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Voltage equalization method of diode-clamped multilevel converter based on carrier modulation

A technology of diode clamping and carrier modulation, applied in the direction of output power conversion device, conversion of AC power input to DC power output, electrical components, etc., can solve problems such as not given, poor algorithm flexibility, etc., and achieve simple and universal algorithm Strong, easy-to-achieve effects

Active Publication Date: 2019-06-28
INST OF ELECTRICAL ENG CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method does not give the mathematical expression of the required injected zero-sequence voltage, and it is proposed for back-to-back applications, and the algorithm flexibility is poor

Method used

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  • Voltage equalization method of diode-clamped multilevel converter based on carrier modulation
  • Voltage equalization method of diode-clamped multilevel converter based on carrier modulation
  • Voltage equalization method of diode-clamped multilevel converter based on carrier modulation

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Embodiment 1

[0049] Embodiment 1 is the first method for calculating zero-sequence voltage in the present invention, which is based on predictive control. In each carrier cycle, by predicting and comparing the deviation value of the DC capacitor voltage at the end state of the carrier cycle after different zero-sequence voltage injections, the DC capacitor voltage deviation of the 3-phase five-level diode-clamped multilevel converter is selected to be the smallest The zero-sequence voltage to control the 3-phase five-level diode-clamped multilevel converter.

[0050] Figure 4 Shown is a flow chart of a calculation method for determining the injected zero-sequence voltage of a 3-phase five-level diode-clamped multilevel converter based on predictive control in a certain control period, and the specific steps are as follows:

[0051] (1) Sampling the voltage u of each DC capacitor Ci_sample , three-phase modulation wave u x and load current i x , i={1,2,3,4}, x={1,2,3}, reset zero seque...

Embodiment 2

[0072] Embodiment 2 is the second method of calculating the zero-sequence voltage based on the proportional-integral controller of the present invention. The method samples the voltage of each floating node of the DC capacitor bank, and uses a proportional-integral controller to generate the zero-sequence voltage that needs to be injected according to the voltage deviation value of the floating node with the largest voltage deviation and the polarity of the instantaneous active power absorbed by the load.

[0073] Figure 5 Shown is a certain control period, based on the proportional integral controller (PI) 3-phase five-level diode-clamped multilevel converter principle block diagram for calculating the zero-sequence voltage, specifically:

[0074] (1) Sampling three-phase modulation wave u x , load current i x and each floating node N of the DC capacitor bank 2 , N 3 and N 4 voltage u N2 , u N3 and u N4 , x={1,2,3};

[0075] (2) Calculate the instantaneous active po...

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Abstract

A voltage equalization method for a diode-clamped multilevel converter based on carrier modulation, through injecting a zero-sequence voltage into a carrier-modulated modulation wave, realizes the voltage equalization control of multiple series-connected DC capacitors of a DC capacitor bank. The mathematical expression of the injected zero-sequence voltage is u z =k(1‑u max )+(1‑k)(‑1‑u min ), where u max and u min are the maximum and minimum values ​​of all phase modulation waves respectively, and k is the zero-sequence factor, satisfying 0≤k≤1. The present invention adopts two methods to calculate the zero-sequence voltage. The first method determines the zero-sequence voltage based on predictive control, which can simultaneously suppress the switching frequency of the bridge arm; the second method determines the zero-sequence voltage based on a closed-loop proportional-integral controller.

Description

technical field [0001] The invention relates to a voltage equalization method of a diode-clamped multilevel converter based on carrier modulation. Background technique [0002] The DC capacitor bank of the diode-clamped multilevel converter is composed of multiple DC capacitors connected in series, and the connection point between the DC capacitors is a floating node. Each floating node is connected to the bridge arm of the diode-clamped multilevel converter through a clamping diode network. The bridge arm of a diode-clamped multilevel converter consists of a series-connected power switching device and a clamping diode network. Through the control device of the diode-clamped multilevel converter, changing the switching state of the power switching device of the bridge arm can obtain multiple level values ​​provided by the DC capacitor bank at the output end of the bridge arm. [0003] However, due to the asymmetry of the DC capacitors inside and outside the DC capacitor ba...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483H02M1/32
CPCH02M1/32H02M7/483H02M7/4835
Inventor 葛琼璇崔冬冬
Owner INST OF ELECTRICAL ENG CHINESE ACAD OF SCI