Keeping It Cool: Electric Vehicles Testing

The compressor is a critical component for cooling systems and their significance drastically increases in the EV space. Within EV, the compressor cools the battery and the cabin of the vehicle.  Testing an EV compressor is essential for performance and becomes increasingly complex as more variables are introduced into the mix. As much as engineers can design around parameters that affect the compressor as an individual component, there are many external factors that are driven by the OEM that can have an impact on the performance of the system as a whole. For example, if you look at an HVAC system, the compressor controls the flow of the refrigerant through the system, but other factors such as spacing, alignment, size and surface area of other components all contribute to the overall performance of the system in a vehicle.
Any manufactured product should be tested under worst-case conditions in order to determine longevity, durability and performance. Compressors—and other components—are no exception. With component and systems testing, engineers are able to determine the durability and performance of the compressor, but how it performs out in the real world is a whole other ball game.
With standard internal combustion engine vehicles, worst-case scenario is when the engine is running under extreme environmental influence. When it comes to EVs, however, there are a new set of factors to consider. In addition to HVAC, cooling systems must be able to handle the load of battery cooling. Cooling is even more critical in electric vehicles because everything is powered by central battery packs and if the batteries fail the vehicle can no longer operate.

Charging electric vehicles also adds a substantial cooling burden to the configuration. DC fast charging is a key selling point for EVs in today’s market—how fast the vehicle can charge during road trips in a consideration for many consumers. DC fast charging increases the power input of the system to expedite charging times, but in doing so generates more heat and puts stress on the system. DC fast charging in the summer is one of the highest cooling loads an electric vehicle will experience and components need to be designed accordingly. In short, replicating real-world scenarios for electric vehicles must consider charging impact in addition to environmental influence.
As of now, several vehicles charge at up to 150kW, some at 250kW, and heavy-duty vehicles may require even higher rates to charge larger batteries. In fact, charging has such an impact on cooling systems that some DC fast charging modules are now seeing such a heat load from faster charging rates that they themselves require technology to cool the device that is charging the vehicle. As the EV market continues to expand and evolve, the importance of testing cannot be overstated. Electric compressor performance is critical not just to the cabin temperature, but the overall functionality of the vehicle.