Research On PIP Dual Loop Digital Control Technique For PWM Inverters

With the demands of important departments and electric equipments for higher quality power supply ascending,high performance PWM inverter are taken more and more attention. With its incomparable merits, digital control is gradually taking place of analog control. Corresponding to digital, come along with many kinds of discrete control method. It impulse the development of the inverter control technology effectively. Through logical designing controller, it can make sure the output voltage waveform of the system has good steady and dynamic characteristic.This paper focus on output voltage and inductor current feedback dual loop control digital technology of inverters, introduces the analog and digital math model of the single-phase full-bridge PWM inverter, and discusses differences of the both. In allusion to the no-load characteristic of the inverter, this paper brings forward the dual loop control technology, which can improve the speediness and state-steady. Based on the dual loop control technology can divide to inductor current feedback and capacitor current feedback, both of them are analyzed and compared in the paper. And finally the dual loop control with inductor current feedback and load current forward feed compensation is chosen. Then based on the pole-assignment theory to design the controller, the dual loop PI-P control is adopted.It is the necessary of using state-observer in the digital control, so considering the infection of one pulse delay to the system; this paper designs the state-observer and the disturbance observer separately. In the same time, for advancing the steady characteristic of the system more, especially the quality of the output voltage waveform with nonlinear load, it proposes import the repetitive compensator in the state-observer. It is proved that the repetitive compensator can really advance the steady characteristic of the system by simulation.Based on the theoretic analysis and calculation for the control parameters, a single phase inverter applying dual loop digital control technique with output voltage and inductor current feedback is researched in the paper. The experiment results which accord with theoretic analysis are presented.