A method for controlling the bus voltage low-voltage region of a small-capacitance motor drive system

Abstract

The invention discloses a bus voltage low-voltage region control method for a small-capacitance motor driving system, which comprises the following steps: S010, performing speed estimation, speed estimation of the press being performed according to the phase current and the bus voltage of the detection press; S011, sampling the real-time bus voltage; S012, judging the voltage threshold value, looking up the table to find out the corresponding bus voltage threshold value according to the speed estimated in step S010, and performing correction; and S013, performing mode selection, comparing thereal-time bus voltage sampled in step S011 with a voltage threshold, and selecting a control mode, the control mode including an inverter control mode and a rectifier control mode. The control methodof the invention has the advantages of simple hardware circuit of the control system and low cost. The method can prevent the current loop from losing control and the bus voltage from being charged backward by the back electromotive force of the motor in the low voltage region, and can also control the stability of the bus voltage, so as to remarkably improve the stability of the system and the grid side current input power factor.

Description

technical field [0001] The invention relates to the technical field of motor drive control, in particular to a method for controlling a bus voltage low-voltage area of ​​a small-capacitance motor drive system. Background technique [0002] In recent years, inverter air conditioners have been popularized, because inverter air conditioners can change the speed of the compressor in a timely and convenient manner, so it can control the fluctuation of room temperature to be small, the indoor comfort is better, and it is more energy-saving. [0003] The DC bus of the traditional variable frequency drive system uses a large electrolytic capacitor to stabilize the bus voltage. Generally, the electrolytic capacitor is several hundred uF, and the use of a large electrolytic capacitor can realize power decoupling. However, large electrolytic capacitors have some defects, such as electrolytic capacitors are large in size, easy to generate heat, and have a low lifespan, which directly de...

AI Technical Summary

Problems solved by technology

Although the small capacitor drive system has this advantage, there are also some difficulties in regulating and controlling the bus voltage

Due to the single-phase rectification and the very small bus capacitance, the DC bus voltage is no longer DC, and the bus voltage waveform is similar to a half-sine wave at heavy load and high speed, and the bus voltage will have a low-voltage area or even close to zero, but when the motor is running At medium and high speeds, the counter electromotive force is relatively high, but the bus voltage is too low and the available voltage is not enough, which will cause the current loop regulation ability to lose its effect, resulting in a short-term instability of the system, which not only affects the stable phase of the motor control, but also affects the grid side. Current power factor, so it is necessary to control the bus voltage in the low-voltage area

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