Electric Vehicle Battery Thermal Management System (BTMS)
The Electric Vehicle Battery Thermal Management System (BTMS) is one of the core systems, directly affecting the safety, performance, and lifespan of the entire vehicle.
Cooling Function
Heat Absorption: Driven by an electric pump, the coolant flows through liquid cooling plates within the battery pack (usually in contact with the battery modules), absorbing the heat generated by the battery.
Heat Dissipation: The high-temperature coolant, having absorbed heat, is pumped to the front radiator (air-cooled) or exchanges heat with the vehicle's air conditioning system (via a chiller), dissipating the heat to the outside air.
Circulation: The cooled coolant flows back into the battery pack, beginning the next cycle.
Heating Function
When the battery temperature is too low, the system can heat the coolant using a PTC heater (positive temperature coefficient thermistor).
The warmed coolant flows through the liquid cooling plates, acting like a "hot water bottle" to heat the battery.
Some advanced systems can also utilize waste heat generated by the electric drive system, recovering residual heat through plate heat exchangers for battery heating, improving energy efficiency.
The thermal management system mainly consists of the following components:
Liquid Cooling Plate
The core heat exchange component in direct contact with the battery module is typically made of aluminum with an internal flow channel design. Its design must balance heat dissipation power, reliability, and lightweight.
Coolant
Requires high thermal conductivity, insulation (to prevent short circuits), low viscosity, a wide operating temperature range, and good material compatibility. Ethylene glycol-water mixtures are commonly used (the ratio is adjusted according to antifreeze requirements), but pure organic alcohols and other dielectric fluids are also sometimes used.
Electric Pump
Provides the power for coolant circulation. Its speed is often adjustable to achieve on-demand supply and reduce energy consumption.
Heat Exchanger
Chiller
A heat exchanger connecting the coolant circuit and the air conditioning cooling circuit, used to enhance cooling.
Radiator
Located at the front of the vehicle, it dissipates heat from the coolant through airflow.
Plate Heat Exchanger
Used for heat exchange between different circuits, such as for waste heat recovery.
PTC Heater
A device that heats the coolant when heating is required.
Valve Body
(e.g., three-way valve, solenoid valve): Controls the flow direction of coolant, enabling switching between different modes (e.g., switching between cooling and heating modes, or between different heat sources).
Reservoir
Compensates for the expansion and contraction of coolant volume due to temperature changes and facilitates filling and bleeding.
Sensors and Control Units
Temperature sensors monitor battery and coolant temperatures in real time. The Battery Management System (BMS) thermal management controller is the brain, intelligently controlling the operation of actuators such as pumps, PTC, valves, and air conditioning compressors based on temperature signals and vehicle status using algorithms.
