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Controlling method of compositely controlled cascaded multilevel inverter and multilevel inverter

A cascaded multi-level, hybrid control technology, applied in irreversible DC power input conversion to AC power output, photovoltaic power generation and other directions, can solve problems such as large switching loss, high operating frequency of switching devices, and complex system.

Active Publication Date: 2011-06-01
EAST GRP CO LTD
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

The advantage of the ladder wave algorithm is that the switching device works at the frequency of the modulation wave (power frequency), the switching frequency is low, and the efficiency is high. Its disadvantage is that the output power needs to be adjusted by adjusting the DC voltage, and the system is relatively complicated.
The advantage of the instantaneous value feedback algorithm is that the output power can be adjusted through the pulse width or the phase shift between the bridge arms, the system structure is simple, and the output waveform quality is good. Big

Method used

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  • Controlling method of compositely controlled cascaded multilevel inverter and multilevel inverter
  • Controlling method of compositely controlled cascaded multilevel inverter and multilevel inverter
  • Controlling method of compositely controlled cascaded multilevel inverter and multilevel inverter

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Experimental program
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Embodiment 1

[0125] see figure 1 , a control method for cascaded multi-level inverters mixed with step wave and instantaneous value feedback, including:

[0126] Step 101, using the ladder wave algorithm to control N groups of photovoltaic cells, including:

[0127] Step 1011. Obtain the output voltages of N groups of photovoltaic cells, and obtain the 1st, 2nd, ..., i, ..., N output voltages;

[0128] Step 1012. Calculate the conduction angle θ of the 1st, 2nd, ..., i, ..., N output voltages 1 ', θ 2 ', ..., θ i ', ..., θ N ':

[0129]

[0130] The conduction angle θ calculated by the above formula 1 ', θ 2 ', ..., θ i ', ..., θ N ' Round up to an integer to get the conduction angle θ 1 , θ 2 ,...,θ i ,...,θ N :

[0131] θ 1 = ceil ( θ 1 ′ ...

Embodiment 2

[0262] A ladder wave cascaded multilevel inverter, comprising:

[0263] The ladder wave algorithm control unit is used to control N groups of photovoltaic cells using the ladder wave algorithm. The control process includes:

[0264] Step A1. Obtain the output voltages of N groups of photovoltaic cells, and obtain the 1st, 2nd, ..., i, ..., N output voltages;

[0265] Step A2. Calculate the conduction angle θ of the 1st, 2nd, ..., i, ..., N output voltages 1 ', θ 2 ', ..., θ i ', ..., θ N ':

[0266]

[0267] The conduction angle θ calculated by the above formula 1 ', θ 2 ', ..., θ i ', ..., θ N ' Round up to an integer to get the conduction angle θ 1 , θ 2 ,...,θ i ,...,θ N :

[0268] θ 1 = ceil ( θ 1 ′ ) ...

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Abstract

The invention discloses a control method of a hybrid-control cascaded multilevel inverter and a multilevel inverter. The controlling method comprises the following steps: obtaining output voltages of N groups of photovoltaic cells to get 1st, 2nd,..., ith,..., Nth output voltages; counting conduction angles theta1', theta2',..., thetai',...,thetaN' of the 1st, 2nd,..., ith,..., Nth output voltages; ceiling to obtain theta1, theta2, theta(i),..., theta(N); controlling the conductions of the 1st, 2nd,..., ith,..., Nth output voltages respectively by utilizing the conduction angles theta1, theta2, thetai,..., thetaN; obtaining step wave output voltages by utilizing a step wave algorithm; obtaining the output voltages of m groups of photovoltaic cells; utilizing an instantaneous value feedback algorithm to get instantaneous value feedback output voltages; and serially overlapping the step wave output voltages with the instantaneous value feedback output voltages to form a total output voltage, thus implementing the change from the DC (direct current) multilevel input into the AC (alternating current) level output. By using the scheme provided by the invention, the work frequency can be decreased, the conversion efficiency of the inverter is improved, the electromagnetic interference is reduced and the system structure is simplified.

Description

technical field [0001] The invention relates to the technical field of cascaded multilevel inverters, in particular to a control method for hybrid control of cascaded multilevel inverters and the multilevel inverter. Background technique [0002] At present, there are mainly three topological structures in medium and high voltage high-power inverter devices: diode-clamped multilevel inverter (NPC), flying capacitor multilevel inverter (FC), cascaded Multilevel Inverter (Cascaded). Among them, the cascaded multi-level inverter has the following advantages, such as low power switch tube stress, small output voltage harmonic content, high harmonic order, etc., and the least number of devices is required to achieve the same output level, and there is no DC side capacitance. Voltage equalization and other issues, high reliability, is the preferred topology for solar photovoltaic power generation systems, fuel cells and other outputs or grid-connected inverters. [0003] There a...

Claims

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Application Information

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IPC IPC(8): H02M7/48
CPCY02E10/56
Inventor 徐海波朱忠尼宋庆国陈元娣
Owner EAST GRP CO LTD
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