Electric Machine Vector Control for Rotor Synchrony and Torque Ripple
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Solution Overview
Problem
Existing electric motors and generators face inefficiencies and operational challenges due to reliance on rare-earth magnets, separate brush or exciter circuits, and limited frequency response, particularly in maintaining synchronicity and controlling torque ripples.
Innovation Solution
The development of an electric machine with a field wound synchronous motor design featuring shorted, concentrated windings and a controller that adjusts current magnitude and angle in response to operating conditions, eliminating the need for rare-earth magnets and separate exciter circuits, and utilizing direct coupling for power and signal transfer between the stator and rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rare-earth magnets are used in the rotor, then magnetic field strength is improved, but cost and supply reliability deteriorate
Solution Approach 1:
The patent extracts and eliminates the dependency on rare-earth magnets by using a wound field rotor design where the magnetic field is generated electromagnetically through rotor windings energized by a separate exciter circuit, rather than relying on permanent magnets made from rare-earth elements
Solution Approach 2:
The patent introduces an exciter circuit as an intermediary component that generates the magnetic field in the rotor windings, replacing the direct use of rare-earth magnets and providing a controllable alternative that improves supply reliability
2Ease of operation
If separate brush or exciter circuits are used, then rotor field control is improved, but device complexity increases
Solution Approach 1:
The patent uses an exciter circuit as an intermediary to provide controlled DC current to the rotor windings, enabling precise control of the rotor magnetic field strength and orientation while maintaining a manageable system architecture
Solution Approach 2:
The patent enables dynamic control of the rotor field by adjusting the current magnitude and angle through the exciter circuit, allowing optimization of torque production and efficiency under different operating conditions
3Ease of manufacture
If conventional windings are used, then manufacturing is simplified, but frequency response and transient damping deteriorate
Solution Approach 1:
The patent segments the rotor windings into concentrated coils distributed around the rotor circumference, with each coil independently energized by the exciter circuit, enabling improved frequency response and transient damping while maintaining manufacturing feasibility
Solution Approach 2:
The patent implements dynamic control of the rotor field by continuously adjusting the exciter current magnitude and angle in response to operating conditions, enabling the system to respond rapidly to changes in load and speed
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 enhances operational efficiency, reduces reliance on rare-earth elements, and effectively controls torque ripples and transient damping across a wide range of frequencies, improving the overall performance and reliability of electric machines.
Implementation Method 1
Electric current is translated into electromagnetic fields which exert a mechanical force, or torque, between the stator and the rotor
Implementation Method 2
The rotor is configured to rotate in response to a magnetic field produced by the stator windings
Implementation Method 3
The controller is configured to send a current through a stator winding at a current angle measured from the closest one of the rotor poles. The controller is configured to adjust a current magnitude of the sent current in response to operating conditions
Data Source
AI summary
An electric machine includes a stator and a rotor energizable by magnetic fields produced by the stator when receiving a stator current to produce relative motion between the rotor and the stator. A controller is configured to send the stator current through the stator at a current angle measured from the closest one of a pole of the rotor, determine a desired operational output of the electric machine, and determine a desired rotor motion corresponding to the desired operational output of the electric machine. The controller is further configured to calculate a vector control modulation applied to the stator that elicits the desired rotor motion, and adjust the current angle of the stator current based on the vector control modulation to cause the rotor to perform the desired rotor motion and achieve the desired operational output of the electric machine.