Sliding Mode Control for Permanent Magnet Synchronous Motors using Conditional Integrators

We present a conditional integrator based sliding mode control (SMC) design for position/speed tracking in permanent magnet synchronous motors (PMSMs) with possibly unknown parameters and load torque. A continuous SMC is designed to include integral action only inside the boundary layer to recover asymptotic regulation in the case of asymptotically constant exogenous references/disturbances, retaining the transient performance of ideal (discontinuous) SMC, without the problem of control chattering. In the case of speed regulation, the control design can be viewed as a specially tuned PI controller with anti-windup, while it becomes a PID controller with anti-windup for position regulation. The design easily extends to the case of sinusoidal references/disturbances by incorporating a conditional servocompensator. Analytical results for regulation and performance recovery of ideal SMC are provided, and the efficacy of the design is validated by numerical simulations.