Digitally-Controlled Single-Phase Single-Stage AC/DC PWM Converter

The paper presents the implementation of a fully digital controller for a boost integrated ac/dc PWM converter. The considered converter has the following basic features: high power factor, full control of the dc output voltage, high-frequency line filter inductor and insulation transformer. Its main advantage is the complete integration of a rectifier and an inverter stage, requiring only four IGBTs and six diodes. The converter is described in detail and the structural limitations of its operation are highlighted. The paper focuses on the converter control strategy describing in detail the implementation, by means of the TMS320F240 digital signal processor, of a fully digital, predictive, input current control technique. An application specific modulation strategy is also developed that allows simultaneous input current and output voltage control. The control system is finally tested on a 0.5 kW laboratory converter prototype. The presented results validate the design procedure and illustrate the achievable converter performance.