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Tuning Load drive on performance dynamometer

Article ID: 517 | Rating: 4.3/5 from 3 votes | Last Updated: Sat, May 29, 2010 at 11:34 AM

Configuring Emerson motor drive for best torque per amp

For the load side of the D&V dynamometer test stands, the Emerson motor drives use an internal operating point selection to choose the operating point at which the motor is run. The motor drive must be tuned in order achieve the highest torque per amp value. This document summarizes the tuning for the Emerson/Control Techniques Unidrive SP motor drives.

This tuning is not necessary on the DUT motor drive since operating points are selected manually.

Drive Tuning

Parameter	Description	Comments
3.10	Speed Controller Proportional Gain	Speed loop gains control the speed stability of the load motor.In general, increase the value of the Kp to increase stability.If Kp is too small the system will not make large enough adjustments in response to error.If Kp is too large the system will become unstable and oscillate with large changes in response to speed error.
3.11	Speed Controller Integral Gain	In general, decrease the value of Ki to increase stability, at the expense of step response.If Ki is too low, the system will take too long to reach equilibrium.If Ki is too high the system will make changes quickly, resulting in a ringing behavior of overshoots and undershoots as the system stabilizes.
4.12	Current Demand Filter	Update rate of the PID loop
4.13	Current Controller Proportional Gain	If Kp is too small the system will not make large enough adjustments in response to error.If Kp is too large the system will become unstable and oscillate with large changes in response to error.
4.14	Current Controller Integral Gain	If Ki is too low, the system will take too long to reach equilibrium.If Ki is too high the system will make changes quickly, resulting in a ringing behavior of overshoots and undershoots as the system stabilizes.
5.25	Stator Inductance	Set this value if you know it.
5.08	Rated Load RPM	Increasing or decreasing this value moves the operating point below base speed.Modify this value in small steps and watch motor torque per amp (torque measured by torque cell / total current).Move this value in the direction that increases torque per amp until you reach a plateau and start to decline.
5.09	Rated Voltage	Increasing rated voltage can allow a bit more headroom for the PID loops to operate
5.10	Rated Power Factor	The power factor controls the current used to induce the rotor field.Decreasing the power factor puts more energy into the rotor field.Make small changes in the power factor (1 percentage point) in the direction of increasing torque per amp.Find the optimal division of torque producing current and rotor excitation current by finding the power factor that produces the maximum torque per amp.