Turbocompressors 1 comprise a turbine 10, a compressor 30, a rotatable shaft 20 connecting the turbine 10 and compressor 30 at opposite ends of the shaft 20, and an electric motor 50 coupled to the compressor 30. The turbine 10 comprises an inlet port 14 configured to receive an air feed, and a turbine wheel 12 connected to the shaft 20 and configured to rotate in response to a torque (.tau..sub.M) provided by the air feed. The rotation of the turbine wheel 12 is rotates the rotatable shaft 20 and a compressor wheel 32 of the compressor 30 connected thereto. The compressor 30 comprises an inlet port configured to receive and compress an air feed. The electric motor 50 may deliver a torque (.tau..sub.M) to the compressor wheel 32 in a direction opposite the direction of rotation of the rotatable shaft 20 in order to shut down the turbocompressor 1.