Dual-Armature Flux-Switching Machine for Higher Torque Density
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Solution Overview
Problem
Conventional flux-switching electrically excited machines suffer from low torque density due to weak magnetic fields from DC field windings, increased electrical and thermal loads, and poor fault-tolerance of stator windings, leading to complex control strategies and high costs.
Innovation Solution
A dual-armature flux-switching electrically excited machine with specific stator and rotor configurations, including parallel and non-parallel stator slots, and coordinated current phase angles for stator and rotor armature windings, to enhance torque density and fault-tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC field windings are used to generate magnetic field in flux-switching electrically excited machines, then the machine can operate without permanent magnets, but the magnetic field strength is much weaker than that provided by permanent magnets, leading to low torque density
Solution Approach 1:
The patent merges two armature windings (stator armature winding and rotor armature winding) with the field winding system to create a combined magnetic field that is significantly stronger than conventional DC field windings alone, thereby achieving high torque density without permanent magnets
Solution Approach 2:
The patent employs dynamic control of the dual armature windings where the stator armature winding current phase angle is controlled at 0° to 90° and the rotor armature winding current phase angle is controlled at -90° to 0°, enabling dynamic optimization of the magnetic field strength and torque output
2Power
If exciting currents or number of turns of DC field windings are increased to enhance magnetic field, then the magnetic field strength is improved, but the electrical load and thermal load are significantly increased, making insulation design and cooling management extremely difficult
Solution Approach 1:
The patent segments the magnetic field generation function across three separate winding systems (field windings, stator armature windings, and rotor armature windings), distributing the electrical and thermal loads across multiple components rather than concentrating them in a single DC field winding system
Solution Approach 2:
The patent introduces a spatial dimension by adding rotor armature windings to the conventional stator-based system, creating a three-dimensional distribution of windings (stator field, stator armature, rotor armature) that spreads thermal generation throughout the machine volume, facilitating heat dissipation
3Reliability
If stator DC field windings and stator armature windings are designed with redundancy to guarantee fault-tolerant operation, then certain degree of fault-tolerant operation is achieved, but properties such as torque output, efficiency, and operational stability deteriorate seriously, accompanied by unbalanced forces and increased local eddy-current losses
Solution Approach 1:
The patent designs the rotor armature windings to serve multiple functions: they generate torque during normal operation and simultaneously serve as a backup field excitation system during fault conditions, eliminating the need for separate redundant windings and maintaining torque output during faults
Solution Approach 2:
The rotor armature windings are designed to automatically assume the role of field windings when the conventional field windings fail, enabling the machine to self-maintain operation without external intervention or complex control switching
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 machine achieves improved torque density and fault-tolerant operation by distributing copper losses uniformly, maintaining torque output without winding failures, and simplifying control strategies.
Implementation Method 1
the permanent magnets are replaced with DC field winding
Implementation Method 2
the stator armature windings and the rotor armature windings are fed with an alternating current
Data Source
AI summary
The present disclosure relates to a dual-armature flux-switching electrically excited machine, including a stator and a rotor. The stator includes a stator core, field windings, and stator armature windings. The rotor includes rotor armature windings. When the windings are in a working state, the field windings are fed with a direct current, the stator armature windings and the rotor armature windings are fed with an alternating current, a current phase angle of the stator armature windings can be adjusted between 0° to 90°, and a current phase angle of each of the rotor armature windings can be adjusted between −90° to 0°. Through the dual-armature topology and the cooperation of the current phase angles of the armature windings, the torque density of the electrically excited machine is significantly improved.