| 摘要 |
PURPOSE:To make instantaneous change-over possible from a commercial power supply to an inverter and to obtain a commercial power supply type uninterruptible power supply device with an improved power efficiency constantly by using high-speed switching elements for an AC switch where an AC power supply is connected and an inverter where a DC power supply is connected. CONSTITUTION:Transistors Q1 and Q2 consisting of IGBT are used as switching elements at an AC switching part. Also, transistors Q5-Q8 consisting of IGBT are used as the switching elements of an inverter. Therefore, when the abnormality in the input commercial power supply is detected, current mode control is instantly switched to voltage mode control for feeding power to the inverter. Namely, at the same time when the transistors Q1 and Q2 are turned off, an output voltage V0 is compared with a reference sinusoidal waveform by a comparison circuit so that the output voltage waveform becomes a sinusoidal waveform and then the transistors Q5-Q8 are subjected to PWM control by an inverter AVR siignal which is the difference, thus reducing instantaneous waveform control and power consumption. |
