| 摘要 |
PROBLEM TO BE SOLVED: To attain simple and positive zero voltage switch by igniting a main switching element in such a condition that the output current of a current transformer with a primary winding connected is a prescribed value or lower after a bidirectional auxiliary switching element is turned on, and peak resonance current of a resonant capacitor and a resonance reactor is elapsed. SOLUTION: The detection signal of a current transformer CT is detected by two resistors R1, R2, and zero current is detected by comparators COMP1, 2. A main switching element is on-gated by conducting synchronization for control signals SG1, 2 controlled by a CPU with the signal of the comparator and D flip-flop DFF1, 2, that is, by conducting synchronization with respective last transition signals of the COMP1, 2 and DFF1, 2 respectively, a GS1 or an SG2 is outputted, which corresponds to any one on-gate signal of the main switching elements. An auxiliary switch is turned on when the input signal SG1 is at an H-level, and another auxiliary switch is turned on when the SG2 signal is at the H-level. It is thus possible to prevent an unnecessary gate signal from entering the main switching element. |
