| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve high efficiency motor driving inexpensively through a simple arrangement where the target DC voltage can be altered for voltage variation of an AC power supply by setting the target DC voltage at a lower limit within the operational range of a power factor improving circuit and minimizing loss of the power factor improving circuit. <P>SOLUTION: Determination of the target DC voltage is proportional to the frequency of a compressor 12 and it is further made proportional to the voltage value of an AC power supply. The target DC voltage is determined to satisfy the conditions that a power factor improving circuit 4 operates even if the power supply voltage varies and that the compressor 12 can be driven without causing voltage saturation, and the target DC voltage is set at a lower limit within the operational range of the power factor improving means for each voltage value of the AC power supply. <P>COPYRIGHT: (C)2008,JPO&INPIT |
