| 摘要 |
PROBLEM TO BE SOLVED: To retain a stable gate voltage by superposing a secondary coil winding voltage and a tertiary coil winding voltage and applying them to a MOSFET for commutation as a gate signal voltage by switching or applying only the secondary coil winding voltage or the tertiary coil winding voltage in negative biasing. SOLUTION: Since the positive voltage of a pulse transformer T2 is outputted with a coil winding ratio of N1:(N2+N3) even if duty becomes small during PWM control, a gate voltage is given satisfactorily. Since a negative voltage does not exceed the rating of the gate voltage due to the number of turns of N1:N2, it is increased by the positive voltage. As a result, by switching the secondary side coil winding voltage of the pulse transformer for utilizing as a single or superposition gate signal, a stable gate voltage can be retained by adjusting the number of turns and the ratio of the number of turns of each coil winding even if the duty ratio of an input pulse width signal changes, thus reducing loss.
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