This Electric Power Steering (EPS) System design includes a MotorSolve generated 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 Ideal PMSM and Drive", an ideal PMSM model which does not include cogging torque, saturation and torque ripple behavior that is included in the MotorSolve generated model herein, So this design shows the significant (and realistic) effect of that behavior in this power steering application.
In another companion design, "EPS System with MotorSolve Generated PMSM Model and DQ/SVM Drive", both the MotorSolve motor model and a sampled-data D-Q control algorithm with space-vector modulation are included. This shows the ability to develop motor controls and drives at the abstract level as well as at the circuit level.