Finite control set MPC with high frequency injections for sensorless position and speed estimation of a PMSM

A new control algorithm for operation of surface mounted permanent magnet synchronous machines in very low speed and standstill using finite control set model predictive control (FCS-MPC) and high frequency signal injection for estimation of the rotor position is proposed. Estimation of the rotor position is based on the standard injections of high frequency signal into the voltage command for a PWM. It is intended to achieve the same effect using the FCS-MPC. The FCS-MPC usually operates with a short sampling period, therefore the estimation algorithm needs to be computationally cheap. Moreover, the cost function needs to be modified to secure injection of high frequency (hf) voltage signals into a given axis in a reference frame linked with the rotor position. In this paper, a method of injection of a harmonic signal using FCS-MPC is proposed, using an extension of the cost function. Rotor position and speed estimation is based on the conventional phase-locked loop. Theoretical assumptions are verified by both simulations and experiments on a laboratory prototype of PMSM drive with rated power of 250 W.