Floating Capacitor Self-Diagnosis for Cell Balancing Circuit Abnormalities
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Solution Overview
Problem
Conventional methods for diagnosing abnormalities in cell balancing circuits require additional circuits and comparators, increasing manufacturing costs and complexity.
Innovation Solution
An apparatus using a floating capacitor charged with battery cell voltage, a cell balancing circuit for discharging the capacitor, and a control unit to measure residual voltage, determining abnormalities without additional circuits by comparing charged and discharged voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate diagnosis circuit with additional comparators is installed to detect abnormalities in the cell balancing circuit, then the reliability of abnormality detection is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The floating capacitor is designed to serve multiple functions: it is used for cell voltage measurement during normal operation and simultaneously serves as the test object for abnormality diagnosis. By measuring the discharge characteristics of this same capacitor, the system can detect cell balancing circuit abnormalities without requiring separate dedicated test capacitors or additional comparison circuits, thus reducing device complexity while maintaining diagnostic reliability
Solution Approach 2:
The cell balancing circuit performs self-diagnosis by using its own floating capacitor as the test subject. The control unit measures the discharge voltage of the capacitor that is already part of the cell balancing circuit, allowing the system to self-monitor its health status without external diagnostic equipment or additional circuitry, thereby simplifying the overall system architecture
2Object-affected harmful factors
If additional comparators and diagnosis circuits are added to monitor cell balancing circuit abnormalities, then the safety against battery pack explosions or load stoppages is improved, but the manufacturing cost increases
Solution Approach 1:
The floating capacitor performs dual roles as both the functional component for cell voltage measurement and the test object for safety monitoring. The control unit leverages existing measurement capabilities to assess capacitor discharge characteristics, eliminating the need for additional safety circuits or comparators. This approach maintains comprehensive safety monitoring while avoiding increased manufacturing costs associated with extra components
3Measurement precision
If conventional diagnosis methods using separate circuits are used, then the accuracy of cell balancing circuit diagnosis is improved, but the ease of manufacture deteriorates due to increased component count
Solution Approach 1:
The system achieves accurate diagnosis by having the cell balancing circuit test itself through its own floating capacitor. The control unit measures the discharge voltage characteristics of the capacitor that is already integrated into the circuit, obtaining precise diagnostic information without requiring separate test equipment. This self-testing approach maintains measurement precision while significantly simplifying manufacturing by eliminating additional diagnostic components
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
Enables simple and cost-effective diagnosis of cell balancing circuit abnormalities, preventing potential battery pack issues like explosions or sudden load stoppages.
Implementation Method 1
a floating capacitor (C1 and C2) charged with voltages of battery cells (V1 and V2)
Implementation Method 2
a cell balancing circuit (30A and 30B) for discharging the floating capacitors (C1 and C2)
Data Source
Figure 1~2
Figure 3
AI summary
Provided are an apparatus and a method for diagnosing an abnormality in a cell balancing circuit. The apparatus may include a floating capacitor charged with voltage of a battery cell, a cell balancing circuit for discharging the floating capacitor, a voltage measuring unit for measuring the battery cell voltage of the charged floating capacitor and a residual voltage of the discharged floating capacitor, and a control unit for determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.