Analysis and design of a cost-effective voltage feedback control strategy for EPS inverters

This paper presents a cost-effective voltage control strategy with an output voltage differential inner loop for voltage-sources emergency power supply (EPS) inverters. The output voltage differential feedback effectively eliminates the inherent high-resonant peak of the output LC-filter that may cause instability, thus the Q-factor is no longer sensitive to the load and retains 0.5 or less. Since the stability of the system is greatly increased without high-resonant peak, the compensators become easy to design. The instantaneous voltage feedback outer loop with the PI and PID compensator are analyzed and designed in this paper. Simulation and experimental results are given in this paper to verify that the system, with proposed control strategy, possesses very fast dynamic response and leads itself to both linear and nonlinear loads. In addition, the voltage unbalance of DC-link capacitor are taken into consideration and be solved with modulate signals feedback control.