Abstract: Affected by the large voltage fluctuation range of the overhead line in underground coal mines, wire trolley can not often operate efficiently and safely. Applying traction and feedback operation characteristics of bidirectional converters and combining structure and control strategy of bidirectional converters to achieve the use of bidirectional converters and diode rectifiers, which realizes the purpose of a stable DC net pressure and effectively solves the problem of inefficient and unsafe operation of wire trolley. The research results showed that the use of bidirectional converters could quickly feed the excess energy generated by the electric brake of wire trolley back to the high-voltage grid, which could suppress line voltage rise too high and protect the safety of vehicle inverter. The application of bidirectional converters could also compensate for system reactive power and improve power factor, which guaranteed the safe and efficient operation of wire trolley.