Passive magnetic bearing for low-speed flywheel energy storage system

Abstract

The invention relates to a passive magnetic bearing for a low-speed flywheel energy storage system. The passive magnetic bearing (6) consists of a static part and a rotating part, wherein the static part is fixed on the inner wall of a flywheel shell and consists of an upper magnetizer (1) and a permanent magnet; the upper magnetizer (1) has a concave structure; the permanent magnet is adhered tothe inner surface of the upper magnetizer (1); the thickness of the permanent magnet is equal to the depth of the concave of the upper magnetizer; the rotating part is arranged at the top end of a flywheel revolving shaft (5) and consists of a lower magnetizer (4) and a tightening screw; the lower magnetizer (4) is fixed at the top end of the flywheel revolving shaft (5); the upper magnetizer (1)and the lower magnetizer (4) are aligned; an adjustable air gap is formed between the static part and the rotating part of the passive magnetic bearing (6); and the lower magnetizer has a convex or disk structure. The magnetism generated by the permanent magnet is formed into a closure magnetic circuit by passing the upper magnetizer, the air gap and the lower magnetizer, axially generates attractive force and provides axial unloading force for the flywheel revolving shaft.

Description

Technical field [0001] The invention relates to a passive magnetic bearing, in particular to a passive magnetic bearing that provides an axial unloading force for a vertical low-speed flywheel energy storage system. Background technique [0002] Flywheel energy storage stores electrical energy in the form of mechanical energy in a high-speed rotating flywheel rotor, which is generally composed of the flywheel rotor, support bearings, motors, protective casings and external power conversion circuits. According to the operating speed of the flywheel rotor, it can be divided into a high-speed flywheel energy storage system and a low-speed flywheel energy storage system. The former uses composite material rotors and magnetic bearings, and the operating speed is tens of thousands of revolutions per minute; the latter uses metal material rotors and mechanical bearings , The working speed is generally several thousand revolutions per minute. [0003] In a vertical low-speed flywheel ener...

AI Technical Summary

Problems solved by technology

However, there are hidden dangers in the way of installing three permanent magnet rings on the electric spindle through the collar and the fixed ring. The maximum stress intensity of the permanent magnet is far less than the material of the electric spindle, and fragmentation may occur at high speeds.

Chinese invention patent CN101368595A proposes a passive magnetic bearing structure with large axial load capacity. This three-ring structure has a small magnetic flux leakage due to the closed magnetic circuit and a large axial load capacity. However, this structure has problems in the actual assembly process. certain degree of difficulty

US Patent 5894181 provides a passive magnetic bearing that can provide radial support and axial unloading at the same time, but this permanent magnet arrangement can only achieve the balance of the rotating shaft in a small range, which requires high machining accuracy. And the stiffness of the bearing system is small

[0005] Although the current relatively advanced technical solution is to combine passive magnetic bearings with superconducting bearings or electromagnetic bearings to realize the full magnetic levitation of the flywheel shaft and completely eliminate friction loss, such solutions are expensive in construction and maintenance and are not suitable for low-speed flywheel storage. energy system

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