Mannbay Battery Thermal Management
The innovative features and challenges addressed by the top-mounted shared battery thermal management system are as follows:
1) Dual Electronic Expansion Valve Control: Balancing expansion valve requirements is a challenge due to cooling demands of over 10 kW during battery charging vs. mere hundreds during discharging. The precision control of electronic expansion valves, with its extensive adjustment range, is beneficial. However, dual electronic expansion valve systems can generate interference; employing an appropriate control strategy and extensive experimentation mitigates this system issue.
2) Compressor and Batter Cooler Matching: As the compressor in the shared air conditioning system has higher cooling capacity than that required for the battery, if not well controlled, frequent compressor start-ups and shutdowns may occur, even risking liquid strike, impacting compressor reliability. Through theoretical calculations and prototype testing, a fitting compressor-batter cooler match was established; integrating control of compressor speed and condensing air volume effectively resolved this matching issue.
3) System Oil Return: The difficulty of oil return exists when the compressor operates at low frequency for extended periods. Mannbay developed an external oil separator system to address this oil return issue during compressor operation at low temperatures.
4) Integrated Controller Development: Building on the existing top-mounted air conditioner electrical control, an integrated control system for air conditioning and battery thermal management was developed. The inverter, converter, logic controller, and other key control components were integrated into a multi-purpose controller to meet operational control modes under different vehicle and battery needs, enhancing the reliability of the integrated system.