Multi-Rotor Electric Machine Gear Phasing for Torque Stability
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Solution Overview
Problem
Multi-rotor electric machines experience unsteady output torque characteristics and low durability due to variability in torque at the rotor level, requiring complex configurations and high-strength, expensive gears that are prone to fretting damage.
Innovation Solution
The electric machine system comprises multiple rotors with phased indexing and gear configurations that provide torque phase offsets between rotors, reducing torque ripple and cyclic stress on gears, and allowing for the use of less expensive materials while maintaining reliability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple rotors are used to enhance power output, then power increases, but torque ripple and cyclic stress increase causing unsteady output torque characteristics
Solution Approach 1:
The system divides the power generation function across multiple independent rotors (first rotor, second rotor, third rotor) that can be independently controlled. Each rotor processes a different phase of the AC waveform, segmenting the overall power output into manageable components that can be individually optimized and controlled to reduce torque ripple.
Solution Approach 2:
The system utilizes periodic action by processing different phases (A, B, and C phases) of the AC waveform through separate rotors at different times. Each rotor operates on a specific phase sequence, creating a periodic pattern where the combined output smooths out torque variations. The rotors are activated in a phased sequence that aligns with the AC waveform periods, ensuring continuous and stable power output.
2Reliability
If high-strength gears are used to withstand cyclic stress, then durability improves, but cost and complexity increase
Solution Approach 1:
The system implements periodic action by operating rotors in a phased sequence that aligns with AC waveform periods. Each rotor processes a specific phase (A, B, or C) at predetermined times, creating a periodic pattern of torque application. This periodic operation allows gears to experience controlled, predictable cyclic stress rather than continuous random loading, enabling the use of standard-strength materials while maintaining durability.
Solution Approach 2:
The system applies preliminary action by pre-coordinating the activation and phasing of each rotor before operation begins. The control system pre-establishes the phase relationships and timing sequences for each rotor, ensuring that torque loads are distributed optimally across the gear train from the start. This preliminary configuration allows the mechanical components to be designed for predictable rather than unpredictable loading patterns.
3Reliability
If complex configurations are used to manage torque variability, then torque stability improves, but device complexity increases
Solution Approach 1:
The system segments the power generation function across three independent rotors, each handling a specific phase of the AC waveform. This segmentation allows each rotor to be optimized for its specific function while the collective system provides torque stability. The modular segmented architecture actually reduces overall complexity compared to a single-rotor design attempting to handle all phases simultaneously.
Solution Approach 2:
The system uses periodic action to manage torque variability by processing different AC phases through separate rotors in a predetermined sequence. Each rotor activates periodically according to its phase assignment, creating a rhythmic pattern of torque application that naturally smooths output. This periodic coordination provides torque stability through temporal distribution rather than spatial complexity.
Data Source
AI summary
An electric machine system described herein comprises a first electric machine rotor, a first gear and a second gear. The first gear is connected to the first electric machine rotor and to a first input/output shaft. The second gear is connected to the first electric machine rotor and to a second input/output shaft. The first electric machine rotor is disposed between the first gear and the second gear.