| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent the eccentric magnetization of a transformer even if there is a difference between on-times at each half cycle of an inverter, in a charging system for charging a capacitor until its voltage reaches a charging target voltage by using an LC resonance current at each half cycle via the transformer by an output at each half cycle of the inverter. SOLUTION: An on-time operation circuit 11 outputs a pulse having a width which corresponds to the on-time of an inverter switch according to the charging target voltage of the capacitor. A multiplying circuit 13 obtains an amount of positive or negative magnetic flux generated at the transformer according to the on-time by multiplying the on-time by a DC voltage of the inverter. An adder-subtractor 14 obtains a difference by adding and subtracting the amount of the positive or negative magnetic flux. A zero-comparison circuit 15 determines either positive polarity or negative polarity for an amount of the magnetic flux with a zero as a border. A state change permission circuit 16 latches a determination result of the zero comparison circuit. An on-switch selection circuit 17 selects the polarity of an on-output of the half cycle of the inverter according to a determination result of the state change permission circuit. COPYRIGHT: (C)2009,JPO&INPIT
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