Dead-zone compensation method of three-phase inverter

Abstract

The invention relates to control strategies of a three-phase inverter, and discloses a dead-zone compensation method of the three-phase inverter. The dead-zone compensation method of the three-phase inverter can effectively improve waveform distortion caused by a dead zone and reduce THD. The dead-zone compensation method is an off-line dead-zone compensation method and mainly comprises two parts including (1) accurate judgment on the inductive current polarity and (2) dead-zone compensation strategies under a, b and c coordinates according to a three-phase system. The accurate judgment on the inductive current fundamental wave polarity can further be divided into sampled inductive current polarity detection, electric current measurement circuit delay calculation and fundamental wave delay estimation caused by the dead zone, the inductive current fundamental wave polarity can be accurately obtained through the three steps, then the compensation strategies under the a, b and c coordinate system are adopted, therefore, extra delay caused by using a low pass filter is avoided, and compensation is turned to be simple and practical.

Description

technical field [0001] The invention relates to the control of a three-phase inverter, and discloses a dead zone compensation method of the three-phase inverter, which can effectively improve the output of the inverter and reduce THD. Background technique [0002] With the development of power electronics technology and micro-processing technology, AC speed regulation technology is also advancing rapidly. In order to make the voltage source inverter output a more ideal current waveform, the power electronic devices in the inverter must work at a higher switching frequency. In the commutation process of two power electronic devices in the same bridge arm of the voltage-type inverter, in order to prevent the DC bus voltage short circuit from burning out the power electronic devices, one power electronic device in the same bridge arm must be completely turned off. Another power electronics device can be turned on. In this way, the tube to be opened must be delayed for a perio...

AI Technical Summary

Problems solved by technology

However, the judgment of the polarity of the inductor current is not accurate, and the accuracy of compensation is not high.

[0011] The existing technology [2] discloses the use of software to realize dead zone compensation. This method does not need to add any hardware equipment, and is only implemented by software, so it is convenient to implement. However, this method does not analyze the action delay of the switch itself and the on-state voltage drop of the device. The effect of compensation needs to be improved

[0012] The existing technology [3] has obtained the polarity of the inductor current and compensated the zero current clamping effect, but it is relatively complicated and not easy to implement

[0013] In the general dead zone compensation method, most of the detected inductor current is directly used, but because the harmonic component in the inductor current is large, and the use of the current Hall will also bring a certain delay, so the directly detected inductor current is not accurate.

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