Direct power control of PWM converter without power-source voltage sensors

This paper proposes a novel control strategy of a pulewidth modulation (PWM) converter with no power-source voltage sensors. The strategy has two main features to improve a total power factor and efficiency, taking harmonic components into account without detecting the voltage waveforms, One feature is a direct instantaneous power control technique for the converter, which has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter. The other feature is an estimation technique of the power-source voltages, which can be performed by calculating the active and reactive power for each switching state of the converter from the line currents. A digital-signal-processor-based experimental system was developed, and experimental tests were conducted to examine the controllability. As a result, it was confirmed that the total power factor and efficiency were more than 97% and 93% over the load power range from 200 to 1400 W, respectively. These results have proven the excellent performance of the proposed system.