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Impact of Vehicle Electrification on Brake Design
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on November 21, 2019 by SAE International in United States
Event: NuGen Summit
Electric vehicles have come full circle from being primary vehicle type in 19th century (much before IC powered vehicles) to 21st century where major stake holders in mobility have announced plans towards vehicle electrification. Apart from battery & powertrain system, braking system is area which will undergo major changes because of vehicle electrification. But Why? Major keywords are regenerative braking, increased vehicle weight, no or insufficient vacuum from engine and silent powertrains. This paper tries to outline potential impact on hydraulic brake system & its component design for M1 and N1 category of four wheelers with advent of vehicle electrification. Needless to say extent of change will vary depending upon extent of electrification and extent of recuperation during regenerative braking. Extent of electrification depends upon whether vehicle is range extender type hybrid vehicle, plug in hybrid vehicle, battery electric vehicle, fuel cell vehicle etc. Extent of electrification defines in turn extent of recuperation possible, extent of increase in vehicle weight, availability of vacuum and NVH of powertrains. Extent of recuperation is constrained by motor generator capacity, vehicle stability and system capability to seamlessly coordinate between hydraulic braking and regenerative braking. Extent of recuperation defines braking force distribution between hydraulic braking and regenerative braking, requirement of braking torque coordination strategies without changing pedal feel much from conventional vehicles. On the other hand, higher recuperation level allows innovative braking strategies like one pedal driving. This paper summarizes impact of above factors on various design parameters like braking control system, control strategies, brake system size, component structure, brake pad life, brake pad ageing due to longer life, anti-corrosion requirements, brake noise, judder and other NVH performance. These changes along with others due to emerging trends like autonomous driving and requirement of green technologies will require changes in design specifications and testing procedures in coming time.