Development of an Auxiliary Pressurized Hybrid Brake System for a Parallel Hybrid Electric Commercial Van

Efficient use of oil resources has become the number one priority throughout the world. Vehicles, operating with alternative fuels like solar or hydrogen energy are still in the development phase. In this transition period, automotive companies are trying to produce more efficient road vehicles to reduce the negative impacts of the internal combustion engine. Advances in high-efficiency electrical machines (EM), high-specific energy/power units, lower-cost power electronics and embedded systems have promoted the use of EM solely and/or along with the internal combustion engine (ICE) to develop pollution-free vehicles. Due to the high cost of the energy storage units for a pure electric drive the current trend is towards the practice of hybrid electric vehicle (HEVs). This paper presents the design of a novel brake system, namely Auxiliary Pressurized Hybrid Brake System (APHBS), which enables energy recovery and a safe transition from regenerative brake (RB) to hydraulic brake (HB) with minimum intervene to the existing hydraulic brake line of the second generation Ford Transit hybrid electric van. To be able to develop a commercially feasible system, not only energy recovery but also safety is considered during the development phase. Since the vehicle's existing hydraulic brake module is not altered; system functions as a conventional brake system in case of a failure, panic stopping condition and violation of the limits of EM and/or battery. Under normal operating conditions and when the braking deceleration is less than the predetermined value, the proposed system runs the front and rear electrical machines in the generator mode to recover the kinetic energy of the vehicle resulting in fuel savings. If the desired braking force cannot be generated by regenerative braking, a safe transition is provided from RB to HB through the auxiliary pressurized brake line. This proposed system is simulated in MATLAB^®/Simulink to demonstrate its successful operation. The simulation results have shown that a continuous braking without compromising the brake performance and energy recovery can be maintained by the implementation of the APHBS to the hybrid van.