Advanced Power Dissipation Strategies for Friction Brake Usage Reduction under high-load conditions in Electric Vehicles

This paper presents a powertrain control strategy for hybrid and battery electric vehicles. The architecture that was used for simulation and testing is an extended-range electric vehicles (EREVs) equipped with dual electric drive motors and a generator-coupled internal combustion engine (ICE) that is not mechanically connected to the wheels, but the same feature may be used for any vehicle that relies on a combination of regenerative and mechanical brakes. During prolonged downhill driving under high-load conditions—such as high battery State of Charge (SOC), full passenger or cargo load, and towing—regenerative braking may be insufficient, increasing reliance on friction brakes and risking overheating. To address this, the proposed feature activates a combination of discrete and continuous energy dissipation mechanisms to absorb excess power and enhance braking performance. Discrete dissipators include the battery thermal conditioning system, ICE cooling system, and induced motor inefficiencies to increase electrical losses, which are estimated by the hybrid control module. The continuous dissipator is the ICE operating in a fuel-cut “Engine Spinning Mode,” providing mechanical drag without triggering emissions faults or catalyst degradation; additional drag can be introduced by engaging the engine’s mechanical fan. A prioritization method enables these dissipators progressively based on power demand. The control architecture integrates an open-loop estimator to calculate required dissipation power from regenerative braking demand and a closed-loop controller to monitor actual battery power, correcting for estimation errors and ensuring safe energy absorption. This paper will also evaluate the usage of the control strategy for other powertrain architectures and battery electric vehicles (BEVs). Validation through 1-D simulation and Hardware-in-the-Loop (HIL) demonstrates that this strategy effectively manages energy, reduces brake system stress and maintains vehicle safety under demanding downhill conditions.