Switch short-circuited diagnosis method

A switch short-circuited diagnosis method, configured for detecting a short-circuited state of a first bidirectional switch module;

• the first bidirectional switch module comprising a first switch branch, a second switch branch, and a third switch branch;
• the first switch branch being coupled to a first phase wire of a three-phase power source, the second switch branch being coupled to a second phase wire of the three-phase power source, and the third switch branch being coupled to a third phase wire of the three-phase power source, the method comprising steps of:
• determining an initial voltage interval of multiple voltage intervals according to voltage relationships between a voltage of the first phase wire, a voltage of the second phase wire, and a voltage of the third phase wire;
• and
• respectively performing the switch short-circuited diagnosis of the first bidirectional switch module from the initial voltage interval to the three consecutive voltage intervals, and comprising steps of:
• turning on the first switch branch, the second switch branch, or the third switch branch of the first bidirectional switch module according to the voltage relationships between the voltage of the first phase wire, the voltage of the second phase wire, and the voltage of the third phase wire;
• determining whether an overcurrent occurs to diagnose whether the first switch branch, the second switch branch, or the third switch branch of the first bidirectional switch module is in the short-circuited state;
• and
• performing the switch short-circuited diagnosis for the next voltage interval.