Multi-Rotor Electric Machine for Variable-Load Efficiency
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Solution Overview
Problem
Existing electric machines face challenges such as high cost and weight due to the use of copper in rotor windings, inefficiency in energy conversion, safety concerns from high current requirements, and radio frequency interference, as well as environmental issues from noise and vibration in wind turbines.
Innovation Solution
The development of an electric machine comprising a primary mechanical output or input and a plurality of electric sub-machines, with a controller that selectively engages or disengages sub-machines to operate at peak efficiency, using a drive train with multiple rotors and stators sharing common magnetic components to reduce material usage and torque, and employing a gear assembly with contra-rotating stages to minimize noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used for rotor windings, then electrical conductivity and reliability are improved, but weight and cost increase
Solution Approach 1:
The patent divides the single rotor into multiple rotors (first rotor and second rotor), each with its own windings. This segmentation allows the use of lighter materials in each individual rotor while maintaining overall system performance, as each rotor handles a portion of the total power requirement.
Solution Approach 2:
The patent combines multiple rotors with shared stator windings into a single integrated machine. The stator windings serve multiple rotors simultaneously, reducing the total amount of copper required compared to having separate motors, while still achieving the desired conductivity and reliability.
2Power
If high current is used to achieve high power, then power output is improved, but safety concerns and radio frequency interference increase
Solution Approach 1:
The patent segments the high current requirement across multiple parallel rotor circuits. Each rotor operates at a lower current level than a single rotor would require, thereby reducing radio frequency interference and improving safety while maintaining the same total power output through combined operation of multiple rotors.
3Power
If a single large rotor is used, then power density is improved, but efficiency across varying power demands deteriorates
Solution Approach 1:
The patent implements dynamic control where the controller selectively activates specific rotors based on the instantaneous power demand. This allows the system to operate efficiently across a wide range of power levels by engaging only the necessary number of rotors, avoiding the energy losses associated with operating a single large rotor at partial load.
Solution Approach 2:
The patent changes the operational parameters by allowing different rotors to be activated depending on power requirements. This parameter change enables the system to maintain high efficiency across varying loads by matching the active rotor configuration to the demanded power level, rather than operating a fixed single-rotor configuration.
4Weight of moving object
If multiple independent motors are used to reduce torque per motor, then weight and cost are reduced, but device complexity increases
Solution Approach 1:
The patent merges multiple rotors with a common stator winding system into a single integrated machine structure. This combination reduces the overall weight and cost compared to using multiple independent motors, while the shared stator components minimize the increase in device complexity that would otherwise result from having separate motor assemblies.
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 solution results in a more efficient, lighter, and cost-effective electric machine with reduced radio frequency interference, improved energy conversion efficiency, and lower environmental impact, suitable for various applications including wind turbines.
Implementation Method 1
Most electric motors utilise the electromagnetic effect to convert energy from electrical to mechanical. This typically involves placing a rotor within a magnetic field established by a stator.
Implementation Method 2
Electrical generators use a mechanical input to produce electrical power... This typically involves placing a conductive rotor within a magnetic field established by a stator and rotating the rotor to generate a current therein.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
An electric machine (100) has a primary mechanical output or input, a plurality of electric sub-machine rotors (102) each having an output or input shaft (104), a plurality of electric sub-machine stator magnets proximate the rotors, a drive train connecting each of the output or input shafts of the plurality of electric sub-machine rotors to simultaneously drive, or be driven by, the primary output shaft. Each sub- machine is selectively engaged or disengage depending on machine power.