Segmented Electric Motor Switching for High-Speed Efficiency
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Solution Overview
Problem
Existing electric motor systems face inefficiencies at high speeds due to high field weakening currents required to counteract back EMF, particularly in AC permanent magnet motors used in electric vehicles, where the approach of selectively magnetically decoupling the stator and rotor does not effectively reduce power consumption.
Innovation Solution
The electric motor is designed with multiple rotor and stator sections that can be mechanically and electrically decoupled, allowing for optimal power and torque distribution through clutches and switches, enabling continuous operation without high field weakening losses by adjusting the number of active sections based on speed and demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If field weakening currents are applied to counteract back EMF at high speeds, then the motor can maintain rotation, but motor efficiency is reduced due to large power consumption
Solution Approach 1:
The motor is divided into multiple independent motor sections, each with its own stator and rotor. By selectively activating only the necessary number of sections based on speed and torque requirements, the system reduces overall power consumption while maintaining high-speed operation capability.
Solution Approach 2:
Instead of applying field weakening currents across the entire motor, the system applies magnetic decoupling selectively to specific motor sections. This partial action approach reduces the total power consumption while still enabling high-speed operation when needed.
2Speed
If the rotor is axially shifted out of the stator envelope to reduce back EMF, then motor speed can be increased with constant power input, but motor torque is reduced
Solution Approach 1:
The motor is segmented into multiple independent sections that can be selectively activated. By engaging additional sections when high torque is required, the system can maintain torque output while operating at high speeds, avoiding the torque reduction associated with axial rotor shifting.
Solution Approach 2:
The system changes the operational parameters by adjusting the number of active motor sections based on the torque-speed requirements. This allows the motor to operate in different configurations: fewer sections for high-speed constant power operation, and more sections for high-torque applications.
3Force
If current is supplied throughout the whole stator during rotor axial shifting, then the motor can generate torque, but unneeded current is generated in the portion of the stator that does not overlap with the shifted rotor
Solution Approach 1:
The stator is divided into multiple independent stator sections corresponding to each motor section. By selectively activating only the stator sections that are currently overlapping with the rotor, the system eliminates energy losses from current flowing through non-overlapping stator portions.
Solution Approach 2:
The system dynamically adjusts which stator sections are active based on the real-time position and configuration of the rotor sections. This dynamic activation ensures that current is only supplied to stator sections that are currently contributing to torque generation, minimizing energy losses.
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 modular design allows for efficient operation across various speed ranges by optimizing the number of active motor sections, reducing field weakening losses and maintaining efficiency during high-speed and partial load conditions, such as highway driving.
Implementation Method 1
Rotation of the rotor may be generated through interaction between the permanent magnets embedded therein and rotating magnetic fields generated by the conductive windings within the stator, the latter of which may be generated through application of an AC voltage to the conductive windings of the stator
Implementation Method 2
the embedded permanent magnets within the rotor may cause the rotor to rotate in order to align their own magnetic field with that of the rotating magnetic field generated by the conductive windings of the stator (magnetic torque)
Implementation Method 3
In an electric motor, a back EMF is generated in response to the changing magnetic flux through the rotor due to the rotation of the rotor, opposing the applied voltage to the conductive windings within the stator
Data Source
AI summary
Methods and systems are provided for operating an electric motor including multiple rotor and stator sections. In one example, a system may include the multiple rotor sections configured to be mechanically coupled and decoupled from each other concurrently with multiple stator sections configured to be electrically coupled and decoupled from each other, within certain regimes of operation of the electric motor.