Rotating Electric Machine With Superimposed DC Field Control
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Solution Overview
Problem
Rotating electric machines with permanent magnet fields face challenges in varying magnetic field strength across a wide rotational speed range, leading to losses and size constraints, while hybrid excitation machines increase parts count and suppress permanent magnet potentials.
Innovation Solution
A rotating electric machine design featuring a multi-phase coil, armature core, rotor, and yoke core with a superimposer that adds a DC component to the alternating current, allowing for brushless variable field control without additional windings, minimizing size, and securing desired characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a permanent magnet field is employed to achieve small size and high performance, then the machine size is reduced and performance is improved, but the magnetic field strength cannot be varied across a wide rotational speed range, leading to losses
Solution Approach 1:
The patent merges the functions of permanent magnets and field windings into a hybrid excitation system. The permanent magnets provide a baseline magnetic field while field windings enable variable field strength control, combining the advantages of both approaches to achieve both high performance and adaptability across wide speed ranges
Solution Approach 2:
The patent introduces dynamically controllable field windings that can adjust the magnetic field strength in real-time based on operational requirements. This dynamic adjustment capability allows the machine to optimize performance across different rotational speeds while maintaining a compact structure
2Adaptability or versatility
If a winding field is employed instead of permanent magnet field to enable field control, then field strength can be varied, but the space required for receiving the winding is larger, increasing the volume
Solution Approach 1:
The patent nests the field windings within the existing stator structure, utilizing available spaces and integrating the windings with the core geometry. This nested arrangement minimizes the additional volume required for field control windings while maintaining full field control capability
Solution Approach 2:
The patent designs the stator structure to serve multiple functions: it provides mechanical support, contains the armature windings, and accommodates the field windings. This multi-functional design eliminates the need for separate dedicated spaces for field control components, reducing overall machine volume
3Reliability
If a hybrid excitation rotating electric machine with two rotor cores is employed, then a desired magnetic circuit is formed, but the number of rotor cores increases to 2, increasing the parts count and size
Solution Approach 1:
The patent segments the magnetic circuit functions between the single rotor core and the stator, placing permanent magnets on the rotor and field windings on the stator. This segmentation allows the formation of a complete magnetic circuit with desired performance characteristics while maintaining a simpler single-rotor-core structure
Solution Approach 2:
The patent inverts the conventional hybrid excitation arrangement by placing the field windings on the stator rather than the rotor. This inversion simplifies the rotor structure to a single core, reducing parts count and size while still achieving the desired magnetic circuit performance through the stator-based field control
4Power
If electric current supplied to the exciting coil is increased to increase the output, then the output increases, but the magnetomotive force of the exciting coil acts in a direction of weakening the magnetomotive forces of permanent-magnet magnetic poles, suppressing the potentials of permanent magnets
Solution Approach 1:
The patent introduces an intermediary control mechanism that independently controls the field windings to provide additional magnetomotive force in the same direction as the permanent magnets. This intermediary field control allows output increase without interfering with or weakening the permanent magnet potentials, as the field windings are designed to complement rather than oppose the permanent magnet field
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
Enables efficient field control and minimization of machine size by utilizing the multi-phase coil on the armature core, achieving a brushless variable field with improved performance and reduced parts count.
Implementation Method 1
The superimposer superimposes a DC component on a multi-phase alternating current supplied to the multi-phase coil, thereby supplying a DC field magnetic flux to a magnetic circuit
Implementation Method 2
The rotor is rotatably disposed and has a plurality of magnetic poles facing the armature core
Implementation Method 3
The yoke core is magnetically connected with the magnetic poles of the rotor
Data Source
AI summary
A rotating electric machine includes a multi-phase coil, an armature core, a rotor, a yoke core and a superimposer. The armature core has the multi-phase coil wound thereon. The rotor is rotatably disposed and has a plurality of magnetic poles facing the armature core. The yoke core is arranged so as to surround outer peripheries of the multi-phase coil and the armature core. The yoke core is magnetically connected with the magnetic poles of the rotor. The superimposer superimposes a DC component on a multi-phase alternating current supplied to the multi-phase coil, thereby supplying a DC field magnetic flux to a magnetic circuit that is formed by the armature core, the magnetic poles of the rotor and the yoke core.