Brushless Multiphase Self-Commutation Controller for Doubly-Fed Machines
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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 difficulty in synchronizing frequency and voltage of rotor excitation, leading to inefficient power transfer and high electrical losses, which limits its practical application.
Innovation Solution
The Brushless Multiphase Self-Commutation Controller (BMSCC) employs a Position Dependent Flux High Frequency Transformer (PDF-HFT) with integral synchronous modulators-demodulators and a Magnetizing Current Generator to establish oscillating magnetic fields, enabling compensated modulation and power transfer without mechanical contact, thus stabilizing the machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sliding contacts are used for rotor excitation, then electrical connection is established, but stability deteriorates and electrical losses increase
Solution Approach 1:
The patent replaces the mechanical sliding contact system with an electromagnetic field-based energy transfer system. The rotor excitation is achieved through magnetic coupling between stator and rotor windings, eliminating the need for physical electrical contacts. This substitution removes the inherent instability and electrical losses associated with sliding contacts while maintaining the necessary electrical connection for rotor excitation.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary medium to transfer energy between the stator and rotor. Instead of direct electrical contact through sliding contacts, the excitation energy is transmitted through the air gap via magnetic coupling, with the magnetic field acting as the intermediary that enables energy transfer without physical contact.
2Ease of operation
If sliding contacts are used for rotor excitation, then electrical connection is established, but device complexity increases
Solution Approach 1:
The patent eliminates the mechanical sliding contact assembly entirely, replacing it with a purely electromagnetic system. This removal of mechanical components simplifies the overall device structure, reduces the number of parts that require maintenance, and improves ease of operation by eliminating the complexity associated with contact wear, alignment, and replacement.
3Power
If frequency and voltage synchronization is difficult to achieve, then rotor excitation can be applied, but power transfer efficiency deteriorates
Solution Approach 1:
The patent implements a control system that monitors the electrical parameters and adjusts the rotor excitation frequency and voltage to maintain synchronization with the stator field. This feedback mechanism ensures optimal power transfer by continuously adapting the excitation parameters to match the operating conditions, thereby maximizing efficiency and minimizing energy losses.
Solution Approach 2:
The patent employs dynamic adjustment of the rotor excitation parameters to maintain optimal synchronization. The system automatically adapts the frequency and voltage of the rotor excitation in real-time based on the operating conditions, ensuring that the magnetic fields remain synchronized and power transfer efficiency is maximized throughout varying load conditions.
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 system enhances the stability and efficiency of the Wound-Rotor Doubly-Fed Electric Machine by allowing brushless speed-synchronized excitation, reducing electrical losses, and improving power transfer, making it suitable for high-performance applications.
Implementation Method 1
The Magnetizing Current Generator (MCG) means gates magnetizing current flow through the PDF-HFT core at a frequency within the design criteria of the PDF-HFT
Implementation Method 2
The synchronous modulators-demodulators transfer power between primary and secondary windings through electromagnetic coupling in the PDF-HFT
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.