| 摘要 |
PURPOSE:To make it possible to perform protection during forced driving by separating overcurrent detecting means by a valve current and a current of a regenerative current element and separating the valve overcurrent detection into two stages. CONSTITUTION:A three-phase bridge circuit is constituted by respectively 6 semiconductor valves V1 to V6 and D1 to D6 comprising IGBT and its feedback diodes. An overcurrent detection resistor R1 is provided between a common connection point of emitters of IGBT (V4, V6, V2) at row side and the ground, and also an overcurrent detection resistor R2 is provided between the common connection point of anodes of feedback diodes (D4, D6, D2) at law side. A valve of each phase is switching controlled by a control circuit 11, and a three-phase motor 13 is driven and controlled from an AC output point between valve connections at each phase. A generated voltage at the motor is fed back to a control circuit 11 and controlled. Also, detected values from overcurrent detection resistors R1 and R2 are supplied to the control circuit 11 and the control signal for protection is created at the control circuit 11. |
