Electric Vehicle Thermal Management
Cooling Needs
One of the cooling needs: high-voltage battery cooling
The battery itself due to the existence of internal resistance and discharge equalization circuit, the current flowing during charging and discharging will cause the battery to heat up, and the spontaneous combustion incident mentioned at the beginning of the article has a shadow of this part.
The longer the continuous driving time, the more acceleration and deceleration, the greater the intensity of acceleration and deceleration, are promoting the battery heating.
Battery heating is also different according to different cars and different batteries, for example, some micro cars or small cars itself charging and discharging power is not large, the continuous heating of the battery will not be too large, at this time the use of some air-cooled way or smaller water-cooled cooling circuit can be;
Cooling needs of the second: high-voltage power electronic cooling
Three electricity in addition to the battery is the motor and electric control, in fact, there are car charger OBC (OnBoard Charger), high-voltage to low-voltage DC / DC and high-voltage distribution box also has cooling needs.
In many models, because the power electronic composition of these power devices are relatively the same, only the power size of each other and different internal design, such as electronic control, car charger and DC/DC will use IGBT insulated gate bipolar transistor, its heat power and switching speed, and its switching speed also directly affects the output power of these power electronics.
DC/DC depending on the composition of the low-voltage actuator, generally between 2 to 3kW, efficiency is also in 95%, then from the start of the supply of low-voltage parts, DC/DC stable heat generation is also close to 150W.
These heat if accumulated in the OBC and DC/DC will inevitably lead to parts temperature rise, and these parts suppliers to protect the components will be in the temperature exceeds a certain threshold to limit the power output at the same time to the entire vehicle controller overheating warning.
This is especially true for motors and electronic controls, which are familiar with the efficiency diagram of motors. Based on different output torques and speeds, motors and electronic controls will suffer corresponding heat losses, and the total heat can reach the kilowatt level, which are expected to be brought out of the component body by the thermal management system.
Cockpit Cooling
Some of the latest technologies are water-cooling of the charging cable from the DC charging station end, and the cooling circuit is circulated in the DC charging pile; some propose to use the cooling cycle inside the car and the outer ring of the cable to achieve water cooling. Regardless of which method is essentially helping the realization of high-power charging, but it seems that the complexity and the cost behind it are relatively large. It can be seen that in the future to really implement high-power charging there are still many unproductive technology needs to be landed.
