DC-Link Current Minimization Scheme for IM Drive System Fed by Bidirectional DC Chopper-Based CSI

Compared to a voltage source inverter (VSI), a current source inverter (CSI) retains the advantages of inherent boost capacity, friendly output voltage waveforms, and high reliability in motor drive systems. As the motor drive usually operates on variable speed and torque occasions, the CSI needs a prestage circuit and control scheme to generate a proper dc-link current. Because the dc-link current minimization can reduce the losses of semiconductor devices and the total harmonic distortion (THD) of stator current, a dc-link current minimization scheme for CSI-fed induction motor (IM) drive system fed by bidirectional dc chopper-based CSI is proposed in this article. First, the calculation method for the reference of the minimum dc-link current and the optimal exciting component of stator current is derived. Second, the hysteresis control scheme based on the bidirectional dc chopper is designed to regulate the dc-link current tracking to the reference under different operation modes. Third, the influence of the parameters mismatch in the steady state is discussed. Finally, the correctness and feasibility of the dc-link current minimization scheme proposed in this article are verified by simulation and experimental results.