Load Sharing

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Welcome to the Yaskawa Training Café on Load
Sharing

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Load Sharing with Yaskawa Drives
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What is Load Sharing?
The distribution of a given load over multiple
motors

• What Load Sharing is NOT?

Electronic Line Shaft Software
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Why Load Share?

• Space
• Improve Control
• Eliminate Mechanical Components
• Increase Reliability and Serviceability

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Types of Load Sharing
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Across the Line
Types of Load Sharing

• Advantages
• Inexpensive
• Simple setup

• Disadvantages
• No speed control
• Cannot compensate for mechanical tolerances or
  wear
• High inrush current

• Applications
• Pumps
• Fans
• Limited mechanical

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Single VFD
Types of Load Sharing

• Advantages
• Speed Regulation
• Simple Startup
• Soft Start

• Disadvantages
• VFD failure shuts down the system
• Cannot compensate for mechanical tolerances or
  wear
• V/f control mode only

• Applications
• Pumps
• Fans
• Limited mechanical

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Multiple VFD-Multiple MotorSpeed Master/Torque
Slave
Types of Load Sharing

• Advantages
• Speed Regulation
• Vector control
• Electronic overload

• Disadvantages
• System tuning becomes more complex
• Increase expense
• Must use vector control mode

• Applications
• Conveyors
• Trains

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Obstacles to Load Sharing

• Driving wheel circumference

• Mechanical coupling

• Backlash

• Normal wear tear

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Setup Single VFD with Multiple Motors
Setup of Load Sharing

• Provide each motor with over current protection.
• Add the the FLA of all the motors and size the
  drive for this total.
• For mechanical load sharing all motors should be
  the same size, type, and manufacturer.
• V/f control mode only.

• Parameters
• Set A1-020 V/f mode.
• Set Accel and Decel rates (C1-01 02) others
  rates are available with (C1-03 thru 08).
• Speed reference can be supplied via preset speeds
  or analog inputs.

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Setup of a Multiple Drive System
Setup of Load Sharing

• Motors and Drives must be matched, same model and
  type.
• Using standard drive software one drive is
  selected to be the master.
• Set A1-023, Flux vector mode.
• Speed reference supplied via presets or analog.
• Analog outputs defined as (1) for Speed reference
  (2) another for torque reference.
• Decide on necessary protections required for over
  speed protection.
• Program Accel/Decel Rate(s) (C1-01 through 08)
• Tune ASR via parameters C5-01 (P Gain) and C5-02
  (Integral Time 1)

Master Drive
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Setup of Multiple Drive System
Setup of Load Sharing
Slave Drive

• Set A1-023, Flux vector mode.
• Set D5-011, Torque control
• Analog input A2 programmed for torque reference
  set H3-0913
• Use shielded conductors for speed and torque
  reference signal conductors
• Practice proper wire routing to minimize induced
  noise on analog signals

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Inter-connection and Parameter Setup
Setup of Load Sharing

• Setup of Multiple Drive System

F7 Master
F7 Slave
D5-010 (speed mode (default))
D5-011 (torque mode)
Fwd Run/Stop
H4-011
2-Wire
S1
FM
S1
FM
Spd. Ref. 1
S4
SC
H1-013
S4
SC
Spd. Ref. 2
H4-019
S5
AM
H1-024
S5
AM
SN
SN
SC
SC
Analog Spd. Ref.
Analog Spd. Ref.
A1
A1
For Speed Limit
Analog Common
Analog Common
AC
AC
Torque Ref.
Torque Ref.
A2
H3-0913
H3-0913
A2
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