Main circuit of traction system and control method therefor and rail vehicle

A method for controlling a main circuit of a traction system, comprising:

• under a braking condition,
• controlling a protection module to be turned off, wherein the protection module comprises a first controllable switch and a second controllable switch that are connected in series with opposite polarities, and the first controllable switch and the second controllable switch are integrated into a current conversion module of the main circuit of the traction system;
• controlling the protection module to be turned on and monitoring a first current detected by a first current sensor in a case that a rail vehicle runs on a charged third rail;
• and
• controlling the protection module to be turned off and monitoring whether the rail vehicle runs on a charged third rail in a case that the first current is less than a first preset value.