Bearing-Integrated Inductive Transformer for Rotor Power Transfer

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Solution Overview

Problem

Existing contact-based transformers for externally excited synchronous machines in electric vehicles suffer from mechanical and electrical losses, wear, contamination, and require significant installation space, limiting their power density, efficiency, and reliability.

Innovation Solution

A contactless energy transmission device is integrated with a ferrite core and windings arranged coaxially around a roller bearing, featuring a compact design with a radial air gap and modular units for primary and secondary coils, including inverter and rectifier electronics, to enhance thermal management and operational reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a contact-based transformer is used for energy transmission to the rotor, then mechanical and electrical connections are established, but mechanical and electrical losses occur, wear develops, and contamination increases

Engineering Contradiction:

Improveoperational reliabilityVSAvoidmechanical and electrical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical contact-based transformer with a contactless inductive transformer that uses electromagnetic fields for energy transmission. The primary winding on the stator and secondary winding on the rotor create magnetic coupling without physical contact, eliminating mechanical wear and electrical contact losses while maintaining reliable power transmission to the rotor

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Power

If a contact-based transformer is used for energy transmission, then power can be transmitted to the rotor, but wear and contamination occur

Engineering Contradiction:

Improvepower transmission capabilityVSAvoidwear and contamination

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent eliminates mechanical contact between stator and rotor components by using inductive coupling. The magnetic field couples the primary and secondary windings without physical contact, preventing wear and contamination while maintaining full power transmission capability to the rotor

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If a contactless inductive transformer with air gap is used, then mechanical losses are reduced, but the air gap must be large enough to prevent core contact, increasing installation space

Engineering Contradiction:

Improvemechanical lossesVSAvoidinstallation space

Core Design Contradiction:

Loss of energyVSVolume of stationary object

Solution Approach 1:

The patent integrates the inductive transformer components within the existing motor structure. The primary winding is incorporated into the stator assembly and the secondary winding into the rotor assembly, nesting the transformer functions within the motor's existing spatial envelope rather than adding external transformer components

Inventive Principle:

Principle #7Nested doll (Nesting)

4Stability of the object's composition

If core parts are attached to rotating parts, then support at fixed speed is achieved, but the air gap must be large to accommodate tolerances and operating conditions

Engineering Contradiction:

Improvefixed speed supportVSAvoidair gap size

Core Design Contradiction:

Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The patent optimizes the air gap dimensions to a specific range (0.5-2mm) that balances the need for mechanical tolerance accommodation with the desire for compact size. This parameter optimization allows small air gap transformers to operate reliably without requiring excessive clearance

Inventive Principle:

Principle #35Parameter changes

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 solution achieves a compact, reliable, and efficient energy transmission system that reduces mechanical and electrical losses, saves installation space, and improves thermal management, enabling high power transmission without overloading.

Implementation Method 1

An inductive transformer is usually a rotationally symmetrical transformer with an air gap consisting of a primary and a secondary winding

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

An inductive transformer is usually a rotationally symmetrical transformer with an air gap consisting of a primary and a secondary winding. As a rule, an inductive transformer also has a core made of ferrite, for example

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS20260066748A1Transformer for externally excited synchronous machines: integration via bearings

Publication Date: 2026.03.05 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A contactless energy transmission device for a rotor of an electric machine is disclosed. The device includes a housing part, which can be coupled in a rotationally rigid manner to a housing of the electric machine, and an inductive transformer which has an energizable primary coil and a secondary coil that is arranged at a distance thereto and can be electrically coupled to a winding of the rotor a roller bearing, by means of which a rotor shaft is rotatably mounted relative to the housing part, wherein the primary coil is positioned on the housing part in a rotationally rigid manner relative thereto, and the roller bearing is arranged within the housing part such that the primary coil and the roller bearing are arranged coaxially, and the secondary coil is arranged within a transformer housing.