Abstract: This paper presents a multi drive variable frequency speed control system. The topology of the system is AC-DC-AC structure, and the control performance is AC-AC direct conversion. Zero current commutation strategy and PWM control strategy can get good input current and output voltage waveform, and realize safe commutation. In the following, the correctness of the theory proposed in this paper is proved by the simulation results.

Key words: multi-drive system, zero-current commutation, rectify control, inverter control