Phased Multi-Rotor Electric Machine for Stable Torque Output
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Solution Overview
Problem
Multi-rotor electric machines suffer from unsteady output torque characteristics and low durability due to torque variability at the rotor level, requiring complex configurations and expensive, high-strength gears that are prone to fretting damage.
Innovation Solution
The electric machine system comprises multiple rotors with phased rotary power driven by a common shaft via gears, where each rotor is magnetically indexed and connected through gears with phases offset by 120 degrees, reducing torque ripple and enhancing durability by distributing stress across multiple gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple rotors are used to enhance power output, then power capability is improved, but torque ripple and variability increase causing unsteady output characteristics
Solution Approach 1:
The patent applies periodic action by using multiple rotors driven by different phases of AC power (e.g., three-phase power with 120-degree phase differences). Each rotor receives power at a different phase angle, creating periodic torque pulses that are distributed uniformly over time. This results in the sum of torques being substantially constant, eliminating torque ripple while maintaining high power output capability.
2Adaptability or versatility
If complex configurations are used to achieve multi-rotor operation, then device functionality is improved, but structural complexity increases
Solution Approach 1:
The patent merges multiple electric machine systems into a single integrated structure where multiple rotors are coupled to a common output shaft. The stators of different phases are combined in a single housing, and the rotors share common magnetic circuit elements. This merging approach achieves multi-rotor functionality while reducing overall structural complexity compared to separate machines.
Solution Approach 2:
The patent implements universality by designing a single electric machine system that performs multiple functions: it generates power through multiple rotors simultaneously, provides constant torque output, and operates with different phase configurations. The common output shaft and shared magnetic circuit allow the system to function as an integrated multi-phase motor unit.
3Reliability
If high-strength gears are used to handle torque variability, then durability is improved, but cost and susceptibility to fretting damage increase
Solution Approach 1:
The patent achieves continuity of useful action by ensuring constant torque output through phased rotor operation. Since the sum of torques from multiple phased rotors is substantially constant, the gears experience uniform, continuous loading without the cyclic variations that cause fatigue and fretting. This allows the use of less expensive, standard-grade gears while maintaining high reliability.
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 provides improved operational characteristics and durability by reducing torque ripple and cyclic stress on gears, allowing for the use of less expensive materials and increasing the working life of the machine.
Implementation Method 1
a first electric machine having a plurality of first rotors driven using electric power having a first phase... a second electric machine having a plurality of second rotors driven using electric power having a second phase
Data Source
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AI summary
An electric machine system (800) described herein comprises a first and second electric machines (810, 810') configured to drive a load (104). The first electric machine (810) has a plurality of first rotors (802) driven using electric power having a first phase. The second electric machine (810') has a plurality of second rotors (802) driven using electric power having a second phase. The second phase differs from the first phase. One or more shafts (816) connect a first rotor (802) with a second rotor (802'). The first rotor (802) is coaxial with and axially spaced apart from the second rotor (802').