EPS System with Ideal PMSM and Drive

This design includes an ideal Permanent Magnet Synchronous Machine (PMSM) model, as well as a continuous D-Q controller and drive circuit. The mechanical load model includes static and kinetic friction, a steering force that varies with rack displacement, as well as various mass, inertia, damping and spring/stiffness elements of the steering system. The steering torque, applied by the vehicle's driver, is assisted by torque from the motor scaled by the gear ratio. For the control, a non-linear gain profile is specified in the "torque_assist_table" function, and a lead-lag compensator is used to improve system stability.

Note that this is a "tunable" design. Many of these system parameters can be changed by the user. Then a new simulation can be run and the updated results can be observed in the waveform viewers.

In a companion versions of this design, "EPS System with MotorSolve Generated PMSM Model and Ideal Drive", the ideal PMSM is replaced with a more realistic motor model generated by MotorSolve, the motor design tool. That model includes cogging torque, saturation and torque ripple behavior, which is seen to have a significant effect in this power steering application.

A second companion design, "EPS System with MotorSolve Generated PMSM Model and DQ/SVM Drive", uses both the MotorSolve motor model and also a sampled-data D-Q control algorithm and space-vector modulation (SVM) to control the switches in a power electronics circuit. This shows the ability to develop motor control and drives at the abstract level and also at the circuit level.

Mike Donnelly's picture



Mike Donnelly

Joined November 8, 2013
Design added Friday, April 20, 2018 | 2:52 pm PDT