Regenerative braking scheme for conventional vehicle using ultracapacitor

Two new brake energy recovery schemes employing ultracapacitor (UCAP) and a unidirectional power converter are proposed in this paper for recovery of brake energy in the conventional gasoline vehicle. Control algorithms are proposed for the same to direct brake energy (during braking operation) in to UCAP and subsequently from the UCAP to the vehicle loads and battery. The use of stored energy in UCAP relives the alternator torque on the engine, resulting in reduced fuel consumption thereby facilitates improvement in the fuel economy in the vehicle. Both the proposed schemes can be retrofitted as simple add-ons to the existing conventional vehicle thus obviating the need of any modifications to it. The proposed schemes are simulated first using MATLAB and experimentally verified. New European drive cycle (NEDC) is used in this work in order to understand the fuel economy benefits. It is found that the rear axle alternator mounted scheme yields almost thrice times fuel economy benefits compared to the engine mounted alternator scheme.