Arc-Slit Synchronous Reluctance Rotor for Low Torque Ripple
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Solution Overview
Problem
Conventional synchronous reluctance motors face challenges in achieving both high output torque and reduced torque ripple due to the limitations of slit interval design, which are not effectively addressed by existing methods that prioritize either output torque or torque ripple reduction.
Innovation Solution
The design incorporates an annular stator core with slots at equal intervals and a cylindrical rotor core with arc-shaped slits, where the slit intervals are optimized to fall within a specific range (360/(2×P×z)<θ<360/(P×z) to balance output torque and torque ripple, and the slit shapes are defined by specific arc dimensions and ratios to enhance magnetic flux passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of slits is increased and saliency ratio is increased to increase output torque, then output torque is improved, but torque ripple increases due to sharp change in permeance in the vicinity of the slit
Solution Approach 1:
The slits are designed with arc-shaped openings that are convex toward the cylinder center, replacing straight or conventional slit shapes. This curved geometry modifies the magnetic flux distribution and reduces the sharp permeance changes that cause torque ripple, while still maintaining the saliency effect needed for high output torque.
Solution Approach 2:
The invention optimizes specific geometric parameters of the slits including the arc radius R, the distance D from the outer circumferential surface to the arc center point, and the ratio k=D/R. By carefully controlling these parameters within specific ranges, the motor achieves both high output torque and reduced torque ripple.
2Object-generated harmful factors
If slits are arranged at narrow intervals to reduce torque ripple by suppressing harmonic components, then torque ripple is reduced, but output torque decreases due to reduced saliency ratio
Solution Approach 1:
The arc-shaped slit configuration changes the magnetic circuit characteristics, allowing for effective torque ripple suppression even with wider slit intervals, thereby maintaining the saliency ratio and output torque.
Solution Approach 2:
By optimizing the slit interval θ within the specific range and adjusting the arc geometry parameters, the invention achieves a balance where torque ripple is reduced without significantly compromising the saliency ratio and output torque.
3Object-generated harmful factors
If slits are arranged at equal angular intervals to reduce torque ripple, then torque ripple is reduced, but output torque is not maximized due to inadequate consideration of magnitude of output torque
Solution Approach 1:
The invention provides specific quantitative ranges for the slit interval θ (360/(2×P×z) < θ < 360/(P×z)) and arc geometry parameters (ratio k=D/R, distance D, radius R) that simultaneously optimize both torque ripple reduction and output torque magnitude, going beyond the generic equal-interval approach.
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 configuration effectively suppresses torque ripple and increases output torque by ensuring the slit intervals do not coincide with the stator slot intervals, thereby enhancing the inductance difference between the d-axis and q-axis, leading to improved motor performance.
Implementation Method 1
The synchronous reluctance motor has a slit in a rotor to generate magnetic saliency, and rotates with reluctance torque generated by the magnetic saliency
Implementation Method 2
rotates with reluctance torque generated by the magnetic saliency
Data Source
AI summary
The synchronous reluctance motor includes: an annular stator core having slots; and a cylindrical rotor core-having, for each magnetic pole, slits formed by arc-shaped openings which are convex toward a cylinder center and whose apexes are positioned on a q axis. The nth arc that is an inner edge of the opening close to the cylinder center has an arc center point on the q axis at a distance D(n) from-the rotor core. Where the radius of the nth arc with respect to the arc center point is denoted by R(n) and a ratio k(n) is defined as D(n)/R(n), the values of the ratios k(1) to k(n) are determined such that 0.20≤k(nmax)≤0.37 and k(nmax)< . . . <k(n)< . . . <k(1)<1 are satisfied and a slope a is in a range of (−0.92/nmax)≤a≤(−0.71/nmax).