Study Of Three-Phase Emergency Power Supply System

A novel three-phase Emergency Power Supply (EPS) system, whose main circuit is composed of a bidirectional DC/DC converter and a bidirectional PWM converter, is studied in this thesis. Compared with traditional EPS systems, it has advantages of less power devices and lower cost.Both the Boost converter and the three-phase inverter in the system are controlled by a same DSP board.A double-loop control scheme is used in the Boost converter with an inner loop to control the average inductor current and an outer loop to control the output voltage. A small-signal model for the control scheme is presented and then the compensator parameters are designed.This thesis presents a novel instantaneous voltage feedback control strategy for the three-phase inverter, which improves the control performance through a differential feedback of the output voltage. It overcomes the disadvantage of the poor dynamics of the traditional instantaneous voltage feedback control strategy at light load.With three-phase unbalance loads, voltage unbalance of the DC-link capacitors will occur in the proposed three-phase EPS system. The relationship between the DC component of modulation signal and capacitor voltage difference is analyzed and then an effective control strategy is put forward based on the feedback of modulation signal.The simulation and experimental results prove the validity of proposed control methods.