Short-circuit detection device and method used in inverter circuit

A device for detecting a short circuit fault in a multi-level inverter circuit, the inverter circuit comprising a plurality of single phase branches, each of which comprises a plurality of switches, the device comprising:

• a pulse transmitting module for transmitting at least one detection pulse sequence to the plurality of switches of the single phase branch, wherein the at least one detection pulse sequence comprises a number of “0” and “1” pulses and the “0” and “1” pulses are transmitted to the switches respectively, wherein the “0” pulse represent a low level pulse and the “1” pulse represent a high level pulse;
• a loop determining module for determining whether a conducting loop is formed in the single phase branch according to the detection pulse sequence;
• and
• a fault detection module for locating a position of a malfunctioned switch of the single phase branch according to a path of the conducting loop when the conducting loop exists,
• wherein a switch corresponding to the “0” pulse is determined as a short circuit fault, and after the switch corresponding to the “0” pulse is determined as the short circuit fault, a short-circuit protection process is performed to shut down the multi-level inverter circuit.

A three-phase three-level inverter circuit, comprising:

• a capacitor module, comprising a first capacitor and a second capacitor electrically coupled in series via a first node;
• three single-phase branches, each single-phase branch coupling to the capacitor module in parallel, each single phase branch comprising:
• a first diode and a second diode electrically coupled in series between a third node and a fourth node via a second node, wherein the second node is electrically coupled to the first node;
• a first switch and a second switch electrically coupled via the third node;
• and
• a third switch and a fourth switch electrically coupled via the fourth node, wherein the second switch and the third switch are electrically coupled via a fifth node;
• and
• a fault detection module for transmitting a detection pulse sequence comprising a number of “0” and “1” pulses to the first switch, the second switch, the third switch and the fourth switch, wherein the “0” pulse represent a low level pulse and the “1” pulse represent a high level pulses, in the single-phase branch, the fault detection module determining whether a conducting loop exists in the single-phase branch according to the detection pulse sequence, and for locating a position of one or more defective short-circuit switches in the single-phase branch according to a path of the conducting loop when the conducting loop exists in the single phase branch.