Uncluttered Rotor Synchronous Machine Without Permanent Magnets
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Solution Overview
Problem
Permanent magnet machines face performance limitations due to centrifugal forces, flux leakages, limited power factor at slow speeds, operating temperature constraints, and high costs, especially at high speeds and temperatures.
Innovation Solution
A permanent magnet-less synchronous system with an uncluttered rotor and excitation coil that generates magnetic poles near the rotor's outer surface, interacting with stator currents to produce reluctance and magnet torques, reducing core losses and weight while allowing adjustable excitation fields for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are mounted near the outer circumference of the rotor to generate magnetic field, then motor performance is improved, but centrifugal force increases and causes flux leakages that decrease motor performance
Solution Approach 1:
The patent removes permanent magnets from the rotor structure entirely, extracting the source of centrifugal force and flux leakage problems. Instead of mounting magnets on the rotor, the invention uses a stator-based magnetic field generation system with no permanent magnets in the rotating assembly, thereby eliminating the harmful effects while maintaining motor function
Solution Approach 2:
The patent introduces an intermediary electromagnetic field generation method where stator windings create a rotating magnetic field that interacts with the rotor without requiring permanent magnets on the rotor. This intermediary approach allows magnetic field interaction necessary for motor operation while avoiding the direct placement of magnets that would suffer from centrifugal forces
2Strength
If stronger bridges are used to counter centrifugal force at high speeds, then rotor structural integrity is improved, but flux leakages increase which decreases motor performance
Solution Approach 1:
The patent eliminates the need for strong bridges by removing permanent magnets from the rotor entirely. Without magnets to secure, there are no centrifugal forces acting on rotor-mounted components, thus no need for reinforcing bridges that would cause flux leakage
Solution Approach 2:
The patent converts the harmful effect of centrifugal force on rotor-mounted magnets into a benefit by eliminating the magnets themselves. The design accepts that high-speed rotation creates centrifugal forces, but instead of fighting them with stronger structures that cause flux leakage, it removes the source of the problem entirely
3Power
If permanent magnets are used in the rotor, then magnet torque is generated, but operating temperature is limited as magnets become demagnetized at high temperatures
Solution Approach 1:
The patent replaces expensive, temperature-sensitive permanent magnets with a more robust electromagnetic field generation system using standard copper windings in the stator. These windings can operate at higher temperatures without demagnetization, effectively using a 'simpler' solution that withstands harsher thermal conditions
Solution Approach 2:
The patent changes the fundamental parameter of magnetic field generation from permanent magnets (which have fixed magnetic properties that degrade with temperature) to electromagnets in the stator (which can maintain field strength through controlled current). This parameter change allows operation across a wider temperature range without demagnetization concerns
4Power
If back electromotive force in stator winding is induced by permanent magnets, then magnet torque is produced, but motor speed is limited
Solution Approach 1:
The patent implements a dynamic magnetic field generation system where the stator windings create a rotating magnetic field that can be independently controlled in speed and strength. This dynamic approach allows the motor to operate at higher speeds without the back EMF limitations imposed by fixed permanent magnet fields, as the field strength can be adjusted to match speed requirements
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 solution achieves high power density, improved dynamic balance, optimized power factors, and reduced costs, enabling efficient operation across various applications and temperatures without the limitations of traditional permanent magnet machines.
Implementation Method 1
The excitation source generates a magnet torque by inducing magnetic poles near an outer peripheral surface of the uncluttered rotor, which interact with the stator currents
Implementation Method 2
A stator that generates a magnetic rotating field when sourced by an alternating current
Implementation Method 3
The stator currents also interact with the unequal magnetic paths along a direct axis and a quadrature axis of the rotor to produce a reluctance torque
Data Source
AI summary
A permanent magnet-less and brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by polyphase alternating currents. An uncluttered rotor is positioned within the magnetic rotating field and is spaced apart from the stator. An excitation core is spaced apart from the stator and the uncluttered rotor and magnetically couples the uncluttered rotor. The brushless excitation source generates a magnet torque by inducing magnetic poles near an outer peripheral surface of the uncluttered rotor, and the stator currents also generate a reluctance torque by a reaction of the difference between the direct and quadrature magnetic paths of the uncluttered rotor. The system can be used either as a motor or a generator