Consequent-Pole Rotor With Two-Layer Magnets for Higher Torque
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Solution Overview
Problem
Traditional consequent-pole motors have a small reluctance torque and limited electromagnetic torque due to the small thickness of permanent magnets in the d-axis magnetic circuit.
Innovation Solution
The motor design incorporates a rotor with permanent magnetic poles having multiple layers of permanent magnets, specifically a first and second layer permanent magnet, distributed evenly along the circumferential direction, which increases the reluctance torque and subsequently the electromagnetic torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional consequent-pole motor structure is used with single-layer permanent magnets, then the manufacturing complexity is reduced and the number of permanent magnets is minimized, but the reluctance torque is small and the electromagnetic torque is limited
Solution Approach 1:
The patent transitions from a single-layer permanent magnet structure to a multi-layer permanent magnet structure in the radial direction. This dimensional change allows magnetic flux to pass through multiple permanent magnets sequentially, increasing the equivalent magnetic path length and enhancing reluctance torque without significantly increasing overall device complexity
Solution Approach 2:
The patent employs nested permanent magnets where inner-layer and outer-layer permanent magnets are positioned concentrically. The magnetic flux from the stator passes through the outer-layer permanent magnet, then through the inner-layer permanent magnet, creating a nested magnetic circuit that multiplies the reluctance effect and increases electromagnetic torque
2Power
If the thickness of permanent magnets in d-axis magnetic circuit is increased to increase reluctance torque, then the electromagnetic torque increases, but the motor size and volume increase
Solution Approach 1:
Instead of increasing permanent magnet thickness in the radial direction (which would increase motor volume), the patent utilizes the circumferential dimension by arranging multiple permanent magnets in series along the magnetic flux path. This allows the magnetic flux to traverse multiple thinner permanent magnets, achieving increased reluctance torque without proportionally increasing the motor's radial dimensions
Solution Approach 2:
The patent divides the permanent magnet structure into multiple segments (inner-layer and outer-layer permanent magnets) that are distributed along the circumferential direction. This segmentation allows the total magnetic path length to be extended through multiple discrete permanent magnets rather than requiring a single thick permanent magnet, thereby increasing reluctance torque while controlling overall 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
The use of multiple layers of permanent magnets enhances the q-axis inductance, increases the difference in inductances between the q-axis and d-axis, and effectively boosts the reluctance torque, leading to an increase in electromagnetic torque.
Implementation Method 1
A permanent magnet of the rotor includes an inner permanent magnet and an outer permanent magnet. The outer permanent magnet and the inner permanent magnet are disposed at different radii of the rotor. The magnetic lines of the outer permanent magnet and the inner permanent magnet are substantially overlapped.
Implementation Method 2
adjacent permanent magnets have different magnetization directions. A consequent-pole permanent magnet synchronous motor has only four permanent magnets, which are equally distributed along a circumference, and adjacent permanent magnets have the same length in their magnetization directions.
Implementation Method 3
A soft magnetic material between two permanent magnet mounting grooves is magnetized by the permanent magnetic pole to have an opposite polarity to the permanent magnetic pole, so it is called a consequent-pole permanent magnet motor.
Data Source
AI summary
A consequent-pole motor comprises a rotor and a stator sleeved outside the rotor. The rotor comprises a plurality of permanent magnetic poles evenly spaced along a circumferential direction of the rotor. A plurality of stator teeth is disposed on an inner periphery of the stator along a circumferential direction of the inner periphery. A permanent magnetic pole of the rotor comprises a first permanent magnet mounting groove and a second permanent magnet mounting groove disposed sequentially from outside to inside along a radial direction of the rotor. A first layer permanent magnet is disposed in the first permanent magnet mounting groove, and a second layer permanent magnet is disposed in the second permanent magnet mounting groove. According to the motor, permanent magnets distributed in multiple layers are used, so that the magnetic resistance torque of the motor can be improved, which may increase reluctance torque, thereby increasing electromagnetic torque.