Parallel Magnetic Circuit Motor Stator Design
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Solution Overview
Problem
Traditional permanent magnet (PM) machines face limitations in power density, efficiency, and reliability due to the fixed energy product of permanent magnets, inability to achieve high gap flux densities, structural issues, sensitivity to temperature, and uncontrolled fringing flux, which restrict their performance and controllability compared to wound field machines.
Innovation Solution
A parallel magnetic circuit motor design featuring a rotor without magnets and a stator with magnets, utilizing a geometry that allows for unidirectional current and torque with electrically independent phases, enabling increased power density, efficiency, and reliability by redirecting the static field without opposing forces and mitigating bonding issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If permanent magnets are used to replace field coils, then machine size and weight are reduced and I2R losses are eliminated, but controllability of the static magnetic field is limited and gap flux density cannot achieve the levels of wound field machines
Solution Approach 1:
The stator is divided into multiple independent magnetic circuits, each with its own permanent magnets and windings. This segmentation allows independent control of each magnetic circuit while maintaining the weight and efficiency benefits of permanent magnets, thereby improving controllability without sacrificing the advantages of PM machines.
Solution Approach 2:
The invention introduces dynamic controllability to the static magnetic field produced by permanent magnets through controlled winding excitation. By dynamically adjusting the winding currents in each magnetic circuit, the static field can be modulated and controlled, transforming the inherently static PM field into a controllable field while retaining the benefits of permanent magnets.
2Loss of energy
If permanent magnets are used to replace field coils, then I2R losses are eliminated and efficiency is improved, but the energy product of permanent magnets is fixed limiting the magnitude of the static field
Solution Approach 1:
The invention merges the advantages of both permanent magnets and wound field coils by combining permanent magnets with controllable windings in each magnetic circuit. This hybrid approach eliminates I2R losses in the field coils while allowing the static field magnitude to be controlled and adjusted, achieving both high efficiency and high power capability.
Solution Approach 2:
The magnetic circuit uses a composite structure combining permanent magnet materials with magnetically soft core materials. This composite approach allows the system to benefit from the high energy product of permanent magnets while utilizing the controllable magnetic properties of the soft core materials to adjust and optimize the static field magnitude, achieving both efficiency and power density.
3Volume of moving object
If permanent magnets are placed on the rotor, then machine size and weight are reduced, but bonding issues are created and structural integrity is compromised
Solution Approach 1:
The invention inverts the conventional arrangement by placing permanent magnets on the stator instead of the rotor. This reversal eliminates the bonding and structural integrity issues associated with mounting magnets on the rotating rotor, while still achieving the space and weight savings of permanent magnet machines. The stator-mounted magnets provide a stable, vibration-free configuration.
4Volume of moving object
If permanent magnets are used, then machine size is reduced, but sensitivity to temperature increases
Solution Approach 1:
The magnetically soft core materials serve as intermediaries between the permanent magnets and the air gap. These soft core materials have favorable temperature characteristics that compensate for the temperature sensitivity of the permanent magnets, acting as a buffer that stabilizes the overall magnetic circuit performance across a wide temperature range while maintaining the compact size benefits of PM machines.
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 PMC motor achieves higher efficiency and power density over a wider range, with rectangular power output curves and higher air gap flux densities, outperforming conventional PM machines by eliminating repelling fields and reducing weight and I2R losses, while maintaining the benefits of permanent magnets.
Implementation Method 1
The rotor, stator and windings are configured to produce unidirectional current and torque with electrically independent phases
Implementation Method 2
A parallel magnetic circuit motor has a rotor without magnets and a stator with magnets
Data Source
AI summary
A parallel magnetic circuit motor includes a rotor without magnets and a stator with magnets. The stator has stator poles with windings. The windings are energized on a first plurality of stator poles with current in a same first direction and the windings are energized on a second plurality of stator poles with current in a same second direction opposite the same first direction.