Integrated Vehicle Thermal Management for Advanced Vehicle Propulsion Technologies

Abstract

A critical element to the success of new propulsion technologies that enable reductions in fuel use is the integration of component thermal management technologies within a viable vehicle package. Vehicle operation requires vehicle thermal management systems capable of balancing the needs of multiple vehicle systems that may require heat for operation, require cooling to reject heat, or require operation within specified temperature ranges. As vehicle propulsion transitions away from a single form of vehicle propulsion based solely on conventional internal combustion engines (ICEs) toward a wider array of choices including more electrically dominant systems such as plug-in hybrid electric vehicles (PHEVs), new challenges arise associated with vehicle thermal management. As the number of components that require active thermal management increase, so do the costs in terms of dollars, weight, and size. Integrated vehicle thermal management is one pathway to address the cost, weight, and size challenges. The integration of the power electronics and electric machine (PEEM) thermal management with other existing vehicle systems is one path for reducing the cost of electric drive systems. This work demonstrates techniques for evaluating and quantifying the integrated transient and continuous heat loads of combined systems incorporating electric drive systems that operate primarily under transient duty cycles, but the approach can be extended to include additional steady-state duty cycles typical for designing vehicle thermal management systems of conventional vehicles. The work compares opportunities to create an integrated low temperature coolant loop combining the power electronics and electric machine with the air conditioning system in contrast to a high temperature system integrated with the ICE cooling system.

Light weight high temperature polymer film capacitors with dielectric loss lower than polypropylene

“…The thermal management issue is usually addressed by using special capacitor design to enhance heat dissipation, adding active cooling system, or using high temperature capacitor film. For example, with a melting temperature (T m ) of *170-175°C and thermal stability *105°C, semicrystalline BOPP film capacitors can only be continuously and reliably used in EDV power inverters with a secondary cooling system of *65°C for coolant temperature, rather than sharing the regular cooling loop with the engine radiator, which may have coolant temperature above 105°C [7][8][9]. The additional cooling loop not only adds significant cost, but also increases the system complexity and brings potential reliability concern.…”

“…However, the increase in power density has led to significant challenges in thermal management due to the adverse concurrent increase power loss density, which cannot be quickly dissipated for film capacitors because of the poor thermal conductivity in polymers, thus, leading to localized hotspots in the capacitor that are significantly hotter than the ambient temperature [7][8][9][10]. The thermal management issue is usually addressed by using special capacitor design to enhance heat dissipation, adding active cooling system, or using high temperature capacitor film.…”

Semicrystalline polymers with high dielectric constant, melting temperature, and charge-discharge efficiency

“…For example, with thermal stability at ~105 C, PP capacitors made with 3 m thick film with rated voltage up to 600 V can only be continuously used in HEV power inverters with a secondary cooling system set at ~65 C coolant temperature, rather than sharing the regular cooling loop with the engine radiator, which may have coolant temperature above 105 C. The additional cooling loop not only adds significant cost, but also increases the system complexity and brings potential reliability concern [4]- [6], [10], [11]. Therefore, new capacitor products with high energy density, power density, capacitance density, and thermal stability have to be developed to enable the practical applications of next generation power electronics in electric vehicles, wind turbine generators, grid-tied photovoltaics, smart grid, and aerospace [12]- [15].…”

High temperature capacitors with high energy density

“…[4]- [6], [8], [9] Therefore, new capacitor products with high energy density, power density, capacitance density, and thermal stability have to be developed to enable the practical applications of next generation power electronics in electric vehicles, wind turbine generators, grid-tied photovoltaics, smart grid, and aerospace. [10]- [13] Recently, extensive studies have been performed to improve the high voltage performance of PVDF-based polar fluoropolymers.…”