Active magnetic bearing using bias magnetic flux commonly in radial direction and in axial direction and control method thereof

Abstract

The invention relates to an active magnetic bearing using a bias magnetic flux commonly in radial direction and in axial direction. A bias magnetic current in an axial control coil provides a static bias magnetic flux for the radial direction and the axial direction to generate static bearing capacity, the control current in the axial control coil and in a radial control coil provides the controlmagnetic flux to respectively generate dynamic levitation force in radial direction and in axial direction, and external disturbance is overcome to ensure that a rotor levitates stably at a balance position of the radial direction and the axial direction. A bipolarity switch power amplifier is adopted in axial direction, a CRPWM current following inverter is adopted as a power amplification circuit in radial direction, an eddy current displacement transducer is adopted to detect axial displacement and radial displacement of the rotor and feed the axial displacement and radial displacement backto a DSP controller which is used for carrying out PID operation and providing a corresponding control signal for the power amplification circuit after processing, and the power amplification circuitgenerates control current in a magnetic bearing coil to realize stable levitation of the rotor in axial direction and in redial direction. The active magnetic bearing of the invention has the advantages of small volume, low power amplifier cost and high radial bearing capacity.

Description

technical field [0001] The invention belongs to the technical field of electrical transmission (mechanical transmission) equipment, and is a new type of high-performance bearing without mechanical contact, especially a new type of radial-axial shared bias magnetic bearing integrating radial and axial functions. Tong's active magnetic bearings can be used as non-contact suspension supports for rotating parts in mechanical equipment such as five-degree-of-freedom magnetic levitation high-speed machine tool electric spindle systems. Background technique [0002] Since the rapid development of magnetic bearing technology in the 1970s, magnetic bearing researchers at home and abroad have focused on the study of active axial single-degree-of-freedom and radial two-degree-of-freedom magnetic bearings, and the main method of magnetic bearing control is DC. The signal provides both static bias flux and control flux. To achieve stable suspension of the rotor, control force needs to b...

AI Technical Summary

Problems solved by technology

The axial length of the mechanical structure of the 5-DOF magnetic bearing supporting the high-speed motor is relatively long, which has certain restrictions on the increase of the critical speed of the rotor, and a radial magnetic bearing needs two bipolar power amplifiers to drive, and the power amplifier is large in size, High power consumption and high cost, therefore, this magnetic bearing supported high-speed motor structure limits its practical application range in engineering

[0003] At the Seventh International Conference on Magnetic Bearings, C. Redemann of the Swiss Federal Institute of Technology (ETH) in Zurich published a test report on the application of a 30kW bearingless sealed pump, and studied the AC hybrid magnetic bearing with two degrees of freedom in the radial direction. The three-phase inverter commonly used in the industry is directly used to provide the control current, and the permanent magnet is used to provide the static bias magnetic field, which greatly reduces the size of the power amplifier and reduces the rotation loss, but it still needs to be realized with an axial magnetic bearing. The three-degree-of-freedom suspension support still fails to make progress in the compact axial structure of the overall system and the increase in the critical speed of the rotor

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