Segmented Ring Machine for Inverter Operation
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Solution Overview
Problem
Existing electrical machines, particularly ring machines, face challenges in achieving cost-effectiveness and efficiency due to thermal management issues and the need for redesigning for each power or torque class, leading to increased weight and cost, with limited modular structures that allow series production across different sizes.
Innovation Solution
A modular, segmented, multi-pole drive system with a partially covered ring machine design, utilizing a combination of radial and axial flux machines, where the stator is segmented and the rotor is laminated, allowing for passive cooling and reduced thermal expansion through segmentation and expansion joints, enabling scalable and fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the machine is designed as a closed ring structure, then mechanical strength and structural stability are improved, but thermal dissipation capability deteriorates due to limited cooling surface area
Solution Approach 1:
The ring machine is divided into multiple independent stator segments that can be separated along the circumferential direction. This segmentation increases the cooling surface area by exposing previously internal surfaces to the external environment, while maintaining structural stability through the modular segment design that preserves the overall ring structure when assembled.
2Reliability
If the air gap diameter is increased to reduce centrifugal load, then bearing life and reliability are improved, but torque density deteriorates due to reduced force generation capability
Solution Approach 1:
The patent transitions from a traditional radial flux machine to an axial flux ring machine configuration. This dimensional change allows the magnetic flux to pass axially through the rotor discs rather than radially, enabling torque generation in a different spatial dimension. This maintains compact radial dimensions (small air gap) while achieving high torque density through the axial flux path and multiple stacked rotor discs.
3Power
If high current coverage is used to increase power density, then output power is improved, but heat generation increases leading to thermal management issues
Solution Approach 1:
The stator is segmented into multiple independent modules, each with its own winding sets. This segmentation allows for distributed current paths and improved heat dissipation across multiple smaller cooling surfaces. The modular design enables better thermal management while maintaining high power density through optimized current distribution across segments.
Solution Approach 2:
Different stator segments can be optimized with locally adapted current densities and cooling configurations based on specific thermal and power requirements. This allows high current coverage in regions where cooling is effective, while reducing current density in thermally sensitive areas, achieving overall high power density with controlled heat generation.
4Adaptability or versatility
If a gearbox is added to achieve desired speed-torque characteristics, then adaptability to different applications is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent employs a variable flux density design where the magnetic flux can be dynamically adjusted through control of the excitation current. This enables the machine to adapt its torque-speed characteristics electronically without mechanical gear changes. The dynamic control of flux density allows the same machine configuration to serve multiple application requirements, replacing the need for gearboxes while maintaining versatility.
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 design significantly reduces thermal limit power, weight, development, and testing effort, while maintaining efficiency and cost-effectiveness, allowing for scalable and modular construction suitable for various applications.
Implementation Method 1
an electrical machine that is designed as a segmented ring machine... with at least one block of segments of the stator and a laminated rotor
Implementation Method 2
reduced thermal expansion through segmentation and expansion joints
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an arrangement in the form of an electric ring machine for inverter operation in the form of a reluctance machine, which is operated as a switched or synchronous reluctance machine, in which - by means of the arrangement of the stator design of the at least one stator block in radial or axial or combined design relative to the rotor structure, - at least one stator block only partially surrounds the ring rotor on its circumference, - the windings in tooth coil design or distributed design are implemented solely on the stator area, - the rotor ring in disc-shaped or drum-shaped design consists of a support structure and laminated ring segments for flux guidance and the rotor lamination structure is also divided into segments in its circumferential length,This creates recesses between the sheet metal segments, thereby decoupling the thermal expansion (heat loss) in the air gap diameter - and whose winding system of at least one stator block consists of at least 2 phases, which can be energized with at least 1 machine-side converter circuit per phase, - and the converter circuits have a synchronization option for phase energization,