Investigation of a two-stage boost converter using the neutral point of a motor

This paper discusses about a six-step operation strategy for a proposed two-stage boost converter using the neutral point of a motor. The proposed converter consists of a small boost chopper and a three-phase inverter, which has a boost up function from the use of the leakage inductance of a motor instead of a boost-up reactor, for a DC to AC conversion. When the inverter part outputs a square waveform of 180 degree, the input current has distortion because the neutral point voltage of the motor is fluctuated at three times of the output frequency. The input current distortion because of the voltage fluctuation is reduced to 1/8 smaller by applying a feed forward control. Additionally, in this proposed circuit, the DC current is imposed into the phase current of the motor. Therefore, the influence of the imposed DC current is investigated in a FEM by simulating a 1.5-kW IPM motor.