| 摘要 |
PURPOSE:To protect a main conversion element from surge voltage breakage, by a method wherein a surge voltage suppressing circuit composed of a diode and a capacitor is added. CONSTITUTION:AC power source voltage E2 is rectified and smoothed into DC power source voltage by a converter CNV2 and a smoothing capacitor 6, and further the DC voltage is converted reversely to necessary AC power source voltage by passing through an inverter INV2 and then supplied to an induction motor IM2. The inverter INV2 is constituted by units TU1-3 and provided with transistors TR7-12 as a main conversion element. In this case, diodes D4-D7 and capacitors C7-C8 are added as a surge suppressing circuit, thereby the surge voltage is stored in the capacitors C7-C8 and fed back to the power source voltage. Thereby the surge voltage is not applied to the transistors TR7-12. |
