High Voltage Regenerative Converter and the Control of Its PWM Rectifier

In this paper is presented the structure and working principle of the cascaded H-bridge multilevel converter with PWM rectifier and phase-shift transformer. Using the leak inductance as the filter reactor of the PWM rectifier can reducing the volume and cost of the converter; the phase-shift secondary side of the transformer can eliminate the current harmonics caused by the single power unit, restraining the grid side harmonic especially the low order harmonic. In the control scheme PLL is employed to track the grid voltage's phase and frequency. The PIR control strategy of the PWM rectifier is to maintain the DC-link voltage stable when feeding the single-phase inverter. In this paper is introduced the mathematic model of the PWM rectifier, its control method and the PIR current control strategy. The waveforms and their spectrums are analyzed through experiments on a prototype testbed. The experiment results verify that the converter can achieve the regenerative ability when operating in the accelerating and decelerating of electrical machines and have a great value in industrial applications.