Method and a Device for Compensating a Faulty Switch in a Multi-Level Flying Capacitor Converter

Patent metadata

Field	Value
Publication number	US-2023083355-A1
Application number	US-202217943693-A
Country	US
Kind code	A1
Filing date	Sep 13, 2022
Priority date	Sep 14, 2021
Publication date	Mar 16, 2023
Grant date	—

Abstract

A system and method for compensating a faulty switch in a multi-level flying capacitor converter includes a converter capacitor arranged in parallel to an input, a first and second converter switches arranged respectively between first and second ends of the converter capacitor, first and second bypass switches respectively arranged in parallel to the first and second converter switches, wherein operation includes detecting a faulty converter level that includes at least one of the first and second converter switches, discharging all capacitors arranged in parallel to the input of the multi-level converter, wherein all capacitors comprise the converter capacitors and an input capacitor; closing the first and second bypass switches of the faulty converter level; adapting a modulation of the converter switches of the other converter levels; and restarting the multi-level converter.

First claim

What is claimed is:

1 . A method for compensating a faulty switch in a multi-level flying capacitor converter, wherein each converter level of the multi-level flying capacitor converter comprises:
a converter capacitor arranged in parallel to an input of the multi-level converter; a first converter switch and a second converter switch, the first converter switch being arranged between a first end of the converter capacitor, and the second converter switch being arranged between a second end of the converter capacitor; a first bypass switch arranged in parallel to the first converter switch; and a second bypass switch arranged in parallel to second converter switch; wherein the method comprises: detecting a faulty converter level, wherein the faulty converter level comprises at least one of the first converter switch and the second converter switch being faulty; discharging all capacitors arranged in parallel to the input of the multi-level converter, wherein all capacitors comprise the converter capacitors and an input capacitor; closing the first bypass switch and the second bypass switch of a level containing the first or second converter switch that is faulty; adapting a modulation of the converter switches of other converter levels; and restarting the multi-level converter.

2 . The method of claim 1 , further comprising continuing to run the multi-level converter ( 100 ).

3 . The method of claim 1 , further comprising disconnecting the multi-level converter from an input voltage before discharging all capacitors.

4 . The method of claim 1 , further comprising conducting an initial check of the multi-level converter before continuing to run the multi-level converter.

5 . The method of claim 1 , wherein discharging all capacitors comprises discharging the capacitors at least partially.

6 . The method of claim 1 , wherein detecting a faulty converter level comprises identifying the first converter switch and/or the second converter switch having a short-circuit error or an open-circuit error.

7 . The method of claim 6 , wherein identifying the converter switch having an open-circuit error comprises measuring a maximum voltage at one of the converter capacitors, and applying a sequence of switching vectors to all switches of the multi-level flying capacitor converter.

8 . The method of claim 6 , wherein identifying the converter switch having a short-circuit error comprises measuring a zero difference voltage between two of the converter capacitors.

9 . A multi-level flying capacitor converter for DC/AC converting having a plurality of converter levels, wherein each converter level of the plurality of converter levels comprises:
a converter capacitor arranged in parallel to an input of the multi-level converter; a first converter switch and a second converter switch that are arranged between a first end and a second end of the converter capacitor respectively; a first bypass switch and a second bypass switch that are arranged in parallel to the respective first converter switch and to the respective second converter switch; and a control unit configured for:
detecting a faulty converter level, wherein the faulty converter level comprises at least one of the first converter switch and the second converter switch being faulty;
discharging all capacitors arranged in parallel to the input of the multi-level converter, wherein all capacitors comprise the converter capacitors and an input capacitor;
closing the first bypass switch and the second bypass switch of a level containing the first or second converter switch that is faulty;
adapting a modulation of the converter switches of other converter levels; and
restarting the multi-level converter.

10 . The multi-level converter of claim 9 , wherein the multi-level converter comprises between 2 and 10 converter levels.

11 . The multi-level converter of claim 9 , wherein the multi-level converter comprises between 3 and 6 converter levels.

12 . The multi-level converter of claim 9 , further comprising at least one of:
an input capacitor; and an output low-pass.

Assignees

• Abb Schweiz Ag

Inventors

• Bishnoi Hemant
• Pettersson Sami
• Schweizer Mario
• Christen Daniel
• Riedel Gernot

Classifications

• Y02E10/56

  Power conversion systems, e.g. maximum power point trackers · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M1/325

  with means for allowing continuous operation despite a fault, i.e. fault tolerant converters · CPC title

• H02M1/322 Primary

  Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock · CPC title