| 摘要 |
PROBLEM TO BE SOLVED: To increase an input power factor, by determining a phase control amount of nearly sine-wave pulse width modulated voltage so that the supply current may be made into a sine wave by means of an output voltage phase controller. SOLUTION: An output phase controller 11 makes a proportional and integral control of a difference between a target value (Vdcm) of the DC bus voltage and the output (Vin) of a supply voltage detecting means 7, and then determines a phase control amount (θconv) of the pulse width modulated voltage. The magnitude of nearly sine wave pulse width modulated voltage to be generated at an AC reactor 5 side of a switching element 6 is made the same as Vin. Nextly, nearly sine wave pulse width modulated voltage is determined fromθconv and Vin and the determined voltage is outputted to a pulse width modulation controller 10, which generates nearly sine wave pulse width modulated voltage at the AC reactor 5 side of the switching element. By controlling the DC bus voltage constant with only a phase of the nearly sine wave pulse width modulated voltage as a control amount, a controlling and calculating circuit can be built up easily.
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