Power Supply System CID Activation Detection
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Solution Overview
Problem
In power storage devices, it is challenging to accurately detect the activation of a current interrupt device (CID) due to the lack of direct detection methods, which can lead to secondary failures such as sparks within the battery cell when a CID is activated, especially in vehicles like hybrid vehicles.
Innovation Solution
A power supply system with a control device that utilizes a current detecting unit and a voltage detecting unit to calculate variation lengths of actual and command currents, and switches the power storage device into a non-conducting state when the CID is activated, based on threshold values, to prevent overvoltage and detect CID activation accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current interrupt device (CID) is activated to interrupt the conduction path when internal pressure exceeds a prescribed value, then overvoltage of the power storage device is prevented, but it cannot be directly detected whether the CID has activated or not
Solution Approach 1:
The patent introduces an intermediary detection mechanism that monitors the electrical characteristics (current, voltage) of the power storage device to indirectly detect CID activation. Instead of directly detecting the mechanical state of the CID, the system uses electrical parameters as mediators to infer the activation state, thereby resolving the detection problem while maintaining the overvoltage prevention function.
Solution Approach 2:
The system implements feedback by continuously monitoring the electrical characteristics of the power storage device and comparing them against expected values. When deviations indicate CID activation, the system provides feedback to the control device, enabling timely detection and response to the activation event while maintaining the protective function of the CID.
2Productivity
If the vehicle continues to run with the CID being activated, then the vehicle can maintain operation, but a large voltage is applied to the CID which can cause a spark inside the battery cell, possibly inviting a secondary failure
Solution Approach 1:
The system performs preliminary detection of CID activation by monitoring electrical characteristics before dangerous voltage levels build up. By detecting activation early and taking preliminary protective actions (such as isolating the affected cell or reducing load), the system prevents the conditions that would lead to secondary failures while allowing the vehicle to continue operating safely.
Solution Approach 2:
The patent converts the potentially harmful situation of continued operation with activated CID into a beneficial outcome by using the electrical characteristic changes as diagnostic information. This information allows the control system to adjust operating parameters, redistribute loads, or implement protective measures that prevent secondary failures while maintaining vehicle operation.
3Measurement precision
If a voltage detecting unit is used to monitor the power storage device, then the system can detect voltage changes, but the voltage detecting unit may fail, leading to inability to detect CID activation
Solution Approach 1:
The patent applies local quality by implementing multiple detection units with different functions (voltage detecting unit, current detecting unit) at different locations in the electrical circuit. Each unit monitors specific local electrical characteristics, and the combination of these localized measurements provides redundant detection capability that maintains system reliability even if one unit fails.
Solution Approach 2:
The system utilizes parameter changes by monitoring multiple electrical parameters (voltage, current) rather than relying on a single parameter. When the voltage detecting unit fails, the system can still detect CID activation by analyzing changes in current characteristics or other electrical parameters, thereby maintaining detection capability through parameter substitution.
Data Source
AI summary
A power supply system has a power storage device and an ECU, and supplies driving electric power to a load device. The power storage device includes an interrupting device configured to interrupt a conduction path of the power storage device. The load device includes a voltage sensor for detecting a voltage applied to the load device, and supply of electric power from the load device to the power storage device is stopped in response to a failure of the voltage sensor. Where the voltage sensor has failed, the ECU determines presence or absence of activation of the interrupting device, based on a variation length of an actual current that is input to or output from the power storage device and a variation length of a command current set in accordance with requested electric power requested based on a user's operation.