Inductive Open-Circuit Sensing for Reliable Conductor State Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies struggle to accurately determine the open or closed state of a conductor in an electrical circuit without relying on current flow, which is necessary for safety compliance with standards like ISO 26262.
Innovation Solution
An inductive open-circuit sensor using inductive coupling, comprising a conductor with a relay, a transmitting coil, magnetoresistance circuitry, and a main signal path to detect the net magnetic field and determine the conduction state based on induced currents, employing feedback loops for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical position sensing is used to detect conductor state, then the detection method is simple, but it cannot reliably determine open/closed state without relying on current flow, failing safety compliance
Solution Approach 1:
The patent replaces mechanical position sensing with inductive coupling-based electromagnetic sensing. A transmitting coil generates a magnetic field that couples inductively with a receiving coil in the conductor, enabling detection without mechanical contact or current flow dependency. This substitution achieves ASIL compliance while maintaining detection reliability.
Solution Approach 2:
The patent introduces magnetic field coupling as an intermediary mechanism between the sensor and conductor. The transmitting coil generates a magnetic field that serves as an intermediary to induce current in the receiving coil, enabling indirect detection of conductor state without direct mechanical interaction or requiring current flow through the sensing path.
2Reliability
If inductive coupling is used to detect conductor state, then safety compliance is achieved, but the system becomes more complex with multiple coils and circuitry
Solution Approach 1:
The patent merges the transmitting coil and receiving coil into an integrated sensor package. The coils are positioned in close proximity within the same package, allowing magnetic field coupling while minimizing overall device footprint. This merging approach achieves safety compliance without proportionally increasing device complexity.
Solution Approach 2:
The inductive coupling sensor serves multiple functions: it detects open/closed conductor state, provides safety monitoring, and can operate without requiring current flow through the sensing path. The same coil structure enables both transmission and reception of magnetic fields, making the sensor multi-functional for safety compliance.
3Measurement precision
If current flow is required to determine conductor state, then the detection is straightforward, but it cannot provide reliable open/closed state information for safety purposes
Solution Approach 1:
The patent employs periodic alternating current drive signals in the transmitting coil to generate time-varying magnetic fields. This periodic action induces corresponding alternating currents in the receiving coil, enabling detection of conductor state through the presence or absence of induced current. The periodic drive allows reliable state detection without requiring continuous current flow through the conductor.
Solution Approach 2:
The patent substitutes current-flow-based detection with magnetic field-based inductive coupling. Instead of relying on current flow through the conductor to determine its state, the system uses magnetic field coupling between coils to detect whether the conductor is open or closed, providing both measurement precision and safety compliance.
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 reliable detection of conductor states without mechanical position sensing, ensuring compliance with safety standards by accurately distinguishing between open and closed circuits, enhancing system reliability and achieving Application Safety Integration Level (ASIL) as per ISO 26262.
Implementation Method 1
a first transmitting coil disposed on an IC die within the IC package and configured to produce a reference magnetic field at a reference frequency in response to receiving a drive current
Implementation Method 2
the reference magnetic field is configured to produce an induced current in the coil portion of the conductor when the relay is in a closed state
Implementation Method 3
magnetoresistance circuitry disposed within the IC package and configured to sense a net magnetic field as a combination of the reference magnetic field and an induced magnetic field generated by the induced current when present
Data Source
AI summary
Systems, circuits, and methods provide for detection of open-circuit states in an external conductor using inductive coupling. An on-chip coil is used to generate a reference magnetic field. An in-package conductor loop is connected to the external conductor. When the external conductor is continuous, the reference magnetic field generates an induced current in the in-package conductor whereas no induced current is generated when the external conductor is broken. The presence of an induced current produces an induced magnetic field, tending to cancel the reference magnetic field. The cancellation or attenuation of the reference magnetic field can be detected by an included magnetic field sensor and a comparator. Examples can include use of a closed loop acting as a feedback loop. The feedback loop can adjust the strength of a feedback magnetic field directed at the magnetic field sensor and used to compensate for nonlinearities of the magnetic field sensor.