Thermal management continues to be a key topic for electric vehicle (EV) design. Early trends in the market largely revolved around the adoption of active cooling for the battery pack, now this is the industry standard. However, batteries, motors, and power electronics in EVs continue to evolve with developments of cell-to-pack designs, directly oil-cooled motors, and silicon carbide power electronics being just a few of the key trends that will impact thermal management strategies across the key driveline components in an EV. As the thermal management market evolves, opportunities arise for materials companies, component suppliers, vehicle designers, and other players in the rapidly growing EV industry.
Battery: cell-to-pack, coolants, thermal interface materials, and fire protection
The key factors for EV battery development are increasing energy density and reducing costs. This strategy culminates in cell-to-pack or cell-to-body designs. Cell-to-pack eliminates strict module housings in favor of having all of the cells stacked together. Cell-to-body makes the battery a structural part of the vehicle. Designs from BYD, Tesla, and others have made it onto the road, with further announced designs coming to market in the near future.
Motor
For electric motors, the magnets used in the rotor and the windings used in the stator must be kept in an optimal operating temperature window to avoid damage or inefficient operation. Water glycol used in a jacket around the motor has been the standard thermal management strategy for electric motors in EVs. However, recent years have seen much greater adoption of directly oil cooling the motor to provide better thermal performance, and in some cases, eliminate the cooling jacket, reducing the overall motor size. Oil cooling became the dominant form of cooling for EV motors in the first half of 2022, but that’s not to say that water jackets are going away, they are often used in conjunction with oil cooling, and water-glycol coolant is typically used to remove heat from the oil and can be used to integrate with the vehicles thermal management strategy as a whole.
Power Electronics
The adoption of SiC is the largest trend in the news for EV power electronics and with good justification. The EV market provides a huge addressable market for the adoption of the wide bandgap semiconductor to enable higher system efficiencies. This has had an impact on the construction of power electronics packages. Developments are happening for wire bonding, die-attach, and substrate materials, largely with the goal of improving package reliability, especially for wide bandgap semiconductor modules. Many inverter suppliers have now eliminated the TIM between the heatsink and baseplate to improve thermal resistance, although this does not mean there are no TIM opportunities within power electronics.
