Rotor Power Transfer Circuit With Parallel Brush Loops
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The physical and electrical dynamics of brushes and slip rings in rotor power transfer circuits for electric machines limit switching frequency and introduce tracking difficulties, leading to constraints in exciting rotor windings.
Innovation Solution
A rotor power transfer circuit utilizing a multiple leaf DC-DC converter with parallel branches and independent brush loops, allowing for simultaneous excitation of rotor windings with reduced current density and lower electromagnetic interference through superposition of current waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushes and slip rings are used for power transfer to rotor windings, then electrical connection is established, but switching frequency is limited and tracking difficulties occur
Solution Approach 1:
The invention divides the single brush loop into two independent brush loops (first and second brush loops), each capable of carrying excitation current. This segmentation allows the system to operate at higher switching frequencies by distributing the current burden and reducing the electrical dynamics constraints that limit single-loop systems.
Solution Approach 2:
The invention combines the outputs of two independent DC-DC converters through parallel connection to the rotor windings. This merging of power paths enables higher effective switching frequency and improved tracking by allowing simultaneous excitation through multiple independent channels.
2Device complexity
If single brush loop is used for rotor excitation, then circuit simplicity is maintained, but current density per brush is high limiting brush selection
Solution Approach 1:
By segmenting the excitation current path into two separate brush loops, the current density per brush is reduced. This allows selection from a wider variety of brush types and sizes while maintaining acceptable electrical performance, as each brush handles only a portion of the total excitation current.
3Power
If high current is transferred through single brush loop, then power transfer is achieved, but electromagnetic interference increases
Solution Approach 1:
The invention segments the high current transfer function into two parallel brush loops, each carrying a portion of the total excitation current. This distribution reduces the current magnitude in each individual loop, thereby reducing electromagnetic interference while maintaining the required total power transfer capability to the rotor windings.
Solution Approach 2:
The invention merges the current paths of two independent DC-DC converters in parallel at the rotor winding connection point. This merging allows the system to achieve high power transfer capability while each individual brush loop operates at lower current levels, reducing electromagnetic interference from each path.
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 enables improved tracking and reduced electromagnetic interference, allowing for a wider variety of brushes and enhanced performance in exciting rotor windings.
Implementation Method 1
a multiple leaf direct current (DC)-to-DC (DC-DC) converter having a plurality of branches connected in parallel to a source of DC power, with each branch including a plurality of switches operable for selectively controlling DC power transfer therethrough
Implementation Method 2
The resulting excitation of the rotor windings may produce a magnetic field operable with a stator generated electric field to create an output torque
Data Source
AI summary
A rotor power transfer circuit for an electric machine. The rotor power transfer circuit may include a multiple leaf direct current (DC)-to-DC (DC-DC) converter having a plurality of branches connected in parallel to a source of DC power. The branches may include a plurality of switches operable for selectively controlling DC power transfer therethrough according to a plurality of rotor winding excitations modes. The rotor power transfer circuit may include an electrical interface configured for electrically connecting each branch with one of a one or more rotor windings wrapped around a plurality of circumferentially spaced rotor protrusions of the electric machine.