| 摘要 |
PROBLEM TO BE SOLVED: To suppress a cross current by forming a voltage command of a voltage control system according to a commercial power source voltage in the case of switching a commercial power source into an inverter output voltage, thereby controlling an amplitude of the output voltage to mach the commercial AC power source. SOLUTION: An input voltage(commercial AC power source 2) of an uninterruptible power source 1 is detected by a voltage detector 6, and its phase is detected by a phase detector 9. A reference sine wave voltage generator 10 contains a reference voltage setter, has a predetermined peak, forms voltage commands Vuv0, Vwv0 synchronized with the power source 2, and inputs it to a voltage command forming unit 4. A voltage control system 31 inputs command values Vuvr, Vwvr of an inverter line output voltage to be outputted from the unit 4, and voltage controls so that both coincide with the output voltage of an LC filter 14 as a feedback amount. The calculated voltage command is pulse-modulated by a PWM control system 32, and a gate signal for ON/OFF controlling a switching element of a voltage PWM inverter 13 is formed. |
