Rotary Transformer Capacitive Coupling High Frequency Response
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Solution Overview
Problem
Existing rotary transformers experience degradation in magnetic coupling at high frequencies, limiting their bandwidth and causing signal amplitude roll-off, which restricts their ability to effectively couple electrical signals across rotating and non-rotating components in catheter systems.
Innovation Solution
A rotary transformer design featuring a rotary shaft with a first magnetic core and winding, and a hollow second magnetic core with a winding along its inner wall, utilizing capacitive coupling through closely spaced circular loops with jogs to maintain constant overlap and provide low impedance conduction at high frequencies, thereby extending the frequency response and preventing amplitude modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rotary transformers use magnetic coupling between windings, then signal coupling is achieved at low frequencies, but magnetic coupling degrades at high frequencies causing signal amplitude roll-off and limited bandwidth
Solution Approach 1:
The patent introduces capacitive coupling as an intermediary mechanism between the primary and secondary windings. The capacitive coupling formed by closely spaced circular loops acts as a mediator that enables high-frequency signal transmission when magnetic coupling degrades, thereby extending the frequency response and maintaining signal coupling reliability across a wider bandwidth range
Solution Approach 2:
The patent changes the coupling mechanism from purely magnetic to a hybrid magnetic-capacitive system. By introducing capacitive coupling through closely spaced loops and adjusting the gap distance, the system transitions to a parameter regime where capacitive effects dominate at high frequencies, preventing signal roll-off and extending bandwidth
2Manufacturing precision
If circular loops of windings are closely spaced to provide capacitive coupling, then bandwidth is extended and high-frequency response is improved, but maintaining constant overlap during rotation requires precise alignment
Solution Approach 1:
The patent uses asymmetric positioning of the circular loops with strategic gaps that compensate for rotational movement. The non-uniform gap distribution creates a configuration where the capacitive coupling remains substantially constant during rotation, eliminating the need for precise continuous alignment while maintaining extended bandwidth performance
Solution Approach 2:
The patent pre-configures the circular loops with specific gap positions before assembly. By preliminarily establishing the correct spatial relationship and overlap pattern during manufacturing, the system ensures constant capacitive coupling during operation without requiring complex real-time alignment mechanisms
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 design enhances the bandwidth of the rotary transformer by maintaining constant capacitive coupling during rotation, reducing signal distortion, and providing a low impedance path for high-frequency signal transmission, thus enabling wider bandwidth and more reliable signal coupling.
Implementation Method 1
The two cores provide magnetic coupling between the two windings, thereby coupling electrical signals from one winding to the other winding
Implementation Method 2
The first and second windings are closely spaced to provide capacitive coupling between the two windings. The capacitive coupling extends the frequency response of the rotary transformer by providing a low impedance conduction path between the two windings at high frequencies
Data Source
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AI summary
Described herein are rotary transformers for coupling signals between components that rotate relative to one another. In an exemplary embodiment, a rotary transformer (10) comprises a rotary shaft (15), a first magnetic core (20) on the rotary shaft, and a first winding (25) wound around the first magnetic core. The rotary transformer further comprises a hollow second magnetic core (30), and a second winding (35) wound along the inner wall of the second magnetic core. During operation, the first winding on the rotary shaft rotates within the second winding with the magnetic cores magnetically coupling signals between the two windings. Also, the first and second windings are closely spaced to provide capacitive coupling between the windings that extends the frequency response of the transformer. In one embodiment, the windings comprise substantially flat conductors wound in the shape of the windings. In another embodiment, each of the windings comprises circular loops connected by jogs.