Power Converter Failure Detection Using Adjacent Sensor Pairs
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Solution Overview
Problem
Existing failure detection devices for power converters in vehicles, particularly in low refrigerant flow rate conditions, are prone to erroneous temperature sensor failure detection, which can lead to incorrect failure determination and reduced ability to detect actual failures in normal conditions.
Innovation Solution
A failure detection device that selects pairs of temperature detection members for adjacent switching elements, calculates the absolute difference in their detection values, and determines a failure only when the absolute value exceeds a predetermined threshold, thereby reducing erroneous detection and improving accuracy even in low refrigerant flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threshold value is increased to avoid erroneous detection in low refrigerant flow rate conditions, then false failure detection is reduced, but the ability to detect actual failures in normal conditions deteriorates
Solution Approach 1:
The patent applies local quality by selecting specific pairs of temperature detection members based on their spatial relationship (adjacent switching elements) rather than uniformly applying threshold comparison to all sensor pairs. This localized approach focuses the detection on regions where temperature gradients are most informative for failure detection, thereby maintaining sensitivity without increasing false positives.
Solution Approach 2:
The patent changes the detection parameter from absolute temperature comparison to differential temperature comparison between adjacent sensors. By monitoring the temperature difference (ΔT) between paired sensors rather than absolute temperatures, the system becomes insensitive to ambient temperature variations and refrigerant flow rate changes, while remaining sensitive to actual sensor failures that cause abnormal temperature differentials.
2Measurement precision
If temperature sensors are provided for each switching element to detect temperatures, then temperature monitoring capability is improved, but the complexity of failure detection increases
Solution Approach 1:
The patent segments the temperature monitoring system into paired sensor groups corresponding to adjacent switching elements. By dividing the full set of temperature sensors into specific pairs, the system simplifies failure detection to comparing only these paired differences, reducing computational complexity while maintaining comprehensive monitoring coverage.
Solution Approach 2:
Instead of determining failure by checking if individual sensor readings exceed absolute thresholds, the patent inverts the approach by determining failure through abnormal differences between paired sensors. This inversion transforms the problem from detecting absolute anomalies to detecting relative anomalies, which is more robust to environmental variations and simplifies the detection logic.
3Temperature
If a flow rate of cooling water drops at extremely low temperature, then a significant temperature difference arises temporarily in the PCU, but this causes erroneous detection of sensor failures
Solution Approach 1:
The patent introduces the temperature difference between adjacent sensors as an intermediary parameter to detect sensor failures. Rather than directly monitoring absolute temperatures or individual sensor readings, the system uses the differential temperature (ΔT) as a mediator that naturally compensates for ambient temperature variations and cooling flow rate changes, eliminating erroneous detections during low-temperature operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents erroneous detection of temperature sensor failures, reduces the number of incorrectly identified failed sensors, and minimizes motor output restrictions in low temperature environments, enhancing product quality by accurately identifying sensor failures.
Implementation Method 1
a plurality of temperature detection members at least one of which is provided for one of the plurality of switching elements to detect a temperature of each of the plurality of switching element
Implementation Method 2
a refrigerant flow passage in which a refrigerant for cooling the plurality of switching elements flows
Implementation Method 3
a refrigerant for cooling the plurality of switching elements flows
Data Source
AI summary
A power converter which can prevent an erroneous detection even when a flow rate of a refrigerant is low and a vehicle having the power converter mounted therein are provided. A first inverter circuit including: an element group constituted by six transistors; six diode temperature sensors at least one of which is provided for each transistor to detect a temperature of the transistor; and a high arm-side refrigerant flow passage and a low arm-side refrigerant flow passage in which a refrigerant for cooling the transistors flows is provided. In a failure detection device of the first inverter circuit, a failure determination member selects two diode temperature sensors among the plurality of diode temperature sensors, which detect temperatures of two adjacent transistors, as an adjacent sensor pair, and determines a failure of any one of the plurality of diode temperature sensors using detection values of the adjacent sensor pair.