With stringent emission norms enforced by governments and public authorities, advancements in internal combustion (IC) engine-based vehicles have become crucial. Cold starts and low-temperature combustion contribute significantly to vehicle emissions and need to be addressed to comply with upcoming stringent emission norms. An electric exhaust heater is known to reduce emissions by maintaining optimal exhaust temperature. For efficient energy management, exhaust heaters are typically powered by an onboard Energy Storage System (ESS), charged by electric machines. These electric machines in hybrid architecture provide efficient energy management by utilizing the recuperated braking energy of vehicles. However, the addition of a 48V hybrid system increases overall vehicle weight, and the vehicle effectiveness depends significantly on the vehicle application and ESS type used.
The focus of this study is to investigate the impact of mild hybrids on fuel economy and performance for different storage systems through system model analyses. Specifically, the study examines a P1 parallel hybrid vehicle equipped with 48V motor powering exhaust heater and 4 types of ESS: Lithium-Ion batteries, Lead Acid batteries, Super Capacitors, and Lithium-Ion Capacitors. A vehicle system model was developed in GT-ISE and analyzed to assess the impact of power limits, ESS specifications, and system sizes on the performance and economy of a 48V mild hybrid vehicle for standard drive cycles. Results indicate that higher power ESS enhances freight efficiency in drive cycles with high kinetic intensity, while for cruise drive cycles, the optimal ESS power is relatively low. Overall, the study evaluates the impact of ESS types, hybrid system sizing on vehicle performance and economy, proposing optimal hybrid system solutions for varied applications while ensuring compliance with stringent emission norms.
Keywords: Heavy Duty, Vehicle, Hybrid, EHPE, GT-SUITE, EV System Model, Freight Efficiency, ESS, Lithium-ion, Super Capacitor, Battery