Stator with Varying Tooth Thickness for Torque Ripple Reduction
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Solution Overview
Problem
Conventional electric machines experience torque ripple due to harmonic magnetic flux distributions, leading to driveline speed oscillations, vehicle vibration, and noise, particularly at low speeds, which existing solutions like rotor segment skewing techniques struggle to effectively attenuate, especially for high-order torque ripples like the 24th order.
Innovation Solution
A stator design with multiple metal laminations surrounding the rotor and featuring non-uniform angular spacing and varying stator tooth thicknesses, allowing for flexible electrical angles, angular displacements, and coil pitches, which interact with the rotor flux to reduce torque ripple components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If rotor segment skewing techniques are used to reduce torque ripple, then low-order torque ripple components are attenuated, but high-order torque ripple components (such as 24th order) cannot be effectively reduced
Solution Approach 1:
The patent applies local quality by varying the thickness of stator teeth at specific locations rather than using uniform thickness throughout. Different stator teeth have different thicknesses (first thickness vs. second thickness) to locally modify magnetic flux distribution and target specific high-order torque ripple components that uniform skewing cannot address.
Solution Approach 2:
The patent changes physical parameters of the stator teeth, specifically the thickness parameter, to alter magnetic flux characteristics. By adjusting stator tooth thickness, the invention modifies the electrical angle, angular displacement, and coil pitch parameters to effectively attenuate high-order torque ripple components.
2Object-generated harmful factors
If conventional stator designs with fixed electrical angles and coil pitches are used, then manufacturing is simplified, but the ability to reduce high-order torque ripple is limited
Solution Approach 1:
The patent introduces asymmetry by making stator teeth have non-uniform thicknesses around the stator circumference. This asymmetric design breaks the symmetry of conventional stators, enabling modification of magnetic flux patterns to reduce high-order torque ripple components while maintaining manufacturability.
Solution Approach 2:
The stator is segmented into multiple teeth with different thickness characteristics. Rather than treating the stator as a uniform structure, the invention divides it into discrete teeth that can have varying thicknesses, allowing independent optimization of each tooth's contribution to torque ripple reduction.
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 stator design significantly reduces torque ripple effects, including the 24th order component, resulting in minimized motor speed fluctuations and vibration, enhancing operational stability and reducing noise at low speeds.
Implementation Method 1
A magnetic flux flow pattern is developed when stator coils wound on the stator are energized with a multi-phase sinusoidal voltage
Implementation Method 2
the magnetic flux field of the magnets interacts with the magnetic flux field of stator electrical windings that are energized by a multiple-phase voltage
Implementation Method 3
the torque ripple created by a pole of each segment will tend to cancel the effect of the torque ripple of an adjacent pole so that the combined separate torque ripple components will be attenuated
Data Source
AI summary
A stator for an electric machine has a circular stator body surrounding a rotor with an air gap therebetween. The stator has radially extending slots that define radially extending stator teeth. Multiple electric windings are located in the slots to define peripherally spaced magnetic poles. Separate coil groups establish multiple phases for the electric machine. Motor torque ripple is attenuated by forming the stator teeth with different widths for a given coil group.