Brushless Multiphase Self-Commutation Controller for Wound-Rotor Stability
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Solution Overview
Problem
The Wound-Rotor [Synchronous] Doubly-Fed Electric Machine faces instability due to its reliance on sliding contacts and multiphase slip rings, making it difficult to synchronize frequency and voltage of rotor excitation, leading to torque instability and inefficiency.
Innovation Solution
The Brushless Multiphase Self-Commutation Controller (BMSCC) uses a Position Dependent Flux High Frequency Transformer (PDF-HFT) with integral synchronous modulators-demodulators and a Magnetizing Current Generator to establish an oscillating magnetic field, enabling compensated modulation and synchronized power transfer across the air gap without mechanical contact, thereby stabilizing the electric machine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If sliding contacts and multiphase slip rings are used for rotor excitation, then electrical power can be transferred to the rotating rotor, but mechanical instability and torque pulsation occur due to difficulty in synchronizing frequency and voltage
Solution Approach 1:
The patent replaces the mechanical sliding contact system (brushes and slip rings) with an electromagnetic field-based power transfer system. The primary winding on the stator and secondary winding on the rotor create a magnetic coupling that transfers power wirelessly across the air gap, eliminating mechanical wear and synchronization instability while maintaining power transfer capability.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the stator and rotor for power transfer. The oscillating magnetic field generated by the primary winding couples with the secondary winding on the rotor, serving as a mediator that transfers electrical energy without direct mechanical contact, thus resolving the stability issue.
2Ease of operation
If brushes and commutators are used for commutation, then electrical excitation can be provided to the rotor, but mechanical contact causes wear, sparks, and maintenance requirements
Solution Approach 1:
The patent eliminates the mechanical brush-commutator system by using electromagnetic induction for commutation. The rotating magnetic field automatically commutates the rotor currents through induction, replacing mechanical contact with field-based interaction, thereby eliminating wear and sparks while maintaining commutation functionality.
Solution Approach 2:
The system performs self-commutation through the rotating magnetic field, which automatically synchronizes the current distribution in the rotor windings based on its position. This self-service mechanism eliminates the need for external mechanical commutation devices, improving reliability while maintaining ease of operation.
3Extent of automation
If frequency and voltage synchronization is attempted with traditional controls, then commutation can be achieved, but complexity increases and stability decreases due to difficulty in maintaining synchronism
Solution Approach 1:
The patent implements self-synchronization through the inherent properties of the rotating magnetic field, which automatically maintains frequency and voltage synchronism between stator and rotor. This self-service approach eliminates complex control systems while achieving automatic commutation and stable operation.
Solution Approach 2:
The patent utilizes the periodic nature of the rotating magnetic field to automatically synchronize commutation. The field's rotation naturally creates periodic current patterns in the rotor windings that match the mechanical position, providing automatic frequency and voltage synchronization without complex control circuitry.
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
The BMSCC ensures stable and efficient operation by naturally synchronizing the electrical excitation with mechanical speed, reducing torque pulsation and electrical losses, and enhancing power density and reliability of the Wound-Rotor Doubly-Fed Electric Machine.
Implementation Method 1
The Brushless MultiphaseSelf-Commutation Controller (BMSCC) uses a Position Dependent Flux High Frequency Transformer (PDF-HFT) with integral synchronous modulators-demodulators and a Magnetizing Current Generator to establish an oscillating magnetic field, enabling compensated modulation and synchronized power transfer across the air gap without mechanical contact
Implementation Method 2
enabling compensated modulation and synchronized power transfer across the air gap without mechanical contact, thereby stabilizing the electric machine operation
Data Source
AI summary
The Brushless Multiphase Self-Commutation Controller or BMSCC is an adjustable speed drive for reliable, contact-less and stable self-commutation control of electric apparatus, including electric motors and generators. BMSCC transforms multiphase electrical excitation from one frequency to variable frequency that is automatically synchronized to the movement of the electric apparatus without traditional estimation methods of commutation and frequency synthesis using derivatives of electronic, electro-mechanical, and field-oriented-control. Instead, BMSCC comprises an analog electromagnetic computer with synchronous modulation techniques to first establish magnetic energy and then dynamically share packets of magnetic energy between phase windings of a multiphase, position dependent flux, high frequency transformer by direct AC-to-AC conversion without an intermediate DC conversion stage.