| 摘要 |
PURPOSE:To improve system efficiency by splitting voltage by a capacitor and grounding the midpoint potential of the DC voltage circuit through a resistor, and by detecting the grounding of the system by the current change by the grounding resistor. CONSTITUTION:DC voltage is obtained by rectifying a 3-phase AC power source 7 by a converter 1. The DC voltage is smoothened by a smoothing capacitor 2, and the DC voltage is stabilized simultaneously. The DC voltage is PWM- modulated by an inverter 3, and the AC voltage is supplied to a load 8. The midpoint potential of the DC potential is produced by splitting-into-two capacitors 4 and 5 inserted in the DC voltage circuit, and a grounding resistor 9 is inserted between its midpoint potential and the ground. Moreover, grounding is detected by a grounding detector 6 arranged in series to the grounding resistor 9. Since no resistors are used in the DC voltage circuit, in this way, no resistor loss is produced. Accordingly, the system efficiency is improved. |
