Experimental Verification of Current Source Inverter with ZVS Commutation Circuit

This paper presents a current source inverter suitable for high voltage and high power motor drives. This inverter uses thyristors as main switching devices and utilizes ZVS commutation circuit. Compared with conventional load commutated inverter, the proposed inverter has advantages of good power factor and capability of self-starting. In this paper, a test model of the proposed inverter was evaluated. We verified that the test inverter model operates with power factor 1. And it is possible to start the inverter even if motor speed is 0. Moreover, synchronous motor with 2 windings was driven by 2 proposed inverter. As a result, it was confirmed to be able to decrease torque ripple of the motor and harmonic component of voltage source. In addition, the operation of ZVS commutation circuit was evaluated by simulation and experiment. As a result, it was verified turn-off loss mainly depends on inductance of ZVS commutation circuit, and doesn´t depend on gate resistance. Moreover, when switching device turns off the current, the voltage of the switching device is almost 0V. That is, even if the inductance is large, the peak voltage of the switching device is low, and the loss is small. Therefore, ZVS commutation circuit can be easily composed because the circuit need not be made low inductance. From these results, a large capacity drive system can be easily offered by using the proposed circuit.