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Rotary transformer

A rotary transformer is a specialized electrical device that transfers electrical power or signals between two components rotating relative to each other, utilizing magnetic coupling across an air gap to enable contactless operation similar to a conventional transformer but adapted for rotational motion.^[1]^[2] Unlike traditional slip ring systems, rotary transformers eliminate physical contacts such as brushes, thereby reducing wear, maintenance needs, frictional losses, and contamination risks while providing high reliability in dynamic environments.^[1]^[2]^[3] Their working principle relies on electromagnetic induction between primary and secondary windings separated by a mechanical or magnetic air gap, often operating at high frequencies with power electronics to maintain efficient energy transfer without motion-induced back electromotive force (EMF).^[1]^[3] Common designs include cylindrical coaxial topologies with ferrite cores for large shafts and axial or pot-core configurations for compact applications, which accommodate through-bores and minimize changes in electrical characteristics during rotation.^[1]^[2] Rotary transformers find essential use in demanding sectors requiring robust, wireless power delivery, such as in spacecraft antennas and instruments (as demonstrated by signal transfer in the Galileo mission, 1989–2003), solar arrays, helicopter de-icing systems, as well as robotics, electric vehicle traction motors, automotive, railway, naval, and industrial machinery.^[2]^[3]^[1] Recent examples include high-speed designs for electric motors exceeding 20,000 rpm with 92–95% efficiency (as of 2025).^[4] They support high power densities, with prototypes achieving up to 10.7 kW at 95.9% efficiency and power factors around 0.91, often enhanced by resonant compensation techniques to handle variations in load or resistance.^[3] Key advantages include suitability for high-speed rotations, long operational life without mechanical degradation, and compact, lightweight constructions using materials like sliced C-shaped ferrite cores, making them preferable over slip rings in precision and space-constrained scenarios.^[1]^[3]^[2]

Overview

Definition and Purpose

A rotary transformer is an electromagnetic device that couples alternating current (AC) electrical signals or power between stationary and rotating components without physical electrical contacts, relying on mutual inductance for energy transfer.^[3] This contactless mechanism ensures that relative rotation between the windings does not significantly disrupt the magnetic coupling, avoiding motion-induced back electromotive forces.^[3] The primary purpose of a rotary transformer is to enable reliable, maintenance-free transfer of electrical energy across rotary interfaces in demanding environments, where traditional mechanical connections like slip rings and brushes would experience excessive wear, generate noise, or fail due to contamination and high-speed operation.^[2] By eliminating sliding contacts, it supports long-term reliability in applications involving continuous rotation or harsh conditions, such as those in industrial machinery or aerospace systems. At its core, a rotary transformer consists of a stationary primary winding and a rotating secondary winding (or vice versa), positioned coaxially and separated by a small air gap to facilitate magnetic flux linkage while accommodating rotation.^[3] These windings are typically mounted on ferromagnetic cores to enhance efficiency. It operates at frequencies ranging from 400 Hz to several kHz.^[5]^[6]

Historical Development

The rotary transformer, initially developed as a selsyn device around 1925, enabled the electrical transmission of angular position and rotation without mechanical linkages, marking an early milestone in contactless signal coupling for rotating systems.^[7] This innovation facilitated precise synchronization between a generator and receiver, replicating motion over distances via wired connections, and found initial applications in industrial control, including the Panama Canal's lock gate and valve stem positioning systems in the early 1900s.^[8] By the 1930s, refinements supported emerging needs in naval and aviation instrumentation, where reliable position sensing was critical for dynamic environments. During World War II, rotary transformers evolved into synchro systems—adopting the term "synchro" around 1942–1943—and saw widespread military adoption for fire-control mechanisms, transmitting angular data from gun sights to analog computers and relaying positioning commands to turrets on warships.^[8]^[7] The first commercial variants emerged in the 1940s for analog computing and precise position sensing in naval gunnery and aircraft control surfaces, replacing cumbersome mechanical linkages with electromagnetic coupling.^[8] Post-war, in the 1950s, these devices gained broad use in radar and servo systems, driving antenna positioning and heavy-load mechanisms like missile launchers with high accuracy.^[9] The 1960s brought integration into resolver configurations for aerospace applications, enhancing feedback in autopilots and control systems amid the era's rapid advancements in aviation and space exploration.^[10] Standardization efforts included military specifications, such as MIL-S-20708, which defined performance for synchros in defense systems and influenced subsequent commercial designs.^[11] In the modern era, from the 2000s onward, designs shifted toward fully non-contact variants to meet demands for maintenance-free operation in sensitive environments, including medical imaging devices like CT scanners where non-contact systems supplanted slip rings for power and data transfer in rotating gantries.^[12] Post-2010 developments have focused on high-speed, efficient models for renewable energy and electrification, such as wound-rotor excitation in electric vehicle motors and wind turbine generators, addressing efficiency and reliability in high-power rotating applications.^[13]

Operating Principle

Electromagnetic Coupling

In a rotary transformer, electromagnetic coupling facilitates the contactless transfer of electrical signals or power between stationary and rotating components through magnetic flux linkage. The primary winding, affixed to the stationary part, is excited by an alternating current, producing a time-varying magnetic field that permeates the surrounding magnetic core. This field threads through the secondary winding on the rotating part, inducing a voltage without direct electrical connections, in accordance with Faraday's law of electromagnetic induction.^[14] The core of this coupling lies in the mutual inductance M between the windings, which quantifies the flux linkage. The induced electromotive force (EMF) in the secondary winding arises from the changing primary current and is expressed as

\mathcal{E}_s = -M \frac{dI_p}{dt},

where I_p is the primary current. For sinusoidal operation at angular frequency \omega, the phasor form simplifies to

V_s = j \omega M I_p,

enabling voltage transformation proportional to \omega and M. This mechanism supports power transfer across the interface, with the coupling coefficient k = M / \sqrt{L_p L_s} (with L_p and L_s as self-inductances).^[15] Rotation is accommodated by designs such as cylindrical or disk geometries, which preserve a uniform air gap—typically 0.25 to 0.6 mm—between the cores to sustain consistent magnetic reluctance despite relative motion.^[14] The air gap introduces higher reluctance than the core material, concentrating flux density (e.g., reducing from ~0.2 T in the core to 0.1–0.2 T in the gap), but its minimal size ensures effective linkage without mechanical interference.^[14]^[15] To mitigate angular misalignment and associated torque ripple from uneven flux distribution, multi-pole windings are employed, creating a more uniform magnetic field that minimizes variations in mutual inductance during operation. This approach reduces magnetic forces that could otherwise induce rotational drag or instability.^[14]

Performance Factors

Rotary transformers operate most effectively within a frequency range of 2 to 10 kHz, which optimizes electromagnetic coupling while minimizing losses such as eddy currents in the core. At frequencies below this range, larger core sizes or higher magnetizing currents may be needed, potentially increasing losses. Conversely, frequencies above 10 kHz can exacerbate capacitive effects, leading to unwanted parasitic currents and reduced power transfer quality.^[16]^[17] Speed capabilities in rotary transformers vary by design but can reach 10,000 to 30,000 RPM in high-performance configurations, constrained primarily by centrifugal forces on windings and potential mechanical resonance. The rotational speed influences the slip frequency, calculated as f_{\text{slip}} = \frac{\text{RPM}}{60} \times \text{number of pole pairs}, which represents the electrical frequency shift due to relative motion in multi-pole systems.^[17] Efficiency in rotary transformers typically ranges from 85% to 97%, heavily influenced by load matching between primary and secondary circuits to minimize reflections and resistive losses. Power handling capacity spans from milliwatts in precision signal applications, such as resolvers, to several kilowatts in high-power transfer scenarios, enabling diverse uses from instrumentation to motor excitation.^[18] These devices exhibit robust environmental tolerances, operating reliably from -55°C to +155°C and enduring vibrations up to 20g across 10–500 Hz, attributes critical for aerospace and defense deployments where thermal extremes and mechanical stresses are prevalent.^[17] The efficiency \eta of a rotary transformer, defined as the ratio of output power to input power, can be modeled for resonant coupled systems as

\eta = \frac{P_{\text{out}}}{P_{\text{in}}} = \frac{k^2 Q_1 Q_2}{1 + k^2 Q_1 Q_2},

where k is the magnetic coupling coefficient between coils, and Q_1 and Q_2 are the quality factors of the primary and secondary circuits, respectively. This expression derives from the maximum power transfer theorem in inductively coupled resonators, assuming critical coupling and negligible parasitic losses; it highlights how strong coupling (k \approx 1) and high quality factors enhance overall performance.^[19]

Design and Construction

Core and Winding Configurations

Rotary transformers employ various core and winding configurations to accommodate different operational requirements, such as speed, power handling, and space constraints. The primary configurations include axial, radial, and hybrid designs. Axial configurations, often disk-like for low-profile applications, position the primary and secondary windings face-to-face across an air gap along the rotation axis, making them suitable for high-speed operations where axial space is limited.^[2]^[14] Radial configurations adopt a cylindrical structure with concentric windings, ideal for high-torque and power transmission scenarios due to their ability to handle larger flux paths radially. Hybrid designs combine elements of both, such as pot-core arrangements that integrate axial flux paths with radial elements for balanced performance in compact systems.^[2] Winding types are selected to optimize electrical performance under rotation. Litz wire, consisting of multiple insulated strands, is commonly used for high-frequency applications to mitigate skin effect and reduce AC resistance losses.^[14] Multi-layer windings enhance flux distribution and coupling efficiency by layering turns on bobbins, though they must be carefully designed to avoid proximity effect issues in pot-core setups.^[20] Core structures play a critical role in minimizing magnetic losses while supporting mechanical integrity. Ferrite cores, such as MN60 grade, are favored for their low losses and high permeability at frequencies up to several kilohertz, enabling efficient power transfer in axial designs.^[14] Laminated silicon steel cores provide robustness and higher saturation flux density for lower-frequency, high-power radial applications, though they introduce more eddy current losses at elevated speeds. Air-core configurations, relying primarily on the air gap for flux linkage, are employed in ultra-high-speed variants to eliminate core saturation limits, albeit at the cost of reduced coupling efficiency.^[2] The air gap between rotating and stationary components is optimized to balance electromagnetic coupling with mechanical stability, typically sized at 1-5% of the core diameter—such as 0.5-2 mm for cores around 50-100 mm in diameter—to minimize magnetizing current while accommodating tolerances.^[14]^[21]^[20] Alignment features ensure concentric rotation; conventional designs incorporate ball bearings to maintain gap precision, while advanced systems may use magnetic levitation for frictionless operation at extreme speeds, though this remains less common due to complexity. These configurations directly influence overall efficiency, with optimized gaps and windings achieving up to 99% in high-power setups.^[14]

Materials and Manufacturing

The core of a rotary transformer is typically constructed from high-permeability materials to minimize magnetic losses and ensure efficient coupling across the rotating interface. For high-frequency applications, such as those exceeding 1 MHz, nickel-zinc (NiZn) ferrites are commonly selected due to their low eddy current losses and high resistivity, enabling compact designs with reduced core heating.^[22] In lower-frequency or higher-power scenarios, non-grain-oriented silicon steel, such as M400-50A grade, is preferred for its saturation flux density of up to 1.5 T, which supports higher magnetic flux handling without saturation.^[23] Amorphous metals are also employed in some designs to achieve low core losses—approximately one-tenth those of conventional silicon steel—through their non-crystalline structure, which reduces hysteresis and eddy currents, particularly beneficial for continuous rotation.^[24] Windings in rotary transformers are generally made from copper conductors to optimize electrical conductivity and minimize resistive losses, with enameled or insulated configurations ensuring reliable operation under rotational stress. For elevated temperature environments, up to 400°C, silver-plated copper wire insulated with polyimide film is utilized, providing excellent thermal stability, abrasion resistance, and dielectric strength.^[25] These materials allow windings to withstand the mechanical demands of rotation while maintaining low leakage inductance. Manufacturing processes emphasize precision to achieve tight tolerances in the air gap and alignment, critical for performance. Computer numerical control (CNC) winding machines are standard for layering coils uniformly on the core, followed by vacuum impregnation with epoxy resin to enhance insulation integrity and eliminate voids, as seen in resin-baked assembly methods for laminated cores.^[23] Recent advancements since 2015 include 3D printing for prototyping components like carbon-fiber-reinforced polyether ether ketone (CF-PEEK) housings, which offer lightweight, corrosion-resistant alternatives for testing in harsh conditions.^[26] To protect against environmental factors in demanding applications, rotary transformers often feature hermetic encapsulation, achieving IP67 ratings for dust and water immersion resistance through epoxy or silica potting of the core and windings.^[27] A primary challenge in fabrication is balancing low weight—typically under 500 g for aerospace units—with high power density, up to 1 kW/kg, requiring optimized coreless or lightweight ferrite designs to minimize rotational inertia while delivering outputs like 200 W at 60,000 rpm.^[28]

Types and Variants

Resolver-Type Rotary Transformers

Resolver-type rotary transformers, commonly known as resolvers, are electromechanical devices that serve as analog position sensors by converting the angular position of a rotating shaft into electrical signals through electromagnetic coupling. They consist of a rotor with a primary winding and a stator featuring two secondary windings oriented 90 degrees apart, producing outputs modulated by sine and cosine functions of the shaft angle θ. This configuration enables precise measurement of angular displacement without physical contact, making resolvers a robust variant of rotary transformers for applications requiring reliable feedback.^[29]^[30] In operation, the rotor's primary winding is excited by an alternating current signal, typically at frequencies of 1 to 10 kHz, which induces voltages in the stator's secondary windings via the rotary transformer's coupling. The resulting stator outputs are amplitude-modulated signals whose envelopes vary as the sine and cosine of the rotor angle θ, providing continuous analog representation of position. These signals are processed by a resolver-to-digital converter to determine the exact shaft angle, often used for commutation in brushless motors where precise rotor position feedback is essential.^[31]^[32]^[33] The output voltages follow the equations:

V_{\sin} = K \sin(\theta)

V_{\cos} = K \cos(\theta)

where K is a constant proportional to the excitation voltage amplitude. The angular position θ is then calculated using the arctangent function:

\theta = \tan^{-1}\left(\frac{V_{\sin}}{V_{\cos}}\right)

This derivation leverages the trigonometric identity \tan(\theta) = \sin(\theta)/\cos(\theta), ensuring unambiguous position determination over a full 360° range by considering the quadrant based on the signs of V_{\sin} and V_{\cos}.^[29]^[34] Resolvers achieve high accuracy, with accuracies as fine as 1 arc-minute, allowing for precise angular measurements in demanding environments. Their design supports absolute positioning over 360 degrees without the need for batteries or external power for memory, distinguishing them from incremental encoders that require homing or power to retain position data.^[35]^[34]

Rotary Variable Differential Transformers (RVDTs)

A rotary variable differential transformer (RVDT) is a specialized variant of the rotary transformer that employs a differential configuration with a single primary winding and two secondary windings, typically arranged to produce an AC output signal linearly proportional to small angular displacements of the rotor.^[36] This setup allows for precise measurement of angular deviation, where the rotor's rotation modulates the magnetic coupling between the primary and secondaries, unbalancing their induced voltages.^[37] Unlike full-rotation resolvers, RVDTs are optimized for limited angular ranges, providing high-resolution feedback in position-sensing applications.^[38] In operation, an AC excitation voltage applied to the primary winding induces voltages in the two secondary windings, which are connected in series opposition. Rotor movement causes unequal coupling, resulting in a differential output voltage that varies with the angular position θ. For small displacements, this produces a change in output ΔV ≈ G θ (in radians), where G is the sensitivity, often reaching up to 5 V/rad depending on the design and excitation level.^[39] The full differential output is given by the ratiometric equation:

V_\text{out} = V_p \frac{k_2 - k_1}{k_1 + k_2}

where V_p is the primary excitation voltage and k_1, k_2 are the coupling coefficients of the secondary windings, which vary with rotor angle; this form ensures amplitude modulation independence when processed ratiometrically.^[38] RVDTs typically offer linear operation over angular ranges of ±30° to ±80°, with nonlinearity errors less than 0.5% of full scale within the specified band, enabling accurate sensing in constrained motion scenarios.^[40] A key advantage is the use of phase-sensitive detection, which demodulates the output to provide bidirectional angular information—the phase relative to the excitation indicates displacement direction—while remaining immune to variations in excitation amplitude up to 7.5%.^[36] This feature enhances reliability in dynamic environments requiring precise, direction-aware feedback.

Applications

Aerospace and Defense

Rotary transformers play a critical role in radar systems, particularly for enabling continuous antenna rotation in beam steering applications. They facilitate contactless transfer of power and high-frequency signals from stationary components to the rotating antenna platform, preventing wear from mechanical contacts like slip rings. This design ensures reliable operation in environments demanding uninterrupted signal transmission during high-speed rotations.^[41] In avionics, rotary transformers, often integrated as resolvers, provide essential position feedback for flight control surfaces and gyroscopic instruments. These devices convert angular shaft positions into electrical signals, supporting precise servo mechanisms in aircraft stabilization and navigation systems. For instance, brushless resolvers with rotary transformer coupling are employed in aerospace-grade actuators to deliver accurate, low-noise feedback under varying dynamic loads.^[42] Missile guidance systems utilize compact rotary resolvers for fin actuation, where they measure and control control surface positions to maintain trajectory accuracy. These resolvers, functioning as rotary transformers, endure extreme conditions, including shock levels up to 50g for 11 ms, ensuring functionality during launch and flight stresses. Their brushless construction enhances reliability in high-vibration scenarios typical of guided munitions.^[43]^[44]^[45] In defense platforms, rotary transformers integrate with MIL-STD-1553 data buses to support communication in rotating turrets and stabilized gimbals. They supply excitation to resolvers via constant-ratio transformation, enabling real-time position data transmission across the multiplexed network while accommodating mechanical rotation without signal interruption. This configuration is vital for fire control and targeting systems in armored vehicles and weapon stations.^[46] Rotary transformers have seen increased adoption in unmanned aerial vehicle (UAV) gimbals for intelligence, surveillance, and reconnaissance (ISR) missions, leveraging resolver-type variants for precise payload stabilization. These applications emerged prominently in the early 21st century, aligning with the growth of compact, high-endurance drone platforms requiring contactless rotary signal handling.^[47] Rotary transformers are utilized in spacecraft for contactless power and signal transfer to solar arrays and antennas, notably in the Galileo mission (1989–2003), where they replaced slip rings for high data rates and reliability over 14 years. They also enable power delivery in helicopter de-icing systems, such as for tail-rotors, handling approximately 4 kW in rotating environments.^[2]^[1]

Medical and Industrial Uses

In computed tomography (CT) scanners, rotary transformers enable contactless power transfer to the rotating gantry, supplying the X-ray tube without the need for slip rings or brushes. This design supports gantry rotations typically ranging from 0.3 to 1 second per revolution, facilitating high-speed imaging while delivering up to 100 kW of power to the X-ray source.^[48]^[49]^[50] The non-contact nature of rotary transformers in CT systems minimizes wear and particulate generation, leading to reduced maintenance requirements compared to traditional brush-based slip rings. By eliminating mechanical contacts, these devices lower overall operational costs and improve system reliability in high-precision medical environments.^[48] Industrial applications of rotary transformers include joint angle sensing in robotic arms, where resolver-type variants provide accurate position feedback for torque control and motion precision. Such resolvers, functioning as rotary transformers, have been integrated into automotive assembly lines since the 1990s to support automated manufacturing processes requiring robust, contactless sensing. They are also used in electric vehicle traction motors, such as for brushless doubly-fed induction generators in hybrid systems, and in automotive, railway, and naval applications for reliable power transfer across rotating interfaces in harsh conditions.^[10]^[3]^[1] In wind turbines, inductive rotary transformers facilitate power transfer for yaw control mechanisms, enabling nacelle positioning adjustments at low speeds up to 20 RPM even in harsh environmental conditions.^[51]

Advantages and Limitations

Key Benefits

Rotary transformers offer contactless operation through electromagnetic coupling, eliminating mechanical wear, sparking, and the maintenance requirements inherent in slip ring systems. This design extends operational lifespan significantly, often exceeding 100,000 hours without degradation from friction, in contrast to slip rings limited to approximately 80 million revolutions under typical conditions.^[52]^[53] The absence of physical contacts also prevents debris generation and electrical arcing, enhancing suitability for continuous rotation in demanding settings. Their reliability is a key advantage, making them ideal for vacuum or explosive environments where traditional brushed systems risk failure from sparking.^[54] Additionally, rotary transformers support high-bandwidth signal transfer up to 80 MHz with minimal noise, enabling efficient data transmission in precision applications.^[55] By avoiding brush-induced electromagnetic interference (EMI), rotary transformers deliver cleaner signals essential for sensitive electronics, reducing noise that could otherwise compromise system performance.^[56] In high-speed applications such as turbines, this translates to substantial cost savings via lower downtime; for instance, the elimination of mechanical contacts minimizes maintenance interruptions and extends service intervals.^[57] Such benefits are evident in medical imaging like CT scanners, where uninterrupted rotation demands high reliability.

Challenges and Drawbacks

Rotary transformers face significant power limitations, typically handling less than 10 kW effectively due to the challenges posed by the air gap, which increases magnetic reluctance and results in low magnetizing inductance and high leakage inductance. This leads to elevated magnetizing currents and substantial heating in the core and windings, necessitating careful thermal management to avoid efficiency drops and material degradation. For instance, prototypes often operate at 1-6 kW levels, with efficiencies around 90-96% under nominal conditions, but performance degrades at higher powers without enhanced cooling; however, recent designs as of 2022 have demonstrated up to 40 kW capabilities.^[58]^[59]^[21]^[60] These devices are inherently inefficient for direct current (DC) power transfer or very low frequencies, as the transformer operates on alternating magnetic fields; DC requires additional inversion to AC, introducing conversion losses and complexity, while low frequencies (e.g., below 5 Hz in rotor-tied applications) demand larger structures to compensate for reduced flux linkage, exacerbating size and loss issues.^[61]^[59] In terms of size and weight, rotary transformers are bulkier than slip rings for high-power scenarios, owing to the need for substantial magnetic cores and windings to bridge the air gap, which adds rotational inertia detrimental to precision applications like high-speed servos or sensors. This bulkiness stems from inefficient core utilization and the geometric constraints of the rotating interface, making them less suitable for compact, low-inertia designs.^[59]^[57]^[2] Cost is a notable drawback, with rotary transformers often more expensive upfront than slip rings due to the need for custom windings, specialized materials, and precise manufacturing processes. Assembly demands high alignment sensitivity to maintain consistent air gap uniformity (around 0.3-1 mm), as even minor misalignments increase leakage inductance and reduce coupling efficiency.^[57]^[2] Unshielded rotary transformers are susceptible to external magnetic fields, which can induce interference currents, distort flux paths, and degrade signal-to-noise ratios, particularly in sensitive environments like aerospace instrumentation.^[62] A key operational challenge arises at high speeds exceeding 30,000 RPM, where eddy current and hysteresis losses intensify due to elevated frequencies and mechanical stresses, often requiring active cooling to dissipate the resulting heat and prevent thermal runaway. Prototypes tested at 60,000 RPM show losses around 2 W, but scaling to higher powers amplifies these issues, limiting viability without advanced thermal solutions.^[61]^[28]

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[46]
[PDF] Chapter 1: Synchros and Resolvers - Analog Devices
This application of a Computing Resolver is often to be found in guidance systems such as those used in missiles and aircraft, ... rotating transformer as in the ...
[47]
https://www.analog.com/media/en/training-seminars/design-handbooks/synchro-resolver-conversion/Chapter1.pdf
[48]
Introduction to Cardiac Computed Tomography - Thoracic Key
Jul 10, 2016 · Typically the speed of this rotation ranges from 0.2 to 0.35 s/rev in most modern scanners and is the most important determinant of true ...
[49]
Computed Tomography - Radiology Key
Feb 12, 2017 · –Power loading on CT x-ray tubes can be as high as ~100 kW. –A tube voltage of 120 kV and tube current of 830 mA corresponds to 100 kW.
[50]
US10763670B2 - Rotating transformer and inductive coupling
Aspects of the present disclosure are generally directed to using a rotary transformer to transfer power for a wind turbine generator.
[51]
SDM New Energy Electric Vehicle Rotary Transformer
Apr 17, 2025 · ... Rotary Transformer ... After undergoing rigorous testing, the product has a lifespan of over 100,000 hours, with stable and reliable quality .
[52]
How long do slip rings last? - Knowledge - ByTune
Mar 2, 2023 · Well-maintained slip rings can last many years, even decades, but extreme conditions can shorten lifespan. Standard time is 80,000,000 rounds, ...
[53]
[PDF] The MAMMOTH Project - MSST
One of the very innovative features of the MAMMOTH scanner is the rotary transformer. ... It will initially have reliability of at least 200,000 hour MTBF ...
[54]
https://msstconference.org/MSST-history/1995/papers/B1_3.PDF
[55]
[PDF] Mitigating the Effects of Rotary Transformer Leakage Flux on ...
The primary drawbacks of brushed synchros include voltage drop across the brushes, noise interference, reduced accuracy, and the need for frequent maintenance.
[56]
[PDF] Optimal Design Methodology of a Three Phase Rotary Transformer ...
One such solution is to make use of a rotary transformer (RT) to replace the slip rings and brushes. The RT is placed on the same shaft as the generator and ...
[57]
[PDF] Kilowatt Three-phase Rotary Transformer Design for a Permanent ...
The aim of this thesis is to design a kilowatt three-phase step-down rotary transformer for a permanent magnet DC motor. The permanent magnet DC motor has ...
[58]
[PDF] Design and Evaluation of a Laminated Three-Phase Rotary ...
Jun 1, 2022 · Kilowatt Three-Phase Rotary Transformer Design for Permanent Magnet DC Motor with On-Rotor Drive System. Master's. Thesie, Mid Sweden ...
[59]
[PDF] Rotary Transformer Design for Brushless Electrically Excited ... - CORE
system with a rotary transformer, in order to excite the rotor of the same EESM. A rotary transformer is a transformer with an axial symmetry and an air gap ...
[60]
Study of Magnetic Interference on an LVDT: FEM Modeling and ...
May 23, 2011 · Static or slowly varying magnetic fields can affect the performances of linear variable differential transformer by inducing a position ...Missing: rotary susceptibility