Rectified Rotor Windings for Synchronous Torque Ripple Control
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Solution Overview
Problem
Existing electric motors and generators face challenges in efficiently controlling torque ripple and maintaining synchronicity between the stator and rotor without relying on rare-earth magnets, brushes, or exciter circuits.
Innovation Solution
The implementation of a rectifier in the rotor windings, combined with a controller that adjusts current angle and magnitude in response to operating conditions, ensures synchronicity and reduces torque ripple by using direct coupling between the stator and rotor, eliminating the need for rare-earth magnets and separate exciter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare-earth magnets and exciter circuits are used to maintain synchronicity and control torque, then motor performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the exciter circuit from the motor structure. Instead of using a separate exciter circuit to provide rotor current, the invention uses the stator windings directly to induce current in the rotor windings through electromagnetic induction. This removal of the exciter circuit simplifies the overall device structure while maintaining the ability to control rotor current and maintain synchronicity.
Solution Approach 2:
The stator windings perform multiple functions: they generate the rotating magnetic field for motor operation and simultaneously serve as the excitation source for the rotor windings. This multi-functionality eliminates the need for separate exciter circuits and reduces device complexity while maintaining synchronicity control capability.
2Reliability
If brushes and commutators are used to energize rotor windings, then motor operation is enabled, but reliability and maintenance requirements worsen
Solution Approach 1:
The patent replaces the mechanical brush-commutator system with a fully electromagnetic induction system. Rotor windings are energized through electromagnetic induction from the stator magnetic field, eliminating all mechanical contact components. This substitution dramatically improves reliability by removing wear-prone parts and eliminates maintenance requirements associated with brush replacement.
3Reliability
If rectifiers are added to rotor windings to control current direction, then torque ripple is reduced, but device complexity increases
Solution Approach 1:
The rectifier function is merged directly into the rotor winding structure itself. Rather than adding separate rectifier circuits, the invention integrates rectifying elements (such as diodes) directly into the rotor coil windings, creating a unified structure that both generates and rectifies current in one integrated component assembly.
4Power
If separate exciter circuits and rare-earth magnets are used, then motor performance is achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates expensive rare-earth magnets from the motor structure. Instead of using permanent magnets made from rare-earth materials, the invention uses electromagnets created by current-carrying windings on both stator and rotor. This extraction of rare-earth materials significantly reduces manufacturing costs while maintaining the ability to generate required magnetic fields for motor operation.
Solution Approach 2:
The invention changes the fundamental parameter of magnetic field generation from permanent magnets (static magnetic properties) to electromagnets (dynamic magnetic properties controlled by current). This parameter change enables cost reduction by eliminating rare-earth materials while maintaining or improving motor performance through controllable electromagnetic fields.
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 approach enhances motor efficiency by reducing torque ripple and maintaining synchronicity, while avoiding the use of costly and complex components like rare-earth magnets and brushes, thus improving operational reliability and reducing costs.
Implementation Method 1
A rotor defines multiple fixed rotor poles with associated rotor windings that include a rectifier and are configured to be energized only by the stator. The rotor defines a rotor field energizable by magnetic fields produced by the stator windings to produce relative motion between the rotor and the stator.
Implementation Method 2
A rotor defines multiple fixed rotor poles with associated rotor windings that include a rectifier. The rectifier includes a diode. A delay of energization of flux in an air gap is reduced by a rectifier.
Implementation Method 3
A controller is configured to send a current through the stator windings at a current angle measured relative to a closest one of the rotor poles. The controller is configured to adjust the current angle in response to operating conditions. The rotor is maintained in synchronicity with the magnetic fields produced by the stator windings during operation.
Data Source
AI summary
An electric machine includes a stator defining multiple stator poles with associated stator windings configured to receive a stator current. The electric machine also includes a rotor defining multiple fixed rotor poles with associated rotor windings, wherein the rotor defines a field energizable by magnetic fields produced by the stator windings when receiving the stator current to produce relative motion between the rotor and the stator and wherein the rotor is maintained in synchronicity with the magnetic fields produced by the stator during operation of the electric machine. The electric machine also includes a rectification system configured control against an alternating current being induced in the rotor poles as the field is energized by magnetic fields produced by the stator windings when receiving the stator current.