Parallel Switch Failure Detection Using Series Temperature Sensors
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Solution Overview
Problem
In circuits with parallel-driven switches, abnormal overheating occurs due to open failures, potentially damaging switches and surrounding components, as current concentrates on normally closed switches, necessitating effective failure detection to prevent damage.
Innovation Solution
A failure detection device using at least two temperature sensors with changing resistance values, connected in series, to detect combined resistance changes and determine switch failures, integrated into a motor drive device with a converter circuit, DC link capacitor, and pre-charging circuit to prevent inrush currents and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switches are connected in parallel to handle high current, then the current handling capability is improved, but the risk of abnormal overheating due to open failure increases
Solution Approach 1:
The patent applies preliminary action by detecting switch failures before they cause abnormal overheating. Temperature sensors continuously monitor the switches, and the detection circuit identifies open failures early, allowing the system to take preventive measures before harmful overheating occurs.
Solution Approach 2:
The patent implements feedback through a closed-loop detection system. Temperature sensors monitor the thermal state of parallel switches, the detection circuit processes this information, and the system responds by identifying failures and can trigger protective actions, creating a continuous feedback loop that prevents harmful overheating.
2Measurement precision
If temperature sensors are connected in series to detect combined resistance changes, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies merging by connecting multiple temperature sensors in series to form a combined detection circuit. This configuration allows the system to detect the sum of resistance changes from all sensors, improving failure detection accuracy while using a unified circuit approach rather than multiple independent detection paths.
Solution Approach 2:
The patent implements universality by designing the temperature sensor circuit to serve multiple functions: individual sensor monitoring, combined resistance detection for failure identification, and thermal state monitoring. This multi-functional design improves detection capability without proportionally increasing circuit complexity.
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
The solution effectively detects switch failures, preventing abnormal overheating and potential damage by accurately determining combined resistance changes, allowing for timely intervention and maintaining circuit integrity.
Implementation Method 1
at least two temperature sensors having resistance values between terminals that change in response to a change in temperature
Data Source
AI summary
The failure detection device detects failure in switches that are selectively switched between conduction and non-conduction in a current path, and includes: two or more temperature sensors in which a resistance value between terminals changes in accordance with temperature changes, the two or more temperatures sensors being provided near two or more of the switches connected to each other in parallel, and the two or more temperatures sensors being electrically connected in series to each other; a detection unit that detects the combined resistance value of the two or more temperature sensors; and a determination unit that determines, based on a combined resistance value, that one or more of the two or more switches has failed.