Energy-consumed braking phase trajectory of induction motor based on Bang-Bang optimal theory

A novel analysis approach to energy-consumed braking phase trajectory (ECBPT) of induction motor based on Bang-Bang optimal theory is presented in this paper. Because the braking torque is a function of the rotor speed, the phase trajectory of conventional direct-current braking method (CDCB) move along the cluster of the optimal switching curves and converge to the origin, so that the time cost of the CDCB is much more than the optimal time cost. From deep derivation of the ECBPT equation, the variable-current braking method (VCB) which will approach the ECBPT to the optimal switching curve well is proposed. The result of simulation and experiment show that the proposed method VCB works much better than CDCB on time cost, instantaneous peak current and energy loss while braking. Due to the quite small energy loss in braking, VCB is especially suitable to induction motors which have higher power, and it also can effectively prevent the motor from over-current, over-heating and other problems when fast braking.