A method of overcurrent protection for small-capacity bus capacitor drivers

Abstract

The invention relates to an overcurrent protection method for a small-capacity bus capacitor driver, which belongs to the technical field of motor equipment. Its method step 1: when the permanent magnet synchronous motor M is running normally, the microcontroller U detects and records the time of any two-phase current adjacent to the zero crossing point in real time through its internal counter, and expresses this time with D; step 2: when the permanent magnet synchronous motor M When the synchronous motor M is over-current or needs to be shut down in an emergency, the microcontroller U detects the current status of the A, B, and C phases through the current sensor L, and controls the switching status of the switching tubes Q1~Q6; Step 3: From the motor M Counting from the time when overcurrent or emergency needs to be shut down, turn off the conduction switch tube at the time D2, said D2=3D / 2-D1, to realize the overcurrent protection of the motor driver. The invention can significantly reduce or even eliminate the voltage pumping of the motor drive bus capacitor, and protect the safety of the drive in emergency situations such as overcurrent. After adopting the overcurrent protection method of the present invention, the boosted voltage of the bus capacitor can be reduced to less than 10% of the original value.

Description

technical field [0001] The invention belongs to the technical field of electrical equipment. Background technique [0002] Due to the high power density and excellent control characteristics of permanent magnet synchronous motors, they are widely used in transportation, aerospace, household appliances and other fields. However, permanent magnet synchronous motors require dedicated drives for control. Currently commonly used drivers generally adopt an AC-DC-AC main circuit design scheme or a DC-AC design scheme directly powered by a DC source. No matter what design scheme is adopted, it is necessary to add a large-capacity electrolytic capacitor to the DC bus of the driver to suppress voltage fluctuations. Although electrolytic capacitors have the advantages of cheap price and high energy density, they have poor stability, low life, are easily affected by external temperature, and are prone to generate inrush current during power-on. Reducing the use of electrolytic capaci...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide an overcurrent protection method for a small-capacity bus capacitor driver, in order to solve the problem that the existing driver overcurrent protection method can only protect the safety of the permanent magnet synchronous motor, but cannot protect the safety of the driver, especially There is a problem that it cannot protect the driver with a small bus capacitor capacity

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