| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise of an electric motor by making a signal smoothed by a command calculating part a torque command to an inverter until a prescribed time has passed by turning off an overvoltage signal, and changing the torque command continuously when direct current voltage which rectifies alternating current power supply is in an overvoltage condition. SOLUTION: A torque command filter part 9 is fitted between a torque command value calculating part 8 and an inverter circuit 10 at the time of overvoltage. When an overvoltage signal is switched from OFF to ON or from ON to OFF, the output of the torque command value calculating part 8 which changes into a stepped condition is converted into a signal which changes smoothly in a preset period by the operation of the torque command filter part 9 at the time of overvoltage, from a torque command value at the time of overvoltage to a torque command value, and from the torque command value to an overvoltage torque command value, and is supplied into the inverter 10. In other words, the output signal of the torque command calculating part 8 changes smoothly at the time of overvoltage and stabilize the torque command value after the preset period has passed, thus preventing noise from occurring, which will not occur under normal usage. |
