| 摘要 |
PURPOSE:To improve the stability of the output voltage of an AC/DC converter by comparing a second reference value higher than a first reference value with the output voltage, and providing a photocoupler for stopping the conduction of a switching element when the result of comparison exceeds the reference value. CONSTITUTION:A converter such as an inverter or the like is composed of bridge type rectifiers 2, a filter 3, a DC reactor 4, a switching element 5, a diode 6, etc., a control circuit has a constant-voltage control circuit 8 and a current tracing circuit 9 to control an output voltage constantly and to control an output current in a pulsating waveform. In this case, a DC power source 12 for supplying a DC power voltage to both circuits 8-9 is provided, and comparators 30, 31 for comparing an output voltage VL with second, third reference values V2, V3, and first, second photocouplers 32, 33 connected to the outputs of the comparators 30, 31 are provided. Thus, an output current becomes a waveform vibrated in a predetermined range determined by the output level difference of amplifiers 17-18 at a reference waveform as a center.
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