Hybrid Vehicle Controller Battery Thermal Management
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Solution Overview
Problem
Mild-hybrid vehicles face challenges in maintaining battery performance and enabling start-stop functions in cold climates due to reduced battery power and current capability at low temperatures, which limits torque assist and cranking capabilities.
Innovation Solution
A controller-based protocol that utilizes the integrated starter-generator to provide torque assistance and charge the battery at optimized power limits, leveraging cabin air warming and regenerative braking to efficiently warm the battery pack to operational temperatures, thereby enabling cranking functions even in cold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the battery operates in cold climates, then the vehicle can maintain mobility, but the battery power and current capability are reduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power limit of the electric machine based on battery temperature. When the battery temperature is below a threshold, the controller reduces the power limit to prevent excessive current draw that would further cool the battery. This adaptive parameter adjustment resolves the contradiction by allowing the battery to operate at reduced power in cold conditions, maintaining mobility while preventing thermal degradation.
Solution Approach 2:
The system implements dynamics by continuously monitoring battery temperature and adjusting the electric machine's power output in real-time. The controller dynamically modifies the torque assistance capability based on thermal conditions, transitioning between different operational states. This dynamic response allows the system to optimize performance while protecting the battery from cold-temperature stress.
2Productivity
If the electric machine provides torque assistance at high power, then vehicle acceleration is improved, but battery temperature drops further in cold conditions
Solution Approach 1:
The patent implements feedback control by continuously monitoring battery temperature and using this information to adjust the electric machine's torque assistance output. The controller receives temperature feedback and modifies the power limit accordingly, creating a closed-loop system that balances acceleration performance with thermal management. This feedback mechanism resolves the contradiction by preventing high-power operation when it would cause harmful temperature drops.
3Reliability
If the battery state of charge is maintained above a high threshold, then start-stop functions are enabled, but the SOC threshold is too high for cold conditions
Solution Approach 1:
The patent applies parameter changes by adjusting the SOC threshold based on battery temperature. When the battery is cold, the controller lowers the SOC threshold required to enable start-stop functions, allowing these functions to become available at lower charge levels than would be permitted in warm conditions. This resolves the contradiction by adapting the threshold parameter to thermal conditions, enabling start-stop operation when appropriate while maintaining fuel economy.
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 effectively restores battery power capability, enabling start-stop operations and improving fuel economy by gradually warming the battery pack without causing degradation, thus enhancing vehicle performance and drivability in cold climates.
Implementation Method 1
an electric machine coupled to the powertrain and a battery
Implementation Method 2
enable the electric machine to charge the battery
Implementation Method 3
a battery, and a controller
Data Source
AI summary
A vehicle includes a controller that is configured to, while a battery temperature exceeds a threshold and state of charge (SOC) is above an SOC threshold, enable an electric machine to provide torque assistance at a power limit, and responsive to the temperature dropping below the threshold, increase the power limit and enable the electric machine to provide torque assistance while the SOC is above a cold SOC threshold less than the SOC threshold.