CN116165932A - A magnetic levitation control circuit for a three-float instrument - Google Patents

Abstract

The invention discloses a magnetic suspension control circuit of a three-float instrument, wherein a digital signal processor circuit generates PWM square waves; the excitation generating circuit modulates the PWM square wave into a sine wave excitation signal, and outputs the sine wave excitation signal to the position detection bridge; the position detection bridge drives the magnetic suspension coil to work under the action of the sine wave excitation signal; the position detection bridge obtains an alternating voltage signal used for representing the position of the magnetic suspension coil, and outputs the alternating voltage signal to the signal processing circuit through the multi-path gating switch; the signal processing circuit converts the alternating voltage signal input by the position detection bridge into a direct current signal used for representing the position of the magnetic suspension coil; the digital signal processor circuit obtains a boost control signal according to the direct current signal; the stress application control circuit responds to the stress application control signal to provide suspension stress application for the magnetic suspension coil. The invention realizes localization and miniaturization of the magnetic suspension circuit of the three-floating instrument and rapid and precise control of the controlled object.

Description

A magnetic levitation control circuit for a three-float instrument

technical field

The invention belongs to the technical field of inertia, and in particular relates to a magnetic levitation control circuit for a three-float instrument.

Background technique

At present, the three-float instrument, as a high-precision inertial instrument, is widely used in the inertial navigation of ballistic missiles and launch vehicles at home and abroad. The three-float instrument mainly includes a three-float gyroscope and a three-float gyro accelerometer. The supporting technology of levitation and magnetic levitation. The function of the magnetic levitation system is to detect the position change of the float through the magnetic levitation coil, analyze the movement state and trend of the float, and generate a magnetic levitation pulling force by applying a direct current to the magnetic levitation coil, so as to control the float in the oil at the middle position of the jewel bearing, completely breaking away from the mechanism of the jewel bearing. contact, avoiding the disturbance torque caused by mechanical friction, thereby improving the accuracy of the three-floating instrument.

In the maglev control circuit of the three-floating instrument published publicly at present, the circuit principle needs to use imported foreign devices or imported chip domestically packaged devices as functional support, and some of the circuits can be replaced in situ with domestic fully domesticated chips, but The 7B698 chip that integrates the excitation generating circuit and the phase-sensitive demodulation circuit has no localized chips that can be replaced in situ or similar functions in China, and no domestic chip manufacturer can develop this chip. Therefore, the existing maglev control circuit of the three-floating instrument is faced with the problem that it cannot be directly replaced in situ with a domestically produced chip to achieve complete autonomous control.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects, provide a three-float instrument magnetic suspension control circuit, solve the technical problem that the existing three-float instrument magnetic suspension control circuit cannot be replaced in situ with a domestic chip, and the present invention realizes the domestic production of the three-float instrument magnetic suspension circuit. miniaturization and fast and precise control of the controlled object.

In order to realize the foregoing invention object, the present invention provides following technical scheme:

A magnetic levitation control circuit for a three-float instrument, including an excitation generating circuit, a position detection bridge, a multi-channel selector switch, a signal processing circuit, a digital signal processor circuit and an afterburner control circuit;

The digital signal processor circuit generates a PWM square wave, and outputs the square wave to the excitation generating circuit;

The excitation generating circuit receives the PWM square wave input by the digital signal processor circuit, modulates the PWM square wave into a sine wave excitation signal, and outputs the sine wave excitation signal to the position detection bridge;

The position detection bridge drives the magnetic levitation coil to work under the action of the sine wave excitation signal;

The position detection bridge obtains the AC voltage signal used to characterize the position of the magnetic levitation coil, and outputs the AC voltage signal to the signal processing circuit through the multi-channel selection switch;

The signal processing circuit converts the AC voltage signal input by the position detection bridge into a DC signal used to represent the position of the magnetic levitation coil, and outputs the DC signal to the digital signal processor circuit;

The digital signal processor circuit obtains the afterburner control signal according to the DC signal, and outputs the afterburner control signal to the afterburner control circuit;

The afterburner control circuit responds to the afterburner control signal and provides levitation afterburner for the magnetic levitation coil.

Further, the position detection bridge acquires multiple differential signals used to characterize the position of the magnetic levitation coil;

The digital signal processor circuit controls the gate switches of the multi-channel gate switches to be turned on and off in sequence, so that the differential signals of all channels are sequentially input into the signal processing circuit according to the set gate order.

Further, the signal processing circuit includes a differential amplifier circuit and a demodulation circuit; the differential amplifier circuit amplifies and performs difference processing on the gated differential signal to obtain a differentially amplified AC voltage signal, and the differential signal is determined by the position The AC voltage signal output by the two channels of the detection bridge is formed; the demodulation circuit includes a phase-sensitive demodulator and a low-pass filter circuit, and the phase-sensitive demodulator uses the sine wave excitation signal input by the excitation generation circuit as a reference signal, and the differential The amplified AC voltage signal is demodulated to obtain a full half-wave AC signal used to characterize the position of the magnetic levitation coil, and the low-pass filter circuit filters the full half-wave AC signal into a DC signal used to characterize the position of the magnetic levitation coil.

Further, the differential amplifier circuit is a domestic instrument amplifier ZSAD620TF, and the demodulation circuit is a domestic phase-sensitive demodulator LZX2.

Further, the digital signal processor circuit includes a system initialization module, a magnetic levitation position acquisition and processing module, a magnetic levitation force calculation module, a magnetic levitation force force execution module and an RS485 communication module;

The system initialization module is used to set the system clock, interrupt enable and multi-channel strobe switch enable;

The magnetic levitation position acquisition and processing module includes a PWM square wave generation module, an A/D conversion circuit and a multiplex switch control module; the A/D conversion circuit is used to convert the DC signal input by the signal processing circuit into a digital signal; the multiplexer The pass switch control module is used to control the gating of the multi-channel strobe switch;

The maglev force calculation module presets the digital range of the center position of the float, that is, the dead zone, and compares the digital signal with the preset dead zone to obtain the force control signal; the specific method is: if the digital signal is within the dead zone, consider The float is in the center position, no additional force is required; if the digital signal is greater than the upper boundary of the dead zone or the lower boundary of the dead zone of the cell, positive or negative force is required to pull the float to move into the dead zone; the force is determined according to the number When the signal exceeds the dead zone boundary, the difference value is dynamically adjusted. The larger the difference, the longer the boosting time in the boosting cycle, and the smaller the difference, the shorter the boosting time in the boosting cycle;

Executing the maglev booster module is used for PWM off-enabling and controlling the on-off of the booster switch; the booster control circuit provides the magnetic levitation coil with the PWM off-enable when the booster is suspended, and controls the booster control circuit through the GPIO port according to the booster control signal , input the booster current into the magnetic levitation coil to generate magnetic pulling force to center the float;

The RS485 communication module is used to communicate with external devices.

Further, the A/D conversion circuit is a built-in 12-bit A/D module in the digital signal processor circuit;

The digital signal processor circuit also includes an A/D input limiting circuit connected between the A/D conversion circuit and the signal processing circuit; the A/D input limiting circuit is composed of two switching diodes, which input the A/D conversion circuit The high voltage is clamped at 3.3V, and the input low voltage is clamped at 0V.

Further, the booster control circuit includes ≥10 booster switches, each booster switch is controlled by the booster control signal output from the I/O port of the digital signal processor circuit, and when the booster switch is turned on, the magnetic levitation coil and the DC The power is turned on, and the magnetic levitation afterburner is performed.

Further, the excitation generating circuit includes a band-pass filter circuit and a voltage follower;

The band-pass filter circuit is used to modulate the PWM square wave into a sine wave excitation signal, and the voltage follower is used to stabilize the sine wave excitation signal without being affected by the subsequent load;

The resistors and capacitors in the band-pass filter circuit are determined according to the parameters of the actual demanded sine wave excitation signal.

Further, the band-pass filter circuit is an active second-order band-pass filter;

The active second-order bandpass filter includes resistors R1, R2, R3 and capacitors C1, C2;

Assume that the actual required sine wave excitation signal parameters include amplification factor A _u , quality factor Q, center frequency f ₀ , bandwidth B _w , resistors R1, R2, R3 and capacitors C1 and C2 are calculated according to the following formula:

Wherein, C=C1=C2.

Further, the operational amplifier in the band-pass filter circuit is a four-channel integrated operational amplifier FX147BH(Z), and one channel of the FX147BH(Z) is used to form a voltage follower for the AC excitation signal;

The digital signal processor circuit adopts the domestic DSP controller JDSPF2812A, and the crystal oscillator JA120-30MHz is used as the clock source of the digital signal processor circuit, and the frequency division circuit in the digital signal processor circuit generates a 12kHz clock, which is determined by the event in the digital signal processor circuit The manager module EVA outputs a 12kHz PWM square wave;

There is an on-chip memory FLASH in the digital signal processor circuit, 9 sectors A, C~J are used to solidify the magnetic levitation control software, and sector B is dedicated to solidify the magnetic levitation parameters.

Compared with the prior art, the present invention has at least one of the following beneficial effects:

(1) The present invention creatively proposes a magnetic levitation control circuit for a three-float instrument, which replaces the imported or pseudo-domestic LVDT signal conditioner used in the current conventional scheme by a newly designed functional circuit, and realizes the control of all materials in the three-float instrument magnetic levitation control circuit Completely localized, getting rid of the dependence on imported devices and pseudo empty package devices;

(2) The magnetic levitation control circuit of the present invention can realize fast and accurate control to the position of the float of the three-float meter, especially the frequency of the excitation signal is determined by the frequency division circuit and the crystal oscillator of the digital signal processor circuit, and the high stability of the clock is given to the frequency of the excitation signal High stability, much higher than the excitation signal generated by the LVDT signal conditioner in the conventional scheme;

(3) The magnetic levitation control circuit of the present invention takes into account all the user needs of the prior art, and is compatible with existing tasks and multi-type three-float instrument magnetic levitation control circuits under the condition that the size of the printed board remains unchanged. It is suitable for multiple models and realizes shelf-type The productization of Sanfu Instrument has promoted the productization of Sanfu Instrument;

(4) The present invention achieves a very simplified design, because the newly designed functional circuit replaces the 7B698 chip and the power circuit package size becomes 3 times larger, and the circuit board space becomes a problem, by using four-channel integrated operational amplifier and digital signal processor circuit The built-in A/D conversion module replaces the single-chip/D conversion circuit, the multi-channel analog switch, and the digital signal processor circuit. The input signal is limited and so on.

Description of drawings

Fig. 1 is a structural block diagram of a fully localized three-float instrument maglev control circuit in an embodiment of the present invention;

Fig. 2 is a schematic flow chart of a magnetic levitation circuit control process in an embodiment of the present invention;

Fig. 3 is a schematic diagram of an active second-order bandpass filter in an embodiment of the present invention.

Detailed ways

The following describes the present invention in detail, and the features and advantages of the present invention will become more clear and definite along with these descriptions.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments. While various aspects of the embodiments are shown in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

In the currently available magnetic levitation technology schemes, many devices that are mentioned or not mentioned but necessary in the scheme are all imported devices or pseudo-empty package devices. The present invention replaces the imported or pseudo-domestic components used in the current conventional scheme with a newly designed functional circuit. The advanced LVDT signal conditioner performs excitation generation, signal demodulation, and DC signal output functions, and takes the lead in solving the problem that the bare core of the LVDT signal conditioner is limited by foreign technology.

The present invention provides a completely localized three-float meter magnetic levitation control circuit. Through the new design of the autonomous excitation signal generation circuit and the demodulation circuit, the imported chip or the pseudo-empty package chip is replaced by a functional circuit, which ensures the accuracy of the magnetic levitation control and Under the premise of reliability, the complete localization of the magnetic levitation circuit has been realized, and the problem of foreign chips being stuck has been solved. In addition, through streamlining the design, the magnetic levitation circuit has fewer components and a smaller volume, laying the foundation for the miniaturization of the three-floating instrument.

The present invention provides a magnetic levitation control circuit for a three-float instrument, comprising: an excitation generating circuit 1, a position detection bridge 2, a multi-channel selection switch 3, a signal processing circuit 4, a digital signal processor circuit 6 (integrated A/D conversion Circuit 5), afterburner control circuit 7, RS485 interface circuit 8;

Excitation generating circuit 1 is used to generate a sinusoidal excitation signal, which acts on the position detection bridge to drive the magnetic levitation coil to work; processing the 12kHz signal requires the operational amplifier to have a very high bandwidth, and generating a 12kHz AC signal with an amplitude of 1.6V further requires the operational amplifier It has a large slew rate, therefore, the band-pass filter circuit 9 can only use a domestically produced four-channel integrated operational amplifier FX147BH(Z). Aiming at the insufficient load capacity of the AC excitation signal of the band-pass filter circuit 9 , one of the channels of FX147BH(Z) is used to form a voltage follower 10 for the AC excitation signal, which greatly improves the load capacity of the excitation generating circuit 1 .

The position detection bridge 2 is used to detect the magnetic levitation voltage signal of each channel to represent the current position of the float of the three-float instrument;

The multi-channel gating switch 3 is used for channel gating of the magnetic levitation position signal, so as to realize the branch acquisition of the magnetic levitation signal;

The signal processing circuit 4 is used to amplify, demodulate and filter the collected position signal to form an analog signal to be converted;

The A/D conversion circuit 5 is used for analog-to-digital conversion of the processed position signal to obtain the digital signal of the magnetic levitation position; the A/D conversion circuit 5 is a 12-bit A/D integrated in the digital signal processor circuit 6 The converter replaces the single-chip A/D conversion circuit of the prior art, and the accuracy of the A/D conversion circuit 5 is better than that of the prior art through reference source correction and median filter processing.

The digital signal processor circuit 6 is the core control device of the circuit, which stores embedded software and magnetic levitation parameters, generates PWM, performs I/O control, calculation, communication and other functions. The digital signal processor circuit 6 is equipped with embedded software, which performs calculation and analysis of digital signals, performs maglev force control according to the calculation results, and sends position signals and force control signals to the host computer for monitoring through the RS485 interface circuit;

The afterburner control circuit 7 is used to respond to the control signal output by the digital signal processing circuit 5, and as an actuator, switch the DC power supply on and off the magnetic levitation coil by means of a control switch to realize the magnetic levitation afterburner; the afterburner control circuit 7 adopts an analog switch SF312MD, its The packaging size is three times that of the pseudo-empty package chip analog switch TW312SS in the prior art.

The RS485 interface circuit 8 is used for communication between the magnetic levitation control circuit and external equipment.

In the maglev control circuit of the above-mentioned three-floating instrument, the excitation generating circuit 1 is controlled by the digital signal processor circuit 6 to generate a PWM square wave, and the PWM square wave signal is converted into a target value after passing through the band-pass filter circuit 9 and the voltage follower 10. Sine wave excitation signal.

The position detection bridge 2 is a bridge circuit composed of resistors and coils, which can convert the coil inductance change caused by the position change of the float into an AC voltage signal to represent the position change of the magnetic levitation.

The multi-channel strobe switch 3 is used to sequentially select multiple channels of the maglev position signal, and can collect the maglev signals of each channel one by one according to requirements.

The signal processing circuit 4 is used to amplify, demodulate and filter the collected position signal to form an analog signal to be converted, and includes a differential amplifier circuit 11 and a demodulation circuit 12 . The differential amplifier circuit 11 amplifies and performs difference processing on the maglev differential signal of a positive and negative channel of a selected channel to obtain the amplified position signal; the demodulation circuit 12 includes two parts: a phase-sensitive demodulator and a low-pass filter circuit , where the phase-sensitive demodulator demodulates the differentially amplified position signal, takes the sinusoidal excitation signal output by the excitation generating circuit 1 as a reference signal, and demodulates to obtain a full half-wave AC signal representing the magnetic levitation position, and the low-pass filter circuit The full half-wave AC signal is filtered into a DC signal representing the position of the magnetic levitation.

The A/D conversion circuit 5 is a built-in integrated module of the digital signal processor circuit, responsible for converting the DC signal obtained by the signal processing circuit 4 into a digital signal, and inputting it into the digital signal processor circuit 6 for further calculation and processing.

The digital signal processor circuit 6 adopts the domestically produced DSP controller JDSPF2812A, and the present invention uses the crystal oscillator JA120-30MHz as the clock source of the digital signal processor circuit 6, and generates a 12kHz clock through the frequency division circuit in the digital signal processor circuit 6, which is generated by the digital signal The event supervisor module EVA in the processor circuit 6 outputs a 12kHz PWM square wave.

There is an on-chip memory FLASH in the digital signal processor circuit 6, and its sectors A, C~J are used to solidify the magnetic levitation control software, and its sector B is dedicated to the solidification of the magnetic levitation parameters. Memory resources of the signal processor circuit 6 .

The magnetic levitation control software is solidified in the digital signal processor circuit 6 to complete system initialization, PWM square wave generation, channel gating control, data acquisition of the A/D conversion circuit, magnetic levitation control law to calculate the force value, output force control signal, RS485 communication and other functions; the digital signal processor circuit 6 includes a total of five main functional modules: a system initialization module S1, a magnetic levitation position acquisition and processing module S2, a magnetic levitation force calculation module S3, a magnetic levitation force force execution module S4, and an RS485 communication module S5. Implement the following control process:

System initialization module S1: set system clock, enable interrupt, enable multi-channel strobe switch, read magnetic levitation parameters of sector B, etc.

Magnetic levitation position acquisition and processing module S2: PWM output enable, multi-channel strobe switch strobe control, A/D conversion, etc.

Magnetic levitation afterburner calculation module S3: Instruments in this field usually preset the digital value range of the center position of the float, which is called the dead zone. Compare the position digital quantity after sampling processing with the dead zone. If it is within the range of the dead zone, it is considered that the float is in the center position, and there is no need to execute force; Adding force in the positive or negative direction, pulling the float to move into the dead zone; the size of the boosting force is dynamically adjusted according to the difference beyond the boundary of the dead zone. The shorter the force time in the force cycle.

Executing the magnetic levitation booster module S4: including PWM off enable and control booster switch on and off. The magnetic levitation coil is both a detection mechanism and an actuator. It adopts a time-division multiplexing method, and both position acquisition and magnetic levitation force are realized through the coil. In order to avoid the superimposed interference caused by the excitation signal still being connected when the force is applied, the excitation needs to be disconnected, that is, the PWM is disabled; according to the calculation result of the force in S3, the force switch is controlled through the GPIO port, and the force current is input to ten maglev In the coil, a magnetic pull is generated to center the float.

RS485 communication module S5: Send communication data such as magnetic levitation position and afterburner data to the outside world.

The booster control circuit 7, each booster switch of which is controlled by the I/O port of the digital signal processor, controls the booster switch to conduct the booster switch through the booster value calculated according to the magnetic levitation control law, and provides the buoy with Magnetic levitation afterburner; the total number of channels of the afterburner control circuit 7 is not less than 10.

The magnetic levitation control circuit of the three-float instrument of the present invention is used for the control of the magnetic levitation bearing of the three-float instrument, and can also be used for the control and realization of other magnetic levitation bearings, and can be applied to the aviation and aerospace fields of high-precision navigation; all the components of the present invention can be completely autonomous. Control, to achieve 100% localization. The invention can get rid of the existing circuit's dependence on foreign technology and chips, and realize the localization and miniaturization of the magnetic levitation circuit of the three-floating instrument and the rapid and precise control of the controlled object.

Example:

Fig. 1 is a structural block diagram of a completely localized three-float instrument maglev control circuit in an embodiment of the present invention. In this embodiment, the maglev control circuit of the fully domesticated three-float meter includes: an excitation generating circuit 1, a position detection bridge 2, a multiplex switch 3, a signal processing circuit 4, and a digital signal processor circuit 6 integrated A/D conversion circuit 5, digital signal processor circuit 6, force control circuit 7, RS485 interface circuit 8.

The excitation generating circuit 1 includes a bandpass filter circuit 9 and a voltage follower 10 . According to the excitation signal parameters of actual demand, the resistance and capacitance of the corresponding resistance and capacitance values are configured, so that the band-pass filter circuit 9 modulates the PWM square wave signal generated by the digital signal processor circuit 6 into a required sine wave excitation signal, and the voltage follower 10 is used. Because the stable sinusoidal signal is not affected by the post-stage load.

In this embodiment, the digital signal processor circuit 6 is set by software to output a square wave signal of 3.3V and a duty cycle of 50% through the PWM pin after the initialization is completed; This value can be obtained through experience and calculation, and one of the preferred design methods is as follows:

Select the form of the band-pass filter circuit as an active second-order band-pass filter. According to the following formulas (1), formula (2), formula (3), and formula (4), it can be known that by adjusting the resistance R1 shown in Figure 3 , R2, R3 resistance and capacitance C (C=C1=C2) capacitance can obtain the required gain, bandwidth and excitation signal of Q value.

gain

Quality factor

Center frequency

bandwidth

According to the above-mentioned design method, the square wave signal can be converted into a sinusoidal excitation signal with an effective value of 1.6V and a frequency of 12KHz; the operational amplifier in the band-pass filter circuit 9 and the voltage follower 10 is preferably a four-way integrated operational amplifier.

The position detection bridge 2 is composed of a coil and a resistor, and can convert the coil inductance change caused by the position change of the float into an AC voltage signal. The implementation method is that the equivalent impedance of the excited inductance coil can be obtained according to the applied excitation signal, and the calculation method is as formula (5):

Equivalent impedance

By selecting the corresponding bridge arm resistance, the balance state of the electric bridge at the fixed position of the magnetic levitation float can be realized.

The multi-channel strobe switch 3 is used to strobe the position detection signals of the multiple channel coils of the maglev. The digital signal processor circuit 6 controls the multi-channel strobe switch 3 to turn on and off sequentially, and the maglev signals of each channel can be collected as required.

In this embodiment, ten magnetic levitation coils are set, and five differential signals are obtained through the position detection bridge 2; the multi-channel strobe switch 3 is preferably a domestic double 8-selection 1 analog switch, so that the five-channel signals are sequentially selected according to the set strobe sequence Enter the post-stage circuit.

The signal processing circuit 4 includes a differential amplifier circuit 11 and a demodulation circuit 12 . The differential amplifier circuit 11 amplifies and performs difference processing on the maglev differential signal of a positive and negative channel of a gate, and obtains the amplified position signal; the demodulation circuit 12 modulates the differentially amplified position signal to excite The sinusoidal excitation signal output by the generating circuit 1 is used as a reference signal, and demodulated to obtain a DC signal of the magnetic levitation position;

In this embodiment, the differential amplifier circuit 11 is preferably a domestic instrument amplifier, which has the characteristics of low cost and high precision, and the required amplification factor can be set by adjusting the resistance. In this embodiment, according to the overall gain of the system, the resistance value of the adjustment resistor is selected 9.1KΩ, the magnification is 5.5 times;

In this embodiment, the modem in the demodulation circuit 12 is preferably a domestic phase-sensitive demodulator, which has the characteristic of adjustable output zero; since the signal used for A/D conversion must be a DC signal, it also needs to be based on the selected phase. Sensitive demodulator type for adaptive adjustment, if the demodulated signal is DC, it can be directly used for A/D conversion; if the demodulated signal is AC, filter circuit can be set according to the signal condition to convert it to DC signal. In one case of this embodiment, the demodulated waveform is a half-wave AC signal, so a second-order low-pass filter circuit is designed to filter the waveform to obtain a corresponding DC signal.

The excitation generation circuit 1 and the signal processing circuit 4 (including the differential amplifier circuit 11 and the demodulation circuit 12) described in this embodiment realize the localization of the excitation generation and demodulation functions of foreign LVDT signal processors through independent circuit design Substitution solves the problem that the relevant device circuit cannot be localized.

The A/D conversion circuit 5 is used to perform analog-to-digital conversion on the processed DC position signal to obtain a magnetic levitation position digital signal;

In this embodiment, the aforementioned A/D conversion circuit 5 preferably uses a built-in 12-bit A/D module in the digital signal processor circuit 6, which reduces the use of peripheral chips and further reduces the circuit size and cost; according to the A/D conversion The input voltage of circuit 5 is required to be positive, and the adder circuit is designed by using the fourth operational amplifier of the aforementioned four-way operational amplifier to raise the demodulated DC signal to a constant voltage value;

In order to further protect the digital signal processing circuit 6, an A/D input limiter circuit consisting of two switching diodes is used in this embodiment to clamp the input high voltage at 3.3V and the input low voltage at 0V, avoiding excessive voltage or Too low negative voltage input damages the device.

The magnetic levitation control software is written in the digital signal processor circuit 6, and the position digital signal is calculated and analyzed to calculate the required force value, and the magnetic levitation force control is executed according to the calculation result, and the position signal and the force force are transmitted by the RS485 interface circuit. Control and other signals are sent out for monitoring;

The common package shape of the digital signal processor circuit 6 is a four-corner flat package LQFP. In this embodiment, the package form of the preferred digital signal processor circuit 6 is BGA, which is smaller than the conventional LQFP package volume; and by adjusting the pin ordering of the device, by The back shape is changed to a 16*16 array arrangement, further optimizing the BGA package shape, which reduces the size by one-third compared with the conventional surface mount package, which is conducive to further reducing the circuit volume.

The afterburner control circuit 7 is used to respond to the control signal output by the digital signal processing circuit 6, and as an actuator, the power supply of the magnetic levitation coil is switched on and off by means of a control switch to realize the magnetic levitation afterburner; and its single-way switch is controlled by a single-way I/ O control, when the power is added, the single switch is turned on to allow the DC power to pass through, providing current for the single coil, and the total number of channels of the afterburner switch is not less than 10.

In this embodiment, the afterburner control circuit 7 selects three domestic four-way single-pole single-throw analog switches, which have the characteristics of controlling the four-way switches separately and having a large channel input current.

The RS485 interface circuit 8 is used for the communication between the magnetic levitation circuit and the upper computer.

Referring to Fig. 2, in this embodiment, the afterburner control circuit 7 includes: a system initialization module S1, a maglev position acquisition and processing module S2, a maglev afterburner calculation module S3, an execution maglev afterburner module S4, and an RS485 communication module S5 There are five main functional modules in total. Among them, the main loop in the program can be composed of S2 ~ S5 modules, which will be executed after the system is initialized.

System initialization module S1: set system clock, interrupt enable, multi-channel strobe switch enable, etc.

Magnetic levitation position acquisition and processing module S2: PWM output enable, multi-channel strobe switch strobe control, A/D conversion, etc.; in this embodiment, five maglev signals need to be collected, and the multi-channel strobe switch is controlled through the I/O port Strobe in turn to collect each position signal.

Magnetic levitation force calculation module S3: In this embodiment, the meter presets the digital value range of the center position of the float, which is called the dead zone, which can be set to 2048±8 for example. Compare the position digital quantity after sampling processing with the dead zone, if it is within the range of the dead zone, it is considered that the float is in the center position, and there is no need to apply force; if it is greater than the upper boundary of the dead zone (2056 in this example) or the dead zone of the community Lower boundary (2040 in this example), it is necessary to implement positive or negative afterburner to pull the float to move in the dead zone.

Execution of magnetic levitation afterburner S4 module: including PWM off enable and control on and off of afterburner switch. In this embodiment, the magnetic levitation coil is both a detection mechanism and an execution mechanism, and a time-division multiplexing method is adopted, and position acquisition and magnetic levitation force are both realized through the coil. In order to avoid the superimposed interference caused by the excitation signal still being connected when the force is applied, the excitation needs to be disconnected, that is, the PWM is disabled; according to the calculation result of the force in S3, the ten-way force switch is controlled through the GPIO port, and the force current is input to the ten-way In a magnetic levitation coil, a magnetic pull is generated to center the float.

RS485 communication S5 module: Send the magnetic levitation position and afterburner data to the upper computer.

The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent replacements, modifications or improvements can be made to the technical solutions and implementations of the present invention, all of which fall within the scope of the present invention. The protection scope of the present invention shall be determined by the appended claims.

The content that is not described in detail in the description of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. A three-float instrument maglev control circuit is characterized in that it comprises an excitation generating circuit (1), a position detection bridge (2), a multi-way strobe switch (3), a signal processing circuit (4), and a digital signal processing Device circuit (6) and afterburner control circuit (7); The digital signal processor circuit (6) generates a PWM square wave, and outputs the square wave to the excitation generating circuit (1); The excitation generating circuit (1) receives the PWM square wave input by the digital signal processor circuit (6), modulates the PWM square wave into a sine wave excitation signal, and outputs the sine wave excitation signal to the position detection bridge (2); The position detection bridge (2) drives the magnetic levitation coil to work under the action of the sine wave excitation signal; The position detection bridge (2) acquires an AC voltage signal used to characterize the position of the magnetic levitation coil, and outputs the AC voltage signal to the signal processing circuit (4) through a multiplex switch (3); The signal processing circuit (4) converts the AC voltage signal input by the position detection bridge (2) into a DC signal used to characterize the position of the magnetic levitation coil, and outputs the DC signal to the digital signal processor circuit (6); The digital signal processor circuit (6) obtains the booster control signal according to the DC signal, and outputs the booster control signal to the booster control circuit (7); The afterburner control circuit (7) responds to the afterburner control signal and provides levitation afterburner for the magnetic levitation coil. 2. a kind of three-float instrument maglev control circuit according to claim 1, is characterized in that, the position detection electric bridge (2) obtains the multi-channel differential signal that is used to characterize the maglev coil position; The digital signal processor circuit (6) controls the gate switches of the multi-channel gate switch (3) to be turned on and off in sequence, so that the differential signals of each channel are sequentially input into the signal processing circuit (4) according to the set gate sequence. 3. a kind of three floating instrument magnetic levitation control circuit according to claim 2, it is characterized in that, signal processing circuit (4) comprises differential amplifier circuit and demodulation circuit; Amplification and difference processing to obtain a differentially amplified AC voltage signal, wherein the differential signal is formed by the AC voltage signals output by two channels of the position detection bridge (2); the demodulation circuit includes a phase-sensitive demodulator and a low The phase-sensitive demodulator uses the sine wave excitation signal input by the excitation generating circuit (1) as a reference signal to demodulate the differentially amplified AC voltage signal to obtain a full half-wave AC signal used to characterize the position of the magnetic levitation coil. signal, the low-pass filter circuit filters the full half-wave AC signal into a DC signal used to characterize the position of the magnetic levitation coil. 4. The magnetic levitation control circuit for a three-float instrument according to claim 3, wherein the differential amplifier circuit is a domestic instrument amplifier ZSAD620TF, and the demodulation circuit is a domestic phase-sensitive demodulator LZX2. 5. A kind of three-float meter magnetic levitation control circuit according to claim 1, is characterized in that, comprises system initialization module, magnetic levitation position acquisition and processing module, magnetic levitation force calculation module, execution in the digital signal processor circuit (6) Magnetic levitation afterburner module and RS485 communication module; The system initialization module is used to set the system clock, interrupt enable and multi-channel strobe switch enable; The magnetic levitation position acquisition and processing module includes a PWM square wave generation module, an A/D conversion circuit (5) and a multi-channel strobe switch control module; the A/D conversion circuit (5) is used for direct The signal is converted into a digital signal; the multiplex switch control module is used to control the gate of the multiplex switch (3); The maglev force calculation module presets the digital range of the center position of the float, that is, the dead zone, and compares the digital signal with the preset dead zone to obtain the force control signal; the specific method is: if the digital signal is within the dead zone, consider The float is in the center position, no additional force is required; if the digital signal is greater than the upper boundary of the dead zone or the lower boundary of the dead zone of the cell, positive or negative force is required to pull the float to move into the dead zone; the force is determined according to the number When the signal exceeds the dead zone boundary, the difference value is dynamically adjusted. The larger the difference, the longer the boosting time in the boosting cycle, and the smaller the difference, the shorter the boosting time in the boosting cycle; Executing the maglev booster module is used for PWM off-enabling and controlling the on-off of the booster switch; the booster control circuit (7) provides the magnetic levitation coil with the PWM off-enable when the booster is suspended, and controls the booster through the GPIO port according to the booster control signal. The force control circuit (7) inputs the force current into the magnetic levitation coil to generate magnetic pulling force to center the float; The RS485 communication module is used to communicate with external devices. 6. a kind of maglev control circuit of three floating instruments according to claim 5, is characterized in that, A/D conversion circuit (5) is 12 A/D modules built-in in the digital signal processor circuit (6); The digital signal processor circuit (6) also includes an A/D input limiting circuit connected between the A/D conversion circuit (5) and the signal processing circuit (4); the A/D input limiting circuit consists of two switching diodes Composition, the high voltage input to the A/D conversion circuit (5) is clamped at 3.3V, and the input low voltage is clamped at 0V. 7. The magnetic levitation control circuit for a three-float instrument according to claim 1, characterized in that, the booster control circuit (7) includes ≥ 10 booster switches, and each booster switch is controlled by a digital signal processor circuit (6 ) is controlled by the booster control signal output by the I/O port. When the booster switch is turned on, the magnetic levitation coil is connected to the DC power supply, and the magnetic levitation booster is performed. 8. A kind of maglev control circuit for three-floating instrument according to claim 1, characterized in that, the excitation generating circuit (1) comprises a band-pass filter circuit (9) and a voltage follower (10); The band-pass filter circuit (9) is used for modulating the PWM square wave into a sine wave excitation signal, and the voltage follower (10) is used for stabilizing the sine wave excitation signal from being affected by the subsequent load; The resistors and capacitors in the band-pass filter circuit (9) are determined according to the parameters of the actual demanded sine wave excitation signal. 9. A kind of three-float instrument magnetic levitation control circuit according to claim 8, is characterized in that, band-pass filter circuit (9) is an active second-order band-pass filter; The active second-order bandpass filter includes resistors R1, R2, R3 and capacitors C1, C2; Assume that the actual required sine wave excitation signal parameters include amplification factor A _u , quality factor Q, center frequency f ₀ , bandwidth B _w , resistors R1, R2, R3 and capacitors C1 and C2 are calculated according to the following formula:

Wherein, C=C1=C2. 10. A kind of three floating instrument maglev control circuit according to claim 8, is characterized in that, the operational amplifier in the band-pass filter circuit (9) is four-channel integrated operational amplifier FX147BH (Z), uses FX147BH (Z) wherein 1 channel constitutes a voltage follower (10) for an AC excitation signal; The digital signal processor circuit (6) adopts domestically produced DSP controller JDSPF2812A, and the crystal oscillator JA120-30MHz is used as the clock source of the digital signal processor circuit (6), and a 12kHz clock is generated by the internal frequency division circuit of the digital signal processor circuit (6) , the PWM square wave of 12kHz is output by the event manager module EVA in the digital signal processor circuit (6); The digital signal processor circuit (6) has an on-chip memory FLASH, nine sectors A, C to J are used to solidify the magnetic levitation control software, and sector B is exclusively used to solidify the magnetic levitation parameters.

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