Multiplexer Self-Diagnosis via Fault Voltage Injection
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Solution Overview
Problem
Conventional battery control devices cannot self-diagnose faults in the switch selector of a multiplexer, which controls the switching operation between battery cells, as faults in the switch selector do not affect the cell voltages, making it impossible to detect abnormalities based on cell voltage measurements.
Innovation Solution
A voltage detection device with a multiplexer that includes an additional input channel for a fault detection voltage, allowing the device to self-diagnose the multiplexer controller by detecting the fault detection voltage at a timing different from the normal timing, enabling the detection of abnormalities in the switch selector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multiplexer with switch selector is used to monitor battery cell voltages, then the voltage monitoring function is achieved, but the switch selector cannot be self-diagnosed because faults in the switch selector do not affect the cell voltages
Solution Approach 1:
The patent applies preliminary action by introducing a known test voltage signal through the additional input channel before normal operation. The multiplexer controller is instructed to selectively connect this additional input channel to the output channel at predetermined timings, allowing the voltage detection device to detect whether the switch selector is functioning normally by comparing the detected test voltage with the expected value. This preliminary test signal injection enables fault detection of the switch selector without affecting normal voltage monitoring operations.
2Reliability
If an additional input channel is added to the multiplexer for fault detection, then the switch selector can be self-diagnosed, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the additional input channel to serve multiple functions: it can be connected to a test voltage source for switch selector diagnostics, and can also be configured to monitor additional battery cells or voltage points when not in test mode. The multiplexer controller intelligently manages the additional input channel, instructing the multiplexer to connect it to the output channel only at predetermined timings for fault detection purposes, while maintaining normal monitoring operations for all battery cells. This multi-functional design minimizes the impact on device complexity while enabling comprehensive self-diagnosis capability.
Data Source
AI summary
A voltage detection device including a multiplexer provided with a plurality of input channels connected to respective battery cells and an output channel connected to an analog-to-digital (AD) converter. The multiplexer is further provided with an additional input channel that is connected to a voltage source that supplies a fault detection voltage. A multiplexer controller is triggered by an input trigger signal to instruct the multiplexer to sequentially connect the input channels and the additional input channel to the output channel according to a predetermined voltage detection sequence. An abnormality detector determines that there exists an abnormality in the multiplexer controller on the basis of an output of the AD converter when the AD converter detects the fault detection voltage at a timing different from a normal timing defined by the voltage detection sequence. This enables the voltage detection device to self-diagnose the multiplexer controller.