| 摘要 |
A DC/AC converter comprising a semiconductor switch circuit provided in the primary winding of a transformer having the secondary winding connected with a load and performing PWM constant current control on each switch in the semiconductor switch circuit. An intermittent control operation is employed in combination with the constant current control in order to widen a range of the AC power that can be supplied to a load in the lower limit direction thus performing fine control. In the intermittent operation control, the error signal of PWM control is brought to zero during the off interval of intermittent operation. During the on and off intervals of intermittent operation, the error signal of PWM control is decreased or increased gradually by charging or discharging the capacitor in a feedback circuit thus ensuring slow start and slow end of PWM current control during both the on and off intervals of intermittent operation.
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