Integrated Electrical Machine Torque Control
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Solution Overview
Problem
Current magnetic gearing systems in blended electric hybrid vehicles are complex, requiring two electrical machines and separate inverters, which increases cost, size, weight, and reduces reliability and dynamic performance.
Innovation Solution
An electrical machine design with a first rotor producing a magnetic field with a specific number of pole pairs, a second rotor with pole pieces to modulate the field, and a stator with windings to interact with both, allowing for variable torque and speed ratios without the need for a second electrical machine, using a single inverter system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two electrical machines and separate inverters are used in magnetic gearing systems, then torque and speed control is achieved, but device complexity, cost, and weight increase
Solution Approach 1:
The patent combines two separate electrical machines into a single integrated electrical machine with a common stator and two rotors (inner rotor and outer rotor). This merging eliminates the need for separate inverters and reduces overall system complexity while maintaining the ability to control torque and speed independently for each rotor, thereby improving reliability without sacrificing control capability.
Solution Approach 2:
The single electrical machine is designed to perform multiple functions: it provides magnetic gearing between the two rotors, enables independent torque control for each rotor, and allows variable speed ratio control. The common stator with windings generates magnetic fields that interact with both rotors simultaneously, making the system multi-functional and reducing the number of components needed.
2Force
If two electrical machines are used for magnetic gearing, then torque transmission is achieved, but cost and weight increase
Solution Approach 1:
The patent merges two electrical machines into one by sharing a common stator structure and winding system. The inner rotor and outer rotor both interact with the same stator magnetic field, allowing torque transmission between them while eliminating the weight of a second complete electrical machine assembly, including its separate stator, windings, and inverter.
Solution Approach 2:
The electrical machine features a nested configuration where the inner rotor is positioned inside the outer rotor, both surrounding a common stator. This nested arrangement allows both rotors to be part of the same mechanical and magnetic system, enabling torque transmission through magnetic interaction while minimizing overall system weight compared to two separate machines.
3Device complexity
If a single electrical machine with two rotors is used, then device complexity is reduced, but control precision may be affected
Solution Approach 1:
Although the electrical machine is physically integrated, the control system segments the torque control by independently controlling the current in the windings to generate separate magnetic field components that interact with each rotor. This allows independent torque control for the inner and outer rotors, maintaining precise torque ratio control despite the unified physical structure.
Solution Approach 2:
The control system adjusts magnetic field parameters (current magnitude, frequency, and phase) to independently control the interaction between the stator field and each rotor. By changing these parameters, the system can precisely control the torque ratio and speed ratio between the two rotors, maintaining measurement precision while using a single integrated machine.
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 design simplifies the power train by eliminating the need for a second electrical machine, reducing complexity, cost, and weight while maintaining efficient torque and speed control, enhancing reliability and dynamic performance.
Implementation Method 1
a first rotor producing a first magnetic field having a first number of pole pairs
Implementation Method 2
a second rotor with pole pieces to modulate the first magnetic field to produce a second magnetic field with a second number of pole pairs
Implementation Method 3
a stator with windings to produce a third magnetic field with the first number of pole pairs and the second number of pole pairs; the interaction of the third magnetic field with the first number of pole pairs and the second number of pole pairs changes a torque ratio between the first rotor and the second rotor
Data Source
AI summary
An electrical machine comprising: a first rotor, the first rotor producing a first magnetic field having a first number of pole pairs; a second rotor comprising a plurality of pole pieces, the plurality of pole pieces being arranged to modulate the first magnetic field to produce a second magnetic field having a second number of pole pairs; a stator Comprising one or more windings arranged to produce a third magnetic field arranged to interact with the first number of pole pairs and the second number of pole pairs; wherein the interaction of the third magnetic field with the first number of pole pairs and the second number of pole pairs changes a torque ratio between the first rotor and the second rotor.