System for diagnosing switching element selectively connecting Y-capacitors to ground

A system for diagnosing switching element selectively connecting Y-capacitors to ground, comprising:

• a first Y-capacitor group including a first capacitor and a second capacitor connected in series between a positive terminal and a negative terminal of a direct current (DC) link;
• a second Y-capacitor group including a third capacitor and a fourth capacitor connected in series between the positive terminal and negative terminal of the DC link;
• a Y-capacitor disconnect switch having a first terminal connected to a connection node of the first capacitor and second capacitor and a second terminal connected to a connection node of the third capacitor and fourth capacitor, wherein one of the first terminal and the second terminal is connected to the ground;
• a power conversion circuit connected to the DC link, the power conversion circuit including a switching device and determining a DC voltage of the DC link by on/off of the switching device;
• and
• a controller configured to adjust a state of the switching device in the power conversion circuit to form different voltages at both the terminals of the Y-capacitor disconnect switch, and then control a disconnection operation state of the Y-capacitor disconnect switch and diagnose whether a fault has occurred in the Y-capacitor disconnect switch, based on the voltages at both the terminals of the Y-capacitor disconnect switch.