Control of A Three-Phase Diode Rectifier with An Instantaneous Reactive Power Compensator

This paper proposes control techniques for a three-phase diode rectifier with an instantaneous reactive power compensator (IRPC) whose the dc-link voltage is connected to a buck converter to control power of a dc load. At the dc-link voltage, a small film capacitor is inserted in the system causing a square waveform for the ac currents of the rectifier. Moreover, the three small ac inductors are used to reduce the current ripple from the switching frequency of the buck converter. These ac inductors cause the commutation overlap in the diode rectifier, and the control system would be unstable because of the resonant frequency between the ac inductors and the dc-link capacitor. Hence, this paper presents the analysis and the control technique performance of the system based on estimated power of the rectifier without detecting ac current of the rectifier. A 4.5-kW experimental setup was used to verify the control methods. As a result, the proposed techniques can control the grid current as a sinusoidal waveform with a THD
_i
and an efficiency of 4.68% and 97.8%, respectively.