Digital integrated type electromagnetic bearing controller and control method thereof

Abstract

The application relates to a digital integrated electromagnetic bearing controller and a control method thereof, which comprises an electromagnetic bearing control core, a sampling and conditioning circuit, and a power conversion and driving circuit. The analog-to-digital converter in the electromagnetic bearing control core receives the voltage value signal representing the rotor position of the electromagnetic bearing and the coil current of the bearing stator after being collected and conditioned by the sampling and conditioning circuit, and sends the signal to the CPU controller after analog-to-digital conversion. The CPU controller outputs the duty cycle of the driving PWM signal to the PWM generator. The PWM generator outputs the driving signal to the power conversion and driving circuit. The driving circuit realizes the matching of the PWM signal output by the electromagnetic bearing control core, and converts the signal into the driving level of the power conversion circuit. Under the action of the driving level, the power conversion circuit converts the input DC power into a controllable current to supply power to the electromagnetic bearing stator coil. Only one controller is used, combined with the electromagnetic bearing control method, supplemented by appropriate peripheral circuits, and the control requirements of electromagnetic bearings of different power levels are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of electromagnetic bearing control technology, in particular to a kind of digital integrated electromagnetic bearing controller and control method thereof. BACKGROUND

[0002] Electromagnetic bearing is a new type of bearing form, unlike traditional bearing using mechanical stress to support rotor, electromagnetic bearing realizes the suspension of rotor by electromagnetic force, thereby avoiding the mechanical contact and friction of stator and rotor, and bringing no wear, no need lubrication, low loss, easy to speed up and other advantages.

[0003] The core of realizing electromagnetic bearing rotor suspension is electromagnetic bearing controller, controller controls power amplifier output electric energy to electromagnetic bearing stator coil, thereby generating electromagnetic force. Controller detects electromagnetic bearing rotor position in real time, when deviation occurs with set suspension position, adjusts the output electric energy of power amplifier, makes electromagnetic force occur correction force opposite to position deviation, thereby realizing the dynamic suspension of rotor in given position.

[0004] Digital power amplifier circuit occupies mainstream due to its obvious efficiency advantage relative to analog power amplifier circuit. In existing electromagnetic bearing control technology, controller and power amplifier are generally designed separately, controller outputs control quantity to power amplifier, and the control chip of power amplifier converts the control quantity output by controller into driving signal of power electronic device, and finally realizes its function. Due to the existence of two control cores in physics, it causes the disadvantages of uncoordinated control, inflexible parameter design, small adaptive power range, etc. SUMMARY

[0005] In view of the above problems, a kind of digital integrated electromagnetic bearing controller and control method thereof are proposed.

[0006] The technical scheme of the present application is: a kind of digital integrated electromagnetic bearing controller, including electromagnetic bearing control core, sampling and conditioning circuit, power conversion and driving circuit;

[0007] Electromagnetic bearing control core is composed of CPU controller, analog-to-digital converter and PWM generator, the analog-to-digital converter accepts the voltage value signal representing electromagnetic bearing rotor position and bearing stator coil current collected and conditioned by sampling and conditioning circuit, and sends CPU controller after analog-to-digital conversion, CPU controller outputs duty cycle of driving PWM signal to PWM generator;PWM generator outputs driving signal to power conversion and driving circuit;

[0008] The sampling and conditioning circuit includes displacement signal conditioning circuit and current signal conditioning circuit, adjusts the voltage value of the sampled voltage value signal representing electromagnetic bearing rotor position signal and bearing stator coil current signal to the effective voltage range of analog input end of analog-to-digital converter, and carries out high frequency suppression;

[0009] The power conversion and drive circuit is composed of a power conversion circuit and a drive circuit, the drive circuit realizes matching with the PWM signal output by the electromagnetic bearing control core, and converts the drive level of the power conversion circuit, under the action of the drive level, the power conversion circuit converts the input DC power into a controllable current to supply power to the electromagnetic bearing stator coil.

[0010] A control method of a digital integrated electromagnetic bearing controller, the control method runs in the CPU controller of the digital integrated electromagnetic bearing controller, and realizes dynamic suspension control through the organic combination of electromagnetic bearing rotor position outer loop PID control and bearing stator coil current inner loop PI control.

[0011] Further, the electromagnetic bearing rotor position outer loop PID control: the input is the difference between the given position and the feedback position of the electromagnetic bearing rotor, and the output current control amount is sent to the bearing stator coil current inner loop after passing through the PID controller:

[0012] The bearing stator coil current inner loop PI control is composed of a pair of differential PI controllers, wherein: the input of the PI(+) controller is the current bias value+the output current control amount of the position outer loop, and the output is the duty cycle of the drive PWM signal of the bearing stator coil A, which is sent to the PWM generator; the input of the PI(-) controller is the current bias value-the output current control amount of the position outer loop, and the output is the duty cycle of the drive PWM signal of the bearing stator coil B, which is sent to the PWM generator; wherein the current bias value is determined by the design result of the electromagnetic bearing body and is a fixed constant.

[0013] Further, the control method of the digital integrated electromagnetic bearing controller, when the electromagnetic bearing is a 5-degree-of-freedom system, including a 4-degree-of-freedom radial system and a 1-degree-of-freedom axial system, a total of 5 electromagnetic bearing control cores are needed to control five translational directions of left x direction xl, right x direction xr, left y direction yl, right y direction yr, and z direction z respectively; the position given is XL given, XR given, YL given, YR given, and Z given respectively; the position feedback is XL feedback, XR feedback, YL feedback, YR feedback, and Z feedback respectively; the current control amount is i-XL, i-XR, i-YL, i-YR, and i-Z respectively; when the electromagnetic bearing is a 4-degree-of-freedom system, including a 4-degree-of-freedom radial system, a total of 4 electromagnetic bearing control cores are needed to control four translational directions of left x direction xl, right x direction xr, left y direction yl, and right y direction yr respectively.

[0014] Further, the 4 or 5 degree of freedom system increases the cross feedback link to form a cross feedback PID control to jointly control four or five translational directions and solve the gyroscopic effect problem.

[0015] Further, the 4 or 5 degree of freedom system adds a notch filter link, the input is the difference between the position given and the position feedback, the notch angular frequency w, and the output is the signal after notch processing sent to the PID controller, which suppresses the vibration of a specific frequency.

[0016] The digital integrated electromagnetic bearing controller and the control method thereof have the advantages that only one controller is used, the electromagnetic bearing control method is combined, appropriate peripheral circuits are supplemented, the position control of the electromagnetic bearing rotor and the driving signal modulation of the power amplifier device are realized, the configuration parameters of the position regulator and the current regulator can be flexibly adjusted through software, and thus the control requirements of electromagnetic bearings of different power levels are met. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The figure is a structural block diagram of the digital integrated electromagnetic bearing controller of the application.

[0018] Figure 2 The figure is a control method schematic diagram of the digital integrated electromagnetic bearing controller of the application.

[0019] Figure 3 The figure is a cross feedback PID control schematic diagram in the control method of the digital integrated electromagnetic bearing controller of the application.

[0020] Figure 4 The figure is a notch filter link schematic diagram in the control method of the digital integrated electromagnetic bearing controller of the application. DETAILED DESCRIPTION

[0021] The application will be described in detail below in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical scheme of the application, detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0022] The figure is a structural block diagram of the digital integrated electromagnetic bearing controller of the application, which is the digital integrated electromagnetic bearing controller of the application; and includes an electromagnetic bearing control core, a sampling and conditioning circuit, and a power conversion and driving circuit. Figure 1 The electromagnetic bearing control core is composed of a CPU controller, an analog-to-digital converter and a PWM generator and is connected through an internal bus.

[0023] The analog-to-digital converter in the electromagnetic bearing control core receives the voltage value signal representing the position of the electromagnetic bearing rotor and the coil current of the bearing stator after being collected and conditioned by the sampling and conditioning circuit, sends the signal to the CPU controller after analog-to-digital conversion, and outputs the duty cycle of the driving PWM signal to the PWM generator; the PWM generator in the electromagnetic bearing control core outputs the driving signal to the power conversion and driving circuit.

[0024] The sampling and conditioning circuit comprises a displacement signal conditioning circuit and a current signal conditioning circuit, which adjusts the voltage value of the sampled voltage value representing the electromagnetic bearing rotor position signal and the bearing stator coil current signal to the effective voltage range of the analog input end of the analog-to-digital converter, and performs appropriate high-frequency suppression.

[0025] The power conversion and driving circuit is composed of a power conversion circuit and a driving circuit, the driving circuit realizes matching with the PWM signal output by the electromagnetic bearing control core, and converts the driving level of the power conversion circuit, under the action of the driving level, the power conversion circuit converts the input direct current power into a controllable current to supply power to the electromagnetic bearing stator coil.

[0026] The control method of the digital integrated electromagnetic bearing controller provided by the application realizes dynamic suspension control through the organic combination of the electromagnetic bearing rotor position outer loop PID control and the bearing stator coil current inner loop PI control. Figure 2 Dotted box

[0027] The electromagnetic bearing rotor position outer loop PID control: the input is the difference between the given position and the feedback position of the electromagnetic bearing rotor, which is input into the PID controller, and the output current control amount is sent to the bearing stator coil current inner loop.

[0028] The bearing stator coil current inner loop PI control: it is composed of a pair of differential PI controllers, wherein: the input of the PI(+) controller is the current bias value + the output current control amount of the position outer loop, the output is the duty cycle of the driving PWM signal of the bearing stator coil A, which is sent to the PWM generator; the input of the PI(-) controller is the current bias value - the output current control amount of the position outer loop, and the output is the duty cycle of the driving PWM signal of the bearing stator coil B, which is sent to the PWM generator; the current bias value (I_O) in the formula is determined by the design result of the electromagnetic bearing body, and is a fixed constant. Figure 2

[0029] For the electromagnetic bearing 5-degree-of-freedom system (including a 4-degree-of-freedom radial system and a 1-degree-of-freedom axial system), a total of 5 Figure 2 The electromagnetic bearing control core shown in the formula controls five translational directions of left x direction xl, right x direction xr, left y direction yl, right y direction yr and z direction z respectively. Figure 2 The position given in the formula is XL given, XR given, YL given, YR given and Z given respectively. Figure 2 The position feedback in the formula is XL feedback, XR feedback, YL feedback, YR feedback and Z feedback respectively. Figure 2 The current control amount in the formula is i-XL, i-XR, i-YL, i-YR and i-Z respectively.

[0030] ​For radial 4-DOF system, in order to solve the gyroscopic effect problem, increase Figure 3 cross feedback link (commonly control xl, xr, yl, yr four translation direction) shown in the figure, constitute cross feedback PID control. Wherein, with Figure 3 the dashed box in part of the content to replace Figure 2 CPU in the PID controller. As Figure 3 shown in the radial 4-DOF system cross feedback PID controller, input includes four direction position given and position feedback and speed w, wherein the speed w is obtained from the outside (speed measurement module or communication) by CPU controller, four direction position given and position feedback are XL given, XL feedback, XR given, XR feedback, YL given, YL feedback, YR given, YR feedback; Internal parameter K is determined by the electromagnetic bearing body design result, which is a fixed value; The output is the current control amount of four directions, namely i-XL, i-XR, i-YL, i-YR.

[0031] Parameter K is determined by the following formula: K=C*Jz / (Ki*L 2 ), wherein C is the cross feedback coefficient, taking value between 0.5 and 1; Jz is the rotational inertia of the rotor around Z direction; Ki is the current stiffness of electromagnetic bearing; L is the length of the shaft.

[0032] The difference between the XL given and the XL feedback, one way to send into the PID controller (XL), the PID controller (XL) output XL current PID control amount; One way to send into a first-order difference element output XL position deviation difference value;

[0033] The difference between the XR given and the XR feedback, one way to send into the PID controller (XR), the PID controller (XR) output XR current PID control amount; One way to send into a first-order difference element output XR position deviation difference value;

[0034] The difference between the YL given and the YL feedback, one way to send into the PID controller (YL), the PID controller (YL) output YL current PID control amount; One way to send into a first-order difference element output YL position deviation difference value;

[0035] The difference between the YR given and the YR feedback, one way to send into the PID controller (YR), the PID controller (YR) output YR current PID control amount; One way to send into a first-order difference element output YR position deviation difference value;

[0036] The difference between the XL position deviation difference value and the XR position deviation difference value, and the product of the speed w and the parameter k is the cross feedback value from X to Y;

[0037] The difference between the YR position deviation differential value and the YL position deviation differential value, multiplied by the rotational speed w and the parameter k, is the cross feedback value from the Y direction to the X direction;

[0038] The difference between the XL current PID control amount and the cross feedback value from the Y direction to the X direction is the final XL current control amount i-XL; the sum of the XR current PID control amount and the cross feedback value from the Y direction to the X direction is the final XR current control amount i-XR;

[0039] The difference between the YL current PID control amount and the cross feedback value from the X direction to the Y direction is the final YL current control amount i-YL; the sum of the YR current PID control amount and the cross feedback value from the X direction to the Y direction is the final YR current control amount i-YR.

[0040] For the control loop of any direction (xl, xr, yl, yr, z), to solve the problem of suppressing vibration of a specific frequency (typical example: rotational speed same frequency vibration caused by radial imbalance), a notch filter link is added. Figure 4 Specifically, when the cross feedback PID control is not used, for the xl direction, the notch filter processes the difference between the XL given value and the XL feedback value, and the output of the notch filter replaces the difference between the original XL given value and the XL feedback value, which is sent to the PID controller (XL); for the xr direction, the notch filter processes the difference between the XR given value and the XR feedback value, and the output of the notch filter replaces the difference between the original XR given value and the XR feedback value, which is sent to the PID controller (XR); for the yl direction, the notch filter processes the difference between the YL given value and the YL feedback value, and the output of the notch filter replaces the difference between the original YL given value and the YL feedback value, which is sent to the PID controller (YL); for the yr direction, the notch filter processes the difference between the YR given value and the YR feedback value, and the output of the notch filter replaces the difference between the original YR given value and the YR feedback value, which is sent to the PID controller (YR); for the z direction, the notch filter processes the difference between the Z given value and the Z feedback value, and the output of the notch filter replaces the difference between the original Z given value and the Z feedback value, which is sent to the PID controller (Z);

[0041] When the radial 4-degree-of-freedom system uses cross feedback PID control, four notch filters are used respectively to process the difference between the XL given value and the XL feedback value, the difference between the XR given value and the XR feedback value, the difference between the YL given value and the YL feedback value, and the difference between the YR given value and the YR feedback value, and then send them to the cross feedback PID controller (the part in the dashed box). Figure 3

[0042] The notch filter link, the input is the signal to be processed (the difference between the position given value and the position feedback value), the notch angular frequency w (typically the angular frequency corresponding to the rotational speed), and the output is the signal processed by the notch. The control parameters in the notch filter include the notch ratio sigma and the phase shift angle a.

[0043] ​The signal to be processed is input into the trap filter link, the product of the output value of the wave limiting link in the last control period and the trap ratio sigma is multiplied by sin(wt), and the product is multiplied by sin(wt+a) after the integration link; the other product is multiplied by cos(wt), and the product is multiplied by cos(wt+a) after the integration link; the two products are summed; the difference between the signal to be processed and the sum is the output value of the trap filter link in the current control period.

[0044] The trap ratio sigma determines the speed of the trap filter link to realize the trap processing, the larger the sigma, the faster the trap processing speed, generally, the sigma can be selected between 5 and 50 in consideration of the rapidity and stability.

[0045] The phase shift angle alpha is set to match different angular frequencies and realize the phase angle stability in the full frequency range, and the typical values of the alpha for different frequency ranges are 0°, 90°, 180° and 270°.

[0046] For the typical 5-degree-of-freedom system (including a 4-degree-of-freedom radial system and a 1-degree-of-freedom axial system), the above cross feedback link and trap filter link are simultaneously contained to constitute a complete electromagnetic bearing control algorithm with the known frequency vibration suppression and gyro effect suppression functions.

[0047] The above-described embodiments only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A control method of a digital integrated electromagnetic bearing controller, characterized by, The digital integrated electromagnetic bearing controller comprises an electromagnetic bearing control core, a sampling and conditioning circuit, and a power conversion and driving circuit. The electromagnetic bearing control core is composed of CPU A controller, an analog-to-digital converter and PWM A generator, the analog-to-digital converter accepts the voltage value signal representing the electromagnetic bearing rotor position and bearing stator coil current collected and conditioned by the sampling and conditioning circuit, and sends the signal after analog-to-digital conversion to CPU The controller, CPU The controller outputs the duty cycle of the drive PWM Signal to PWM The generator; PWM The generator outputs the drive signal to the power conversion and drive circuit; The sampling and conditioning circuit comprises a displacement signal conditioning circuit and a current signal conditioning circuit, which adjusts the voltage values of the sampled voltage values representing the electromagnetic bearing rotor position signal and the bearing stator coil current signal to the effective voltage range of the analog input end of the analog-to-digital converter, and performs high-frequency suppression. The power conversion and drive circuit is composed of a power conversion circuit and a drive circuit. PWM The drive circuit realizes matching of the signals output by the electromagnetic bearing control core and converts the signals into a drive level of the power conversion circuit. Under the action of the drive level, the power conversion circuit converts the input DC power into a controllable current to supply power to the electromagnetic bearing stator coil. The control method is run in the digital integrated electromagnetic bearing controller CPU The controller runs through the electromagnetic bearing rotor position outer loop PID Control and bearing stator coil current inner loop PI The organic combination of control realizes dynamic suspension control; The electromagnetic bearing rotor position outer loop PID Control: input is the difference between the given position of the electromagnetic bearing rotor and the feedback position, which is passed through PID Controller, output current control quantity to the bearing stator coil current Inner loop: The bearing stator coil current inner loop PI Control: composed of a pair of differential PI controllers, where: PI (+ ) controller input is current bias value + position outer loop output current control amount, output is the drive A signal duty cycle of the bearing stator coil PWM , sent into PWM the generator; PI (- ) controller input is current bias value - position outer loop output current control amount, output is the drive B signal duty cycle of the bearing stator coil PWM , sent into PWM the generator; where the current bias value is determined by the electromagnetic bearing body design result, which is a fixed constant.

2. The control method of a digital integrated type electromagnetic bearing controller according to claim 1, characterized by, When the electromagnetic bearing is a 5-DOF system, including a 4-DOF radial system and a 1-DOF axial system, 5 electromagnetic bearing control cores are needed in total, respectively controlling the left x direction xl、 right x direction xr、 left y direction yl、 right y direction yr, z direction z five directions of translation; the position given is XL given, XR given, YL given, YR given, Z given; the position feedback is XL feedback, XR feedback, YL feedback, YR feedback, Z feedback; the current control quantity is i-XL , i-XR , i-YL , i-YR , i-Z ; when the electromagnetic bearing is a 4-DOF system, including a 4-DOF radial system, 4 electromagnetic bearing control cores are needed in total, respectively controlling the left x direction xl、 right x direction xr、 left y direction yl、 right y direction yr、 four directions of translation.

3. The control method of a digital integrated type electromagnetic bearing controller according to claim 2, characterized by, The 4 or 5 degree of freedom system increases cross feedback links to form cross feedback PID Control, common control four or 5 translation direction, solve the gyroscopic effect problem.

4. The control method of a digital integrated type electromagnetic bearing controller according to claim 2 or 3, characterized by, The 4 or 5 degree of freedom system, increasing the wave filter link, input is the difference of position given and position feedback, wave filter angular frequency w , output is the wave filter processed signal PID Controller, suppress the vibration of a specific frequency.

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