Sensorless V/f control of high-speed surface permanent magnet synchronous motor drives with two novel stabilising loops for fast dynamics and robustness

This study introduces a novel fast dynamic sensorless control for high-speed surface permanent magnet synchronous motor (SPMSM) drives based on a V/f control with two stabilising loops to correct the stator voltage amplitude and phase by a closed loop for zero interior reactive power (implicitly pure i_q control). This solution avoids Park transformations, speed and current closed-loop control - typical for vector control, and also rotor position and speed observers. It is robust to stator resistance and PM flux variations. Comprehensive experimental test results are given with a 50 Vdc MOSFET inverter and a SPMSM with very low electrical time constant of 0.5 ms and low inertia. Fast speed reversal of +10 000 rpm within 160 ms with good load rejection, starting from any initial rotor position and running to 20 000 rpm constitute the paper core. The speed (torque) dynamics are similar to those of vector control method with encoder, but online computation effort is notably lower, with superior control robustness. This solution should be particularly suitable for very high-speed drives with rated frequency of 0.5-10 kHz, where online computation time cycle is inherently small.