Hybrid Vehicle Battery Heating Control for Cold-Start Charging
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Solution Overview
Problem
In hybrid electric vehicles, charging the traction battery at low temperatures can lead to increased internal resistance and deterioration, particularly in lithium-ion batteries, due to high charging currents, which can cause lithium deposition.
Innovation Solution
A control method that includes cutting off the connection between the generator and the traction battery when the temperature is below a predetermined threshold, charging an auxiliary battery with generated power, and using an electric heater to raise the traction battery temperature until it exceeds a higher threshold, while consuming excess power in optional vehicle devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the generator charges the traction battery at low temperatures, then the electric power balance is maintained, but the traction battery deteriorates due to increased internal resistance and lithium deposition
Solution Approach 1:
The patent introduces an auxiliary battery as an intermediary component between the generator and the traction battery. When the traction battery temperature is below the first threshold, the relay cuts off direct charging connection, and the auxiliary battery serves as a buffer to receive generated electric power instead, preventing direct charging of the cold traction battery while maintaining overall power balance in the system.
Solution Approach 2:
The patent extracts the charging function from the direct generator-to-traction battery path by using the relay to cut off the connection when temperature conditions are not met. This separation allows the system to prevent harmful charging while exploring alternative power management paths through the auxiliary battery and heater.
2Reliability
If the relay cuts off the generator connection to the traction battery at low temperatures, then battery deterioration is suppressed, but the electric power balance is disrupted
Solution Approach 1:
The auxiliary battery acts as a mediator to absorb the electric power generated by the generator when the relay cuts off the direct connection to the traction battery. This ensures that the generated power is not wasted and can be used later when the traction battery temperature is appropriate, thereby maintaining overall electric power balance in the system.
Solution Approach 2:
The system performs preliminary heating of the traction battery using the electric heater before allowing charging to occur. By raising the battery temperature above the first threshold through preliminary heating action, the system prepares the battery to accept charge without deterioration, thus resolving the power balance issue while protecting battery durability.
3Reliability
If the electric heater raises the traction battery temperature, then the input/output performance is recovered, but additional electric power is consumed
Solution Approach 1:
The patent converts the harmful effect of low battery temperature (which causes high internal resistance and poor performance) into a beneficial situation by using the electric heater to raise the temperature. The same electric power that would have been wasted or caused deterioration at low temperatures is now used productively to heat the battery, improving its performance and enabling efficient charging operations.
4Productivity
If the relay remains connected at low temperatures, then charging efficiency is maintained, but lithium deposition occurs and battery life decreases
Solution Approach 1:
The system implements temperature-based feedback control through the relay. The relay continuously monitors the traction battery temperature and automatically adjusts the charging connection state based on whether the temperature exceeds the first threshold. This feedback mechanism ensures that charging only occurs when temperature conditions are appropriate, preventing lithium deposition while maintaining charging efficiency when conditions are favorable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach suppresses traction battery deterioration, maintains electric power balance, and ensures early recovery of input/output performance by raising the battery temperature, allowing satisfactory vehicle operation.
Implementation Method 1
supply the electric power generated by the generator to the electric heater to raise the temperature of the traction battery
Data Source
AI summary
Provided is a vehicle including an internal combustion engine, a generator a traction battery, a relay, an electric motor, an auxiliary battery, an electric heater, and a controller. The controller is configured to place the relay in a cut-off state when, at the time of the internal combustion engine being started, temperature of the traction battery is lower than a first predetermined temperature, and charging the auxiliary battery with electric power generated by the generator, and supply the electric power generated by the generator to the electric heater to raise the temperature of the traction battery, until the temperature of the traction battery exceeds a second predetermined temperature that is higher than the first predetermined temperature.