Synchronous Frame Filter Based Harmonic Current Compensation Caused by Dead Time in PMSM Vector Control System

Setting the dead time will make the actual output voltage waveforms of voltage source inverter (VSI) deviate from the expected output voltage waveforms, which will do harm to the speed regulation performance of VSI-PMSM (i.e. permanent magnet synchronous motor) vector control system, so appropriate compensation methods are needed to suppress the influence of dead time. In the paper, AC square wave equivalent method is used to analyze the voltage error and harmonic current caused by dead time in dq coordinate system. Since the output fundamental frequency of PMSM is not fixed during variable frequency speed regulation, it is impossible to use conventional filter to effectively filter harmonic currents in i
d
and i
q
. A dead time harmonic current compensation scheme based on synchronous frame filter (SFF) is then proposed. The effectiveness of the scheme is analyzed and verified by means of simulation.