Three-phase electric power converter, and control device and control method of three-phase alternating current motor

Abstract

When a third harmonic (52) applied to an output voltage instruction (51) modulated by a PWM is showed in a motor (12) terminal, based on a resistance value (R) of an earthling resistor (10) of a main circuit of a phase inverter device (8), delayed earthling static capacitor (c) applying a wire (cable) of the power to the motor (12), applying the third harmonic (802) with the phase exceeding the retardation to a sine wave (51) of the output voltage instruction. Therefore, a control device that covers the large voltage power inverter by a same voltage resisting semiconductor switching element, in particular a control device of the power inverter for motor drive that reduces peak value of the voltage to ground of the motor terminal, lightens deterioration of the motor insulating material.

Description

technical field [0001] The invention relates to a control device and a control method of a three-phase power converter, and a drive device and a drive method of a three-phase AC motor. In particular, it relates to a control device, a control method, a drive device, and a drive method suitable for driving a three-phase AC motor through a grounded main circuit through a resistor and through an electric wire (cable) having an electrostatic capacitance to the ground. Background technique [0002] As disclosed in Non-Patent Document 1, the deterioration speed of the insulating material of the motor largely depends on the peak value of the voltage applied to the ground of the winding. [0003] Therefore, Patent Document 1 discloses a technique of reducing the voltage by adding and subtracting the third harmonic to the voltage command value (modulated wave) of each phase in order to make the fundamental wave component larger than the peak value of the output voltage. command peak....

AI Technical Summary

Problems solved by technology

However, on the path where the third harmonic is applied to the motor terminals, there are grounding resistors of the main circuit of the power converter and electrostatic capacitances to ground of cables connecting the power converter and the motor.

Therefore, there will be a phase delay of the time constant determined by the product of the two for the sine wave voltage, and it can be seen that the waveform after the synthesis of the sine wave voltage and the third harmonic is not symmetrical. Therefore, the peak value of the ground voltage of the motor terminal raised

[0009] On the other hand, as disclosed in Non-Patent Document 1, the deterioration speed of the insulating material of the motor largely depends on the peak value of the voltage applied between the winding and the ground, so the life is shortened.

Considering this, in order to achieve insulation strengthening, there is a disadvantage of high manufacturing cost

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