HEV Battery Management for Off-Board Power Delivery
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Solution Overview
Problem
Hybrid Electric Vehicles (HEVs) face repetitive and undesirable battery charging and depleting cycles when configured to supply off-board electrical power, leading to potential battery life degradation.
Innovation Solution
A closed-loop control system that monitors and adjusts the powertrain and battery charging-discharging subsystems to minimize the difference between off-board power delivery and internal/external electrical loads, ensuring optimal battery charge-discharge cycling and preventing depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the HEV supplies off-board electrical power from the battery, then off-board power delivery capability is improved, but repetitive battery charging and depleting cycles occur causing battery life degradation
Solution Approach 1:
The controller continuously monitors the state of charge (SoC) of the battery and the power being delivered to off-board loads. Based on this feedback, the controller dynamically adjusts the charging and discharging rates to maintain SoC within a predefined optimal range, preventing excessive cycling that would degrade battery life while still enabling off-board power delivery.
Solution Approach 2:
The system dynamically adjusts battery operating parameters (charging rate, discharging rate, and SoC thresholds) based on real-time conditions including off-board power demand, vehicle powertrain state, and battery health status. This dynamic control enables the system to adapt to varying load conditions while maintaining optimal battery charge levels and minimizing harmful cycling.
2Adaptability or versatility
If the battery is used to supply off-board electrical loads, then external power supply capability is improved, but undesirable battery charge-discharge cycling increases
Solution Approach 1:
The controller uses feedback from SoC sensors and power monitoring systems to detect when the battery is being excessively cycled during off-board power delivery. The feedback loop adjusts charging parameters in real-time to minimize the frequency and amplitude of charge-discharge cycles, thereby reducing wear while maintaining the ability to supply external power when needed.
Solution Approach 2:
The system changes operational parameters such as the minimum and maximum SoC thresholds, charging voltage, and discharging current limits based on the off-board power delivery mode. By dynamically adjusting these parameters, the system reduces unnecessary cycling while preserving the adaptability to provide external power supply when required by the application.
Data Source
AI summary
A hybrid electric vehicle includes an internal-combustion engine (ICE) and an electric machine coupled to a battery, an off-board power (OBP) system, and a controller, which are configured to power internal vehicle and battery charge electrical loads, and external electrical loads. The controller monitors the electrical loads, and responds to an OBP signal identifying an external electrical load, and commands the ICE and electric machine to generate a combined-power greater than or equal to the loads. This ensures that a battery state-of-charge is sustained and not depleted by power delivery to the external loads. The controller also generates a power-difference signal that identifies a difference between power generated by the electric machine and power consumed by the internal and external OFB electrical loads, such that the controller can adjusted the generated combined-power to minimize the power-difference signal and battery charge-discharge-cycles.