Brushless Synchronous Machine Trapezoidal EMF Rotor
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Solution Overview
Problem
Existing brushless synchronous machines energized by permanent magnets face limitations in power output and experience torque fluctuations due to quadrature inductance and magnetic flux distribution.
Innovation Solution
A brushless synchronous machine design featuring a stator with single-tooth windings and a rotor with embedded permanent magnets, where the rotor's outer contour is shaped to produce a trapezoidal electromagnetic force with a maximum value in a 30° to 90° electrical angle range, reducing quadrature inductance and eliminating the need for a security ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor outer contour is shaped to produce a trapezoidal electromagnetic force, then power output increases by 12%, but the machine complexity increases due to the non-standard rotor geometry
Solution Approach 1:
The rotor outer contour is modified from a conventional circular shape to a specific non-circular geometry defined by mathematical equations (R(α) = R1 + (R2-R1)*(1 - cos(α))/2 for 0≤α≤π). This parameter change in the rotor shape directly produces the desired trapezoidal electromagnetic force characteristic, increasing power output by 12% while maintaining manufacturability through precise geometric definition
Solution Approach 2:
The rotor employs a specifically curved outer contour that varies angularly to generate the trapezoidal EMF. The curvature is mathematically defined to ensure the electromagnetic force has a plateau region (30° to 90° electrical angle) where the maximum value is present uninterrupted, transforming the conventional sinusoidal EMF into a trapezoidal waveform that increases power output
2Reliability
If permanent magnets are embedded in the rotor with cutouts, then corrosion protection improves, but manufacturing precision requirements increase due to the embedding process
Solution Approach 1:
Permanent magnets are embedded within cutouts in the rotor core, with each magnet surrounded on all sides by rotor material. This nesting arrangement provides comprehensive corrosion protection as the rotor material acts as a barrier, while the cutouts are designed with specific dimensions (larger than the magnets in the perpendicular direction) to accommodate the magnets with appropriate clearance
Solution Approach 2:
The rotor structure combines different materials: the rotor core made of metal laminations, permanent magnets embedded in cutouts, and rotor material surrounding the magnets. This composite structure provides both corrosion protection through material enclosure and precise magnetic field generation through the embedded magnets
3Stability of the object's composition
If the rotor contour is shaped for trapezoidal EMF, then torque fluctuations are reduced, but the ease of manufacture decreases due to the complex rotor shaping
Solution Approach 1:
The rotor outer contour is defined by specific mathematical parameters and equations that describe the desired trapezoidal EMF characteristic. By precisely controlling the radial distance as a function of angular position, the design achieves reduced torque fluctuations while providing clear manufacturing guidelines for achieving the required geometry
Solution Approach 2:
The patent provides explicit mathematical equations for the rotor contour that can be directly implemented in manufacturing processes, allowing the complex geometry to be produced efficiently through computer-controlled machining or molding operations rather than requiring complex multi-step manufacturing procedures
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 increases power output by 12% and minimizes torque fluctuations, provides better corrosion and demagnetization protection for the magnets, and simplifies series production while reducing mechanical stresses and flux distribution issues.
Implementation Method 1
electromagnetic force (EMF) induced in the stator winding has a trapezoidal characteristic
Implementation Method 2
magnetic flux inhibitors are provided at least between a cutout for accommodating permanent magnets
Data Source
AI summary
A brushless synchronous machine is energized by permanent magnets with a stator and a rotor. The rotor is supported within the stator to allow rotation. The rotor has a plurality of cutouts into which permanent magnets are embedded. An air gap is provided between the stator and the rotor. The outer contour of the rotors is formed such that the electromagnetic force induced by the individual stator tooth winding has a trapezoidal characteristic. The maximum value of the electromagnetic force is present uninterrupted in an electrical angle range of 30° to 90°.