A diode-clamped three-level inverter common-mode voltage suppression method

Abstract

A common-mode voltage suppression method suitable for a diode-clamped three-level inverter is characterized in that the method removes positive small vectors from the vectors synthesized by the output voltage, and maintains the neutral point voltage balance at the same time. According to the cell number of the sector where the inverter needs to output voltage, select the basic space vector, including zero vector, transition small vector, medium vector and large vector. In order to control the neutral point voltage balance, two negative small vectors with a mutual difference of 120 degrees from the transition small vector are introduced as the first additional small vector and the second additional small vector. According to the deviation of the three-phase current and the neutral point voltage corresponding to the transitional small vector, the first additional small vector and the second additional small vector, the neutral point voltage control is divided into three working conditions, and the control of the neutral point voltage for each working condition is calculated ability, the one with the greatest control ability is the optimal working condition. Calculate the final action time of each vector according to the selected optimal working condition, control the on-off of power electronic devices, and reduce the output common-mode voltage amplitude to 1 / 6 of the DC bus voltage.

Description

Technical field [0001] The invention relates to a common mode voltage suppression method suitable for a diode clamped three-level inverter. Background technique [0002] With the emergence of energy and environmental issues, countries around the world are turning more attention to renewable energy. Among them, wind power has become the current renewable energy power generation method with the most large-scale development conditions and commercial development prospects. In wind power generation, PWM inverters are required to process electric energy. Among them, four-quadrant converters composed of diode-clamped three-level inverters have the advantages of high energy conversion efficiency, relatively simple control, and low du / dt. Adopted, but there are some negative effects in its application. The typical problem is the high frequency common mode voltage generated by the inverter. [0003] The high-frequency common-mode voltage induces high-frequency shaft voltage on the generator...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcoming that the existing common-mode voltage suppression method cannot control the neutral point voltage balance, and propose a method for reducing the output common-mode voltage of the diode-clamped three-level inverter. At the same time, it can control the neutral point voltage balance

Images