Variable-section air compressor with energy recovery unit for fuel cell

The invention discloses a variable-section air compressor with an energy recovery unit for a fuel cell. The variable-section air compressor comprises a motor shell, two ends of the motor shell are provided with a press end and a vortex end, the press end is used for compressing air for the fuel cell to use, the vortex end is used for recovering excess energy in waste gas after reaction of the fuel cell to reduce energy waste, a section adjusting mechanism is arranged in the vortex end, an angle adjusting structure is additionally arranged at the vortex end, the flow area of gas can be controlled, the flow area of the gas is reduced in low-speed small flow, the high pressure ratio is kept, a turbine is pushed to rotate more easily, the responsiveness of the air compressor is improved, and energy in waste gas is fully utilized; and the opening degree of a blade can be accurately controlled according to requirements, so that the performance of each working condition is optimal, the energy in the waste gas genera