A dead zone compensation method for a three-level inverter

Abstract

A three-level inverter dead zone compensation method, involving the inverter switching strategy, the steps are as follows: divide the inverter output voltage to obtain a voltage of 0~3V; set the reference values ​​of two sets of voltage comparators U ref1 and U ref2 ;Configure the ePWM module and 3 CAP modules in the DSP processor; the input of the voltage comparator is the divided voltage and the reference voltage; configure the DSP processor ADC module; divide the inverter voltage vector diagram into 6 sectors, for The obtained two groups of duty cycles are screened, and the obtained two groups of voltage signals are screened to obtain the high-level duration and compensation time of the terminal voltage of one phase; calculate the distance between the midpoint potential and the middle potential of the output terminal voltage, and judge Current polarity; calculate the compensation voltage and add it to the target voltage to obtain the target voltage; implement the latest three-vector pulse width modulation strategy, and complete the compensation of the dead zone effect of the inverter; it has independent current detection, high precision, low cost, and wide application range Etc.

Description

technical field [0001] The present invention relates to an inverter switching strategy, in detail, it is a three-level inverter die that does not rely on current detection, is based on terminal voltage detection, considers midpoint potential fluctuations of three-level inverters, has low cost, and has a wide range of applications. Area Compensation Method. Background technique [0002] We know that, considering the switching delay of the power device, in order to prevent the bridge arm from passing through, the pulse width modulated voltage source inverter needs to insert a dead time. Although the dead time accounts for only a small fraction of the switching cycle, the accumulated voltage errors can lead to undesirable consequences such as current distortion, output torque ripple, and increased motor losses. The waveform sine degree of the three-level inverter is better than that of the two-level inverter, so it is widely used, but no matter what type of inverter is used, t...

AI Technical Summary

Problems solved by technology

Although the dead time accounts for only a small fraction of the switching cycle, the accumulated voltage error can lead to undesirable consequences such as current distortion, output torque ripple and increased motor losses

The waveform sine degree of the three-level inverter is better than that of the two-level inverter, so it is widely used, but no matter what type of inverter is used, the three-level T-type inverter or the diode-clamped three-level I-type inverter device, or what modulation method is used, the latest three-vector pulse width modulation (NTV-PWM), or the virtual space vector pulse width modulation (VSV-PWM), the performance of the motor will be greatly reduced due to the insertion of dead time

For current polarity judgment, due to the existence of PWM noise and current clamping phenomenon, it is difficult to use a current sensor to achieve accurate current detection in the current zero-crossing interval

For the acquisition of compensation time, most construction machinery does not perform compensation or uses a fixed compensation time for compensation when the motor output performance is not required, but it is not applicable to occasions with high motor performance requirements

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