A tensile direct drive control system and device for power line tensile testing

Abstract

The present application discloses a tension direct-drive control system and device for power cord tension testing, comprising a tension direct-drive mechanism, a tension sensor, a DSP control chip, and an IPM inverter circuit. Before the tension direct-drive mechanism exerts a direct tension on the power cord that reaches a preset tension value, a PWM control signal controls the IPM inverter circuit to perform a first inverter output, and the first inverter output is used to control the tension direct-drive mechanism to enter a low-speed mobile operating state. After the tension direct-drive mechanism exerts a direct tension on the power cord that reaches a preset tension value, a PWM control signal controls the IPM inverter circuit to perform a second inverter output, and the second inverter output is used to control the tension direct-drive mechanism to maintain a constant tension operating state. This solution can perform closed-loop control of mode switching of the tension direct-drive mechanism, achieves high measurement accuracy, and correspondingly improves system sensitivity and response speed, thereby eliminating the tension overshoot problem caused by system hysteresis in traditional power cord tension testing and avoiding the generation of explosive force.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of detection technology, and in particular to a tension direct-drive control system and device for power line tension testing. Background Art

[0002] The tension test of the power cord is a test method to verify the quality of the power cord. Usually, a tension direct drive mechanism is used to apply external force to the power cord, gradually tightening the power cord. Then the tension increases to the specified value and remains at the specified tension value for 1s. Then the tension is reduced to zero and repeated 25 times to obtain a test report for the power cord.

[0003] In related technologies, most of the tension drives that apply tension to the power cord use counterweight tests, which use a cam divider to control the rise and fall of the counterweight to generate tension on the power cord. This method has low time control accuracy and is not conducive to accurate testing. Another method is to connect a servo motor to a mechanical transmission mechanism, such as a servo motor driving a belt, a screw, or a reduction gearbox to apply tension to the power cord, and then use a sensor to detect the tension value. The detection process of this mechanical transmission mechanism cannot accurately control the motor. The connection between the motor and the mechanical structure will lead to poor system stability, and the mechanical transmission of the motor will suffer from loss, and the sensitivity and response speed will not be high. The force application process may cause explosive force that will damage the power cord. Summary of the Invention

[0004] The present application provides a tension direct-drive control system and device for power line tension testing, which solves the problems of low sensitivity and response speed of mechanical structure system detection and tension overshoot.

[0005] On the one hand, a tension direct drive control system for power line tension testing is provided, the system comprising a tension direct drive mechanism, a tension sensor, a DSP control chip, and an IPM inverter circuit; wherein the DSP control chip and the IPM inverter circuit constitute a direct drive closed-loop control to perform closed-loop control on the tension direct drive mechanism;

[0006] The IPM inverter circuit is connected to a rectified and filtered power input, and is used to output a three-phase drive voltage after inversion to act on the tension direct drive mechanism; the tension direct drive mechanism is connected to the tension sensor, and is used to obtain the tension value directly acting on the power line;

[0007] The DSP control chip is connected to the tension sensor and the two inverter outputs of the IPM inverter circuit, and is used to analyze the input tension value and the inverter output, determine the operating state of the tension direct drive mechanism, and output a PWM control signal acting on the IPM inverter based on the operating state;

[0008] Among them, before the direct pulling force of the tension direct drive mechanism on the power line reaches the preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform the first inverter output, and the first inverter output is used to control the tension direct drive mechanism to enter the low-speed moving operation state; after the direct pulling force of the tension direct drive mechanism on the power line reaches the preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform the second inverter output, and the second inverter output is used to control the tension direct drive mechanism to maintain a constant pulling force operation state.

[0009] Specifically, when the tension direct drive mechanism is in a low-speed moving operation state, the tension direct drive mechanism generates a linear traveling wave magnetic field on the motor mover through a speed sensorless vector control algorithm, which interacts with the excitation flux linkage of the motor stator permanent magnet, generating direct tension and tightening the power cord;

[0010] The DSP control chip performs coordinate transformation based on the collected two-way first inverter output to calculate the rotor electrical angle estimation value θ e , and calculates a first PWM control signal fed back to the IPM inverter circuit based on the rotor electrical angle estimation value.

[0011] Specifically, when the tension sensor detects that the direct tension generated by the tension direct drive mechanism reaches the preset tension value, the tension direct drive mechanism enters a blocking working state;

[0012] The DSP control chip switches to a tension feedback closed-loop control with a fixed electromagnetic space vector; by detecting the module length of the voltage space vector output by the second inverter, the second PWM control signal acting on the IPM inverter circuit is adjusted and output.

[0013] Specifically, the DSP control chip is also connected to a current detection and conditioning circuit and an isolation drive circuit; the current detection and conditioning circuit is connected to the two inverter outputs of the IPM inverter circuit, and is used to condition and detect the drive current i of the two inverter outputs. a and i b The DSP control chip receives the driving current through the ADC module, and calculates and outputs the PWM control signal according to the direct tension detected by the tension sensor;

[0014] The isolation drive circuit is connected between the DSP control chip and the IPM inverter circuit, and is used to perform voltage isolation on the output PWM control signal and drive the IPM inverter circuit.

[0015] Specifically, the direct drive closed-loop control includes a speed loop and a current loop, and the reference speed input of the speed loop is the real-time speed n of the motor rotor. ref, the first reference current i of the current loop sdref is 0;

[0016] The DSP control chip performs coordinate transformation based on the collected two-way first inverter output to calculate the rotor electrical angle estimation value θ e , and calculating a first PWM control signal fed back to the IPM inverter circuit based on the estimated value of the rotor electrical angle, including:

[0017] In the i-th cycle, the collected driving current i a and i b Perform fixed-point calculations and calculate the drive current i based on the phase relationship c ; i is a positive integer greater than 0;

[0018] Clark transformation is used to transform the driving current i of the three-phase inverter output a 、i b and i c Perform orthogonal coordinate transformation to convert the three-phase drive current from the as-bs-cs coordinate system to the intermediate drive current i in the α-β coordinate system sα and i sβ ;

[0019] Obtain the estimated value of the rotor electrical angle in the i-1th cycle, and use Park transformation to transform the intermediate drive current i in the α-β coordinate system sα and i sβ Perform the rotation coordinate transformation and convert it into the feedback current i in the dqn coordinate system sd and i sq ; Among them, i sd Feedback to the speed loop, i sq Feedback to the current loop;

[0020] Obtain the intermediate drive voltage V of the speed loop and current loop in the i-1th cycle proportional integral PI regulation output respectively sdref and V sqref , combined with the feedback drive current i in the i-th cycle sd and i sq , calculate and obtain the rotor electrical angle estimation value within the i-th cycle; wherein, the rotor electrical angle estimation value is used for Park transform and Park inverse transform calculation.

[0021] Specifically, after the calculation obtains the estimated value of the rotor electrical angle in the i-th cycle, the method further includes:

[0022] Based on the rotor electrical angle estimation value and the feedback drive current of the i-th cycle, the estimated speed n of the motor rotor is calculated, and based on the estimated speed n and the real-time speed n refThe difference is adjusted by PI to obtain the second reference current i of the speed loop. sqref The first reference current and the second reference current are respectively related to the intermediate drive current i sα and i sβ The difference is PI-adjusted, and the output is the intermediate drive voltage V in the dqn coordinate system. sdref and V sqref ;

[0023] Based on the intermediate driving voltage V sdref and V sqref As the inverse transformation input, the calculated rotor electrical angle estimation value is combined to perform Park inverse transformation to obtain the voltage space vector V of the i-th cycle sαref and V sβref ;

[0024] The voltage space vector V sαref and V sβref Perform space vector pulse width modulation (SVPWM) calculation to obtain the first PWM control signal; the first PWM control signal includes three PWM duty cycles.

[0025] Specifically, when the direct pulling force exerted by the tension direct drive mechanism on the power line reaches the preset pulling force value, the voltage space vector corresponding to the preset pulling force value is determined as a constant voltage space vector, and the rotor electrical angle estimation value is a reference electrical angle;

[0026] The direct tension detected by the tension sensor is used as the negative feedback input of the proportional integral differential PID negative feedback control system, the preset tension value is used as the system input, PID adjustment is performed based on the difference between the two, and the adjustment output is used as the modulus reference of the voltage space vector

[0027] Based on the reference electrical angle and the constant voltage space vector, SVPWM calculation is performed in combination with the size of the module length reference, and modulation is performed to obtain the second PWM control signal; the second PWM control signal includes 3 PWM duty cycles.

[0028] Specifically, the DSP control chip has a built-in event manager, and the event manager is used to perform dead-zone adjustment on the modulated output PWM control signal to obtain a corresponding space vector PWM control signal.

[0029] Specifically, the DSP control chip is further provided with a JTAG port, and the JTAG port is connected to a host computer via a JTAG emulator, and program control and data burning are performed via the host computer.

[0030] Specifically, the speed loop is the system outer loop, the current loop is the system outer loop, and the sampling period of the current loop is 10 times that of the speed outer loop; the current detection and conditioning circuit detects the two-phase drive current through a Hall current sensor.

[0031] In another aspect, a tension direct drive control device for a power cord tension test is provided, the device comprising a support frame, a power cord, a fixing bracket, a baffle, a fixing device, a tension sensor, a tension direct drive mechanism, a direct drive closed-loop controller, and a sliding clamping mechanism;

[0032] The tension direct drive mechanism is horizontally fixed on the support frame and connected to the tension sensor via a rigid connecting rod; the tension sensor is located on the sliding clamping mechanism and is located in the same horizontal direction as the tension direct drive mechanism;

[0033] The sliding clamping mechanism can drive the tension sensor to slide between the baffle and the tension direct drive mechanism;

[0034] The fixing bracket is installed on the side of the support frame, and the fixing device is fixedly placed on the top. The baffle is provided between the fixing device and the tension sensor, and a wire threading hole is opened in the center. The power cord is fixed to the fixing device and the tension sensor through the wire threading hole;

[0035] The tension direct drive mechanism is connected to the direct drive closed-loop controller. The DSP control chip and the IPM inverter circuit inside the closed-loop controller constitute a direct drive closed-loop control system to perform closed-loop control on the tension direct drive mechanism.

[0036] The beneficial effects brought about by the above technical solution include at least: the tension direct-drive control system provided in the embodiment of the present application adopts a direct-drive control mechanism as a power source, and there is no need to convert the rotational motion of the motor into linear motion, thus eliminating the mechanical power transmission mechanism, and directly using the direct tension of the tension sensor as the motor output and the direct tension acting on the power cord; and the direct-drive closed-loop control composed of the DSP controller and the IPM inverter circuit can perform closed-loop control of the mode switching of the tension direct-drive mechanism, which not only has higher measurement data accuracy, but also improves the sensitivity and response speed of the system accordingly, eliminating the tension overshoot problem caused by system hysteresis in traditional power cord tension testing devices and avoiding the generation of explosive force. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram and flow chart of the structure of the power cord tension testing platform provided in an embodiment of the present application;

[0038] Figure 2 This is a structural block diagram of a tension direct drive control system provided by an embodiment of the present application;

[0039] Figure 3 This is a structural block diagram of the low-speed mobile operation mode provided in an embodiment of the present application;

[0040] Figure 4 This is a flowchart of a process of modulating and outputting a first PWM control signal provided by an embodiment of the present application;

[0041] Figure 5 This is a structural block diagram of the constant operation mode provided by an embodiment of the present application;

[0042] Figure 6 This is a flowchart of the process of modulating and outputting the second PWM control signal provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0044] In this document, "plurality" refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates an "or" relationship between the associated objects.

[0045] Direct drive mechanism: A direct drive mechanism, also known as a direct drive mechanism, is a device whose power source is provided directly by the electric motor, without intermediate speed reduction mechanisms or transmission mechanisms such as gearboxes or belts. The corresponding motor is called a direct drive motor (DD motor for short). Because a lower-speed DD motor has higher torque than a motor of the same power, it is also called a torque motor or moment motor.

[0046] In related technologies, the tensile test for power cords is primarily based on Clause 25.15 of the national mandatory standard GB 4706.1-2005, "Safety of Household and Similar Electrical Appliances Part 1: General Requirements." The power cord tensile test requires that the specified tensile force be applied to the power cord in the most unfavorable direction for 25 times, without the use of explosive force, and each time lasting 1 second. Based on this requirement.

[0047] Based on this requirement, this application designs a power cord tension test platform. The tension test on this test platform is divided into the following steps:

[0048] 1. Securely fix the appliance and use the clamping part to fix the power cord of the appliance;

[0049] 2. The tension direct drive mechanism moves slowly to tighten the power cord, and then the tension rises to the specified value;

[0050] 3. Maintain the specified tension value for 1s;

[0051] 4. Reduce the tension to zero;

[0052] 5. Repeat the above steps 25 times.

[0053] Figure 1 The present invention provides a tensile direct drive control device for power cord tension testing, which includes a support frame 10, a fixed bracket 20, a fixing device 30, a tension sensor 40, a tension direct drive mechanism 50, a direct drive closed-loop controller 60, and a sliding clamping mechanism 70. The fixed bracket 20 is installed on the side of the support frame 10, on which a fixed fixing device 30 is placed, which is similar to a counterweight and is used to provide grip. There is a baffle 31 on the right side of the fixing device 30. The baffle 31 is mainly used to ensure that the fixing device 30 does not move. A wire threading hole is opened on the baffle 31, and the power cord 11 to be tested is fixed to the fixing device 30 through the wire threading hole. The other side of the power cord 11 is connected to the tension sensor 40, which is located on the slidable sliding clamping mechanism 70 and is used for movement detection during the tightening and loosening process of the power cord, thereby achieving free linear movement with low friction. The rigid connecting rod 51 of the tension direct drive mechanism 50 is connected to the tension sensor 40, which serves as a power source for generating direct tension and generates a linear tension on the power cord. The tension direct drive mechanism 50 is controlled by a connected closed-loop controller 60, which is used to receive the real-time tension value of the tension sensor 40 and is responsible for the switching control of the operating mode of the tension direct drive mechanism 50. The tension sensor 40 and the sliding clamping mechanism 70 in this solution are an integrated structure, and are at the same horizontal height as the tension direct drive mechanism 50 and the power cord. The DSP control chip and IPM inverter circuit mentioned in this solution are the internal circuits and control chips of the direct drive closed-loop controller 60.

[0054] Figure 2This is a block diagram of the tension direct-drive control system. It specifically includes a rectifier and filter circuit, an IPM inverter circuit, a tension direct-drive mechanism, a tension sensor, a (high-performance) DSP control chip, an isolated drive circuit, and current detection and conditioning circuits. The tension direct-drive mechanism and tension sensor are external components, while the remainder constitutes the direct-drive closed-loop controller. 220V AC power passes through the rectifier and filter circuits and is then input into the IPM inverter control circuit or IPM inverter module. This circuit receives the PWM control signal from the isolated drive circuit, performs frequency conversion modulation based on the PWM control signal, and then inverts the output. The three-phase drive voltage (or current) output by the inverter is used to drive the tension direct-drive mechanism, thereby controlling the motor to achieve a specific speed and torque output for testing. The direct output of the tension direct-drive mechanism bypasses transmission equipment, eliminating unnecessary intermediate losses. Therefore, the linear tension on the power cord detected by the tension sensor represents the actual output of the motor. The DSP control chip receives the tension value of the tension sensor in real time. The current detection and conditioning circuit includes a Hall current sensor to detect the inverter output of two of the three phases of the IPM inverter circuit. The inverter output uses the magnetic field oriented space vector (SVPWM) technology to obtain the IPM drive signal. The driving voltage of the drive signal is V a 、V b and V c , the corresponding driving currents are i a 、i b and i c In this scheme, the i a and i b Take this as an example to illustrate.

[0055] The DSP control chip in this solution controls the tension direct drive mechanism in two modes: a low-speed movement mode and a constant-tension mode. The switching thresholds between these two modes are determined based on the direct tension value detected by the tension sensor. Before the direct tension force exerted on the power cord by the tension direct drive mechanism reaches a preset value, a PWM control signal controls the IPM inverter circuit to generate a first inverter output, which is used to control the tension direct drive mechanism to enter a low-speed movement mode. After the direct tension force exerted on the power cord by the tension direct drive mechanism reaches a preset value, a PWM control signal controls the IPM inverter circuit to generate a second inverter output, which is used to control the tension direct drive mechanism to maintain a constant-tension mode. The tension direct drive mechanism is fully controlled by the inverter output. The DSP control chip and the IPM inverter circuit form a closed-loop direct drive control system, providing closed-loop control of the tension direct drive mechanism. The data acquisition, conversion, and deadband adjustment are described in the previous embodiment and will not be further elaborated here.

[0056] To sum up, the tension direct-drive control system provided in the embodiment of the present application adopts a direct-drive control mechanism as a power source. There is no need to convert the rotational motion of the motor into linear motion, which eliminates the mechanical power transmission mechanism. The direct tension of the tension sensor is directly used as the motor output and the direct tension acting on the power cord; and the direct-drive closed-loop control composed of the DSP controller and the IPM inverter circuit can perform closed-loop control of the mode switching of the tension direct-drive mechanism. Not only is the measured data accuracy higher, but the sensitivity and response speed of the system are also improved accordingly, eliminating the tension overshoot problem caused by system hysteresis in traditional power cord tension testing devices and avoiding the generation of explosive force.

[0057] The control of this system mainly adopts the speed sensorless vector control algorithm to estimate the position of the motor rotor and calculate the rotor electrical angle θ e The motor speed is estimated, compared with the motor speed, and closed-loop control is performed to achieve precise motor regulation. When the tension direct drive mechanism is in low-speed motion, it uses a speed sensorless vector control algorithm to generate a linear traveling wave magnetic field on the motor rotor. This magnetic field interacts with the excitation flux of the motor's stator permanent magnets, generating direct tension and tightening the power cord. The DSP control chip performs coordinate transformation based on the two collected first inverter outputs to calculate an estimated rotor electrical angle. This estimated rotor electrical angle is then used to generate the first PWM control signal for feedback to the IPM inverter circuit.

[0058] When the tension sensor detects that the direct tension generated by the tension direct drive mechanism reaches the preset tension value, the DSP control chip switches to tension feedback closed-loop control with a fixed electromagnetic space vector; by detecting the module length of the voltage space vector output by the second inverter, the second PWM control signal acting on the IPM inverter circuit is adjusted and output.

[0059] The following is an introduction to the low-speed mobile operation mode of the detection process. The structural block diagram is as follows Figure 3 As shown in the figure, in low-speed operation mode, the entire system is divided into two control loops, namely the outer speed loop and the inner current loop. The speed loop and the current loop are used together to perform field-oriented space vector modulation, and the output first PWM control signal corresponds to the modulation output of SVPWM. The AC input of the IPM inverter circuit is V DC , the output driving voltage is V a 、V b and V c , which is the IPM drive signal, controls the PMSN (excitation synchronous motor).

[0060] Considering that the sampling period of the current loop is 10 times that of the speed outer loop, it is necessary to collect the two-phase current values ​​through the Hall current sensor and send them to the DSP control chip for calculation. Figure 4 , including the following steps:

[0061] Step 401: In the i-th cycle, the collected driving current i a and i b Perform fixed-point calculations and calculate the drive current i based on the phase relationship c .

[0062] This application is described in detail with any i-th cycle. The conditioned driving current i is obtained by the current detection and conditioning circuit. a and i b After that, the analog-to-digital conversion is performed through the ADC conversion module built into the DSP control chip, and then the fixed-point conversion is performed according to the specified fixed-point format. Since there is a definite relationship between the three-phase drive currents, the third-phase drive current i can be calculated according to the phase relationship. c , driving current i c For use in subsequent processes.

[0063] Step 402: Clark transformation is used to convert the three-phase inverter output drive current i a 、i b and i c Perform orthogonal coordinate transformation to convert the driving current from the as-bs-cs coordinate system to the intermediate driving current i in the α-β coordinate system sα and i sβ .

[0064] Clark transformation is to transform the three-dimensional spatial coordinate system into a rectangular coordinate system, that is, to orthogonalize the vector and transform any two-phase drive current from the as-bs-cs coordinate system into the intermediate drive current i in the α-β coordinate system. sα and i sβ , that is, the component of the driving current in the vertical direction.

[0065] Step 403: Obtain the estimated value of the rotor electrical angle in the i-1th cycle, and use Park transformation to transform the intermediate drive current i in the α-β coordinate system. sα and i sβ Perform the rotation coordinate transformation and convert it into the feedback current i in the dqn coordinate system sd and i sq .

[0066] The purpose of Park transformation is to convert the projection on the β-β coordinate system into the dqn coordinate system, that is, to convert the intermediate drive current i sα and i sβ Perform the rotation coordinate transformation, which is equivalent to the d-axis and q-axis, and convert the current on the stator to the direct axis and quadrature axis. After conversion, the output is the feedback current i sd and i sqIn this way, we no longer need to worry about the rotating magnetic field generated by the three stator windings, but only about the rotating magnetic fields generated by the equivalent direct and quadrature axes. It should be noted that the Park transform requires the estimated rotor electrical angle of the previous cycle. That is, the estimated rotor electrical angle is used to perform the Park transform and update the intermediate drive current of the current cycle i.

[0067] Step 404: Obtain the intermediate drive voltage V output by the speed loop and the current loop in the (i-1)th cycle respectively. sdref and V sqref , combined with the feedback drive current i in the i-th cycle sd and i sq , calculate and obtain the estimated value of the rotor electrical angle in the i-th cycle.

[0068] Since this solution uses sensorless measurement of the rotor electrical angle estimate, such as Figure 3 As shown, the input of the speed loop and current loop before Park inverse transformation is the intermediate drive voltage V sdref and V sqref The intermediate drive voltage is the voltage after PI adjustment. When measuring the angle, it is necessary to obtain the intermediate drive voltage V of the previous cycle (i-1 cycle) sdref and V sqref Then, combined with the feedback current i after Park transformation sd and i sq , perform rotor position estimation and determine the estimated rotor electrical angle value for the i-th cycle. The purpose of obtaining the estimated rotor electrical angle value is to determine the current rotor speed n, which is also an estimated value.

[0069] Step 405: Calculate the estimated speed n of the motor rotor based on the estimated value of the rotor electrical angle and the feedback drive current of the i-th cycle, and calculate the estimated speed n based on the estimated speed n and the real-time speed n. ref The difference is adjusted by PI to obtain the second reference current i of the speed loop sqref .

[0070] like Figure 3 As shown, the second reference current is the current determined by the speed loop according to the speed difference and the first-level PI adjustment. The second reference current and the Park transformation output feedback current i sq The difference between the two values ​​is adjusted by the second stage PI and the output is the intermediate driving voltage, that is, the intermediate driving voltage V of the i-th cycle is obtained. sqref Similarly, the first reference current i of the current loop is sdref is 0, which is used to perform closed-loop control on the d-axis current and output the feedback current i through Park transformation. sd The difference between the two values ​​is adjusted by PI and the output is the intermediate driving voltage, that is, the intermediate driving voltage V in the i-th cycle is obtained.sdref .

[0071] Step 406: Based on the intermediate driving voltage V sdref and V sqref As the inverse transformation input, the calculated rotor electrical angle estimate is combined with the Park inverse transformation to obtain the voltage space vector V of the i-th cycle. sαref and V sβref .

[0072] Park transform is used to project and rotate complex space vectors onto the dq axis for computational convenience. When performing vector modulation, Park inverse transform is also required. The inverse transform process needs to be combined with the rotor electrical angle estimate calculated in the i-th cycle to calculate the intermediate drive voltage V sdref and V sqref Inverse transformation, return to the α-β coordinate system, and obtain the voltage space vector V of the i-th period in this coordinate system sαref and V sβref .

[0073] Step 407: voltage space vector V sαref and V sβref Perform space vector pulse width modulation (SVPWM) calculation to obtain a first PWM control signal.

[0074] This step needs to be based on the voltage space vector V sαref and V sβref The direction and size of the pulse are modulated, and the SVPWM module inside the DSP control chip calculates and obtains the first PWM control signal composed of three PWM duty cycle values.

[0075] The DSP control chip also integrates an event manager, which is required to perform dead-zone adjustments on the first PWM control signal to prevent signal errors. The DSP control chip also has an external isolation drive circuit connected between the DSP control chip and the IPM inverter circuit. This circuit isolates the voltage of the output PWM control signal and drives the IPM inverter circuit output to act on the tension direct drive mechanism.

[0076] In the low-speed operation mode, the direct tension value detected by the tension sensor increases. When it reaches the preset tension value for the first time, the mode switching starts and the second PWM control signal output process is performed. At the same time, the voltage space vector when the constant tension operation mode is reached needs to be recorded. Its structural block diagram is as follows Figure 5 shown.

[0077] In the constant tension operation mode, the PID regulator is needed to control the size of the voltage space vector (module length), thereby automatically adjusting the size of the excitation current to achieve closed-loop precise control of the tension. The system adopts PID closed-loop control of direct tension, while effectively resisting the influence of displacement disturbance on tension. Figure 6 As shown, the following steps are included:

[0078] In step 601, the DSP control chip performs coordinate transformation based on the two collected first inverter outputs, calculates an estimated rotor electrical angle, and calculates a first PWM control signal fed back to the IPM inverter circuit based on the estimated rotor electrical angle.

[0079] Step 602: When the direct pulling force exerted by the tension direct drive mechanism on the power line reaches a preset pulling force value, the voltage space vector corresponding to the preset pulling force value is determined as a constant voltage space vector, and the corresponding rotor electrical angle estimation value is determined as a reference electrical angle.

[0080] In step 603, the direct tension detected by the tension sensor is used as the negative feedback input of the PID negative feedback control system, and the preset tension value is used as the system input. PID adjustment is performed based on the difference between the two, and the adjustment output is used as the modulus reference of the voltage space vector.

[0081] First, the tension sensor is used to detect and convert the measured direct tension value F through the ADC conversion module of the DSP control chip, which is used as the negative feedback of the closed-loop control. ref The deviation from the F value is PID-regulated, and the output voltage space vector modulus reference is That is, the two-phase voltage V output by the IPM inverter circuit a and V b (corresponding to i a and i b ) is the modulus of the space voltage vector formed by . At the same time, the estimated value of the rotor electrical angle when the low-speed moving mode reaches the preset pulling force value is determined as the reference electrical angle, and the voltage space vector V obtained in the corresponding period is sαref and V sβref Will serve as a constant input in constant tension operating mode.

[0082] Step 604 : Based on the reference electrical angle and the constant voltage space vector, SVPWM calculation is performed in combination with the size of the module length reference, and modulation is performed to obtain a second PWM control signal.

[0083] The ultimate goal of this step is to ensure that the modulus and modulus reference remain consistent, or the difference is maintained within the error range, by continuously adjusting the direction and magnitude of the space voltage, so as to output the corresponding second PWM control signal.sαref and V sβref This is the target adjustment data for maintaining constant tension. However, because changes in wire stress and deformation can cause changes in the measured spatial voltage vector or rotor electrical angle, this step requires real-time adjustment and change of the output voltage vector to maintain stability.

[0084] Finally, the three PWM duty cycle values ​​calculated by the SVPWM module are used to update the corresponding registers. The event manager then outputs the second PWM control signal after adjusting for deadband. Because this process must continue for a certain period of time according to national standards, the wires may deform and shift during this time, causing changes in the tension sensor data and representing a system disturbance. The SVPWM module dynamically adjusts the PWM output through PID control based on the module length and tension difference to maintain stable output from the tension direct drive mechanism.

[0085] In order to complete the analysis of tension data, the DSP control chip is also provided with a JTAG port, which is connected to the host computer through a JTAG emulator. The host computer performs data display and debugging, and analyzes the test data of the power cord.

[0086] In summary, this solution replaces the traditional mechanical power source with a direct-drive tension control mechanism. This eliminates the need to convert the motor's rotational motion into linear motion, thus eliminating the need for a mechanical power transmission mechanism. Therefore, the direct tension detected by the tension sensor represents the power generated by the motor rotor. Furthermore, this solution employs a sensorless rotor angle and speed estimation method, compensating for the response time difference between the current loop and the speed loop. In low-speed mobile operation, a two-stage closed-loop control system, comprised of a current loop and a speed loop, is employed. Through multiple coordinate transformations, the acquired two-phase drive currents are orthogonally projected and rotated, simplifying the calculation complexity of the rotor drive current in a three-dimensional coordinate system. This dual closed-loop control effectively improves the system's response speed and detection accuracy, enhancing its anti-interference capabilities. In constant-tension operation, PID closed-loop control is performed based on the rotor electrical angle estimate and spatial voltage vector at the preset tension value. This provides precise tension values ​​during rotor stall, eliminating tension overshoot caused by system hysteresis, preventing the generation of explosive force, and improving system stability.

[0087] The above describes the preferred embodiments of the present invention; it should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can make many possible changes and modifications without departing from the technical solution of the present invention, or modify them into equivalent embodiments with equivalent changes, which does not affect the essential content of the present invention; therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A tension direct drive control system for power line tension testing, characterized in that: The system includes a tension direct drive mechanism, a tension sensor, a DSP control chip and an IPM inverter circuit; wherein the DSP control chip and the IPM inverter circuit constitute a direct drive closed-loop control system to perform closed-loop control on the tension direct drive mechanism; The IPM inverter circuit is connected to a rectified and filtered power input, and is used to output a three-phase drive voltage after inversion to act on the tension direct drive mechanism; the tension direct drive mechanism is connected to the tension sensor, and is used to generate a linear tension directly acting on the power line; The DSP control chip is connected to the tension sensor and the two inverter outputs of the IPM inverter circuit, and is used to analyze the input tension value and the inverter output, determine the operating state of the tension direct drive mechanism, and output a PWM control signal acting on the IPM inverter based on the operating state; Wherein, before the direct pulling force exerted by the tension direct drive mechanism on the power line reaches a preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform a first inverter output, and the first inverter output is used to control the tension direct drive mechanism to enter a low-speed moving operation state; after the direct pulling force exerted by the tension direct drive mechanism on the power line reaches the preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform a second inverter output, and the second inverter output is used to control the tension direct drive mechanism to maintain a constant pulling force operation state; When the tension sensor detects that the direct tension generated by the tension direct drive mechanism reaches the preset tension value, the tension direct drive mechanism enters a blocked working state; the DSP control chip switches to tension feedback closed-loop control with a fixed electromagnetic space vector; and by detecting the module length of the voltage space vector output by the second inverter, adjusts and outputs a second PWM control signal acting on the IPM inverter circuit; When the direct pulling force exerted by the tension direct drive mechanism on the power line reaches the preset pulling force value, the voltage space vector corresponding to the preset pulling force value is determined as a constant voltage space vector, and the corresponding rotor electrical angle estimation value is determined as a reference electrical angle; The direct tension detected by the tension sensor is used as the negative feedback input of the proportional integral differential PID negative feedback control system, the preset tension value is used as the system input, PID adjustment is performed based on the difference between the two, and the adjustment output is used as the modulus reference of the voltage space vector Based on the reference electrical angle and the constant voltage space vector, SVPWM calculation is performed in combination with the size of the module length reference, and modulation is performed to obtain the second PWM control signal; the second PWM control signal includes 3 PWM duty cycles.

2. The control system according to claim 1, characterized in that: The tension direct drive mechanism is composed of a permanent magnet motor and is rigidly connected to the tension sensor. When the tension direct drive mechanism is in a low-speed moving operation state, it interacts with the excitation flux of the motor stator permanent magnet to generate direct tension and tighten the power cord. The DSP control chip performs coordinate transformation based on the collected two-way first inverter output to calculate the rotor electrical angle estimation value θ e , and calculates a first PWM control signal fed back to the IPM inverter circuit based on the rotor electrical angle estimation value.

3. The control system according to claim 2, characterized in that: The DSP control chip is also connected to a current detection and conditioning circuit and an isolation drive circuit; the current detection and conditioning circuit is connected to the two inverter outputs of the IPM inverter circuit and is used to condition and detect the driving current i of the two inverter outputs. a and i b The DSP control chip receives the driving current through the ADC module, and calculates and outputs the PWM control signal according to the direct tension detected by the tension sensor; The isolation drive circuit is connected between the DSP control chip and the IPM inverter circuit, and is used to perform voltage isolation on the output PWM control signal and drive the IPM inverter circuit.

4. The control system according to claim 3, characterized in that: The direct drive closed loop control includes a speed loop and a current loop. The reference speed input of the speed loop is the real-time speed n of the motor rotor. ref , the first reference current i of the current loop sdref is 0; The DSP control chip performs coordinate transformation based on the collected two-way first inverter output to calculate the rotor electrical angle estimation value θ e , and calculating a first PWM control signal fed back to the IPM inverter circuit based on the estimated value of the rotor electrical angle, including: In the i-th cycle, the collected driving current i a and i b Perform fixed-point calculations and calculate the drive current i based on the phase relationship c ; i is a positive integer greater than 0; Clark transformation is used to transform the driving current i of the three-phase inverter output a 、i b and i c Perform orthogonal coordinate transformation to convert the driving current from the as-bs-cs coordinate system to the intermediate driving current i in the α-β coordinate system sα and i sβ ; Obtain the estimated value of the rotor electrical angle in the i-1th cycle, and use Park transformation to transform the intermediate drive current i in the α-β coordinate system sα and i sβ Perform the rotation coordinate transformation and convert it into the feedback current i in the dqn coordinate system sd and i sq ; Among them, i sd Feedback to the speed loop, i sq Feedback to the current loop; Obtain the intermediate drive voltage V of the speed loop and current loop in the i-1th cycle proportional integral PI regulation output respectively sdref and V sqref , combined with the feedback current i in the i-th cycle sd and i sq , calculate and obtain the rotor electrical angle estimation value within the i-th cycle; wherein, the rotor electrical angle estimation value is used for Park transform and Park inverse transform calculation.

5. The control system according to claim 4, characterized in that: After the calculation obtains the estimated value of the rotor electrical angle in the i-th cycle: Based on the rotor electrical angle estimation value and the feedback current of the i-th cycle, the estimated speed n of the motor rotor is calculated, and based on the estimated speed n and the real-time speed n ref The difference is adjusted by PI to obtain the second reference current i of the speed loop. sqref The first reference current and the second reference current are respectively related to the intermediate drive current i sα and i sβ The difference is PI-adjusted, and the output is the intermediate drive voltage V in the dqn coordinate system. sdref and V sqref ; Based on the intermediate driving voltage V sdref and V sqref As the inverse transformation input, the calculated rotor electrical angle estimation value is combined to perform Park inverse transformation to obtain the voltage space vector V of the i-th cycle sαref and V sβref ; The voltage space vector V sαref and V sβref Perform space vector pulse width modulation (SVPWM) calculation to obtain the first PWM control signal; the first PWM control signal includes three PWM duty cycles.

6. The control system according to any one of claims 1 to 5, characterized in that: The DSP control chip has a built-in event manager, which is used to perform dead-zone adjustment on the modulated output PWM control signal to obtain a corresponding space vector PWM control signal.

7. The control system according to any one of claims 1 to 5, characterized in that: The DSP control chip is also provided with a JTAG port, which is connected to a host computer via a JTAG emulator, and program debugging and data burning are performed via the host computer.

8. The control system according to claim 4, characterized in that: The speed loop is the outer loop of the system, the current loop is the inner loop of the system, and the sampling period of the current loop is 10 times that of the speed loop; the current detection and conditioning circuit detects the two-phase drive current through a Hall current sensor.

9. A tension direct drive control device for power line tension test, characterized in that: The device includes a support frame, a power cord, a fixing bracket, a baffle, a fixing device, a tension sensor, a tension direct drive mechanism, a direct drive closed loop controller and a sliding clamping mechanism; The tension direct drive mechanism is horizontally fixed on the support frame and connected to the tension sensor via a rigid connecting rod; the tension sensor is located on the sliding clamping mechanism and is located in the same horizontal direction as the tension direct drive mechanism; The sliding clamping mechanism can drive the tension sensor to slide between the baffle and the tension direct drive mechanism; The fixing bracket is installed on the side of the support frame, and the fixing device is fixedly placed on the top. The baffle is provided between the fixing device and the tension sensor, and a wire threading hole is opened in the center. The power cord is fixed to the fixing device and the tension sensor through the wire threading hole; The tension direct drive mechanism is connected to the direct drive closed-loop controller, and the DSP control chip and the IPM inverter circuit inside the closed-loop controller constitute a direct drive closed-loop control system to perform closed-loop control on the tension direct drive mechanism; The IPM inverter circuit is connected to a rectified and filtered power input, and is used to output a three-phase drive voltage after inversion to act on the tension direct drive mechanism; the tension direct drive mechanism is connected to the tension sensor, and is used to generate a linear tension directly acting on the power line; The DSP control chip is connected to the tension sensor and the two inverter outputs of the IPM inverter circuit, and is used to analyze the input tension value and the inverter output, determine the operating state of the tension direct drive mechanism, and output a PWM control signal acting on the IPM inverter based on the operating state; Wherein, before the direct pulling force exerted by the tension direct drive mechanism on the power line reaches a preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform a first inverter output, and the first inverter output is used to control the tension direct drive mechanism to enter a low-speed moving operation state; after the direct pulling force exerted by the tension direct drive mechanism on the power line reaches the preset pulling force value, the PWM control signal controls the IPM inverter circuit to perform a second inverter output, and the second inverter output is used to control the tension direct drive mechanism to maintain a constant pulling force operation state; When the tension sensor detects that the direct tension generated by the tension direct drive mechanism reaches the preset tension value, the tension direct drive mechanism enters a blocked working state; the DSP control chip switches to tension feedback closed-loop control with a fixed electromagnetic space vector; and by detecting the module length of the voltage space vector output by the second inverter, adjusts and outputs a second PWM control signal acting on the IPM inverter circuit; When the direct pulling force exerted by the tension direct drive mechanism on the power line reaches the preset pulling force value, the voltage space vector corresponding to the preset pulling force value is determined as a constant voltage space vector, and the corresponding rotor electrical angle estimation value is determined as a reference electrical angle; The direct tension detected by the tension sensor is used as the negative feedback input of the proportional integral differential PID negative feedback control system, the preset tension value is used as the system input, PID adjustment is performed based on the difference between the two, and the adjustment output is used as the modulus reference of the voltage space vector Based on the reference electrical angle and the constant voltage space vector, SVPWM calculation is performed in combination with the size of the module length reference, and modulation is performed to obtain the second PWM control signal; the second PWM control signal includes 3 PWM duty cycles.

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