Estimated-speed-aided stabilizers for sensorless control of interior permanent magnet synchronous machines

Robust rotor position observer is one of the key issues in the position sensorless interior permanent magnet synchronous machine (IPMSM) drive system design. Several model-based observers have been proposed to estimate rotor position and speed without mechanical sensors. However, because of unmodeled nonlinearities, e.g., inverter dead-time effect, inductance cross saturation, as well as other machine parameter drift and variation, there will be instability phenomena in a close-loop sensorless control with estimated position and speed during large load transients. This paper proposes two estimated-speed-aided stabilizers (ESASs) to improve the transient stability and large transient ride through capability of a sliding-mode observer (SMO)-based position senseless IPMSM drive. Since the change of rotor speed is much slower than that of rotor position in medium and high speed range, the proposed stabilizers utilize the estimated rotor speed to predict a rotor position, which is then used to assist the sensorless control system remain stable during large load transients. Both stabilizers are validated by simulations in MATLAB Simulink and experimental results on a practical high power IPMSM drive system.