| 摘要 |
PROBLEM TO BE SOLVED: To provide a surge voltage suppressing device, which is capable of completely suppressing surge voltages, even when only a simple circuit is added to the device, and can prolong the service life of the insulator of an AC motor. SOLUTION: A surge voltage suppressing device suppresses surge voltages generated in a motor driving device, in which the output terminal of a voltage type pulse width modulation(PWM) inverter 1 is connected to the input terminal of an AC motor 2 through relatively long cables 3. Damping circuits, each composed of a parallel circuit of a resistor 12 and inductor 11, are connected in series with the output terminal of the inverter 1, and at the same time, the resistance values of the resistors 12 and inductance values of the inductors 11 are decided from the inductance values and stray capacitance values of the cables 3, so that the damping circuits absorb the surge voltages. |
