Fault Detection Apparatus Using Constant Resistance Isolation
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Solution Overview
Problem
Existing fault detection methods for sensor circuits in power conversion apparatuses, such as those in vehicles, suffer from low accuracy due to temperature changes affecting sensor output, making it difficult to determine faults reliably.
Innovation Solution
A fault detection apparatus that includes a sensor circuit, a signal output part generating a predetermined signal value, a changeover circuit connecting the signal output part with the sensor circuit, and a control part using a diagnostics signal to detect faults, employing a resistor with a constant resistance value to enhance detection accuracy by isolating the temperature sensor during diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is connected with a ground via a resistance element for fault detection, then fault detection capability is provided, but temperature changes cause output variations that reduce detection accuracy
Solution Approach 1:
The patent introduces a switch circuit as an intermediary component that can selectively connect either the temperature sensor or a constant resistance element to the sensor circuit. This mediator allows the system to isolate the temperature sensor during fault detection and use a stable resistance element instead, eliminating temperature-induced output variations while maintaining fault detection capability.
Solution Approach 2:
The patent changes the resistance parameter by switching between two different resistance elements: the temperature sensor's resistance (which varies with temperature) and a constant resistance element (whose resistance remains stable). This parameter change allows the system to select the appropriate resistance characteristic based on whether temperature measurement or fault detection is the current objective.
2Device complexity
If the temperature sensor is used for both normal operation and fault diagnostics, then device complexity is reduced, but fault detection accuracy deteriorates due to temperature-induced output variations
Solution Approach 1:
The patent makes the switch circuit multi-functional by enabling it to perform two distinct roles: during normal operation, it connects the temperature sensor for temperature measurement, and during fault diagnostics, it connects the constant resistance element for accurate fault detection. This universal component resolves the contradiction by allowing the system to have both simplicity and accuracy through a single integrated switching mechanism.
Data Source
AI summary
An object of the present invention is to enhance fault detection accuracy offered by a fault detection apparatus. A microcomputer reads a characteristic signal input thereto. The microcomputer compares a characteristic read from the characteristic signal with a previously established reference value. The previously established reference value represents a characteristic exhibited by a resistor that is connected with a temperature sensor circuit when the temperature sensor circuit operates normally. The microcomputer determines whether the characteristic exhibited by the resistor falls within a detection range. If it is determined that the characteristic falls with the detection range, the temperature sensor circuit is detected to be operational and information indicating that the temperature sensor circuit is operational is output to a host control apparatus. If it is determined that the detection range is exceeded, the temperature sensor circuit is detected to be faulty and information indicating that the temperature sensor circuit is faulty is output to the host control apparatus.