Electric machine with contactless energy transfer for rotor excitation
The electric machine with a contactless inductive coupler for rotor excitation addresses mechanical wear and material limitations, achieving high efficiency and high power density, suitable for various motor types and applications.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-02
AI Technical Summary
Conventional electric motors with rotor excitation using brushes or slip rings face issues of mechanical wear, spark formation, electrical losses, speed limitations, high maintenance costs, and dependence on rare earth materials, while permanent magnet synchronous motors suffer from material costs, temperature problems, and limited field controllability.
An electric machine design featuring a stator excitation coil and a rotor receiving coil forming an inductive coupler for contactless energy transfer, with electronic rectification of induced alternating voltage to generate a controllable electromagnetic rotor field, applicable to both axial and radial flux machines.
Enables maintenance-free operation, high efficiency, and high power density without mechanical wear or rare earth materials, suitable for high-speed applications and compatible with axial flux motors, functioning as both a motor and generator.
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Abstract
Description
1. Technical field
[0001] The invention relates to electrical machines, in particular electric motors and generators, in which the rotor generates a controllable magnetic field, wherein the energy for generating the rotor excitation is transferred contactlessly from the stator to the rotor. The invention relates to both radial and axial flux machines as well as hybrid forms. 2. Purpose of the invention
[0002] In conventional electric motors with rotor excitation, brushes or slip rings are used to transfer electrical energy to the rotor. This leads to: mechanical wear Spark formation Maintenance costs electrical losses Speed limitation short lifespan
[0003] At the same time, there are disadvantages to permanent magnet synchronous motors (PMSM), in particular: Dependence on rare earths high material costs Temperature problems with magnets limited field controllability
[0004] The object of the invention is to provide an electric machine that: no slip rings or brushes are needed no permanent magnets required, provides a strong, controllable rotor field, enabling completely contactless energy transfer to the rotor, applicable to both axial and radial motors, High efficiency and high power densities are possible. 3. Solution to the problem (core invention)
[0005] The task is solved by an electric machine that: a) Has at least one excitation coil (primary coil) in the stator, b) The rotor has at least one receiving coil (secondary coil), c) The coils together form an inductive coupler, whereby electrical energy is transferred from the stator to the rotor without contact.
[0006] The following also applies: d) The alternating voltage induced by the coupler in the rotor is electronically rectified, e) The DC voltage thus generated feeds the rotor excitation coil, f) The rotor excitation coil generates a controllable electromagnetic rotor field, g) The machine can be designed as a radial or axial flux machine, h) The coupler can be operated resonantly, i) the rotor control electronics adjust the rotor field variably. 4. Advantages of the invention No mechanical contact → maintenance-free No permanent magnet → no neodymium, sustainable rotor field fully controllable (load, speed, field weakening) No wear parts → long service life High-speed capable, as there are no slip rings Compatible with axial flux motors (high torque density), energy-efficient RF transmission possible functions as a motor and as a generator Modular for industry, vehicles, wind power, etc. 5. Description of preferred embodiments 5.1 Inductive coupler
[0007] The coupler can be implemented as: axial coupler (disc-shaped) radial coupler (ring-shaped) toroidal coupler multipole coupler resonant LC coupler (primary + secondary tuned)
[0008] The air gap between the coils remains constant during operation. 5.2 Energy transfer
[0009] The coupler can be operated with: low-frequency AC high frequency AC (e.g. 10-200 kHz) resonant energy transfer method (high efficiency)
[0010] The secondary voltage is rectified and smoothed in the rotor. 5.3 Rotor Excitation
[0011] The rotor contains an excitation coil (or several) which: DC field generated Field strength adjustable acts as a synchronous rotor does without permanent magnets 6. Claims for protection (broadly formulated) Description of figures Fig. Figure 1 shows a schematic sectional view of an electric motor with contactless energy transfer for rotor excitation.
[0012] The electric motor comprises a stator (1) and a rotor (2) which is rotatably mounted relative to it.
[0013] The stator (1) is associated with at least one transmitting coil (3) which is designed for inductive energy transfer.
[0014] The rotor (2) is associated with a receiver coil (4) which is inductively coupled to the transmitting coil (3) via an air gap (5).
[0015] The energy received by the rotor (2) is used to excite a rotor field.
[0016] The electric motor is also connected to a control unit (6) which supplies at least the stator (1) with electrical energy.
[0017] The rotor (2) is supported via a shaft (7), the support being provided by means of at least one bearing (8).
[0018] The electric motor is enclosed by a housing (9). Reference symbol list 1 Stator 2 Rotor 3 transmitting coil 4 receiver coil 5 air gap 6 Control 7th wave 8 bearings 9 cases