engleski

THEORY AND SIMULATION OF INDUCTION MACHINE BRAKING USING THE HIGH SLIP BRAKING METHOD

Many applications for induction machine variable speed drives (VFDs) require occasional negative torque for braking. This implies that the mechanical energy stored in a rotating mass of the load must be taken away from the load and handled correctly without causing damage to the drive. Usually, the regenerated braking energy is fed back into the grid or safely dissipated as heat using a chopper in the DC link of the drive. If the drive is not equipped with a converter allowing the transfer of energy from the DC link to the grid and there is no chopper present to dissipate the regenerated energy, a possible alternative to achieve braking torque is to dissipate the regenerated energy in the induction machine itself in the form of heat losses. The most well know method for braking using machine losses is the DC injection braking method but with recent developments of the VFD control techniques, other methods of braking are made possible which can achieve higher braking torques per ampere when compared to DC injection braking. In this paper, the method known as high slip braking (HSB) is described. The theory of operation of high slip braking is discussed and a novel control method is proposed. The paper also includes simulation results of braking an 11kW induction machine using the high slip braking with the proposed control method.

Induction motor ; high slip braking ; variable frequency drives.

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