Analysis and design of the DSP-based fully digital-controlled UPS

This paper proposes a new control scheme based on two parallel controllers to improve both the steady and transient state responses of close-loop regulated pulse-width-modulated (PWM) inverter for UPS. The controller consists of the repetitive and instantaneous controllers. The repetitive controller is designed to eliminate periodic disturbance and the instantaneous controller is synthesized for transient state response improvement. Design procedure is given for synthesizing the repetitive and instantaneous controllers. The proposed control scheme has been realized using a single-chip digital signal processor (DSP) TMS320F240 from Texas instruments. A 7.5 kVA UPS has been constructed to verify the proposed control scheme. Simulation and experimental results show that the DSP-based fully digital-controlled UPS can achieve both low total harmonics distortion and good dynamic response.