회생 제동 에너지 회수율 최대화 및 차량 안전성을 보장을 위한 하이브리드 연료 전지 자동차의 회생 제동 협조 제어

Abstract

One of the most important control problems to improve fuel economy in fuel cell hybrid electric vehicle is cooperative regenerative braking control strategy because the electric motor can convert the kinetic or potential energy into electric energy that can be stored in super-capacitor and reused. In this study, an electric motor for regenerative braking is directly connected to the front drive axle only because front-wheel drive vehicle is common for passenger vehicle. Vehicle stability can be lost in case regenerative braking torque is applied only to front wheels for maximum braking energy recovery, i.e., FCHEV might get into an unstable motion called lock-up and understeer. Therefore, we propose systematic controller guaranteeing the vehicle stability while guaranteeing maximum regenerative braking energy recovery. Upper controller generates the desired yaw moment calculated by using LQR method for following the desired the yaw rate and side slip angle. And lower controller applies optimal regenerative braking torque and mechanical braking torque independently within equality constraints (the required total longitudinal force and yaw moment) and inequality constraints (friction circle) for optimal regenerative braking energy recovery. Carsim™ computer simulation is used to verify the effectiveness of the proposed controller.