| 摘要 |
A stabilized power supply unit designed to supply the power from the commercial power source as far as the commercial power source is normal but supply the power from a battery that can be made available by an automatic switching device when the commercial power source has failed, wherein the AC voltage from the commercial power source is rectified by a rectification circuit to obtain almost equal DC currents on both the positive and negative sides of the common line while the commercial power source is normal. Said DC voltage is chopped by the boosting chopper circuit to boost the voltage on both the positive and negative sides. The boosted voltage is converted into the AC voltage through the DC-AC inverter, and the high-frequency component of the AC voltage is compressed through the filter in order to be outputted as an AC voltage of specified frequency. When the AC voltage is not inputted due to the failure of the commercial power source, the DC voltage from the battery is applied to the DC-AC inverter in order to be converted into the AC current and outputted as the specified AC voltage through the filter. In this manner, the direct transmission circuit with a common line can be formed without including an isolation device.
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