Inductive Position Sensor Common Mode Correction
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Solution Overview
Problem
Conventional mechanically connected throttle control systems in motorized vehicles are being replaced by electronically controlled systems, which require reliable and cost-effective solutions for position sensing, especially in applications where mechanical calibration is challenging and prone to variations due to manufacturing tolerances and environmental factors.
Innovation Solution
A non-contacting inductive sensor system utilizing a transmitter coil, receiver coils, and a coupler element, where the coupler element modifies the inductive coupling between the coils to correlate the receiver signal with the position of a movable part, and a reference coil generates a signal independent of the coupler element's position to compensate for common mode factors, allowing for accurate and reliable position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-contacting inductive sensor system is used, then reliability and resistance to manufacturing variations are improved, but device complexity increases due to multiple coils and signal conditioning circuitry
Solution Approach 1:
The patent combines the transmitter coil, receiver coils, and reference coil into a single integrated coil assembly structure. This merging approach maintains the functional benefits of multiple coils for reliable position sensing while reducing overall device complexity through spatial and structural integration.
Solution Approach 2:
The coil assembly serves multiple functions simultaneously: the transmitter coil generates the electromagnetic field, the receiver coils detect position-dependent signals, and the reference coil provides compensation for common-mode variations. This multi-functionality reduces the need for separate dedicated components, thereby improving reliability without proportionally increasing complexity.
2Ease of manufacture
If mechanical calibration is used in electronically controlled throttle systems, then ease of manufacture is improved, but manufacturing precision deteriorates due to tolerances and environmental factors
Solution Approach 1:
The patent replaces mechanical calibration systems with a non-contacting inductive sensing system. The position sensor uses electromagnetic fields and a coupler element to determine throttle position without mechanical contact or calibration, thereby maintaining ease of manufacture while achieving high manufacturing precision independent of tolerances and environmental factors.
Solution Approach 2:
The reference coil automatically compensates for common-mode signal variations caused by manufacturing tolerances and environmental factors. This self-service mechanism eliminates the need for external calibration procedures while maintaining high manufacturing precision across production batches.
3Measurement precision
If multiple receiver coils are used to extend angular range, then measurement precision is improved, but device complexity increases due to additional coils and signal processing
Solution Approach 1:
Multiple receiver coils are integrated into a single coil assembly with shared magnetic coupling to the coupler element. This merging approach extends the measurable angular range through combined signal information while reducing device complexity by eliminating separate mounting structures and simplifying signal processing architecture.
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 system provides a reliable and cost-effective means of determining the position of movable parts, such as a throttle pedal, with improved resistance to manufacturing variations and environmental factors, enabling precise control of engine speed without the need for extensive calibration.
Implementation Method 1
a transmitter coil generating electromagnetic radiation when the transmitter coil is excited by a source of electrical energy
Implementation Method 2
the receiver coil generating a receiver signal when the transmitter coil is excited due to an inductive coupling between the receiver coil and the transmitter coil
Data Source
AI summary
An inductive position sensor for rotary motion includes a transmitter coil and a receiver coil, the receiver coil generating a receiver signal when the transmitter coil is excited by an alternating current source. A movable coupler element modifies the inductive coupling between the transmitter coil and the receiver coil so that the receiver signal is sensitive to the coupler element position. The ratio between the receiver signal and the reference signal is sensitive to the coupler element position, but substantially insensitive to common mode factors. The angular or positional range of the position sensor can be increased using a plurality of receiver coils.