Lithium-Ion BMS PCB Layout for Heat Dissipation and Current Sharing
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Solution Overview
Problem
Lithium-ion battery management systems (BMS) face challenges in managing temperature rise due to high current requirements, leading to component failure and increased costs, especially in space-constrained applications where traditional heat sinking methods are ineffective.
Innovation Solution
A diagonal structure and arrangement of electronic components and heat sinking elements on the printed circuit board (PCB) within the BMS, utilizing diagonally oriented conductive plates and traces to enhance heat dissipation and ensure equal current sharing among components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional heat sinking methods (surface mount MOSFETs with copper traces or external heatsinks) are used, then thermal management is attempted, but the thermal management effectiveness is insufficient due to limited copper trace thickness or thermal resistance of connections
Solution Approach 1:
The patent transitions from planar heat sinking (2D copper traces on PCB surface) to three-dimensional heat sinking by stacking multiple PCB layers with conductive paths extending through the board thickness. This vertical dimensionality change enables significantly increased heat dissipation surface area without increasing the PCB footprint, directly resolving the contradiction between temperature management effectiveness and component reliability.
Solution Approach 2:
The patent embeds heat sinking functionality within the PCB structure itself by creating internal conductive paths and heat dissipation channels that are nested within the PCB layers. The MOSFETs are mounted on the PCB surface while their heat sinks extend into the PCB interior, nesting the thermal management function within the existing structural boundaries rather than requiring external attachments.
2Power
If multiple MOSFETs are used in parallel to handle large currents, then current handling capability increases, but ensuring equal current sharing among components becomes difficult
Solution Approach 1:
The patent implements localized current sensing and balancing circuits at each MOSFET node within the parallel configuration. By providing individual current measurement and control pathways for each component, the system ensures equal current distribution without requiring high manufacturing precision across the entire assembly. Each MOSFET receives tailored control signals based on its local operating conditions.
3Device complexity
If BMS components are arranged linearly on the PCB, then layout simplicity is maintained, but components cannot fit in space-constrained applications with adequate heat sinking
Solution Approach 1:
The patent resolves the space constraint contradiction by utilizing the vertical dimension through multi-layer PCB construction. Heat sinking paths extend through multiple PCB layers rather than spreading linearly across the surface, enabling compact PCB footprints while maintaining adequate thermal management capability for high-power MOSFETs in space-constrained battery applications.
4Temperature
If external heatsinks with mechanical fasteners and thermal grease are used, then heat sinking capability is improved, but thermal resistance of connections increases and space is consumed
Solution Approach 1:
The patent merges the heat sinking function with the PCB structure itself, eliminating the need for separate external heatsink components and their associated mechanical fasteners and thermal grease interfaces. The conductive paths are integrated directly into the PCB laminate, reducing connection thermal resistance and simplifying the overall assembly while maintaining effective heat dissipation capability.
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 diagonal arrangement allows for improved thermal management and equal current sharing, reducing the risk of component failure and cost while fitting into compact spaces, thereby enhancing the reliability and efficiency of the BMS.
Implementation Method 1
utilizing diagonally oriented conductive plates and traces to enhance heat dissipation
Implementation Method 2
each MOSFET or current sense resistor shares an equal portion of the battery current and dissipates a portion of the power resulting temperature rise
Data Source
AI summary
A battery management system (BMS) for use in a rechargeable battery includes a printed circuit board (PCB) having two or more electrically conductive metal plates, the two or more electrically conductive metal plates located adjacent to and spaced apart from each other on the PCB providing an electrically isolating gap between the two or more electrically conductive metal plates; and multiple electronic components of the BMS electrically connected between the two or more electrically conductive metal plates.