DA Converter Failure Detection via Inspection Current Frequency Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensor systems, such as air-fuel ratio and NOx sensor systems, cannot detect failures in the switching elements of the DA converter, leading to abnormal control currents and potential system malfunctions.
Innovation Solution
A sensor system that includes a DA converter, a control part, and additional components for generating and detecting an inspection current. This system uses frequency analysis of the temporal change in the difference between the detected inspection current and its expected value to detect failures in the DA converter's switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control current magnitude is determined using the control current instruction value without actual measurement, then the system complexity is reduced and processing is facilitated, but the ability to detect DA converter failures is lost
Solution Approach 1:
The patent applies preliminary action by performing failure detection measurements before normal operation or during dedicated inspection periods. The inspection current is applied in advance to test the DA converter's switching elements, allowing potential failures to be identified before they affect normal control operations. This separates the detection function from the control function, maintaining simplicity while enabling reliability monitoring.
Solution Approach 2:
The patent introduces an intermediary inspection current measurement system that acts as a mediator between the DA converter and the control unit. This intermediary measurement mechanism allows the system to indirectly assess the DA converter's health without requiring direct modification of the control current path. The inspection current serves as a test intermediary that reveals switching element states without disrupting normal operation.
2Measurement precision
If switching elements are added to the DA converter output stage to increase resolution, then the control current precision is improved, but the probability of component failure increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the relationship between inspection current instruction values and actual inspection current values. When a discrepancy is detected that indicates switching element failure, this feedback information is used to identify the specific failed component. The feedback mechanism allows the system to adapt to failures and maintain operational awareness without requiring redundant components.
Solution Approach 2:
The patent applies parameter changes by varying the inspection current instruction value across a range of values during the detection process. By changing the digital input parameters to the DA converter and observing the corresponding analog output responses, the system can identify switching element failures through pattern recognition. This parameter variation approach enables diagnostic capability without adding physical redundancy to the converter structure.
Data Source
AI summary
A sensor system includes a sensor element to which a control current is inputted, a DA converter to output the control current, and a control part configured to generate a control current instruction value and input the control current instruction value to the DAC, and further includes an instruction value generation part to sequentially generate an inspection current instruction value to be inputted to the DAC instead of the control current instruction value, an inspection current detection part to detect an inspection current value of an inspection current, an expected value calculation part to calculate an inspection current expected value, a difference value acquisition part to acquire a difference value between the inspection current value and the inspection current expected value, and a failure detection part to detect a failure of a bit in the DA converter, by frequency analysis of a temporal change of the difference value.