Electric Rotating Machine Torque Ripple Reduction
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Solution Overview
Problem
Electric rotating machines face challenges in minimizing torque ripple, which leads to increased oscillation, noise, and reduced efficiency, especially in hybrid and electric vehicles, where high torque density and low electromagnetic noise are required.
Innovation Solution
The design incorporates a rotor with a specific outer diameter ratio to the stator, along with strategically placed permanent magnets in a 'V' shape configuration, and optimized stator tooth and slot dimensions to minimize torque ripple, reduce noise, and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are arranged in a V-shape configuration to increase reluctance torque, then torque density is improved, but torque ripple increases
Solution Approach 1:
The patent optimizes the V-shape angle of permanent magnets, the air gap length, and the ratio of rotor outer diameter to stator inner diameter to minimize torque ripple while maintaining high torque density. Specific parameter ranges are provided to achieve the balance between torque production and torque ripple reduction.
2Weight of moving object
If miniaturization is pursued to increase output density, then weight and volume are reduced, but electromagnetic noise and torque ripple increase
Solution Approach 1:
The patent specifies optimal parameter ranges including the ratio of rotor outer diameter to stator inner diameter (0.60-0.65), air gap length (0.005-0.015 times stator inner diameter), and V-shape angle (30-60 degrees) to minimize electromagnetic noise and torque ripple while achieving miniaturization and high output density.
3Power
If V-shape permanent magnet configuration is used to enhance reluctance torque, then inductance ratio is improved, but higher order space harmonics overlap flux waveform
Solution Approach 1:
The patent optimizes the V-shape angle of permanent magnets and the air gap length to control the inductance ratio and minimize space harmonics. The specific parameter ranges provided ensure that reluctance torque is maximized while preventing excessive space harmonics that would cause flux waveform distortion.
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 configuration results in a high-quality machine operation with reduced vibration, noise, and losses, achieving efficient torque production while minimizing torque ripple and electromagnetic noise.
Implementation Method 1
magnet torque in the form of attraction and repulsion derived from interference with said permanent magnets
Implementation Method 2
reluctance torque derived from magnetic flux passing through said teeth, rear surface side of the teeth and said rotor
Data Source
AI summary
The present invention provides an electric rotating machine capable of providing a high quality and efficient machine operation with reduced oscillation and noise by lowering torque ripple. The electric rotating machine includes a stator having a plurality of teeth facing a rotor, and a plurality of slots providing spaces for winding coils around the teeth. The rotor has a pair of permanent magnets embedded therein and located in a “V” shape configuration so as to let magnetic force act on the teeth such that the rotor within said stator is driven to revolve by reluctance torque and magnet torque. An outer diameter ratio Δ of an outer diameter Dr of the rotor to an outer diameter Ds of the stator falls in a range from 0.61 to 0.645.