Vehicle Battery Pack Switching for High-Temperature Power Limits
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Solution Overview
Problem
When multiple battery packs connected in parallel to a load operate at high temperatures, the total attainable output power is significantly limited due to the need to restrict current flow to protect the battery packs, leading to reduced power output.
Innovation Solution
A battery control system that includes a battery connection/disconnection section, an upper limit current calculation section, a current control section, an attainable output power comparison judgment section, and a battery connection/disconnection control section. This system dynamically adjusts the connection pattern of battery packs to maximize total attainable output power while ensuring each battery pack operates within its safe current limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current value of each battery pack is limited to protect high-temperature battery packs, then the reliability of battery packs is improved, but the total attainable output power of the battery module deteriorates
Solution Approach 1:
The battery module is divided into multiple independently controllable battery packs, each with its own contactor. This segmentation allows individual battery packs to be disconnected from the load when they exceed safe operating conditions, while other battery packs can continue to supply power. The control device calculates the upper limit current value for each battery pack based on its temperature and voltage, and selectively disconnects only those battery packs that would otherwise limit the total output power.
Solution Approach 2:
The system dynamically adjusts the connection state of each battery pack based on real-time temperature and voltage measurements. The control device continuously monitors battery pack conditions and dynamically determines which battery packs should be connected or disconnected to maximize total output power while maintaining safety. This dynamic adjustment allows the system to adapt to changing thermal conditions and optimize power output accordingly.
2Productivity
If all battery packs are connected in parallel to maximize power output, then the productivity is improved, but the temperature management and safety control become more complex
Solution Approach 1:
Each battery pack is equipped with its own temperature sensor and voltage detection circuit, enabling self-monitoring of operational conditions. The control device uses this self-reported data from each battery pack to automatically determine connection states, reducing the need for complex centralized control logic. Each battery pack essentially monitors itself and reports its status, simplifying the overall control architecture.
Solution Approach 2:
The system changes the operational parameters (connection state) of individual battery packs based on their temperature and voltage parameters. When a battery pack's temperature or voltage exceeds safe thresholds, its connection state changes from connected to disconnected. This parameter-based control approach provides a simple and effective method for managing multiple battery packs without requiring complex control algorithms.
Data Source
AI summary
A attainable output power comparison judgment section calculates a total attainable output power of a battery module using an upper limit current value of a battery pack for each of all connection patterns of a battery connection/disconnection section that are capable of being established between a plurality of battery packs and a load, and judges whether or not a high-output pattern exhibiting a total attainable output power higher than a total attainable output power of a present connection pattern exists. The battery connection/disconnection control section changes the battery connection/disconnection section from the present connection pattern to the high-output pattern when the attainable output power comparison judgment section judges that the high-output pattern exists.