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Method for restraining parallel-connection circulating currents of three-phase four-leg inverters on basis of third-harmonic injection

A three-phase four-bridge, sub-harmonic technology, applied in the direction of converting AC power input to DC power output, output power conversion devices, electrical components, etc., can solve problems such as aggravation of circulating current problems

Inactive Publication Date: 2013-03-27
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

In practice, the main circuit parameters of each module and the switching time of the main power tube cannot be consistent, and the asymmetry of the third harmonic caused by these factors will inevitably lead to the aggravation of the circulation problem

Method used

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  • Method for restraining parallel-connection circulating currents of three-phase four-leg inverters on basis of third-harmonic injection
  • Method for restraining parallel-connection circulating currents of three-phase four-leg inverters on basis of third-harmonic injection
  • Method for restraining parallel-connection circulating currents of three-phase four-leg inverters on basis of third-harmonic injection

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Embodiment Construction

[0014] attached figure 1 It is a schematic diagram of the control strategy structure of the three-phase four-leg inverter parallel connection circulating current suppression method with third harmonic injection, and its control circuit part is mainly composed of a three-phase inductor current sharing controller (1), a neutral current reference signal generation controller ( 4), the third harmonic generator (5) (6) (7), and several main parts. Among them, the three-phase inductor current sharing controller firstly compares the fed-back three-phase output voltage with the reference voltage, and obtains the current reference signal of the three-phase current loop through the proportional integral link composed of the operational amplifier, and then obtains the three-phase current signal of each inverter module through LEM sampling. The feedback value of the phase inductance current is compared with the shared current reference signal, and the modulation signal of the first three ...

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Abstract

The invention discloses a control strategy for restraining circulating currents of three-phase four-leg inverters on the basis of third-harmonic injection, and provides a method for restraining circulating currents of three-phase four-leg inverters on the basis of third-harmonic injection. The method includes that three-phase current reference signals outputted by voltage loops are synthesized into a zero-sequence current reference signal (4) on the basis (1) of parallel-connection voltage and current double-loop control of the three-phase four-leg inverters for a parallel-connection topology of two three-phase four-leg inverter modules (2) and (3), and error amplifiers track the zero-sequence current reference signal for a mid-line inductive current in a fourth leg of each module, so that mid-line currents of the two three-phase four-leg inverters are shared, and purposes of restraining the circulating currents of the mid-line currents, protecting power tubes and improving the efficiency of each inverter are achieved; and output signals of current loops of the two modules are synthesized to form two third-harmonic signals (5), the two third-harmonic signals (5) are added to obtain a sum (6), an average value (7) of the sum is used as a common third-harmonic signal (8) for being injected into three-phase and mid-line modulation signals of the two inverter modules, zero-sequence modulation components in the third-harmonic signals are eliminated, and the instantaneous zero-sequence circulating currents caused by factors such as inconsistency of parameters of a main circuit filter and inconsistency of switching time of switching tubes are restrained. The method has the outstanding advantages that the circulating currents of the mid-line currents are effectively restrained; control loops are simple; and third-harmonic injection of the parallel-connection inverters is unaffected, and the direct-current voltage utilization rate is increased.

Description

Technical field: [0001] The invention relates to a method for suppressing parallel circulation of three-phase four-bridge inverters based on third harmonic injection, which belongs to the control technology in electric energy conversion devices. Background technique: [0002] At present, in distributed power generation systems such as new energy, aircraft and electric vehicles, three-phase four-leg inverters controlled by SPWM are widely used for their advantages of three-phase decoupling, asymmetric load capacity, and short-circuit current limiting. With the continuous improvement of the power level of power electronic equipment, the inverter parallel technology stacks multiple inverter modules to jointly provide power to the load, which has become the preferred choice for inverter expansion and reduction of switch tube current stress. [0003] Because the parallel connection of inverters is different from the parallel connection of traditional DC-DC converters, when multip...

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Application Information

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IPC IPC(8): H02M7/5387H02M1/08
Inventor 陈轶涵龚春英韦徵邓翔陈杰
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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