Brushless Self-Excited Machine With Compensated Rotor Field Excitation
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Solution Overview
Problem
Electric machines relying on brushes and slip rings for current transfer suffer from maintenance issues due to physical contact, which leads to wear and potential failures, and limit packaging options.
Innovation Solution
A self-excited brushless machine with compensated field windings, featuring a rotor with field and auxiliary windings and a stator with multiphase windings, uses energy converters to induce currents and generate magnetomotive forces, allowing for wireless power transfer and reduced maintenance by eliminating the need for brushes and slip rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushes and slip rings are used to transfer current from stationary to rotating parts, then current transfer is achieved, but physical contact causes wear and maintenance requirements
Solution Approach 1:
The patent extracts and eliminates the brushes and slip rings from the system by implementing a brushless excitation system where the rotor winding is excited through electromagnetic induction from the stator, removing the problematic sliding contact components entirely
Solution Approach 2:
The patent replaces the mechanical contact-based current transfer system (brushes and slip rings) with an electromagnetic field-based system where current is transferred wirelessly through magnetic coupling between stator and rotor windings
2Ease of operation
If brushes and slip rings are used for current transfer, then current flow is enabled, but space for brushes and slip rings limits packaging options
Solution Approach 1:
The patent removes the brushes and slip rings components, freeing up the space they occupied and allowing for more flexible packaging arrangements and improved motor design freedom
Solution Approach 2:
The mechanical contact system is replaced with an electromagnetic coupling system that requires no physical contact components, thereby eliminating the space requirements for brush holders, slip rings, and associated mounting structures
3Ease of repair
If conventional brushless machines are used, then maintenance is reduced, but torque production efficiency decreases at various rotor speeds
Solution Approach 1:
The patent implements a dynamic control system that adjusts the excitation current in the rotor winding based on rotor speed to maintain optimal torque production efficiency across the entire operating range, while preserving the brushless maintenance-free design
Solution Approach 2:
The patent changes the excitation parameters (current magnitude and frequency) dynamically according to rotor speed to optimize torque production at each operating point, achieving high efficiency across variable speeds without compromising the maintenance-free advantage
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 solution enables efficient torque production and reduced maintenance by controlling magnetomotive forces and frequencies, maintaining high efficiency and torque at various rotor speeds without increasing harmonic current magnitude, and is applicable in electric vehicles to prevent demagnetization and enhance torque density.
Implementation Method 1
A third current is induced on auxiliary windings of a rotor of the machine using the second magnetomotive force
Implementation Method 2
A rotor field winding of the machine is excited with the induced currents of the auxiliary windings
Data Source
AI summary
A self-excited brushless machine with compensated field windings includes a rotor and a stator. The rotor Includes a field winding secured to the rotor, an auxiliary winding secured to the rotor, and an energy converter associated with the rotor and configured to convert current between the field winding and the auxiliary winding. The stator includes a multiphase winding. The self-excited brushless machine uses a first current to generate a first magnetomotive force on a stator of the machine, and uses a second current to generate a second magnetomotive force. A third current is induced on auxiliary windings of a rotor of the machine using the second magnetomotive force. A rotor field winding of the machine is excited with the induced currents of the auxiliary windings.