Regenerative braking control of im with battery/ultracapacitor hybrid ESS in electric vehicles

For energy saving in Electric Vehicles (EVs), high kinetic energy could be exploited by designing a regenerative braking control of traction machine and usage of hybrid energy storage system (HESS). This paper presents a regenerative braking strategy of an Induction Motor (IM) drive. This strategy is composed of two stages. First, field-oriented speed control is developed at running and braking modes. Second, power distribution technique is proposed to share the power between the battery and ultracapacitor (UC) in the HESS via a DC-DC converter with buck-boost modes. In motoring operation i.e. discharge mode, a current control technique is used to get the optimal distribution factor for achieving maximum discharge efficiency. In regenerative operation i.e. charging mode, DC-link voltage control mode is adopted. First, the amount of the regenerated power at braking is measured and verified by experimental testes at which the IM is braked using a slip control technique. Then, the IM is excited by the HESS and the discharging/charging of the battery and UC at running/breaking is validated by simulations. Experimental and simulation results ensure the proposed strategy for exploiting the kinetic energy during braking of the EV.