Relay State Detection via Back-EMF Current Inflection
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Solution Overview
Problem
Off-the-shelf latching relay devices lack a feedback mechanism to indicate their operational state, making it costly and impractical to detect the state using position sensors like Hall effect sensors, especially when the movement between open and closed states is short.
Innovation Solution
A method and system that apply a voltage signal to a solenoid, monitor current flow, and calculate back-emf voltage to determine the operational state of a relay switch without using position sensors, by analyzing current vs. time data and waveform inflections to assess whether the relay has changed states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors like Hall effect sensors are used to detect relay state, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The relay device uses its own existing components (solenoid coil, plunger, contacts) to generate feedback signals for state detection. The system monitors current flow and voltage characteristics inherent to the relay's operation to determine its state, eliminating the need for external position sensors. This self-service approach resolves the contradiction by achieving accurate measurement without adding device complexity.
Solution Approach 2:
The patent replaces mechanical position sensors with an electrical field-based detection method. Instead of using physical sensors to detect plunger position, the system uses electrical characteristics (current, voltage, impedance changes) to infer the relay state. This substitution eliminates the need for additional mechanical or electromagnetic sensing components while maintaining detection accuracy.
2Reliability
If position sensors are installed to detect relay state, then reliability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The relay uses its own operational characteristics to provide state feedback. By monitoring parameters already present during normal operation (current through the solenoid, voltage across contacts), the system achieves reliable state detection without requiring additional sensors or modified manufacturing processes. This approach maintains ease of manufacture while ensuring reliable operation.
Solution Approach 2:
The system implements feedback by continuously monitoring electrical parameters and comparing them against expected values for different relay states. This feedback mechanism provides reliable state information without requiring physical sensors, thereby simplifying the manufacturing process while maintaining operational reliability.
3Measurement precision
If additional sensors are added to detect relay state, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The relay system continuously monitors its own electrical characteristics during normal operation, enabling real-time state detection without requiring separate measurement cycles or additional time. The state information is derived from parameters already being measured for other operational purposes, eliminating time loss associated with dedicated sensing operations.
Solution Approach 2:
The detection system operates continuously by monitoring electrical parameters throughout the relay's operation. Rather than requiring discrete measurement intervals or additional sensing steps, the system maintains continuous awareness of the relay state through ongoing electrical characteristic analysis, thereby eliminating time loss.
4Ease of manufacture
If off-the-shelf latching relay devices are used without feedback mechanisms, then ease of manufacture is improved, but loss of information increases
Solution Approach 1:
The patent implements feedback by extracting state information from the relay's own electrical characteristics. The system monitors current flow through the solenoid, voltage across contacts, and impedance changes to determine the relay state. This feedback mechanism provides complete operational state information while maintaining the simplicity of off-the-shelf relay devices, resolving the contradiction between ease of manufacture and information availability.
Solution Approach 2:
The system replaces physical feedback mechanisms (such as position sensors or mechanical indicators) with electrical field-based detection. By analyzing electrical characteristics inherent to the relay's operation, the system recovers operational state information without adding physical components, thereby maintaining manufacturing simplicity while eliminating information loss.
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
Enables the detection of relay states without additional sensors, reducing costs and process time, and accurately identifying state changes and potential faults in the relay device.
Implementation Method 1
an electromagnetic coil is energized or de-energized to move an actuator that opens or closes
Implementation Method 2
The application of voltage to the electromagnetic coil causes current flow which generates the magnetic field. Current flow in the electromagnetic coil (i.e. a solenoid) produces the magnetic field which pulls a contact from one state
Implementation Method 3
calculates a back-emf voltage impressed on the solenoid based on an inflection in the current occurring as a plunger of the relay switch moves
Data Source
AI summary
A method and system for monitoring a state of a relay switch. The method applies a voltage signal to a solenoid of the relay switch for actuation of the relay switch, monitors over time current flowing through the solenoid after application of the voltage signal, and calculates a back-emf voltage impressed on the solenoid based on an inflection in the current occurring as a plunger of the relay switch moves. The system includes a voltage source, at least one solenoid solenoid having a plunger, a switch connected to the plunger, and a controller configured to data log the voltage applied to the solenoid and the current flowing through the solenoid upon application of the voltage.