CN-118801714-B - Dual-phase shift modulation method and system for three-level parallel inverter

CN118801714BCN 118801714 BCN118801714 BCN 118801714BCN-118801714-B

Abstract

The invention provides a three-level parallel inverter biphase shift modulation method and system, which are characterized in that a divided area where each phase modulation wave is located is obtained according to a three-phase modulation wave, a carrier correction angle of each phase is calculated through the area where each phase modulation wave is located, a total phase shift angle is obtained according to the carrier correction angle, a circulating phase shift angle and a carrier initial angle, a peak value of a common mode voltage difference is reduced or the residence time of a switching sequence generating the common mode voltage difference is reduced by reasonably arranging three-phase total voltage differences of switching states based on the added circulating phase shift angle, high-frequency circulating current inhibition is realized, a first phase shift comparison value and a second phase shift comparison value corresponding to an upper carrier wave and a lower carrier wave are obtained according to the total phase shift angle respectively, so that each phase voltage of the upper carrier wave and each phase voltage of the lower carrier wave are obtained, a carrier wave subsection phase shift process is simplified, and improvement of a parallel three-level inverter system output current ripple and circulating current inhibition are realized.

Inventors

XING XIANGYANG
Fang Cunyu
LIU XI
LIU CHANG

Assignees

山东大学

Dates

Publication Date: 20260505
Application Date: 20240621

Claims (8)

1. The two-phase shift modulation method of the three-level parallel inverter is characterized by comprising the following steps of: obtaining the area of each phase of the divided modulated wave according to the three-phase modulated wave, and calculating the carrier correction angle of each phase through the area of each phase of the modulated wave; According to a circulation suppression rule, increasing a circulation phase shift angle on the basis of a carrier correction angle and a carrier initial angle to obtain a total phase shift angle; Respectively obtaining a first phase shift comparison value and a second phase shift comparison value corresponding to an upper carrier and a lower carrier according to the total phase shift angle, obtaining each phase voltage of the upper carrier according to the first phase shift comparison value and the second phase shift comparison value of the upper carrier, and obtaining each phase voltage of the lower carrier according to the first phase shift comparison value and the second phase shift comparison value of the lower carrier; generating a switching sequence of each power switching tube according to each phase voltage of the upper carrier wave and each phase voltage of the lower carrier wave, and controlling the three-level parallel inverter; The amplitude direction axes of the upper carrier wave and the lower carrier wave are respectively divided into two areas by taking 1/2 and-1/2 as boundaries, the upper area is an s 1 area, the lower area is an s 2 area, and the initial angles theta p1_1 , 180 of the sinusoidal carrier wave C r1 are in an s 1 area and an s 2 area The initial angle θ p1_2 of the phase-shifted carrier C r2 is pi rad; Sinusoidal carriers C r1 and 180 The correction angle of the phase-shifted carrier C r2 is the same in each region, in the s 1 region, the sinusoidal carriers C r1 and 180 The correction angle of phase-shifted carrier C r2 is 0 rad, in region s 2 , sinusoidal carriers C r1 and 180 The correction angle of the phase-shift carrier C r2 is pi/2 rad, and the three-phase carrier lags pi/2 rad in the region s 2 ; The method comprises the steps of obtaining a comprehensive five-level switching sequence corresponding to each region after overload wave phase shift, synthesizing a reference vector by using the latest three voltage vectors, wherein the circulation phase shift angle of only the modulation wave with the absolute value closest to 1/2 in the two-phase or three-phase modulation wave in the same region is pi rad, the circulation phase shift angles of other phases are 0 rad, and carrier matching phase shift ensures that the average circulation of two continuous periods is zero.
2. The two-phase shift modulation method of three-level parallel inverter according to claim 1, wherein, The total phase shift angle is the sum of the carrier correction angle, the circular phase shift angle and the carrier initial angle.
3. The two-phase shift modulation method of three-level parallel inverter according to claim 1, wherein, The first phase shift comparison value m x1 and the second phase shift comparison value m x2 of the upper carrier are: ; The first phase shift comparison value m x1 and the second phase shift comparison value m x2 of the subcarrier are: ; Wherein, the , Is the total phase shift angle.
4. The two-phase shift modulation method of three-level parallel inverter according to claim 3, The phase voltage v xi of the upper carrier is: ; The phase voltage v xi of the subcarrier is: ; Wherein, the Is a direct current side voltage.
5. A three-level parallel inverter two-phase shift modulation system, characterized by using the three-level parallel inverter two-phase shift modulation method according to any one of claims 1 to 4, comprising: A carrier correction angle calculation unit configured to calculate carrier correction angles of the respective phases from areas where the divided respective phase modulated waves are located, based on the three-phase modulated waves; the total phase shift angle calculation unit is configured to increase the loop phase shift angle on the basis of the carrier correction angle and the carrier initial angle according to the corresponding rule of loop suppression to obtain the total phase shift angle; The phase voltage calculation unit is configured to obtain a first phase shift comparison value and a second phase shift comparison value corresponding to the upper carrier wave and the lower carrier wave respectively according to the total phase shift angle, obtain each phase voltage of the upper carrier wave according to the first phase shift comparison value and the second phase shift comparison value of the upper carrier wave, and obtain each phase voltage of the lower carrier wave according to the first phase shift comparison value and the second phase shift comparison value of the lower carrier wave; and the double phase shift modulation unit is configured to generate a switching sequence of each power switching tube according to each phase voltage of the upper carrier wave and each phase voltage of the lower carrier wave and control the three-level parallel inverter.
6. A computer device comprises a processor and a computer-readable storage medium; A processor adapted to execute a computer program; A computer readable storage medium having a computer program stored therein, which when executed by the processor, implements the three-level parallel inverter two-phase shift modulation method according to any one of claims 1 to 4.
7. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program adapted to be loaded by a processor and to perform the three-level parallel inverter bi-phase shift modulation method according to any one of claims 1 to 4.
8. A computer program product, characterized in that the computer program product comprises a computer program which, when executed by a processor, implements the three-level parallel inverter bi-phase shift modulation method according to any one of claims 1 to 4.

Description

Dual-phase shift modulation method and system for three-level parallel inverter Technical Field The invention relates to the technical field of parallel three-level inverter vector modulation, in particular to a three-level parallel inverter biphase shift modulation method, a three-level parallel inverter biphase shift modulation system, computer equipment, a computer readable storage medium and a computer program product. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. In recent years, with the rapid development of high-power ac power transmission technology, neutral-Point-Clamped (NPC) three-level inverters have been widely used. Compared with the topology of the traditional three-phase two-level inverter, the NPC three-level inverter has the advantages of low voltage stress of power devices, good quality of output waveforms and the like. In high power and rated current applications, the use of a single inverter is often not satisfactory due to the capacity limitations of the semiconductor devices, and parallel inverters are an alternative topology to achieve higher rated power than a single three-level inverter. The flexibility of the parallel inverter voltage capability can improve the efficiency of the system under a wide range of application conditions. However, the problems of the parallel inverter are concentrated on the suppression of zero sequence circulation, the synchronization of the carrier waves of the parallel inverter, the reduction of switching loss, the reduction of Common Mode Voltage (CMV), the improvement of output current ripple and the like, and in order to improve the total output current quality of the parallel inverter, a segmented dual carrier phase shift (DPS-PWM) based on an interleaving scheme is proposed, however, the carrier phase difference of the interleaving scheme can generate circulation. In addition, harmonic components of the circulating current increase thermal stress of a direct current link capacitor and a power semiconductor, limit rated power is caused, and carrier wave difference among inverters can cause an asynchronous switching sequence to generate high-frequency circulating current. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a three-level parallel inverter double-phase shift modulation method and system, which utilize improved double-carrier phase shift pulse width modulation (MDPS-PWM) to reduce the circulating current of a parallel three-level inverter, and realize the suppression of the circulating current of a parallel three-level inverter system and the improvement of output current ripple. In order to achieve the above purpose, the present invention adopts the following technical scheme: in a first aspect, the present invention provides a method for bi-phase shift modulation of a three-level parallel inverter. A dual-phase shift modulation method of a three-level parallel inverter comprises the following steps: obtaining the area of each phase of the divided modulated wave according to the three-phase modulated wave, and calculating the carrier correction angle of each phase through the area of each phase of the modulated wave; according to the corresponding rule of loop current suppression, increasing a loop current phase shift angle on the basis of a carrier correction angle and a carrier initial angle to obtain a total phase shift angle; Respectively obtaining a first phase shift comparison value and a second phase shift comparison value corresponding to an upper carrier and a lower carrier according to the total phase shift angle, obtaining each phase voltage of the upper carrier according to the first phase shift comparison value and the second phase shift comparison value of the upper carrier, and obtaining each phase voltage of the lower carrier according to the first phase shift comparison value and the second phase shift comparison value of the lower carrier; and generating a switching sequence of each power switching tube according to each phase voltage of the upper carrier wave and each phase voltage of the lower carrier wave, and controlling the three-level parallel inverter. The circulation phase shift angle theta cc of the parallel three-level inverter based on the phase shift angle theta 0 is set according to the following rule: F x (x=a, b, c) represents the distance from the absolute value of the modulated wave to 1/2, m a、mb and m c are modulated waves, and s 1 and s 2 are the areas where the divided modulated waves of each phase are located, respectively. As a further limitation of the first aspect of the present invention, the amplitude direction axes of the upper carrier and the lower carrier are divided into two regions with 1/2 and-1/2 as boundaries, the upper region is region s 1, the lower region is region s 2, and the initial angles θ p1_1, 180 of the sinusoidal car