Stability issues of high-speed PMSM feedback control systems

This paper describes stability issues on both open loop and feedback loop with a high speed permanent magnet synchronous motor (PMSM). The motor discussed in this application is a 3kW, 42 000 rpm, 560 V PMSM. The problems of time delays-computational delay-in the control loop are discussed. It is shown that for this specific case, the time delay in the feedback loop has to be lower than 1/20 of the electrical time constant of the machine itself. A solution for higher machine stability with a Field Programmable Gate Array (FPGA) controller system is proposed.