To provide an uninterruptible power unit which can suppress the rush current to the input filter capacitor within an uninterruptible power unit at power recovery from power failure.
This uninterruptible power unit, which gets DC power via a PWM converter 6 on whose DC side a DC capacitor is connected from an AC power source 1 and also gets DC power from a storage battery 9 at power failure of AC power and converts it into AC power with a PWM inverter 10 and continues the feeding to a load, includes an input switch 2, a voltage detector 22 which detects the voltage of AC power, an input filter capacitor 4 which removes the harmonics of the PWM converter, a voltage detector 23 which detects the voltage of the input filter capacitor, and a converter voltage control means 35 which controls the AC voltage of the PWM converter so that the voltage of input filter capacitor may accord with that of the AC power source in case that the input switch 2 opens and then it recovers power, at power failure of the AC power source, and shifts into DC voltage control after make of the input switch.
JPH0865917A | 1996-03-08 |
Hideki Takahashi
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