Control method, device and system of coal mining machine traction system

Abstract

The present disclosure relates to a control method, device and system of a coal mining machine traction system, belonging to the field of coal mining machines. The method is applied to a controller in the coal mining machine traction system. The method comprises: detecting the voltage value of a DC bus in real time; in response to the voltage value being lower than a first preset threshold, obtaining voltage fluctuation information within a preset time period; determining the predicted duration of DC bus under-voltage according to the voltage fluctuation information, and comparing it with a first target duration; in the case where the predicted duration is determined to be less than the first target duration, controlling the output frequency of the frequency converter according to the voltage fluctuation information to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to generate power at a reduced speed and feeding the generated power of the traction motor back to the DC bus through the inverter module to maintain the voltage of the DC bus. The robustness of the coal mining machine traction system under under-voltage conditions is ensured, and the reliable production of the coal mining machine traction system is guaranteed.

Description

Technical Field

[0001] This disclosure relates to the field of coal mining machines, and in particular to a control method, device and system for a coal mining machine traction system. Background Technology

[0002] Currently, during coal cutting operations, power supply fluctuations caused by long-distance underground power supply and the start-up of high-power loads can lead to undervoltage on the DC bus of the coal mining machine's traction inverter. In this situation, to protect the traction inverter and traction motor, the coal mining machine's traction system will be forced to shut down. Since the traction system is the source of power for the coal mining machine's movement, its shutdown will halt production at the entire working face, resulting in a loss of coal output. To resume production, the traction system of the coal mining machine usually needs to be reset, which also causes inconvenience to the production workers. Summary of the Invention

[0003] To overcome the problems existing in related technologies, this disclosure provides a control method, device and system for a coal mining machine traction system.

[0004] According to a first aspect of the present disclosure, a control method for a coal mining machine traction system is provided. The method is applied to a controller within the coal mining machine traction system. The system includes a frequency converter, a traction motor, and the controller. The frequency converter receives three-phase alternating current supplied by a transformer and rectifies the three-phase alternating current via a rectifier module, then inputs it to an inverter module via a DC bus to control the operation of the traction motor. The method includes:

[0005] Real-time monitoring of the voltage value of the DC bus;

[0006] In response to the voltage value being lower than a first preset threshold, voltage fluctuation information within a preset time period is acquired;

[0007] The predicted duration of the DC bus undervoltage is determined based on the voltage fluctuation information and compared with the first target duration.

[0008] If the predicted duration is determined to be less than the first target duration, the output frequency of the inverter is controlled according to the voltage fluctuation information to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce its speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage.

[0009] Optionally, the method includes:

[0010] Based on historical undervoltage data, generate multiple historical fluctuation vectors and store them locally;

[0011] The step of determining the predicted duration of the DC bus undervoltage based on the voltage fluctuation information includes:

[0012] Based on the voltage fluctuation information, a voltage fluctuation vector is generated;

[0013] Calculate the similarity distance between the voltage fluctuation vector and the plurality of historical fluctuation vectors;

[0014] The historical fluctuation vector that is closest to the voltage fluctuation vector is determined based on the similarity distance;

[0015] Based on the historical undervoltage data, the historical duration corresponding to the historical fluctuation vector is determined, and the predicted duration is obtained.

[0016] Optionally, the method includes:

[0017] The first target duration is determined based on the current voltage value and the current speed of the traction motor.

[0018] Optionally, the first target duration is determined based on the current voltage value and the current speed of the traction motor, including:

[0019] Determine the initial difference speed based on the current voltage value and the target voltage value;

[0020] Based on the initial difference speed and the current speed, the time required to adjust the traction motor to zero is determined, thus obtaining the first target time.

[0021] Optionally, the method includes:

[0022] If it is determined that the speed of the traction motor will be adjusted to less than or equal to zero in the next adjustment cycle of the PID regulation, and / or the voltage value is lower than the second preset threshold, a DC bus voltage low fault information is sent, and the voltage fluctuation information within the preset time period is stored as historical undervoltage data.

[0023] Optionally, the coal mining machine traction system further includes a supplementary power generation device, which is connected to the controller and the rectifier module of the frequency converter. The method includes:

[0024] If it is determined that the predicted duration is longer than the second target duration and / or the voltage value is lower than the second preset threshold, the inverter is controlled to stop working. The second target duration is determined based on the first target duration and the power generation capacity of the supplementary power generation device.

[0025] If it is determined that the predicted duration is greater than the first target duration and less than the second target duration, the supplementary power generation device is controlled to start.

[0026] In response to the next adjustment cycle of the PID control, the speed of the traction motor will be adjusted to be less than or equal to a preset speed threshold, and the output frequency of the inverter will be controlled to maintain the speed of the traction motor at the preset speed threshold; and,

[0027] Based on the voltage fluctuation information, the supplementary power generation device is controlled to output three-phase AC power to the rectifier module, so that the power generated by the supplementary power generation device is supplemented to the DC bus through the rectifier module to maintain the DC bus voltage.

[0028] Optionally, the method includes:

[0029] In response to the DC bus undervoltage recovery, the output frequency of the inverter is increased to the preset frequency before the DC bus undervoltage.

[0030] Optionally, the frequency converter includes a frequency converter slave and a frequency converter master, and the traction motor includes a first motor connected to the frequency converter master and a second motor connected to the frequency converter slave;

[0031] The step of controlling the output frequency of the frequency converter based on the voltage fluctuation information includes:

[0032] The output frequency of the inverter master is controlled according to the voltage fluctuation information, so that the inverter slave changes in response to the change of the output frequency of the inverter slave.

[0033] According to a second aspect of the present disclosure, a control device for a coal mining machine traction system is provided. The control device is applied to a controller in the coal mining machine traction system. The system includes a frequency converter, a traction motor, and the controller. The frequency converter is used to receive three-phase AC power supplied by a transformer, and rectifies the three-phase AC power through a rectifier module and inputs it to an inverter module through a DC bus to control the operation of the traction motor.

[0034] The control device includes:

[0035] The detection module is used to detect the voltage value of the DC bus in real time;

[0036] The acquisition module is used to acquire voltage fluctuation information within a preset time period in response to the voltage value being lower than a first preset threshold.

[0037] The prediction module is used to determine the predicted duration of the DC bus undervoltage based on the voltage fluctuation information and compare it with the first target duration.

[0038] The control module is used to control the output frequency of the inverter according to the voltage fluctuation information when it is determined that the predicted duration is less than the first target duration, so as to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce its speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage.

[0039] According to a third aspect of the present disclosure, a coal mining machine traction system is provided. The system includes a frequency converter, a traction motor, and a controller. The frequency converter is used to receive three-phase AC power supplied by a transformer, and rectifies the three-phase AC power through a rectifier module and inputs it to an inverter module through a DC bus to control the operation of the traction motor. The controller is used to execute the method described in any of the first aspects of the present disclosure.

[0040] The technical solutions provided by the embodiments of this disclosure can include the following beneficial effects: by real-time monitoring of the DC bus voltage value, and obtaining voltage fluctuation information for a certain period of time when the DC bus is determined to be undervoltage, and predicting the duration of undervoltage of the coal mining machine traction system based on the voltage fluctuation information, and when the predicted duration meets the preset threshold condition, controlling the output power of the frequency converter according to the voltage fluctuation information to achieve proportional-integral-derivative regulation of the traction motor speed, it can not only accurately predict the undervoltage duration, but also reliably control the speed of the traction motor through PID regulation to ensure the stability of the DC bus voltage, ensuring the robustness of the coal mining machine traction system under undervoltage conditions, and ensuring the reliable production of the coal mining machine traction system.

[0041] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0042] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0043] Figure 1 This is a flowchart illustrating a control method for a coal mining machine traction system according to an exemplary embodiment.

[0044] Figure 2 This is a block diagram illustrating a control device for a coal mining machine traction system according to an exemplary embodiment.

[0045] Figure 3 This is a block diagram illustrating a controller according to an exemplary embodiment.

[0046] Figure 4This is a schematic diagram of a coal mining machine traction system according to an exemplary embodiment. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0048] Currently, the walking power source of chainless electric traction coal mining machines is mainly provided by traction motors. In order to achieve controllable walking speed of the coal mining machine, and thus controllable coal cutting speed, frequency converters are usually used to control the traction motors using the principle of variable frequency speed regulation.

[0049] Currently, during coal cutting operations, power supply fluctuations caused by long-distance underground power supply and the start-up of high-power loads can lead to undervoltage on the DC bus of the coal mining machine's traction inverter. In this situation, to protect the traction inverter and traction motor, the coal mining machine's traction system will be forced to shut down. Since the traction system is the source of power for the coal mining machine's movement, its shutdown will halt production at the entire working face, resulting in a loss of coal output. To resume production, the traction system of the coal mining machine usually needs to be reset, which also causes inconvenience to the production workers.

[0050] Figure 1 This is a flowchart illustrating a control method for a coal mining machine traction system according to an exemplary embodiment. The method is applied to a controller in the coal mining machine traction system. The system includes a frequency converter, a traction motor, and the controller. The frequency converter receives three-phase AC power from a transformer, rectifies the three-phase AC power through a rectifier module, and then inputs it to an inverter module via a DC bus to control the operation of the traction motor. Figure 1 As shown, the method includes:

[0051] S101. Real-time detection of the voltage value of the DC bus.

[0052] The voltage value of the DC bus can be collected according to a preset period. The duration of the preset period can be a short duration, such as 1ms, 5ms or 10ms. This disclosure does not limit this.

[0053] S102. In response to the voltage value being lower than a first preset threshold, obtain voltage fluctuation information within a preset time period.

[0054] The first preset threshold may refer to the highest voltage value that may affect the operation of the coal mining machine traction system. That is, if the voltage is lower than the first preset threshold, the coal mining machine traction system may experience the risk that the power output of the frequency converter cannot meet the operation of the traction motor, thus causing the traction motor to shut down due to undervoltage.

[0055] Furthermore, the preset duration can be, for example, the voltage fluctuation information of the most recent 10 seconds or the most recent minute, and this disclosure does not limit the specific value of the preset duration. The scale of the voltage fluctuation information can be, for example, millivolts or 1 / 10 volt, and relevant personnel can set it according to their specific control accuracy or requirements, and this disclosure does not specifically limit it in this regard either.

[0056] S103. Determine the predicted duration of the DC bus undervoltage based on the voltage fluctuation information, and compare it with the first target duration.

[0057] The predicted duration of DC bus undervoltage can be obtained based on historical undervoltage data. It's understandable that in coal mining scenarios, power grid fluctuations are periodic. For example, high-power equipment in coal mines is typically turned on periodically, and the underground coal mining process proceeds relatively smoothly. Therefore, in this coal mining scenario, the duration of undervoltage in the coal mining machine's traction system can be predicted relatively accurately based on historical data.

[0058] In some possible implementations, the first target duration may be a preset duration. In other possible implementations, the first target duration may be determined based on the current DC bus voltage and the traction motor speed, which will be further described below and will not be repeated here.

[0059] S104. When it is determined that the predicted duration is less than the first target duration, the output frequency of the inverter is controlled according to the voltage fluctuation information to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce its speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage.

[0060] PID (Proportional-Integral-Derivative) regulation can be implemented through a PID controller within the controller. The inputs to this PID controller can include the historical speed, current speed, and target speed of the traction motor; alternatively, they can include the historical output frequency and target output frequency of the frequency converter. The output can be the control value of the frequency converter's output frequency. The target speed can be determined based on voltage fluctuation information, for example, based on the magnitude of voltage drop. The target output frequency can be determined based on the target speed. It is understood that the traction motor speed is positively correlated with the frequency converter's output frequency; that is, the higher the frequency converter's output frequency, the higher the traction motor speed. Furthermore, given the output and input parameters, the PID regulation parameters, such as proportional and integral parameters, can be calibrated based on actual needs. The specific control methods of PID regulation are well-known in the art and will not be elaborated further.

[0061] It is worth noting that when the output frequency of the inverter changes, causing the slip of the traction motor to become negative, the traction motor, which is an induction motor, can be put into a generator operation state, generating electrical power. The electrical energy generated by this traction motor is three-phase AC, which can then be inverted by the inverter module and fed back to the DC bus, thereby achieving low-voltage ride-through control that ensures the coal mining machine traction system can withstand DC bus undervoltage conditions.

[0062] In this embodiment, by real-time monitoring of the DC bus voltage value and obtaining voltage fluctuation information for a certain period of time when DC bus undervoltage is determined, the duration of undervoltage of the coal mining machine traction system is predicted based on the voltage fluctuation information. When the predicted duration meets a preset threshold condition, the output power of the frequency converter is controlled according to the voltage fluctuation information to achieve proportional-integral-derivative (PID) regulation of the traction motor speed. This not only accurately predicts the undervoltage duration but also reliably controls the traction motor speed through PID regulation to ensure the stability of the DC bus voltage, ensuring the robustness of the coal mining machine traction system under undervoltage conditions and guaranteeing reliable production of the coal mining machine traction system.

[0063] In some alternative embodiments, the method includes:

[0064] Based on historical undervoltage data, generate multiple historical fluctuation vectors and store them locally;

[0065] The step of predicting the duration of DC bus undervoltage based on the voltage fluctuation information includes: generating a voltage fluctuation vector based on the voltage fluctuation information; calculating the similarity distance between the voltage fluctuation vector and the plurality of historical fluctuation vectors; determining the historical fluctuation vector closest to the voltage fluctuation vector based on the similarity distance; and determining the historical duration corresponding to the historical fluctuation vector based on the historical undervoltage data to obtain the predicted duration.

[0066] Among them, the historical undervoltage data can be a collection of voltage fluctuation information collected in the history of the coal mining machine traction system or other coal mining machine traction systems after they are connected to the current power grid or other power grids. Each voltage fluctuation information can correspond to the duration of the historical record. The controller can generate a corresponding historical fluctuation vector based on each voltage fluctuation information in the historical undervoltage data.

[0067] Furthermore, the similarity distance between the voltage fluctuation vector and multiple historical fluctuation vectors can be calculated by Euclidean distance, Manhattan distance, or Mahalanobis distance between the voltage fluctuation vector and each historical fluctuation vector. This disclosure does not limit this, and those skilled in the art can configure it based on their actual needs.

[0068] In one possible implementation, a feature extraction model for extracting features of voltage fluctuation information can be pre-trained, and the historical undervoltage data and voltage fluctuation information can be input into the feature extraction model to obtain the aforementioned historical fluctuation vector and voltage fluctuation vector.

[0069] In another possible implementation, the voltage value acquired in each acquisition cycle can be used as an element in a vector space according to the time sequence, thereby obtaining the historical fluctuation vector of the corresponding historical undervoltage data and the voltage fluctuation vector of the corresponding voltage fluctuation information.

[0070] By adopting the above scheme, historical undervoltage data and its corresponding duration are collected, and multiple historical fluctuation vectors are generated based on the historical undervoltage data. Then, the similarity distance between the voltage fluctuation vector corresponding to the current voltage fluctuation information and each historical fluctuation vector is calculated, that is, the historical duration closest to the current power grid situation is obtained, which can accurately predict the duration of DC bus undervoltage under the current situation.

[0071] In some alternative embodiments, the method includes determining the first target duration based on the current voltage value and the current rotational speed of the traction motor.

[0072] The first target duration can be used to characterize the duration during which the current voltage value of the DC bus is kept above a first preset threshold and the traction motor can maintain a negative slip rate.

[0073] For example, the lower the current voltage value and the higher the current speed of the traction motor, the longer the first target duration can be. When the current voltage value is constant, the first target duration can be positively correlated with the speed of the traction motor; correspondingly, when the speed of the traction motor is constant, the first target duration can be negatively correlated with the current voltage value.

[0074] By adopting the above scheme, the first target duration for comparison with the predicted duration is determined based on the current voltage value and the current speed of the traction motor. This makes the first target duration more accurate, thereby ensuring the reliability of the frequency converter control, ensuring the robustness of the coal mining machine traction system under undervoltage conditions, and ensuring the reliable production of the coal mining machine traction system.

[0075] In an optional embodiment, determining the first target duration based on the current voltage value and the current rotational speed of the traction motor includes:

[0076] Determine the initial difference speed based on the current voltage value and the target voltage value;

[0077] Based on the initial difference speed and the current speed, the time required to adjust the traction motor to zero is determined, thus obtaining the first target time.

[0078] The target voltage value can be the DC bus voltage value when the coal mining machine traction system can work normally, and the initial speed difference value can be the speed difference required for the traction motor to feed back the current DC bus voltage to the target voltage.

[0079] In one possible implementation, the first target duration can be the first duration corresponding to the current rotational speed decreasing to zero, based on the rotational speed difference.

[0080] It is understandable that as the power grid fluctuates, the voltage supplied to the DC bus may also fluctuate, and consequently, the voltage fed back by the traction motor will also fluctuate, resulting in a certain error in the first target duration obtained through this implementation method.

[0081] In another possible implementation, based on historical undervoltage data, the average duration corresponding to reducing the first rotational speed to zero can be statistically obtained, and a confidence parameter can be determined based on the current rotational speed and the first rotational speed. Then, based on the first duration and the confidence parameter, a second duration can be calculated as the first target duration.

[0082] Those skilled in the art can select any of the above-described embodiments based on the controller configuration, such as computing power and power consumption limits, and this disclosure does not specifically limit them.

[0083] By adopting the above scheme, the initial difference speed is determined based on the current voltage value and the target voltage value, and the time required to adjust the traction motor to zero is determined based on the initial speed difference and the current speed of the traction motor. This further ensures the accuracy of the first target time, thereby ensuring the reliability of the frequency converter control, ensuring the robustness of the coal mining machine traction system under undervoltage conditions, and ensuring the reliable production of the coal mining machine traction system.

[0084] In some alternative embodiments, the method includes:

[0085] If it is determined that the speed of the traction motor will be adjusted to less than or equal to zero in the next adjustment cycle of the PID regulation, and / or the voltage value is lower than the second preset threshold, a DC bus voltage low fault information is sent, and the voltage fluctuation information within the preset time period is stored as historical undervoltage data.

[0086] The controller can also stop the inverter from working when it determines that the speed of the traction motor will be adjusted to less than or equal to zero in the next adjustment cycle of the PID adjustment, and / or the voltage value is lower than a second preset threshold.

[0087] In addition, the controller can send a control signal to the frequency converter in each adjustment cycle to control the output frequency of the frequency converter, thereby realizing PID regulation of the traction motor speed. When the speed of the traction motor is adjusted to less than or equal to zero, the traction motor may reverse and cause damage.

[0088] Furthermore, the DC bus voltage low fault information can include voltage fluctuation information, or it can be a preset prompt message. This fault information can be sent via email or SMS, or a control signal can be sent to a buzzer to make the buzzer sound an alarm to alert the staff. The controller can be configured with a memory to store this historical undervoltage data, or it can send this historical undervoltage data to a server so that other coal mining machine traction systems can obtain the historical undervoltage data and then control it.

[0089] In one possible implementation, the second preset threshold can be a pre-configured voltage value. When the voltage value of the DC bus is lower than the second preset threshold, it can be indicated that the coal mining machine traction system may not be working properly. That is, the second preset threshold can be equal to the minimum voltage value required to maintain the normal operation of the coal mining machine traction system.

[0090] In another possible implementation, the second preset threshold can be determined based on the speed difference corresponding to reliable power generation of the traction motor and the minimum voltage required for normal operation of the coal mining machine traction system. Specifically, the second preset threshold can be equal to the difference between the minimum voltage required for normal operation of the coal mining machine traction system and the power generation voltage corresponding to the speed difference corresponding to reliable power generation. That is, the second preset threshold can be the minimum voltage value that maintains the normal operation of the coal mining machine traction system under the condition of traction motor feedback voltage.

[0091] By adopting the above scheme, when it is determined that the output frequency of the frequency converter cannot be controlled to reduce the speed of the traction motor to feed back electrical energy, thus preventing the coal mining machine traction system from achieving low-voltage ride-through control, a DC bus voltage low fault information is sent, and the voltage fluctuation information within the preset time period is stored as historical undervoltage data. This not only allows the staff to adjust the coal mining machine traction system more promptly, but also allows for updating of historical data, thereby making subsequent control of the coal mining machine traction system more reliable and further ensuring the reliable production of the coal mining machine traction system.

[0092] In some alternative embodiments, the coal mining machine traction system further includes a supplementary power generation device connected to the controller and the rectifier module of the frequency converter, the method comprising:

[0093] If it is determined that the predicted duration is longer than the second target duration and / or the voltage value is lower than the second preset threshold, the inverter is controlled to stop working. The second target duration is determined based on the first target duration and the power generation capacity of the supplementary power generation device.

[0094] If it is determined that the predicted duration is greater than the first target duration and less than the second target duration, the supplementary power generation device is controlled to start.

[0095] In response to the next adjustment cycle of the PID control, the speed of the traction motor will be adjusted to be less than or equal to a preset speed threshold, and the output frequency of the inverter will be controlled to maintain the speed of the traction motor at the preset speed threshold; and,

[0096] Based on the voltage fluctuation information, the supplementary power generation device is controlled to output three-phase AC power to the rectifier module, so that the power generated by the supplementary power generation device is supplemented to the DC bus through the rectifier module to maintain the DC bus voltage.

[0097] The supplementary power generation device can start in advance without outputting to the frequency converter. Only when it is determined that the speed of the traction motor can no longer be reduced and the DC bus voltage provided by the power grid cannot support the normal operation of the coal mining machine traction system, will the controller control it to output to the frequency converter.

[0098] In one possible implementation, the supplementary power generation device can be a fuel-fired generator that can convert chemical energy into mechanical energy, thereby enabling the rotor to rotate in the stator and converting the mechanical energy into three-phase alternating current.

[0099] In another possible implementation, the supplementary power generation device may include a DC battery, a battery management system, and an inverter. After the supplementary power generation device is activated, the battery management system can detect the DC battery, and if the detection is normal, in response to the controller's control, connect the DC power supply to the inverter's contactor, thereby enabling the inverter to operate. Additionally, the coal mining machine traction system can also provide extra power to charge the supplementary power generation device, provided that the power supplied by the grid is sufficient for the traction motor's operation.

[0100] By adopting the above scheme, when the speed of the traction motor can no longer be reduced and the DC bus voltage provided by the power grid cannot support the normal operation of the coal mining machine traction system, the supplementary power generation device is used to generate supplementary power, thereby maintaining the voltage value of the inverter DC bus for a longer period of time. This ensures the robustness of the coal mining machine traction system under undervoltage conditions and guarantees the reliable production of the coal mining machine traction system.

[0101] In some embodiments, the method includes:

[0102] In response to the DC bus undervoltage recovery, the output frequency of the inverter is increased to the preset frequency before the DC bus undervoltage.

[0103] By adopting the above scheme, when the DC bus undervoltage recovery is confirmed, the output power of the frequency converter is controlled to recover in a timely manner. This enables the frequency converter to accelerate the motor again when the grid voltage is restored, returning it to the state before the grid fluctuation, thereby ensuring the reliable production of the coal mining machine traction system.

[0104] Optionally, the frequency converter includes a frequency converter slave and a frequency converter master, and the traction motor includes a first motor connected to the frequency converter master and a second motor connected to the frequency converter slave;

[0105] The step of controlling the output frequency of the frequency converter based on the voltage fluctuation information includes:

[0106] The output frequency of the inverter master is controlled according to the voltage fluctuation information, so that the inverter slave changes in response to the change of the output frequency of the inverter slave.

[0107] By adopting the above scheme, a one-to-one dual-motor coal mining machine traction system can be realized by setting up a frequency converter master and a frequency converter slave. The frequency converter slave can also be synchronized with the changes in the working mode of the frequency converter master. This can effectively improve the production efficiency of the coal mining machine traction system at a lower cost.

[0108] Based on the same inventive concept Figure 2 This is a schematic diagram of a control device for a coal mining machine traction system according to an exemplary embodiment, such as... Figure 2 As shown, the control device 20 of the coal mining machine traction system is used as the controller in the coal mining machine traction system. That is, the control device 20 of the coal mining machine traction system can be used as the controller in the coal mining traction system. The system includes a frequency converter, a traction motor, and the controller. The frequency converter is used to receive three-phase AC power from the transformer, and after rectifying the three-phase AC power through the rectifier module, it is input to the inverter module through the DC bus to control the operation of the traction motor. The control device 20 of the coal mining machine traction system includes:

[0109] Detection module 21 is used to detect the voltage value of the DC bus in real time;

[0110] The acquisition module 22 is used to acquire voltage fluctuation information within a preset time period in response to the voltage value being lower than a first preset threshold.

[0111] Prediction module 23 is used to determine the predicted duration of the DC bus undervoltage based on the voltage fluctuation information and compare it with the first target duration;

[0112] The control module 24 is used to control the output frequency of the inverter according to the voltage fluctuation information when it is determined that the predicted duration is less than the first target duration, so as to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce its speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage.

[0113] Optionally, the control device 20 of the coal mining machine traction system includes:

[0114] The generation module is used to generate multiple historical fluctuation vectors based on historical undervoltage data and store them locally;

[0115] The prediction module 23 is used for:

[0116] Based on the voltage fluctuation information, a voltage fluctuation vector is generated;

[0117] Calculate the similarity distance between the voltage fluctuation vector and the plurality of historical fluctuation vectors;

[0118] Based on the similarity distance, determine the historical fluctuation vector that is closest to the voltage fluctuation vector;

[0119] Based on the historical undervoltage data, the historical duration corresponding to the historical fluctuation vector is determined, and the predicted duration is obtained.

[0120] Optionally, the control device 20 of the coal mining machine traction system includes:

[0121] The determining module is used to determine the first target duration based on the current voltage value and the current speed of the traction motor.

[0122] Optionally, a module is defined for:

[0123] Determine the initial difference speed based on the current voltage value and the target voltage value;

[0124] Based on the initial difference speed and the current speed, the time required to adjust the traction motor to zero is determined, thus obtaining the first target time.

[0125] Optionally, the control device 20 of the coal mining machine traction system includes:

[0126] The prompting module is used to send DC bus voltage low fault information when it is determined that the speed of the traction motor will be adjusted to less than or equal to zero in the next adjustment cycle of the PID adjustment, and / or the voltage value is lower than a second preset threshold, and to store the voltage fluctuation information within the preset time period as historical undervoltage data.

[0127] Optionally, the coal mining machine traction system further includes a supplementary power generation device, which is connected to the controller and the rectifier module of the frequency converter. The control device 20 of the coal mining machine traction system includes:

[0128] The first control module is used to control the inverter to stop working when it is determined that the predicted duration is greater than the second target duration and / or the voltage value is lower than the second preset threshold. The second target duration is determined based on the first target duration and the power generation capacity of the supplementary power generation device.

[0129] The second control module is used to control the supplementary power generation device to start when it is determined that the predicted duration is greater than the first target duration and less than the second target duration.

[0130] The third control module is configured to, in response to the next adjustment cycle of the PID control, adjust the speed of the traction motor to be less than or equal to a preset speed threshold, control the output frequency of the inverter to maintain the speed of the traction motor at the preset speed threshold; and,

[0131] The fourth control module is used to control the supplementary power generation device to output three-phase AC power to the rectifier module according to the voltage fluctuation information, so that the power generated by the supplementary power generation device can be supplemented to the DC bus through the rectifier module to maintain the DC bus voltage.

[0132] Optionally, the control device 20 of the coal mining machine traction system includes:

[0133] In response to the DC bus undervoltage recovery, the output frequency of the inverter is increased to the preset frequency before the DC bus undervoltage.

[0134] Optionally, the frequency converter includes a frequency converter slave and a frequency converter master, and the traction motor includes a first motor connected to the frequency converter master and a second motor connected to the frequency converter slave;

[0135] The control module 24 is used to: control the output frequency of the inverter master according to the voltage fluctuation information, so that the inverter slave changes in response to the change of the output frequency of the inverter slave.

[0136] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0137] This disclosure also provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the steps of the control method for the coal mining machine traction system provided in this disclosure.

[0138] Figure 3 This is a block diagram illustrating a controller according to an exemplary embodiment. (Refer to...) Figure 3 The controller 300 may include one or more of the following components: processing component 302, memory 304, power supply component 306, multimedia component 308, audio component 310, input / output interface 312, sensor component 314, and communication component 316.

[0139] Processing component 302 typically controls the overall operation of controller 300, such as operations associated with display, telephone calls, data communication, camera operation, and recording. Processing component 302 may include one or more processors 320 to execute instructions to complete all or part of the steps of the methods described above. Furthermore, processing component 302 may include one or more modules to facilitate interaction between processing component 302 and other components. For example, processing component 302 may include a multimedia module to facilitate interaction between multimedia component 308 and processing component 302.

[0140] Memory 304 is configured to store various types of data to support operation on controller 300. Examples of this data include instructions for any application or method operating on controller 300, contact data, phonebook data, messages, pictures, videos, etc. Memory 304 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0141] Power supply component 306 provides power to various components of controller 300. Power supply component 306 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to controller 300.

[0142] The multimedia component 308 includes a screen that provides an output interface between the controller 300 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may sense not only the boundaries of the touch or swipe action but also the duration and pressure associated with the touch or swipe operation. In some embodiments, the multimedia component 308 includes a front-facing camera and / or a rear-facing camera. When the controller 300 is in an operating mode, such as a shooting mode or a video mode, the front-facing camera and / or the rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities.

[0143] Audio component 310 is configured to output and / or input audio signals. For example, audio component 310 includes a microphone (MIC) configured to receive external audio signals when controller 300 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 304 or transmitted via communication component 316. In some embodiments, audio component 310 also includes a speaker for outputting audio signals.

[0144] Input / output interface 312 provides an interface between processing component 302 and peripheral interface modules, which may be keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to, home buttons, volume buttons, start buttons, and lock buttons.

[0145] Sensor assembly 314 includes one or more sensors for providing status assessments of various aspects of controller 300. For example, sensor assembly 314 may detect the on / off state of controller 300, the relative positioning of components such as the display and keypad of controller 300, changes in the position of controller 300 or one of its components, the presence or absence of user contact with controller 300, the orientation or acceleration / deceleration of controller 300, and temperature changes of controller 300. Sensor assembly 314 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 314 may also include an optical sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, sensor assembly 314 may also include an accelerometer, gyroscope, magnetometer, pressure sensor, or temperature sensor.

[0146] Communication component 316 is configured to facilitate wired or wireless communication between controller 300 and other devices. Controller 300 can access wireless networks based on communication standards, such as WiFi, 2G, or 3G, or combinations thereof. In one exemplary embodiment, communication component 316 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 316 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0147] In an exemplary embodiment, the controller 300 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the methods described above.

[0148] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 304 including instructions, which can be executed by a processor 320 of a controller 300 to perform the above-described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0149] The aforementioned device can be a standalone electronic device or a part of a standalone electronic device. For example, in one embodiment, the device can be an integrated circuit (IC) or a chip, wherein the integrated circuit can be a single IC or a collection of multiple ICs. The chip can include, but is not limited to, the following types: GPU (Graphics Processing Unit), CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), and SoC (System on Chip). The aforementioned integrated circuit or chip can be used to execute executable instructions (or code) to implement the control method of the coal mining machine traction system described above. The executable instructions can be stored in the integrated circuit or chip or obtained from other devices or equipment. For example, the integrated circuit or chip includes a processor, memory, and an interface for communicating with other devices. The executable instructions can be stored in the memory, and when the executable instructions are executed by the processor, the control method of the coal mining machine traction system described above is implemented; or, the integrated circuit or chip can receive the executable instructions through the interface and transmit them to the processor for execution, so as to implement the control method of the coal mining machine traction system described above.

[0150] In another exemplary embodiment, a computer program product is also provided, comprising a computer program executable by a programmable device, the computer program having a code portion for performing the control method of the coal mining machine traction system described above when executed by the programmable device.

[0151] Figure 4 This is a schematic diagram illustrating a coal mining machine traction system according to an exemplary embodiment, such as... Figure 4 As shown, the coal mining machine traction system includes a frequency converter 410, a traction motor 420, and a controller 300. The frequency converter 410 receives three-phase AC power from the transformer 440, rectifies the three-phase AC power through a rectifier module 411, and then inputs it to the inverter module 412 via a DC bus to control the operation of the traction motor 420. The controller 300 is used to execute the steps described in the method of the above embodiment. The controller 300 can also be replaced with... Figure 2 The control device 20 of the coal mining machine traction system is shown.

[0152] Optionally, the coal mining machine traction system also includes a supplementary power generation device, which is connected to the controller and the rectifier module of the frequency converter.

[0153] Optionally, the frequency converter includes a slave frequency converter and a master frequency converter, and the traction motor includes a first motor connected to the master frequency converter and a second motor connected to the slave frequency converter. That is, the transformer 440 can be connected to both the slave and master frequency converters respectively, and the controller can be connected to the master frequency converter, or the controller can be connected to both the master and slave frequency converters.

[0154] In addition, Figure 4 Only the more critical components are shown in the diagram. Other necessary components, such as contactors and capacitors, are not shown. In addition, the controller 300 can also be connected to the traction motor 420. In one example, it can be connected to the first motor and the second motor respectively, and obtain the speed information of the first motor and the second motor.

[0155] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of this disclosure. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0156] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A control method for a coal mining machine traction system, characterized in that, The method is applied to the controller in the traction system of a coal mining machine. The system includes a frequency converter, a traction motor, and the controller. The frequency converter is used to receive three-phase AC power from the transformer and rectifies the three-phase AC power through a rectifier module before inputting it into an inverter module through a DC bus to control the operation of the traction motor. The method includes: Real-time monitoring of the voltage value of the DC bus; In response to the voltage value being lower than a first preset threshold, voltage fluctuation information within a preset time period is acquired; The predicted duration of the DC bus undervoltage is determined based on the voltage fluctuation information and compared with the first target duration. If the predicted duration is determined to be less than the first target duration, the output frequency of the inverter is controlled according to the voltage fluctuation information to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce its speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage. The coal mining machine traction system further includes a supplementary power generation device, which is connected to the controller and the rectifier module of the frequency converter. The method includes: If it is determined that the predicted duration is longer than the second target duration and / or the voltage value is lower than the second preset threshold, the inverter is controlled to stop working. The second target duration is determined based on the first target duration and the power generation capacity of the supplementary power generation device. If it is determined that the predicted duration is greater than the first target duration and less than the second target duration, the supplementary power generation device is controlled to start. In response to the next adjustment cycle of the PID control, the speed of the traction motor will be adjusted to be less than or equal to a preset speed threshold, and the output frequency of the inverter will be controlled to maintain the speed of the traction motor at the preset speed threshold; and, Based on the voltage fluctuation information, the supplementary power generation device is controlled to output three-phase AC power to the rectifier module, so that the power generated by the supplementary power generation device is supplemented to the DC bus through the rectifier module to maintain the DC bus voltage.

2. The method according to claim 1, characterized in that, The method includes: Based on historical undervoltage data, generate multiple historical fluctuation vectors and store them locally; The step of determining the predicted duration of the DC bus undervoltage based on the voltage fluctuation information includes: Based on the voltage fluctuation information, a voltage fluctuation vector is generated; Calculate the similarity distance between the voltage fluctuation vector and the plurality of historical fluctuation vectors; The historical fluctuation vector that is closest to the voltage fluctuation vector is determined based on the similarity distance; Based on the historical undervoltage data, the historical duration corresponding to the historical fluctuation vector is determined, and the predicted duration is obtained.

3. The method according to claim 1, characterized in that, The method includes: The first target duration is determined based on the current voltage value and the current speed of the traction motor.

4. The method according to claim 3, characterized in that, The first target duration is determined based on the current voltage value and the current speed of the traction motor, including: Determine the initial difference speed based on the current voltage value and the target voltage value; Based on the initial difference speed and the current speed, the time required to adjust the traction motor to zero is determined, thus obtaining the first target time.

5. The method according to claim 1, characterized in that, The method includes: If it is determined that the speed of the traction motor will be adjusted to less than or equal to zero in the next adjustment cycle of the PID regulation, and / or the voltage value is lower than the second preset threshold, a DC bus voltage low fault information is sent, and the voltage fluctuation information within the preset time period is stored as historical undervoltage data.

6. The method according to any one of claims 1-5, characterized in that, The method includes: In response to the DC bus undervoltage recovery, the output frequency of the inverter is increased to the preset frequency before the DC bus undervoltage.

7. The method according to claim 1, characterized in that, The frequency converter includes a slave frequency converter and a master frequency converter, and the traction motor includes a first motor connected to the master frequency converter and a second motor connected to the slave frequency converter. The step of controlling the output frequency of the frequency converter based on the voltage fluctuation information includes: The output frequency of the inverter master is controlled according to the voltage fluctuation information, so that the inverter slave changes in response to the change of the output frequency of the inverter slave.

8. A control device for a coal mining machine traction system, characterized in that, The control device is applied to the controller of the coal mining machine traction system. The system includes a frequency converter, a traction motor and the controller. The frequency converter is used to receive three-phase AC power from the transformer and rectifies the three-phase AC power through the rectifier module and inputs it to the inverter module through the DC bus to control the operation of the traction motor. The control device includes: The detection module is used to detect the voltage value of the DC bus in real time; The acquisition module is used to acquire voltage fluctuation information within a preset time period in response to the voltage value being lower than a first preset threshold. The prediction module is used to determine the predicted duration of the DC bus undervoltage based on the voltage fluctuation information and compare it with the first target duration. The control module is used to control the output frequency of the inverter according to the voltage fluctuation information when it is determined that the predicted duration is less than the first target duration, so as to perform PID adjustment on the speed of the traction motor, thereby controlling the traction motor to reduce the speed to generate electricity and feeding the generated electricity of the traction motor back to the DC bus through the inverter module to maintain the DC bus voltage. A supplementary power generation module is connected to the controller and the rectifier module of the inverter, and is used to control the inverter to stop working when the predicted duration is greater than the second target duration and / or the voltage value is lower than the second preset threshold, wherein the second target duration is determined based on the first target duration and the power generation capacity of the supplementary power generation module; when the predicted duration is greater than the first target duration and less than the second target duration, the supplementary power generation module is controlled to start; in response to the next adjustment cycle of the PID regulation, the speed of the traction motor is adjusted to be less than or equal to a preset speed threshold, and the output frequency of the inverter is controlled to maintain the speed of the traction motor at the preset speed threshold; and according to the voltage fluctuation information, the supplementary power generation module is controlled to output three-phase AC power to the rectifier module so that the generated power of the supplementary power generation module is supplemented to the DC bus through the rectifier module to maintain the DC bus voltage.

9. A coal mining machine traction system, characterized in that, The system includes a frequency converter, a traction motor, and a controller. The frequency converter receives three-phase AC power from the transformer and rectifies the three-phase AC power through a rectifier module before inputting it into the inverter module via a DC bus to control the operation of the traction motor. The controller is used to perform the method according to any one of claims 1-7.

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