| 摘要 |
PROBLEM TO BE SOLVED: To stably extract the electrical power required for a load with higher accuracy from the power source which shows a large voltage variation. SOLUTION: When a secondary voltage is reduced lower than the primary side using a voltage control circuit including a switching element 11 for dropping the voltage and a switching element 19 for raising the voltage, the element 19 for raising the voltage is always opened and the element 11 for dropping the voltage is opened and closed with a gate pulse which changes the pulse width Wd inversely proportional to a voltage error, the pulse period is increased and pulse width is also increased almost inversely proportional to a difference between a primary side current and a secondary side current when the pulse width exceeds the upper limit value Wdmax to which the element 11 can respond. When the secondary side voltage is increased higher than the primary side voltage, the element 11 for dropping the voltage is always closed, the element 19 for raising the voltage is opened and closed with a gate pulse which changes the pulse width Wu inversely proportional to the difference explained above, and the pulse period is increased almost inversely proportional to the difference explained above when the pulse width becomes lower than the lower limit value Wumin to which the element 19 can respond.
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