Transformer-Based Circuit State Sensing With Galvanic Isolation
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Solution Overview
Problem
Existing circuit state sensing technologies face challenges in reliably detecting the state of safety-critical equipment, such as aircraft door switches, due to potential current/voltage leakage, electromagnetic interference (EMI), and the need for easy implementation across various applications, while avoiding high voltage sensing.
Innovation Solution
A circuit state sensing device utilizing a transformer with a primary and secondary coil, a measuring arrangement to assess impedance, and a processing arrangement to determine the circuit state, providing galvanic isolation and immunity to EMI, and capable of scalable configurations for multiple inputs with low component overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is implemented to prevent current/voltage leakage and EMI, then safety and reliability are improved, but device complexity increases due to the need for transformers and isolation components
Solution Approach 1:
The transformer serves multiple functions simultaneously: it provides galvanic isolation between circuits, enables impedance sensing through reflected impedance measurement, and blocks EMI. This multi-functionality reduces the need for separate isolation components, thereby improving safety while limiting complexity increase.
Solution Approach 2:
The patent replaces direct electrical connection (mechanical/electrical contact) with magnetic coupling through the transformer. This substitution achieves isolation without physical contact, preventing leakage and EMI while maintaining sensing capability through non-contact energy transfer.
2Measurement precision
If high voltage sensing is used to detect circuit states, then measurement precision is improved, but safety risks increase due to potential damage and inadvertent circuit activation
Solution Approach 1:
The transformer acts as an intermediary between the high voltage target circuit and the low voltage measuring circuit. It transfers energy and information from the high voltage side to the low voltage side through magnetic coupling, enabling precise measurement without direct high voltage exposure, thus maintaining measurement precision while eliminating safety risks.
Solution Approach 2:
The transformer creates an electrical copy or replica of the target circuit's electrical state on the primary side. This copy contains the same information (impedance, voltage state) but at safe voltage levels, allowing measurement without exposing the measuring circuit to harmful high voltages.
3Object-affected harmful factors
If a transformer-based sensing device is implemented to provide isolation, then immunity to EMI is improved, but the component count increases for each interface
Solution Approach 1:
The transformer provides multiple protective functions in a single component: EMI shielding through magnetic coupling, galvanic isolation to prevent leakage, and impedance transformation for sensing. This consolidation achieves EMI immunity without proportionally increasing component count, as the transformer replaces what would otherwise require multiple separate isolation and sensing components.
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 enables reliable detection of switch states and voltage conditions with complete isolation, immunity to EMI, and scalability, ensuring safe and efficient operation in diverse applications.
Implementation Method 1
a transformer having a primary coil and a secondary coil
Implementation Method 2
a measuring arrangement configured to take a measurement relating to impedance at the primary coil
Data Source
AI summary
A circuit state sensing device (100) includes a transformer (102) having a primary coil (104A) and a secondary coil (104B). In use, the secondary coil is connected to a target circuit (106) for which a state is to be sensed. The device further includes a measuring arrangement (112, 122) configured to take a measurement relating to impedance at the primary coil, and a processing arrangement (122) configured to process the impedance measurement to determine a state of the target circuit.