| 摘要 |
PURPOSE:To achieve the elimination of partial magnetization in a main transformer without causing decrease in output, by increasing a trigger angle at a half cycle of saturation side only at the detection of magnetic saturation than a trigger angle of partial magnetization critical point, in a power supply using power control semiconductor elements. CONSTITUTION:In a power supply device for a capacitor load 8 using bidirectional power controlling semiconductor elements 2, voltage and current signals E, E'; I, I' for positive and negative half cycles are detected at voltage, current detectors 9, 10 and polarity discrimination circuits 11, 12. The signals and a trigger signal Salpha are processed at logical circuits 13, 13' and an output via an NOR circuit 22 is given to a transistor (TR)23. At the production of partial magnetization, the TR 23 is nonconductive, a capacitor 28 is charged in a prescribed time constant to compare 24 a voltage signal at a terminal H and a ramp signal U, allowing to increase the trigger signal Salpha at a half cycle of the magnetic saturation of the next cycle than the partial magnetication critical trigger angle. Thus, the partial magnetization of a main tranformer 4 can be avoided without decrease in output. |
