A four-degree-of-freedom radial vibration suppression strategy

Abstract

The present invention discloses a four-degree-of-freedom radial vibration suppression strategy, belonging to the technical field of four-degree-of-freedom suspension system control technology. By adding two vibration acceleration sensors placed at 90 degrees orthogonal to the motor housing, vibration accelerations in two orthogonal directions can be obtained, thereby determining the eccentricity of the rotating shaft for subsequent control. The four-degree-of-freedom vibration suppression strategy proposed in the present invention only requires the installation of two orthogonally placed vibration acceleration sensors to achieve closed-loop control, and has the advantages of simple structure and high reliability. In addition, the use of a bearingless motor and a coordinated radial force control method of two radial magnetic bearings makes the vibration reduction effect more prominent.

Description

Technical Field

[0001] The invention relates to a four-degree-of-freedom radial vibration suppression strategy, belonging to the technical field of four-degree-of-freedom suspension system control. Background Art

[0002] As motor power increases, traditional mechanical bearings are no longer suitable for high-speed, high-power motor applications, resulting in severe bearing wear. To address this, the original mechanical bearings were eliminated and two radial magnetic bearings were added to the original shaft, giving the traditional motor four-degree-of-freedom suspension capabilities. However, traditional four-degree-of-freedom suspension systems can only suppress vibration forces at the magnetic bearings, but cannot eliminate vibration at the motor. By adopting bearingless motor technology and adding a set of suspension windings to the motor stator, the motor also has radial force control capabilities, further reducing system vibration.

[0003] However, when both the motor and the two radial magnetic bearings are equipped with active radial force control, coordination of these forces becomes crucial. Improper control can lead to increased housing vibration, increasing structural stress and compromising the stable operation of the suspension system. Therefore, minimizing shaft vibration is a pressing issue. Summary of the Invention

[0004] The present invention aims to propose a four-degree-of-freedom radial vibration suppression strategy, which adopts a radial force coordinated control method of a bearingless motor and two radial magnetic bearings, thereby reducing or even eliminating the system structure vibration.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] A four-degree-of-freedom radial vibration suppression strategy is applied to a four-degree-of-freedom suspension system. The four-degree-of-freedom suspension system includes a bearingless motor, a first radial magnetic bearing, a second radial magnetic bearing, a first vibration acceleration sensor, and a second vibration acceleration sensor. The first vibration acceleration sensor and the second vibration acceleration sensor are placed on the housing of the bearingless motor, including:

[0007] Step S1: The first vibration acceleration sensor and the second vibration acceleration sensor collect the vibration acceleration a of the housing of the bearingless motor in real time. x and vibration acceleration a y , after passing through the low-pass filter, the output vibration acceleration a x1 and vibration acceleration a y1 , and obtain the synthetic vibration acceleration a s ;

[0008] Step S2: According to the vibration force distribution characteristics of the housing, the vibration acceleration a is x, the vibration acceleration a y The LMS adaptive filtering algorithm is used to estimate the vibration force at the first radial magnetic bearing and the second radial magnetic bearing, and then the x-direction compensation current Δi of the first radial magnetic bearing is obtained. x1 , the first radial magnetic bearing y-direction compensation current Δi y1 , the second radial magnetic bearing x-direction compensation current Δi x2 , the second radial magnetic bearing y-direction compensation current Δi y2 ;

[0009] Step S3: Compare the first radial magnetic bearing x-direction displacement feedback signal x1 with the first radial magnetic bearing x-direction given displacement signal x1 * The first displacement control loop outputs the initial given current i in the x direction of the first radial magnetic bearing. x1 * ; The first radial magnetic bearing y direction displacement feedback signal y1 and the first radial magnetic bearing y direction given displacement signal y1 * The initial given current i in the y direction of the first radial magnetic bearing is output through the second displacement control loop. y1 * ; The second radial magnetic bearing x direction displacement feedback signal x2 and the second radial magnetic bearing x direction given displacement signal x2 * The initial given current i in the x direction of the second radial magnetic bearing is output through the third displacement control loop. x2 * ; The second radial magnetic bearing y direction displacement feedback signal y2 and the second radial magnetic bearing y direction given displacement signal y2 * The initial given current i in the y direction of the second radial magnetic bearing is output through the fourth displacement control loop. y2 * ;

[0010] Step S4: the synthetic vibration acceleration a s With a given acceleration a s * The given current i of the suspension winding of the bearingless motor is obtained through the acceleration control loop. s * At the same time, the first radial magnetic bearing x direction compensation current Δi x1 The first radial magnetic bearing has an initial given current i in the x direction. x1 * The actual control given current i in the x direction of the first radial magnetic bearing is obtained by calculation xa1 * ; The first radial magnetic bearing y direction compensation current Δi y1 The first radial magnetic bearing has an initial given current i in the y direction. y1 *The actual control given current i in the y direction of the first radial magnetic bearing is obtained by calculation ya1 * ; The second radial magnetic bearing x direction compensation current Δi x2 The second radial magnetic bearing has an initial given current i in the x direction. x2 * The actual control given current i in the x direction of the second radial magnetic bearing is obtained by calculation xa2 * ; The second radial magnetic bearing y direction compensation current Δi y2 The second radial magnetic bearing has an initial given current i in the y direction. y2 * The actual control current i in the y direction of the second radial magnetic bearing is obtained by calculation. ya2 * ;

[0011] Step S5, the suspension winding of the bearingless motor is given a current i s * With the feedback current i s The duty cycle D of the three-phase full-bridge converter switch is output through the first current control loop. s , the bearingless motor is controlled by a three-phase full-bridge converter; at the same time, the first radial magnetic bearing is actually controlled in the x direction to give a given current i xa1 * The first radial magnetic bearing x-direction feedback current i x1 The difference is output through the second current control loop to output the first duty cycle D of the first switching power amplifier. x1 The first radial magnetic bearing y direction actual control given current i ya1 * The first radial magnetic bearing y direction feedback current i y1 The difference is output through the third current control loop to output the second duty cycle D of the first switching power amplifier. y1 ; The second radial magnetic bearing x direction actually controls the given current i xa2 * The feedback current i in the x direction of the second radial magnetic bearing x2 The difference is output through the fourth current control loop to output the first duty cycle D of the second switching power amplifier. x2 The second radial magnetic bearing y direction actually controls the given current i ya2 * The feedback current i in the y direction of the second radial magnetic bearing y2 The difference is output through the fifth current control loop to output the second duty cycle D of the second switching power amplifier. y2 ; Finally, the first radial magnetic bearing and the second radial magnetic bearing are controlled by the first switching power amplifier and the second switching power amplifier respectively.

[0012] In a preferred embodiment of the present invention, the first vibration acceleration sensor and the second vibration acceleration sensor are placed on the housing of the bearingless motor at an orthogonal angle of 90 degrees.

[0013] In a preferred embodiment of the present invention, the acceleration control loop adopts a PI regulator.

[0014] In a preferred embodiment of the present invention, the first displacement control loop, the second displacement control loop, the third displacement control loop, and the fourth displacement control loop use PID regulators.

[0015] In a preferred embodiment of the present invention, the first current control loop, the second current control loop, the third current control loop, the fourth current control loop, and the fifth current control loop use PI regulators.

[0016] The present invention has the following beneficial effects:

[0017] (1) The present invention adds two vibration acceleration sensors placed at 90° orthogonal angles to the motor housing, thereby obtaining vibration accelerations in two orthogonal directions and further obtaining the eccentric state of the rotating shaft.

[0018] (2) After obtaining the vibration force of the bearingless motor, the present invention uses the LMS adaptive filtering algorithm to estimate the vibration force at the first radial magnetic bearing and the second radial magnetic bearing, thereby eliminating the vibration acceleration sensor at the radial magnetic bearing.

[0019] (3) The present invention obtains the given current i of the suspension winding of the bearingless motor by adding a vibration acceleration regulator. s * , and perform closed-loop control to effectively reduce the vibration of bearingless motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a four-degree-of-freedom suspension system of the present invention.

[0021] Figure 2 This is a control block diagram of a four-degree-of-freedom radial vibration suppression strategy of the present invention. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be interpreted as limiting the present invention.

[0023] Figure 1A schematic structural diagram of a four-degree-of-freedom suspension system of the present invention. A four-degree-of-freedom suspension system of the present invention includes a radial magnetic bearing 1, a bearingless motor 3 and a radial magnetic bearing 2, wherein the radial magnetic bearing 1, the radial magnetic bearing 2 and the bearingless motor 3 are coaxially connected. The radial magnetic bearing 1, the radial magnetic bearing 2 and the bearingless motor 3 can all be used to provide the radial force required for four-degree-of-freedom suspension. In order to detect the vibration displacement of the system, the present invention adds two vibration acceleration sensors 4 and vibration acceleration sensors 5 placed at 90° orthogonally to the housing of the bearingless motor 3, which are used to measure the vibration acceleration of the system in the horizontal and vertical directions, respectively.

[0024] Figure 2 This is a control block diagram of a four-degree-of-freedom radial vibration suppression strategy of the present invention. First, the vibration acceleration sensors 4 and 5 on the housing of the bearingless motor 3 read the vibration acceleration a in the horizontal and vertical directions. x , a y , after passing through the low-pass filter LPF 61, the output vibration acceleration a x1 , a y1 , and after passing through the synthesis module 62, the synthetic vibration acceleration a is obtained s At the same time, according to the vibration force distribution characteristics of the casing, the vibration force at the radial magnetic bearing 1 and the radial magnetic bearing 2 is estimated by the LMS adaptive filtering algorithm module 63, and then the x / y direction compensation current Δi is obtained. x1 , Δi y1 , Δi x2 , Δi y2 .

[0025] Secondly, the resultant acceleration a s As the feedback signal of the radial vibration acceleration ring on the bearingless motor side, it is compared with the given acceleration a s * The given current i of the suspension winding of the bearingless motor is obtained after the acceleration control loop 64. s * Among them, the acceleration control loop adopts PI regulator.

[0026] The radial magnetic bearings 1 and 2 are both controlled by displacement control loop and current control loop. By reading the radial displacements x1, y1, x2, y2 in the x / y direction, they are respectively compared with the given displacement x1 * 、y1 * 、x2 * ,y2 *The difference is used as the input signal of the first displacement control loop 65, the second displacement control loop 66, the third displacement control loop 67, and the fourth displacement control loop 68. The first displacement control loop 65, the second displacement control loop 66, the third displacement control loop 67, and the fourth displacement control loop 68 use PID regulators, and their output signals are the suspension given current i of the radial magnetic bearing 1 and the radial magnetic bearing 2. x1 * 、i y1 * 、i x2 * 、i y2 * Then, the x / y direction compensation current Δi x1 , Δi y1 , Δi x2 , Δi y2 The suspension given current i of radial magnetic bearing 1 and radial magnetic bearing 2 are respectively x1 * 、i y1 * 、i x2 * 、i y2 * Perform calculations to obtain the actual control given current i of radial magnetic bearing 1 and radial magnetic bearing 2. xa1 * 、i ya1 * 、i xa2 * 、i ya2 * .

[0027] The suspension winding of the bearingless motor 3 is given a current i s * With the feedback current i s The difference is used as the input of the first current control loop 69, and the output is the duty cycle D of the switch tube of the three-phase full-bridge converter 8. s Finally, the bearingless motor 3 is controlled by the three-phase full-bridge converter 8; at the same time, the actual control given current i of the radial magnetic bearing 1 and the radial magnetic bearing 2 is set. xa1 * 、i ya1 * 、i xa2 * 、i ya2 * Respectively with the feedback current i x1 、i y1 、i x2 、i y2The difference is used as the input of the second current control loop 71, the third current control loop 72, the fourth current control loop 73, and the fifth current control loop 74, and the output is the duty cycle D of the first switching power amplifier 91 and the second switching power amplifier 92. x1 、D y1 、D x2 、D y2 Finally, the radial magnetic bearing 1 and the radial magnetic bearing 2 are controlled by the first switching power amplifier 91 and the second switching power amplifier 92 respectively.

[0028] Furthermore, the first current control loop 69 , the second current control loop 71 , the third current control loop 72 , the fourth current control loop 73 , and the fifth current control loop 74 adopt PI regulators.

[0029] The above embodiments are only for illustrating the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A four-degree-of-freedom radial vibration suppression strategy, applied to a four-degree-of-freedom suspension system, characterized in that: The four-degree-of-freedom suspension system includes a bearingless motor, a first radial magnetic bearing, a second radial magnetic bearing, a first vibration acceleration sensor, and a second vibration acceleration sensor, wherein the first vibration acceleration sensor and the second vibration acceleration sensor are placed on the housing of the bearingless motor, including: Step S1: The first vibration acceleration sensor and the second vibration acceleration sensor collect the vibration acceleration a of the housing of the bearingless motor in real time. x and vibration acceleration a y , after passing through the low-pass filter, the output vibration acceleration a x1 and vibration acceleration a y1 , and obtain the synthetic vibration acceleration a s ; Step S2: According to the vibration force distribution characteristics of the housing, the vibration acceleration a is x , the vibration acceleration a y The LMS adaptive filtering algorithm is used to estimate the vibration force at the first radial magnetic bearing and the second radial magnetic bearing, and then the x-direction compensation current Δi of the first radial magnetic bearing is obtained. x1 , the first radial magnetic bearing y-direction compensation current Δi y1 , the second radial magnetic bearing x-direction compensation current Δi x2 , the second radial magnetic bearing y-direction compensation current Δi y2 ; Step S3: Compare the first radial magnetic bearing x-direction displacement feedback signal x1 with the first radial magnetic bearing x-direction given displacement signal x1 * The first displacement control loop outputs the initial given current i in the x direction of the first radial magnetic bearing. x1 * ; The first radial magnetic bearing y direction displacement feedback signal y1 and the first radial magnetic bearing y direction given displacement signal y1 * The initial given current i in the y direction of the first radial magnetic bearing is output through the second displacement control loop. y1 * ; The second radial magnetic bearing x direction displacement feedback signal x2 and the second radial magnetic bearing x direction given displacement signal x2 * The initial given current i in the x direction of the second radial magnetic bearing is output through the third displacement control loop. x2 * ; The second radial magnetic bearing y direction displacement feedback signal y2 and the second radial magnetic bearing y direction given displacement signal y2 * The initial given current i in the y direction of the second radial magnetic bearing is output through the fourth displacement control loop. y2 * ; Step S4: the synthetic vibration acceleration a s With a given acceleration a s * The given current i of the suspension winding of the bearingless motor is obtained through the acceleration control loop. s * At the same time, the first radial magnetic bearing x direction compensation current Δi x1 The first radial magnetic bearing has an initial given current i in the x direction. x1 * The actual control given current i in the x direction of the first radial magnetic bearing is obtained by calculation xa1 * ; The first radial magnetic bearing y direction compensation current Δi y1 The first radial magnetic bearing has an initial given current i in the y direction. y1 * The actual control given current i in the y direction of the first radial magnetic bearing is obtained by calculation ya1 * ; The second radial magnetic bearing x direction compensation current Δi x2 The second radial magnetic bearing has an initial given current i in the x direction. x2 * The actual control given current i in the x direction of the second radial magnetic bearing is obtained by calculation xa2 * ; The second radial magnetic bearing y direction compensation current Δi y2 The second radial magnetic bearing has an initial given current i in the y direction. y2 * The actual control current i in the y direction of the second radial magnetic bearing is obtained by calculation. ya2 * ; Step S5, the suspension winding of the bearingless motor is given a current i s * With the feedback current i s The duty cycle D of the three-phase full-bridge converter switch is output through the first current control loop. s , the bearingless motor is controlled by a three-phase full-bridge converter; at the same time, the first radial magnetic bearing is actually controlled in the x direction to give a given current i xa1 * The first radial magnetic bearing x-direction feedback current i x1 The difference is output through the second current control loop to output the first duty cycle D of the first switching power amplifier. x1 The first radial magnetic bearing y direction actual control given current i ya1 * The first radial magnetic bearing y direction feedback current i y1 The difference is output through the third current control loop to output the second duty cycle D of the first switching power amplifier. y1 ; The second radial magnetic bearing x direction actually controls the given current i xa2 * The feedback current i in the x direction of the second radial magnetic bearing x2 The difference is output through the fourth current control loop to output the first duty cycle D of the second switching power amplifier. x2 The second radial magnetic bearing y direction actually controls the given current i ya2 * The feedback current i in the y direction of the second radial magnetic bearing y2 The difference is output through the fifth current control loop to output the second duty cycle D of the second switching power amplifier. y2 ; Finally, the first radial magnetic bearing and the second radial magnetic bearing are controlled by the first switching power amplifier and the second switching power amplifier respectively.

2. A four-degree-of-freedom radial vibration suppression strategy according to claim 1, characterized in that: The first vibration acceleration sensor and the second vibration acceleration sensor are placed on the housing of the bearingless motor at an orthogonal angle of 90 degrees.

3. A four-degree-of-freedom radial vibration suppression strategy according to claim 1, characterized in that: The acceleration control loop adopts a PI regulator.

4. A four-degree-of-freedom radial vibration suppression strategy according to claim 1, characterized in that: The first displacement control loop, the second displacement control loop, the third displacement control loop, and the fourth displacement control loop adopt PID regulators.

5. A four-degree-of-freedom radial vibration suppression strategy according to claim 1, characterized in that: The first current control loop, the second current control loop, the third current control loop, the fourth current control loop, and the fifth current control loop adopt PI regulators.

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