Modified modulated wave acquisition method and model predictive control method for single-phase cascaded H-bridge rectifier

Patent metadata

Field	Value
Publication number	US-11159100-B2
Application number	US-202016996927-A
Country	US
Kind code	B2
Filing date	Aug 19, 2020
Priority date	Feb 25, 2020
Publication date	Oct 26, 2021
Grant date	Oct 26, 2021

Abstract

A modified modulated wave acquisition method includes: obtaining a modulated wave uaba; calculating a difference between the given value iNq* and the actual value iNq of the q-axis component of a grid side current, inputting the result to a proportional integral (PI) controller, and multiplying an output of the PI controller by cos ωt to obtain a modulated wave offset Δuaba; and calculating a difference between the modulated wave uaba and the modulated wave offset Δuaba to obtain a modified modulation wave uaba′, where ωt is a grid voltage phase in a sinusoidal case. The MPC method for a single-phase cascaded H-bridge rectifier includes: obtaining the modified modulated wave uaba′, where the component iNq* is 0; and replacing the modulated wave uaba with the modified modulated wave uaba′ to perform MPC for the single-phase cascaded H-bridge rectifier.

First claim

What is claimed is:

1. A modified modulated wave acquisition method, comprising:
obtaining a modulated wave u aba ;
calculating a difference between a given value i Nq * and an actual value i Nq of the q-axis component of a grid side current, and inputting a result of the difference to a proportional integral (PI) controller;
multiplying an output of the PI controller by cos ωt to obtain a modulated wave offset Δu aba ; and
calculating a difference between the modulated wave u aba and the modulated wave offset Δu aba to obtain a modified modulation wave u aba ′, wherein ωt is a grid voltage phase in a sinusoidal case.

2. The modified modulated wave acquisition method according to claim 1 , wherein a method for obtaining a proportional coefficient of the PI controller and an integral coefficient of the PI controller comprises:
after setting the integral coefficient to 0, gradually increasing the proportional coefficient until the component i Nq of the instantaneous grid-side current on the q-axis oscillates, then gradually reducing the proportional coefficient until the component i Nq of the instantaneous grid-side current on the q-axis does not oscillate, and updating the proportional coefficient of the PI controller to a current proportional coefficient; and
setting an initial value of the integral coefficient based on the proportional coefficient of the PI controller, gradually reducing the integral coefficient until the component i Nq of the instantaneous grid-side current on the q-axis oscillates, then gradually increasing the integral coefficient until the component i Nq of the instantaneous grid-side current on the q-axis does not oscillate and i Nq equals i Nq *, and updating the integral coefficient of the PI controller to the current integral coefficient.

3. The modified modulated wave acquisition method according to claim 1 , wherein a method for obtaining the modulated wave u aba comprises:
obtaining voltage components u abd and u abq of an input-side voltage u ab of a rectifier in a dq coordinate system; and
performing direct-quadrature (d-q) inverse transformation on the voltage components u abd and u abq to obtain the modulated wave u aba .

4. The modified modulated wave acquisition method according to claim 2 , wherein a method for obtaining the modulated wave u aba comprises:
obtaining voltage components u abd and u abq of an input-side voltage u ab of a rectifier in a dq coordinate system; and
performing d-q inverse transformation on the voltage components u abd and u abq to obtain the modulated wave u aba .

5. The modified modulated wave acquisition method according to claim 3 , wherein a method for obtaining the voltage components u abd and u abq comprises:
obtaining a relationship between a voltage and a current on an AC side of the rectifier in a stationary αβ coordinate system according to a topology of a rectifier circuit and Kirchhoff s voltage law;
obtaining an expression of the voltage components u abd and u abq of the input-side voltage u ab of the rectifier in the dq coordinate system according to the relationship between the voltage and the current on the AC side of the rectifier; and
converting the expression of the voltage components u abd and u abq of the input-side voltage u ab of the rectifier in the dq coordinate system into an expression containing a switching period T s to obtain the voltage components u abd and u abq .

6. A model predictive control (MPC) method for a single-phase cascaded H-bridge rectifier, comprising: obtaining a modified modulated wave u aba ′ by using the method according to claim 1 , wherein a component i Nq * is 0; and replacing a modulated wave u aba with the modified modulated wave u aba ′ to perform MPC for the single-phase cascaded H-bridge rectifier.

7. The model predictive control (MPC) method for a single-phase cascaded H-bridge rectifier according to claim 6 , wherein
a method for obtaining a proportional coefficient of the PI controller and an integral coefficient of the PI controller comprises:
after setting the integral coefficient to 0, gradually increasing the proportional coefficient until the component i Nq of the instantaneous grid-side current on the q-axis oscillates, then gradually reducing the proportional coefficient until the component i Nq of the instantaneous grid-side current on the q-axis does not oscillate, and updating the proportional coefficient of the PI controller to a current proportional coefficient; and
setting an initial value of the integral coefficient based on the proportional coefficient of the PI controller, gradually reducing the integral coefficient until the component i Nq of the instantaneous grid-side current on the q-axis oscillates, then gradually increasing the integral coefficient until the component i Nq of the instantaneous grid-side current on the q-axis does not oscillate and i Nq equals i Nq *, and updating the integral coefficient of the PI controller to the current integral coefficient.

8. The model predictive control (MPC) method for a single-phase cascaded H-bridge rectifier according to claim 6 , wherein
a method for obtaining the modulated wave u aba comprises:
obtaining voltage components u abd and u abq of an input-side voltage u ab of a rectifier in a dq coordinate system; and
performing d-q inverse transformation on the voltage components u abd and u abq to obtain the modulated wave u aba .

9. The model predictive control (MPC) method for a single-phase cascaded H-bridge rectifier according to claim 8 , wherein
a method for obtaining the voltage components u abd and u abq comprises:
obtaining a relationship between a voltage and a current on an AC side of the rectifier in a stationary αβ coordinate system according to a topology of a rectifier circuit and Kirchhoff s voltage law;
obtaining an expression of the voltage components u abd and u abq of the input-side voltage u ab of the rectifier in the dq coordinate system according to the relationship between the voltage and the current on the AC side of the rectifier; and
converting the expression of the voltage components u abd and u abq of the input-side voltage u ab of the rectifier in the dq coordinate system into an expression containing a switching period T s to obtain the voltage components u abd and u abq .

Assignees

• Univ Southwest Jiaotong

Inventors

• Feng Xiaoyun
• Xiong Chenglin
• Mei Rong
• Song Shuang
• Song Zhiwei
• Huang Lu

Classifications

• H02M7/5387

  in a bridge configuration · CPC title

• H02M1/007

  Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826) · CPC title

• H02M1/0022

  the disturbance parameters being input voltage fluctuations · CPC title

• H02M7/539 Primary

  with automatic control of output wave form or frequency (H02M7/5375 - H02M7/5387 take precedence) · CPC title

• G05B17/02

  electric · CPC title