Motor driving system without electrolytic capacitor and control method and device of motor driving system

Abstract

The invention discloses a motor driving system without an electrolytic capacitor and a control method and device of the motor driving system. The method comprises the following steps of detecting an input AC voltage of the motor driving system in real time; calculating a current highest running frequency of a compressor motor according to the input AC voltage; and controlling the compressor motor according to the current highest running frequency. By the method, the current highest running frequency of the compressor motor is calculated according to the input AC voltage, the highest rotational speed of the compressor motor can be timely limited when the input AC voltage abruptly changes, so that the compressor motor is effectively prevented from being out of control or the motor driving system is effectively prevented from being damaged, and the compressor motor and the motor driving system are enabled to stably and reliably run.

Description

technical field [0001] The invention relates to the technical field of motors, in particular to an electrolytic capacitor motor drive system and its control method and device. Background technique [0002] With the improvement of consumers' energy-saving requirements for electromechanical products, permanent magnet synchronous motors with higher efficiency have been more and more widely used. [0003] The DC bus voltage of the conventional variable frequency drive is in a stable state, and the inverter part is relatively independent of the input AC voltage, so that the control of the inverter part does not need to consider the instantaneous change of the input AC voltage, which is convenient for the realization of the control method. However, this design method needs to be equipped with an electrolytic capacitor with a large capacitance, which increases the size of the drive and increases the cost. Moreover, the life of the electrolytic capacitor is limited, and its effectiv...

AI Technical Summary

Problems solved by technology

[0005] However, since the capacitance of film capacitors or ceramic capacitors is very small, usually only 1%-2% of the capacitance of conventional high-voltage electrolytic capacitors, when the input AC voltage changes suddenly, the DC bus voltage will also change accordingly. If the motor cannot be controlled in time, the motor will be out of control or the electric control will be damaged.

For example, when the compressor of the air conditioner is running at high speed, if the input AC voltage drops, it will not be able to output enough torque due to the low DC bus voltage, which will cause the compressor to lose step, and even damage the inverter part, such as IPM ( Intelligent Power Module, intelligent power module)

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