| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable detection of the voltage phase of a three-phase AC power supply when the phase shifted from on/off operation timing of a regenerative transistor, and to correct on/off operation timing of the regenerative transistor when unbalance and harmonic frequency distortion exist in the voltage of the three-phase AC power supply. <P>SOLUTION: A phase detection part 20 detects voltage phase of the three-phase AC power supply 2 by using zero crossing detection of a phase voltage. A regenerative signal generation 22 carries out on/off operation of the regenerative transistors Tr1-Tr6 based on a phase voltage phase detection signal from the phase detection part 20. The regenerative signal generation 22 monitors voltage waveform of the three-phase AC power supply 2 based on output of an AC voltage waveform detection part 21, corrects change timing of generated on/off driving signals of the regenerative transistors Tr1-Tr6 when deviation is detected to substitution timing of phase voltage, detects phase in which voltage is maximized when terminal voltage of a smoothing capacitor C is decreased, and corrects regenerative current sampling phase for stopping regenerative operation. <P>COPYRIGHT: (C)2004,JPO |
