Resonant Inductive Coupler for Rotary Steerable Drilling Power Transfer
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Solution Overview
Problem
Conventional inductive couplers face inefficiencies in power transfer due to magnetic flux leakage when coils are separated or have air gaps, leading to weak coupling and low power efficiency between the primary and secondary coils.
Innovation Solution
The system employs resonantly tuned circuits with impedance matching techniques, where both coils are resonated at the same frequency, and high-quality factors are maintained to compensate for flux leakage, allowing efficient power transfer between the transmitter and receiver coils, even with loose coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional inductive couplers use separated coils with air gaps, then device complexity is reduced, but power transfer efficiency deteriorates due to magnetic flux leakage
Solution Approach 1:
The patent applies parameter changes by resonating both primary and secondary coils at the same frequency, which fundamentally changes the operating parameters of the inductive coupling system. This resonance condition creates strong coupling between the coils, compensating for the air gaps and physical separation, thereby maintaining high power transfer efficiency while allowing for simpler, separated coil structures.
Solution Approach 2:
The patent utilizes electromagnetic oscillation (analogous to mechanical vibration) by tuning both coils to resonate at the same frequency. This resonant oscillation creates a strong coupling effect that overcomes the detrimental effects of air gaps and physical separation, enabling efficient power transfer without requiring complex magnetic shielding or closely coupled coil structures.
2Reliability
If coils are physically separated to avoid wet environment short circuits, then reliability in wet environments is improved, but magnetic flux leakage increases reducing power efficiency
Solution Approach 1:
The patent changes the operating parameters by implementing resonant frequency tuning on both primary and secondary coils. This parameter change creates a strongly coupled resonant system that maintains high power transfer efficiency even when coils are physically separated to avoid wet environment contact, thus resolving the contradiction between reliability in wet environments and power transfer efficiency.
3Loss of energy
If impedance matching and resonant tuning are implemented, then power transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements parameter changes through impedance matching and resonant frequency tuning of the coils. While this does increase circuit complexity, it achieves the primary goal of high power transfer efficiency (>99%) even with loose coupling. The complexity is concentrated in the tuning and matching circuits, which enable the system to operate efficiently under various conditions.
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
This approach achieves high power efficiency, with efficiencies greater than 99% even with axial and transverse displacements, and is robust against frequency drifts and component variations, enabling reliable power transmission in challenging environments like drilling operations.
Implementation Method 1
the transmitter coil and the receiver coil are positioned with respect to one another such that power is coupled from the power transmitting coil to the power receiving coil
Implementation Method 2
both coils are resonated at the same frequency, and high-quality factors are maintained to compensate for flux leakage
Data Source
AI summary
A motor steering system includes a drill collar, a transmitter circuit having a power transmitting coil, a rotor, and a receiver circuit having a power receiving coil. The transmitter circuit is coupled to the drill collar and the receiver circuit is coupled to the rotor such that the transmitter circuit and the receiver circuit are positioned with respect to one another such that power is coupled from the power transmitting coil to the power receiving coil whereby the drill collar provides electric power to the rotor.