Unlock instant, AI-driven research and patent intelligence for your innovation.

Nearest half-level approximation PWM hybrid modulation method suitable for medium-voltage three-phase MMC

Active Publication Date: 2020-10-09
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
View PDF10 Cites 3 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the CPS-PWM strategy, the carrier signals of each sub-module are independent of each other, and are widely used in medium-voltage MMCs. However, CPS-PWM requires additional voltage equalization control, which increases the complexity of the control and has high switching losses.
The above modulation methods all use a single modulation method to improve the output voltage quality of the AC side, without combining the advantages of the two modulation methods

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Nearest half-level approximation PWM hybrid modulation method suitable for medium-voltage three-phase MMC
  • Nearest half-level approximation PWM hybrid modulation method suitable for medium-voltage three-phase MMC
  • Nearest half-level approximation PWM hybrid modulation method suitable for medium-voltage three-phase MMC

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0022] The latest half-level approximation PWM hybrid modulation method suitable for medium-voltage three-phase MMC according to the present invention will be described in detail below in conjunction with the accompanying drawings.

[0023] figure 1 It is a typical three-phase MMC topology structure diagram applicable to the present invention. When the medium-voltage MMC adopts the NHL-PWM modulation mode, taking the A phase as an example, the analysis of the operation mode of the upper and lower bridge arms is as follows:

[0024] Such as figure 1 As shown, each bridge arm is composed of N sub-modules and bridge arm inductance L in series, and the voltage of the DC bus is +U dc / 2 and -U dc / 2, figure 1 In p, n and o are the positive and negative poles of the DC bus and the imaginary neutral point respectively, and the capacitor voltage is U c , when the voltage modulation coefficient is M, the upper and lower bridge arm reference voltage U pa_ref and U na_ref As shown ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention discloses a nearest half-level PWM hybrid modulation method (NHL-PWM) suitable for a medium-voltage MMC. When the medium-voltage MMC adopts an NHL-PWM modulation strategy, an upper bridge arm and a lower bridge arm adopt different modes to approach reference waves, the waveform quality of the output voltage of the alternating-current side is improved, and the NHL-PWM follows a capacitor voltage equalization strategy of an NLM modulation mode, so that the control strategy is simplified, and the waveform quality of the output voltage of the alternating-current side is improved.

Description

[0001] Patent field [0002] The invention relates to a modulation strategy capable of improving the output waveform quality of a medium-voltage MMC, in particular to a PWM hybrid modulation method suitable for a medium-voltage MMC, and belongs to the technical field of power electronics. Background technique [0003] The DC distribution network based on the modular multilevel converter (MMC) will play an important role in the future smart distribution network due to its advantages of small transmission loss, modular design, flexible control and easy acceptance of new energy. . The voltage level of the medium-voltage MMC-based DC distribution network is generally low, and the number of MMC sub-modules is generally small. If the step wave approximation modulation strategy is used in the flexible high-voltage DC transmission, it will cause high harmonic content in the output waveform and large phase-to-phase differences. Large circulating current and other issues. [0004] The...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/501H02M7/5387H02M7/5395H02M1/12
CPCH02M7/483H02M7/501H02M7/53871H02M7/5395H02M1/12H02M7/4835
Inventor 王琛许同王毅陶建业
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)