CN215058911U - Magnetic bearing control system based on eddy current sensor - Google Patents
Magnetic bearing control system based on eddy current sensor Download PDFInfo
- Publication number
- CN215058911U CN215058911U CN202022854736.9U CN202022854736U CN215058911U CN 215058911 U CN215058911 U CN 215058911U CN 202022854736 U CN202022854736 U CN 202022854736U CN 215058911 U CN215058911 U CN 215058911U
- Authority
- CN
- China
- Prior art keywords
- eddy current
- sensor
- rotor
- coil
- current sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000001514 detection method Methods 0.000 claims abstract description 20
- 239000000523 sample Substances 0.000 claims abstract description 17
- 239000003990 capacitor Substances 0.000 claims abstract description 6
- 230000005672 electromagnetic field Effects 0.000 claims abstract description 5
- 238000012545 processing Methods 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 4
- 239000000725 suspension Substances 0.000 description 16
- 230000008093 supporting effect Effects 0.000 description 10
- 238000006073 displacement reaction Methods 0.000 description 8
- 239000004020 conductor Substances 0.000 description 6
- 238000013461 design Methods 0.000 description 5
- 230000005284 excitation Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000005339 levitation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000002500 effect on skin Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Landscapes
- Magnetic Bearings And Hydrostatic Bearings (AREA)
Abstract
The utility model discloses a magnetic bearing control system based on eddy current type sensor, its constitution includes: the device comprises an eddy current type sensor (1), an electromagnet (2), a rotor (3), a power amplifier (4) and a controller (5). The eddy current type sensor (1) detects the deviation of the rotor (3) relative to a reference position, a controller (5) sends a control signal, the control signal is converted into control current through a power amplifier (4), and the control current forms a corresponding electromagnetic field in the electromagnet (2) so that the rotor (3) is always kept at a set position; the eddy current sensor (1) is a high-frequency reflection type eddy current sensor. The high-frequency reflection type eddy current sensor consists of a pre-set and a probe, and a detection coil is arranged in the probe and connected with a capacitor in parallel to form an LC parallel resonance circuit. The technical effects of the utility model: the detection coil and the pre-stage are used interchangeably, and the differential coil structure is used for reducing the temperature drift of the coil, suppressing common mode noise and the like.
Description
Technical Field
The utility model relates to a magnetic suspension bearing control system field especially is applied to magnetic suspension bearing control system with eddy current type sensor.
Background
The magnetic suspension bearing is a novel high-performance bearing which utilizes electromagnetic force to suspend a rotor in a space so as to realize non-contact supporting between a motor stator and the rotor, has the advantages of high allowable rotating speed, low friction power consumption, no need of lubrication, long service life and the like, and is an ideal choice for a high-speed motor bearing. Different from the supporting force provided by the traditional mechanical bearing, the supporting force provided by the magnetic suspension bearing is a non-contact controllable electromagnetic force generated by time-varying current in a coil, and the magnitude of the electromagnetic force can be adjusted in real time by a control system in the working process of the magnetic suspension bearing, so that the supporting force which changes in real time is provided for the supporting element. Meanwhile, the magnetic suspension bearing is an electromechanical integrated product, and the supporting effect of the magnetic suspension bearing can be realized only by changing electromagnetic force through a control link, so that the supporting characteristic of the magnetic suspension bearing has an active characteristic and a passive characteristic at the same time, and only by comprehensively knowing the supporting characteristic of the magnetic suspension bearing, the changing electromagnetic force for maintaining the rotor at a balance position can be provided, so that the supporting characteristic of the magnetic suspension bearing meets the dynamic characteristic requirement of the rotor, and the aim of stably supporting the rotor is realized.
When the medium-low speed maglev train runs, no mechanical contact exists between the train body and the track, and in an outdoor environment, the environment is severe, and the temperature fluctuation range is large, so that the suspension gap sensor is required to be non-contact and can adapt to various complex environments. Compared with other non-contact measurement modes, the eddy current sensor performs non-contact measurement on the gap by detecting the eddy current effect between the coil and the measured conductor, is not influenced by a complex external environment, and is more suitable for the measurement range of several millimeters to dozens of millimeters. Therefore, the gap detection of the magnetic-levitation train generally adopts an eddy current type sensor.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present invention applies a novel gap sensor to a magnetic suspension bearing control system, and the specific technical solution is as follows:
a magnetic bearing control system based on an eddy current sensor comprises: the device comprises an eddy current type sensor (1), an electromagnet (2), a rotor (3), a power amplifier (4) and a controller (5). The eddy current type sensor (1) detects the deviation of the rotor (3) relative to a reference position, a controller (5) sends a control signal, the control signal is converted into control current through a power amplifier (4), and the control current forms a corresponding electromagnetic field in the electromagnet (2) so that the rotor (3) is always kept at a set position; the eddy current sensor (1) is a high-frequency reflection type eddy current sensor.
The high-frequency reflection type eddy current sensor consists of a pre-set and a probe, wherein a detection coil is arranged in the probe and is connected with a capacitor in parallel to form an LC parallel resonance circuit.
The components of the prepositioner are as follows: the device comprises a synchronous demodulation module, an A/D conversion module and a data processing module.
The detection coil adopts a rectangular coil with a large area, and the number of turns is 3.
The technical effects of the utility model: the interchangeability of the sensor means the capability of replacing components, parts or the whole sensor of the sensor with each other to keep the performance of the sensor unchanged, and for the electric eddy current type sensor, the detection coil and the prepositioner can be used interchangeably, and the electric eddy current type sensor realizes the interchangeability of the probe and the prepositioner. According to the influence of the thickness of the coil on the performance of the eddy current sensor, the thinner the coil, the larger the linear range, and the highest sensitivity and linearity of the sensor at a close distance are obtained; according to the influence of the shape and the geometric parameters of the coil on the performance of the eddy current sensor, the cross-sectional area of the cylindrical coil of the eddy current sensor and the number of turns of the coil have direct influence on the performance of the sensor; according to the structural parameter design of the planar eddy current coil, a method for increasing the outer diameter and reducing the inner diameter is provided, and the sensitivity of the planar eddy current coil can be effectively improved. In addition to adjusting the static characteristics, the detection coil structure design is also used to solve other problems: such as a differential coil configuration, is used to reduce temperature drift of the coil, suppress common mode noise introduced by the coil, and the like.
Drawings
FIG. 1 is a schematic diagram of an active magnetic suspension bearing control system.
Fig. 2 shows the principle of a high-frequency reflective eddy current sensor.
Fig. 3 is a diagram showing the basic composition of an eddy current sensor.
Fig. 4 is an equivalent circuit diagram of an eddy current sensor.
Fig. 5 shows a differential drive circuit.
Fig. 6 is a signal conditioning circuit.
In the figure: the device comprises an eddy current type sensor 1, an electromagnet 2, a rotor 3, a power amplifier 4 and a controller 5.
Detailed Description
The following description will further describe embodiments of the present invention with reference to the accompanying drawings.
1. Integral technical scheme
A magnetic bearing control system based on an eddy current sensor comprises: the device comprises an eddy current type sensor (1), an electromagnet (2), a rotor (3), a power amplifier (4) and a controller (5). The eddy current type sensor (1) detects the deviation of the rotor (3) relative to a reference position, a controller (5) sends a control signal, the control signal is converted into control current through a power amplifier (4), and the control current forms a corresponding electromagnetic field in the electromagnet (2) so that the rotor (3) is always kept at a set position; the eddy current sensor (1) is a high-frequency reflection type eddy current sensor. As shown in fig. 1 and 2.
The high-frequency reflection type eddy current sensor consists of a pre-set and a probe, wherein a detection coil is arranged in the probe and is connected with a capacitor in parallel to form an LC parallel resonance circuit. As shown in fig. 3.
The components of the prepositioner are as follows: the device comprises a synchronous demodulation module, an A/D conversion module and a data processing module. As shown in fig. 3.
The detection coil adopts a rectangular coil with a large area, and the number of turns is 3.
As a typical mechatronic product, the performance of each component of the active electromagnetic bearing comprehensively determines the performance of the whole system. Figure 1 shows a simple active electromagnetic bearing configuration. A typical active electromagnetic bearing system consists of a displacement sensor, a controller, an actuator (consisting of a power amplifier and an electromagnet), and a rotor. The controller receives a displacement signal from the displacement sensor relative to the rotor, generates a corresponding control signal compared with the expected levitation position, and transmits the control signal to the power amplifier, and the power amplifier drives the electromagnet to generate controllable electromagnetic force to enable the rotor to be levitated to the expected position.
2. Controller
The core of the active electromagnetic bearing is a controller, and the dynamic behavior of the high-speed moving rotor depends on the real-time control of the controller. The input of the controller comes from various sensors, mainly motion state signals of the rotor, such as displacement, rotating speed and the like; the output control signal controls the power amplifier of the later stage, and corresponding current is injected into the electromagnet, so that the rotor is controlled to suspend.
With the rapid development of integrated circuits such as microprocessors, digital-to-analog converters, analog-to-digital converters and the like, digital controllers have become the mainstream choice for constructing magnetic bearing systems.
The digital controller can realize various control algorithms such as nonlinear control, unbalance control algorithm and the like in a very flexible way. Through the realization of a complex control algorithm, the magnetic bearing system can obtain a plurality of excellent characteristics, such as reduction of bearing vibration to obtain high-precision positioning, inhibition of modal vibration to help the flexible rotor to be transcritical, reduction of power loss caused by vibration and the like.
In order to meet the control requirements of the modern magnetic bearing system, a plurality of processors are often selected to construct a digital controller. The different processors each perform a specific subtask. The DSP is a microprocessor special for real-time digital signal processing, adopts a Harvard architecture and a special instruction set of single-instruction multiple-data flow, is internally provided with a special hardware multiplier, has stronger floating point arithmetic performance than a general processor, is particularly suitable for running various control algorithms, and has wide application in a magnetic suspension bearing system. However, the peripheral expansion capability of the DSP is limited, and the DSP cannot meet the data input and output requirements of the multi-degree-of-freedom magnetic suspension bearing, so that the programmable logic device FPGA or CPLD is often used to assist in building the controller. The FPGA is a programmable integrated circuit, and the design and verification are finished by utilizing synthesis, layout and wiring and a time sequence simulation tool through a logic circuit described by a hardware description language Verilog HDL.
The FPGA is suitable for constructing a parallelized high-speed data acquisition and real-time control system, and can realize the functions of multi-degree-of-freedom displacement signal acquisition, power amplifier control, data preprocessing, digital filtering and the like.
3. Power amplifier
In an active magnetic bearing system, a power amplifier receives a control signal output by a controller and converts the control signal into a current required by an electromagnet coil, so that a strong magnetic field is established to suspend a controlled rotor.
In pursuit of higher efficiency and smaller size, integrated switching power amplifier power amplifiers are commonly used in magnetic suspension bearing systems. The power device used by the switch power amplifier works in a switch state, so that compared with a linear power amplifier, the loss is greatly reduced, and the efficiency is higher. However, the current ripple of the switch power amplifier is much higher than that of the linear power amplifier, and the high current ripple can cause the rotor to vibrate at high frequency and generate higher eddy current loss to heat the stator and the rotor. Therefore, the key point of the design of the magnetic bearing power amplifier is to reduce the current ripple of the switch power amplifier.
The switch power amplifier technology has been developed for many years, and the control modes mainly include sampling hold control, current hysteresis control, pulse width modulation and the like.
The sample-and-hold control is driven by a fixed clock, compares the current signal with the control signal at the rising edge of the clock, and determines the tube switch state during that period. The control method is simple to implement, but the power tube only starts to switch in each period, so that the current ripple is large and the distortion is serious.
The current hysteresis control gives a current hysteresis width, and the power tube is switched when the current reaches the upper limit and the lower limit of the hysteresis width, so that the current is ensured to fluctuate in the hysteresis width. In the method, the switching time of the tube is not fixed, so that the noise interference of the switch cannot be avoided, and the noise can influence the sampling result of the displacement sensor, thereby influencing the control effect of the magnetic bearing.
The pulse width modulation is to generate the switch of the pulse control tube with different duty ratios by comparing the actual current signal with the control signal. The common modulation mode has two levels and three levels, wherein the current of the coil of the former is only increased or decreased in two states, and the current of the latter is increased in a follow current state, so that the current ripple in the coil is greatly reduced.
Pulse width modulated three-level switching power amplifiers have been widely studied and used due to their low ripple characteristics.
4. Electric eddy current sensor
The gap sensor researched by the invention belongs to a high-frequency reflection type eddy current sensor, as shown in fig. 2, a high-frequency signal source with stable frequency excites a detection coil, a high-frequency electromagnetic field phi 1 acts on the surface of a detected conductor, the skin effect enables phi 1 not to penetrate through the conductor and only acts on the surface layer of the conductor, and the eddy current magnetic field phi 2 is opposite to the direction of phi 1, so that the equivalent inductance is reduced, and the gap x is in one-to-one correspondence relation. Along with the change of x, the output electric quantity of the detection coil changes, and the output of the sensor is obtained after signal processing.
Eddy current sensors typically consist of a pre-stage and a probe, as shown in fig. 3. The detection coil is arranged in the probe and is connected with the capacitor in parallel to form an LC parallel resonance circuit. When the probe is in no-load, a high-frequency signal (f is more than or equal to 1MHz) is added in the detection coil, and the capacitance value of the resonance capacitor is adjusted, so that the probe works near a resonance point when the probe is in no-load.
In practical applications, the relationship between the coil and the conductor in eddy current testing can be equated with a weakly coupled transformer. The detected body is regarded as a short circuit coil and is magnetically connected with the detection coil of the probe. The detection coil is regarded as the primary side of the transformer, the eddy current circuit in the measured body is regarded as the secondary side, and the equivalent circuit of the sensor is shown in figure 4.
In the figure R2Is the measured body resistance, L2Is the inductance of the measured body, and M is the mutual inductance between the coil and the measured body (
k is the coupling coefficient) and U is the excitation voltage. Taking the current shown in the figure as a positive direction, obtaining an equation according to kirchhoff's law:
by solving the above formula to obtain I1And I2Comprises the following steps:
the equivalent impedance of the coil affected by the measured body is obtained as follows:
so that the equivalent resistance and the equivalent inductance of the obtained coil are respectively as follows:
the quality factor Q of the resulting simplified model of the coil is:
in the above formula, the first and second carbon atoms are,
the quality factor of the coil in no load;
The drive circuit and the probe circuit of the sensor are separated, and a drive signal needs to be introduced through a lead wire. When the lead is long, distributed inductance, capacitance and resistance of the lead can influence resonance of an excitation coil of the sensor. Meanwhile, signals up to several MHz are introduced from the outside, the quality of the signals per se is deteriorated, and components passing through during wiring are affected.
One solution is to integrate the driver circuit and the probe circuit, which puts high demands on the integration level of the driver circuit. The originally designed voltage source uses a push-pull drive circuit, discrete devices occupy a large amount of space, and the transistor's tube voltage drop effectively reduces the voltage applied to the excitation coil. Replacing the original discrete device design with a high performance integrated op-amp will help reduce space usage without the transistor base to emitter tube drop loss and more voltage can be applied to the drive coil.
The integrated transverse flux sensor still employs differential excitation, which simplifies the circuit as shown in fig. 5.
After the voltage signal on the sensor induction coil is detected, the residual high-frequency component during detection can be eliminated only by low-pass filtering, and subsequent difference and offset processing are carried out, so that the displacement signal which finally meets the requirements is output.
An infinite gain multi-feedback second-order low-pass filter is selected, and the circuit is shown in figure 6. According to the cutoff frequency of 10kHz, respectively taking R1＝R2＝11kΩ、R3＝6.2kΩ、C1＝1nF、C23.9 nF. Obtaining a transfer function of the filter as
Theoretically, the dynamic response characteristic of the sensor is mainly determined by a peak detection link and a second-order low-pass filtering link. The transfer function is G1(s) and G2The product of(s) can be described as
According to the amplitude-frequency and phase-frequency characteristic curves corresponding to G(s), the bandwidth of the sensor is about 9.54Hz, which is enough to meet the displacement detection requirement of magnetic bearings of tens of thousands of revolutions per minute.
Claims (3)
1. A magnetic bearing control system based on an eddy current sensor comprises: eddy current type sensor (1), electro-magnet (2), rotor (3), power amplifier (4), controller (5), the skew of rotor (3) relative to reference position is detected in eddy current type sensor (1), send a control signal by controller (5), change into control current through power amplifier (4), control current forms corresponding electromagnetic field in electro-magnet (2) for rotor (3) remain on setting for a position all the time, its characterized in that: the eddy current sensor (1) is a high-frequency reflection type eddy current sensor and consists of a prepositive device and a probe, wherein a detection coil is arranged in the probe and is connected in parallel with a capacitor to form an LC parallel resonance circuit.
2. The eddy current sensor-based magnetic bearing control system of claim 1, wherein: the components of the prepositioner are as follows: the device comprises a synchronous demodulation module, an A/D conversion module and a data processing module.
3. The eddy current sensor-based magnetic bearing control system of claim 1, wherein: the detection coil adopts a rectangular coil, and the number of turns is 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022854736.9U CN215058911U (en) | 2020-12-02 | 2020-12-02 | Magnetic bearing control system based on eddy current sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022854736.9U CN215058911U (en) | 2020-12-02 | 2020-12-02 | Magnetic bearing control system based on eddy current sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215058911U true CN215058911U (en) | 2021-12-07 |
Family
ID=79161199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022854736.9U Expired - Fee Related CN215058911U (en) | 2020-12-02 | 2020-12-02 | Magnetic bearing control system based on eddy current sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215058911U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116696946A (en) * | 2023-08-02 | 2023-09-05 | 山东华东风机有限公司 | Magnetic suspension bearing control device and control method |
-
2020
- 2020-12-02 CN CN202022854736.9U patent/CN215058911U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116696946A (en) * | 2023-08-02 | 2023-09-05 | 山东华东风机有限公司 | Magnetic suspension bearing control device and control method |
| CN116696946B (en) * | 2023-08-02 | 2023-10-20 | 山东华东风机有限公司 | Magnetic suspension bearing control device and control method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105634241B (en) | Micro-nano positioning device and its voice coil motor | |
| CN103591138B (en) | A kind of with polar form monocycle hybrid magnetic bearing | |
| CN215058911U (en) | Magnetic bearing control system based on eddy current sensor | |
| Wu et al. | An LVDT-based self-actuating displacement transducer | |
| CN105673688B (en) | A kind of self-regulated integer five degree of freedom magnetic bearing | |
| CN105121875B (en) | Magnetic bearing apparatus and the vacuum pump for having the magnetic bearing apparatus | |
| Bonfitto et al. | Resonant inductive displacement sensor for active magnetic bearings | |
| Zhang et al. | Analysis and design of a novel magnetic levitation gravity compensator with low passive force variation in a large vertical displacement | |
| CN103591137B (en) | The how ring-like hybrid magnetic bearing of a kind of heteropole | |
| Sato | High-precision and high-speed positioning of 100 G linear synchronous motor | |
| CN113452285B (en) | Electromagnetic suspension device | |
| Zhang et al. | Research on one-dimensional motion control system and method of a magnetic levitation ball | |
| Pechhacker et al. | Integrated electromagnetic actuator with adaptable zero power gravity compensation | |
| Prasad et al. | Electro-magnetic bearings with power electronic control for high-speed rotating machines: A review | |
| CN111077801A (en) | Magnetic bearing control method and control platform thereof | |
| Antila | Electromechanical properties of radial active magnetic bearings | |
| Cheng et al. | A unified design and the current ripple characteristic analysis of digital switching power amplifier in active magnetic-levitated bearings | |
| CN215058912U (en) | Magnetic suspension bearing control system based on novel gap sensor | |
| Wang et al. | Position estimation for self-sensing magnetic bearings based on double detection of current slopes | |
| Li et al. | Radial displacement detection using sensing coils weakly coupled with magnetic bearing | |
| Banerjee et al. | A review note on different components of simple electromagnetic levitation systems | |
| CN109723719B (en) | Differential detection type self-sensing electromagnetic bearing and implementation method thereof | |
| CN215990604U (en) | Electromagnetic suspension device | |
| Sato et al. | High-speed positioning of ultrahigh-acceleration and high-velocity linear synchronous motor | |
| Zingerli et al. | Rotor position measurement for a magnetically levitated 500'000 rpm permanent magnet machine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20211207 |