| 摘要 |
PROBLEM TO BE SOLVED: To prevent the overvoltage of a multiplex power converter and at the same time reduce the voltage load to a specific switching element by independently determining the operation/non-operation of a chopper circuit that is provided for each capacitor so that a DC voltage for each capacitor of a power converter can be set within a predetermined range. SOLUTION: When a DC differential voltage is generated between DC smoothing capacitors 5 and 7 when a system fails, an upper chopper circuit 6 and a lower chopper circuit 8 are operated and the energy of the DC smoothing capacitors 5 and 7 is discharged if a first predetermined voltage is exceeded, based on the DC voltage detection signal of the DC smoothing capacitors 5 and 7 by an upper control circuit 13 and a lower control circuit 14. When the level becomes lower than a second predetermined level, operation is stopped. As a result, by allowing each different chopper current to flow to the upper and lower chopper circuits 6 and 8, the upper and lower DC voltage is controlled a given value or less and the overvoltage of power converters 1 and 2 is prevented, thus reducing the load of voltage to a switching element. |
