Inverter and inverter topology

Abstract

The embodiment of the invention provides an inverter and an inverter topology, and aims to solve the problems of potential drift and fluctuation of the neutral point of a three-level inverter. The inverter comprises a positive direct-current bus, a negative direct-current bus, the three-level inverter, a detection circuit and a balance circuit, wherein the detection circuit is used for detecting the voltage difference between the voltage of a first direct-current bus and the neutral point, and outputting a first driving signal, a second driving signal, a third driving signal and a fourth driving signal to the balance circuit through each port of the detection circuit; and the balance circuit is used for connecting the first direct-current bus with the neutral point when the first driving signal is received through the fourth port of the balance circuit, disconnecting the first direct-current bus from the neutral point when the third driving signal is received through the fourth port of the balance circuit and the fourth driving signal is received through the fifth port of the balance circuit, and connecting another direct-current bus with the neutral point when the second driving signal is received through the fifth port of the balance circuit.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to an inverter and an inverter topology. Background technique [0002] The three-level inverter has the characteristics of high withstand voltage level, low voltage stress, and low voltage and current distortion rate. Traditional three-level inverters can be divided into diode clamped, capacitor clamped and level The diode clamping type has a simple structure and is widely used. [0003] However, in a three-level inverter, since two capacitors are connected in series between the positive and negative DC bus bars, the point where these two capacitors are connected is the neutral point. Under ideal conditions, the voltage of the neutral point is The average value of the sum of the voltages, however, when the capacitance of the two capacitors is different, the voltage at the neutral point will drift. In addition, the disturbance of the control system or the circulation will...

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Problems solved by technology

[0003] However, in a three-level inverter, since two capacitors are connected in series between the positive and negative DC bus bars, the point where these two capacitors are connected is the neutral point. Under ideal conditions, the voltage of the neutral point is The average value of the sum of the voltages, however, when the capacitance of the two capacitors is different, the voltage at the neutral point will drift

In addition, the disturbance of the control system or the disturbance of the circulation will also cause the voltage of the neutral point to drift or fluctuate

[0004] So far, a variety of algorithms have been proposed for the potential drift and fluctuation of the neutral point of the diode-clamped three-level inverter, but most of them use the method of adjusting the positive and negative redundant small vectors, and these algorithms The effect of solving this problem is closely related to the power factor, modulation degree and modulation strategy of the system. Therefore, in order to solve the problem of drift and fluctuation of the potential of the neutral point, it may be necessary to sacrifice other aspects of the performance of the system, for example, the total output of the system Harmonic distortion (THD, Total Harmonic Distortion), switching loss of switching devices in the system, etc., have led to the application of a method to solve the problem of drift and fluctuation of neutral point potential by means of adjusting positive and negative redundant small vectors range is limited

[0005] To sum up, the potential of the neutral point of the existing three-level inverter will drift and fluctuate, and the prior method cannot solve this problem well

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