| 摘要 |
PURPOSE:To improve the reliability by a method wherein, when the voltage value or the recovery current value between the smoothing capacitors exceed the specified value, the functions of transistor inverter are temporarily incapacitated and when said values do not exceed the specified value, said functions are recovered. CONSTITUTION:When an AC motor 1 is in operation under normal conditions, the AC is supplied to the induction motor 1 through the intermediary of rectifier 2 and a transistor inverter 5. When the terminal voltage Vc of the smoothing capacitor C1 exceeds the specified value due to the increased recovery energy, the monitor circuit 13 makes all of the driving signals TAD1-TAD6 ''0'' turning all transistors TA1-TA6 constituting the transistor inverter 5 off. When the energy accumulated in the smoothing capacitor C1 is returned to the power supply through the intermediary of the recovery circuit 3 and the transistor inverter 5 may recover the inverter functions. |
