| 摘要 |
A power conversion apparatus has a PWM power converter coupled to an A.C. power supply on one side and to a D.C. load on the other side, a voltage controller for adjusting the D.C. output voltage from the converter, a power factor controller for adjusting the power factor on the A.C. side of the converter, a command generator for generating a PWM modulation factor and a phase signal in response to the voltage and an output from the power factor controller, and a PWM modulation unit for controlling the converter in response to these command signals. The power factor controller is controlled to reduce its power factor when a control parameter relating to the modulation factor of the converter approaches its limit value, and the power of the D.C. load is limited when a control parameter relating to the input power of the converter approaches its limit value, such that the power factor of the power converter is allowed to be reduced and the power of the D.C. load is limited respectively in each designated region, thereby preventing any overcurrent even if the power supply voltage fluctuates. As a result, continuous operation is maintained, making it possible to reduce the capacity of the converter required for generating the same output power over the conventional converter.
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