A control method for unit modulation degree of inverter with frequency conversion and speed regulation and its application

Abstract

The invention provides a method for controlling the unit modulation degree of a variable frequency speed-adjusting inverter, which includes: unitizing the modulation degree: obtaining the target phase voltage component; determining the control pulse duty ratio of the DC bus step-down circuit; Limiting; generate step-down circuit drive pulses according to the duty cycle obtained after limiting; phase shift calculation caused by dead zone: determine the expected output voltage frequency of the inverter; determine the dead zone time of the inverter; obtain the expected output caused by the dead zone The voltage fundamental wave advances the phase shift; the fundamental wave phase shift compensation process: obtain the polar coordinate form of the target phase voltage component; rewrite the phase of the target phase voltage component; call the SVPWM or SPWM program in the permanent magnet synchronous motor control program to generate the inverter drive signal to Control permanent magnet synchronous motor. The invention realizes perfect phase control, is beneficial to the precise measurement of the rotor position of the PMSM, has simplified steps and clear logic, and can improve the control precision of the PMSM.

Description

technical field [0001] The invention relates to the technical field of frequency conversion and speed regulation, in particular to a method for controlling the unit modulation degree of a frequency conversion and speed regulation inverter and its application, which is used for precise power supply of frequency converters. Background technique [0002] The post-stage circuit of the frequency conversion speed control inverter is a voltage source inverter, which is widely used in industrial frequency conversion speed control, frequency conversion household appliances and other application fields. As a voltage source inverter (VSI) powered by DC voltage, the same bridge When the working state of the upper and lower power switches is switched, it is necessary to set a long enough dead time to prevent the short circuit of the DC power supply caused by the direct connection of the bridge arm and cause the power switch to be damaged by overcurrent. [0003] The addition of dead time...

AI Technical Summary

Problems solved by technology

[0003] The addition of dead time will cause some problems that deviate from the ideal modulation. So far, the main concerns of people are: (1) Under the same modulation degree, the effective value of the fundamental wave of the output phase voltage (or line voltage) drops, that is, the maximum voltage The utilization rate decreases; (2) The output phase voltage (line voltage) is distorted according to the average value of the switching cycle, that is, the actual output fundamental phase voltage (or line voltage) is distorted, causing motor current distortion and torque ripple;

But up to the present, also do not appear above-mentioned corresponding compensation method, also do not find explanation or report with similar technology of the present invention, and similar data both at home and abroad

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