Sy Variable Speed Pump Drives for Industrial Machinery – System Considerations
Jan Komsta, Ph.D. Bosch Rexroth 11.19.2013 Chicago
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11.19.2013 | DCUS SET | © Bosch Rexroth AG 2013. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.
Variable Speed Pump Drives for Industrial Machinery
Why speed variable pumps? Reduced energy consumption Reduced average noise Compact power unit Reduced cooling requirements for oil High robustness Intelligent hydraulic drive
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Energy and the Environment – Current Challenges
Policy assumptions for 2020* USA
European Union
Russia
China
India
Brazil
23%** 20 % 15 % 40 % 20 % 36 % share
reduction
reduction
reduction
reduction
reduction
of renewables in electricity generation
in greenhouse gas emissions compared with 1990
in greenhouse gas emissions compared with 1990
in CO2 intensity compared with 2005
in CO2 intensity compared with 2005
in greenhouse gas emissions compared with no measures
Energy consumption is the driver •New Policies Scenario, World Energy Outlook 2012 •** By 2035
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Energy and the Environment – Current Challenges
Manufacturing systems life cycle costs (TCO) 80...95 % Initial startup Training Spare parts
Energy costs
~ $5.950 (96%) Cost price ~ $250 (4%)
Maintenance Labor costs Taxes Insurances
5...20 % Machinery & Equipment
Investment costs 4
Energy Modernization Disposal ...
Operating costs
Three phase motor 1 kW 5 year running time
Example
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Energy and the Environment – Current Challenges
Growth in energy costs will continue
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Technology Change drive
power transmission Hydraulic pump
Constant speed electric motor
with /without valves
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Electro-mechanic
Power density, robustness Controllability Multiple consumers possible Noise Energy efficiency
motor / cylinder
variable speed pumps Force transmission
Variable speed motor drive
motor / cylinder
classic hydraulics Hydraulic pump
Variable speed motor drive
control
Properties
Spindle drive
Power density, robustness Controllability Multiple consumers possible Energy efficiency Noise
Controllability Noise Energy efficiency Multiple consumers not possible (or very difficult) Power density
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Technology Change
Energy saving potential Classic Solution
M Motor losses Pump losses
Total energy
Full motor speed during part load operation. Pump mechanical losses caused by high rotation speed Lower motor and pump efficiency during part load operation High throttling losses caused by proportional valves
Throttling losses
Useful energy
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11.19.2013 | DCUS SET | © Bosch Rexroth AG 2013. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.
Technology Change
Energy saving potential Variable Speed Pump Drives
M Inverter losses Motor losses
Pump losses
Total energy
No throttling losses from proportional valves 40-70% speed reduction during part load operation Increased pump and motor efficiency during part load operation Reduced pump losses by lowering average motor RPM Additional inverter losses
Useful energy
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System Solutions Efficiency
M
AC motor + fixed pump
M
AC motor + variable pump
M
VFD + AC motor + fixed pump
M
VFD + AC motor + variable pump
M
VFD + PM motor* + fixed pump
M
Dynamics
VFD + PM motor* + variable pump
* permanent magnet synchronous motor
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Costs
(esp. for >60kW)
(esp. for >60kW)
System Considerations: Pump Selection
Which pumps are suitable for variable speed operation?
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Speed range Pressure range Direction of rotation Pump efficiency Pump noise Flow and pressure pulsation Pump inertia Quadrants of operation …
???
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Pump selection
Pump speed and pressure limitations Power
p [bar]
lowest speed for continuous operation (i.e. for gear pumps)
Pressure int. Pressure cont.
Noise limit - Motor Fan
Highest efficiency
temporary operation possible (i.e. for gear pumps) n [RPM]
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Cavitation
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- Pump (high frequency)
Noise Reduction
Noise reduction Pump noise depends on: Pump construction Speed and pressure
Pump noise level in dB(A)
… 80
80
70
70
60
60 Axial piston pump Axial piston pump
50
p= 200bar
Internal gear pump
40
40 0
1000
2000
Pump RPM
12
p= 50 bar
50
3000
0
1000
2000
Pump RPM
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3000
Pump selection
Quadrants of operation + Flow Motor operation
Pump operation
pressure
Pump operation
Motor operation
- Flow
Internal gear pump e.g. PGH
Axial piston pumps e.g. A10 VZO
+ Flow Motor operation
Pump operation
pressure
Pump operation
Motor operation
Axial piston pumps e.g. A10 FZG / VZG (for closed circuits)
- Flow
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Pump selection
Mechanical inertia / dynamics Distribution of mechanical inertia of the pump drive 100% = total mechanical inertia of system using internal gear pump Internal gear pump+PM Motor
Axial piston pump+PM Motor
Mechanical inertia
Pump 140%
140%
120%
120%
100%
100%
80%
80%
60%
60%
40%
40%
20%
20%
0% 060
075
100
120
150
190
Maximum Flow (LPM)
14
240
300
Coupling PM Motor
0% 060
075
100
120
150
190
240
Maximum Flow (LPM)
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300
Pump selection
Direct coupling Reduced mechanical inertia Better dynamics (higher acceleration capabilities) Higher efficiency Less mounting space (no bell-housing) Direct coupling Pump
Internal gear pump+PM Motor 120%
PM Motor
Mechanical inertia
100%
Reduced inertia
80% 60% 40% 20%
Sytronix SVP 7000
0% 060
075
100
120
150
190
240
300
Maximum Flow (LPM)
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Pump selection
Fixed or variable displacement? 8
Input Power P (kW)
M
Variable displacement pump, n=1500 RPM
7 6
Variable displacement pump + VFD
5
Fixed displacement pump + VFD
M
4 3
M
2 1 0 0
50
100 150 Pressure p (bar)
200
250
Power consumption for pressure holding Source: Prof. S. Helduser*, ‘Elektrisch-hydraulische Systemtechnik’, O&P 1/2006 *IFD, Technical University Dresden, Germany
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Pump selection
Fixed or variable displacement?
M =
17
p ⋅ Vp 20 ⋅ π ⋅ η mech
M
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Pump selection
Fixed or variable displacement? Pump displacement is reduced A10 VZO pump with two-point control
Reduced load torque during pressure holding
M =
18
p ⋅ Vp (α ) 20 ⋅ π ⋅ η mech
M
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Pump selection
Performance curve VFD + self-ventilated AC motor Fixed displacement internal gear pump- PGH Pump pressure
Axial piston pump with two-point control - A10VZO-EZ4 Pump Pressure
EZ4
Pump speed
Pump speed
- Continuous VFD operation
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Vgmax– max. pump displacement Vgmin – min. pump displacement
Energy Saving
Consider overall efficiency Pump efficiency
Load Torque
Adapt pump displacement to operate in preferred working points
Speed
PMM’s drive efficiency
Pump pressure
Speed
20
M
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Energy Saving by Reducing Motor Speed
Energy saving during stand-by/ idling 4
Input Power P (kW)
3.5 3
M
2.5 2 1.5 1 0.5 Sytronix DFEn 5000
0 0
200
400
600 800 1000 Motor speed n (rpm)
1200
1400
1600
Power consumption of electric motor during standby/ idle Pump size 100cc 40 HP AC motor 600 PSI, 0.25 GPM flow (pilot oil) 21
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Energy Saving by Reducing Motor Speed
Energy saving by reducing motor speed Variable displacement pump+VFD
Efficiency @2200 psi Variable displacement pump, @ 1800 RPM
0.80
10 0.70
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Efficiency
Input Power P (kW)
12
6 4
0.60
Variable displacement pump+VFD
0.50
2 0
Variable displacement pump, @1800 RPM
0.40 0
1000
2000 Pressure p (PSI)
3000
Power consumption of electric motor during pressure holding (Q=0 GPM)
4000
5
15
25 Q (GPM)
35
45
η = Hydraulic Output Power / Electric Input Power
pump A4 125cc 100 HP AC motor Sytronix DFEn 5000
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Engineering: System Sizing in SytronixSize Machine load cycle (p/Q/t)
Select the pump type and size
Investigate drive working points, drive utilization factors, RMS power … 23
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Engineering: System Simulation
System simulation – verify your ideas Model of hydraulic actuators, valves, process forces, lines, etc. Closed loop control algorithm
Speed Variable Pump HPU 24
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Engineering: System Simulation
System simulation – verify your ideas Internal gear pump model, including efficiency (working point dependent) VFD, firmware and p/Q control algorithm Model of PMM Servo Motor with Torque-Speed characteristics
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Engineering: System Simulation
System simulation – verify your ideas Various process variables (speed, position, pressure, power, pump speed etc…)
Evaluation of the simulation: Productivity (cycle time) Dynamic behavior Efficiency
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Sytronix: Bosch Rexroth’s Variable Speed Pump Drives Sytronix Preconfigured Sets Sytronix FcP
Sytronix SVP
•Pressure and flow control
•Pressure and flow control •Force and velocity control •Position control
Basic dynamics
High dynamics
Sytronix DFEn
•Pressure and flow control •Power control High dynamics & high power
Custom Solutions
•Custom system functions •Pressure and flow control •Force and velocity control •Position control
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System Variants- SVP
SvP 7000 – High performance SvP 7000
performance high dynamics
injection molding machine
energy efficient
high accuracy
sample application
control functions pressure control flow rate control force control
system
speed control
U
quadrants
2
n
SG 3~
1 flow
3 28
4
press brake
s
position control pressure
P
Axis control high performance required pressure control flow rate control
3~
M
Axis control high performance required force control speed control position control
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System Variants- SVP
SvP 7000 – High performance pressure 150bar
10 bar
T95%= 150ms
3000 rpm
low RPM during pressure hold
speed
-3000 rpm 0s
29
1.5 s
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System Variants- DFEn
DFEn – Advanced performance DFEn 5000
performance advanced dynamics advanced accuracy
2 independent hydraulic circuits possible
energy efficient
sample application injection molding machine
control functions pressure control
Axis control advanced performance required pressure control flow rate control
flow rate control force control
system
speed control U
position control
paper
P
nCMD
quadrants pressure
2
3~
1 flow
30
3~
M
constant pressure system advanced performance required pressure control
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System Variants- DFEn
Variable speed mode and constant speed mode constant speed mode
variable speed mode
speed speed flow flow swivel angle swivel angle
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Solution examples 1
Slide title n=const
2
n=const
3
n=var.
4
n=var.
5
n=var.
AC motor + 2x fixed pumps
AC motor + variable pump
VFD +AC motor + fixed pump
VFD +AC motor + variable pump (hydr. control)
VFD +AC motor + variable pump (electric control)
6
7
8
9
10
n=var.
VFD +AC motor + variable pump + fixed pump
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n=var.
VFD +PMM motor + fixed pump
n=var.
VFD +PMM motor + fixed pump
n=var.
2x VFD +2x PMM motor + 2x fixed pump
n=var.
VFD +PMM motor + variable pump (hydr. control)
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Solution examples: Compact Axis
Compact Hydraulic Axis The hydraulic circuit completely integrated into the module Max. press force up to 6200 kN (over the entire press stroke) Pressure control ± 0.3 bar Stroke 450 mm, max. 3000 mm Rapid speed forward and return 1000 mm/s Position accuracy ± 1 µm Safety functions up to Performance Level e, SIL3
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Cross Technology System Integration
HPUs and actuators go smart and efficient MLC Process control
Process/ Motion Control Integrated automation bus for real time communication
sercos
IndraDrive MLD Open platform for integration of advanced control and monitoring functions
IAC-R
Smart HPU Compact and modular design wide range of sensors Actuators matching different applications Electro hydraulic linear cylinder
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Smart HPU with Sytronix
Sytronix Compact Axis
Electro Mechanical Actuator
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Application Injection Mould Machine
Increased efficiency ]
New Machine
Machine size : From 110 up to 430 Ton.
Sytronix DFEn 5000
Former solution: - Standard hydraulic solution DFEC - Asynchronous motor fixed rpm - Installed power: 11 kW -75 kW - operation: 24h/240days Customer requirements:
Energy saving
Sytronix solution:
Optimal pressure/ flow control Reduced cooling capacity Reduced noise level Energy efficient system for master – master double pump configuration
Comparison / Saving: Energy consumption per year [Mio. kWh 0.028 0.018
CO2 emission per year [to]
10.9 0.7
10,000 kWh 1,000 EUR 3,900 kg CO2
-34% 35
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Energy System Design Efficient Components Energy on Demand
Application Injection Mould Machine
Increased Efficiency
former solution Rexroth Sytronix solution
Energy consumption per cycle [kWh]
Energy consumption per year [Mio. kWh]
10.9
0.028 4.9
CO2 emission per year [to]
0.018
4,9
0.7
3.2
3,2
Savings per year:
base: ** 10ct/kWh
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10,000 kWh, 1,000 EUR ** 3900 kg CO2 ***
- 34 %
*** 240g / kWh electrical motor power 11kW
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Application Injection Mould Machine
Application – Injection Molding Machine Field tests: Reduced operating power constant vs. variable speed DFE systems 160 ton closing force, 100 cc pump, 30kW motor:
Cycle time 10s: 8%
Cycle time 20s: 32%
Cycle time 40s: 44%
55 ton closing force, 45 cc pump, 11kW motor:
Cycle time 8s: 10%
Cycle time 25s: 20%
Cycle time 60s: 45%
140 ton closing force, 71 cc pump, 15kW motor:
Cycle time 27s: 45%
250 ton closing force, 140cc + 64cc (regenerative) pump, 55kW motor with accumulator:
Cycle time 20s: 8%
270 ton closing force, 140cc + 71cc (regenerative) pump, 55kW motor:
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Cycle time 45s: 30%
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Summary
Advantages Energy saving Depending on the application cycle, variable speed pump drives from Rexroth can reduce energy consumption by 10 to 80 %. Low energy consumption results in reduced energy costs and lowers the user’s “Carbon Footprint”.
Noise Level Reduction Noise is reduced during partial load operation as a result of lower pump RPM. Average noise reductions of up to 20 dBA can be achieved. Installation costs may be reduced if sound insulation designs are not needed
Reduced Cooling In many applications, cooling may not be required on the hydraulic power unit since high operating efficiency reduces hydraulic system heating
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Summary
Advantages Less Mounting Space Eliminating system cooling allows for a more compact design, reduced complexity and lower cost .
Hydraulic and Electric standard components Variable speed pump drives utilize standard hydraulic components.
Forward Looking Technology Variable speed pump drives can help customer requirements for energy conservation.
Easy Integration of flexible control functions Advanced diagnosis and monitoring can help avoid costly machine failures.
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Thank you for your attention! Jan Komsta Manager, New Technologies & Simulation (DCUS/SET1) Tel: +1 610-694-8547 Mobile: +1 610-216-9034
[email protected] Sytronix DFEn 5000
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