Nested Exciter and PMG Rotor Layout for Compact Excitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing excitation systems for rotating electrical machines, such as synchronous generators, face challenges with complexity, increased rotor mass, and space constraints due to separate permanent magnet generators (PMGs) and exciters, which are often complex to manufacture and require external mounting, limiting their compactness and efficiency.
Innovation Solution
The integration of a common rotor core for both the exciter and PMG, where one is nested inside the other, reduces complexity and mass, allowing for a compact design with shared components and optional PMG inclusion, using a common stator core and bracket mounting for static components to minimize space and parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate PMG and exciter are provided in series on the shaft, then power supply independence is achieved, but axial space occupation increases
Solution Approach 1:
The PMG is nested inside the exciter structure, with the PMG rotor positioned within the exciter stator and the exciter rotor positioned within the PMG stator. This nesting arrangement allows both generators to share the same axial space on the shaft, achieving power supply independence while minimizing axial space occupation and overall system size.
Solution Approach 2:
The patent transitions from a series arrangement (occupying axial space) to a nested concentric arrangement (occupying radial space). By organizing the PMG and exciter in concentric cylinders around the shaft, the system achieves the same functional independence while reducing axial length and minimizing the overall footprint of the excitation system.
2Volume of moving object
If PMG is nested inside exciter, then axial space is minimized, but number of parts and manufacturing complexity increase
Solution Approach 1:
The common rotor core serves dual functions: it acts as the rotor for the exciter (with exciter windings) and simultaneously as the rotor for the PMG (with permanent magnets). This multi-functionality reduces the number of separate parts needed, as one rotor core replaces what would traditionally require two separate rotors, thereby simplifying manufacturing while maintaining the nested compact arrangement.
Solution Approach 2:
The patent merges the PMG and exciter into a single integrated unit sharing common components: a common rotor core, common bearings, and common shaft connection. This consolidation reduces the total number of parts compared to separate nested units, simplifies assembly, and reduces manufacturing complexity while achieving minimal axial space occupation.
3Ease of manufacture
If co-located stators are used, then assembly is facilitated and parts are reduced, but rotating mass increases
Solution Approach 1:
The patent segments the stators into two separate stators (PMG stator and exciter stator) that are positioned at different radial locations. This segmentation allows each stator to be optimized independently and reduces the rotating mass compared to a single large co-located stator, while still facilitating assembly through standardized mounting interfaces on the stationary structure.
4Adaptability or versatility
If external mounting is used, then space constraints are accommodated, but overall system size increases
Solution Approach 1:
The nested concentric arrangement of PMG inside exciter allows the entire excitation system to be mounted within the existing generator housing without external mounting. The compact nested structure fits within the available radial and axial space, eliminating the need for external mounting while minimizing the overall system size and maintaining adaptability to various space constraints.
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 achieves reduced complexity, lower material usage, simpler mounting, and smaller bearings, with optional PMG inclusion, enhancing manufacturing efficiency and reducing the overall size and weight of the excitation system.
Implementation Method 1
a permanent magnet generator (PMG) mounted on the generator shaft to provide the power for the exciter
Implementation Method 2
The rotor's magnetic field is produced by passing a DC current through windings in the rotor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An excitation system (15) is disclosed for providing excitation to a main rotating electrical machine (2). The excitation system comprises an exciter (50) and an auxiliary generator (52). The exciter and the auxiliary generator have separate stator cores (14, 18) and share a common rotor core (16). The common rotor (16) core may be located between the two stator cores (14, 18). This may help to optimize space, improve material usage and reduce the total rotating mass. A mounting arrangement for the common rotor core is also disclosed.