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Method for synchronization of three-phase parallel type inversion module

A technology of inverter module and parallel connection, which is applied in the synchronization field of three-phase parallel uninterruptible power supply system, which can solve the problems that are difficult to eliminate and cannot guarantee synchronization, and achieve the effect of eliminating high-frequency components

Active Publication Date: 2008-01-23
ZTE CORP
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Problems solved by technology

Due to the difference in power-on time and the drift of the crystal oscillator, the PWM (Pulse Width Modulation, Pulse Width Modulation) carrier of each inverter module will not be able to guarantee synchronization, resulting in high-frequency components, which are extremely difficult to eliminate in a distributed control parallel system

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  • Method for synchronization of three-phase parallel type inversion module
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  • Method for synchronization of three-phase parallel type inversion module

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Embodiment Construction

[0031] The invention includes three-phase phase-locking and carrier synchronization, the latter is used to further solve the high-frequency component of circulating current. Described below:

[0032] 1. Three-phase phase-locking method

[0033] In a three-phase AC system, the abc three-phase quantities correspond to a rotating space vector, and each phase component is equal to the projection of the vector on the coordinate axis, as shown in Figure 1. The rotational velocity of the space vector is equal to the angular velocity of the three-phase quantity, corresponding to its frequency. The phase angle of the space vector, that is, the angle between it and the a-axis is equal to the phase angle of the a-phase voltage, corresponding to the phase of the three-phase quantity. So the phase locking of the three-phase quantity is equivalent to the tracking problem of the output voltage space vector to the tracking source voltage space vector.

[0034] The rotation speed of the spa...

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Abstract

A three-phase parallel-connection reversal module synchronization method is provided. In a system, each reversal module realizes free competition by seizing a bus to confirm a host machine and an auxiliary machine. Wherein, the main machine and the auxiliary machine respectively take a bypass voltage and a main machine output voltage as a phase locking tracking source. Each module samples a three-phase tracking source and a three-phase output voltage and calculates frequency of the tracking source voltage and the output voltage, frequency difference and phase difference. Based on the frequency difference between the tracking source and the output voltage, look-up length of a PWM modulation sine wave is adjusted to gradually fix frequency of the tracking source. And then, the look-up length of the PWM modulation sine wave is slightly adjusted according to the phase difference between the tracking source and the output voltage to reduce phase difference between them and fix the phase. A synchronous pulse is transmitted at a zero passage of a main counter through the main machine. The auxiliary machine captures the pulse and sends the pulse to a rectification method of the main counter for carrier wave synchronization. The present invention solves a problem of three-phase locking and eliminates high-frequency component in circulating currents.

Description

technical field [0001] The invention relates to the field of three-phase modular parallel inverter power supply, in particular to the synchronization of three-phase parallel uninterruptible power supply systems. Background technique [0002] At present, the AC power supply mode is developing from centralized to distributed and full-featured. A power system composed of multiple inverter modules connected in parallel has become a promising engineering application scheme. This parallel redundant system has the following advantages: reliable operation, wide power range, extremely high system maintainability, and when a module fails, it can be easily replaced or repaired by hot swapping. The technical key is the synchronization of each inverter module, that is, the output voltage of each inverter module should meet the same amplitude, same frequency and same phase, so as to achieve the requirements of equal load sharing and zero circulating current. [0003] The circulating cur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/40
Inventor 杨国顺孙文焕
Owner ZTE CORP
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