Traction Battery Warm-Up Control for Cold-Start Hybrid Vehicles
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Solution Overview
Problem
In hybrid electric vehicles, low traction battery temperatures increase internal resistance, reducing charging capacity and leading to premature deterioration, especially when lithium-ion batteries are charged with high currents at low temperatures, causing lithium deposition and accelerated degradation.
Innovation Solution
A vehicle system comprising a generator, internal combustion engine, traction battery, relay, auxiliary battery, electric heater, and controller, where the relay cuts off the generator's connection to the traction battery at low temperatures, charging the auxiliary battery and using excess power to heat the traction battery with an electric heater until it reaches a higher temperature, thus preventing deterioration and maintaining electric power balance.
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 lithium deposition and increased internal resistance
Solution Approach 1:
The auxiliary battery serves as an intermediary component between the generator and the traction battery. When the traction battery temperature is below the first threshold, the controller directs generator output to charge the auxiliary battery instead of the traction battery, preventing harmful charging while maintaining overall electric power balance in the system
Solution Approach 2:
The system replaces the direct electrical charging path (generator to traction battery) with an alternative path through the auxiliary battery and electric heater. This substitution allows the system to avoid the harmful effects of low-temperature charging while still managing energy flow appropriately
2Productivity
If the electric heater raises the traction battery temperature, then the charging efficiency improves, but the energy consumption increases
Solution Approach 1:
The electric heater is activated before charging operations to raise the traction battery temperature above the first threshold. This preliminary heating action ensures that subsequent charging occurs at optimal temperatures, preventing the need for repeated heating cycles and improving overall charging efficiency
Solution Approach 2:
The controller continuously monitors the traction battery temperature and adjusts the electric heater operation accordingly. When the temperature exceeds the first threshold, the heater is deactivated, creating a feedback-controlled system that minimizes energy consumption while maintaining optimal charging conditions
3Productivity
If the relay remains connected at low temperatures, then the charging process continues, but the battery deterioration accelerates due to high internal resistance
Solution Approach 1:
The auxiliary battery acts as an intermediary energy storage device that allows the relay to remain connected in the system while redirecting the charging current away from the traction battery. This maintains system connectivity and charging process continuity while protecting the traction battery from harmful low-temperature charging effects
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 solution effectively suppresses traction battery deterioration, recovers input/output performance, and enables early vehicle travel by maintaining an appropriate electric power balance and raising the battery temperature, ensuring efficient charging and operation.
Implementation Method 1
supplying the electric power generated by the generator to the electric heater to raise the temperature of the traction battery
Data Source
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AI summary
Provided is a vehicle (1) including an internal combustion engine (10), a generator (30), a traction battery (80), a relay (90), an electric motor (40), an auxiliary battery (110), an electric heater (130), and a controller (300). The controller (300) is configured to place the relay (90) in a cut-off state when, at the time of the internal combustion engine (10) being started, temperature of the traction battery (80) is lower than a first predetermined temperature, and charging the auxiliary battery (110) with electric power generated by the generator (30), and supply the electric power generated by the generator (30) to the electric heater (130) to raise the temperature of the traction battery (80), until the temperature of the traction battery (80) exceeds a second predetermined temperature that is higher than the first predetermined temperature.