Magnetic suspension balance based on three-actuator structure

Abstract

The utility model discloses a magnetic suspension balance based on a three-actuator structure, and relates to the technical field of magnetic suspension measurement, the magnetic suspension balance comprises a balance main body housing, a three-actuator structure, a sensing system and an object carrying tray, the three-actuator structure is installed in the balance main body housing, and the three-actuator structure is installed in the object carrying tray. The three-actuator structure comprises three magnetic levitation actuators which are rotationally, symmetrically and evenly distributed, each magnetic levitation actuator comprises a magnetic levitation stator and a magnetic levitation rotor arranged correspondingly, the magnetic levitation stators are installed over the magnetic levitation rotors, and the magnetic levitation actuators are used for adjusting the levitation positions and postures of the magnetic levitation rotors. The sensing system is used for obtaining the position of the magnetic suspension rotor; and the loading tray is connected right below the three magnetic suspension rotors through a connecting mechanism. According to the magnetic suspension balance based on the three-actuator structure, the quality measurement precision is further improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of magnetic suspension measurement, and more specifically relates to a magnetic suspension balance based on a three-actuator structure. Background Art

[0002] Traditional mechanical balances use contact mechanical coupling structures and strain gauges as their main form, which convert the balance displacement caused by changes in sample mass into electrical signals. After the electrical signal is amplified, the change in sample mass can be obtained because the sample mass is proportional to the size of the electrical signal. It is a measuring instrument commonly used for high-precision measurements of trace items.

[0003] The friction caused by mechanical contact in mechanical balances affects the life of the balance and the measurement accuracy, which cannot be avoided and needs to be solved urgently. The magnetic suspension balance has the advantages of non-mechanical contact and high precision. It can be used to replace mechanical balances and is an ideal choice for high-precision mass monitoring of trace samples in chemical reactions.

[0004] Chinese patent application number CN201010104591.9 discloses a controllable fast-heating thermobalance reactor, which places samples and realizes heating operation through a lifting device. However, the heating rate and the jitter introduced in the lifting process will affect the measurement results.

[0005] The Chinese patent application number 201810320916.3 discloses a sulfur deposition test device based on a magnetic suspension balance, which achieves non-contact, high-precision measurement in a high-temperature, high-pressure, and high-corrosion environment. However, its structure is complex and its volume is large, which makes it inconvenient to operate and has high production costs. In addition, during the mass measurement process, due to the influence of environmental factors, the mover in the single actuator structure is prone to spin, which reduces the mass measurement accuracy.

[0006] A Chinese patent application with application number CN115540980A discloses a magnetic levitation balance and mass measurement method based on a three-actuator structure, in which a compact three-actuator balance improves the load-bearing capacity and stability of the balance through three sets of coils. However, the magnetic coupling method of the three coils and a permanent magnet has extremely high requirements on the coaxiality of the magnetic field center in the vertical direction, and it is difficult to control the flipping of the mover on the horizontal plane, and the accuracy improvement capability is limited.

[0007] Therefore, it is necessary to design a magnetic suspension balance with high measurement accuracy. Utility Model Content

[0008] In view of this, the purpose of the utility model is to provide a magnetic suspension balance based on a three-actuator structure to overcome the technical problems of poor stability and need to improve the measurement accuracy of the existing magnetic suspension balance.

[0009] To achieve the above object, the first object of the present utility model is to provide a magnetic levitation balance based on a three-actuator structure, comprising:

[0010] A balance main body housing;

[0011] A three-actuator structure installed inside the balance main body housing. The three-actuator structure includes three magnetically levitated actuators evenly distributed in a rotationally symmetric manner, and each magnetically levitated actuator includes a magnetic levitation stator and a corresponding magnetic levitation rotor. The magnetic levitation stator is installed directly above the magnetic levitation rotor, and the magnetically levitated actuator is used to adjust the suspension position and attitude of the magnetic levitation rotor;

[0012] A sensing system for obtaining the position of the magnetic levitation rotor; and

[0013] A load tray connected to the lower sides of the three magnetic levitation rotors through a connecting mechanism and located at the inner bottom of the balance main body housing.

[0014] Preferably, it further includes a hardware circuit, which includes a controller and a power amplifier circuit. The controller is used to execute a control algorithm to calculate corresponding signals according to the position of the magnetic levitation rotor to achieve stable suspension; the power amplifier circuit outputs a stable current signal under the action of a control signal, and at the same time, the power amplifier circuit includes a current measurement module for measuring the excitation current of the coil to analyze the mass of the sample to be measured.

[0015] Preferably, the sensing system includes three laser range sensors located inside the balance main body housing. The three laser range sensors are evenly distributed in a rotationally symmetric manner and are respectively arranged directly above the three magnetic levitation stators.

[0016] Preferably, each magnetic levitation stator includes:

[0017] A coil holder;

[0018] A stator coil glued inside the coil holder;

[0019] A coil cover threadedly connected to the coil holder;

[0020] A stator permanent magnet glued to the coil cover and located in the internal space formed by the coil holder and the coil cover.

[0021] Preferably, each magnetic levitation rotor includes:

[0022] A rotor tray;

[0023] A connecting rod vertically threadedly connected inside the rotor tray;

[0024] The mover permanent magnet mounting cover is sleeved on the top of the connecting rod and is threadedly connected to the mover tray.

[0025] The mover permanent magnet is sleeved on the top of the connecting rod and is rotatably connected to the inside of the mover permanent magnet mounting cover through a bearing; the mover permanent magnet and the corresponding stator permanent magnet are located on the same vertical central axis.

[0026] Preferably, the balance body housing includes:

[0027] A square aluminum frame, which includes four vertically arranged first aluminum beams, second aluminum beams horizontally connected between the first aluminum beams, and square corner pieces connected between the ends of the first aluminum beams and the second aluminum beams;

[0028] An aluminum alloy panel, which is hermetically embedded in the face of the square aluminum frame, and a sample window for placing and taking samples is opened on the aluminum alloy panel;

[0029] A stator platform, which is horizontally connected inside the square aluminum frame. The stator platform includes an upper layer plate for fixing the laser ranging sensor and a lower layer plate for fixing the magnetic levitation stator. The laser ranging sensor is located between the upper layer plate and the lower layer plate, and the magnetic levitation stator is threadedly connected to the lower surface of the lower layer plate.

[0030] Preferably, the laser ranging sensor is vertically fixed on the upper layer plate through a sensor fixing plate, and the interference laser emitted by the laser ranging sensor is vertically emitted downward, passes through the light transmission hole on the lower layer plate and the light transmission hole of the coil seat, and irradiates the reflector located above the mover permanent magnet, and returns along the original optical path to form interference for high-precision position measurement.

[0031] Preferably, the power amplifier circuit includes:

[0032] A processing core, which is electrically connected to the controller;

[0033] A data conversion module, which is electrically connected to the processing core, and the data conversion module includes an A / D sampling module electrically connected to the laser ranging sensor and a D / A conversion module electrically connected to the stator coil;

[0034] A power amplifier and drive module, which uses an operational amplifier to output power and is used to drive the load of the stator coil;

[0035] A voltage regulation module, which amplifies the output voltage of the D / A conversion module by an appropriate multiple and outputs voltages with different positive and negative polarities;

[0036] A current measurement module converts the driving current provided to the stator coil into a voltage through a precision sampling resistor and sends the voltage to an analog input channel of an A / D conversion module for measurement;

[0037] The excitation current of the stator coil is provided by a power amplifier. At the same time, the current flowing through the stator coil during suspension is converted into a voltage signal through a sampling resistor, and then input into the controller through a differential amplifier and the processing core, so that the mass change of the measured sample is reflected by the current measurement value.

[0038] Preferably, the carrier tray is an alumina carrier basket, and the connecting mechanism is a sample hook.

[0039] Preferably, a vibration isolation pad is also provided at the bottom of the square aluminum frame.

[0040] Compared with the prior art, the utility model has the following advantages and effects:

[0041] The utility model discloses a magnetic suspension balance based on a three-actuator structure, which adopts three magnetic suspension actuators which are independently arranged. The three magnetic suspension actuators are distributed in rotational symmetry. Each magnetic suspension actuator consists of two parts, a magnetic suspension stator and a magnetic suspension mover. The magnetic suspension stator and the corresponding magnetic suspension mover are vertically arranged and located on a coaxial line, so that the three magnetic suspension movers can be stably suspended in a complex environment without generating spin or shaking. The sensing system adopts three laser distance measuring sensors which are distributed in rotational symmetry just above the three magnetic suspension stators, and can quickly and accurately measure the displacement of the mover part, thereby ensuring the accuracy of displacement detection in the vertical direction. Each laser distance measuring sensor is used to measure the suspension position of the corresponding magnetic suspension mover. The laser distance measuring sensor has the characteristics of high precision, non-contact and high sampling rate, and is convenient for data interaction with a main control system to form a closed-loop control and realize synchronous control of the three magnetic suspension actuators. The driving currents of the three magnetic suspension actuators can be synchronously controlled and accurately adjusted. The suspension position and posture of the magnetic suspension mover are adjusted by changing the electromagnetic force generated by the coil, so as to avoid the magnetic suspension mover from generating spin or shaking, so as to cope with the quality monitoring problem of trace samples in a complex reaction process. By analyzing the three-way coil current to invert the mass of the sample being measured, the shortcomings of the existing magnetic levitation balance, such as complex structure, large measurement noise and low measurement accuracy, are overcome, and non-contact, high-precision mass measurement can be achieved in a complex reaction environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of the three-dimensional structure of a magnetic suspension balance based on a three-actuator structure in an embodiment of the utility model;

[0043] Figure 2 This is a schematic diagram of the internal structure of a magnetic suspension balance based on a three-actuator structure in an embodiment of the utility model;

[0044] Figure 3 Structural schematic diagram of the magnetic levitation stator and the laser ranging sensor installed on the stator platform in the embodiment of the present utility model;

[0045] Figure 4 Three-dimensional structural schematic diagram of the magnetic levitation rotor in the embodiment of the present utility model;

[0046] Figure 5 Exploded structural schematic diagram of the magnetic levitation rotor in the embodiment of the present utility model;

[0047] Figure 6 Installation structural schematic diagram of the laser ranging sensor in the embodiment of the present utility model;

[0048] Figure 7 Installation structural schematic diagram of the magnetic levitation rotor in the embodiment of the present utility model;

[0049] Figure 8 Internal structural schematic diagram of the magnetic levitation stator in the embodiment of the present utility model;

[0050] Figure 9 Structural schematic diagram of the hardware circuit in the embodiment of the present utility model;

[0051] Figure 10 Schematic diagram of the balance mass measurement stability curve of the three-actuator structure in the embodiment of the present utility model;

[0052] Figure 11 Schematic diagram of the linear correction curve of the sample mass and the total current of the excitation coil in the embodiment of the present utility model.

[0053] Explanation of the reference numerals:

[0054] 1 - Balance main body housing;

[0055] 11 - Square aluminum frame; 111 - First aluminum beam; 112 - Second aluminum beam; 113 - Square corner piece;

[0056] 12 - Aluminum alloy panel;

[0057] 13 - Stator platform; 131 - Upper layer board; 132 - Lower layer board; 14 - Vibration isolation pad;

[0058] 2 - Three-actuator structure; 21 - Magnetic levitation actuator;

[0059] 211 - Magnetic levitation stator; 2111 - Coil cover; 2112 - Stator coil; 2113 - Coil seat; 2114 - Stator permanent magnet;

[0060] 212 - Magnetic levitation rotor; 2121 - Rotor permanent magnet mounting cover; 2122 - Rotor permanent magnet; 2123 - Connecting rod; 2124 - Bearing; 2125 - Rotor tray;

[0061] 3 - Laser ranging sensor; 31 - Sensor fixing plate;

[0062] 4 - Hardware circuit;

[0063] 41 - Controller; 42 - Power amplifier circuit; 421 - Processing core; 422 - Data conversion module; 423 - Power amplifier and drive module; 424 - Voltage regulation module; 425 - Current measurement module;

[0064] 5 - Carrying tray;

[0065] 6 - Connecting mechanism. Specific embodiments

[0066] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0067] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the communication inside two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0068] Please refer to Figures 1-9 As shown, the embodiment of the present invention provides a magnetic levitation balance based on a three - actuator structure. The magnetic levitation balance includes a balance main body housing 1, a three - actuator structure 2, and a sensing system, where:

[0069] The three - actuator structure 2 is installed inside the balance main body housing 1. The three - actuator structure 2 includes three magnetically levitated actuators 21 that are rotationally symmetrically and evenly distributed. Each magnetically levitated actuator 21 includes a magnetic levitation stator 211 and a corresponding magnetic levitation rotor 212. The magnetic levitation stator 211 is installed directly above the magnetic levitation rotor 212. The magnetically levitated actuator 21 is used to adjust the suspension position and attitude of the magnetic levitation rotor 212. The sensing system is used to obtain the position of the magnetic levitation rotor 212. The carrying tray 5 is connected to the lower sides of the three magnetic levitation rotors 212 through a connecting mechanism 6 and is located at the inner bottom of the balance main body housing 1.

[0070] Specifically, in the specific solution of this embodiment, the outer shell 1 of the balance main body in this embodiment serves as the main structure of the magnetic levitation motion actuator. On the one hand, it ensures that the internal measurement is not disturbed by the outside world. On the other hand, it also serves as the installation support carrier for the three-actuator structure 2 and the sensing system. The three-actuator structure 2 is composed of three independently arranged magnetic levitation actuators 21, and the three magnetic levitation actuators 21 are rotationally symmetrically distributed. Each magnetic levitation actuator 21 is composed of two parts: a magnetic levitation stator 211 and a magnetic levitation rotor 212. The magnetic levitation stator 211 and the corresponding magnetic levitation rotor 212 are vertically arranged and located on the same axis, so that the three magnetic levitation rotors 212 can stably levitate in a complex environment without spinning or shaking. The sensing system mainly includes a measurement unit for obtaining the position of the magnetic levitation rotor 212. This sensing system has the characteristics of high precision, non-contact, and high sampling rate, which is convenient for data interaction with the main control system to form a closed-loop control.

[0071] Therefore, the magnetic levitation balance based on the three-actuator structure in this embodiment adopts three independently arranged magnetic levitation actuators 21, and realizes the synchronous control of the three magnetic levitation actuators 21. The drive currents of the three magnetic levitation actuators 21 can be synchronously controlled and precisely adjusted. By changing the electromagnetic force generated by the coil, the levitation position and attitude of the magnetic levitation rotor 212 are adjusted to avoid its spinning or shaking, so as to cope with the quality monitoring problem of trace samples in a complex reaction process. By analyzing the three-line coil currents to invert the mass of the measured sample, it overcomes the shortcomings of the existing magnetic levitation balance, such as complex structure, large measurement noise, and low measurement accuracy, and can realize non-contact and high-precision mass measurement in a complex reaction environment.

[0072] Further, please refer to Figure 9 As shown, the hardware circuit 4 includes a controller 41 and a power amplifier circuit 42. The controller 41 is used to execute the control algorithm and calculate the corresponding signals according to the position of the magnetic levitation rotor 212 to achieve stable levitation. The power amplifier circuit 42 outputs a stable current signal under the action of the control signal. At the same time, the power amplifier circuit 42 includes a current measurement module for measuring the excitation current of the coil to analyze the mass of the measured sample;

[0073] In one embodiment, the hardware circuit 4 is mainly composed of a controller 41 and a power amplifier circuit 42. The controller 41 is used to execute the control algorithm and calculate the corresponding signals according to the positions of the three magnetic levitation rotors 212 to achieve the stable levitation of the three magnetic levitation rotors 212. The power amplifier circuit 42 outputs a stable current signal under the action of the control signal and measures the excitation current of the coil to analyze the mass of the measured sample.

[0074] It should be specifically noted here that the hardware circuit 4 in this embodiment is all prior art. The controller 41 and the power amplifier circuit 42 therein are both existing modules, and the position of the magnetic levitation mover 212 is designed based on the existing control program. Therefore, there is no improvement in any control program, and it will not be elaborated in detail here.

[0075] Further, please refer to Figure 1 、 3 As shown, the sensing system includes three laser ranging sensors 3 located inside the housing of the balance main body 1. The three laser ranging sensors 3 are rotationally symmetrically distributed and are respectively arranged directly above the three magnetic levitation stators 211.

[0076] Specifically in the technical solution of this embodiment, three laser ranging sensors 3 are provided, and the three laser ranging sensors 3 are rotationally symmetrically distributed directly above the three magnetic levitation stators 211. Each laser ranging sensor 3 is used to measure the suspension position of the corresponding magnetic levitation mover 212. It has a small volume and high measurement accuracy, and can collect the position and attitude information of the magnetic levitation mover 212 in real time.

[0077] Further, please refer to Figure 3 、 7 、8 As shown, each magnetic levitation stator 211 includes a coil cover 2111, a stator coil 2112, a coil seat 2113, and a stator permanent magnet 2114. Among them, the stator coil 2112 is adhesively fixed inside the coil seat 2113; the coil cover 2111 is threadedly connected to the coil seat 2113; the stator permanent magnet 2114 is adhesively fixed on the coil cover 2111, and the stator permanent magnet 2114 is located in the internal space formed by the coil seat 2113 and the coil cover 2111.

[0078] Specifically in the technical solution of the present invention, each magnetic levitation stator 211 is composed of a coil cover 2111, a stator coil 2112, a coil seat 2113, and a stator permanent magnet 2114. The internal space formed by threadedly connecting the coil seat 2113 and the coil cover 2111 accommodates the stator coil 2112 and the stator permanent magnet 2114. The setting of the stator permanent magnet 2114 is the key to the design. It can generate a magnetic force inward along the diameter direction to ensure that the magnetic levitation mover 212 will not roll over, thereby realizing stable suspension.

[0079] Further, please refer to Figure 1 、 2 、4, 5 As shown, each magnetic levitation mover 212 includes a mover permanent magnet mounting cover 2121, a mover permanent magnet 2122, a connecting rod 2123, a bearing 2124, and a mover tray 2125, where:

[0080] The connecting rod 2123 is vertically threadedly connected within the mover tray 2125; the mover permanent magnet mounting cover 2121 is passed through the top of the connecting rod 2123 and threadedly connected to the mover tray 2125; the mover permanent magnet 2122 is sleeved on the top of the connecting rod 2123 and is rotatably connected within the mover tray 2125 through a bearing 2124, and the mover permanent magnet 2122 and the corresponding stator permanent magnet 2114 are located on the same vertical central axis.

[0081] Specifically in the technical solution of the present utility model, the connecting rod 2123 is provided with a stepped hole at the top, the connecting rod 2123 is provided with a mounting bearing mounting position at the bottom, the connecting rod 2123 is press-fitted into the mover permanent magnet mounting cover 2121 through interference fit, the bottom end of the mover permanent magnet 2122 is rotatably connected to the mover tray 2125 through a bearing 2124. When the system is not started, the connecting rod 2123 can be placed on the limiting mechanism, so as to ensure that the mover quickly enters the working state after the magnetic levitation balance is powered on. The load tray 5 of the magnetic levitation balance is installed at the central position of the bottom of the mover tray 2125 through a connecting mechanism 6.

[0082] Further, please refer to Figure 1 as shown, the balance main body housing 1 includes a square aluminum frame 11, an aluminum alloy panel 12 and a stator platform 13, wherein:

[0083] The square aluminum frame 11 includes a first aluminum beam 111, a second aluminum beam 112 and a square corner piece 113. Four vertically arranged first aluminum beams 111 are located at the four corners to form a basic frame. The second aluminum beam 112 is horizontally connected between the first aluminum beams 111 to make the square aluminum frame 11 stable. The square corner piece 113 is connected between the ends of the first aluminum beam 111 and the second aluminum beam 112 to enable a fixed connection between the first aluminum beam 111 and the second aluminum beam 112.

[0084] The aluminum alloy panel 12 is hermetically embedded in the face of the square aluminum frame 11, and the aluminum alloy panel 12 is provided with a sample window for placing and taking samples. The sealing structure can fully reduce the interference of the outside world on the magnetic levitation balance during use, and can well overcome the measurement stability under the condition of air flow, and fully reduce the stabilization time of the magnetic levitation balance.

[0085] The stator platform 13 is horizontally connected within the square aluminum frame 11 for supporting and fixing the magnetic levitation stator 211 and the laser distance measuring sensor 3. In this embodiment, the stator platform 13 includes an upper layer board 131 and a lower layer board 132. The upper layer board 131 is used for fixing the laser distance measuring sensor 3, the lower layer board 132 is used for fixing the magnetic levitation stator 211, and the laser distance measuring sensor 3 is located between the upper layer board 131 and the lower layer board 132. The magnetic levitation stator 211 is threadedly connected to the lower surface of the lower layer board 132.

[0086] Preferably, a vibration isolation pad 14 is further provided at the bottom of the square aluminum frame 11 , and the vibration isolation pad 14 is made of rubber material.

[0087] It should be noted that the balance main body housing 1 can be formed by connecting a plurality of independent aluminum alloy panels 12 and a square aluminum frame 11 through corresponding threads. The four vertically supported first aluminum beams 111 have openings on the side for fixing the stator platform 13, and the stator platform 13 and the first aluminum beams 111 are connected by threads.

[0088] For further information, please refer to Figure 2 , 6 As shown, the laser ranging sensor 3 is vertically fixed on the upper plate 131 through the sensor fixing plate 31, and the interference laser emitted by the laser ranging sensor 3 is vertically emitted downward, passes through the light-transmitting holes on the lower plate 132 and the light-transmitting holes of the coil seat 2113, and irradiates the reflector located above the permanent magnet 2122 of the mover, and returns along the original light path, forming interference to perform high-precision position measurement.

[0089] In the specific scheme of this embodiment, three laser ranging sensors 3 are evenly distributed on the upper plate 131 of the balance main body shell 1, and are used to feed back the suspension position and posture of the magnetic levitation mover 212 to the controller 41 in real time. The controller 41 can synchronously control and accurately adjust the driving current in the three stator coils 2112, and adjust the suspension position and posture of the magnetic levitation mover 212 by changing the electromagnetic force generated by one or several coils to prevent it from spinning or shaking.

[0090] For further information, please refer to Figure 9 As shown, the power amplifier circuit 42 includes a processing core 421, a data conversion module 422, a power amplifier and driving module 423, a voltage regulation module 424 and a current measurement module 425, wherein:

[0091] The processing core 421 is electrically connected to the controller 41; the data conversion module 422 is electrically connected to the processing core 421, and the data conversion module 422 includes an A / D sampling module electrically connected to the laser ranging sensor 3 and a D / A conversion module electrically connected to the stator coil 2112; the power amplifier and driving module 423 uses an operational amplifier to output power and is used to drive the load of the stator coil 2112; the voltage regulation module 424 amplifies the output voltage of the D / A conversion module by a suitable multiple and outputs voltages of different polarities, positive and negative; the current measurement module 425 converts the driving current provided to the stator coil 2112 into a voltage through a precision sampling resistor, and sends it to the analog input channel of the A / D conversion module for measurement; the excitation current of the stator coil 2112 is provided by the power amplifier, and at the same time, the current flowing through the stator coil 2112 during suspension is converted into a voltage signal through the sampling resistor, and then through the differential amplifier, through the processing core 421, input into the controller 41, so that the current measurement value reflects the mass change of the sample being measured.

[0092] See also Figure 9 As shown, after the data collected by the three laser ranging sensors 3 (sensor array) in the sensing system are transmitted to the processing core 421, the processing core 421 analyzes and solves the position and posture of the mover tray 2125 in space, and after calculation by the closed-loop control algorithm, the motion of each degree of freedom is decoupled, and the control signal is transmitted to the current measurement module 425 to drive the electromagnetic coil to generate a corresponding electromagnetic force response; after stable suspension, the mass of the sample to be measured can be solved according to the linear model of the coil current and the sample mass obtained by calibration to complete the measurement task.

[0093] Specifically, see Figure 2 As shown, in this embodiment, the object tray 5 is an aluminum oxide object basket, and the connecting mechanism 6 is a sample hook. The object tray 5 of the magnetic suspension balance is preferably processed and assembled with non-magnetic materials to avoid interference with the magnetic field.

[0094] It is understandable that the loading tray 5 may also be made of other non-magnetic materials, such as copper alloy.

[0095] The specific working process of the magnetic suspension balance based on the three-actuator structure in this embodiment is as follows:

[0096] The three stator coils 2112 are powered to generate electromagnetic force, and the three magnetic suspension stators 211 simultaneously generate electromagnetic fields, which are respectively superimposed with the permanent magnetic fields generated by the mover permanent magnets 2122 located on the coaxial vertical line, generating suction force on the magnetic suspension mover 212, so that the magnetic suspension mover 212 is suspended;

[0097] Start the laser range finder 3 to measure the real-time position of the mover tray 2125. The controller 41 completes the closed-loop motion control of the system based on the position information transmitted by the three laser range finders 3, so that the three magnetic levitation movers 212 are stably levitated at the equilibrium height;

[0098] When a sample to be measured is placed on the load tray 5, the three magnetic levitation movers 212 can no longer be stably levitated at the equilibrium height. The three laser range finders 3 respectively feedback the suspension positions and attitude information of the three corresponding magnetic levitation movers 212 to the controller 41 in real time. The controller 41 adjusts the current flowing through the three stator coils 2112, and changes the electromagnetic force generated by the three stator coils 2112 to adjust the suspension positions and attitudes of the three magnetic levitation movers 212 to make them return to the equilibrium state again;

[0099] Adopt the current filtering algorithm to suppress signal noise and interference, and adopt the method of multi-variable function fitting to compensate for the zero drift of the collected signal;

[0100] By analyzing the current flowing through the three stator coils 2112, the mass of the measured sample is inverted to realize the measurement of the sample mass.

[0101] To verify the measurement accuracy of the magnetic levitation balance based on the three-actuator structure in the embodiment of the present invention, samples with 6 standard masses of 2.5mg, 5mg, 10mg, 20mg, 20mg, and 20mg are successively added to the alumina load basket without being taken out, and the result is as Figure 10 shown in the measurement result, where T r represents the steady-state excess time, and T m is the measurement time. The overshoot during the measurement process is caused by the impact of the falling heavy object on the actuator every time a heavy object is added to the alumina load basket, but this does not significantly extend the time required to reach the stable state.

[0102] Furthermore, Figure 11 gives the result of linear correction for the measured sample mass m and the total current I of the excitation coil t , where the black hollow points represent the effective measurement data during T m , the red straight line is the linear relationship obtained by fitting, and R is the Pearson correlation coefficient.

[0103] The final linear correlation coefficient between the test mass and the total current obtained from the measurement experiment reaches 0.99985. The conversion coefficient between the measured current and the mass is 28.948mg / mA.

[0104] As shown in Table 1 are the comparative test results of the three-actuator structure magnetic levitation balance and the single-actuator magnetic levitation balance, where R MSE and T rAll are taken from the average value of six weight measurements. Since the single-actuator magnetic levitation balance only has a single degree of freedom for displacement in the z-axis direction, T r is fixed at 10 s.

[0105] Table 1 Comparative test results of the three-actuator structure magnetic levitation balance and the single-actuator structure magnetic levitation balance

[0106]

[0107] It can be seen from the quantitative comparison results that the measurement accuracy of the three-actuator structure magnetic levitation balance in the embodiment of the present invention is improved by about 35.5% compared with the traditional single-actuator structure, and the heavier the fixed load, the more obvious the improvement in measurement accuracy. This is because the three-actuator structure not only increases the upper limit of the measured load but also effectively overcomes the rotational jitter problem existing in the balancing process of the single-actuator structure.

[0108] On the other hand, the T of the three actuators r is increased by 35.4% compared with the single actuator, and the improvement effects under different heavy loads are very similar. This shows that the three-degree-of-freedom motion decoupling and adaptive control algorithm of the three actuators are effective and can complete reliable measurement tasks within a more stable time.

[0109] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A magnetic levitation balance based on a three-actuator structure, characterized in that, Comprising: A balance main body housing (1); A three-actuator structure (2), installed inside the balance main body housing (1), the three-actuator structure (2) includes three magnetically levitated actuators (21) that are rotationally symmetrically and evenly distributed, and each of the magnetically levitated actuators (21) includes a magnetic levitation stator (211) and a corresponding magnetic levitation rotor (212). The magnetic levitation stator (211) is installed directly above the magnetic levitation rotor (212), and the magnetically levitated actuator (21) is used to adjust the suspension position and attitude of the magnetic levitation rotor (212); A sensing system for obtaining the position of the magnetic levitation rotor (212); and A load tray (5), connected to the lower sides of the three magnetic levitation rotors (212) through a connecting mechanism (6), and located at the inner bottom of the balance main body housing (1).

2. The magnetic levitation balance based on the three-actuator structure according to claim 1, wherein It further includes a hardware circuit (4), the hardware circuit (4) includes a controller (41) and a power amplifier circuit (42). The controller (41) is used to execute a control algorithm and calculate corresponding signals according to the position of the magnetic levitation rotor (212) to achieve stable suspension; the power amplifier circuit (42) outputs a stable current signal under the action of a control signal, and at the same time the power amplifier circuit (42) includes a current measurement module for measuring the excitation current of the coil to analyze the mass of the measured sample.

3. The magnetic levitation balance based on the three-actuator structure according to claim 2, characterized in that, The sensing system includes three laser range sensors (3) located inside the balance main body housing (1). The three laser range sensors (3) are rotationally symmetrically and evenly distributed and are respectively arranged directly above the three magnetic levitation stators (211).

4. The magnetic levitation balance based on a three-actuator structure according to claim 3, characterized in that, Each of the magnetic levitation stators (211) includes: A coil seat (2113); A stator coil (2112), adhesively bonded inside the coil seat (2113); A coil cover (2111), threadedly connected to the coil seat (2113); A stator permanent magnet (2114), adhesively bonded to the coil cover (2111) and located inside the internal space formed by the coil seat (2113) and the coil cover (2111).

5. The magnetic levitation balance based on a three-actuator structure according to claim 4, characterized in that, Each of the magnetic levitation rotors (212) includes: A rotor tray (2125); A connecting rod (2123), vertically threadedly connected inside the rotor tray (2125); A rotor permanent magnet mounting cover (2121), passing through the top of the connecting rod (2123) and threadedly connected to the rotor tray (2125); A rotor permanent magnet (2122), sleeved on the top of the connecting rod (2123) and rotationally connected inside the rotor permanent magnet mounting cover (2121) through a bearing (2124); the rotor permanent magnet (2122) and the corresponding stator permanent magnet (2114) are located on the same vertical axis.

6. The magnetic levitation balance based on the three-actuator structure according to claim 5, characterized in that, The balance main body housing (1) includes: A square aluminum frame (11), the square aluminum frame (11) includes four vertically arranged first aluminum beams (111), second aluminum beams (112) horizontally connected between the first aluminum beams (111), and square corner pieces (113) connected between the ends of the first aluminum beams (111) and the second aluminum beams (112); The aluminum alloy panel (12) is hermetically embedded in the face of the square aluminum profile frame (11), and a sample window for placing and taking samples is opened on the aluminum alloy panel (12). The stator platform (13) is horizontally connected inside the square aluminum profile frame (11). The stator platform (13) includes an upper plate (131) for fixing the laser distance sensor (3) and a lower plate (132) for fixing the magnetic levitation stator (211). The laser distance sensor (3) is located between the upper plate (131) and the lower plate (132), and the magnetic levitation stator (211) is threadedly connected to the lower surface of the lower plate (132).

7. The magnetic levitation balance based on a three-actuator structure according to claim 6, characterized in that, The laser distance sensor (3) is vertically fixed on the upper plate (131) through a sensor fixing plate (31). The interference laser emitted by the laser distance sensor (3) is vertically emitted downward, passes through the light-transmitting hole on the lower plate (132) and the light-transmitting hole of the coil seat (2113), and irradiates onto the reflector located above the mover permanent magnet (2122), and returns along the original optical path to form interference for high-precision position measurement.

8. The magnetic levitation balance based on a three-actuator structure according to any one of claims 1-7, characterized in that The load tray (5) is an alumina load basket, and the connecting mechanism (6) is a sample hook.

9. The magnetic levitation balance based on a three-actuator structure according to claim 6, wherein, A vibration isolation pad is further provided at the bottom of the square aluminum profile frame (11).

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