A/D Converter Self-Diagnosis During High-Speed Sequential Sampling
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Solution Overview
Problem
Conventional A/D converter devices face challenges in detecting abnormalities promptly when used in high-speed sequential conversion applications, such as engine control systems, due to delayed reference voltage conversion, which can lead to erroneous control decisions.
Innovation Solution
An A/D converter device with a multiplexer, sample-hold section, and A/D converting section that alternately initializes and samples sensor signals while applying reference voltages during the conversion cycle, allowing for continuous operation and simultaneous self-diagnosis without interrupting the A/D conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the A/D converter device performs A/D conversion on reference voltage to judge abnormality, then abnormality detection capability is improved, but A/D conversion speed for sensor signals deteriorates due to delayed conversions
Solution Approach 1:
The patent applies preliminary action by performing abnormality detection using reference voltage conversion before or during the initialization phase of sensor signal conversions. The control unit is configured to judge abnormality based on A/D conversion results of reference voltage, and this judgment is made in advance or concurrently with setting up the conversion cycle for sensor signals, ensuring that abnormality detection does not delay the actual sensor signal processing.
Solution Approach 2:
The patent implements continuity of useful action by designing the A/D converter to continuously convert sensor signals at high speed while simultaneously or periodically performing reference voltage conversions for abnormality detection. The conversion cycle is structured so that reference voltage conversions are integrated into the overall conversion process without interrupting or significantly delaying the continuous stream of sensor signal conversions, maintaining both detection capability and conversion speed.
2Productivity
If the A/D converter device extends the interval between abnormality judgment conversions, then A/D conversion speed for sensor signals is improved, but abnormality detection timeliness deteriorates
Solution Approach 1:
The patent applies periodic action by configuring the control unit to perform reference voltage conversions for abnormality detection at regular intervals within the A/D conversion cycle. The judgment is made periodically based on these reference voltage conversions, ensuring that while not every sensor signal conversion is accompanied by a reference voltage conversion, abnormality detection occurs frequently enough to maintain timeliness. This periodic approach balances the need for fast sensor signal processing with timely abnormality detection.
Data Source
AI summary
The A/D converter device includes a comparing section and an abnormality judging section. The comparing section compares a voltage of its signal transfer line connected between its input multiplexer and its A/D converting section through its sample-hold section with a predetermined abnormality judging voltage. The abnormality judging section is configured to apply a reference voltage to the signal transfer line in synchronization with an A/D conversion cycle thereof on condition that its A/D converting operation thereof is not interrupted, and to determine presence of abnormality in the A/D converter device if an comparison result of the comparing section does not match an expected value corresponding to the reference voltage.