Battery String Thermal Control Using Predicted Heat Loads
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Solution Overview
Problem
Energy storage systems face significant temperature imbalances due to varying external conditions, sun loading, and HVAC performance issues, leading to reduced battery life and delayed cooling responses, especially in lithium-ion batteries which operate optimally between 20°C to 25°C.
Innovation Solution
A temperature control system that includes a HVAC system and a controller programmed to predict heat loads for battery strings, determining DC/DC converter and HVAC operating commands to manage actual heat loads, and adjusting operations based on weather forecasts and local solar radiation measurements to maintain optimal temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single HVAC system is used for thermal management of multiple battery racks, then device complexity is reduced, but temperature imbalance among racks increases
Solution Approach 1:
The system divides the thermal management function into multiple independent HVAC units, each responsible for specific battery racks or zones. This segmentation allows each unit to independently control temperature in its designated area, eliminating temperature imbalances while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Each HVAC unit is equipped with local temperature sensors and control systems that independently monitor and adjust temperatures for their specific battery racks. This local quality approach ensures that each zone maintains optimal temperature conditions tailored to its specific thermal characteristics, preventing temperature imbalances across different racks.
2Quantity of substance
If battery capacity is increased to store more energy, then energy storage capability is improved, but thermal management difficulty increases
Solution Approach 1:
Large battery energy storage systems are divided into multiple smaller battery racks, each with dedicated HVAC control. This segmentation allows independent thermal management of each rack, making it easier to control temperatures in high-capacity systems without overwhelming thermal management complexity.
Solution Approach 2:
The system implements continuous temperature monitoring with feedback control loops that adjust HVAC operation based on real-time thermal conditions. Temperature sensors in each battery rack provide feedback to their dedicated HVAC units, enabling dynamic adjustment of cooling/heating to maintain optimal temperatures as battery capacity and thermal conditions vary.
3Duration of action of stationary object
If battery operating temperature is maintained in optimal range, then battery life is extended, but energy consumption for thermal management increases
Solution Approach 1:
The HVAC system uses temperature feedback control to maintain battery temperatures within the optimal 20-25°C range. Temperature sensors continuously monitor battery temperature and adjust HVAC operation accordingly, consuming energy only when needed to correct temperature deviations, thus extending battery life while minimizing unnecessary energy consumption.
Solution Approach 2:
The system dynamically adjusts HVAC operating parameters such as cooling capacity, airflow rates, and operational timing based on actual battery temperature conditions, ambient temperature, and battery load states. This parameter adjustment allows the system to maintain optimal battery temperatures for extended life while optimizing energy consumption by avoiding over-cooling or unnecessary operation.
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 balances thermodynamic performance in energy storage systems, extending battery life by maintaining optimal temperature ranges and reducing heat-related degradation, while also improving response times to cooling demands.
Implementation Method 1
response times to required cooling may sometimes be delayed by heat transfer considerations associated with the large thermal mass of the batteries
Implementation Method 2
Energy storage systems experience and generate heat. In particular, the greatest amount of heat is generated during charging and discharging of the batteries
Data Source
AI summary
An energy storage system includes a DC bus; a plurality of battery strings, each battery string comprising batteries coupled electrically together; a plurality of DC/DC converters electrically coupling respective battery strings to the DC bus; an enclosure housing the battery strings and the DC/DC converters; and a temperature control system. The temperature control system includes at least one heating, ventilation, and air conditioning (HVAC) system, and a controller. The controller is programmed to execute a method of predicting heat loads for respective battery strings within the enclosure, wherein the heat loads comprise external heat loads and internal heat loads; determining one or both of DC/DC converter operating commands and HVAC operating commands based on the respective predicted heat loads to control the actual heat loads of the respective battery strings; and operating one or both of the DC/DC converter and the HVAC system in response to at least one of the DC/DC converter operating commands and the HVAC operating commands.