The Mid-Frequency Power Research Based on Multiple Closed-Loop Feedback

Abstract

In order to solve the grid harmonic current pollution of nonlinear rectifier and the power factor change, the 400 Hz mid-frequency power supply was studied in this chapter. By adopting active power factor correction circuit in the input of inverter power, the harmonic current can be reduced and the input power factor can be improved when the voltage is in sag. The inverter output can cause distortion of the output voltage waveform and bad real-time RMS feedback when it is with nonlinear loads and in dead zone, etc. This chapter proposed a multiple closed-loop feedback control strategy to solve this problem, i.e., the capacitor current was inner loop, voltage was mid-loop, and RMS or the amplitude was outer loop. The chapter used the instantaneous reactive power theory and abc/dq0 transform on the current and voltage detection to improve the real-time RMS feedback. It was verified on the experimental platform controlled by DSP2812 and the results confirmed the viability and effectiveness of the proposed method. The mid-frequency power system with high power factor and multiple closed-loop feedback had both fine static characteristics and improved dynamic performance. It can improve the power factor and reduce the grid harmonic pollution.