Extending the cruising distance of fuel cell electric vehicles by active motor-generator loss control

Small capacity battery of fuel cell electric vehicles (FCEVs) may cause regenerative braking to become disabled halfway through long downhill. To prevent brake lost accident, FCEVs mount a huge discharge resistor which restricts hydrogen space. Then this paper proposes motor-generator loss increase control as a substitute for the resistor. The proposed method realizes sufficient braking force without charging the FCEV battery by converting the braking energy into the motor-generator and its inverter losses. The algebraic analysis of the current vector set-point of the proposed method using motor-generator parameters is clarified. Moreover the principle of the proposed method was verified by small scale experiments using 2-kW machine. By using the proposed method, it is possible to mount additional hydrogen tank instead of the resistor and extend the cruising distance.