Method for indirectly measuring resistance or resistance moment of output end of series excitation direct current motor driving equipment

Abstract

The invention relates to the technical field of motor monitoring, and discloses a series excitation direct current motor driving equipment output end resistance or resistance torque indirect measurement method comprising the following steps: taking the series excitation direct current motor driving equipment output end resistance or resistance torque as a parameter to be measured; when the equipment driven by the series excitation direct current motor is at the calibrated working voltage, acquiring the rotating speed of the series excitation direct current motor when the to-be-measured parameter is zero and the maximum, and taking the rotating speed as a no-load rotating speed and an overload rotating speed; determining to-be-tested parameters corresponding to two preset rotating speeds selected between the no-load rotating speed and the overload rotating speed; in the rectangular plane coordinate system, sequentially connecting coordinate points formed by the no-load rotating speed and the corresponding to-be-measured parameters, coordinate points formed by the two preset rotating speeds and the corresponding to-be-measured parameters, and coordinate points formed by the overload rotating speed and the corresponding to-be-measured parameters to construct three line segments; and selecting a corresponding target line segment from the three line segments according to the target rotating speed of the series excitation direct current motor so as to realize parameter measurement through the linear relation indicated by the target line segment.

Description

Technical Field

[0001] This invention relates to the field of motor monitoring technology for DC motor driven equipment, and particularly to an indirect method for measuring the output resistance or resistance torque of a series-wound DC motor driven equipment. Background Technology

[0002] In engineering practice, there are many motor-driven devices with varying loads, such as devices driven by series-wound DC motors. To ensure the safe, reliable, and long-term operation of these devices, it is necessary to monitor the load in real time to prevent long-term overload operation and to perform timely maintenance and repairs based on the load conditions. Typically, the resistance or resistance torque at the output end of the device can be monitored for this purpose.

[0003] Monitoring the output of equipment typically involves installing corresponding sensors at the measurement point, such as torque sensors, tension / compression sensors, and shear force sensors. However, the output of equipment is usually a moving component. After installing the corresponding sensor, the wires will move with the component being measured. Furthermore, the measurement results of the resistance or torque at the output of the equipment do not include the resistance of the equipment's transmission parts, i.e., they do not include the internal resistance of the equipment. In other words, directly measuring the resistance or torque at the output of the equipment cannot measure changes in the internal resistance of the equipment, resulting in the inability to monitor internal deterioration conditions, such as increased internal resistance due to worsening internal friction. Summary of the Invention

[0004] The purpose of this invention is to provide an indirect method for measuring the output resistance or resistance torque of a series-wound DC motor drive device, which can solve the problems of sensor wires following the movement and the lack of measurement or sensing of changes in internal resistance of the device caused by direct measurement.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide an indirect method for measuring the output resistance or resistance torque of a series-wound DC motor drive device, comprising the following steps: The output resistance or resistance torque of the equipment driven by the series-wound DC motor is taken as the parameter to be measured. When the equipment driven by the series-wound DC motor is at the rated operating voltage, the speed of the series-wound DC motor when the parameter to be measured is zero and when it is at its maximum is obtained, which are used as the no-load speed and overload speed. The parameters to be measured are determined based on two preset speeds selected between no-load speed and overload speed, according to a preset method. In a Cartesian coordinate system, three line segments are constructed by sequentially connecting the coordinate points formed by the no-load speed and the corresponding measured parameter, the coordinate points formed by the two preset speeds and their respective measured parameters, and the coordinate points formed by the overload speed and the corresponding measured parameter. Obtain the target speed of the series-wound DC motor, and select the corresponding target line segment from three line segments according to the target speed, so as to determine the corresponding parameter to be measured through the linear relationship indicated by the target line segment, and obtain the resistance or resistance torque at the output end of the device driven by the series-wound DC motor.

[0006] Optionally, the determining the parameters to be measured corresponding to two preset speeds selected between the no-load speed and the overload speed according to a preset method includes: Substitute the no-load speed and the corresponding parameter to be measured, as well as the overload speed and the corresponding parameter to be measured into the formula F×n + c×n = d or (F + c)×n = d in sequence to calculate c and d; where F represents the parameter to be measured, and n represents the speed of the series-wound DC motor; Select two preset speeds n1 = (n_overload + n0) / 2 and n2 = n_overload + 0.25×(n1 - n_overload) between the no-load speed and the overload speed, and substitute the two preset speeds into the formula F×n + c×n = d or (F + c)×n = d respectively. After obtaining the corresponding F values by using the calculated c and d, multiply them by the corresponding preset coefficients to obtain the corresponding parameters to be measured.

[0007] Optionally, the preset coefficients k1 and k2 corresponding to the two preset speeds are respectively: 0.3 ≤ k1 ≤ 0.7, 0.5 ≤ k2 ≤ 0.9.

[0008] Optionally, the determining the corresponding parameter to be measured through the linear relationship indicated by the target line segment includes: Record the coordinate points formed by the no-load speed and the corresponding parameter to be measured, the two preset speeds and their corresponding parameters to be measured, and the overload speed and the corresponding parameter to be measured in the plane rectangular coordinate system as (n0, F0), (n1, F1), (n2, F2), and (n_overload, F_overload) in sequence, and record the target speed as n; When n1 ≤ n ≤ n0, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n0, F0) and (n1, F1); When n2 ≤ n < n1, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n1, F1) and (n2, F2); When n_overload ≤ n < n2, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n2, F2) and (n_overload, F_overload).

[0009] Optionally, after obtaining the target speed of the series-wound DC motor, it further includes: When n > n0, if (n-n0) / n0 > 0.1, then output a warning message: The speed of the series-wound DC motor is too high. Check if the equipment is being driven in reverse by resistance. Otherwise, output a warning message: Check if the speed sensor or voltage is normal. When n ≤ n overload, if (n overload - n) / n overload > 0.1, then output a warning message: The speed of the series-wound DC motor is too low. Check if the equipment resistance or resistance torque is too high or if the internal resistance of the equipment is too high. Otherwise, output a warning message: Check if the speed sensor or voltage is normal.

[0010] Optionally, if the power transmission path of the device driven by the series DC motor has a resistance limiting mechanism and a resistance torque limiting mechanism, then after obtaining the target speed of the series DC motor, the method further includes: When n≤n is overloaded, output a warning message: check if the set value of the resistance or torque limiting mechanism has increased.

[0011] Optionally, the resistance limiting mechanism and the resistance torque limiting mechanism are torque limiters or friction couplings.

[0012] Optionally, the device driven by the series-wound DC motor is a switch machine.

[0013] The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device provided by this invention has at least the following beneficial effects: Because the internal resistance of motor-driven equipment changes during operation, an increase in internal resistance has an effect equivalent to an increase in external resistance. If the external resistance at the equipment's output terminal is directly measured, the increase in internal resistance will not be reflected in the test data. This invention does not employ a direct measurement method but instead chooses an indirect (non-contact) measurement method. It utilizes the mathematical relationship between the resistance or torque at the output terminal of the equipment when it is operating at its calibrated voltage and the corresponding rotational speed to measure the resistance or torque at the equipment's output terminal. The internal resistance of the equipment is fixed during calibration. When the internal resistance changes relative to the calibration time, it will be reflected in the test data. In other words, the final test data (resistance or torque) obtained by this invention is the sum of the equipment's internal resistance and the resistance or torque at the equipment's output terminal, minus the equipment's internal resistance at the calibration time. Thus, by simultaneously measuring the changes in the equipment's output terminal resistance and torque, and the equipment's internal resistance, when a significant increase in resistance is detected, a temporary direct measurement of the external resistance can distinguish whether the increase is due to an increase in the equipment's output terminal resistance or torque, an increase in the equipment's internal resistance, or both. This provides direction for equipment maintenance and repair. Attached Figure Description

[0014] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0015] Figure 1 This is a flowchart of an indirect measurement method for the output resistance or resistance torque of a series-wound DC motor drive device according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the relationship between the output power and speed of a series-wound DC motor according to an embodiment of the present invention; Figure 3 This is a schematic diagram comparing measured data of rotational speed and resistance, and a curve fitted according to the reciprocal relationship after measuring two points, provided by an embodiment of the present invention. Figure 4 This is a schematic diagram comparing measured data of rotational speed and resistance provided according to an embodiment of the present invention with the three line segments constructed by the present invention; Figure 5 This is a schematic diagram comparing the calculation and construction of three-segment curves after measuring P0 and P overload according to an embodiment of the present invention, and the fitted curve according to the reciprocal relationship. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0017] For equipment with varying loads, both the output resistance and the internal resistance are external loads on the drive motor. Changes in these loads are reflected in changes in motor parameters, typically torque, current, and speed. Therefore, monitoring methods for measuring motor parameters may include changes in the resistance of the transmission components. Torque measurement under motor operating conditions is difficult to perform without affecting motor operation or direct measurement. Typically, motor torque or the resistance / resistance torque at the measured position can be indirectly reflected by measuring other parameters. To ensure equipment safety and reliability, non-contact measurement methods should be selected whenever possible.

[0018] For example, in railway turnout switch machine applications, when it is necessary to measure the resistance of the switch machine's actuating lever, this can be achieved by measuring the switch machine's motor parameters. Specifically, this involves non-contact measurement of the motor speed or other rotating parts in the transmission mechanism that have a proportional relationship with the motor speed. Based on the relationship between motor speed and torque under constant operating voltage, and the relationship between driving torque and output force during mechanical transmission, the speed and output force relationship is calibrated and measured at specified points under the working environment (operating voltage). Further calculations are performed according to a predetermined method to obtain the relationship curve between speed and output force under the current environment. Then, the speed is measured, and the corresponding output force is calculated using the obtained relationship curve, thus indirectly measuring the switching resistance of the switch machine's actuating lever.

[0019] The above method is applicable to mechanical transmission mechanisms that use a three-phase AC motor as a power source, but this idea can be extended to motors that operate under other types of power sources and the mechanical transmission mechanisms they drive.

[0020] For DC motors, under constant voltage, their operating current is usually proportional to their torque. Therefore, by measuring the current and torque or current and output force at two operating points under the operating power supply, the torque-current relationship curve or current-output force relationship curve under that power supply can be calculated according to the linear relationship. Then, by calculating the measured current according to this relationship curve, the corresponding torque or output force value can be obtained. The operating current of a DC motor can be measured using a Hall sensor in a non-contact manner. Therefore, by measuring the operating current and the corresponding torque or output force in a non-contact manner, the linear relationship curve can be obtained from the data of the two operating points for measurement and calculation.

[0021] However, due to various limitations, such as expensive sensors, mismatch between the measurement range and current value, or inability of the sensor to meet environmental temperature requirements, it is necessary to consider non-contact methods to measure other motor parameters to obtain torque or output force values. Currently, non-contact methods for real-time monitoring of motor speed are already used in engineering practice. Therefore, studying the relationship between motor speed and torque, and even the output power of its driving equipment, and applying it to engineering practice, is of practical significance.

[0022] Since there are mature, low-cost, and widely applicable non-contact measurement methods for measuring the rotation angle and speed of rotating parts, and since motor speed and torque are correlated under constant voltage, the corresponding torque can be calculated from the speed based on this relationship. Therefore, this invention solves the engineering application method of measuring the speed non-contactly and calculating the motor torque or the output force of the mechanical mechanism.

[0023] One embodiment of the present invention relates to an indirect method for measuring the output resistance or resistive torque of a series-wound DC motor drive device. The specific process of the indirect measurement method for the output resistance or resistive torque of the series-wound DC motor drive device in this embodiment can be as follows: Figure 1 As shown, it includes: Step 101: Using the output resistance or resistance torque of the device driven by the series-wound DC motor as the parameter to be measured, when the device driven by the series-wound DC motor is at the rated operating voltage, obtain the speed of the series-wound DC motor when the parameter to be measured is zero and when it is at its maximum, and use these as the no-load speed and overload speed.

[0024] Among them, the equipment driven by a series-wound DC motor can be a switch machine.

[0025] Step 102: Determine the parameters to be measured for two preset speeds selected between no-load speed and overload speed according to the preset method.

[0026] Specifically, the no-load speed and the corresponding measured parameter, as well as the overload speed and the corresponding measured parameter, are substituted into the formula F×n+c×n=d or (F+c)×n=d to calculate c and d; where F represents the measured parameter and n represents the speed of the series-wound DC motor. Two preset speeds are selected between the no-load speed and the overload speed: n1 = (noverload + n0) / 2 and n2 = noverload + 0.25 × (n1 - noverload). The two preset speeds are substituted into the formula F × n + c × n = d or (F + c) × n = d respectively. After calculating c and d, the corresponding F values ​​are obtained. Then, the corresponding preset coefficients are multiplied to obtain the corresponding parameters to be measured.

[0027] Among them, the preset coefficients k1 and k2 corresponding to the two preset speeds are 0.3≤k1≤0.7 and 0.5≤k2≤0.9, respectively.

[0028] Step 103: In the Cartesian coordinate system, connect the coordinate points formed by the no-load speed and the corresponding measured parameter, the coordinate points formed by the two preset speeds and their respective measured parameters, and the coordinate points formed by the overload speed and the corresponding measured parameter in sequence to construct three line segments.

[0029] Step 104: Obtain the target speed of the series-wound DC motor, and select the corresponding target line segment from the three line segments according to the target speed. Determine the corresponding test parameter through the linear relationship indicated by the target line segment, and obtain the resistance or resistance torque at the output end of the device driven by the series-wound DC motor.

[0030] Specifically, the coordinate points formed by the no-load speed and the corresponding parameter to be measured, two preset speeds and their respective corresponding parameters to be measured, and the overload speed and the corresponding parameter to be measured in the plane rectangular coordinate system are successively denoted as (n0, F0), (n1, F1), (n2, F2), and (n overload, F overload), and the target speed is denoted as n; When n1 ≤ n ≤ n0, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n0, F0) and (n1, F1); When n2 ≤ n < n1, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n1, F1) and (n2, F2); When n overload ≤ n < n2, determine the parameter to be measured corresponding to the target speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n2, F2) and (n overload, F overload).

[0031] In an example, after obtaining the target speed of the series-wound DC motor: When n > n0, if (n - n0) / n0 > 0.1, output a warning message: The speed of the series-wound DC motor is too high. Check if there is a situation where the device is driven in the reverse direction by resistance; otherwise, output a warning message: Check if the speed sensor or voltage is normal; When n ≤ n overload, if (n overload - n) / n overload > 0.1, output a warning message: The speed of the series-wound DC motor is too low. Check if the device resistance or resistance torque is too large or if the internal resistance of the device is too large; otherwise, output a warning message: Check if the speed sensor or voltage is normal.

[0032] In an example, if the power transmission path of the device driven by the series-wound DC motor has a resistance limiting mechanism and a resistance torque limiting mechanism, after obtaining the target speed of the series-wound DC motor, when n ≤ n overload, output a warning message: Check if the set value of the resistance or torque limiting mechanism has increased.

[0033] Among them, the resistance limiting mechanism and the resistance torque limiting mechanism are torque limiters or friction couplings.

[0034] Next, the implementation details of the non-contact measurement method for the output device resistance or resistance torque of the series-wound DC motor in this embodiment will be specifically described. The following content is only the implementation details provided for easy understanding and is not necessary for implementing this solution.

[0035] For a series-wound DC motor, as the load changes, its output power and speed both change. According to the analysis of the measured data under a certain voltage, it can be found that there is a linear relationship between the output power and the speed, as shown in Figure 2. Under a constant voltage, the motor speed is denoted as n, the motor torque is denoted as T, and the motor output power is denoted as P. The relationship among the motor output power, torque, and speed is T = 9550P / n. When the external resistance changes, the motor speed and output power will change accordingly. The relationship between its output power and speed is Figure 2 as shown, that is, P = kn + b. Where k and b are constants, it can be obtained that when the external resistance changes, the relationship between the motor speed and torque is T = 9550k + 9550b / n. Let c = 9550k and d = 9550b, then T = c + d / n.

[0036] When the motor drives a mechanical mechanism through mechanical transmission, it is considered that the efficiency and reduction ratio of the transmission link are constant. The efficiency from the motor to the output end is expressed as η, and the reduction ratio is denoted as i. If the output power at the output end is expressed as F×V (linear motion at the output end) or T_out×n_out / 9550 (rotational motion at the output end), then η×P = F×V, and V = ki×n, where ki represents the proportional relationship between the linear motion speed and speed at the output end; or η×P = T_out×n_out / 9550, and n_out = i×n.

[0037] Substitute η×P = F×V into T = 9550P / n, then F×V = η×T×n / 9550; That is, F×ki×n = η×T×n / 9550, and it can be obtained that F = η×T / (9550×ki), indicating that F is proportional to T. The relationship is denoted as F = k1×T = k1(c1 + d1 / n) = k1×c1 + k1×d1 / n.

[0038] Similarly, substitute η×P = T_out×n_out / 9550 into T = 9550P / n, and there is η×T×n = T_out×n_out, that is, η×T = T_out×i, indicating that T_out is proportional to T, and further denoted as T_out = k2×T = k2(c2 + d2 / n) = k2×c2 + k2×d2 / n.

[0039] It can be seen that whether it is the motor torque or the torque or output force (external resistance) output by the mechanical mechanism driven by the motor, the following relationship exists with the motor speed: T = c3 + d3 / n or F = c4 + d4 / n, where c3, c4 and d3, d4 are constants.

[0040] Therefore, for mechanical transmission mechanisms driven by series motors, parameters c3, d3 or c4, d4 can be calibrated under the applied voltage or in the operating environment. That is, in the field working environment, the motor torque or the torque of the component under test in the transmission link and its corresponding motor speed or transmission component speed, the external force on the component under test and its corresponding motor speed or transmission component speed are measured, and the constants c3, d3 or c4, d4 are solved. Then, under the condition that the field environment remains unchanged, the corresponding torque or external force value on the component can be calculated based on the calculated formula when the speed is measured.

[0041] The following explanations all use resistance measurement methods. Resistance torque can be referred to the resistance measurement method, and will not be repeated here.

[0042] When a transmission mechanism contains flexible parts or parts that undergo rigidity-flexibility changes beyond a critical value (such as friction couplings), the power transmission becomes nonlinear due to energy storage, release, and consumption. Therefore, the aforementioned formula is not entirely valid. Before slippage occurs, the friction coupling is equivalent to a rigid part, and the aforementioned formula and method can be used.

[0043] Taking a switch machine as an example, this paper studies its practical application. Switch machines require monitoring the resistance of their actuating rods. Direct measurement methods using force pins or strain gauges on the actuating rods pose safety risks and raise concerns about the long-term reliability of the measured parts due to difficulties in protecting the sensor wires. Indirectly obtaining the actuating rod resistance by monitoring other parameters can solve the reliability and safety requirements for long-term measurement. Furthermore, non-contact methods can be used for monitoring moving parts, and since the detection head is fixed, the protection of power and data wires is relatively simple.

[0044] DC switch machines are typically driven by series-wound DC motors. Therefore, before the friction coupling slips, their rotational speed and the output force of the actuating rod conform to the relationship F=c+d / n.

[0045] With zero resistance in the actuator rod, measure the gear speed (which is proportional to the gear meshing on the motor shaft). When the switch machine is in friction (the actuator rod is stuck and does not move), measure the actuator rod resistance and the gear speed at this time. Substitute these values ​​into the formula F=c+d / n to obtain c and d. Then, based on the calculated values ​​of c and d and the measured gear speed, calculate the corresponding actuator rod resistance using the formula F=c+d / n.

[0046] Because the distance between the switch machine and the power supply is relatively long, the resistance of the transmission line is usually not negligible. When the operating current changes, the voltage drop in the line is significant, causing the voltage drop at the motor terminals to change with the operating current. Since the speed of the series-wound motor also changes with the operating current, the speed and current of the switch machine are not constant during operation due to the non-constant resistance of the actuating rod, resulting in variations in the operating voltage at the motor terminals. Therefore, the aforementioned calculation formula needs to be modified to reflect the actual changes in the motor's operating voltage. Since the line resistance at the switch machine application site varies depending on the specific installation location and cable conditions, it is difficult to modify using a formula only related to speed. Using a fixed method or fixed value for modification to achieve the desired engineering application effect is feasible, simple, and practical.

[0047] Tests were conducted on a switch machine test bench to verify the measured values ​​of the actuating rod resistance and rotational speed. These values ​​were then compared with those calculated using the formula F=c+d / n. Figure 3 .

[0048] The dashed line in the figure is the curve of the calculated value, and the broken line segment is the line connecting the measured values. The maximum deviation between the calculated value and the measured value can reach 1kN. The unit of the vertical axis in the figure is 100N. The deviation gradually increases from the deviation from the calibration point, and after reaching a certain range, the deviation basically stabilizes at about 1kN.

[0049] To improve calculation accuracy, the fitted curve obtained from calibration was corrected by replacing the original reciprocal curve with several line segments. Two additional points were inserted between the two calibration points using technical means to construct a three-segment line curve for calculation. (See...) Figure 4 The solid broken line in the figure is the line connecting the measured values, while the dashed broken line is a three-segment broken line formed by constructing two points between the calibration points.

[0050] It can be seen that within the range of no-load speed to friction speed, the constructed line segment matches the measured value well, and the deviation is relatively small when used to calculate the output force of the switch machine's actuating rod by measuring the gear speed.

[0051] The specific method for constructing the insertion point is as follows: The direction of extension or retraction of the lever must be calibrated, and the steps are identical, following these steps: 1. Measure the gear speed when the resistance F0 of the switch machine's operating rod is zero, and record it as n0 and F0.

[0052] 2. Measure the resistance of the actuating rod and the gear speed when the switch machine is in a friction state (the actuating rod is stuck and the output force of the actuating rod is the maximum value under this setting state), and record them as n overload and F overload.

[0053] 3. Substitute the aforementioned measurement data into F*n+c*n=d or (F+c)*n=d respectively to calculate c and d.

[0054] 4. The sum of friction speed noverload and zero resistance speed n0 of the actuating rod, divided by 2, is the characteristic speed, denoted as n1 = (noverload + n0) / 2.

[0055] 5. Calculate the value corresponding to the rotational speed n1 of feature 1 according to F*n+c*n=d or (F+c)*n=d. 0.5 times the value is taken as the resistance of feature 1, and it is recorded as F1=0.5×(d / n1-c).

[0056] 6. The characteristic speed n1 minus the friction speed n overload by 0.25 times plus the friction speed n overload is the characteristic speed n2, denoted as n2 = n overload + (n1 - n overload) / 4.

[0057] 7. Calculate the value corresponding to the rotational speed n2 of characteristic 2 according to F*n+c*n=d or (F+c)*n=d. 0.7 times it is taken as the resistance of characteristic 2, and it is recorded as F2=0.7×(d / n2-c).

[0058] 8. Using gear speed as the x-axis and actuating rod resistance as the y-axis, construct the no-load point (n0, F0), characteristic point 1 (n1, F1), characteristic point 2 (n2, F2), and friction points (n overload, F overload), denoted as P0, P1, P2, and P overload respectively. Connect them sequentially to form three line segments, see... Figure 5 .

[0059] 9. Calculate the resistance F of the actuating rod based on the measured gear speed n. When n ≥ n0, F = 0, and when (n - n0) / n0 ≥ k3, i.e., exceeding the set no-load threshold, an alarm is triggered, indicating a possible turnout rebound. When n0 > n > n1, F is calculated according to the P0P1 line segment. When n1 > n > n2, F is calculated according to the P1P2 line segment. When n2 > n > n is overloaded, F is calculated according to the P2P overload line segment. When n ≤ n is overloaded, F ≥ F overload, and when (n-n) / n-n ≥ k4, i.e., exceeding the set friction threshold, an alarm is triggered, indicating that the friction of the switch machine has increased beyond the limit.

[0060] 10. The friction threshold k4 can be determined based on test data or empirical values, or based on the structural characteristics of the switch machine friction coupling, or based on the upper limit of the switch machine friction force, using F*n+c*n=d or (F+c)*n=d.

[0061] 11. The no-load threshold k3 can be determined based on test data or empirical values, or based on the acceptable limit of the rebound force. This limit is expressed as a value less than zero, representing the minimum value at which the turnout rebound force driving the action rod can be disregarded. It is calculated using F×n+c×n=d or (F+c)×n=d.

[0062] For other equipment, the interpolation method is used to calculate the resistance or force values ​​of selected parts in the transmission mechanism. The calculation method is the same as that for the switch machine, and the proportional values ​​in the interpolation calculation process are adjusted according to the actual situation. In summary:

[0063] The direction of force on each part must be individually calibrated, and the steps are the same, all following the steps below: 1. The gear (motor) speed when the measured part is not subjected to external force is denoted as n0 and F0.

[0064] 2. The gear (motor) speed when the tested part is under maximum stress is denoted as n overload and F overload.

[0065] 3. Substitute the aforementioned measurement data into F×n+c×n=d or (F+c)×n=d respectively to calculate c and d, and obtain the specific parameters of the reciprocal relationship.

[0066] 4. The sum of noverload and n0 divided by 2 is the characteristic speed, denoted as n1 = (noverload + n0) / 2.

[0067] 5. Calculate the resistance or force value of the part corresponding to the rotational speed n1 of characteristic 1 based on F×n+c×n=d or (F+c)×n=d. Take K1 times this resistance as the resistance of characteristic 1, denoted as F1=K1×(d / n1-c). K1 is not greater than 1, and is usually taken as 0.3. <K1<0.7。

[0068] 6. The characteristic speed n1 minus 0.25 times noverload plus noverload is the characteristic speed n2, denoted as n2 = noverload + (n1 - noverload) / 4.

[0069] 7. Calculate the actuating rod resistance corresponding to the rotational speed n2 of characteristic 2 using either F×n+c×n=d or (F+c)×n=d. Take K2 times this resistance as the characteristic 2 resistance, denoted as F2=K2×(d / n2-c). K2 is not greater than 1, and is usually taken as 0.5. <K1<0.9。

[0070] 8. Using the gear (motor) speed as the abscissa and the resistance or force value of the measured part as the ordinate, construct the no-load point, characteristic point 1, characteristic point 2, and overload point, respectively denoted as P0(n0, F0), P1(n1, F1), P2(n2, F2), and P overload (n overload, F overload). Connect them sequentially to form three line segments. See Figure 4

[0071] 9. Based on the measured gear (motor) speed n, calculate the resistance or force value F of the measured part. When n≥n0, F=0, and an alarm is triggered when n-n0 exceeds the set no-load threshold, indicating that the measured part may be driven in reverse. When n0>n>n1, F is calculated according to the P0P1 line segment. When n1>n>n2, F is calculated according to the P1P2 line segment. When n2>n>n is overloaded, F is calculated according to the P2P overload line segment. When n≤n is overloaded, F≥F is overloaded, and an alarm is triggered when n overloaded-n exceeds the set overload threshold, indicating that the resistance or force value of the measured part is too large and exceeds the limit.

[0072] 10. The overload threshold can be determined based on test data or empirical values, or it can be calculated using F×n+c×n=d or (F+c)×n=d based on the upper limit of the allowable overload.

[0073] 11. The no-load threshold can be determined based on test data or empirical values, or it can be calculated using F×n+c×n=d or (F+c)×n=d based on the acceptable limit for reverse drive. This limit is expressed as a value less than zero, indicating the maximum allowable speed when the equipment is reverse driven and the motor speed exceeds the no-load speed.

[0074] When the transmission mechanism of the equipment contains a maximum torque limiting mechanism or a maximum force limiting mechanism such as a torque limiter or friction coupling, the measured maximum torque or maximum force and the corresponding speed are used as the overload point data.

[0075] The indirect measurement method for output resistance or resistance torque of a series-wound DC motor drive device of the present invention has at least the following beneficial effects: 1. Rotational speed measurement can be performed using non-contact methods, and the torque or resistance value of the output end or intermediate components in the transmission structure can be calculated in real time through on-site calibration. Only the rotational speed and resistance values ​​under no-load and overload extreme conditions need to be measured. Through interpolation techniques, a line segment approximating the measured value can be obtained as a fitting curve for measurement calculations. Calibration and measurement workload is minimal and easy to perform on-site.

[0076] 2. Calculate the torque or resistance value of the output end or transmission intermediate parts through motor parameters. The premise is that the transmission efficiency from the motor output end to the calculation position is relatively constant at the calibration time. When the transmission efficiency decreases, it will be reflected at the calculation position. Therefore, it is helpful to detect the deterioration of the transmission link of the equipment. Especially when there is another direct measurement sensor at the calculation position, by comparison, it is possible to directly locate whether the transmission efficiency of the transmission link deteriorates or the resistance and resistance torque at the calculation position increases.

[0077] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the protection scope of this invention.

[0078] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the embodiments of the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of the present invention; therefore, the scope of protection of the embodiments of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device, characterized in that, The method includes: Taking the resistance or resistance torque at the output end of the device driven by the series-wound DC motor as the parameter to be measured. When the device driven by the series-wound DC motor is at the calibrated working voltage, obtain the rotational speeds of the series-wound DC motor when the parameter to be measured is zero and maximum, as the no-load rotational speed and the overload rotational speed; Determine the parameters to be measured corresponding to two preset rotational speeds selected between the no-load rotational speed and the overload rotational speed according to a preset method; In a plane rectangular coordinate system, sequentially connect the coordinate points formed by the no-load rotational speed and the corresponding parameter to be measured, the coordinate points formed by the two preset rotational speeds and their respective corresponding parameters to be measured, and the coordinate points formed by the overload rotational speed and the corresponding parameter to be measured to construct three line segments; Obtain the target rotational speed of the series-wound DC motor, and select the corresponding target line segment from the three line segments according to the target rotational speed, so as to determine the corresponding parameter to be measured through the linear relationship indicated by the target line segment, and obtain the resistance or resistance torque at the output end of the device driven by the series-wound DC motor.

2. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 1, characterized in that, The determining the parameters to be measured corresponding to two preset rotational speeds selected between the no-load rotational speed and the overload rotational speed according to a preset method includes: Substitute the no-load rotational speed and the corresponding parameter to be measured and the overload rotational speed and the corresponding parameter to be measured into the formula F×n + c×n = d or (F + c)×n = d in sequence to calculate c and d; where F represents the parameter to be measured and n represents the rotational speed of the series-wound DC motor; Select two preset rotational speeds n1 = (n_overload + n0) / 2 and n2 = n_overload + 0.25×(n1 - n_overload) between the no-load rotational speed and the overload rotational speed, and substitute the two preset rotational speeds into the formula F×n + c×n = d or (F + c)×n = d respectively. After using the calculated c and d to obtain the respective corresponding F values, multiply by the corresponding preset coefficients to obtain the respective corresponding parameters to be measured.

3. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 2, characterized in that, The preset coefficients k1 and k2 corresponding to the two preset rotational speeds are respectively: 0.3 ≤ k1 ≤ 0.7, 0.5 ≤ k2 ≤ 0.

9.

4. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 1, characterized in that, The determining the corresponding parameter to be measured through the linear relationship indicated by the target line segment includes: Sequentially record the coordinate points formed by the no-load rotational speed and the corresponding parameter to be measured, the two preset rotational speeds and their respective corresponding parameters to be measured, and the overload rotational speed and the corresponding parameter to be measured in the plane rectangular coordinate system as (n0, F0), (n1, F1), (n2, F2), and (n_overload, F_overload) respectively, and record the target rotational speed as n; When n1 ≤ n ≤ n0, determine the parameter to be measured corresponding to the target rotational speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n0, F0) and (n1, F1); When n2 ≤ n < n1, determine the parameter to be measured corresponding to the target rotational speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n1, F1) and (n2, F2); When n_overload ≤ n < n2, determine the parameter to be measured corresponding to the target rotational speed according to the linear relationship indicated by the line segment formed by connecting the two coordinate points (n2, F2) and (n_overload, F_overload).

5. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 4, characterized in that, After the obtaining the target rotational speed of the series-wound DC motor, it further includes: When n > n0, if (n-n0) / n0 > 0.1, then output a warning message: The speed of the series-wound DC motor is too high. Check if the equipment is being driven in reverse by resistance. Otherwise, output a warning message: Check if the speed sensor or voltage is normal. When n ≤ n overload, if (n overload - n) / n overload > 0.1, then output a warning message: The speed of the series-wound DC motor is too low. Check if the equipment resistance or resistance torque is too high or if the internal resistance of the equipment is too high. Otherwise, output a warning message: Check if the speed sensor or voltage is normal.

6. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 1, characterized in that, If the power transmission path of the device driven by the series DC motor has a resistance limiting mechanism or a resistance torque limiting mechanism, then after obtaining the target speed of the series DC motor, the following is also included: When n≤n is overloaded, output a warning message: check if the set value of the resistance or torque limiting mechanism has increased.

7. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 6, characterized in that, The resistance limiting mechanism or resistance torque limiting mechanism is a torque limiter or a friction coupling.

8. The method for indirectly measuring the output resistance or resistance torque of a series-wound DC motor drive device according to claim 1, characterized in that, The device driven by the series-wound DC motor is a switch machine.

Images