A study on generating braking force by permanent magnet synchronous motors when regenerative braking is disabled for fuel cell vehicles

The main battery capacity of fuel cell vehicles (FCVs) is about one-tenth that of pure electric vehicles because the primary purpose of the FCV main battery is compensation of fuel cell output power response. The smaller battery capacity may cause regenerative braking to become disabled halfway through a continuous downhill (such as Hakone). Therefore, this paper proposes driving-points of the 1 st or 4 th quadrant on the d-q coordinate system. Unlike conventional high efficiency control, the driving-points are aimed at increasing traction motor losses as may be necessary in order to avoid hard use of the friction brake. This method realizes sufficient braking force without charging the FCV main battery by converting the braking energy into the traction motor and its inverter losses. © 2019 The Institute of Electrical Engineers of Japan.