MTPA based operation point speed tracking for PMSM drives without explicit current regulation

A maximum torque per ampere (MTPA) based speed control approach without explicit current regulation is laid out in this paper for permanent magnet synchronous machines (PMSMs). The presented control strategy is able to achieve speed tracking by considering the variation of the voltage amplitude and angle with respect to the machine's speed and torque. As a result, the current control loop is avoided, simplifying the overall control scheme as opposed to several control methodologies available in literature. The proposed theoretical developments can be applied to both surface-mount and interior PMSMs. Moreover, in order to achieve a robustness to uncertainties, a feedback controller is introduced to correct for residual errors. The effectiveness of the proposed method is verified by conducting experiments a 10 HP interior PMSM. Experimental results along with comparison against the well-known MTPA field oriented vector control technique highlight the performance of the proposed controller in transient, steady-state, and standstill conditions. A quantitative energy efficiency index is provided to better illustrate the MTPA trajectory tracking performance. As it is revealed, the proposed control scheme achieves a fast recovery from unexpected load changes which makes it a good candidate for high-performance PMSM drives.