember that the output of the transformer will be high frequency AC (50kHz square wave in this case). When I refer to an output of high voltage DC (eg 310VDC mentioned above), this is the DC output obtained after rectification (using ultrafast recovery diodes configured as bridge rectifier) and filtration (using LC filter). During operation, the battery voltage does not stay fixed at 12V. With high loads, the voltage will be less than 12V. With low loads and near-fully charged battery, the voltage may be higher than 13V. So, it must be kept in mind that the input voltage is not constant, but is variable. In inverters, the battery low-cut is usually set at 10.5V. So, we’ll take this as our lowest possible input voltage. Vinmin = 10.5V The formula for calculating the number of required primary turns is:
For our push-pull transformer, this will be one-half the required number of turns. Npri means number of primary turns; Nsec means number of secondary turns; Naux means number of auxiliary turns and so on. But just N (with no subscript) refers to turns ratio.
For calculating the required number of primary turns using the formula, the parameters or variables that need to be considered are:
Vin(nom) – Nominal Input Voltage. We’ll take this as 12V. So, Vin(nom) = 12.
f – The operating switching frequency in Hertz. Since our switching frequency is 50kHz, f = 50000.
Bmax – Maximum flux density in Gauss. If you’re used to using Tesla or milliTesla (T or mT) for flux density, just remember that 1T = 104 Gauss. Bmax really depends on the design and the transformer cores being used. In my designs, I usually take Bmax to be in the range 1300G to 2000G. This will be acceptable for most transformer cores. In this example, let’s start with 1500G. So Bmax = 1500. Remember that too high a Bmax will cause the transformer to saturate. Too low a Bmax will be under utilizing the core.
Ac – Effective Cross-Sectional Area in cm2. You will get this information from the datasheets of the ferrite cores. Ac is also sometimes referred to as Ae. For ETD39, the effective cross-sectional area given in the datasheet/specification sheet (I’m referring to TDK E141. You can download it from here: www.tdk.co.jp/tefe02/e141.pdf ), the effective cross-sectional area (in the specification sheet, it’s referred to as Ae but as I’ve said, it’s the same thing as Ac) is given as 125mm2. That is equal to 1.25cm2. So, Ac = 1.25 for ETD39.
So now, we’ve obtained the values of all required parameters for calculation Npri – the number of required primary turns. Vin(nom) = 12
f = 50000
Plugging these values into the formula:
Bmax = 1500
Ac = 1.25
Npri = 3.2 We won’t be using fractional windings, so we’ll round off Npri to the nearest whole number, in this case, rounded down to 3 turns. Now, before we finalize this and select Npri = 3, we better make sure that Bmax is still within acceptable bounds. As we’ve decreased the number of turns from the calculated figure (down to 3.0 from 3.2), Bmax will increase. We now need to figure out just how much Bmax has increased and if that is still an acceptable value. Vin(nom) = 12
f = 50000
Npri = 3
Ac = 1.25
Bmax = 1600 The new value of Bmax is well within acceptable bounds and so we can proceed with Npri = 3. So, we now know that for the primary, our transformer will require 3 turns + 3 turns. In any design, if you need to adjust the values, you can easily do so. But always remember to check that Bmax is acceptable.
For example, if for construction difficulties, winding 3 turns + 3 turns becomes difficult, you may use 2 turns + 2 turns or 4 turns + 4 turns. Increasing number of turns won’t hurt – you’ll just be under utilizing the core. However, decreasing number of turns increases Bmax, so just recheck to make sure Bmax is okay. The range I’ve stated for Bmax (1300G to 2000G) is just an estimate. It will work for most cores. However, with many cores, you can go higher to decrease the number of turns. Going lower will just be under utilizing the core, but may sometimes be required if number of turns is too low.
I’ve started off with a set Bmax and gone on to calculate Npri from there. You can also assign a value of Npri and then check if Bmax is okay. If not, you can then increase or decrease Npri as required and then check if Bmax is okay, and repeat this process until you get a satisfactory result. For example, you may have set Npri = 2 and calculated Bmax and decided that this was too high. So, you set Npri = 3 and calculated Bmax and decided it was okay. Or you may have started with Npri = 4 and calculated Bmax and decided that it was too low. So, you set Npri = 3 and calculated Bmax and decided it was okay.
Now it’s time to move on to the secondary. The output of our DC-DC converter is 310V. So, the transformer output must be 310V at all input voltages, from all the way up from 13.5V to all the way down to 10.5V. Naturally, feedback will be implemented to keep the output voltage fixed even with line and load variations – changes due to battery voltage change and also due to load change. So, some headroom must be left for feedback to work. So, we’ll design the transformer with secondary rated at 330V. Feedback will just adjust the voltage required by changing the duty cycle of the PWM control signals. Besides feedback, the headroom also compensates for some of the losses in the converter and thus compensates for the voltage drops at different stages – for example, in the MOSFETs, in the transformer itself, in the output rectifiers, output inductor, etc. This means that the output must be capable of supplying 330V with input voltage equal to 10.5V and also input voltage equal to 13.5V. For the PWM controller, we’ll take maximum duty cycle to be 98%. The gap allows for dead-time. At minimum input voltage (when Vin = Vinmin), duty cycle will be maximum. Thus duty cycle will be 98% when Vin = 10.5 = Vinmin. At maximum duty cycle = 98%, voltage to transformer = 0.98 * 10.5V = 10.29V. So, voltage ratio (secondary : primary) = 330V : 10.29V = 32.1 Since voltage ratio (secondary : primary) = 32.1, turns ratio (secondary : primary) must also be 32.1 as turns ratio (secondary : primary) = voltage ratio (secondary : primary). Turns ratio is designated by N. So, in our case, N = 32.1 (I’ve taken N as the ratio secondary : primary). Npri = 3 Nsec = N * Npri = 32.1 * 3 = 96.3 Round off to the nearest whole number. Nsec = 96. Thus 96 turns are required for the secondary. With proper implementation of feedback, a constant 310VDC output will be obtained throughout the entire input voltage range of 10.5V to 13.5V.
Here, one thing to note is that even though I took 98% as the maximum duty cycle, maximum duty cycle in practice will be smaller since our transformer was calculated to provide 330V output. In the circuit, the output will be 310V, so the duty cycle will be even lower. However, the advantage here is that you can be certain that the output will not drop below 330V even with heavy loads since a large enough headroom is provided for feedback to kick in and maintain the output voltage even at high loads. If any auxiliary windings are required, the required turns can be easily calculated. Let me show with an example. Let’s say we need an auxiliary winding to provide 19V. I know that the output 310V will be regulated, whatever the input voltage may be, within the range initially specified (Vinmin to Vinmax – 10.5V to 13.5V). So, the turns ratio for the auxiliary winding can be calculated with respect to the secondary winding. Let’s call this turns ratio (secondary : auxiliary) NA. NA = Nsec / Naux = Vsec / (Vaux + Vd). Vd is the output diode forward drop. Let’s assume that in our application, a schottky rectifier with a Vd = 0.5V is used. So, NA = 310V / 19.5V =15.9 Nsec / Naux = NA Naux = Nsec / NA = 96 / 15.9 = 5.96 Let’s round off Naux to 6 and see what the output voltage is. Vsec / (Vaux + Vd) = NA = Nsec / Naux = 96 / 6 =16.0 (Vaux + Vd) = Vsec / NA = 310V / 16.0 = 19.375V Vaux = 19.375V – 0.5V = 18.875V (rounded off) I would say that’s great for an auxiliary supply. If in your calculations you come to a voltage that is too far off the required target voltage and thus greater accuracy is required, take Vaux as something higher and use a voltage regulator. For example, if in our previous example, instead of18.875V we had gotten 19.8V but needed more accuracy, we could've used 24V or thereabouts and used a voltage regulator to give 19V output. So, there we have it. Our transformer has 3 turns + 3 turns for primary, 96 turns for secondary and 6 turns for auxiliary. Here’s our transformer:
Calculating required number of turns for a transformer is actually a simple task and I hope that I could help you understand how to do this. I hope this tutorial helps you in your ferrite transformer designs. Do let me know your comments and feedback. Posted by Tahmid at 4:23 PM Email ThisBlogThis!Share to TwitterShare to FacebookShare to Pinterest 196 comments:
1. sandyDecember 24, 2012 at 8:30 AM yes thamid it helps me very much,i have a dought generally ferrite transformers required high frequency to drive is 50khz enough to convert 12vdc to 310vdc? one more question home appliances required 230v then y we go for 310v ? Reply Replies
1. AnonymousDecember 28, 2012 at 5:07 AM
310 = 230V RMS Reply
2. TahmidDecember 24, 2012 at 12:14 PM Hi sandy, I'm glad that my tutorial has helped you. 1) 50kHz is enough for use with ferrite transformer. Frequencies between 20kHz and 100kHz are usually used, with 30kHz, 50kHz, 75kHz and 100kHz being common frequencies. 2) I assumed 220V instead of 230V. I was thinking of sine wave inverter. So, to obtain a sine wave with RMS 220V, the peak must be 220V * sqrt(2) = 311V [sqrt(2) means square root 2, which is equal to 1.4142135....]. So, I took 310V since the DC bus voltage will be the peak voltage. When SPWM (sinusoidal pulse width modulation) is carried out, you will receive an output of 220V. If you are interested regarding SPWM, you may go through these: http://tahmidmc.blogspot.com/2011/01/generation-and-implementation-of-sine.html http://tahmidmc.blogspot.com/2012/10/smart-sine-software-to-generate-sine.html http://tahmidmc.blogspot.com/2012/10/generation-of-sine-wave-using-spwm-in_10.html http://tahmidmc.blogspot.com/2012/11/feedback-in-sine-wave-inverter-pic16f.html Hope this helps. Tahmid. Reply
3. sandyDecember 24, 2012 at 11:48 PM yes thamid i have a small request i am trying to develope a 150w inverter with smps transformer ,plz give your mail or send me a mail to this
[email protected] .i will send my circuit diagram to your mail ,plz verify it for my satisfaction. Reply
4. veeraDecember 27, 2012 at 5:59 AM dear tahmid Its really helpful for me I was designing boost converter for my solar home ups. I need help from after reading the following link http://tahmidmc.blogspot.in/2012/09/some-ofmy-smps-circuits.html I was in need of LCR Mere circuit can you post the firmware and circuit. Reply Replies
1. Rupali SdsMay 14, 2013 at 9:28 AM Thanks for sharing this info.Please visit my site also-design of transformer Reply
5. TahmidDecember 27, 2012 at 2:56 PM You can get it if you search on Google. A good design was, I think, the IronBark LC Meter. Do take a look. Reply
6. AnonymousDecember 30, 2012 at 12:50 AM Thanks for your reply...! regards veera Reply
7. Rony ChakrabortyJanuary 8, 2013 at 9:26 AM Dear Thamid I live in Chittagong. I'm also doing Power electronics research. Please contact me at
[email protected], or my website is www.ekushebangla.com Reply 8. TahmidJanuary 8, 2013 at 1:03 PM Hi, If you are interested in contacting me, you can email me at inferno-rage (at) hotmail.com Reply Replies
1. AnonymousNovember 20, 2014 at 2:28 AM Hi Tahmid, It will be good if you post information about EMI filters for Inverters at the input. Reply
9. segarJanuary 20, 2013 at 8:35 AM hi, tahmid the circuits i have see its useful for any fast projects i have idea to build power inverter 6kw out put and input voltage is 48vdc the output voltage is 240vac, but in here i want to use SMPS transformer to built and the power mosfet ,can you help me to have any idea to guide me to help on it ,thanks so keep and touch Reply
10. segarJanuary 20, 2013 at 8:41 AM hi,TAHmid I forgot give you online email, you can directly email me via
[email protected] and also we can share many more on it TAHMID my name is SEGAR. THANKS BYE Reply 11. TahmidJanuary 20, 2013 at 11:11 AM Hi, Use SG3525 to feed into high-low side drivers that drive MOSFETs in full-bridge configuration. These MOSFETs will drive a ferrite transformer. Rectify and filter the output. That's the DC-DC stage done. AC conversion stage will depend on a lot of things, most important being the desired otuput. My hunch is that it's sine wave. So use microcontroller and high-low side drivers to generate SPWM and drive MOSFETs in bridge configuration. Filter the output of the bridge and you have a sine wave output! Reply
12. YtsocJanuary 24, 2013 at 10:40 AM Hello tahmid. I am planning on building a msps for a car amp. The amp requires a single 50v rail and 300watts. I rather design the smps to be able to deliver this power continously rather than applying some music coeficient. So, : 300w , 12v to single 50v (regulated) . My big problem is choosing the transformer core. To be more precise how do i know how much power can a core handle? I know this varies with the frequency but have no idea how to determine it. For example in here:http://www.irf.com/technical-info/refdesigns/iraudps1.pdf they use a 29mm ring core for 500w(or even 1kw if i understood corectly). I have this core witf 3F3 material http://www.farnell.com/datasheets/1595842.pdf
Will this core be able to handle the 300W continously? Also for this core , Bmax should be 100mT? Thank you ! Reply Replies 1. TahmidFebruary 18, 2013 at 7:38 AM How much power a core can handle depends on the core itself and varies from manufacturer to manufacturer. Other factors that affect the power include operating frequency, selected topology, etc. A rough idea can be found in Abraham Pressman's "Switching Power Supply Design" book. I will take a look at the core datasheets you have linked to and let you know more. Regards, Tahmid. Reply
13. AnonymousFebruary 18, 2013 at 7:17 AM hi i really love your tutorials but i would like to ask how i would go about when in comes to winding transformers for switch mode power supplies does the same rule apply and i would also like you to email me a h-bridge inverter circuit i would love to construct one for my final year project my email address is
[email protected] thanks Reply Replies 1. TahmidFebruary 18, 2013 at 7:36 AM
Hi, The tutorial presented here is for switch mode power supplies. I had the push-pull and full-bridge SMPS transformers in mind when designing it. Of course, I had in mind a low voltage to high voltage converter, although the same idea/principle can be applied for high voltage to low voltage converter. As for the H-bridge circuit, I suggest you do some research and design the circuit. If you're stuck somewhere, then I can try to help. Regards, Tahmid. Reply
14. djFebruary 23, 2013 at 2:33 AM how can we calculate b(max)..flux density for E55 core..?? can u please tell me.?input voltage 12 volts dc,output 350 volts dc, Reply Replies 1. TahmidFebruary 23, 2013 at 4:45 PM Choose something between 1300G and 2000G. That shouldn't be a problem. How about starting with 1500G? Regards, Tahmid.
2. Rupali SdsMay 2, 2013 at 5:31 AM such a gr8 blog.please visit my site also.......Potential Transformers Reply
15. djFebruary 23, 2013 at 2:36 AM by using push pull topology Reply
16. djFebruary 24, 2013 at 1:26 AM dude..!!! how do we know that ..specific core has specific gauss?? am using E55 core ..can u tell me how much gauss it will be?? and for e65 core also..?? please tell me how much gauss it will be??reply me soon Reply 17. TahmidFebruary 24, 2013 at 6:07 AM A core doesn't have a specific flux density. You choose what flux density the core is to be "operated". This is done by selecting the number of turns with respect to the applied voltage. A core has a limit up to which the flux density can be. This is usually quite a bit larger than 3000G. So, by selecting an operating max flux density in the range 1300G to 2000G, we're "playing it safe". Regards, Tahmid. Reply Replies
1. Muhammad AbrarDecember 15, 2013 at 1:39 PM Hi Tahmid, i found your articles very informative and helpful. can we use 1300G to 2000G fulx density for 50 or 60 hz transformer if yes then what will be the turns fromula
thanks ragards M.Abrar Reply
18. AnonymousFebruary 28, 2013 at 6:13 AM hi tahmid i have some h-bridge circuits i would like to share with you how can i get it across to you one involves the popular tl494 and the other involves the use of the use of the 556 and cd4013 and another involve the ir2153 chip i would like you to have a look at them and i need a few explanation on some areas my email is
[email protected] thnks. Reply Replies 1. TahmidFebruary 28, 2013 at 11:15 PM Upload the files to a file storage site such as rapidshare and share the links here. Just remember to make the files public. Regards, Tahmid. Reply
19. AnonymousMarch 1, 2013 at 10:57 AM plz tahmid bro tell me calculations for full bridge same as u have explained push-pull here. i seriously need them for my final year project, plz reply me on my email
[email protected] or plz post it on your blog i will vist it sometime later, thanx Reply
Replies 1. TahmidMarch 1, 2013 at 11:50 AM If you go through this tutorial here, you'll see that I've mentioned that the same calculation can be used for push-pull and full-bridge. The only difference will be that, where in a push-pull transformer, the primary consists of Npri + Npri turns, the full-bridge transformer will only have Npri turns for the primary - no center tap. Regards, Tahmid.
2. কককশশক July 31, 2014 at 2:43 AM ভভই সভলভম শনববন, আশম ভভবলভ কবর শকছছ বছশঝ নভ তবব শশখবত কচষভ করশছ আশম আই শপ এস এর টভনফমভর বভবধবত কচষভ করশছ শকন এক এক জভয়গভয় একএকটভ সসত এখন সশঠক ভভবব বছবঝ উঠবত পভরশছ নভ শক ভভবব পভইমভরর ও কসবকনভরর পপভচ ও নভমভর অফ টভনর কবর করববভ আবভর ককভনটভই বভ সশঠক হবব আবভর ককভনটভ কবশঠক হবব। অনছগহ কবর জভনভবল খছবই উপকভর হয়। শপজ শপজ শপজ ...... । Reply 20. Rony ChakrabortyMarch 5, 2013 at 10:20 PM Hi Thamid . Can u please describe How to select a core for a certain power. suppose i need 500w output power, and i also have Ac an Al values form core datasheet, now how to calculate delivered power? Actually it will be very helpful for ur reader if you refer using to relation between area product, winding area and core area, You know what i mean. And thanks for a good artical Reply Replies
1. TahmidMarch 6, 2013 at 7:47 AM Hi, I'll try to write an article on this topic and post it soon. Thanks for the suggestion! Regards, Tahmid. Reply
21. abmMarch 7, 2013 at 1:26 PM Hi Tahmid, please can this calculation work for torroidal cores as well? thanks Reply Replies 1. TahmidMarch 11, 2013 at 12:49 PM It should - just take the appropriate values from the datasheet. Although, I haven't thought of it before. It's intersting and it's good that you brought it up. It should work. But just to be sure, I'll research into it and let you know. In the mean time, you could do some searching too! You might learn something interesting! Regards, Tahmid.
2. abmMarch 21, 2013 at 3:44 PM
thanks tahmid. just another issue, its not easy getting these ferrite transformer here let alone getting the datasheet. i use to try salvaging the ones from computer psu please how can i identify the type of transformer they are e.g etd39 or etd49 and so on. do you have experience with this pleae help out thanks. 3. TahmidMarch 26, 2013 at 5:29 AM Look for the datasheet, eg for ETD39 or ETD49. The number (eg 49 or 39) is dependent on the dimensions of the core. The preceding letters (ETD) denote the "shape" and type of transformer. So, by matching the dimensions of your core against the datasheet figures you can identify which core. Common cores used in computer power supplies are EI33 (most popular) and ERL35. Regards, Tahmid.
4. abmApril 12, 2013 at 9:46 PM thanks, i will sure check them out more. but please do you know where i could get this cores in india. 5. TahmidApril 22, 2013 at 5:42 AM I think you should be able to get them quite easily. I know that Farnell India, which I think is now element14, has quite a lot of them. Regards, Tahmid. Reply
22. AnonymousMarch 11, 2013 at 12:00 PM
hi tamid could you pls check out this h-bridge circuit use this link https://rapidshare.com/files/850668221/ir2153%20fill-bridge.png my email is
[email protected] i would post some later Reply Replies 1. TahmidMarch 11, 2013 at 12:50 PM I'll see and let you know. Regards, Tahmid. Reply
23. starMarch 16, 2013 at 12:50 PM sir plz given me inverter circuit diagram on this transformer....plz sir tahmid needed me inverter circuit diagram of this ferrite core transformer...this transformer of any not found circuit diagram now me..... Reply Replies 1. TahmidMarch 18, 2013 at 12:16 PM You can design the circuit yourself using the SG3525 PWM controller. I've written an article / tutorial regarding using the SG3525: http://tahmidmc.blogspot.com/2013/01/using-sg3525-pwm-controllerexplanation.html Hope you find this helpful.
Regards, Tahmid. Reply
24. starMarch 16, 2013 at 1:00 PM or some circuit diagram received but the diagram in auxiliary winding not found... Reply Replies 1. TahmidMarch 18, 2013 at 12:17 PM The transformer was calculated using an example. You can use the calculation methodology for your own use in your own circuits. Regards, Tahmid.
2. AnonymousMarch 19, 2013 at 11:54 PM hello Tahmid keep the good work going. I am running into a lot of problems that only u can help me. I recalculated my primary turns for 24v transformer in the formular u gave but when I check I am getting nearly two times the secondary voltage i worked it out for Is there anything else to be changed in the formular other than the input nominal voltage from 12 to 24 v when working out the turns for the transformer. Thank u 3. TahmidMarch 21, 2013 at 11:55 AM Recheck the calculations carefully to make sure you've done them correctly.
Make sure you have an LC filter and a minimum load at the output. Don't measure the output voltage without load, feedback or LC filter. With no load, the output capacitor will charge to the peak voltage. Without the load and LC filter, you won't obtain the "averaging" desired and output will be too high. Regards, Tahmid.
4. AnonymousMarch 23, 2013 at 7:48 PM thank you Tahmid for your support I will do as u suggest because i was checking the voltage without load 5. TahmidMarch 26, 2013 at 5:30 AM You're welcome. Do let me know the results. Regards, Tahmid. Reply
25. starMarch 16, 2013 at 1:04 PM sir your answer of waiting....... Reply Replies 1. TahmidMarch 18, 2013 at 12:17 PM
Sorry for the late replies. I was very busy with school exams. Reply
26. starMarch 18, 2013 at 3:22 PM plz tell me... where do u live.....? plz......dont your mind plz......i m only asking..... Reply Replies 1. TahmidMarch 21, 2013 at 11:49 AM I live in Dhaka. What about you? Reply
27. djMarch 19, 2013 at 2:10 AM Hi Tahmid, Thanks for supporting designers, we r working on 1KW inverter with below specs 12v-350v dc-dc converter with pushpull topology e65 core ferrite full bridge topology with igbt for ac-dc inversion we r planning to provide the isolated feedback with a transformer transformer specs are input will be from e65 core transformer and output must be scaled down to 5v dc to connect to sg3525.
plz provide us the details of the transforme like core to be used and no tunrs thanks in advance. Reply Replies 1. TahmidMarch 21, 2013 at 11:50 AM You can calculate the transformer turns if you thoroughly go through this tutorial. All steps have been covered. Regards, Tahmid. Reply
28. starMarch 19, 2013 at 2:30 AM tahmid plz tell me inverter circuit diagram 12v to 220v step up on this trnasformer ferrite core...if you are knowledge.... Reply Replies 1. TahmidMarch 21, 2013 at 11:52 AM Go through this: http://tahmidmc.blogspot.com/2013/01/using-sg3525-pwmcontroller-explanation.html Regards, Tahmid. Reply
29. AnonymousMarch 20, 2013 at 1:24 AM hi tahmid thanks for your formula on calculating the primary and secondary turns for ferrite etd 39 core i understand the nominal voltage in which is 12 the switching frequency 50khz which is 50000 the bmax or flux density you choose to be 1500 and the core area 1.25cm2 to give 330V but i dont know how you arrive at the 10 to the eighth power or the number 4 placed in the formula could you please give an explanation on it because i would truely appreciate it and secondly if i am going to calculate the number of primary and secondary turns for the transformer to work from 24VDC do i just have to put in 24 as the nominal voltage in or there is other things in the formula that will have to be adjusted or changed i truely have high regards for your work time and your answers to our questions thanks again please give an answer at anytime within your convenience thanks Reply Replies 1. TahmidMarch 21, 2013 at 12:08 PM Hi, Thanks for the compliments. The 10^8 term comes due to conversion of the different units to "standard units", ie from cm^2 to m^2 and Gauss to Tesla. You can eliminate the term 10^8 if you use m^2 instead of cm^2 and Tesla instead of Gauss. Remember that 1 m^2 = 10^4 cm^2 and that 1T = 10^4 G . That's where the 10^8 comes from. I hope that clears things up. You can just put in 24VDC there. Nothing else needs to be adjusted. Wishing you success on your project, Tahmid.
2.
AnonymousMarch 24, 2013 at 9:20 PM thanks tahmid i fully understand everything worked on my project and everything is working well but one more thing the 98% duty cycle you choose to calculate the number of secondary turns is it that you must use 98% or you can choose a lower duty cycle and whether the duty cycle is high or low what effect would it have on running home appliances thanks again you are the BOSS 3. TahmidMarch 26, 2013 at 5:32 AM Thanks for the compliments. I chose 98% as a maximum to prevent cross-conduction. In practice it'll be much lower due to feedback. There isn't a benefit to running it low. Instead, you'll need more turns on the transformers. Feel free to ask if you have any further questions/queries. Regards, Tahmid.
4. AnonymousMarch 27, 2013 at 1:01 AM hi tahmid my project has been successful so far but i need to get something clear about "FEEDBACK" i plan to have 288VDC at the output of my dc-dc converter with lc filter, feedback and a minimum load, so from pin 16 to pin 2 of the "SG3525" i put a 5k6 resistor thus voltage at pin 2 is 3.2, from the output of the dc-dc converter i put a 450k resistor to pin 1 and 5k from pin 1 to ground so the voltage at pin 1 and 2 are equal, so 450:5 would give a 90:1 resistance ratio, so 90*3.2 would be 288, NOTE BRIEFLY i am operating from 24VDC i made my calculations for primary turns using the formula, checked b max and everything is in acceptable position i know i need some headroom for "FEEDBACK" to work so i took 98% duty cycle and calculate 0.98*22.5 minimum voltage which gives 22.05, so i calculate my secondary turns by taking 308V:22.05=13.96 so 13.96*7 which is my number of primary turns gives 97.77 rounded off to 98 to be my number of secondary turns do you think my calculations is right? i am looking forward for your reply thanks again in advance and remember you are the BOSS......
5. TahmidMarch 31, 2013 at 1:27 PM If you put a 5k6 resistor from pin 16 to pin 2, with no other resistor from pin 2 to ground, the voltage at pin 2 will be 5V and not 3.2V as you have mentioned. The resistance ratio will be 91:1 and not 90:1 as you have mentioned. Regards, Tahmid. Reply
30. siktecMarch 21, 2013 at 11:51 AM hi Tahmid, how do i determine the current rating of wire for a particular transformer power. Reply Replies 1. TahmidMarch 21, 2013 at 11:56 AM This will depend on the wire itself. You can get charts online. Just Google for wire current rating tables or charts. There are loads available. Regards, Tahmid. Reply
31. AnonymousMarch 22, 2013 at 11:21 PM
Hi Tahmid, about the ferrite transformer above, how about the diameter of wire? whether does not effect with the output voltage? thank you for your advise. BR Heri Reply Replies 1. TahmidMarch 26, 2013 at 5:33 AM Choose the wire such that it can carry the entire current without heating significantly. However, don't use thick wires. They'll suffer due to skin effect. Use multiple thin wires. Take a look at this: http://www.powerstream.com/Wire_Size.htm Regards, Tahmid. Reply
32. AmruthMarch 23, 2013 at 1:09 AM Hi Tahmid, This is an excellent post. Please elaborate on wire sizing, is there any different wiring sizing for high frequency transformers ? Thanks Amruth Reply Replies
1. TahmidMarch 26, 2013 at 5:34 AM Hi, I'll definitely write an article for wire selection. For now, know that you need to choose the wire such that it can carry the entire current without heating significantly. However, don't use thick wires. They'll suffer due to skin effect. Use multiple thin wires. Take a look at this: http://www.powerstream.com/Wire_Size.htm Regards, Tahmid. Reply
33. Udey RajMarch 23, 2013 at 6:16 AM Thanks for sharing it is relevant beneficial information.... Transformer turns ratio meter Reply Replies 1. TahmidMarch 26, 2013 at 5:35 AM I'm glad you found it helpful. Regards, Tahmid. Reply
34. AnonymousMarch 24, 2013 at 9:29 PM the 98% duty cycle you choose when calculating the number of secondary turns could you choose a lower duty cycle and what effect would it have when load is applied to the dc to dc converter Reply Replies 1. TahmidMarch 31, 2013 at 11:15 AM 98% is the maximum duty cycle that I have taken to be allowable. This has been done to prevent cross-conduction between switching devices, which would result in a short-circuit. There isn't much of an advantage to using a lower duty cycle. The actual duty cycle will be much lower than this in normal operation, due to the implementation of feedback. Regards, Tahmid. Reply
35. AnonymousMarch 25, 2013 at 10:54 PM Hi Tahmid I think this is the best pratical inverter building forum on the internet u are teaching the world. I have been trying to put together an inverter over a year now and it since I saw ur blog I am getting some good results.I have three questions 1 with no AC load on my h bridge should i be getting my 5v drive voltage on the gates of the fets in the dc-dc converter I am using one of ur drive circuits ( My voltage only comes on when a load is connected and increase with added load. off when there is no load ) ????? 2 My AC voltage increases with the amount of load I apply eg from 125 to 140v AC which stage could be giving me this problem I am using 556 and 4013 configuration Thank u for ur ususal support Reply
Replies 1. TahmidMarch 26, 2013 at 5:54 AM Thanks man. I hope to add more and make my blog even better. Your ideas and suggestions are welcome. 1) There should always be a load at the H-bridge output. Testing without load can give erroneous readings. Which driver are you using? Can you show the schematic? 2) It could be the drive stage. A circuit diagram will reveal where the problem may lie. Without a diagram, all I'll be doing is guessing. You can upload your schematic to imageshack or photobucket or other such site. Regards, Tahmid.
2. l youngMarch 27, 2013 at 1:55 AM Thank u for your reply Thamid but i am not sure I got A Clear answer. I said I want to know if i should have the drive volt on the gate of the fet any at all with no load connected to the h bridge or only when a load is applied this voltage should come up on the gate. I am using a drive circuit similar to you figure 5 design the only difference is there is no 10k from base to ground on my circuit. Could u answer the other part of the question about the increase in AC voltage with increase load which stage could be giving me that problem . Thank you for usual support 3. TahmidMarch 31, 2013 at 11:13 AM The drive voltage doesn't show properly on the high-side due to the "virtual ground". If you must test it, remove the MOSFETs, connect VS to ground and test the voltage and frequency at HO with respect to ground. If all's well, remove the short from VS to ground and then connect the MOSFETs.
Regarding voltage difference, it'll be difficult to try to figure out where the problem lies without taking a look at the circuit diagram. Make sure that the driver circuit is working properly. It sounds like a problem in the driver circuit, even though nothing can be said with certainty without taking a look at the circuit. I suggest that you, instead of using 556 and 4013, use SG3525. That will be better. Then, just feed the otuput of the SG3525 to the MOSFET high-low side drivers. I hope you have received the answer to your questions. Feel free to ask if you have any query or doubt. Regards, Tahmid. Regards, Tahmid.
4. l youngApril 2, 2013 at 11:12 PM Thank you Thamid for your reply I will check to see my drive circuit is working properly. One more question which design is better to handle heavier loads the paralell or series transformer configuration in the dc to dc converter. Thank you for your support 5. TahmidApril 5, 2013 at 8:58 AM I recommend using one transformer instead of multiple in series/parallel. However, if you must use more than one transformer, you should use the converters in parallel and not the transformers themselves. For example, if you're using push-pull topology and have two transformers, use two push-pull stages to drive both transformers, both from the same input signal. You can connect the outputs in parallel, with current limiting. Regards, Tahmid. Reply
36. saiApril 1, 2013 at 9:38 PM hi tahmid.i am new to this smps stuff.. i have been following all your you-tube posts and blogs on eda board... i am building a 1kw smps inverter according to the circuit diagram you gave in ur link... the only problem is that i am unable to find ft37-77 core.. so could u please help me by suggesting an etd core as an alternative to toroid core and ways to wind it with copper wire...i will be really thankful.. Reply Replies 1. TahmidApril 2, 2013 at 5:51 AM Hi, Could you please mention which link (1kW SMPS inverter) you are talking about? You can choose one of the higher power ETD cores for this purpose. Some cores you may be able to use are ETD49, ETD54, etc. Of course, you need to keep in mind other factors such as winding, frequency, etc. Hope this helps! Regards, Tahmid.
2. saiApril 2, 2013 at 8:47 PM thanks a lot for responding tahmid... i am building a 1kw inverter based on push pull topology for the dc boost stage which is 12v to 32o v dc using ka3525 pwm chip as in ur link.. at 50 khz. initially i thought of using ft37-77 core but later realized i cant find them in here..i know very little about winding an ETD core so i thought if u could help in selecting an ETD and procedure for winding it...thnks again..
3. saiApril 2, 2013 at 9:08 PM here is the link to the circuit diagram http://www.ziddu.com/download/21937039/invertercircuit.png.html 4. TahmidApril 5, 2013 at 9:06 AM I have mentioned some ETD core names in the above post. My antivirus and browser prevent the webpage (where you uploaded the circuit diagram) from loading due to a "suspected web attack". Please upload again or to another file storage site. Regards, Tahmid. Reply
37. AnonymousApril 2, 2013 at 8:48 PM hi again tahmid my project is more successful as i go along, according to your blog on ferrite transformer turns calculation i now have a clear understanding on how to work it out with respect to voltage, frequency, bmax and all that, but there is a few things i want to get more clearly, my questions to you now is, at a switching frequency of 50 khz if i use 22 awg wire to wind the transformer, if i change my switching frequency to 75 khz do i need a smaller wire like about 26 awg to wind the transformer......? next do i have to use a higher switching frequency for a higher wattage inverter or it does not matter as long as the calculations are right...... thanks again for your usual support...... Reply Replies 1. TahmidApril 5, 2013 at 9:01 AM
Yes, as switching frequency increases, you should look to use thinner wire. Refer to this chart: http://www.powerstream.com/Wire_Size.htm You can use a not too high frequency and just make sure that the calculations are correct. Keep in mind that the higher the switching frequency, the lower the required inductance, capacitance and transformer turns, but the higher the switching losses. Hope this helps. Regards, Tahmid.
2. AnonymousApril 5, 2013 at 9:18 PM thanks tahmid all this really helps so to be more clear on all this you are saying its best to use a lower switching frequency for higher wattage inverters and one more thing, i have seen inverters with the transformers in parallel connection and some with the transformers in series connection, which do you think works better.......thanks again for your support...... Reply
38. AnonymousApril 3, 2013 at 7:09 AM hi tamid i designed a 47kz push pull 12v to 310v converter but there is problem i seem to be getting close to 500vdc when rectified i am using an ei33 core ripped from a computer power supply though i have not yet implemented the feedback yet i did all the calculation for the transformer and got 3 + 3 turns for primary and 100 turns for secondary i am wondering if is bcos i winded the primary turns first b4 secondary i chose 1600g as flux pls any help would be appreciated. Reply Replies 1.
TahmidApril 5, 2013 at 9:03 AM You have to use feedback. Without feedback, you'll be running at near 100% duty cycle which will mean very high voltages. Remember that the calculations are done, assuming that proper feedback is in place. The feedback circuitry is to regulate the output voltage depending on input line voltage and output load. The nominal operating duty cycle with correct feedback implementation will be quite a bit lower than 100%. Hope this helps. Regards, Tahmid.
2. L YoungApril 11, 2013 at 8:04 PM Hello Tahmid I have attached the inverter circuit to an email and sent it to ur email address. This is the circuit I am having the gate voltage problem with.Please check to see if there is a circuit error. Thank you Reply
39. herisetiawanApril 9, 2013 at 12:02 AM Hi Tahmid, i have ferrite core Type E55/28/28 http://www.ferroxcube.com/prod/assets/ecores.htm with Ae 420mm2 = 4.20cm2 my question is : 1. i use TL394 for produce 38kHz for drive the push pull. what the problem if i applied this transformer use push pull with frequency 38 kHz ? 2. can i produce 1500 Watt spms use this transformer at 38 kHz push pull? 3. what a good frequency for this application ? Thnks Regards Heri Reply
Replies 1. TahmidMay 2, 2013 at 5:44 AM 1) You can very easily use 38kHz. No problems. 2) I think you should increase the frequency. 3) I would say 50kHz to 75kHz. Make sure you use good MOSFET drivers / driver circuits. Regards, Tahmid. Reply
40. Luminous Inverter DelhiApril 11, 2013 at 6:33 AM Dear Sir, Thanks for your valuble information about Ferrite Transformer you can give great help about transformer. Luminous Inverter Reply Replies 1. TahmidJune 22, 2013 at 9:42 AM I'm extremely glad that you've found my blog helpful! Regards, Tahmid. Reply
41.
AnonymousApril 14, 2013 at 2:50 PM hi tahmid your blog has helped me out the most sucessful way, i have now managed to build a inverter using four dc-dc converters in parallel supplying 310vdc, could u point me to a h bridge circiut that i could build with eight mosfets so i could get 230vac, i really need this and thanks much again Reply Replies 1. TahmidApril 21, 2013 at 9:10 AM I am extremely glad that my blog has helped you. I hope to make my blog even better to reach out to help many more people like you. For the PWM controller, you can use SG3525. Set the frequency to 50Hz/60Hz as required. I've written a tutorial covering the use of the popular PWM controller SG3525. Check it out here: http://tahmidmc.blogspot.com/2013/01/using-sg3525-pwm-controllerexplanation.html For the MOSFET driver, you can use IR2110. I've written a tutorial covering the use of IR2110 for MOSFET drive in high-low side configurations (bridge configurations included). Check it out here: http://tahmidmc.blogspot.com/2013/01/using-high-low-side-driver-ir2110with.html Hope this helps! Regards, Tahmid. Reply
42. AnonymousApril 14, 2013 at 5:25 PM
hi again sir, is there any difference with the h bridge in a 12 volt inverter than that of a 24 volt or its just a standard circuit or the h bridge circuit is built according to the wattage of the inverter thanks........ Reply Replies 1. TahmidApril 21, 2013 at 9:06 AM No matter what voltage you use, the principle is obviously the same. 24V is preferred over 12V for higher powers due to the lower current (for the same power output). This makes component selection and even wire selection easier and due to the lower current, places less "stress" on the components as they need to handle half the current. Regards, Tahmid. Reply
43. AnonymousApril 15, 2013 at 8:10 AM hi tamid here is a funny senario i built a 12v-310v dc-dc converter using an e-i33 core the funny thing here is when i read the ac output section with my meter it shows250v but when i read the dc section its giving me 500vdc is that the recovery diodes are recovering too fast or what ithe diodes i am using is mur460 pls if you have any solution it would be helpful thnks Reply Replies 1. TahmidApril 21, 2013 at 9:13 AM Since your output is DC (you're using a DC-DC converter), you should be using the DC section of the voltmeter. The AC section will give you incorrect reading.
It sounds like you're measuring the output voltage with no feedback in place and with no load in place. Place a sufficient load and use a feedback circuitry and then test again. Regards, Tahmid. Reply
44. jagadeshApril 16, 2013 at 10:48 AM hi tamid i wound a transformer with with 1 primary turn and 3 sec turns for a push pull. my bm is 2230 for 20khz 6 volt input 3.35cm2 core area. but i dont get any output at transformer can u plz help me Reply Replies 1. TahmidApril 21, 2013 at 10:11 AM How are you driving the transformer? What is the switching device you are using? Where do the drive signals come from? Your answering these questions will shed more light on the problem. Regards, Tahmid. Reply
45. AnonymousApril 17, 2013 at 8:43 AM hi tamid do pls know how to manually calculate the area of an etd core ,well since where i live it difficult to buy one so i usually come across so many core but with no labeling so i don't know the core type or its area if you any solutions it would be helpful thnks
Reply Replies 1. TahmidApril 21, 2013 at 9:04 AM You can measure the dimensions of the core and match the values against the values of a standard datasheet to identify which core you have. That way, you can identify the core without needing to have labelling provided to you by your ferrite core supplier. Regards, Tahmid. Reply
46. okofisheApril 21, 2013 at 7:27 AM when you say 3 turns + 3 turns,that is a number of 6 turns in the primary with 2 wires sticking out or what?please explain Reply Replies 1. TahmidApril 28, 2013 at 11:43 AM The transformer has a total of 6 turns primary, with a center tap. You take a wire. Join one end to one of the bobbin pins - A. Then wind three turns and join the other end to another bobbin pin - B. Take another piece of wire and join one end to the end B. In the same direction (clockwise/anticlockwise) in which you wound the first three turns, wind three more turns. Then attach the other end of the wire to another bobbin pin - C. A is one end that goes to a MOSFET "leg". B is the center tap that goes to the positive supply (since this is for a push-pull converter). C is the other end that goes to another MOSFET "leg". Hope this helps.
Regards, Tahmid. Reply
47. AnonymousApril 22, 2013 at 7:47 PM hi tahmid thumbs up again for your blog, i need some help on selecting some mosfets for my dc-dc converter for a 600 watts inverter ( push pull topology } i use two irfz46n to drive my ferrite transformer but they heat and blow out in a short while...... the irfz46n is rated 50 amps so do i have to add more in parallel to my converter or do i need to purchase mosfets rated at higher amps for example irf3205 which is rated 110 amps and how much should i use, PLEASE i need your help or do you have a way to calculate and parallel mosfets to add up to a certain AMP for 600 WATTS ? PLEASE give me your most clear answer on this and keep up the good work thanks again BOSS ...... Reply Replies 1. TahmidMay 2, 2013 at 5:49 AM How much load did you have at the output when the MOSFETs blew? Which PWM controller are you using? Describe the MOSFET drivers you are using. Regards, Tahmid. Reply
48. AnonymousApril 22, 2013 at 8:51 PM
hi again tahmid thanks for your continued help my question to you is, i have a ferrite torodial core the effective cross sectional area in cm2 is 0.946 could i use it in the formula for my transformer calculations....thanks again Reply Replies 1. TahmidApril 28, 2013 at 11:53 AM Yes, you should be able to plug it in the formula for the calculation. Regards, Tahmid. Reply
49. AnonymousApril 24, 2013 at 10:19 AM hi tamid in your replies on me getting about 500v dc you said i should place a load on the output and then implement feedback the question is how do i place a load on a 310vdc output and what kind of load are you talking about coz i dont have a load that will take such voltage i am buliding a small inverter and hope to build the circuit in sections thnks Reply Replies 1. TahmidApril 28, 2013 at 11:35 AM Place any load that draws a current resulting in an output power of greater than minimum required power. You can use 2 light bulbs in series. You might use 2 60W or 100W incandescent bulbs in series. When you don't have sufficient load at the output, the voltage rises to the peak voltage as the capacitor charges to the peak voltage. Peak voltage in your cases seems to be 500V.
Regards, Tahmid. Reply
50. Rupali SdsApril 29, 2013 at 6:44 AM This is very useful blog.This blog is useful for construction.Thanks for sharing this blog.transformer suppliers Reply Replies 1. TahmidMay 2, 2013 at 5:46 AM I'm extremely glad to hear that you've found the blog useful. Feel free to share any suggestions you may have. Regards, Tahmid. Reply
51. herisetiawanMay 1, 2013 at 11:19 PM Hi Tahmid, i have ferrite core Type E55/28/25 http://www.ferroxcube.com/prod/assets/ecores.htm with Ae 420mm2 = 4.20cm2 my question is : 1. i use TL394 for produce 38kHz for drive the push pull. whether any problem if i applied this transformer use push pull with frequency 38 kHz ? 2. can i produce 1500 Watt spms use this transformer at 38 kHz push pull? 3. what a good frequency for this application ?
thank you very much. Regards Heri Reply Replies 1. TahmidMay 2, 2013 at 5:44 AM 1) You can very easily use 38kHz. No problems. 2) I think you should increase the frequency. 3) I would say 50kHz to 75kHz. Make sure you use good MOSFET drivers / driver circuits. Regards, Tahmid. Reply
52. AnonymousMay 4, 2013 at 11:36 AM hi tamid in terms of feedback implementation how do i calculate my duty cycle for instance using the sg3535 setting pin 2 to 2.5v as reference how do i calculate the resistor values for pin 1 for a lets say 90% duty cycle since these pins are responsible for the duty cycle thnks Reply Replies 1. TahmidMay 17, 2013 at 10:29 AM You will get your answer here if you go through it thoroughly: http://tahmidmc.blogspot.com/2013/01/using-sg3525-pwm-controller-
explanation.html Regards, Tahmid. Reply
53. SanjayMay 17, 2013 at 1:08 AM hi sir, i red ur blog and lot of info in ur blog to me, thank for u. my question is : my project's primary turns are 4, i turn on my project but switching mosfet are shortcircuit , plz help me.... Reply Replies 1. TahmidMay 17, 2013 at 10:33 AM That could be due to a lot of things. Without more information, it would be too difficult to understand what's causing the error. Which controller are you using? Which driver are you using? Which topology are you using? Describe the feedback circuitry you're using. What are the input and output specifications? What frequency did you use? What did you select as the maximum duty cycle? Which MOSFETs are you using? Describe the transformer output section. Which transformer core are you using? What is your load? Your answering the above will help shed more light on to the problem. Regards, Tahmid.
Reply
54. bretMay 17, 2013 at 2:50 PM hi Tamid, I,m bret from nigeria.. i really found your blog very useful since i discovered it. keep the good work. Pls i want you to tell me how to do the transformer turn calculation for an smps charger using the half bridge topology. my chager is to handle about 30Amps and 13.8V output frm 220Vac input. Reply Replies 1. TahmidJune 22, 2013 at 9:43 AM Take a look here: http://tahmidmc.blogspot.com/2013/02/ferrite-transformer-turnscalculation_22.html I'm sure you'll get your answer there! Regards, Tahmid. Reply
55. Trent PalmerJune 10, 2013 at 12:05 AM Hello, The airticle "Ferrite Transformer Turns Calculation for High-Frequency/SMPS Inverter " is out standing.I found so many entertaining stuff in your blog.Thanks DC to AC power inverter Reply Replies
1. TahmidJune 22, 2013 at 9:41 AM I'm glad you've found it helpful! Regards, Tahmid. Reply
56. AnonymousJune 23, 2013 at 9:54 AM Hello Tahmid, Your Transformer calculation post has help me a lot in designing DC-DC converter but recently I moved to DC_AC inverter. I can use the method you post here for my high frequency low voltage DC to High voltage DC (20-400 VDC)tranformer design which works very well, also for the 400v DC side filter inductor design I used the methods in Abraham pressman book and my filter works well, BUT I am having problems with my SPWM wave input to Sine Wave output filter inductor. I am not sure if I should use the same method of low pass filter inductor core design method used in DC filtering or is there any special consideration you have to take into account in design of magnetic material for SPWM filter inductor (for pure sine wave output). Sorry for the long wind post. Your help will be greatly appreciated. Faruq Nigeria Reply Replies 1. TahmidAugust 11, 2013 at 3:04 AM For LC filter, choose values such that the resonant frequency is close to your output frequency. If your frequency is 50Hz, an LC filter with resonant frequency between 400Hz to 1500Hz should work well. Then you need to size the inductor and capacitor. Don't use too high an inductance - otherwise the output impedance will be very high. Don't use too high a capacitance - this will create rush currents.
Regards, Tahmid. Reply
57. AnonymousJune 26, 2013 at 3:37 PM Hello Thamid, I have a question about the equation to calculate an output inductor for a forward converter with a transformer (full bridge). I actually have several formulas and all of them are no the same. Which way do you use to calculate it? Reply Replies 1. TahmidJuly 20, 2013 at 4:14 PM Take a look at this: http://tahmidmc.blogspot.com/2013/03/output-inductance-calculation-forsmps.html I think you should find that helpful. Regards, Tahmid. Reply
58. Nilesh S.VadharJuly 30, 2013 at 3:39 AM Nice post about SMPS transformers thanks for sharing nice information. We are also Manufacturer & Supplier SMPS transformer in India Reply
59. AnonymousAugust 4, 2013 at 6:17 PM Bro i want to design push pull invertor . plz help me to design transformer. input DC 4045 V, output 330-340 V and 500 W . what turn ratio of transformer required . Reply Replies 1. TahmidAugust 7, 2013 at 12:21 AM Did you go through the entire tutorial? Everything is covered in this article. Please read it carefully and then ask me if you have any specific questions. Regards, Tahmid. Reply
60. AnonymousAugust 10, 2013 at 2:43 AM Dear, I want to design transformer for 240V to 500V Input of AC supply and Output is 3.5V DC with 200mA . Pls suggest design guideline. ?? Reply Replies 1. TahmidAugust 17, 2013 at 12:41 AM
What kind of transformer are you designing? Are you using SMPS? What topology? 2. Johan SagaertDecember 14, 2013 at 10:27 AM Hi, Tahmid Do you still check your hotmail mailbox from time to time , i would like some advice on winding high voltage secondaries. From what i saw in microwave smps, they seem to wind sections side by side instead of 1 layer over the other. Reply
61. AnonymousAugust 10, 2013 at 3:53 AM Hi Tahmid!!! Very nice tutorials you have put up here, very informative. Tahmid, need clarification on something. Firstly, there is no guide on the internet that shows how to wind a ferrite toroid, yes? Reason is, I`m trying to wind one, and then to test it out. Say my calculations state 5 turns primary, so that means two wires on the primary side, with the center two, linking them, serving as CT, yes? Lastly, the secondary and primary is wound the in the same direction? Or can one just wound this bifilar style for primary, over the many turns of secondary? In my circuit I need a step up. Reply
62. TransformerAugust 16, 2013 at 2:23 PM
There is a big credit of transformer for getting us current constantly. We cannot think about current without transformer. So it is better to know about transformer for every people. Thanks for sharing the information of transformer. Reply 63. suki leeAugust 22, 2013 at 7:08 AM excellent blog about Inverter Manufacturing.keep on posting Inverter Manufacturer Reply
64. TDAugust 28, 2013 at 1:22 AM hi tahmid i have 2 qustion 1st is i make like you tarnsformer it work fine but it out 330v dc how i convert this to 230v 50hz sine wave Ac voltage ? 2nd is i make transformer to 12v-24v to 330v Vin min = 9v , Vin (nom) = 24v and it connect to 12v and out has a 40w bulb transformer sound like "trrrrr" why it is sound like trrrrr please help me Reply
65. tecmaxSeptember 2, 2013 at 7:59 AM The voltage transformers are used in case of voltage fluctuations. You can confer the rigth flow of electricity to the electrical appliances inside your home and save the same from damages. Automatic Voltage Stabilizer Manufacturers, Servo Stabilizer Manufacturers, Isolation Transformer Manufacturers Reply
66. AnonymousOctober 1, 2013 at 11:16 AM Hi really excellent blog, thank you very very much that you are willing to share your knowledge, not many do ! Here is a question, if I want to center tap the secondary to 96 + 96 turns, does the formulation change on the primary side to get the same output as with 1 secondary winding? Or will the 2 secondaries just divided the output power between them. Thanks for the reply :) Reply 67. ananth deepakOctober 8, 2013 at 3:29 AM hello sir,i need to convert dc input range of 80v to 150v,and frequency range 160khz to 200khz,using e65 core,to 230v in ac,and power of 1kw,plz help me Reply
68. bareeza powerOctober 13, 2013 at 4:58 PM thank you this information was very helpful to me i'm designing smps to convert from 12vdc to 220vac 50hz I'm wondering about what are the stages I should follow with arrangement using also I don't know how to calculate the suitable frequency for the circuit what is the most important element of the power supply I should choose first Reply 69.
Alaap JagdaleOctober 20, 2013 at 12:30 PM hello tahmid sir. please solve my doubt how to calculate the gauge of the wire for your above given example of 3+3 turns & 96 turns xmer 50khz. can we apply P=VI & V=I(R+jXl) to find max ampere and accordingly the gauge or due to skin effect @ 50khz its better to use litz wire and if yes than of how many core wd respect to max current. Reply
70. llan perezNovember 6, 2013 at 2:16 PM hola mi pregunta es como se comporta una bobina bifilar en un transformador de ferrita tipo E, yo le inyecto un voltaje de 24vcc a 10khz, sin conectarlo de manera tradicional, si no en serie con la carga, en este caso una celda tipo condensador de 1000uf Reply
71. AnonymousNovember 22, 2013 at 12:10 PM Hi, I made my transformer with 8 primary and 100 secondary turn 33KHz ETD29 (76mm^2) with 11V input. I get 10-15times more voltage while testing signal generator. However when I use the voltage (11V) coming from FET (bf245) I see 200mV on the output.what is the reason for that ? any help is appreciated Reply
72. fmtechDecember 5, 2013 at 7:35 AM
hi, Tahmid, pls can u help me with the code or connection for pic 16f72 sine-wave inverter to enable me make use of the normal off / on switch not the soft push reset type, thanks fmtech83 @yahoo.com. Reply
73. Distribution transformerDecember 6, 2013 at 6:20 AM Hi this is really very helpful article. I go through this site really very nice information.thank for sharing such a nice information. Reply 74. Vasu DevanDecember 15, 2013 at 7:51 AM Dear Tahmid Nice to see ur blog. I am an electronics engineer working in thyristor based high current rectifiers. I am planning for design a high frequency rectifier for high current ranges with bridge rectifier construction. can u please guide me and help to design the same. My questions are 1. for low voltage high current DC output bridge rectifier is suitable?? 2. Can i follow your calculation for this rectifier?? 3. what is the maximum current i can get from high frequency rectifier?? 4. Any book which guide me for designing this system?? thanks vasu Reply
75. AnonymousJanuary 6, 2014 at 10:23 AM Hi tahmid U r amasing pls i need ur assintance on how to calculte Ac or Ae of a ferrite
transformer.how do I make d calclation for: I have aaa ferrite core transformer with dis diamension 42mm*43mm*15mm. (Transformer) how d i calculate Ac or Ae Reply 76. Zeebee RJanuary 15, 2014 at 1:54 AM This comment has been removed by a blog administrator. Reply
77. CarliJanuary 28, 2014 at 11:58 PM Hi Tahmid, I have calculated a transformer for a Push-Pull SMPS that works with 12Vdc and the output is 410V. It has 2+2 turns in the primary and 56+56 in the secondary, with a EE4215 core. In my country I can´t found a company that make that transformer, Did you ever wound a transformer like this? Any suggestion? Thanks you very much and congratulations for your blog that is very useful. Reply 78. usama ja'afarJanuary 29, 2014 at 12:24 PM Hi tahmid! thanks a million for all your efforts. Just got a question to ask: does the same principle apply to toroidal transformer(in smps). If no, then how do we calculate the relationship between input and output voltage?...pls assist. thanks Reply
79. tecmaxFebruary 4, 2014 at 4:17 AM The isolation transformers are essentially devices that are used for the reduction of the power surges. The safety and security of the devices can be accomplished by the installation of the devices. Reply 80. sergulen yenidoganMarch 21, 2014 at 7:20 PM how do you determine the b max value? there is not such a value on the datasheets. Reply 81. Wasim AhmedMarch 28, 2014 at 6:02 AM hi dear can u share more article on this so that i can get more information on calculation transformer losses Reply
82. Nyza ShareefMarch 28, 2014 at 8:28 AM Hi very nice post. Very useful information regarding isolation transformer and its uses. Thanks for sharing this useful blog. Reply
83.
niranjan tiadiApril 3, 2014 at 7:24 AM if i use primary of 21 turns and secondary of 3 turns and suppling 344volts dc then what voltage, current and frequency will i get in secondary using ferrite core u type transformer. Reply
84. Runthala JaipurApril 10, 2014 at 5:48 AM Many companies producing Power transformers in India. Power transformers that will establish the service dependably with the web page, Cost-efficient along with secure through the entire ages. Reply 85. Pedro CockwellApril 15, 2014 at 4:17 AM how to calculate the seccion of de windings gracias Reply
86. Boguslaw BrandysApril 21, 2014 at 11:08 AM This comment has been removed by the author. Reply 87. Vathi rajanApril 26, 2014 at 7:37 AM Nice post about Power Transformers thanks for sharing nice information. We are Power Transformers Manufacturer & Exporters in India
Reply
88. Piyush JhaApril 30, 2014 at 4:29 AM hi can you tell me what should i understand from the ferrite transformer symbol given as below 1 ) (.10 4.) (8 i want to indicate here primary and secondary side by using )( . it is 2 w transformer and output is 7.5v please tell me what is meaning of 1, 4, and 10,8 here . Reply
89. Rahees CMay 4, 2014 at 10:47 PM Hi Thahmid, Hope you are fine. Your blog is really helpful for me. I learned more from you. Now I am planning to design a Transformer-less Inverter using SG3525 in DC-DC and a PIC – PWM module for Sine wave production. I will be following your example circuit you mentioned with SG3525 for DC-DC conversion, but let me know what should be the wire gauge for the DC-DC converter transformer windings to make an inverter of 800W capacity. Please help me on this. Also please suggest isolation for the feedback in the circuit. I am afraid of 320V DC come out the inverter thru battery terminals. Reply 90. HkhurramMay 27, 2014 at 8:45 AM Hi Thahmid, i have a power supply (180W DC12V 15A LED Single Output Switching Power Supply), i took this supply from junk yard for some experiment, i wound transformer as it is i opened but when i ON this supply is going heat too much but output voltage is ok then i put some load on it on series circuit on main, series lamp is ON and output is block, all
components is ok FET is 7N60. ***i want to wind this transformer can u help me***** supply picture is http://www.4shared.com/download/bKbmAVCUce/PH_316.jpg? lgfp=1000 Reply
91. Pravin MagiyaMay 31, 2014 at 1:01 AM how do you wind this transformer. is it 3+3 first and 100 turns or is it the other way Reply
92. Pravin MagiyaMay 31, 2014 at 1:04 AM i have an ee42 core but i cant determine the bmax for it. can you tell me what is its value Reply 93. Sohil SutharJune 7, 2014 at 8:41 AM i want to built power supply of 24Vdc input & 400Vdc output. is there any reference design you have. please guide me. Reply
94. AnonymousJune 16, 2014 at 4:00 AM Hi tahmid i was designing a ferrite core transformer using push pull topology, 60KHz,primary turns-3,sec-turns-120. I generated my signal from SG3525 and IR2110.I pulled down the gate of the mosfets(IRF3205) with 1k resistor but still i am constantly having the mosfets burnt 5minutes after i connected it to the transformer although i did not implement feedback for now. what exactly do think could cause the problem. please help me out this mess.
Reply 95. yılmaz kemancıJuly 21, 2014 at 1:41 PM Tahmid Hi, firstly I congratulate you for doing such a nice sharing sg3525 What is the formula of compensation capacitors, for example, you're using 10nF, other examples 220pF, 47nF, 100nF .... these values are chosen according to what? thanks yılmaz kemancı I love sharing,,, my site http://picsimulatorideexample.wordpress.com/ Reply
96. power transformer philippinesJuly 21, 2014 at 9:33 PM I think you are very expert for transformer ^^ Reply
97. AnonymousAugust 7, 2014 at 5:42 PM Hello Tahmid! good blog, sounds lots of work behind... I'm working on a small inverter 200w. push pull bridge can feed 10Amps. But with no load i can reach 300-400Vac @60Khz. But I can't keep this voltage when a load is plugged i just can reach 60vac @ 30W...... My core is 2+2 primary 60 secondary. Could you tell me what kind of things can be responsible of this loss of power? i feed 8A@12VDC primary and i can just get merely 30W.... primary winding is 3X0.5mm² in parallel. Best regards. B.H@FRA Reply 98. Srini VasanAugust 20, 2014 at 9:25 AM
sir I need 12 v to 110v dc converter and pri/sec winding details and the inductance value of the transformer wattage is 300w Reply
99. AnonymousSeptember 9, 2014 at 7:39 PM impresionant dear, but now i got a question for you... Wich are the best ferrite to get 150W at 3Mhz? Reply
100. AnonymousSeptember 16, 2014 at 8:34 AM helo dear. i need to know how can we decide the current carrying capacity of primary and secondary.please if u dont want to answer, let me know. i asked u this before but u dont answer. ejaz abidi Reply 101. ahmed elbannaSeptember 17, 2014 at 5:12 PM hii Tahmid! im so proud of your info , your so good and helpfull thanks for all of your info 1- i need to know which AWG wire in prim and sec wendings i can use to have output power 1000 watts ,(same core u used) 2- can i turn couple or triple wires together to have higher current in prim turns (3 wires together 3 turns then another 3 for the other 3 turns) 3- what to do with the sec. turns should i triple the wires as in the prim. ? im still confused because i read all ur comments but didnt find what can help , so i'll be so happy to know what i can do to get 1000 watt from the same core u used thanks alot Tahmid :)
Reply 102. sigit kurniawanOctober 12, 2014 at 10:36 PM hi tahmid.. i want to create pontential transformer for voltage measurement, with turn ratio of voltage in transformer...i choose ferrit core because my objeck have frequency in 40 kHz, am i can be used this technique for solving my problems? Reply 103. Kutlu ZungurOctober 14, 2014 at 10:32 AM Thanks in advance for the explanation but why did you divide the fromula by 4.Where does this 4 come from? Best regards, Kutlu Reply
104. power transformer philippinesOctober 23, 2014 at 7:09 PM Thank you for explaining it very well. Keep it up! Reply
105. Path FinderOctober 27, 2014 at 11:31 PM Dear Tahmid, I am new in SMPS design.I want make simple adjustable SMPS labrotory power supply 1-30 volt and max 3 ampere Ebay have very cheap LM2596 or LM2576 Modules. is it possiable a pre simple circuit for working 220 volt AC for this module.I mean it must cheap and small and suitable but it must without power transformer thanks for reply
Regards Serhat Reply 106. Md . Abdur Rahman OwahidNovember 12, 2014 at 7:59 PM Assala-mu-alaikum vai, I've a question about this article. Here you showed 3+3 centre tap primary and 96 turns secondery. If I need 3+3 centre tap primary and secondery also with centre tap than which modification required? Actually this question comes to see this two articles :http://homemadecircuitsandschematics.blogspot.com/2012/09/making-200-wattcompact-pwm-inverter.html and http://easy-electronic-circuits.blogspot.com/2014/05/100-watt-compact-ferriteinverter.html Reply
107. omarx646March 16, 2015 at 2:34 PM Dear sir nice post I have a doubt about the winding primary formule that gives 3.2. turns. in case 3.5, 3.6, 3.9 what should I do? I need to know what to do with that number before calculate secundary winding. Reply
108. AnonymousApril 1, 2015 at 12:36 PM Sir thank you for your tutorial on ferite transformer .my question is if a my ferite core transformer core (ETD44) is broken can it be used still if i glue it back together Reply Replies
1. TroubleshooterJuly 24, 2015 at 11:33 AM It can work as long as it remains complete after the breakage. If you loose even a small portion of the ferrite core, your whole inductance values will change and most likely the over-all behavior of your coupled inductor as well. Reply
109. AkshadeepApril 5, 2015 at 3:42 PM Hi I am using a E25*20*7 Ferrite core. The primary is 12 turns of 22 SWG. The secondary is 320 turns of 36 SWG. I would like to get 300-320 volts. I am using UC3843 and 50 khz frequency. But the output voltage is only 180 voltsWhat needs to be done Reply
110. jtraoApril 7, 2015 at 3:47 PM Hi Akshadeep! What is your input voltage and topology ? is 180V output is with load? do you have feedback control? Tirumala Rao Reply Replies
1. AkshadeepApril 10, 2015 at 3:09 AM Hi Jtrao, Ifyou could provide me your email Id I will email you the schematics. Reply
111. Rodrigo TechiApril 8, 2015 at 7:45 AM hi Tahmid, i'm projecting a high frequency ferrite core, but how do i chose the core, and what range is acceptable for the Bmax? Reply
112. Zeeshan AhmedApril 20, 2015 at 11:01 AM can i use ETD44 Instead of ETD39 ? Reply Replies
1. AnonymousJuly 10, 2015 at 6:03 PM Yes but you must change Ac. Reply 113. Sahadat JonyJune 9, 2015 at 12:31 AM Dear Tahmid vai, I have to need a calculation of 300W toroidal auto transformer.Can u please help me. Reply
114. ursulajudith19July 2, 2015 at 11:44 PM
how can I boost the current of a solar power laptop charger circuit using an Sg and a ferrite core transformer Reply
115. AnonymousJuly 10, 2015 at 6:02 PM Hi Tahmid, I need only 20mA to 80V to drive some leds. The formula is the same or change? Vin*10^8 remain the same or change? Please answer. Thank you in advance! Reply
116. parthiban kandasamyJuly 26, 2015 at 3:29 AM This comment has been removed by the author. Reply
117. parthiban kandasamyJuly 26, 2015 at 3:31 AM Hi tahmid your work so great-full. I recently planned to develop ups for my home. i learned concept ups from your post(MOSFET, Switching) and i have doubt in transformer selection, but you cleared well. One more request is to know about which types of transformer in push-pull stage and output stage as well as its different types and configuration Reply
118. AnonymousJuly 27, 2015 at 12:49 PM
Hi Tahmid, Good work with you tutoring. Your explanations are very will done and easy to understand. I am trying to drive a high power ceramic transducer element using one of the latest TI class D chips. It is the TPA3116D2. This chip allows you to set the PWM frequency between 400 kHz and 1.6 MHz. With that in mind, The core size should get quite a bit smaller. Using the equation in this blog, the cross section becomes very small i.e. .2 cm 2. Any larger a cross section I get 1 turn or less for the primary. The TI part will allow PBTL connection providing up to 100 watts output power. My problem is making sure the impedance never falls below 1.6 ohms. The baseband signal is 25kHz but the PWM frequency can be greater than 400 kHz. The reactance of the ceramic element is tuned out by using a parallel inductor. My question is, do you have any suggestions for the core and the kind of material. I assume the material should be suitable for operation above 400 kHz. I am trying to make the driver amplifier as small as possible and thus I need the smallest core that can handle the power but also present the reflected impedance greater than perhaps 2 ohms. This application is just a variation of a SMPS but at higher frequencies than the 50 kHz circuits posted here. Thanks, Reply
119. AnonymousAugust 4, 2015 at 10:08 AM Hi Tahmid, Thank you for the detailed explanation of HF transformer calculations. But I would like to build LF (low frequency) inverter 1kW using full bridge & SPWM control signals with app. 24kHz to obtain 50Hz 220VAC output. The problem is how to calculate the 50Hz transformer (EI iron core). I am going to use 12V battery but the available information I can find concerns LF inverter transformers but with higher input voltages (24V.... 48V). The recomendation is: - for 48V DC system to use transformer with primary 24-30V Following that recommendation I can calculate the primary for 12VDC system transformer to be app. 6 to 7,5V? Please if you can to advise me how to calculate the needed transformer (EI or toroidal). It
should maintain 220V all the way from 10,5-14V DC (the inverter has feedback line which regulates the SPWM duty). Thanks in advance for support.
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120. smithlarryAugust 14, 2015 at 1:17 AM Shop 12v Converter Inverter at Dctodcpower.com. The 12v inverter basically produces the same type of power that is created by utility companies and generators. When we have the confidence on the high quality of our products, we could offer very competitive prices at the same time.
