SOURCE-SIDED POWER FLOW-CONTROL OF A SINGLE-PHASE AC-TO-DC SERIES-RESONANT POWER-SUPPLY

The objective of an AC-to-DC converter is to control the output waveform. The energy emanated from the source is adapted by passive filters, which is often a compromise between volume and effective use. A classical rectifierfilter network presents a major disadvantage: a power factor less than one which is caused by distortion of the source current. The resolution of the high-frequency input current of the series-resonant converter introduces the possibility of controlling the waveform of the source current accurately. In combination with the accurate positioning of the high-frequency current pulses, it is possible to influence the exchange of power with the source by the introduced method of active filtering. A power factor equal to one would lead to an optimal operation. The method introduced can select any value for the power factor, even for distorted voltage waveforms. However the zero-crossing of the AC source voltage introduces the necessity of storing energy. Bulky low-frequency storage elements increase the specific volume and weight of the converter while the exchange of energy with storage elements decreases the overall efficiency. The energy stored in the resonant circuit is fundamentally too low to solve this problem. The stored energy in the output capacitor, necessary to decrease the high-frequency ripple voltage, is available for these purposes. To meet the optimal conditions for the power factor at the source, a bipolar flow of energy is required. The theory of single-phase AC-to-DC series-resonant power conversion with controllable reactive power is explained. The results of simulation and experiment will establish the extensive possibilities of the proposed systems. © 1990 Springer-Verlag.