Three-level brake chopper and method for controlling three-level brake chopper

A three-level brake chopper comprising:

• a positive direct current pole, a negative direct current pole, and a neutral direct current pole;
• a first controllable semiconductor switch connected between the positive direct current pole and a first connection point;
• a second controllable semiconductor switch connected between the first connection point and the neutral direct current pole;
• a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point;
• a fourth controllable semiconductor switch connected between the second connection point and the negative direct current pole;
• resistance means connected between the first connection point and the second connection point;
• and
• a control arrangement configured to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the resistance means.

A three-level converter device, comprising a three-level brake chopper comprising:

• a positive direct current pole, a negative direct current pole, and a neutral direct current pole;
• a first controllable semiconductor switch connected between the positive direct current pole and a first connection point;
• a second controllable semiconductor switch connected between the first connection point and the neutral direct current pole;
• a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point;
• a fourth controllable semiconductor switch connected between the second connection point and the negative direct current pole;
• at least one resistor connected between the first connection point and the second connection point;
• and
• a control arrangement configured to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the at least one resistor.

A three-level brake chopper apparatus comprising:

• a positive direct current pole, a negative direct current pole, and a neutral direct current pole;
• a first controllable semiconductor switch connected between the positive direct current pole and a first connection point;
• a second controllable semiconductor switch connected between the first connection point and the neutral direct current pole;
• a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point;
• a fourth controllable semiconductor switch connected between the second connection point and the negative direct current pole;
• at least one brake resistor connected between the first connection point and the second connection point;
• and
• a control arrangement comprising a processor, and a memory storing instructions that, when executed by the processor, cause the control arrangement to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the at least one brake resistor.