CN113346818B - Servo control system and method for loading MSK signal of mechanical antenna - Google Patents

Abstract

The invention discloses a servo control system for MSK signal loading of a rotating permanent magnet mechanical antenna. The rotating permanent magnet mechanical antenna includes a magnetic source, a motor and a controller. According to the corresponding relationship between the motion control characteristics of the radiation source and the output characteristics of the mechanical antenna, The signal frequency and phase modulations are mapped as controls for the average rotational speed and instantaneous position, respectively, resulting in input references for the rotary servo system. Then, double closed-loop control is adopted for the rotational speed and current of the motor, and closed-loop control is also performed on the relative position of the motor. In this method, the relative position of the output is controlled in real time to ensure the additional phase change of each symbol period signal ±π/2; by indirectly controlling the output speed difference, the signal frequency difference meets the requirements of ±1/(4T _s ), and the MSK Loading of digitally modulated signals.

Description

Servo control system and method for loading MSK signal of mechanical antenna

technical field

The invention belongs to the field of servo control of permanent magnet synchronous motors, in particular to a relative position closed-loop control method for loading MSK signals of mechanical antennas.

Background technique

In the field of low-frequency electromagnetic communication, the existing low-frequency transmitting antennas are all electrically small antennas, which have problems such as low radiation efficiency, large volume and large transmitting power, which limit the wide application of low-frequency electromagnetic communication in related fields. Mechanical antenna is a new type of low-frequency electromagnetic signaling technology that directly excites electromagnetic waves by using electrical charges or magnetic moments of mechanical motion. According to different radiation materials and mechanical motion modes, mechanical antennas can be divided into technical systems such as vibrating electret, vibrating permanent magnet, rotating electret and rotating permanent magnet. Benefiting from the mature application of rare earth permanent magnet materials and rotary servo control technology in military and civilian fields, rotating permanent magnet mechanical antennas have become the focus of research in this field at home and abroad.

Since mechanical antennas involve multidisciplinary fields, according to the electromagnetic emission and information loading mechanism of mechanical antennas, in order to achieve efficient applications, their design, analysis and application will face a series of problems and challenges.

In order to improve the efficiency of power amplifiers, constant envelope modulation strategies such as frequency shift keying (FSK) and minimum frequency shift keying (MSK) are mainly used at present, which involve the frequency and phase control of the transmitted signal. Different from the existing electric small antenna, which needs to control the frequency and phase of the output voltage/current of the power amplifier through the modulator, the mechanical antenna can realize information loading by changing the motion state of the radiation source. However, it is necessary to map different modulation parameters to the state parameters of vibration or rotational motion, and perform corresponding motion excitation and control.

Due to the influence of inertia, the motion state of the radiation source cannot be abruptly changed, which requires the phase of the modulation waveform to be continuous, so the MSK digital signal modulation strategy is selected. At the same time, state errors such as the position (angle) and speed (rotation speed) of the radiation source will affect the modulation performance of the mechanical antenna. Therefore, it is necessary to study the corresponding relationship between the motion control characteristics of the radiation source and the output characteristics of the mechanical antenna, and realize the real-time control of the motion state of the radiation source based on this. In order to improve the transmission bandwidth and signal-to-noise ratio, for the above control process, it is required that the controlled state parameters can respond quickly and have no steady-state error. The core is to design and adopt an appropriate servo control strategy and its implementation system to improve vibration or rotation. The dynamic followability and load disturbance resistance of servo control can improve the dynamic and robustness of the system.

SUMMARY OF THE INVENTION

The invention proposes a relative position closed-loop control method for MSK signal loading of a rotating permanent magnet mechanical antenna, and realizes the motion state control of the radiation source of the mechanical antenna through a rotating servo control system, thereby realizing the loading of the MSK digital modulation signal.

The technical scheme adopted in the present invention is as follows:

A servo control system loaded with MSK signal of a mechanical antenna includes a control circuit and a power circuit, the control circuit controls the output voltage and current of the power circuit, the output end of the power circuit is connected to the motor of the mechanical antenna, and the control circuit include,

Position regulator, accept relative position given and relative position feedback, adjust output speed difference;

Speed regulator, accepts speed difference, basic speed and speed feedback, and adjusts output quadrature axis current given;

The quadrature axis current regulator accepts quadrature axis current given and quadrature axis current feedback, and outputs quadrature axis voltage given;

Direct axis current regulator, accepting direct axis current setting and direct axis current feedback, and outputting direct axis voltage setting;

The driving signal generator, according to the quadrature axis voltage given and the direct axis voltage given the drive signal of the output power circuit.

The relative position given above is obtained according to the corresponding relationship between the MSK code element signal and the rotation state of the motor.

The above-mentioned relative position feedback is obtained after subtracting the base angular velocity from the real-time rotational angular velocity of the motor through integral operation.

The above-mentioned rotational speed regulator, quadrature-axis current regulator and direct-axis current regulator are proportional-integral regulators.

The above-mentioned basic angular velocity is the angular velocity at which the motor runs stably before the MSK modulation signal is loaded, and the basic rotational speed is calculated according to the basic angular velocity.

Servo control method for MSK signal loading of mechanical antenna, including

Step 1: Sampling the three-phase current of the motor in the mechanical antenna and detecting the position of the motor;

Step 2: Calculate the quadrature axis and direct axis current feedback of the motor according to the three-phase current, and calculate the rotational speed feedback and angular velocity of the motor according to the position of the motor;

Step 3: Calculate relative position feedback according to the angular velocity of the motor;

Step 4: Adjust the difference between the relative position reference and the relative position feedback to obtain the speed difference;

Step 5: Adjust the difference between the speed difference, the sum of the base speed and the speed feedback to obtain the given quadrature axis current;

Step 6: Adjust the difference between the quadrature-axis current setting and the quadrature-axis current feedback, and the direct-axis current setting and the direct-axis current feedback to obtain the quadrature-axis voltage and the direct-axis voltage;

Step 7: Calculate and generate the switch driving signal according to the quadrature axis voltage and the direct axis voltage;

Step 8 uses the switch driving signal to drive the inverter to output the voltage signal for driving the motor in the mechanical antenna.

The adjustment method in the above steps 4, 5 and 6 is to use a proportional-integral regulator for adjustment.

In the above step 6, the driving signal is generated by using SVPWM.

The beneficial effect of the present invention is that the relative position closed-loop control method for MSK signal loading of the rotating permanent magnetic mechanical antenna proposed by the present invention is simple and easy to implement, and the corresponding relationship between the motion control characteristics of the radiation source and the output characteristics of the mechanical antenna is clear , which can change the frequency of the digital signal on the basis of ensuring the continuity of the signal phase. Through the closed-loop control of the relative position, speed and current of the motor, the phase position of the motor and the magnetic source is directly controlled, and the speed is indirectly controlled.

In order to make the above-mentioned features and advantages of the invention more obvious and easy to understand, the following embodiments are given and described in detail with the accompanying drawings as follows.

Description of drawings

Figure 1 is a basic schematic diagram of a rotating permanent magnet mechanical antenna.

Figure 2 is an additional phase network diagram of the MSK signal.

FIG. 3 is a schematic diagram of the corresponding relationship between the MSK signal and the motor speed and phase information.

Figure 4 is a waveform diagram of the actual motor rotation angular velocity change.

Fig. 5 is the control block diagram of the servo control system loaded by the MSK signal of the mechanical antenna.

FIG. 6 is a flow chart of servo control of the MSK signal loading of the mechanical antenna.

Detailed ways

In order to make the purposes and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described clearly and completely according to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

As shown in Figure 1, it is a basic schematic diagram of a rotating permanent magnet mechanical antenna. The rotating permanent magnet mechanical antenna includes a magnetic source 1, a motor 2 and a servo control system 3. The servo control system 3 drives the motor 2, and the motor 2 drives the magnetic source 1 to move, so as to realize the motion state of the magnetic source 1. control, excite low-frequency electromagnetic wave signals and realize information loading. The symbol data to be transmitted needs to be converted into the input given, according to the input given and the state feedback of the magnetic source 1 (that is, the rotor of the motor 2), combined with a certain control strategy, the servo control system 3 changes the voltage and the voltage of the motor 2 in real time. current, so as to adjust the output torque of the motor 2 in real time, so that the rotation state of the magnetic source 1 can track the input given in real time, generate the electromagnetic signal to be transmitted and realize the information loading. The magnetic source 1 includes a permanent magnet and a sheath, the permanent magnet is used to generate a required static strong magnetic field, and the sheath is a non-magnetically conductive material, which is used to reduce the mechanical stress of the permanent magnet when the permanent magnet rotates at a high speed. The motor 2 generates the electromagnetic torque required for the rotation of the magnetic source 1 .

As shown in Figure 2, it is the additional phase network diagram of the MSK signal, θ _k (t) is the additional phase function of the MSK signal, and T _s is the symbol period. The phase of the MSK signal is continuous, the frequency band utilization rate is high, and the frequency difference between the two frequencies of the signal is the minimum frequency difference Δf=1/(2T _s ). The magnitude of the additional phase of the MSK signal can be calculated according to the frequency difference. The additional phase function θ _k (t) is a linear equation whose slope is the rotation angular velocity difference:

In any symbol period T _s , if the symbol data to be transmitted is 1, then θ _k (t) linearly increases by π/2; if the symbol data to be transmitted is 0, then θ _k (t) linearly decreases Small π/2. From this relationship, draw an additional phase network diagram for all possible paths of θ _k (t) for the MSK signal.

As shown in Figure 3, it is a schematic diagram of the corresponding relationship between the MSK signal and the motor speed and phase information, θ _k is the relative position of the motor 2 and the magnetic source 1, ω _c is the basic angular velocity of the motor, ω ₁ and ω ₂ are respectively The corresponding rotational angular velocity when the modulation symbols are 1 and 0. It can be seen from the foregoing that the key to realizing digital modulation information loading is to map different modulation parameters to the state parameters of the motion of the radiation source. To realize the information loading of MSK, the frequency and phase modulations are mapped to control the average speed and instantaneous position, respectively. ω _c and θ _k have a certain mathematical relationship with the motor speed difference and the size of the symbol period. Since the MSK modulated signal always changes ±π/2 in its additional phase within a duration T _s of the symbol, when the symbol is 1, the phase of θ _k (t) increases linearly by π/2, when the symbol is 1 When 0, the phase of θ _k (t) decreases linearly by π/2. Therefore, for the motor, the control objective is: within T _s , the integral of the actual motor rotational angular velocity ω minus the unmodulated base angular velocity ω _c , that is, the relative position θ _k is ±π/2rad. According to the mathematical relationship Δω=θ _k /T _s , if θ _k increases by π/2rad within T _s , the corresponding motor rotational angular velocity is ω ₁ =ω _c +Δω=ω _c +2π/(4T _s ); if θ When _k decreases by π/2rad within T _s , the corresponding motor rotational angular velocity is ω ₂ =ω _c -Δω =ω _c -2π/(4T _s ).

As shown in Figure 4, it is a waveform diagram of the actual motor rotation angular velocity change, Δt ₁ is the rise time of the motor speed up, and Δt ₂ is the down time of the motor deceleration. In actual operation, the rotational angular velocity of the motor cannot be directly changed from ω ₁ to ω ₂ , and the rise time Δt ₁ of the motor rotational angular velocity increase Δω and the decrease time Δt ₂ of the rotational angular velocity decrease Δω are not consistent, which leads to the fact that at T θ _k in _s is not ±π/2rad, and the accumulated error will increase with time. Therefore, if the traditional speed-current double closed-loop control is used, the phase will be biased. The present invention proposes a relative position closed-loop control method, which uses the relative position θ _k of the motor 2 and the magnetic source 1 as a direct control variable. Real-time control The relative position θ _k is tracked given, ensuring that the output θ _k is ±π/2rad for each symbol period T _s .

As shown in FIG. 5 , it is a block diagram of the MSK signal loading control based on the vector control of the permanent magnet synchronous motor, showing the specific method of the controller 3 to drive the motor 2 to realize the relative position θ _k of the motor 2 and the magnetic source 1 control. The servo control system 3 includes a control circuit 31 and a power circuit 32 . The control circuit 31 , the power circuit 32 and the motor 2 together form a three-closed-loop control of relative position-speed-current to realize the speed of the motor 2 . and rotor position control.

According to a certain modulation method such as MSK modulation, the information loading module maps the input signal data to the motion state control signal of the radiation source as the given signal of the servo control system 3 , that is, the relative position given θ _k ^* . The modulation method adopts MSK modulation, and the signal data is 101010 as an example, and the waveform of the given relative position θ _k ^* is similar to a triangle wave. If the modulation symbol is 1, then θ _k ^* linearly increases by π within T _s /2rad; if the modulation symbol is 0, then θ _k ^* is given linearly reduced by π/2rad within T _s .

The relative position loop includes a position adjuster 311 that accepts a relative position reference θ _k ^* , and a relative position feedback θ _k . The difference between the given value θ _k ^* of the relative position and the feedback value θ _k is the relative position error, which is input to the position regulator 311 to obtain the rotational speed difference Δn as a part of the rotational speed loop input. According to the corresponding relationship between the MSK symbol signal and the rotation state of the motor 2, the given relative position θ _k ^* is obtained. After subtracting the base angular velocity ω _c from the real-time rotational angular velocity ω of the motor 2 , the relative position feedback θ _k is obtained through the operation of the integrator 3111 . The position detection module 319 (position sensor) on the motor 2 monitors the rotor position θ _r of the motor 2 in real time, and the rotational speed calculation module 3110 calculates the motor speed n in real time according to the rotor position θ _r and the time difference, and the real-time rotational angular velocity ω is determined by The measured speed n is converted.

The rotational speed loop includes a rotational speed regulator 312 that accepts rotational speed difference Δn, base rotational speed n _c , and rotational speed feedback n. After the superposition of the rotational speed difference Δn and the base rotational speed n _c , the rotational speed n ^* is given as the rotational speed loop. According to the corresponding relationship between the MSK signal and the motor speed and phase information, the speed difference Δn is obtained as 15/T _s , and the speed loop is given as n _c ±15/T _s . The rotational speed feedback n is detected and calculated in real time by the motor position detection module 319 and the rotational speed calculation module 3110 . The difference between the given value n ^* of the rotational speed and the feedback value n is the rotational speed error, which is input to the rotational speed regulator 312 to obtain the given quadrature-axis current i _q ^* .

The current loop includes a current regulator 313 and a current regulator 314, the current regulators accept the AC/DC axis current given i _q ^* , _id ^* , the AC axis current feedback i _q and the DC axis current _id , respectively. The permanent magnet synchronous motor _id = 0 vector control mode is adopted, the quadrature axis current given value i _q ^* is the output of the above speed loop, and the direct axis current given value _id ^* is 0. Real-time detection of the three-phase currents _ia , _ib , _ic of the motor 2 by the Hall current sensor, and according to the rotor position angle, through the coordinate transformation modules 317 (for example, Clark transformation) and 318 (for example, Park transformation), to obtain the quadrature axis current feedback value i _q and the direct axis current feedback value _id . The difference between the given values i _q ^* and _id ^* of the AC and DC axis currents and the _feedback values i _q and id is the current error, which is input to the current regulators 313 and 314 to obtain the given values of the AC axis voltage u _q ^* and The direct axis voltage is given u _d ^* .

The quadrature axis voltage given u _q ^* and the direct axis voltage given _ud ^* are transformed into three-phase static coordinates (αβ coordinates) after passing through the coordinate transformation module 315 (for example, Park inverse transformation), and then passed through the SVPWM module 316 obtains the on-off state timing sequence of the six switches, and outputs to the power circuit 32 .

The power circuit 32 includes a DC power supply U _dc and an inverter. The inverter 321 includes six switches, whose on-off state timing is determined by the output of the control part 31 . By turning on and off the six switching tubes, the direct current U _dc is converted into three-phase sinusoidal alternating currents u _a , _ub , _uc , so as to drive the motor 2 to rotate.

In order to ensure the speed conversion when the rotor position of the motor is at nπ/2, the phase of the motor is monitored and judged in real time. When the rotor of the motor is at 0 or π, the MSK modulation is switched on, which can ensure the phase continuity of the MSK signal.

The described servo control system changes the voltage and current of the driving motor in real time through the controller according to the input given and the state feedback of the magnetic source, combined with a certain servo control strategy, so as to adjust the output torque of the driving motor in real time, so that the magnetic source can be adjusted in real time. The rotation state tracks the input given in real time, generates the required electromagnetic signal and realizes the information loading.

FIG. 6 is a flow chart of the servo control of the mechanical antenna MSK signal loading, showing the specific steps of the servo control method.

Step 1: Sampling the three-phase current of the motor in the mechanical antenna and detecting the position of the motor;

Step 2: Calculate the quadrature axis and direct axis current feedback of the motor according to the three-phase current, and calculate the rotational speed feedback and angular velocity of the motor according to the position of the motor;

Step 3: Calculate relative position feedback according to the angular velocity of the motor;

Step 4: Adjust the difference between the relative position reference and the relative position feedback to obtain the speed difference;

Step 5: Adjust the difference between the speed difference, the sum of the base speed and the speed feedback to obtain the given quadrature axis current;

Step 6: Adjust the difference between the quadrature-axis current setting and the quadrature-axis current feedback, and the direct-axis current setting and the direct-axis current feedback to obtain the quadrature-axis voltage and the direct-axis voltage;

Step 7: Calculate and generate the switch driving signal according to the quadrature axis voltage and the direct axis voltage;

Step 8 uses the switch drive signal to drive the inverter to output the motor voltage signal in the drive mechanical antenna.

The adjustment method in the above steps 4, 5 and 6 is to use a proportional-integral regulator for adjustment.

In the above step 6, the driving signal is generated by using SVPWM.

Although the present invention has been disclosed as above with examples, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the appended patent application.

Claims (6)

1. The servo control system loaded by the MSK signal of the mechanical antenna is characterized by comprising a control circuit and a power circuit, wherein the control circuit controls the output voltage and current of the power circuit, the output end of the power circuit is connected with a motor of the mechanical antenna, the control circuit comprises,

the position regulator receives the relative position setting of the motor relative to the magnetic source and the relative position feedback of the motor relative to the magnetic source, and regulates the output rotating speed difference, wherein the relative position setting of the motor relative to the magnetic source is obtained according to the corresponding relation between the MSK code element signal and the rotating state of the motor;

the rotating speed regulator receives the rotating speed difference, the rotating speed of the motor which stably runs before loading the MSK signal and the rotating speed feedback, and regulates the given output quadrature axis current;

the quadrature axis current regulator receives quadrature axis current setting and quadrature axis current feedback and outputs quadrature axis voltage setting;

the direct-axis current regulator receives direct-axis current setting and direct-axis current feedback and outputs direct-axis voltage setting;

and the driving signal generator is used for outputting a driving signal of the power circuit according to the quadrature-axis voltage setting and the direct-axis voltage setting.

2. The mechanical antenna MSK signal loading servo control system of claim 1, wherein the relative position feedback of the motor with respect to the magnetic source is obtained by integral operation after subtracting the angular velocity of the motor during stable operation before loading the MSK signal from the real-time rotation angular velocity of the motor.

3. A mechanical antenna MSK signal loaded servo control system according to claim 2, wherein the position regulator, the rotational speed regulator, the quadrature current regulator and the direct current regulator are proportional integral regulators.

4. The servo control method for loading the MSK signal of the mechanical antenna is characterized by comprising

Step 1, sampling three-phase current of a motor in a mechanical antenna and detecting the position of the motor;

step 2, calculating quadrature axis and direct axis current feedback of the motor according to the three-phase current, and calculating rotating speed feedback and angular speed of the motor according to the position of the motor;

step 3, calculating the relative position feedback of the motor relative to the magnetic source according to the angular velocity of the motor;

step 4, adjusting a difference value fed back by a relative position of the motor relative to the magnetic source and a relative position of the motor relative to the magnetic source to obtain a rotation speed difference, wherein the relative position of the motor relative to the magnetic source is obtained according to a corresponding relation between the MSK code element signal and the motor rotation state;

step 5, adjusting the rotation speed difference, and obtaining the given quadrature axis current by the difference between the sum of the rotation speeds of the motor in stable operation before loading the MSK signal and the rotation speed feedback;

step 6, adjusting the difference between the quadrature axis current given value and the quadrature axis current feedback value, and the difference between the direct axis current given value and the direct axis current feedback value to obtain a quadrature axis voltage and a direct axis voltage;

step 7, calculating to generate a switch driving signal according to the quadrature axis voltage and the direct axis voltage;

and 8, driving an inverter to output a voltage signal for driving a motor in the mechanical antenna by using the switch driving signal.

5. The servo control method for loading the MSK signal on the mechanical antenna according to claim 4, wherein the adjusting method in step 4, step 5 and step 6 is adjusting by using a proportional-integral adjuster.

6. The servo control method for loading the MSK signal on the mechanical antenna according to claim 5, wherein the driving signal is generated by SVPWM in step 7.

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