Electromagnetic dynamic pressure control mechanism for tea processing and tea rolling machine

Abstract

The invention relates to the technical field of tea rolling machines, and discloses an electromagnetic dynamic pressure control mechanism for tea processing and a tea rolling machine, a synchronous pulley type pressure adjustment driving structure is adopted, manual work can be replaced to realize automatic adjustment of pressure applied to a rolling cover, the adjustment accuracy of the pressure of the rolling cover can be improved while manpower is saved, and the production efficiency is improved. An FOC control algorithm is creatively adopted on the control of rolling pressure, accurate torque output and dynamic response capability can be realized, more accurate torque adjustment is achieved, the pressure of a rolling cover is detected in real time through a pressure sensor, pressure data is fed back to a control module, and through feedback control, the rolling effect is improved. The position of the rolling cover can be rapidly and accurately adjusted according to the actual pressure bearing condition of rolled leaves in the rolling barrel, dynamic pressure driving control is achieved, the finished product quality of tea leaves is improved, an FOC-controlled motor is small in size, integrated installation with an electronic control system is facilitated, closed-loop control is achieved through a sensor, the system integration degree is high, and the device is suitable for the design of a compact structure.

Description

Technical Field

[0001] The invention relates to the technical field of tea rolling machines, in particular to an electromagnetic dynamic pressure control mechanism for tea processing and a tea rolling machine. Background Art

[0002] Rolling is an important process in most tea processing. Except for white tea, other teas have rolling process in processing. Tea rolling, on the one hand, uses external force to roll the tea strips tightly to shape the handsome and compact appearance of tea, which is convenient for storage and brewing. On the other hand, it breaks the leaf cells, creating conditions for the contact between the substances contained in the tea and related chemical reactions such as oxidation, cracking, and condensation. The amount of leaves, rolling time, rolling pressure and rolling speed in the rolling process will directly affect the quality of tea. Especially for deeply fermented teas such as black tea, the importance of full rolling is emphasized. Rolling is mostly carried out through tea rolling machines. my country's traditional tea rolling machines are disc rolling machines, which are composed of rolling discs and frames, rolling barrels, rolling covers, columns, transmission mechanisms, etc. Under the condition that the speed of the rolling machine remains unchanged, pressure is the main factor that increases friction to make the leaves curl into strips and break cells. The size and adjustment of rolling pressure will directly affect the degree of tea strip formation and cell damage. Therefore, it is necessary to adjust the rolling pressure according to different rolling conditions.

[0003] At present, the tea rolling and pressurizing process is mostly manually operated. According to the state of the rolled leaves at different rolling moments, the hand wheel is turned in the working state of the rolling machine, and the nut and screw structure in the column drives the rolling cover to move up and down, thereby realizing pressurization or decompression of the withered leaves. The pressure is adjusted manually according to experience, or remotely according to experience. Due to different user experiences, the best rolling effect cannot be achieved. Therefore, an electromagnetic dynamic pressure control mechanism for tea processing and a tea rolling machine are proposed. Summary of the invention

[0004] The object of the present invention is to provide an electromagnetic dynamic pressure control mechanism for tea processing and a tea rolling machine to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: an electromagnetic dynamic pressure control mechanism, comprising a cantilever support, a kneading cover, a connecting pressure rod, a linear bearing and a pressure rod driving mechanism, wherein the connecting pressure rod is vertically movably mounted on the front part of the cantilever support through the linear bearing, and the kneading cover is mounted on the lower part of the connecting pressure rod;

[0006] A horizontal fixing plate is installed on the upper front side of the cantilever support, and the pressure rod driving mechanism is installed on the upper part of the horizontal fixing plate. The pressure rod driving mechanism is used to connect the downward pressure drive of the pressure rod. The pressure rod driving mechanism includes a first motor, a synchronous pulley, a synchronous toothed belt, a pressure rod connecting block and a control component. The synchronous toothed belt is vertically installed on the upper part of the horizontal fixing plate under the cooperative drive of the first motor and the synchronous pulley, and the upper end of the connecting pressure rod is fixedly installed with the synchronous toothed belt through the pressure rod connecting block;

[0007] The control component is used for driving and controlling the operation of the first motor, and the control component includes a pressure sensor, a signal transmitter, a display module, a control module and a drive module;

[0008] The pressure sensor is installed at the connection between the kneading cover and the connecting pressure rod to detect the real-time pressure applied by the pressure rod driving mechanism to the kneading cover;

[0009] The signal transmitter is used for conversion processing of control signals;

[0010] The display module is used to control the display of parameter information;

[0011] The control module is used for receiving and processing the sensing signal and outputting the driving signal;

[0012] The driving module is composed of a three-phase full-bridge circuit and is used for controlling the operation of the first motor.

[0013] Preferably, a bearing mounting hole is provided at the front of the cantilever support, the linear bearing is installed on the inner side of the bearing mounting hole, and the connecting pressure rod is slidably penetrated and inserted into the inner side of the shaft hole in the middle of the linear bearing.

[0014] Preferably, the kneading cover is disc-shaped, a connecting sleeve is installed at the lower part of the connecting pressure rod, and the kneading cover is installed at the bottom end of the connecting pressure rod through the connecting sleeve.

[0015] Preferably, the pressure sensor is installed inside the connecting sleeve, and the pressure sensor feeds back real-time data to the control module so as to accurately adjust and control the pressure.

[0016] Preferably, the horizontal fixed plate is fixedly mounted on the upper part of the cantilever support by bolts, a vertical mounting plate is fixedly mounted on the upper part of the horizontal fixed plate, the synchronous pulleys are arranged in pairs, two groups of the synchronous pulleys are rotatably mounted on the upper and lower sides of the edge of the vertical mounting plate at a fixed interval through a rotating shaft, the synchronous toothed belts are mounted on the upper part of the two groups of synchronous pulleys, and an electromagnetic brake is installed on the rear part of the upper synchronous pulley.

[0017] Preferably, the first motor is fixedly mounted on the lower rear part of the vertical mounting plate, the synchronous pulley on the lower side is fixedly mounted on the rotating shaft end of the first motor, a synchronous belt clamp is provided in the middle part of the synchronous toothed belt, the upper part of the pressure rod connecting block is fixedly mounted on the middle part of the synchronous toothed belt through the synchronous belt clamp and the bolts, and the upper end of the connecting pressure rod is fixedly mounted on the lower part of the pressure rod connecting block through bolts.

[0018] Preferably, the control module includes an MCU control unit. When the control module is working, the current sampling circuit feeds back the three-phase current to the MCU control unit, implements PI regulation in the MCU control unit and outputs the control signal to the drive module. The drive module is composed of a three-phase full-bridge circuit, outputs 6 PWM waves, drives the first motor after isolation and power amplification, and transmits the electromagnetic torque to the kneading cover by the pulley transmission structure to realize kneading pressure control.

[0019] Preferably, the above-mentioned method of implementing PI regulation in the MCU control unit is: the MCU control unit further analyzes the first motor by performing a mathematical model, and the specific analysis process is:

[0020] BLDC mathematical model in three-phase stationary coordinate system:

[0021]

[0022] where u A ,u B ,u C is the three-phase voltage of the stator winding; i A ,i B ,i C is the three-phase current; A ,ψ B ,ψ C It is the three-phase flux of the winding; in order to simplify the control process, the FOC vector control algorithm is adopted, thereby realizing the control idea of ​​the AC motor like a DC motor;

[0023] The two major transformations of FOC algorithm coordinates are: CLARK transformation and PARK transformation, which establish the BLDC in synchronous rotating coordinates to obtain the mathematical model of BLDC in the dq axis;

[0024] The coordinate transformation from the three-phase stationary coordinate system, that is, the ABC coordinate system to the stationary coordinate system α-β is called the CLARK transformation. The voltage expression of the αβ axis after the CLARK transformation is:

[0025]

[0026] The coordinate transformation of the stationary coordinate system α-β to the synchronous rotating coordinate system dq is the PARK transformation. The expression of the dq axis voltage after the PARK transformation is:

[0027]

[0028] After CLARK and PARK transformation, the original three-phase voltage equation is simplified to the dq axis voltage equation in the rotating coordinate system, where θ is the rotor electrical angle; considering the relationship between magnetic flux and current and the derivative relationship of the rotating coordinate system, the dq axis voltage equation in the two-phase rotating coordinate system is finally obtained:

[0029]

[0030] Among them, ω e is the rotor electrical angular velocity, ψ q ,ψ d is the dq axis flux, and the equation is:

[0031] ψ d =L d i d +ψ f

[0032] ψ q =L q i q

[0033] ψ f is the magnetic field chain of the permanent magnet, which is a constant value;

[0034] Substituting into the previous formula, we get:

[0035]

[0036] Finally, the stator voltage component u in the dq coordinate system is obtained d ,u q expression;

[0037] BLDC torque equation:

[0038]

[0039] Mechanical equation of motion, T L is the load, J is the moment of inertia;

[0040]

[0041] From the torque equation, we can know that the electromagnetic torque is related to the pole pair number p and the dq axis current i d ,i q ; The dq axis inductance is related to the permanent magnet flux;

[0042] Select i d = 0, in order to make all current components used to generate torque and avoid wasting d-axis current on flux linkage;

[0043] Under this strategy, the voltage equation in the dq coordinate system is further obtained:

[0044] u d =-ω e L q i q

[0045]

[0046] The q-axis current regulator parameters are used for adjustment; e ω of the component e ψ f Remove it, and we get:

[0047]

[0048] The Laplace transform of the dynamic voltage equation is easy to obtain:

[0049] U q (s) = RI q (s)+L q i q (s)

[0050] Therefore, the q-axis voltage-current transfer function is:

[0051]

[0052] The q-axis current loop structure block diagram is obtained by this design, and then the simplified current loop structure block diagram is obtained by simplification;

[0053] The open-loop transfer function of the current loop after correction by the PI regulator is:

[0054]

[0055] make The current loop open-loop transfer function is modeled as a typical type I system:

[0056]

[0057] The open-loop transfer function of a typical type I system is:

[0058]

[0059] Compared with, where K is the system gain and T is the time constant of the system;

[0060] We can get:

[0061]

[0062] Compared with the typical I-order system dynamic performance index, KT=0.5;

[0063] From this, the parameters of the PI regulator can be derived:

[0064]

[0065] After adding PI control, we can get the system block diagram.

[0066] A tea kneading machine comprises a frame mechanism and a pressure control mechanism, wherein the pressure control mechanism comprises the above-mentioned electromagnetic dynamic pressure control mechanism, and the frame mechanism comprises a supporting frame, a kneading plate, a kneading barrel, a second motor and a supporting column, wherein the kneading plate is supported and installed on the upper part of the supporting frame, and a driving crank arm is installed on the upper part of the supporting frame, and the kneading barrel is movably installed on the upper part of the supporting frame under the support of the driving crank arm, and after installation, the kneading cover is located inside the kneading barrel, and a control box for installing control components is provided on the side of the supporting frame.

[0067] Preferably, the second motor is fixedly mounted on the side of the supporting frame, the supporting column is mounted on the driving shaft end of the second motor through a driving crank arm, a hand wheel is provided in the middle of the supporting column, the rear part of the kneading barrel is fixedly mounted on the lower support of the supporting column, the rear part of the cantilever support is fixedly mounted on the upper part of the supporting column, and a flap driving motor and a discharge flap are provided at the lower part of the kneading plate, and the discharge flap is flipped and mounted on the lower opening side of the kneading plate under the drive of the flap driving motor.

[0068] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0069] 1. A synchronous pulley type pressure adjustment drive structure is adopted. A first motor, a synchronous pulley and a synchronous toothed belt are arranged on the upper part of the cantilever support. The first motor is used as a driving structure to cooperate with the synchronous pulley and the synchronous toothed belt to drive the connecting pressure rod to rise and fall, which can replace manual work to realize automatic adjustment of the pressure applied to the kneading cover. The moving distance of the connecting pressure rod can be adjusted more accurately to achieve precise pressure adjustment. While saving manpower, the adjustment accuracy of the kneading cover pressure can be improved, which is beneficial to the improvement of tea quality. The driving structure has a compact layout and reliable operation, and can be perfectly adapted and installed with the kneading machine.

[0070] 2. Creatively adopt FOC control algorithm in the control of kneading pressure. The core of FOC torque control is to project the three-phase current of the motor into a coordinate system aligned with the direction of the rotor magnetic field, thereby realizing the decoupling control of the motor current, magnetic field and torque, making the motor control similar to the performance of a DC motor. Through the decoupling control of the d-axis and q-axis currents, accurate torque output and dynamic response capabilities can be achieved, achieving more precise torque regulation. Compared with pneumatic and hydraulic systems, this system uses FOC control algorithm in motor torque control, which has the advantages of efficient and accurate torque control, higher energy efficiency, low noise and low maintenance.

[0071] 3. A pressure sensor is set at the connection between the kneading cover and the connecting pressure rod. The pressure of the kneading cover is detected in real time through the pressure sensor and the pressure data is fed back to the control module. Through feedback control, a stable torque output is maintained in a wide range of speeds. It is particularly suitable for scenarios that require precise and real-time torque control. During operation, the position of the kneading cover can be quickly and accurately adjusted according to the actual pressure-bearing conditions of the kneading leaves in the kneading barrel to achieve dynamic pressure drive control, thereby achieving flexible pressurization and improving the quality of the finished tea. The FOC-controlled motor is small in size, which is convenient for integrated installation with the electronic control system. Closed-loop control is achieved through sensors, and the system has a high degree of integration and is suitable for compact structure design. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0073] Figure 1 It is a schematic diagram of the overall front three-dimensional structure of the present invention;

[0074] Figure 2 It is a schematic diagram of the overall rear three-dimensional structure of the present invention;

[0075] Figure 3 It is a schematic diagram of the overall lower three-dimensional structure of the present invention;

[0076] Figure 4 It is a schematic diagram of the upper three-dimensional structure of the pressure control device of the present invention;

[0077] Figure 5 For the present invention Figure 4 Schematic diagram of the structure of the middle A area;

[0078] Figure 6 It is a schematic diagram of the three-dimensional structure of the lower side of the pressure control device of the present invention;

[0079] Figure 7 is a control system block diagram of the present invention;

[0080] Figure 8 It is a simulation schematic diagram of the FOC module of the present invention;

[0081] Fig. 9 It is a schematic diagram of BLDC closed-loop simulation of the present invention;

[0082] Fig.10 It is a schematic diagram of the three-phase current waveform of the present invention;

[0083] Fig.11 It is a schematic diagram of torque change of the present invention;

[0084] Fig.12 is a waveform diagram of an actual pressure sensor of the present invention;

[0085] Fig.13 The power input module circuit diagram of the present invention;

[0086] Fig.14 The step-down module circuit diagram of the present invention;

[0087] Fig.15 The A-phase inverter circuit diagram of the present invention;

[0088] Fig.16 It is the q-axis current loop block diagram of the present invention;

[0089] Fig.17 It is a simplified q-axis current loop block diagram of the present invention;

[0090] Fig.18 This is a block diagram of the software implementation of the present invention.

[0091] Explanation of the reference numerals in the accompanying drawings: 1. Cantilever support; 2. Kneading cover; 3. Connecting pressure rod; 4. Linear bearing; 5. Horizontal fixing plate; 6. First motor; 7. Synchronous pulley; 8. Synchronous toothed belt; 9. Pressure rod connecting block; 10. Synchronous belt clamp; 11. Pressure sensor; 12. Support frame; 13. Kneading plate; 14. Kneading barrel; 15. Second motor; 16. Support column; 17. Driving crank arm; 18. Hand wheel; 19. Flip cover driving motor; 20. Discharge flap; 21. Control box. DETAILED DESCRIPTION

[0092] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0093] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0094] Example

[0095] See also Figure 1-18 The present invention provides a technical solution: a tea rolling machine, including a frame mechanism and a pressure control mechanism, the frame mechanism includes a support frame 12, a kneading plate 13, a kneading barrel 14, a second motor 15 and a support column 16, the kneading plate 13 is supported and installed on the upper part of the support frame 12, the upper part of the support frame 12 is installed with a driving crank arm 17, the kneading barrel 14 is movably installed on the upper part of the support frame 12 under the support of the driving crank arm 17, the electromagnetic dynamic pressure control mechanism includes a cantilever support 1, a kneading cover 2, a connecting rod 16, a second motor 15 and a supporting column 16, the kneading plate 13 is supported and installed on the upper part of the support frame 12, the upper part of the support frame 12 is installed with a driving crank arm 17, the kneading barrel 14 is movably installed on the upper part of the support frame 12 under the support of the driving crank arm 17, and the electromagnetic dynamic pressure control mechanism includes a cantilever support 1, a kneading cover 2, a connecting rod 16, a second motor 15 and a supporting column 16, the kneading plate 13 is supported and installed on the upper part of the support frame 12, and the second motor 15 and the supporting column 16 are connected. The pressure rod 3, the linear bearing 4 and the pressure rod driving mechanism, the second motor 15 are fixedly installed on the side of the supporting frame 12, the supporting column 16 is installed on the driving shaft end of the second motor 15 through the driving crank arm 17, and a hand wheel 18 is provided in the middle of the supporting column 16. The rear part of the kneading barrel 14 is fixedly installed with the lower support of the supporting column 16, and the rear part of the cantilever support 1 is fixedly installed on the upper part of the supporting column 16. After installation, the kneading cover 2 is located inside the kneading barrel 14, and cooperates with the kneading cover 2 to complete the kneading process of the tea leaves.

[0096] In order to facilitate the connection and installation of the linear bearing 4, as shown in the attached Figure 4 The cam 4 is provided with an upper and lower groups of linear bearings, which are respectively installed on the upper and lower sides of the front of the cantilever support 1 to guide the up and down movement of the connecting pressure rod 3. The connecting pressure rod 3 is the component that actually applies pressure. The connecting pressure rod 3 can realize up and down movement through the transmission of the synchronous belt system to control the pressure applied to the tea leaves. The connecting pressure rod 3 slides through the inner side of the shaft hole installed in the middle of the linear bearing 4. The connecting pressure rod 3 is vertically movably installed on the front of the cantilever support 1 through the linear bearing 4. There are balls in the linear bearing 4 to reduce the friction of the connecting pressure rod 3 during movement. At the same time, the upper and lower groups of linear bearings 4 can ensure that the connecting pressure rod 3 moves smoothly in the vertical direction, which helps to improve the uniformity of kneading. The kneading cover 2 is disc-shaped and is used to apply actual kneading pressure to the tea leaves in the kneading barrel. In order to facilitate the connection and installation of the kneading cover 2 and the connecting pressure rod 3, as shown in the attached figure Figure 4As shown, a connecting sleeve is installed at the lower part of the connecting pressure rod 3, and the kneading cover 2 is installed at the bottom end of the connecting pressure rod 3 through the connecting sleeve. A flip cover driving motor 19 and a discharge flap 20 are provided at the lower part of the kneading plate 13. The discharge flap 20 is flipped and installed on the lower opening side of the kneading plate 13 under the drive of the flip cover driving motor 19, and can automatically complete the opening and closing of the discharge port.

[0097] In order to install and support the pressure rod drive mechanism, as shown in the attached Figure 4 As shown, a horizontal fixing plate 5 is installed on the upper front side of the cantilever support 1, and the horizontal fixing plate 5 is fixedly installed on the upper part of the cantilever support 1 by bolts. The horizontal fixing plate 5 is the horizontal reference plane of the entire installation structure, which is parallel to the kneading cover 2, ensuring that all components installed thereon can be accurately aligned in the vertical direction. The pressure rod driving mechanism is installed on the upper part of the horizontal fixing plate 5, and the pressure rod driving mechanism is used to connect the downward drive of the pressure rod 3. The pressure rod driving mechanism includes a first motor 6, a synchronous pulley 7, a synchronous toothed belt 8, a pressure rod connecting block 9 and a control component. In order to facilitate the connection and installation of the first motor 6, a vertical mounting plate is fixedly installed on the upper part of the horizontal fixing plate 5. The vertical mounting plate is an installation attachment structure for key components such as the first motor 6 and the synchronous pulley 7. , and at the same time provide a range limit for the stroke of the connecting pressure rod 3. The synchronous pulleys 7 are arranged in pairs. The two sets of synchronous pulleys 7 are respectively rotatably installed on the upper and lower sides of the edge of the vertical mounting plate through the rotating shaft at a fixed interval. The synchronous toothed belt 8 is installed on the upper part of the two sets of synchronous pulleys 7. The synchronous toothed belt 8 is an S3M synchronous belt, which transmits power from the driving source motor to the load end through the synchronous pulley 7. The S3M synchronous belt has flat-top semicircular arc teeth and belongs to the STD high-torque synchronous belt, which is commonly used in industrial torque transmission. It has a constant transmission ratio and high transmission efficiency. The synchronous pulley 7 is connected to the synchronous toothed belt 8 and drives it to operate, so that the pressure is transmitted in the vertical direction to achieve a uniform kneading effect. In order to improve the control accuracy, an electromagnetic brake is installed at the rear of the upper synchronous pulley 7.

[0098] The first motor 6 is a brushless DC motor, model 57BL95S06-210. The first motor 6 is the driving force source of the entire device, driving the synchronous belt system and outputting continuous and stable torque. The unique brushless structure of the brushless motor can effectively reduce motor loss and extend the life of the equipment. Figure 4As shown, the first motor 6 is fixedly mounted on the lower rear of the vertical mounting plate, and the lower synchronous pulley 7 is fixedly mounted on the rotating shaft end of the first motor 6. In this implementation, in order for the controller to effectively commutate the motor, the controller must always obtain accurate information about the rotor position. Since the birth of brushless motors, Hall effect sensors have been a popular choice for commutation feedback. In typical cases, three-phase control requires three sensors. Hall effect sensors for detecting rotor position are embedded in the motor stator, so that the transistors in the three-phase bridge can be switched to drive the motor. The outputs of the three Hall sensors are generally marked as U, V and W channels. However, this position feedback method has some disadvantages. The controller can only obtain partial information about the motor position from the Hall effect sensor. The three Hall sensors, in pairs, can only obtain 60° commutation information. Information within 60° cannot be obtained, which will cause problems in systems that require accurate position feedback to operate normally. In servo systems, traditional photoelectric encoders are usually used to obtain higher-precision angle information.

[0099] MT6701 is a magnetic angle sensor chip from MagnTek, which provides 14Bit, 0~360° single-turn absolute angle detection, and has multiple information output modes such as ABZ / PWM / analog / I2C / SSI. It can also provide non-contact press detection function according to the instantaneous change of magnetic field strength, which can replace traditional photoelectric encoders at a lower cost. It can be applied to absolute angle output, closed-loop stepper motor, BLDC motor rotation angle detection, robot joints, non-contact buttons, non-contact potentiometers and other occasions. In terms of installation, it is only necessary to install radial magnets on the axis of the shaft and fix the sensor circuit board. The BLDC vector control angle acquisition in this system is based on the application point of MT6701. BLDC with MT6701 has obvious advantages over PMSM in terms of cost and cost performance, especially in the mid-to-low-end market, where the application scenarios with less control accuracy requirements are simple, the BLDC motor has a simple structure, mature production process, and low control algorithm requirements. MT6701 can be used to replace traditional Hall sensors to further improve control performance. However, PMSM has a higher initial cost due to its more efficient sinusoidal wave control requirements and complex structural design, and is suitable for high-end markets with strict performance requirements.

[0100] In order to facilitate the driving connection with the connecting rod 3, as shown in the attached Figure 5As shown, a synchronous belt clamp 10 is provided in the middle of the synchronous toothed belt 8, and the upper part of the pressure rod connecting block 9 is fixed to the middle part of the synchronous toothed belt 8 by the synchronous belt clamp 10 and the bolts. After the pressure rod connecting block 9 is an L-shaped pressure plate and fixed with the synchronous belt clamp 10, the synchronous toothed belt 8 and the connecting pressure rod 3 are connected so that power can be transmitted to the connecting pressure rod 3. A long slot opening is provided at the bottom of the pressure rod connecting block 9. During installation, the position of the L-shaped pressure plate can be fine-tuned as needed to ensure that the tension and position of the synchronous belt are appropriate. The upper end of the connecting pressure rod 3 is fixed to the lower part of the pressure rod connecting block 9 by bolts.

[0101] Permanent magnet synchronous motor has good starting and speed regulation performance, and has no mechanical contact structure composed of commutator and brush, so it has the characteristics of long life, low noise, low electromagnetic interference, high control accuracy and large stall torque. In recent years, it has been widely used in various application requirements, such as various loads, constant loads and positioning applications in industrial control, automobiles, aviation, automation systems and other fields. Synchronous belt drive is a very efficient power transmission structure with a transmission efficiency of 0.98, compact structure, stable operation under harsh working conditions, extremely small elongation under tension, which can ensure the accuracy of tooth-slot meshing, reduce maintenance costs, no lubrication, and low operating costs. It is widely used in CNC machine tools, robots, automobiles and other industries, and is often used to transmit motor torque and provide traction to enable other mechanisms to reciprocate or continuously within a certain range of travel. It is an efficient and reliable torque transmission solution. By utilizing the performance advantages of permanent magnet synchronous motors, the tea rolling machine commonly used in tea processing plants is adaptively modified to achieve intelligent control of rolling time and pressure in tea rolling, thereby improving the efficiency and quality of tea rolling and reducing the degree of manual participation.

[0102] For drive control, as shown in the attached Figure 1 As shown, a control box 21 for installing a control component is provided on the side of the support frame 12. The control component is used for driving and controlling the operation of the first motor 6. The control component includes a pressure sensor 11, a signal transmitter, a display module, a control module and a drive module. Specifically:

[0103] The pressure sensor 11 is installed at the connection between the kneading cover 2 and the connecting pressure rod 3 to detect the real-time pressure applied by the pressure rod driving mechanism to the kneading cover 2. The pressure sensor 11 is installed inside the connecting shaft sleeve. The pressure sensor 11 feeds back real-time data to the control module so as to accurately adjust and control the pressure, thereby ensuring the stability and adjustability of the pressure during the kneading process.

[0104] The signal transmitter is used for the conversion and processing of the control signal, and the display module is used for the display and operation control of the control parameter information;

[0105] The control module is used for receiving and processing the sensor signal and outputting the drive signal. The control module includes an MCU control unit. When the control module is working, the current sampling circuit feeds back the three-phase current to the MCU control unit, implements PI regulation in the MCU control unit and outputs the control signal to the drive module. Specifically:

[0106] The machine that produces pressure on materials in industry is called a press. The motor used in industrial presses is often PMSM, a permanent magnet synchronous motor. Permanent magnet synchronous motors are also brushless DC motors, but the brushless DC motors usually refer to those that use centralized windings, and their back electromotive force is trapezoidal, also known as BLDC; while PMSM motors refer to those that use distributed stator windings and present sinusoidal back electromotive force. Brushless DC motors (BLDC) usually use trapezoidal control, and can also use field-oriented control (FOC); while PMSM motors usually only use field-oriented control. BLDC is essentially a permanent magnet synchronous motor with Hall position feedback that uses DC power input and uses an inverter to convert it into a three-phase AC power supply.

[0107] Trapezoidal control is also called "six-step commutation" because there are six steps of drive current required to complete one revolution of the rotor. In trapezoidal control, only two phases are active at a time. This method has a simple control algorithm, but the motor has torque pulsation at each commutation (60 degrees);

[0108] Although the back EMF of the BLDC motor is trapezoidal in theory, the inductance in the motor smoothes it into a sinusoidal shape. Sinusoidal control eliminates torque pulsation and provides smooth motion. The basic principle of sinusoidal commutation is to provide a sinusoidal current that varies according to the rotor position, with a current phase difference of 120 degrees. The control of sinusoidal commutation is achieved by using a field-oriented control algorithm. The basic principle of this algorithm is that the maximum torque is generated when the rotor and stator magnetic fields are orthogonal to each other. Therefore, the sinusoidal current will vary according to the rotor position to obtain maximum torque and smooth motion. To better understand the implementation process of this control method, further analysis can be performed by mathematically modeling the motor. Specifically:

[0109] BLDC mathematical model in three-phase stationary coordinate system:

[0110]

[0111] where u A ,u B ,u C is the three-phase voltage of the stator winding; i A ,i B ,i C is the three-phase current; A ,ψ B ,ψ Cis the three-phase flux of the winding; from the stator voltage equation of the three-phase stationary coordinate system, it can be seen that the variables except the stator resistance R are all AC quantities. The basic idea of ​​the FOC vector control algorithm is to convert the AC motor into an equivalent DC motor model, thereby simplifying the control process; in the DC motor structure, the motor torque is proportional to the armature current, and the control is relatively simple; in the AC motor, since the current and voltage are both AC quantities and they rotate continuously in space at the synchronous speed, the control is more complicated; the FOC algorithm transforms the motor phase voltage in the three-phase stationary coordinate system into a rotating coordinate system that is stationary relative to the rotor magnetic pole axis through coordinate transformation, thereby realizing the control idea of ​​the AC motor like a DC motor;

[0112] The two major coordinate transformations of the FOC algorithm are: stationary coordinate transformation (CLARK transformation) and synchronous rotating coordinate transformation (PARK transformation). The BLDC is established in the synchronous rotating coordinate to obtain the mathematical model of the BLDC in the dq axis;

[0113] The coordinate transformation from the three-phase stationary coordinate system, that is, the ABC coordinate system to the stationary coordinate system α-β is called the CLARK transformation. The voltage expression of the αβ axis after the CLARK transformation is:

[0114]

[0115] The coordinate transformation of the stationary coordinate system α-β to the synchronous rotating coordinate system dq is the PARK transformation. The expression of the dq axis voltage after the PARK transformation is:

[0116]

[0117] After CLARK and PARK transformation, the original three-phase voltage equation is simplified to the dq axis voltage equation in the rotating coordinate system, where θ is the rotor electrical angle; considering the relationship between magnetic flux and current and the derivative relationship of the rotating coordinate system, the dq axis voltage equation in the two-phase rotating coordinate system is finally obtained:

[0118]

[0119] Among them, ω e is the rotor electrical angular velocity, ψ q ,ψ d is the dq axis flux, and the equation is:

[0120] ψ d =L d i d +ψ f

[0121] ψ q =L q i q

[0122] ψ f is the magnetic field chain of the permanent magnet, which is a constant value;

[0123] Substituting into the previous formula, we get:

[0124]

[0125] Finally, the stator voltage component u in the dq coordinate system is obtained d ,u q expression;

[0126] BLDC torque equation:

[0127]

[0128] Mechanical equation of motion, T L is the load, J is the moment of inertia;

[0129]

[0130] From the torque equation, we can know that the electromagnetic torque is related to the pole pair number p and the dq axis current i d ,i q ; The dq axis inductance is related to the permanent magnet flux; Most BLDCs are surface mounted motors, with the permanent magnet attached to the rotor surface, and the dq values ​​are approximately equal;

[0131] Therefore, in the current control of surface-mount synchronous motors, it is usually chosen to set i d = 0, in order to make all current components used to generate torque and avoid wasting d-axis current on flux linkage;

[0132] Under this strategy, the voltage equation in the dq coordinate system is further obtained:

[0133] u d =-ω e L q i q

[0134]

[0135] The q-axis and d-axis current inner loops have symmetry and similar system characteristics, so the current regulator parameter tuning process is similar. In engineering, the q-axis current regulator parameter tuning is usually taken as an example.

[0136] When the motor is moving, the speed changes very slowly compared to the current change. For ease of analysis, the ω e ω of the component e ψ f Remove it, and we get:

[0137]

[0138] The Laplace transform of the dynamic voltage equation is easy to obtain:

[0139] U q (s) = RI q (s)+L q i q (S)

[0140] Therefore, the q-axis voltage-current transfer function is:

[0141]

[0142] Therefore, the q-axis current loop block diagram can be designed as shown in the attached figure. Fig.17 The block diagram structure shown is:

[0143] in is the reference value, T s For the current sampling period, the first block diagram is the system delay, the second is a PI controller; the third is the PWM control link, and the fourth is the q-axis transfer function;

[0144] Current sampling period T s Very small, replace the two small inertia links with one inertia link, and merge them At the same time, the PI controller is converted into a zero-pole form

[0145] Therefore, the current loop structure diagram can be simplified as shown in the attached figure. Fig.18 The block diagram structure shown is:

[0146] The open-loop transfer function of the current loop after correction by the PI regulator is:

[0147]

[0148] make The current loop open-loop transfer function is modeled as a typical type I system:

[0149]

[0150] The open-loop transfer function of a typical type I system is:

[0151]

[0152] Compared with, where K is the system gain and T is the time constant of the system;

[0153] We can get:

[0154]

[0155] Compared with the typical I-order system dynamic performance index, KT = 0.5 is usually taken;

[0156] From this, the parameters of the PI regulator can be derived:

[0157]

[0158] After adding PI control, the system block diagram can be obtained, as shown in the attached figure. Figure 7 As shown, attached Figure 8-12 Schematic diagram of the system simulation and parameter waveforms.

[0159] The driving module is composed of a three-phase full-bridge circuit and is used for the working control of the first motor 6. The driving module is composed of a three-phase full-bridge circuit and outputs 6 PWM waves. After isolation and power amplification, the first motor 6 is driven. The electromagnetic torque is transmitted to the kneading cover 2 by the pulley transmission structure to realize the kneading pressure control. Specifically:

[0160] The circuit structure of the drive module includes:

[0161] Power input unit: as attached Fig.13 As shown, connect the external DC 24V power supply from the P13 terminal, connect the capacitor for smoothing and filtering, the D6 transient voltage suppression diode is used to protect the circuit from high voltage spikes or surge currents, the D14 Schottky diode prevents the reverse voltage generated by the inductor L1 from entering the main circuit when the power is turned off or the current changes, XF1 is a fuse, and the MOS tube bus 27VIN voltage passes through the resistor divider circuit and is connected to the STM32PB0 pin through ADPW, so that the STM32 can collect the bus voltage;

[0162] Step-down unit: as attached Fig.14 As shown, two step-down converter modules (XL1509-12 and XL1509-5) are used to reduce the input voltage from +27V to +12V and +5V. The circuit also includes filter capacitors, inductors and other protection components to stabilize the output voltage and protect the circuit. C1 and C2 form input filter capacitors, which are used to filter the +27V input voltage and reduce the high-frequency noise at the input end. C3 and C23 have the same function. L2 inductor is used to reduce current ripple. D3 Schottky diode is used to provide freewheeling protection to prevent the reverse voltage generated when the inductive load is powered off from damaging the converter. F1 fuse prevents overcurrent. D5 is a TVS (transient voltage suppression) diode for overvoltage protection.

[0163] Three-phase full-bridge MOSFET inverter circuit and current acquisition: There are three windings in the brushless motor, namely A, B, and C phase windings. The current in each winding has two directions, so the current direction in the three-phase motor has 3*2=6. By controlling the current direction in the three windings in the three-phase bridge circuit, the direction is changed according to a certain rule to achieve continuous operation of the three-phase motor. By controlling the different duty cycles of the PWM signal, the output voltage is changed to control the speed and torque of the motor;

[0164] A phase inverter unit: as attached Fig.15 As shown, the EG3012 chip is dedicated to brushless motor N-channel MOS tube driving. TIM1CH1 and CH1N are a pair of inverted level signals output by the STM32 timer to the on-off of a pair of N-channel MOSFET tubes behind the EG3012 driver. The drain of the upper bridge MOS tube is connected to the 27V voltage bus, and the lower bridge MOS tube is connected to the 0.05 ohm sampling resistor. When the lower bridge MOS tube is turned on, the sampling resistor starts to work and a voltage drop is generated on the resistor. The voltage drop is amplified by 4 times through the TLC2274 four-way amplifier. The bias voltage signal RVF is connected to the '+' input of the amplifier. The voltage is divided by the resistor to 1 / 2VCC = 1.65V. Finally, the amplifier output is connected to the voltage acquisition pin of the single-chip microcomputer. After the single-chip microcomputer performs calculation and restoration, the current value that originally passed through the sampling resistor can be obtained, providing three-phase current parameters for FOC calculation and completing the working control drive, as shown in the attached figure. Fig.16 The following is a block diagram of the system software implementation.

[0165] In summary, a synchronous pulley type pressure adjustment drive structure is adopted, and a first motor 6, a synchronous pulley 7 and a synchronous toothed belt 8 are arranged on the upper part of the cantilever support 1. The first motor 6 is used as a driving structure to cooperate with the synchronous pulley 7 and the synchronous toothed belt 8 to drive the connecting pressure rod 3 to rise and fall, which can replace manual operation to realize automatic adjustment of the pressure applied to the kneading cover 2, and can more accurately adjust the moving distance of the connecting pressure rod 3 to achieve precise pressure adjustment. While saving manpower, it can improve the adjustment accuracy of the kneading cover 2 pressure, which is beneficial to the improvement of tea quality. The drive structure has a compact layout and reliable operation, and can be perfectly adapted and installed with the kneading machine. The FOC control algorithm is creatively used in the control of the kneading pressure. The core of the FOC torque control is to project the three-phase current of the motor into a coordinate system aligned with the direction of the rotor magnetic field, thereby realizing the decoupling control of the motor current, magnetic field and torque, so that the control of the motor is similar to the performance of a DC motor. Through the decoupling control of the d-axis and q-axis currents, it can be realized The system has the advantages of efficient and accurate torque output and dynamic response capability, and more accurate torque regulation. Compared with pneumatic and hydraulic systems, the system uses FOC control algorithm in motor torque control, which has the advantages of high efficiency and accurate torque control, higher energy efficiency, low noise and low maintenance. A pressure sensor 11 is arranged at the connection between the kneading cover 2 and the connecting pressure rod 3. The pressure of the kneading cover 2 is detected in real time by the pressure sensor 11 and the pressure data is fed back to the control module. Through feedback control, a stable torque output is maintained in a wide range of speeds, which is particularly suitable for scenes requiring accurate and real-time torque control. When working, the position of the kneading cover 2 can be quickly and accurately adjusted according to the actual pressure-bearing condition of the kneading leaves in the kneading barrel, and dynamic pressure drive control can be realized, thereby realizing flexible pressurization and improving the quality of the finished tea. In addition, the motor controlled by FOC is small in size, which is convenient for integrated installation with the electronic control system. Closed-loop control is realized through sensors, and the system has high integration and is suitable for compact structure design.

[0166] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.

Claims

1. An electromagnetic dynamic pressure control mechanism, comprising a cantilever support (1), a kneading cover (2), a connecting pressure rod (3), a linear bearing (4) and a pressure rod driving mechanism, characterized in that: The connecting pressure rod (3) is movably mounted on the front part of the cantilever support (1) in a vertical shape through a linear bearing (4), and the kneading cover (2) is mounted on the lower part of the connecting pressure rod (3); A horizontal fixing plate (5) is installed on the upper front side of the cantilever support (1), and the pressure rod driving mechanism is installed on the upper part of the horizontal fixing plate (5). The pressure rod driving mechanism is used to connect the downward pressure drive of the pressure rod (3). The pressure rod driving mechanism includes a first motor (6), a synchronous pulley (7), a synchronous toothed belt (8), a pressure rod connecting block (9) and a control component. The synchronous toothed belt (8) is vertically installed on the upper part of the horizontal fixing plate (5) under the cooperative drive of the first motor (6) and the synchronous pulley (7). The upper end of the connecting pressure rod (3) is fixedly installed with the synchronous toothed belt (8) through the pressure rod connecting block (9); The control component is used for driving and controlling the operation of the first motor (6), and the control component comprises a pressure sensor (11), a signal transmitter, a display module, a control module and a drive module; The pressure sensor (11) is installed at the connection between the kneading cover (2) and the connecting pressure rod (3) to detect the real-time pressure applied by the pressure rod driving mechanism to the kneading cover (2); The signal transmitter is used for conversion processing of control signals; The display module is used to control the display of parameter information; The control module is used for receiving and processing the sensing signal and outputting the driving signal; The driving module is composed of a three-phase full-bridge circuit and is used for controlling the operation of the first motor (6).

2. The electromagnetic dynamic pressure control mechanism according to claim 1, characterized in that: The front part of the cantilever support (1) is provided with a bearing mounting hole, the linear bearing (4) is mounted on the inner side of the bearing mounting hole, and the connecting pressure rod (3) is slidably penetrated and inserted into the inner side of the shaft hole in the middle part of the linear bearing (4).

3. The electromagnetic dynamic pressure control mechanism according to claim 2, characterized in that: The kneading cover (2) is disc-shaped, and a connecting sleeve is installed at the lower part of the connecting pressure rod (3). The kneading cover (2) is installed on the bottom end of the connecting pressure rod (3) through the connecting sleeve.

4. The electromagnetic dynamic pressure control mechanism according to claim 3, characterized in that: The pressure sensor (11) is installed inside the connecting sleeve, and the pressure sensor (11) feeds back real-time data to the control module so as to accurately adjust and control the pressure.

5. The electromagnetic dynamic pressure control mechanism according to claim 4, characterized in that: The horizontal fixed plate (5) is fixedly mounted on the upper part of the cantilever support (1) by means of bolts, a vertical mounting plate is fixedly mounted on the upper part of the horizontal fixed plate (5), the synchronous pulleys (7) are arranged in pairs, two groups of the synchronous pulleys (7) are rotatably mounted on the upper and lower sides of the edge of the vertical mounting plate at a fixed interval through a rotating shaft, the synchronous toothed belt (8) is mounted on the upper part of the two groups of synchronous pulleys (7), and an electromagnetic brake is mounted on the rear part of the upper synchronous pulley (7).

6. The electromagnetic dynamic pressure control mechanism according to claim 5, characterized in that: The first motor (6) is fixedly mounted on the lower rear part of the vertical mounting plate, the synchronous belt pulley (7) on the lower side is fixedly mounted on the rotating shaft end of the first motor (6), a synchronous belt clamp (10) is provided in the middle part of the synchronous toothed belt (8), the upper part of the pressure rod connecting block (9) is fixedly mounted on the middle part of the synchronous toothed belt (8) by the synchronous belt clamp (10) and the matching bolts, and the upper end of the connecting pressure rod (3) is fixedly mounted on the lower part of the pressure rod connecting block (9) by bolts.

7. The electromagnetic dynamic pressure control mechanism according to claim 1, characterized in that: The control module comprises an MCU control unit. When the control module is in operation, a current sampling circuit feeds back three-phase current to the MCU control unit, PI regulation is implemented in the MCU control unit and a control signal is output to a drive module. The drive module is composed of a three-phase full-bridge circuit, outputs 6 PWM waves, drives a first motor (6) after isolation and power amplification, and transmits electromagnetic torque to a kneading cover (2) through a pulley transmission structure, thereby realizing kneading pressure control.

8. The electromagnetic dynamic pressure control mechanism according to claim 7, characterized in that: The way to implement PI regulation in the MCU control unit is: The MCU control unit further analyzes the first motor (6) by performing a mathematical model analysis, and the specific analysis process is as follows: BLDC mathematical model in three-phase stationary coordinate system: where u A ,u B ,u C is the three-phase voltage of the stator winding; i A ,i B ,i C is the three-phase current; A ,ψ B ,ψ C It is the three-phase flux of the winding; in order to simplify the control process, the FOC vector control algorithm is adopted, thereby realizing the control idea of ​​the AC motor like a DC motor; The two major transformations of FOC algorithm coordinates are: CLARK transformation and PARK transformation, which establish the BLDC in synchronous rotating coordinates to obtain the mathematical model of BLDC in the dq axis; The coordinate transformation that transforms the three-phase stationary coordinate system, that is, the ABC coordinate system, to the stationary coordinate system α-β is called the CLARK transformation. The voltage expression of the αβ axis after the CLARK transformation is: The coordinate transformation of the stationary coordinate system α-β to the synchronous rotating coordinate system dq is the PARK transformation. The expression of the dq axis voltage after the PARK transformation is: After CLARK and PARK transformation, the original three-phase voltage equation is simplified to the dq axis voltage equation in the rotating coordinate system, where θ is the rotor electrical angle; considering the relationship between magnetic flux and current and the derivative relationship of the rotating coordinate system, the dq axis voltage equation in the two-phase rotating coordinate system is finally obtained: Among them, ω e is the rotor electrical angular velocity, ψ q ,ψ d is the dq axis flux, and the equation is: ψ d =L d I d +ψ f ψ q =L q I q ψ f is the magnetic field chain of the permanent magnet, which is a constant value; Substituting into the previous formula, we get: Finally, the stator voltage component u in the dq coordinate system is obtained d ,u q expression; BLDC torque equation: Mechanical equation of motion, T L is the load, J is the moment of inertia; From the torque equation, we can know that the electromagnetic torque is related to the pole pair number p and the dq axis current i d ,i q ; The dq axis inductance is related to the permanent magnet flux; Select i d = 0, in order to make all current components used to generate torque and avoid wasting d-axis current on flux linkage; Under this strategy, the voltage equation in the dq coordinate system is further obtained: u d =-ω e L q i q The q-axis current regulator parameters are used for adjustment; e ω of the component e ψ f Remove it, and we get: The Laplace transform of the dynamic voltage equation is easy to obtain: U q (s)=RI q (s)+L q sI q (S) Therefore, the q-axis voltage-current transfer function is: The q-axis current loop structure block diagram is obtained by this design, and then the simplified current loop structure block diagram is obtained by simplification; The open-loop transfer function of the current loop after correction by the PI regulator is: make The current loop open-loop transfer function is modeled as a typical type I system: The open-loop transfer function of a typical type I system is: Compared with, where K is the system gain and T is the time constant of the system; We can get: Compared with the typical I-order system dynamic performance index, KT=0.5; From this, the parameters of the PI regulator can be derived: After adding PI control, we can get the system block diagram.

9. A tea rolling machine, comprising a frame mechanism and a pressure control mechanism, characterized in that: The pressure control mechanism comprises the electromagnetic dynamic pressure control mechanism described in any one of claims 1 to 8, and the frame mechanism comprises a supporting frame (12), a kneading plate (13), a kneading barrel (14), a second motor (15) and a supporting column (16); the kneading plate (13) is supported and installed on the upper part of the supporting frame (12); a driving crank arm (17) is installed on the upper part of the supporting frame (12); the kneading barrel (14) is movably installed on the upper part of the supporting frame (12) under the support of the driving crank arm (17); after installation, the kneading cover (2) is located inside the kneading barrel (14); and a control box (21) for installing control components is provided on the side of the supporting frame (12).

10. A tea rolling machine according to claim 9, characterized in that: The second motor (15) is fixedly mounted on the side of the support frame (12); the support column (16) is mounted on the driving shaft end of the second motor (15) through a driving crank arm (17); a hand wheel (18) is arranged in the middle of the support column (16); the rear part of the kneading barrel (14) is fixedly mounted on the lower support of the support column (16); the rear part of the cantilever support (1) is fixedly mounted on the upper part of the support column (16); a flap drive motor (19) and a discharge flap (20) are arranged at the lower part of the kneading plate (13); the discharge flap (20) is flipped and mounted on the lower opening side of the kneading plate (13) under the drive of the flap drive motor (19).

Images