Method for controlling multilevel converter

Patent metadata

Field	Value
Publication number	US-9455618-B2
Application number	US-201414284906-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	May 28, 2013
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

The present disclosure provides a method for controlling a multilevel converter, the method including, detecting modulation state values and current directions of sub-modules, and designating, by one sub-module, an average number of switching for each period of an output waveform, wherein the step of designating the average number of switching includes, grouping the sub-modules according to being in ON state or in OFF state, comparing the number of sub-modules in previous ON state and the number of sub-modules in OFF state to obtain a difference therebetween, and changing a state as much as the difference, comparing a sub-module of ON state in charged state and in discharged state with a sub-module of OFF state, and changing the compared states of sub-modules of ON state and OFF state.

First claim

What is claimed is:

1. A method for controlling a multilevel converter, the method comprising:
detecting states (ON/OFF) and directions of current of sub-modules; and
controlling output voltage of the multilevel converter by turning-on or turning-off the sub-modules,
wherein the controlling the output voltage of the multilevel converter includes:
grouping the sub-modules into a first group including sub-modules that are in an ON state and a second group including sub-modules that are in an OFF state, sorting the sub-modules according to their capacitor voltages; and
turning-on or turning-off the sub-modules by determining a difference between a number of sub-modules to be turned-on and a number of sub-modules that was previously in the ON state.

2. The method of claim 1 , further comprising:
forcibly changing a state of both a sub-module in the ON state and a sub-module in the OFF state if a voltage of the sub-module in the ON state is greater than a voltage of the sub-module in the OFF state during a charging period, or if a voltage of the sub-module in the ON state is less than a voltage of the sub-module in the OFF state during a discharging period.

3. The method of claim 2 , further comprising:
forcibly changing a state of a plurality of sub-modules in the ON state and a plurality of sub-modules in the OFF state.

4. The method of claim 1 , wherein the turning-on or turning-off the sub-modules is based on the detected directions of current and includes:
turning-on a sub-module having a lowest voltage during the charging period; and
turning-on a sub-module having a highest voltage during the discharging period.

5. The method of claim 1 , wherein the turning-on or turning-off the sub-modules is based on the detected directions of current and includes:
turning-off a sub-module having a highest voltage during the charging period; and
turning-off a sub-module having a lowest voltage during the discharging period.

6. The method of claim 1 , wherein the sub-modules are sorted according to a voltage of each of the sub-modules for each of the first and second groups.

Assignees

• Lsis Co Ltd
• Industry-Academic Cooperation Foundation Yonsei Univ

Inventors

• Son Gum Tae
• Hur Kyeon
• Park Jung Wook
• Lee Hee Jin
• Nam Tae Sik
• Chung Yong Ho
• Baek Seung Taek
• Lee Wook Hwa

Classifications

• H02M2001/0003

  Electricity · mapped topic

• H02M2007/4835

  Electricity · mapped topic

• H02M7/49

  Combination of the output voltage waveforms of a plurality of converters · CPC title

• H02M1/08 Primary

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02M7/4835

  comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage · CPC title