Fast EV charging requires high current flow, generating significant heat and cell imbalances in battery packs. Modern EV chargers and onboard chargers must utilize active cell balancing and liquid cooling systems to preserve battery life and safety.
Thermal Runaway and Capacity Loss
Charging batteries at high currents can cause excessive heat buildup and local hot spots. Furthermore, charge imbalances among cells in a series string lead to capacity loss and reduce overall pack safety if left unchecked.
Active Balancing, Liquid Cooling, and BMS Isolation
EV chargers and BMS architectures combine active cell balancing with fluid thermal management to secure safety:
- Active Cell Balancing: Transferring energy from higher-charge cells to lower-charge cells using capacitive or inductive converters.
- Liquid Cooling Loop Control: Regulating active coolant pump speed dynamically based on cell temperature sensors.
- High-Voltage Isolation: Utilizing isolated BMS communication lines to prevent electrical noise coupling between power stages.
- Precise SoC and SoH Algorithms: Running advanced State-of-Charge and State-of-Health estimations to optimize charging profiles.
Charger Simulation and Testing Frameworks
Thermal and balance flows are designed and tested using MATLAB Simulink, Ansys Fluent (for fluid dynamics), and high-voltage HIL hardware simulators.
Conclusion
EV charging systems must integrate cell balancing with thermal control. Active energy transfer combined with dynamic liquid cooling secures battery safety and extends cycle life.