Fuel cell air system, fuel cell system, vehicle and control method

The invention provides a fuel cell air system, a fuel cell system, a vehicle and a control method.The system is applied to the vehicle and comprises an air compressor, a turbine generator, a first bypass loop arranged between the air compressor and the turbine generator and a second bypass loop arranged in the turbine generator, when the fuel cell system is in a low-power power generation working condition, the first bypass loop is controlled to be opened, and part of compressed air is discharged from the first bypass loop and the turbine runner; and when the fuel cell system is in a low-temperature cold start working condition, the first bypass loop and/or the second bypass loop are/is controlled to be opened, and compressed air and/or waste gas of the fuel cell are/is used for heating a rotating part of the turbine generator. According to the system, the air compressor and the turbine generator can be arranged in a distributed mode, the redundancy is high, the bypass loop is opened during low-temperature co