Cogging Electric Machine Segment Phase Shift
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Solution Overview
Problem
Existing electric machines with permanent magnets suffer from parasitic cogging torque due to the interaction between permanent magnets and ferromagnetic teeth, which is difficult to eliminate without increasing the machine's volume, and existing methods for minimizing cogging torque are limited in effectiveness.
Innovation Solution
The cogging electric machine design features two identical segments with tooth coils aligned to match the number of rotor magnets, where the winding forms a single phase with phase-shifted currents, reducing torque variability and allowing the cogging torque to support working excitation torque within a specific range, thereby optimizing power-to-mass ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional methods (skewed grooves, magnet skews, or selective tooth/coil positioning) are used to minimize cogging torque, then cogging torque is reduced, but the machine volume increases and power-to-mass ratio deteriorates
Solution Approach 1:
The patent converts the harmful cogging torque into a beneficial component by positioning teeth and coils such that cogging torque supports excitation torque within a specific rotor position range, eliminating the need for traditional reduction methods that会增加 machine volume
Solution Approach 2:
The patent changes the positioning parameters of teeth and coils relative to each other, specifically positioning teeth at angles differing by more than 45 electrical degrees from adjacent teeth, and configuring coils to span across multiple teeth, thereby transforming the cogging torque characteristics from harmful to useful
2Object-generated harmful factors
If armature teeth are eliminated to reduce cogging torque, then cogging torque is minimized, but the machine volume increases due to alternative winding arrangements
Solution Approach 1:
The patent applies different functional characteristics to different parts of the magnetic circuit: teeth are positioned at specific angles with particular coil configurations, while other regions have different tooth-coil arrangements, allowing cogging torque to be harnessed in specific zones without increasing overall machine volume
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 design significantly reduces the aggregate variable torque components while maintaining a substantial constant torque, enabling the construction of electric machines with improved power-to-mass efficiency using fewer materials for the electrical and magnetic circuits.
Implementation Method 1
an electromagnetic torque, acting between the teeth of a ferromagnetic armature with tooth coils and the permanent magnets of an exciter
Implementation Method 2
The cogging torque occurs due to the cooperation of a magnetic field created by permanent magnets with the magnetic circuit of an armature
Implementation Method 3
an electromagnetic torque, acting between the teeth of a ferromagnetic armature with tooth coils and the permanent magnets of an exciter
Implementation Method 4
The cogging torque occurs due to the cooperation of a magnetic field created by permanent magnets with the magnetic circuit of an armature
Data Source
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AI summary
The object of the invention is a cogging electric machine and a method of operating the cogging electric machine. The machine is characterised in that the armature (1) comprises at least two constructionally identical segments (1A), (1B), each of which has tooth coils (2), shifted relative to the tooth coils of the other segment by a vector with the same direction as the direction of movement of the moving element of the machine, and a length resulting from the number of teeth (8). The number of teeth in each segment (1A), (1B) of the armature (1) is an even number equal to the number of magnets (5) of a single segment, while the winding of each segment forms a single phase intended for providing power with alternating current with a zero average value. The object of the invention constitutes a machine with rotary motion, in which the multi-segment armature (1) has the form of a stator, while the exciter comprises the magnets of rotor segments (4), the current of the armature (1) of each consecutive segment (1B) after the first one being phase-shifted relative to the current of the first segment by a value dependent on the length of the shifting vector of the coils (2), the spacing between the teeth (8) and the number of pairs of magnets (5) of a single rotor segment. It is also possible that the moving part constituting the rotor (4) is external relative to the immovable internal armature. The method of operating the electric machine is characterised in that, due to the phase shift of alternating currents flowing in the windings of the segments (1A), (1B), (1C) and the mechanical circumferential shift of the coils (2) in the windings of these segments, the aggregate variable component of the torques generated in the individual segments (1A), (1B), (1C) becomes reduced to a value resulting from the presence of harmonics of an order higher than the number of pole pairs in the gap field, while at the same time the constant components of the torques of the individual segments sum up.