Software phase locked loop improving method

A technology of software phase-locked loop and grid voltage, applied in the field of phase-locked loop, can solve problems such as difficulty in obtaining accurate signal delay, poor phase-locking effect, etc.

Active Publication Date: 2015-03-25
TIANJIN RES INST OF ELECTRIC SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The purpose of the present invention is to overcome the deficiencies of the prior art, provide an improved method for the software phase-locked loop, and solve the problem that the traditio

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Embodiment Construction

[0041] Embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings.

[0042] A method for improving the software phase-locked loop, comprising the following steps:

[0043] Step 1. Sampling the grid voltage and obtaining the voltage component u in the two-phase coordinate system through Clarke transformation α , u β , its calculation formula is as follows:

[0044] u α = 1 3 ( u ab - u ca )

[0045] u β = 1 3 ( u ab - u ca ) + 2 3 ...

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Abstract

The invention relates to a software phase locked loop improving method. The software phase locked loop improving method is characterized by comprising the following steps that sampling is carried out on power grid voltage, and voltage components ualpha and ubeta under a two-phase coordinate system are obtained through Clarke conversion; accurate delayed signals ualpha-D and ubeta-D of the voltage components ualpha and ubeta are calculated through a weighted average method; power grid voltage positive-sequence components u and u are extracted according to a delayed signal cancellation principle; rotation axis conversion is carried out on the power grid voltage positive-sequence components u and u so as to obtain u (n) and u (n), wherein n represents the current nth control period; the frequency of the power grid voltage is calculated; digital integration is carried out on the frequency of the power grid voltage so as to obtain a power grid voltage phase angle used for calculation of rotation axis conversion, and closed loop feedback is formed. The weighted average method of two sets of delayed signals is adopted to approach the expected delayed signals, and therefore signal delaying is more accurate, direct current offset and fluctuation in the phase locked angle and amplitude are effectively restrained, accuracy of power grid fundamental wave voltage phase locking is improved, and the method can be widely applied on the occasions high in requirement for the PLL response speed.

Description

technical field [0001] The invention belongs to the technical field of phase-locked loops, in particular to a method for improving software phase-locked loops by using a signal delay cancellation (Delayed Signal Cancellation, DSC) technology. Background technique [0002] Voltage source grid-connected converters are widely used in the fields of active filtering, UPS uninterruptible power supply, variable frequency drive and renewable energy power generation, and are an important type of power electronic conversion device. It is very important to quickly and accurately obtain the positive sequence information of the grid voltage fundamental frequency for the control of such devices, and this task is usually realized by software phase-locked loop (Phase Locked Loop, PLL) technology. [0003] There are many types of software phase-locked loops. At present, the most commonly used one in the three-phase voltage source grid-connected converter is the Synchronous Reference Frame PL...

Claims

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Application Information

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IPC IPC(8): H03L7/08
Inventor 金雪峰宋鹏田凯姜一达王达蔡保海
Owner TIANJIN RES INST OF ELECTRIC SCI
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