BMS MOSFET Overcurrent Detection Using Power and Junction Temperature
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Solution Overview
Problem
Existing battery management systems (BMS) face challenges in accurately detecting overcurrent events in switching devices like MOSFETs, which can lead to failure due to transient current spikes and historical power dissipation, leading to potential thermal runaway and device damage.
Innovation Solution
The BMS employs dual overcurrent detection techniques: OC1, which calculates average power dissipation over multiple time windows using exponential moving averages, and OC2, which models junction temperature based on historical power dissipation, to quickly disable the switching device before failure occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overcurrent detection is performed using existing techniques (average power over fixed time periods or instantaneous current thresholds), then overcurrent detection can be implemented, but the detection may not be sufficiently fast or accurate for rapidly changing power demands
Solution Approach 1:
The patent segments the overcurrent detection process into multiple parallel techniques: (1) average power calculation over multiple overlapping time periods, (2) instantaneous current threshold comparison, and (3) junction temperature monitoring. Each technique operates independently and contributes to the overall detection accuracy, allowing the system to detect overcurrent conditions through multiple pathways simultaneously, thereby improving both speed and precision.
Solution Approach 2:
The patent implements dynamic adjustment of detection parameters based on real-time conditions. The system dynamically selects and weights different detection techniques based on the current operating state, adjusting the time periods for average power calculation and threshold levels according to the battery's charge/discharge state, temperature, and load conditions. This dynamic approach enables faster and more accurate detection during rapidly changing power demands.
2Reliability
If multiple overcurrent detection techniques are implemented simultaneously, then detection accuracy and speed are improved, but the device complexity increases
Solution Approach 1:
The patent makes the existing BMS controller perform multiple functions: it calculates average power over different time periods, compares instantaneous current against thresholds, monitors junction temperature, and integrates results from all these techniques. By making the single controller multi-functional, the system achieves high detection reliability without adding separate dedicated hardware for each detection technique, thus managing complexity while improving reliability.
Solution Approach 2:
The patent merges multiple detection techniques and their processing logic into a unified control algorithm within the BMS controller. Rather than implementing separate independent systems for average power detection, instantaneous current detection, and temperature monitoring, the patent combines these functions into an integrated overcurrent protection system that processes multiple parameters simultaneously and makes unified protection decisions, reducing overall system complexity.
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 approach enhances the safety and reliability of BMS by accurately detecting overcurrent events, preventing switching device failure and reducing costly repairs.
Implementation Method 1
the second technique may detect OC2 based on determining a modeled junction temperature of a switching device
Data Source
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AI summary
Improved overcurrent detection and mitigation systems, methods, and techniques for a BMS are described herein. A BMS monitor may detect an overcurrent using two different techniques. The first technique may detect (OC1) an overcurrent based on average power over different, overlapping time periods. The second technique may detect (OC2) an overcurrent based on determining a modeled junction temperature of a switching device.