Impact of parameter estimation errors on feedforward current control of permanent magnet synchronous motors

Abstract

Feedforward current control is a widely employed control technique for cost-sensitive permanent magnet synchronous motor (PMSM) drive systems since it does not require current measurements. Feedforward compensation is usually static, but dynamic compensation can be also employed to improve the bandwidth of the current control loop. Typically, the feedforward current (or torque) control requires accurate knowledge of motor parameters to achieve robust steady-state and dynamic performance. However, in practice, the machine parameters vary highly nonlinearly as the operating condition of the PMSM changes. Therefore, it is important to analyze and understand the impact of machine parameter estimation errors on the steady-state as well as dynamic performance of the system. In this paper, the analytical expressions for the actual currents in a feedforward current controlled PMSM drive system under the presence of parameter estimation errors are developed. The presented analysis is verified by experimental results on a commercial PMSM.