Battery Pack Self-Heating via DC/DC Charge-Discharge Cycling
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Solution Overview
Problem
Conventional methods for heating lithium-ion batteries in low-temperature environments result in non-uniform heat transfer, low heating efficiency, and increased complexity due to the use of external heating components like heating films or PTC heaters, which also risk thermal runaway and lithium dendrite formation.
Innovation Solution
A battery system with a battery management system that includes a sampling control unit, DC/DC conversion unit, and energy storage unit, which controls charge and discharge cycles to achieve uniform heating through the Joule thermal effect, avoiding lithium precipitation and reducing the risk of short circuits, while maintaining a simple structure and high applicability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating film or PTC heater is used to heat the battery, then the battery temperature can be increased, but the heat transfer is non-uniform and heating efficiency is low
Solution Approach 1:
The battery pack serves itself for heating by utilizing its own internal energy storage units and DC/DC conversion unit to generate heat through controlled charge-discharge cycles, eliminating the need for external heating components and achieving uniform heat generation throughout the battery pack
Solution Approach 2:
The heating is achieved through periodic charge-discharge cycles of the energy storage units, where the DC/DC conversion unit repeatedly charges and discharges the batteries at controlled intervals, generating uniform heat through resistive heating during each cycle while maintaining temperature control
2Temperature
If heating film or PTC heater is used to heat the battery, then the battery temperature can be increased, but the system structure becomes complex and volume increases
Solution Approach 1:
The energy storage units and DC/DC conversion unit serve multiple functions: they provide power management for the battery pack, enable controlled heating through charge-discharge cycles, and can also supply power to external loads, eliminating the need for separate heating components and reducing system complexity
Solution Approach 2:
The battery pack uses its own existing components (energy storage units and DC/DC conversion unit) to perform the heating function, making the system self-sufficient and avoiding the addition of external heating devices, thereby maintaining simple structure and high applicability
3Temperature
If conventional heating methods are used, then heating can be achieved, but the heating speed is slow
Solution Approach 1:
The rapid heating is achieved through high-frequency periodic charge-discharge cycles of the energy storage units, where the DC/DC conversion unit rapidly switches between charging and discharging modes, generating heat quickly through resistive heating during each cycle
Solution Approach 2:
The heating process maintains continuous useful action by keeping the energy storage units in constant charge-discharge cycles without interruption, ensuring continuous heat generation and rapid temperature increase throughout the battery pack
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
The system achieves improved heating efficiency and speed, ensures energy maximization, safety, and high applicability by self-heating the battery pack from the inside out, allowing for fast charging and discharging while preventing lithium precipitation and thermal runaway.
Implementation Method 1
controls charge and discharge cycles to achieve uniform heating through the Joule thermal effect
Data Source
AI summary
A battery management system includes a sampling control unit, a DC/DC conversion unit, and an energy storage unit. When the battery pack needs to be heated, based on battery parameters of the battery pack and a voltage and a current limit value of the DC/DC conversion unit, the sampling control unit may control, in each of at least one consecutive first cycle, the battery pack to discharge to the energy storage unit by using the DC/DC conversion unit; control, in each of at least one consecutive second cycle, the energy storage unit to charge the battery pack by using the DC/DC conversion unit; and control, in the at least one consecutive first cycle and the at least one consecutive second cycle, an average charge/discharge current value of the battery pack to be less than or equal to a charge/discharge current limit value.