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Three-phase digital phase-locked loop and phase lock method

A digital phase-locked loop and trigonometric function technology, applied in the field of phase-locked loops, can solve the problems that the phase-locked loop cannot track the phase of the power grid normally, and achieve the effect of simple structure and easy implementation

Inactive Publication Date: 2014-11-19
HEBEI UNIVERSITY
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] One of the purposes of the present invention is to provide a three-phase digital phase-locked loop to solve the problem that the existing phase-locked loop cannot normally track the grid phase when the three-phase grid is unbalanced

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  • Three-phase digital phase-locked loop and phase lock method

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Embodiment 1

[0066] Embodiment 1: A three-phase digital phase-locked loop.

[0067] Such as figure 1 As shown, the three-phase digital phase-locked loop provided by the present invention includes a Clark transformation unit 1, a Park transformation unit 2, a second-order generalized integrator (Second Order Generalized Integra, SOGI) 3, a subtractor 4, a PI controller 5, a local Synchronization signal generation unit 6 and trigonometric function table memory 7.

[0068] Clark transformation unit 1 is connected to Park transformation unit 2, and Clark transformation unit 1 collects the three-phase grid voltage u a , u b , u c , voltage u a The corresponding phase is θ (θ=ωt), and the voltage u b The corresponding phase is (θ-120°), the voltage u c The corresponding phase is (θ+120°), and the three-phase grid voltage is equivalently synthesized into a rotation vector with value V and angular frequency ω. Clark transformation unit 1 converts the three-phase grid voltage u represented b...

Embodiment 2

[0093] Embodiment 2, a three-phase digital phase-locking method.

[0094] refer to figure 1 , the three-phase digital phase-locking method provided by the present invention comprises the following steps:

[0095] a. Clark transformation unit 1 collects three-phase grid voltage u a , u b , u c And carry out Clark transformation to get the α-axis component u in the two-phase stationary coordinate system α and the β-axis component u β .

[0096] b, Park transformation unit 2 receives the local synchronization signal phase θ output by the trigonometric function table memory 7 0 The sine and cosine values ​​of , and the α-axis component u in the two-phase stationary coordinate system α and the β-axis component u β Perform Park transformation to obtain the q-axis component u in the two-phase rotating coordinate system q .

[0097] The trigonometric function table memory 7 outputs the sine and cosine values ​​of m groups of discrete, different-angle local synchronous signal...

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Abstract

The invention provides a three-phase digital phase-locked loop and a phase lock method. The three-phase digital phase-locked loop comprises a Clark conversion unit, a Park conversion unit, a second-order generalized integrator, a subtracter, a PI (Proportional Integral) controller, a local synchronizing signal generation unit and a trigonometric table storage. According to the three-phase digital phase-locked loop and the phase lock method, an output uq of the Park conversion unit is taken as an input v of the second-order generalized integrator, a center frequency of the second-order generalized integrator is 100 Hz, when a three-phase power grid is unbalanced, an output v' of the second-order generalized integrator is second harmonic sin2omegat in a negative sequence component, a difference between the uq and the v' is obtained by adopting the subtracter, so that the interference of the second harmonic is eliminated, and thus the phase of the power grid can be normally tracked by the three-phase digital phase-locked loop. A standard frequency signal is generated by adopting a crystal oscillator, and a local synchronizing signal of 50 Hz is formed through frequency division, so that the phase-locked loop does not need to track the frequency of the power grid and only tracks the phase.

Description

technical field [0001] The invention relates to a phase-locked loop, in particular to a three-phase digital phase-locked loop and a phase-locked method. Background technique [0002] In some power electronic equipment associated with the three-phase power grid, it is very important to obtain the real-time fundamental phase of the three-phase power grid. The automatic closed-loop control system that keeps synchronization with the frequency is widely used and can be used to track the grid phase in the control process of power electronic equipment. [0003] The three-phase voltage of the three-phase power grid will become unbalanced under instantaneous faults or under certain circumstances. This unbalanced three-phase voltage can be expressed as a collection of a series of unbalanced harmonic components. Generally, the three-phase voltage can be expressed as a collection of positive sequence components, negative sequence components and zero sequence components. For the distri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/08
Inventor 陆原汪周玮郭素兵王少龙魏大鹏
Owner HEBEI UNIVERSITY
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