DSP-based fully digital control of a PWM DC-AC converter for AC voltage regulation

This paper describes the design and implementation of a DSP-based fully digital-controlled single-phase pulsewidth modulated (PWM) DC-AC power converter for AC voltage regulation. The proposed multiloop digital controller consists of a current controller, a voltage controller, and a feedforward controller. This multiloop digital controller was realized using a single-chip digital signal processor (DSP). The PWM gating signals are determined at every sampling instant by the proposed multiloop digital control scheme using a set of detected feedback signals. A software current control scheme has been developed to achieve fast current control of the PWM inverter and decouple the inductor of the output filter. Frequency response behavior of this digital-controlled PWM DC-AC power converter under load variations has been analyzed. The design procedure of the digital controller has been described in detail. Experimental results have been given to verify the proposed digital control scheme. The constructed BSP-based PWM DC-AC power converter system can achieve fast dynamic response and with low total harmonic distortion (THD) for rectifier type of loads