Wind Turbine Generator Asymmetric Stator Rotor Pole Configuration
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Solution Overview
Problem
Variable-speed wind turbines require complex electrical generation systems to convert variable-frequency AC power to constant-frequency AC for utility grids, leading to increased costs due to the use of numerous components and potential harmonic distortion, while existing solutions are expensive and inefficient.
Innovation Solution
A generator with a rotor and stator configuration using diode rectifiers, where stator coils share common diode rectifiers and are arranged in an asymmetric distribution to minimize cogging torque and vibration, allowing for the generation of a stable DC voltage suitable for a DC link capacitor, eliminating the need for a generator-side converter and reducing harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex converter system with multiple active rectifiers and switching devices is used to convert variable-frequency AC to constant-frequency AC, then the frequency conversion capability is improved, but the system cost and device complexity increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex generator-side converter from the system by using a direct-drive generator design where the generator rotor is directly connected to the wind turbine rotor without a gearbox, and the stator output is directly connected to the grid through a simple transformer, removing the need for complex frequency conversion equipment at the generator side
Solution Approach 2:
Instead of using active rectifiers and switching devices to actively convert frequency, the patent uses a passive approach with a direct-drive generator where the variable frequency output is directly transformed through a transformer, inverting the conventional approach of active frequency conversion
2Adaptability or versatility
If a complex converter system with multiple active rectifiers and switching devices is used to convert variable-frequency AC to constant-frequency AC, then the frequency conversion capability is improved, but the system cost increases due to the large number of components
Solution Approach 1:
The patent removes the expensive active converter system with multiple rectifiers and switching devices, replacing it with a simple direct-drive generator and transformer configuration that dramatically reduces component count and manufacturing cost
Solution Approach 2:
The patent uses simple, inexpensive passive components (transformer) instead of expensive active power electronic devices, accepting that the transformer is a robust, simple component that can be easily replaced if needed
3Device complexity
If a conventional generator with equal number of stator poles and rotor pole shoes is used, then the generator structure is simple and symmetric, but cogging torque and vibration increase
Solution Approach 1:
The patent deliberately creates an asymmetric configuration where the number of stator poles differs from the number of rotor pole shoes, which breaks the symmetry that causes cogging torque and vibration while maintaining a relatively simple generator structure
Solution Approach 2:
The patent applies different pole configurations to the stator and rotor, creating localized asymmetry in the magnetic field distribution that reduces cogging effects without requiring complete redesign of the entire generator structure
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 simplifies the generator configuration, reduces costs, and minimizes harmonic distortion, enabling efficient energy conversion and reduced noise and vibration, making it suitable for variable-speed wind turbines.
Implementation Method 1
a means for producing a magnetic field, e.g. one or more permanent magnets
Implementation Method 2
a stator with a number C of stator coils wound on the stator... during rotation of the rotor, each coil of the group carries a synchronous identical voltage form over time
Data Source
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AI summary
The invention describes a generator (1) comprising a rotor (2) with a number M of magnetic rotor pole shoes (3) and a means for producing a magnetic field, a stator (5) with a number C of stator coils (7, S1,1, S2,1, S3,1, S1,2, S2,2, ..., S1,c, S2,c, S3,c) wound on the stator (5) , and a generator-utility grid interface comprising a plurality of diode rectifiers (11, 11', 11"), whereby each diode rectifier (11, 11', 11") is connected to a stator coil (7, S1S1,1, S2,1, S3,1, S1,2, S2,2, ..., S1,c, S2,c, S3,c). Thereby the number C of stator coils (7, S1,1, S2,1, S3,1, S1,2, S2,2, ..., S1,c, S2,c, S3,c) is greater than the number M of rotor pole shoes (3), or the number M of rotor pole shoes (3) is greater than, but not an integer multiple of, the number C of stator coils (7, S1,1, S2,1, S3,1, S1,2, S2,2, ..., S1,c, S2,c, S3,c). The invention further describes a wind turbine (2) using the generator of the present invention and a method of assembling such a generator (1).