| 摘要 |
PURPOSE:To prevent the fault of IGBT by adding voltage between the collector and emitter of the IGBT in the condition that negative potential is added to the gate of the IGBT. CONSTITUTION:A battery 1 is closed with a contactor 5, and the three-phase inverter circuit 8 consisting of three pieces of arm modules 9 is controlled with a gate circuit 10. A semiconductor switch IGBT which constitutes an arm module 9 is protected with one or more overcurrent detecting circuits. This safety circuit has a gate voltage detecting circuit 12 which detects negative voltage being applied from the gate circuit 10 to the IGBT connected to the positive side or negative side of the arm module 9. When the start switch 13 of a vehicle is turned on, an element 20 judges that the output of the gate voltage detecting circuit 12 is L, and controls the current application of the contactor 5. Moreover, CT16 detects the full current of a motor and CTs 17-19 detect each currents. Hereby, the fault of the IGBT is prevented, and even with failure of one CT, the operation of is continued. |
