Electromotor diver and compressor diver

Abstract

This invention claims an electromotor driver and compressor driver loading the motor driver. The motor driver makes the capacitor smoothing the commutated direct voltage of alternating current power be small capacity or do not be set. It realizes small size, light weight and low cost, furthermore, it can reduce higher harmonic current of input current effectively. The electromotor driver comprises a rectifying unit (3) for rectifying the AC voltage from AC supply to DC voltage, an inverter main circuit part (6) for transforming the DC voltage output by the rectifying unit (3) to AC voltage and applying the AC voltage to the electromotor (5); and a control unit (10) for controlling the voltage from the inverter main circuit part (6)applied to the electromotor (5), wherein the control unit (10) is provided with an output voltage limiting unit (23) for limiting the voltage applied to the electromotor (5) to let the scalar value of the voltage applied to the electromotor below the fixed maximum voltage output by the rectifying unit (3) and feed the voltage limitation of the output voltage limiting unit (23) to the control unit (10).

Description

technical field [0001] The present invention relates to a motor drive device for driving a motor, and a compressor drive device equipped with the motor drive device. Background technique [0002] A conventional motor drive device rectifies an AC power supply, smoothes the rectified DC power with a smoothing capacitor, and supplies power to a motor through an inverter. In the case of such a structure, a smoothing capacitor is required, and this smoothing capacitor becomes a factor of an increase in size and cost. However, when the smoothing capacitor is removed, it can be seen that the rectified DC voltage will cause pulsation synchronous with the AC power supply, which will have adverse effects on the motor such as torque ripple and efficiency deterioration. [0003] Therefore, in order to reduce the bad influence of the DC voltage pulsation on the motor without adding the smoothing capacitor, there is a technique of advancing the phase of the motor (for example, refer to P...

AI Technical Summary

Problems solved by technology

[0022] However, these motor drive devices need to narrow the operating range to a variable speed range that can drive the motor and reduce the harmonic current of the input current

[0023] Therefore, when it is intended to be applied to a system such as an air conditioner with a wide variable speed range, there is a problem that the above-mentioned limitation occurs.

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