| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply wherein large reverse power is prevented from being applied to a switching device. SOLUTION: When a transistor Q1 is turned on, current is allowed to flow in a main inductance Tr1am of a primary windng Tr1a and the transistor Q1 from a smoothing DC power circuit 4 and then voltage is induced in a secondary winding Tr1b and then power is supplied to a lighting circuit 8. In the main inductance Tr1am, magnetic energy is accumulated. When the transistor Q1 is turned off, the magnetic energy accumulated in the main inductance Tr1am is transferred to a sub inductance Tr1as of a reverse phase and a resonance capacitor 4 and makes a free oscillation. As the main inductance Tr1am and the sub inductance Tr1as are 180 deg. out of, the voltage at the connection between the main inductance Tr1am and the sub inductance Tr1as, that is, the voltage divided by the main and the sub inductance Tr1am and Tr1as, is applied as reverse voltages to the filtred DC power circuit and the transistor Q1. The voltage to be applied to the transistor Q1 can be reduced by the sub inductance Tr1am. |
