Surge voltage suppressor

Abstract

Semiconductor surge absorbing devices are connected individually between power lines for the U, V and W phases, which connect an inverter and a motor, and between the ground and the power lines. The absorbing devices are adapted to be energized to clamp voltages between opposite terminals thereof when the voltages are higher than a given value.

Description

technical field [0001] The present invention relates to a surge voltage suppression device for controlling a surge voltage generated in a motor when the motor is controlled by an inverter PWM. Background technique [0002] In the case where the inverter PWM (pulse width modulation) is used to control the motor for drive control, it is the switching of switching elements such as power transistors controlled by PWM, which generates AC voltage from DC voltage and applies the AC voltage to each phase of the motor. On the coil, to drive and control the motor. [0003] In the case of PWM control of such a motor, since the switching element ON / OFF is used to control the DC voltage, if the power line connected to the motor is long, the inductance of the power line becomes large, and the 3-phase in the motor Surge voltages are generated between the coils and between the 3-phase coils and ground. There is a problem that the insulation between the three-phase coils in the motor and b...

AI Technical Summary

Problems solved by technology

[0006] However, in the method of suppressing the surge voltage by using a filter composed of a reactor and a capacitor, there is a problem that the space required for installing the filter device needs to be enlarged, so the cost is high.

[0007] In addition, in the method disclosed in the aforementioned Japanese Patent Laid-Open No. 8-23682 that absorbs the surge voltage into the capacitor through the three-phase diode bridge, there is a problem that current always flows through the resistor, and energy is consumed in vain.

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