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Wake and Shake Function WSCNFG 1

Valid for S300/S700 from firmware version 2.53.

General

Instead of Wake & Shake function 0 , this alignment method uses a position control loop with the angle of the commutation vector as control output. The position control loop takes the initial start position of the motor as constant position command and controls the motor motion and position by turning the commutation vector. The amplitude of the motor current is set to REFIP2. When the alignment time MPTIME expires the output of the position controller represents the ‘zero torque position’ vector of the original method.

  Advantages

  • motor movement < 5° el (depending on control loop tuning)
  • no oscillation, even with air bearings (depending on tuning)

Disadvantages

  • control loop has to be tuned according to motor (and load) inertia
  • the motor must be free of torque load during commutation alignment. Torque load and
  • friction results in alignment error.

Attention !
Due to the torque load restrictions, there is no support for vertical axis applications.

Control loop tuning

Tuning the PID Controller is best done in the following steps:

  1. Set all Parameters MPKP, MPKI, MPKD to 0 and set time MPTIME to approx. 2000 mseconds.
  2. Set REFIP2 to the desired motor current value.
  3. Then start alignment test with “CALCMP 1000”. This command starts the commutation alignment for 1000 cycles. The motor will be moving back and forth and will oscillate between two positions:
  4. Increase the MPKD-Parameter (example: 5000) until the oscillating disappears
  5. Increase the MPKP-Parameter (example: 600) to minimize position error
  6. Increase the MPKI-parameter (example: 1000) to let the motor return to its start position.The integral part gives a static position error of 0, so the motor does not run away if the customer restarts the alignment several times.

  7. Set the alignment time MPTIME (example: 1200ms) to the lowest value according to the response of the system

  8. To use the new method instead of the standard Wake & Shake function, set the parameter WSCNFG=1. Save all the parameters with the SAVE command and switch the drive off and on. At the first power stage enable a “CALCMP 1” command is executed instead of the Wake & Shake procedure.
WSCNFG 0 activates the standard Wake & Shake procedure.