Motor Generator Air Gap Flux Alignment to Reduce Hysteresis Loss
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Solution Overview
Problem
Conventional motors and generators experience high hysteresis losses due to non-optimized magnetic flux alignment, particularly at maximum torque conditions where the flux crosses the air gap at an angle of approximately 45 degrees, leading to uneven flux distribution and inefficient use of iron core materials.
Innovation Solution
The solution involves maintaining continuity of flux direction between the stator, air gap, and rotor, using uni-directionally tapered stator slots and magnet segments with optimized magnetization to achieve uniform flux density, along with the use of DC excitation and permanent magnets, and adjustable conductor cross-sections to minimize hysteresis losses and optimize iron and copper usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial flux paths are used in the iron core between coil slots, then good alignment of magnetic flux in the iron and air gap is achieved under no-load zero-torque conditions, but high hysteresis losses occur at maximum torque conditions when flux crosses the air gap at approximately 45 degrees
Solution Approach 1:
The patent applies the dynamics principle by making the stator slots tapered rather than parallel-sided, allowing the flux path geometry to adapt dynamically to different operating conditions. The tapered slots guide the flux at approximately 45-degree angles during maximum torque operation, optimizing flux distribution and reducing hysteresis losses while maintaining acceptable alignment under no-load conditions.
Solution Approach 2:
The patent changes the geometric parameters of the stator slots from parallel-sided to tapered, with specific taper angles designed to optimize flux distribution. This parameter change allows the flux paths to better align with the tapered slot geometry during high-torque operation, reducing the uneven flux density that causes high hysteresis losses.
2Power
If flux crosses the air gap at an angle of approximately 45 degrees for maximum torque, then torque output is maximized, but flux distribution in the radial stator tooth becomes very uneven resulting in high hysteresis losses
Solution Approach 1:
The patent applies local quality by creating non-uniform flux distribution within the stator teeth through tapered slot geometry. The taper angles are specifically designed to concentrate flux in certain regions and reduce it in others, optimizing the overall flux distribution pattern to reduce hysteresis losses while maintaining the 45-degree crossing angle for maximum torque.
Solution Approach 2:
The patent introduces asymmetry through the tapered slot design, where the slot width varies along its length rather than remaining constant. This asymmetric geometry is designed to compensate for the uneven flux distribution that occurs during high-torque operation, creating a more uniform overall flux density pattern that reduces hysteresis losses.
3Ease of manufacture
If conventional parallel-sided stator slots are used, then manufacturing is simplified, but iron core materials are used inefficiently with low flux areas representing wasted space that could be used for larger lower-loss conductors
Solution Approach 1:
The patent changes the geometric parameters of the stator slots from uniform width to tapered width, with the taper angle optimized to match the flux distribution pattern during maximum torque operation. This parameter change improves material utilization by ensuring that iron is present in regions where flux density is high, eliminating the wasted material in low-flux regions that occurs with parallel-sided slots.
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 results in reduced hysteresis losses, more efficient use of iron core materials, and improved overall efficiency, allowing for larger cross-section coils and enhanced power factor control.
Implementation Method 1
The present invention reduces hysteresis losses in the iron of motors and generators by means of improved alignment of the magnetic flux paths in the rotor and stator with the magnetic flux orientation in the air gap
Implementation Method 2
The present invention reduces hysteresis losses in the iron of motors and generators
Implementation Method 3
DC excitation current is provided to auxiliary DC windings in the stator. This results in a non-rotating magnetic field that passes in and out of the rotor where it generates AC excitation power
Implementation Method 4
Once in place a stretchable elastomeric shim may be inserted while in the stretched and thin state. This may be inserted while attached to a tensioned cord, for example. Once it is in the correct axial position, the tension may be reduced, allowing the elastomeric shim to shorten and expand laterally
Data Source
AI summary
The present inventions include a rotating electromagnetic machine such as a motor or generator wherein changes of flux direction adjacent the air gap are avoided. The disclosed improvements apply to permanent magnet alternators, induction motors and generators, doubly fed induction generators, and the like. Adaptation of coils to and fixation within the required slot geometries are disclosed. Excitation systems co-located within the primary rotor core and primary stator core are also disclosed. The use of rubber vulcanized to the rotor in conjunction with a stainless steel rotor sleeve is also disclosed.