As the key part of the UPS(Uninterruptible Power Supply) system, inverters are required to get high quality output voltage waveform. To achieve nearly sinusoidal output voltage even with nonlinear loads, many waveform correction techniques have been proposed. Since the instantaneous feedback control technique is a real-time control method according to the current error of output waveform, once the controller is designed properly, it could achieve nice static characteristics with good dynamic response. The dissertation focuses on the research for dual loop control technique with instantaneous voltage and current feedback for PWM inverters. Both dynamic and static characteristics are analysed by simulations and experiments.Based on the state-space averaging and linearization technique, the mathematical model is given in form of transfer function and state equations. The influence of dead-time, over-modulation and nonlinear loads on output voltage in single-phase full-bridge inverters is analyzed in detail. The method which reduces equivalent output impedance of the close loop system to eliminate the disturbance of nonlinear load is reasonable.The voltage and current dual loop control system is divided into inductor current feedback and capacitor current feedback. Both of them are analysed and compared in the paper, the dual loop control with inductor current feedback and load current forward feed compensation included. The dual loop control with capacitor current feedback is applied in the following simulation and experiment by analog method. Depending on the difference of controller for the current loop, the dual loop control is classified into two methods: current loop using P controller with voltage loop using PI controller(Dual loop PI-P control)and both current loop and voltage loop using PI controlle(rDual loop PI-PI control). Controller parameters are obtained with pole assignment technique in the condition that both dual loop PI-P control system and dual loop PI-PI control system have the same desired damping ratio and nature frequency. The simulink results show that dual loop PI-PI control technique for inverters could get nice static characteristic and well dynamic response. It could get high quality output waveforms even with nonlinear load. Dual loop PI-P control inverters have nice static characteristic with linear load, but it is not superior to the dual loop PI-PI control technique in characteristic with nonlinear load. Analysis and simulink comparison present that the characteristic with linear load could get better when the system has higher desired nature frequency.Based on the theoretic analysis and calculation for the control parameters, a single phase inverter applying dual loop analog control technique with output voltage and capacitor current feedback is researched in the paper. The experiment results which accord with theoretic analysis are presented.

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