US-12620868-B2 - Transverse pseudo direct drive

US12620868B2US 12620868 B2US12620868 B2US 12620868B2US-12620868-B2

Abstract

A magnetic gear assembly includes a first magnet ring comprising first magnetic pole-pairs disposed evenly along the first magnet ring, a second magnet ring comprising second magnetic pole-pairs disposed evenly along the second magnet ring, a third magnet ring comprising third magnetic pole-pairs disposed evenly along the third magnet ring, wherein each of the first magnetic pole-pairs, the second magnetic pole-pairs, and the third magnetic pole-pairs comprises two opposing magnets, and a fourth ring comprising ferromagnetic pieces disposed evenly along the fourth ring. The first, second, third, and fourth magnet rings are arranged along an axis, wherein the first and the second magnet rings are positioned on either side of the third magnet ring along the axis, and wherein magnetic flux generated by the third magnet ring is distributed between the first and the second magnet rings during operation of the magnetic gear assembly.

Inventors

Matthew Penne
Liyan Qu

Assignees

NUTECH VENTURES, INC.

Dates

Publication Date: 20260505
Application Date: 20231023

Claims (20)

1 . A magnetic gear assembly, comprising: a first magnet ring comprising first magnetic pole-pairs disposed evenly along the first magnet ring; a second magnet ring comprising second magnetic pole-pairs disposed evenly along the second magnet ring; a third magnet ring comprising third magnetic pole-pairs disposed evenly along the third magnet ring, wherein each of the first magnetic pole-pairs, the second magnetic pole-pairs, and the third magnetic pole-pairs comprises two opposing magnets; and a fourth ring comprising a plurality of ferromagnetic pieces disposed evenly along the fourth ring and separated by gaps, wherein the first magnet ring, the second magnet ring, the third magnet ring, and the fourth ring are arranged along an axis, wherein the first magnet ring and the second magnet ring are positioned on either side of the third magnet ring along the axis, and wherein magnetic flux generated by the third magnet ring is distributed between the first magnet ring and the second magnet ring during operation of the magnetic gear assembly.
2 . The magnetic gear assembly according to claim 1 , wherein the number of the first magnetic pole-pairs is the same as the number of the second magnetic pole-pairs, and wherein the number of third magnetic pole-pairs differs from the number of the first magnetic pole-pairs and the number of the second magnetic pole-pairs.
3 . The magnetic gear assembly according to claim 1 , wherein the number of the ferromagnetic pieces are determined based on the number of the first magnetic pole-pairs and the number of the third magnetic pole-pairs.
4 . The magnetic gear assembly according to claim 1 , wherein the third magnet ring and the fourth ring are arranged coaxially with respect to the axis, and the fourth ring is greater in axial length than the third magnet ring.
5 . The magnetic gear assembly according to claim 4 , wherein the axial length of the fourth ring is the sum of the axial lengths of the first magnet ring, the second magnet ring, the third magnet ring, a first air gap between the first magnet ring and the third magnet ring, and a second air gap between the second magnet ring and the third magnet ring.
6 . The magnetic gear assembly according to claim 1 , wherein the number of the first magnetic pole-pairs is greater than the number of the third magnetic pole-pairs.
7 . The magnetic gear assembly according to claim 1 , wherein the number of the first magnetic pole-pairs is smaller than the number of the third magnetic pole-pairs.
8 . The magnetic gear assembly according to claim 1 , wherein the ferromagnetic pieces in the fourth ring are made of ferromagnetic composites.
9 . The magnetic gear assembly according to claim 1 , wherein the first magnet ring and the second magnet ring are fixed with respect to the axis.
10 . The magnetic gear assembly according to claim 9 , wherein the magnetic gear assembly is assembled in an electrical generator, and wherein a plurality of stator windings are affixed outside the third magnet ring.
11 . The magnetic gear assembly according to claim 1 , wherein the third magnet ring is fixed with respect to the axis.
12 . The magnetic gear assembly according to claim 11 , wherein the magnetic gear assembly is assembled in an electrical generator, and wherein a plurality of stator windings are affixed outside the first magnet ring or the second magnet ring.
13 . The magnetic gear assembly according to claim 1 , wherein the magnetic gear assembly is assembled in a wind turbine, and wherein the fourth ring is connected to one end of a shaft in the wind turbine, and the other end of the shaft is connected to rotor blades of the wind turbine.
14 . The magnetic gear assembly according to claim 1 , further comprising: a fifth magnetic ring comprising fifth magnetic pole-pairs disposed evenly along the fifth magnet ring; and a sixth magnetic ring comprising sixth magnetic pole-pairs disposed evenly along the sixth magnet ring; wherein each of the fifth magnetic pole-pairs and the sixth magnetic pole-pairs comprises two opposing magnets, wherein the number of the fifth magnetic pole-pairs is the same as the number of the third magnetic pole-pairs, and the number of the sixth magnetic pole-pairs is the same as the number of the second magnetic pole-pairs; and wherein the magnetic rings are arranged in an alternating manner according to the number of magnetic pole-pairs comprised in the respective magnet rings.
15 . A motor comprising a magnetic gear assembly according to claim 14 .
16 . A motor comprising a magnetic gear assembly according to claim 1 .
17 . A wind turbine including a magnetic gear assembly according to claim 1 , wherein the fourth ring is connected to one end of a shaft in the wind turbine, and the other end of the shaft is connected to rotor blades of the wind turbine.
18 . An electrical generator comprising: a magnetic gear assembly, comprising: a first magnet ring comprising first magnetic pole-pairs disposed evenly along the first magnet ring; a second magnet ring comprising second magnetic pole-pairs disposed evenly along the second magnet ring; a third magnet ring comprising third magnetic pole-pairs disposed evenly along the third magnet ring, wherein each of the first magnetic pole-pairs, the second magnetic pole-pairs, and the third magnetic pole-pairs comprises two opposing magnets; and a fourth ring comprising ferromagnetic pieces disposed evenly along the fourth ring, wherein the first magnet ring, the second magnet ring, the third magnet ring, and the fourth ring are arranged along an axis, wherein the first magnet ring and the second magnet ring are positioned on either side of the third magnet ring along the axis, wherein magnetic flux generated by the third magnet ring is distributed between the first magnet ring and the second magnet ring during operation of the magnetic gear assembly, and wherein the first magnet ring and the second magnet ring are fixed with respect to the axis, and a plurality of stator windings affixed outside the third magnet ring.
19 . A magnetic gear assembly, comprising: a first magnet ring comprising first magnetic pole-pairs disposed evenly along the first magnet ring; a second magnet ring comprising second magnetic pole-pairs disposed evenly along the second magnet ring; a third magnet ring comprising third magnetic pole-pairs disposed evenly along the third magnet ring, wherein each of the first magnetic pole-pairs, the second magnetic pole-pairs, and the third magnetic pole-pairs comprises two opposing magnets; and a fourth ring comprising ferromagnetic pieces disposed evenly along the fourth ring, wherein the first magnet ring, the second magnet ring, the third magnet ring, and the fourth ring are arranged along an axis, wherein the first magnet ring and the second magnet ring are positioned on either side of the third magnet ring along the axis, wherein magnetic flux generated by the third magnet ring is distributed between the first magnet ring and the second magnet ring during operation of the magnetic gear assembly, and wherein the third magnet ring and the fourth ring are arranged coaxially with respect to the axis, and the fourth ring is greater in axial length than the third magnet ring.
20 . The magnetic gear assembly according to claim 19 , wherein the number of the first magnetic pole-pairs is the same as the number of the second magnetic pole-pairs, and wherein the number of third magnetic pole-pairs differs from the number of the first magnetic pole-pairs and the number of the second magnetic pole-pairs.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Patent Application No. 63/380,800, filed Oct. 25, 2022, titled “TRANSVERSE PSEUDO DIRECT DRIVE,” which is incorporated herein by reference in its entirety. BACKGROUND The present disclosure provides magnetic gears, and in particular symmetric transverse-flux magnetic gears, useful in direct drive systems. The first pseudo direct drive (PDD) was proposed in K. Atallah, J. Rens, S. Mezani, and D. Howe, “A novel “pseudo” direct-drive brushless permanent magnet machine,” IEEE Trans. on Magnetics, vol. 44, no. 11, pp. 4349-4352, November 2008 (hereinafter “Atallah-1”), which combined the coaxial radial-flux magnetic gear proposed in K. Atallah and D. Howe, “A novel high-performance magnetic gear,” IEEE Trans. on Magnetics, vol. 37, no. 4, pp. 2844-2846, July 2001, and a permanent magnet brushless machine. Coaxial magnetic gears are a method of torque transfer between two shafts rotating at different speeds. They are attractive over conventional mechanical gears because the rotating shafts have no mechanical connection and all torque is transferred magnetically. This results in less wear from friction, increased efficiency, increased reliability, and inherent overload protection [See, e.g., Y. Chen, W. N. Fu, S. L. Ho, and H. Liu, “A quantitative comparison analysis of radial-flux, transverse-flux, and axial-flux magnetic gears,” IEEE Trans. on Magnetics, vol. 50, no. 11, pp. 1-4, November 2014; K. Li and J. Z. Bird, “A review of the volumetric torque density of rotary magnetic gear designs,” in Proc. XIII International Conference on Electrical Machines (ICEM), October 2018, pp. 2016-2022; and C. G. C. Neves, A. F. Flores Filho, and D. G. Dorrel, “Design of a pseudo direct drive for wind power applications,” International Conference of Asian Union of Magnetics Societies (ICAUMS), pp. 1-5, August 2016]. This technology is extremely promising for wind energy, especially offshore wind energy, where maintaining or replacing the wind turbines' gearbox is prohibitively expensive. Coaxial magnetic gears can be as compact and cost effective as mechanical gears for a given application, but a stator can be incorporated in the design to produce a compact, low-cost electric machine. For low-speed applications, PDDs show promise over mechanically geared counterparts. They are estimated to have reduced size, weight, and cost over a mechanically geared high speed permanent magnet synchronous machine (PMSM) or a large direct drive PMSM [see, e.g., M. Bouheraoua, J. Wang, and K. Atallah, “Speed control for a pseudo direct drive permanent-magnet machine with one position sensor on low-speed rotor,” IEEE Trans. on Industry Applications, vol. 50, no. 6, pp. 3825-3833, November-December 2014]. In Atallah-1, the PDD design employs a radial-flux magnetic gear, with a stationary high pole-pair magnet ring on the outside, a high-speed low pole-pair magnet rotor spinning freely in the middle, and low-speed output/input rotor with ferromagnetic pole pieces rotating between the two magnet rings. A stator is affixed outside the high pole-pair magnetic ring, and the rotating magnetic field generated by the stator winding couples with the inner high-speed rotor to produce an electromagnetic torque. This electromagnetic torque couples with the ferromagnetic pole pieces in the low-speed rotor to induce a low-speed high torque output for motors or input for generators. This results in a compact low speed machine capable of handling large torques [see, Atallah-1]. Speed control of a PDD was derived in M. B. Kouhshahi et al., “An axial flux focusing magnetically geared generator for low input speed applications,” IEEE Trans. on Industry Applications, vol. 56, no. 1, pp. 138-147, January-February 2020. Problems with this design include the difficulty to cool the inner high-speed rotor and the fact that the high-speed rotor and the low-speed rotor need to be constructed with a bearing mechanically attaching the two. An alternative to the conventional radial-flux PDD is an axial-flux pseudo direct drive as in W. Bomela, J. Z. Bird, and V. M. Acharya, “The performance of a transverse flux magnetic gear,” IEEE Trans. on Magnetics, vol. 50, no. 1, pp. 1-4, January 2014. The axial-flux PDD uses a radial-flux stator to rotate the high-speed, low pole-pair magnet rotor directly. The magnet ring with high pole-pairs is stationary and placed axially to the high-speed rotor. A ring of steel pieces commutates the flux between the two rings of magnets and operates as the low-speed rotor. This design offers higher torque density than the radial-flux PDD, but at the cost of being mechanically complex, and a low-speed rotor that has high eddy current losses and can be difficult to manage heat. Thus, there is a need for developing techniques for use, among other applications, in low-speed pseudo direct drive applications. SUMMARY The systems and methods according to the prese