A high current servo driver current control method and system

Abstract

The present application relates to the field of motor control technology, and specifically to a current control method and system for a high-current servo driver, the method comprising: obtaining the actual speed of the servo motor at each moment in the current acquisition cycle and multiple previous historical acquisition cycles, and the target speed at each moment input into the servo driver by the PID controller; determining the speed deviation and speed difference at each moment in each historical cycle; determining the speed fluctuation in each historical cycle; determining the wave velocity change rate at each moment; determining the speed trend deviation at each moment in each historical cycle; determining the control threshold at each moment; and combining the PID control algorithm to obtain the output current of the servo driver at each moment in the current acquisition cycle. The present application can eliminate the frequent control of the servo motor due to the small fluctuations that occur when the subway screen door is closed normally, and reduce the number of times the PID algorithm controls the servo driver to over-regulate the large current.

Description

Technical Field

[0001] The present application relates to the field of motor control technology, and in particular to a current control method and system for a high-current servo drive. Background Art

[0002] The high-current servo drive has the advantages of high power density, fast response and high reliability in controlling the servo motor. As an important part of urban rail transportation, the high-current DC motor is the main actuator of the subway screen door. The high-current servo drive provides a large input current for the DC motor of the subway screen door, which can quickly change the motor speed and torque, thereby achieving precise and rapid control of the subway screen door.

[0003] Affected by the environment and manufacturing process, the load on the motor of the rotating device in the subway screen door is slightly different each time it is closed normally, and the friction of the screen door at different positions is different, resulting in different forces on the motor when the subway screen door is closed, causing short-term fluctuations in the motor speed. The traditional PID (proportional-integral-derivative control) control algorithm uses the difference between the target speed output by the controller and the actual speed as input to adjust the output current in real time. When there is a slight fluctuation when the subway screen door is closed normally, the output current of the high-current servo driver is adjusted more frequently, resulting in an increase in the number of over-adjustments of the output high current, causing the servo motor to overheat and reduce its service life. Summary of the invention

[0004] In order to solve the above technical problems, a current control method and system of a large current servo driver are provided to solve the existing problems.

[0005] The solution to the technical problem of the present application is to provide a high-current servo drive current control method and system, including the following steps:

[0006] In a first aspect, an embodiment of the present application provides a current control method for a large current servo driver, the method comprising the following steps:

[0007] During each subway screen door closing process, the actual speed of the servo motor at each moment in the current collection cycle and the previous multiple historical collection cycles, as well as the target speed at each moment input into the servo driver by the PID controller are obtained, and the actual speed at each moment in all historical collection cycles before the current collection cycle are recorded as the historical speed set of the current collection cycle;

[0008] Determine the speed deviation at each moment in each historical cycle of the historical speed set according to the local difference between the actual speed and the target speed at each moment in each historical cycle of the historical speed set; analyze the similarity of the local changes of the actual speed and the target speed at different moments in each historical cycle, and determine the speed difference at each moment in each historical cycle of the historical speed set in combination with the speed deviation;

[0009] According to the local change trend of the actual speed at different moments in each historical cycle of the historical speed set, combined with the speed difference, the speed fluctuation degree in each historical cycle of the historical speed set is determined; the difference of the actual speed at adjacent moments in each historical cycle is analyzed, and the speed fluctuation degree of all historical cycles corresponding to the same moment is combined to determine the wave speed change rate at each moment; based on the wave speed change rate, the speed trend deviation at each moment in each historical cycle of the historical speed set is determined;

[0010] Based on the speed difference and the speed fluctuation, all historical periods corresponding to the same moment are clustered; according to the speed fluctuation within the cluster corresponding to each moment, combined with the speed trend deviation, the control threshold at each moment is determined; the relationship between the speed trend deviation and the control threshold at each moment in the current acquisition cycle is analyzed, and combined with the PID control algorithm, the output current of the servo driver at each moment in the current acquisition cycle is obtained.

[0011] Preferably, the determining of the speed deviation at each moment in each historical cycle of the historical speed set includes:

[0012] The actual speed at each moment and the previous moments in each historical cycle of the historical speed set is used as the local actual speed vector at each moment;

[0013] The target speed at each moment and the previous moments is used as the local target speed vector at each moment;

[0014] The difference between each element in the local actual speed vector and the element at the same position in the local target speed vector is calculated, and the sum of the differences of all elements is used as the speed deviation at each moment in each historical cycle of the historical speed set.

[0015] Preferably, the step of determining the speed difference at each moment in each historical cycle of the historical speed set includes:

[0016] Calculating the similarity between the local actual speed vector and the local target speed vector at each moment in each historical cycle of the historical speed set;

[0017] The ratio of the rotation speed deviation to the similarity is used as the rotation speed difference at each moment in each historical cycle of the historical rotation speed set.

[0018] Preferably, the determining of the speed fluctuation within each historical period of the historical speed set includes:

[0019] Perform linear fitting on the local actual speed vector at each moment in each historical cycle of the historical speed set to obtain the slope of the fitting line;

[0020] The product of the absolute value of the slope at each moment and the speed difference at the corresponding moment is calculated, and the average of the product at all moments in each historical period of the historical speed set is taken as the speed fluctuation in each historical period of the historical speed set.

[0021] Preferably, the wave velocity change rate at each moment is determined by calculating: ,in, For the The rate of change of wave velocity at a moment, is the first The speed fluctuation of the historical cycle, is the maximum speed fluctuation of all historical cycles of the historical speed set, is the number of all historical cycles in the historical speed set, is the first In the historical period The differential speed is the average of the differential speeds at all moments in the local actual speed vector at a moment, and the differential speed is the difference between the actual speed at each moment in each historical cycle of the historical speed set and the actual speed at the previous moment.

[0022] Preferably, the speed trend deviation at each moment in each historical period of the historical speed set is the difference between the differential speed at each moment in each historical period of the historical speed set and the wave speed change rate at the same moment.

[0023] Preferably, clustering all historical periods corresponding to the same time includes:

[0024] The speed difference at each moment in each historical cycle of the historical speed set and the speed fluctuation of the corresponding historical cycle form a speed fluctuation vector at each moment in each historical cycle of the historical speed set;

[0025] Cluster analysis is performed on all speed fluctuation vectors at the same time in all historical periods of the historical speed set to obtain multiple clusters corresponding to each moment.

[0026] Preferably, the control threshold at each moment is determined by the following calculation formula: ,in, For the The control threshold at the moment, For the The moment corresponding to The mean value of the modulus of all speed fluctuation vectors of the clusters, For the The moment corresponding to The maximum speed trend deviation within a cluster, For the The number of all clusters corresponding to the moment, is the normalization function.

[0027] Preferably, the step of obtaining the output current of the servo driver at each moment in the current acquisition cycle includes:

[0028] If the speed trend deviation at each moment in the current acquisition cycle is greater than the control threshold at the corresponding moment, the speed trend deviation at each moment in the current acquisition cycle is used as the input of the PID control algorithm to obtain the output current of the servo driver at each moment in the current acquisition cycle; otherwise, the output current of the servo driver is not adjusted.

[0029] In the second aspect, an embodiment of the present application also provides a high-current servo driver current control system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned high-current servo driver current control methods when executing the computer program.

[0030] This application has at least the following beneficial effects:

[0031] The present application determines the speed deviation at each moment in each historical cycle of the historical speed set according to the local difference between the actual speed and the target speed at each moment in each historical cycle of the historical speed set; analyzes the local change similarity between the actual speed and the target speed at different moments in each historical cycle to determine the speed difference at each moment in each historical cycle of the historical speed set, which has the beneficial effect of taking into account the deviation degree and change similarity degree between the local actual speed and the target speed at each moment and the moment before, so as to accurately extract the short-term fluctuation information of the motor speed and improve the accuracy of the subsequent servo driver in current control of the servo motor; determines the speed fluctuation degree in each historical cycle of the historical speed set according to the local change trend of the actual speed at different moments in each historical cycle of the historical speed set, which has the beneficial effect of reflecting the change trend and fluctuation degree of the speed of the servo motor during each subway screen door closing process; analyzes the difference in the actual speed at adjacent moments in each historical cycle, and determines the wave speed change rate at each moment in combination with the speed fluctuation degree of all historical cycles corresponding to the same moment; determines the speed trend deviation at each moment in each historical cycle of the historical speed set, The beneficial effect lies in that the difference between the change trend of the actual rotation speed at each moment and the average trend of the rotation speed at the same moment in the entire historical period is taken into account, the reliability of the analysis of the average change trend of the motor rotation speed when the shield door is closed normally for multiple times is improved, and the probability that the subsequent servo driver adjusts the current of the servo motor due to normal fluctuation of the rotation speed is reduced; based on the rotation speed difference and the rotation speed fluctuation, all historical periods corresponding to the same moment are clustered; according to the rotation speed fluctuation in the cluster corresponding to each moment, the control threshold of each moment is determined; the relationship between the rotation speed trend deviation and the control threshold at each moment in the current acquisition period is analyzed, and the output current of the servo driver at each moment in the current acquisition period is obtained in combination with the PID control algorithm. The beneficial effect lies in that the rotation speed fluctuation degree of the corresponding cluster at the same moment is taken into account to reflect the stability of the servo driver when the motor rotation speed is controlled multiple times, the rotation speed of the servo motor is controlled by the output current of the servo driver, and the frequent control of the servo motor due to the small fluctuation when the subway shield door is closed normally is eliminated, thereby reducing the number of times that the PID algorithm controls the servo driver to excessively regulate the large current, avoiding overheating of the servo motor, and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] A current control method for a high-current servo driver of the present application is further described in detail below in conjunction with the accompanying drawings.

[0033] Figure 1 A flowchart of a current control method for a high current servo drive provided in an embodiment of the present application;

[0034] Figure 2A flowchart of the steps of a method for obtaining the speed difference at each moment in each historical cycle of a historical speed set provided in an embodiment of the present application;

[0035] Figure 3 and Figure 4 A schematic diagram of the speed control of a servo motor by the improved PID control algorithm before and after the embodiment of the present application;

[0036] Figure 5 and Figure 6 Schematic diagram of controlling the output current of a servo driver using the improved PID control algorithm provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the following is a further detailed description of a high current servo drive current control method and system proposed in the present application in combination with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0039] See also Figure 1 , which shows a flow chart of a method for controlling a current of a high-current servo drive according to an embodiment of the present application, the method comprising the following steps:

[0040] Step 1: During each subway screen door closing process, obtain the actual speed of the servo motor at each moment in the current collection cycle and multiple previous historical collection cycles, as well as the target speed at each moment input into the servo driver by the PID controller, and record the actual speed at each moment in all historical collection cycles before the current collection cycle as the historical speed set of the current collection cycle.

[0041] The operation of the servo driver is controlled by the controller. The controller is responsible for sending instructions to the servo driver. The servo driver adjusts the output current according to the instructions, thereby controlling the speed of the servo motor. In order to monitor the rotation position and speed of the servo motor in real time, the encoder in the servo motor is used for monitoring, where the encoder is a sensor. Therefore, during the closing process of the subway screen door, the encoder starts counting the pulse signal, and the actual speed of the servo motor at each moment during the closing process of the subway screen door is calculated through the pulse signal obtained in the encoder, and the target speed at each moment input into the servo driver by the PID controller is obtained;

[0042] When the same target speed is input to the servo driver, the subway platform screen door is closed normally N times, and the actual speed of the servo motor at each moment during the N platform screen door closing processes is obtained. Each platform screen door closing process is regarded as a historical cycle, and the actual speed at each moment in the N historical cycles is recorded as a historical speed set. Secondly, the target speed at each moment input into the servo driver by the controller is obtained, wherein the target speed is the speed that the controller hopes the servo motor to reach.

[0043] It should be noted that the method of obtaining pulse signals in the encoder of the servo motor to calculate the actual rotation speed of the servo motor at each moment is a well-known technology and will not be described in detail here.

[0044] Preferably, in this embodiment, the subway platform screen door is normally closed 1000 times. As other implementation modes, the implementer can set them according to the actual situation.

[0045] Furthermore, the actual rotation speed of the servo motor at each moment of the current acquisition cycle during the closing process of the current subway platform screen door is obtained.

[0046] It should be noted that, assuming that it takes 5 seconds for the subway platform screen door to close from the beginning to the end, the number of pulse signals at each moment and within 50us before it is counted to obtain the actual rotation speed, which is used as the actual rotation speed at each moment. Therefore, during each closing process of the platform screen door, the number of actual rotation speeds at all moments in different historical periods in the historical rotation speed set is consistent.

[0047] At this point, the actual speed of the servo motor at each moment in the current acquisition cycle and multiple previous historical acquisition cycles, as well as the target speed at each moment input into the servo driver by the PID controller are obtained.

[0048] Step 2: Determine the speed deviation at each moment in each historical cycle of the historical speed set based on the local difference between the actual speed and the target speed at each moment in each historical cycle of the historical speed set; analyze the similarity of the local changes of the actual speed and the target speed at different moments in each historical cycle, and determine the speed difference at each moment in each historical cycle of the historical speed set in combination with the speed deviation.

[0049] When the servo drive controls the subway screen door to close normally, the vibration of the subway screen door during the train operation and the impact of passengers on the door body will cause the motor load to change temporarily. At the same time, small foreign objects in the subway screen door guide rail will cause the screen door to be temporarily stuck or not smooth during the closing process, resulting in changes in the force on the motor, causing the servo drive to control the motor speed to fluctuate temporarily.

[0050] Based on the above analysis, the short-term difference between the actual speed and the target speed of the servo motor is analyzed to reflect the degree of short-term fluctuation of the motor speed, specifically:

[0051] The actual speed at each moment and the previous moments in each historical cycle of the historical speed set is used as the local actual speed vector at each moment;

[0052] The target speed at each moment and the previous moments is used as the local target speed vector at each moment;

[0053] Preferably, in this embodiment, the actual speed and target speed at each moment and the 9 moments before it are selected as other implementations, and the implementer can set them according to the actual situation. It should be noted that when the length of the local actual speed vector and the local target speed vector is less than 10, the linear interpolation method is used to fill it completely, wherein the linear interpolation method is a well-known technology and will not be repeated here. As other implementations, the implementer can use other methods of the prior art, such as mean filling, spline interpolation, etc., and this embodiment does not impose any special restrictions on this.

[0054] Calculating the similarity between the local actual speed vector and the local target speed vector;

[0055] Preferably, in this embodiment, the cosine similarity between the local actual speed vector and the local target speed vector is calculated, wherein the method for calculating the cosine similarity is a well-known technology and will not be repeated here. As other implementation methods, the implementer may adopt other methods of the prior art, such as the Pearson correlation coefficient, etc. This embodiment does not impose any special restrictions on this.

[0056] Calculate the difference between each element in the local actual speed vector and the element at the same position in the local target speed vector, and use the sum of the differences of all elements as the speed deviation at each moment in each historical cycle;

[0057] Preferably, in this embodiment, the square of the difference between each element in the local actual speed vector and the element at the same position in the local target speed vector is calculated; in another embodiment, the absolute value of the difference between each element in the local actual speed vector and the element at the same position in the local target speed vector is calculated.

[0058] The ratio of the rotation speed deviation to the similarity is used as the rotation speed difference at each moment in each historical cycle of the historical rotation speed set;

[0059] Preferably, in this embodiment, the speed difference at each moment in each historical cycle of the historical speed set is calculated by the formula: ,in, is the first In the historical period The speed difference at each moment, is the first In the historical period The local actual speed vector at the moment elements, For the The local target speed vector at the moment elements, is the first In the historical period The local actual speed vector at the moment, For the The local target speed vector at the moment, is the number of all elements in the local target speed vector, To preset a value greater than 0 to avoid the denominator being 0, in this embodiment The value is 1. represents the calculation of similarity. In this embodiment, the cosine similarity is calculated. Secondly, is the speed deviation.

[0060] It should be noted that when the load of the servo motor changes briefly due to the change in the force of closing the subway screen door, the actual speed of the motor will change instantaneously, and there will be a slight difference between the target speed. Therefore, the smaller the similarity, the greater the difference between the actual speed of the motor and the target speed, the greater the speed deviation, and the greater the resulting speed difference, which means that the short-term difference between the actual speed of the motor controlled by the servo drive and the target speed is greater, that is, there is a short-term fluctuation.

[0061] Furthermore, the flowchart of the steps of the method for obtaining the speed difference at each moment in each historical cycle of the historical speed set provided by the embodiment of the present application is as follows: Figure 2 shown.

[0062] At this point, the speed difference at each moment in each historical cycle of the historical speed set is obtained.

[0063] Step 3: Determine the speed fluctuation within each historical period of the historical speed set based on the local change trend of the actual speed at different moments within each historical period of the historical speed set and the speed difference; analyze the difference in actual speed at adjacent moments within each historical period and determine the wave speed change rate at each moment based on the speed fluctuation of all historical periods corresponding to the same moment; determine the speed trend deviation at each moment within each historical period of the historical speed set based on the wave speed change rate.

[0064] Furthermore, in the process from the beginning of closing to the end of closing of the subway screen door, due to the change of inertia and load, the load on the servo motor will increase, and the motor speed will be easily affected and fluctuate during this process. Therefore, the change of speed at different stages when the subway screen door is closed is analyzed to reflect the overall fluctuation of the servo drive's control of the motor speed, specifically:

[0065] Perform linear fitting on the local actual speed vector at each moment in each historical cycle of the historical speed set to obtain the slope of the fitting line;

[0066] Preferably, in this embodiment, the least squares method is used for linear fitting, wherein the least squares method is a well-known technology and will not be described in detail here. As other implementation methods, the implementer can adopt other methods of the prior art, such as the maximum likelihood estimation method, and this embodiment does not impose any special restrictions on this.

[0067] Calculate the product of the absolute value of the slope at each moment and the speed difference at the corresponding moment, and take the average of the product at all moments in each historical period of the historical speed set as the speed fluctuation of each historical period of the historical speed set;

[0068] Preferably, in this embodiment, the calculation formula for the speed fluctuation of each historical period of the historical speed set is: ,in, is the first The speed fluctuation of the historical cycle, is the first In the historical period The speed difference at each moment, The historical speed set In the historical period The absolute value of the slope at the moment, is the first The number of all moments in the historical period.

[0069] It should be noted that the greater the speed difference, the greater the difference between the actual speed and the target speed of the servo motor; secondly, the greater the absolute value of the slope, the greater the rate of change of the servo motor speed in a short time, and the greater the probability of the subway screen door starting and stopping at the corresponding moment, and the greater the resulting speed fluctuation, which means that the overall fluctuation of the motor speed is more significant.

[0070] Furthermore, due to the existence of nonlinear links such as backlash in the mechanical transmission device of the subway screen door, the load on the servo motor generated by the subway screen door each time it is closed is different, and the change in the lubrication state of the screen door transmission system also affects the stability of the servo drive controlling the motor speed, resulting in different fluctuations in the motor speed. Therefore, at the same time in all historical cycles, the servo drive controls the motor speed. There are also differences. Therefore, the changes in the actual speed at the same time in all historical cycles are analyzed to determine the wave speed change rate at each moment, which is specifically:

[0071] The difference between the actual speed at each moment in each historical cycle of the historical speed set and the actual speed at the previous moment is taken as the differential speed at each moment;

[0072] Preferably, in this embodiment, the absolute value of the difference between the actual speed at each moment in each historical cycle of the historical speed set and the actual speed at the previous moment is taken as the differential speed at each moment.

[0073] The wave velocity change rate at each moment is calculated as: ,in, For the The rate of change of wave velocity at a moment, is the first The speed fluctuation of the historical cycle, is the maximum speed fluctuation of all historical cycles of the historical speed set, is the first In the historical period The average value of the differential speed at all times within the local actual speed vector at a time, is the number of all historical cycles of the historical speed set, that is, the data collected when the subway platform screen door is closed normally N times. In this embodiment, The value is 1000.

[0074] It should be noted that the mean, i.e. , can reduce the impact of slight speed fluctuations on the average speed change rate, and improve the accuracy of the subsequent servo driver in judging whether the motor speed needs current regulation. The servo driver controls the motor speed change rate to be small, and the differential speed in a short time is small. Secondly, when the subway screen door is closed, the greater the overall fluctuation, the greater the speed fluctuation, and the greater the obtained wave speed change rate, which means that when the servo driver controls the motor to rotate normally N times, in the first The greater the average rate of change of the motor speed at each moment, the greater the weight is given to the differential speed with a higher degree of overall speed fluctuation, which improves the reliability of the analysis of the average change trend of the motor speed when the shield door is closed normally for multiple times, and reduces the probability that the subsequent servo driver will adjust the current of the servo motor due to normal speed fluctuations.

[0075] Further, based on the wave speed change rate, the rotation speed trend deviation is determined to reflect the degree of difference in the trend change of the rotation speed at each moment, specifically:

[0076] The difference between the differential speed at each moment in each historical cycle of the historical speed set and the wave speed change rate at the same moment is used as the speed trend deviation at each moment in each historical cycle of the historical speed set;

[0077] Preferably, in this embodiment, the absolute value of the difference between the differential speed at each moment in each historical period of the historical speed set and the wave speed change rate at the same moment is used as the speed trend deviation at each moment in each historical period of the historical speed set.

[0078] It should be noted that the rotation speed trend deviation reflects the difference between the change trend at the corresponding moment and the average change trend of the rotation speed.

[0079] At this point, the speed trend deviation at each moment in each historical cycle of the historical speed set is obtained.

[0080] Step 4: Cluster all historical periods corresponding to the same moment based on the speed difference and the speed fluctuation; determine the control threshold at each moment according to the speed fluctuation in the cluster corresponding to each moment, combined with the speed trend deviation; analyze the relationship between the speed trend deviation and the control threshold at each moment in the current acquisition cycle, and obtain the output current of the servo driver at each moment in the current acquisition cycle in combination with the PID control algorithm.

[0081] Furthermore, considering that during the closing process of the subway platform screen door, the speed change deviation of the motor speed under different short-term fluctuations and overall fluctuations is quite different, therefore, based on the speed difference and the speed fluctuation, the control threshold is determined, specifically:

[0082] The speed difference at each moment in each historical cycle of the historical speed set and the speed fluctuation of the corresponding historical cycle form a speed fluctuation vector at each moment in each historical cycle of the historical speed set;

[0083] Using cluster analysis algorithm, cluster analysis is performed on all speed fluctuation vectors at the same moment in all historical cycles to obtain multiple clusters corresponding to each moment;

[0084] Preferably, in this embodiment, a fuzzy C-means clustering algorithm is used for clustering analysis, and the number of clusters is set to 5. As other implementation methods, the implementer can set it according to the actual situation. Among them, the fuzzy C-means clustering algorithm is a well-known technology and will not be repeated here. The implementer can adopt other methods of the existing technology, such as the DBSCAN clustering algorithm, etc. This embodiment does not impose any special restrictions on this.

[0085] The calculation formula of the control threshold at each moment is: ,in, For the The control threshold at the moment, For the The moment corresponding to The mean value of the modulus of all speed fluctuation vectors of the clusters, For the The moment corresponding to The maximum speed trend deviation within a cluster, For the The number of all clusters corresponding to the moment, is the normalization function.

[0086] It should be noted that The larger it is, the more unstable the servo drive's control over the motor speed is at the corresponding moment, and the greater the motor speed fluctuation when the subway screen door is closed normally. Therefore, a larger weight is given to the speed trend deviation to determine the control threshold.

[0087] Further, based on the control threshold, the current output in the servo driver is controlled, thereby controlling the speed of the servo motor, specifically:

[0088] Based on the actual speed at each moment in the current acquisition cycle, the speed trend deviation at each moment in the current acquisition cycle is calculated;

[0089] If the speed trend deviation at each moment in the current acquisition cycle is greater than the control threshold at the corresponding moment, the speed trend deviation at each moment in the current acquisition cycle is used as the input of the PID (proportional-integral-derivative control) control algorithm to obtain the output current of the servo driver at each moment and control the speed of the servo motor; if the speed trend deviation at each moment in the current acquisition cycle is less than or equal to the control threshold at the corresponding moment, the output current of the servo driver is not adjusted;

[0090] It should be noted that the parameters of the PID control algorithm are adjusted by a critical proportion method to obtain the output current. The PID control algorithm is a well-known technology and will not be described in detail here.

[0091] Further, the schematic diagram of the speed control of the servo motor by the improved PID control algorithm provided in this embodiment is as follows: Figure 3 and Figure 4 , where the horizontal axis is time and the vertical axis is the speed of the servo motor. Figure 5 and Figure 6 This is a schematic diagram of the output current of the servo driver controlled by the PID control algorithm before and after the improvement, where the horizontal axis is time and the vertical axis is the current output by the servo driver. Figure 3 and Figure 5 The speed and output current controlled by the traditional PID control algorithm are Figure 4 and Figure 6 The speed and output current controlled by the improved PID control algorithm are compared. Figure 3 , Figure 4 The speed fluctuation of the internal servo motor is relatively more stable. Secondly, compared with Figure 5 , Figure 6 The output current fluctuation is small, which reduces the number of times the servo motor's current is adjusted and controlled, making the servo motor's speed relatively stable.

[0092] Therefore, the speed of the servo motor is controlled by the output current of the servo driver, eliminating the frequent control of the servo motor due to the small fluctuations that occur when the subway screen door is closed normally, thereby reducing the number of times the PID control algorithm controls the servo driver to over-regulate the large current, avoiding overheating of the servo motor and extending its service life.

[0093] Based on the same inventive concept as the above method, an embodiment of the present application also provides a high-current servo driver current control system, including a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the steps of any one of the above-mentioned high-current servo driver current control methods are implemented.

[0094] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0095] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the present application. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solution of the present application, shall fall within the protection scope of the technical solution of the present application.

Claims

1. A current control method for a high current servo drive, characterized in that: The method comprises the following steps: During each subway screen door closing process, the actual speed of the servo motor at each moment in the current collection cycle and the previous multiple historical collection cycles, as well as the target speed at each moment input into the servo driver by the PID controller are obtained, and the actual speed at each moment in all historical collection cycles before the current collection cycle are recorded as the historical speed set of the current collection cycle; Determine the speed deviation at each moment in each historical cycle of the historical speed set according to the local difference between the actual speed and the target speed at each moment in each historical cycle of the historical speed set; analyze the similarity of the local changes of the actual speed and the target speed at different moments in each historical cycle, and determine the speed difference at each moment in each historical cycle of the historical speed set in combination with the speed deviation; According to the local change trend of the actual speed at different moments in each historical cycle of the historical speed set, combined with the speed difference, the speed fluctuation degree in each historical cycle of the historical speed set is determined; the difference of the actual speed at adjacent moments in each historical cycle is analyzed, and the speed fluctuation degree of all historical cycles corresponding to the same moment is combined to determine the wave speed change rate at each moment; based on the wave speed change rate, the speed trend deviation at each moment in each historical cycle of the historical speed set is determined; Based on the speed difference and the speed fluctuation, all historical periods corresponding to the same moment are clustered; according to the speed fluctuation in the cluster corresponding to each moment, combined with the speed trend deviation, the control threshold at each moment is determined; if the speed trend deviation at each moment in the current acquisition cycle is greater than the control threshold at the corresponding moment, the speed trend deviation at each moment in the current acquisition cycle is used as the input of the PID control algorithm to obtain the output current of the servo driver at each moment in the current acquisition cycle; otherwise, the output current of the servo driver is not adjusted; The control threshold at each moment is determined by the following calculation formula: ,in, For the The control threshold at the moment, For the The moment corresponding to The mean value of the modulus of all speed fluctuation vectors of the clusters, For the The moment corresponding to The maximum speed trend deviation within a cluster, For the The number of all clusters corresponding to the moment, is the normalization function.

2. A high current servo driver current control method as claimed in claim 1, characterized in that: The step of determining the speed deviation at each moment in each historical cycle of the historical speed set includes: The actual speed at each moment and the previous moments in each historical cycle of the historical speed set is used as the local actual speed vector at each moment; The target speed at each moment and the previous moments is used as the local target speed vector at each moment; The difference between each element in the local actual speed vector and the element at the same position in the local target speed vector is calculated, and the sum of the differences of all elements is used as the speed deviation at each moment in each historical cycle of the historical speed set.

3. A high current servo driver current control method as claimed in claim 2, characterized in that: The step of determining the speed difference at each moment in each historical cycle of the historical speed set includes: Calculating the similarity between the local actual speed vector and the local target speed vector at each moment in each historical cycle of the historical speed set; The ratio of the rotation speed deviation to the similarity is used as the rotation speed difference at each moment in each historical cycle of the historical rotation speed set.

4. A high current servo driver current control method as claimed in claim 2, characterized in that: The step of determining the speed fluctuation within each historical period of the historical speed set includes: Perform linear fitting on the local actual speed vector at each moment in each historical cycle of the historical speed set to obtain the slope of the fitting line; The product of the absolute value of the slope at each moment and the speed difference at the corresponding moment is calculated, and the average of the product at all moments in each historical period of the historical speed set is taken as the speed fluctuation in each historical period of the historical speed set.

5. A high current servo driver current control method as claimed in claim 2, characterized in that: The wave velocity change rate at each moment is determined by: ,in, For the The rate of change of wave velocity at a moment, is the first The speed fluctuation of the historical cycle, is the maximum speed fluctuation of all historical cycles of the historical speed set, is the number of all historical cycles in the historical speed set, is the first In the historical period The differential speed is the difference between the actual speed at each moment and the actual speed at the previous moment in each historical cycle of the historical speed set.

6. A high current servo driver current control method as claimed in claim 5, characterized in that: The speed trend deviation at each moment in each historical period of the historical speed set is the difference between the differential speed at each moment in each historical period of the historical speed set and the wave speed change rate at the same moment.

7. A high current servo driver current control method as claimed in claim 1, characterized in that: The clustering of all historical periods corresponding to the same moment includes: The speed difference at each moment in each historical cycle of the historical speed set and the speed fluctuation of the corresponding historical cycle form a speed fluctuation vector at each moment in each historical cycle of the historical speed set; Cluster analysis is performed on all speed fluctuation vectors at the same time in all historical periods of the historical speed set to obtain multiple clusters corresponding to each moment.

8. A high current servo drive current control system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of a high-current servo drive current control method as described in any one of claims 1-7 are implemented.

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