AC-DC converter with parametric reactive power compensation

Resonant converters of 50 (60) Hz ac-dc are described, where each half cycl e of network voltage the capacitor and inductor of an oscillatory circuit a re switched from series into parallel and vice versa, The duration of serie s and parallel connection and also the transformer ratio are parametrically dependent on load. In the case of short circuit, only the parallel oscilla ting circuit operates, This restricts sharply the output current. The react ive power of the capacitor and the inductor compensate with each other, bot h in the cases of series and parallel connection. Therefore, the power fact or is very high from no load to short circuit. This converter fits very wel l for supplying are furnaces, and there is no need for the costly and fast reactive power compensator and filter circuits. The operating principle of the converter, design principles, and a real operating converter rated 8.4 MW supplying a steel-melting are furnace are described.