Battery Pack Cell-Voltage Switching for Disconnection Diagnosis
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Solution Overview
Problem
Existing battery packs face challenges in diagnosing malfunctions, particularly disconnections in wiring paths leading from battery cells to voltage detectors, which can occur due to vibrations and impacts commonly encountered in outdoor equipment.
Innovation Solution
A battery pack design incorporating multiple switches, a voltage detection circuit, and a diagnosis circuit that detects cell voltages before and after switching states to identify disconnections by analyzing voltage changes, and adjusts cell voltages to balance them, using transistors and fuses to ensure accurate diagnosis and prevent further damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are provided in parallel paths with battery cells to enable voltage detection and balancing, then the ability to diagnose disconnections and balance cell voltages is improved, but the device complexity increases due to additional components and diagnosis circuits
Solution Approach 1:
The switches serve multiple functions: they enable voltage detection by providing access to cell voltages, perform cell balancing by controlling current paths, and facilitate diagnosis by allowing controlled on/off states for comparison. This multi-functionality reduces the need for separate dedicated components for each function.
Solution Approach 2:
The diagnosis circuit uses the existing voltage detection circuit and switches to perform self-diagnosis. By controlling the switches to specific on/off states and comparing voltage detection results across different states, the system can autonomously identify disconnections without requiring external diagnostic equipment.
2Reliability
If voltage detection is performed continuously to enable real-time diagnosis, then the diagnosis speed and reliability are improved, but the energy consumption increases
Solution Approach 1:
Instead of continuous voltage detection, the system performs periodic detection by switching between different switch states at predetermined intervals. The diagnosis circuit controls switches to be in specific on/off states during detection periods, then transitions to other states, creating a periodic detection pattern that reduces energy consumption while maintaining diagnostic capability.
Solution Approach 2:
The system performs preliminary voltage detection by switching to a detection-friendly state before actual operation, then uses the detected values for diagnosis. This allows the system to check voltages in advance without maintaining continuous detection during all operational states, thereby reducing overall energy consumption.
Data Source
AI summary
A battery pack includes a storage battery, multiple switches, a voltage detection circuit, and a diagnosis circuit. The storage battery includes multiple battery cells coupled in series. The switches correspond to the respective battery cells and are each provided in a first parallel path of corresponding one of the battery cells. The voltage detection circuit is configured to detect respective voltages across the switches, as multiple cell voltages corresponding to the respective battery cells. The diagnosis circuit is configured to put one or more of the switches into an on state in a predetermined period, and configured to perform a diagnosis process based on a detection result of the voltage detection circuit before the predetermined period and a detection result of the voltage detection circuit after the predetermined period.