Load-sensing-based ore conveying speed-regulating energy-saving system

Abstract

The application discloses a load-sensing-based ore conveying speed-regulating energy-saving system and relates to the technical field of ore conveying speed-regulating energy-saving. The system comprises a load-sensing module which collects a pressure time sequence signal of a roller array and an encoder speed pulse signal, marks a material boundary node through inflection point detection, divides load sections and generates section identification. A load analysis module calculates a particle size distribution coefficient according to a pressure peak value interval and a peak value amplitude of each load section, corrects pressure accumulation to obtain a section net load amount, calculates a section load change rate in combination with the speed pulse signal and generates a load distribution description table. A speed-regulating decision module determines a target speed according to the maximum section net load amount and the section load change rate and generates a speed-regulating control instruction. A drive execution module adjusts an inverter output frequency and feeds back an actual output frequency to the load analysis module to update the load distribution description table. The system can improve the calculation accuracy of the section net load and the speed-regulating response capability and reduce conveying energy consumption.

Description

Technical Field

[0001] This invention relates to the field of ore conveying speed regulation and energy saving technology, specifically to an ore conveying speed regulation and energy saving system based on load sensing. Background Technology

[0002] During ore conveying, the conveyor belt typically operates at a fixed speed. However, variations in the feed rate cause the ore load on the conveyor belt to fluctuate over time. The fixed-speed method results in wasted electrical power during low-load phases. To reduce energy consumption, existing technologies use electronic belt scales or pressure sensors to acquire conveyor belt load signals and adjust the inverter output frequency based on the load magnitude. Pressure sensors are generally installed below or on the side of the idlers, collecting pressure signals from the idler array and combining them with encoder speed signals to estimate material flow or total load. The pressure signals obtained in this way include components such as material weight, conveyor belt weight, idler vibration, and conveyor belt inertia. Directly summing or averaging these pressure signals yields a load value that deviates from the actual ore weight. Furthermore, the ore distribution on the conveyor belt is discontinuous; differences in ore particle size distribution across different sections alter the time interval and amplitude characteristics of pressure peaks. However, existing load detection methods do not analyze these characteristics, making it difficult to obtain segment-level net load values. Existing speed control strategies typically rely on instantaneous load or the average load of the entire conveyor belt, failing to identify the maximum load sections or track the rate of load change within those sections. This leads to speed lag or sudden speed changes during rapid load shifts, impacting conveyor stability and energy efficiency. When generating speed control commands, current methods do not consider the load conditions near the downstream conveyor unloading point, resulting in a fixed speed change slope. When the upstream material inflow does not match the downstream receiving capacity, material accumulation or load surges in downstream equipment can easily occur. Problems to be overcome in existing technologies include: the influence of inertial force and particle size distribution in the pressure signal is not effectively corrected, leading to inaccurate section net load; speed control decisions do not consider the trend of section net load changes and downstream load conditions, resulting in a mismatch between speed adjustment and actual material distribution. Summary of the Invention

[0003] This invention provides a load-sensing-based ore conveying speed regulation and energy-saving system, which is used to obtain the section net load amount close to the actual material weight during ore conveying, determine the target speed based on the maximum section net load amount and the section load change rate, and adjust the speed change slope in combination with the unloading point status of the downstream conveyor, so that the conveying speed matches the ore load distribution and the downstream receiving capacity, thereby reducing conveying energy consumption and speed change shock.

[0004] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides an energy-saving speed regulation system for ore conveying based on load sensing, comprising a load sensing module, a load analysis module, a speed regulation decision module, and a drive execution module. The load sensing module is used to collect the pressure timing signal of the idler array and the encoder speed pulse signal, perform inflection point detection on the pressure timing signal, mark the position where the pressure difference sign reverses as a material boundary node, divide the load into sections based on the material boundary nodes, and generate section identifiers; the load analysis module is used to calculate the particle size distribution coefficient based on the pressure peak interval and peak amplitude of each load section, correct the pressure accumulation based on the particle size distribution coefficient to obtain the section net load, calculate the section load change rate based on the speed pulse signal, and generate a load distribution description table; the speed regulation decision module is used to determine the target speed according to the maximum section net load and the section load change rate, according to a preset speed regulation mapping rule, and generate a speed regulation control command; the drive execution module is used to adjust the inverter output frequency according to the speed regulation control command and feed back the actual output frequency to the load analysis module, which updates the load distribution description table based on the actual output frequency. This system uses a closed-loop coordination of load sensing, load analysis, speed regulation decision-making, and drive execution to adapt the conveyor belt speed to the actual distribution and changing trend of the ore load, thereby reducing ineffective energy consumption during light load or no-load conditions.

[0005] Preferably, the specific process of the load sensing module in detecting inflection points in the pressure time-series signal is as follows: For each sampling point, calculate the pressure difference between the pressure value at that sampling point and the pressure value at the previous sampling point; when the pressure difference changes from a positive value to a negative value or from a negative value to a positive value, mark the sampling point as a candidate boundary node; if the number of sampling points between two candidate boundary nodes is less than a preset threshold, then merge the two candidate boundary nodes into one material boundary node. This method can avoid too many material boundary nodes caused by local pressure fluctuations and improve the accuracy of load segment division.

[0006] Preferably, the process by which the load sensing module divides load segments and generates segment identifiers based on material boundary nodes is as follows: The number of the idler corresponding to each material boundary node is read; the idler spacing table is consulted based on the idler number to obtain the straight-line distance between adjacent material boundary nodes; the number of idlers between adjacent material boundary nodes is counted, and the number of idlers and the first idler number together form the segment identifier; the segment identifier is associated with the corresponding segment of pressure timing signal and stored in the segment buffer. This allows for independent storage of pressure timing signals by segment, facilitating feature extraction by the load analysis module.

[0007] Preferably, the process by which the load analysis module calculates the particle size distribution coefficient based on the pressure peak interval and peak amplitude of each load segment is as follows: The pressure time-series signal of the corresponding load segment is read from the segment buffer area; local peaks are extracted; the time point of occurrence of each local peak is recorded as the peak time, and the pressure amplitude corresponding to that peak is also recorded; the time interval between adjacent peak times is calculated as the peak interval; the variance of all peak intervals is calculated to obtain the peak interval variance; the average of all pressure amplitudes is calculated to obtain the average peak amplitude; and the pre-stored particle size distribution coefficient table is queried based on the peak interval variance and the average peak amplitude to obtain the ore particle size distribution coefficient for that load segment. Identifying the ore particle size distribution through the statistical characteristics of peak intervals and amplitudes provides a correction basis related to the actual material characteristics for net load correction.

[0008] Preferably, the process by which the load analysis module corrects the pressure accumulation to obtain the net load of a section based on the particle size distribution coefficient is as follows: From the pressure time-series signal of the corresponding load section, the sampled values ​​are accumulated over a duration to obtain the pressure accumulation; the conveyor belt acceleration is determined based on the speed pulse signal; the conveyor belt mass value corresponding to the load section is obtained from the conveyor belt mass distribution table; an inertial force correction is generated based on the conveyor belt acceleration and the conveyor belt mass value; the inertial force correction is subtracted from the pressure accumulation, and the subtraction result is corrected using the particle size distribution coefficient to obtain the net load of the section. This process can reduce the inertial force interference caused by changes in conveyor belt acceleration, while compensating for the influence of particle size distribution on the pressure accumulation, thus improving the accuracy of the net load.

[0009] Preferably, the load analysis module calculates the segment load change rate by combining the speed pulse signal as follows: Historical records of the segment net load for the same segment are read from the load distribution description table according to a fixed time window; the segment net load in the current time window is calculated by subtracting the segment net load in the previous time window; this difference, along with the fixed time window length, is used to generate the segment load change rate; the segment load change rate, along with the current segment net load, is written into the record position corresponding to the segment identifier in the load distribution description table. The load distribution description table is continuously updated with the segment net load and segment load change rate, providing real-time load change trends for speed control decisions.

[0010] Preferably, the speed control decision module determines the target speed according to the maximum section net load and the section load change rate, following a preset speed control mapping rule: It selects the record with the largest section net load value from the load distribution description table, and designates the section corresponding to this record as the maximum load section; it reads the section load change rate of the maximum load section; when the section load change rate is greater than a preset positive rate threshold, it sets the speed above the current speed level in the speed control mapping rule as the target speed; when the section load change rate is less than a preset negative rate threshold, it sets the speed below the current speed level as the target speed; when the section load change rate is between the positive and negative rate thresholds, it maintains the current speed level as the target speed. Using the maximum load section as the basis for speed control ensures that the target speed prioritizes meeting the conveying needs of the heavy-load section.

[0011] Preferably, the process by which the speed control decision module generates the speed control command is as follows: acquiring the current actual speed of the drive motor; calculating the speed difference between the target speed and the current actual speed corresponding to the target speed; determining the speed change slope based on the length of the maximum load segment and the rate of change of the segment load; encapsulating the target speed, the speed change slope, and the maximum load segment identifier into a speed control command; and sending the speed control command to the drive execution module. By controlling the speed change slope, the impact of sudden speed changes on the conveyor belt and drive device can be avoided.

[0012] Preferably, the drive execution module feeds back the actual output frequency to the load analysis module. The process of the load analysis module updating the load distribution description table is as follows: the drive execution module converts the actual output frequency of the frequency converter into the actual belt speed via the encoder and sends the actual belt speed to the load analysis module; the load analysis module receives the actual belt speed, replaces the historical belt speed in the load distribution description table with the actual belt speed, recalculates the segment load change rate of each load segment, and overwrites the updated segment load change rate into the corresponding segment identifier record. Through the feedback correction of the actual output frequency, the belt speed and load change rate in the load distribution description table are kept consistent with the actual operating state.

[0013] As a technical solution of the present invention, the speed regulation decision module obtains the load distribution description table of the downstream conveyor when determining the speed change slope; extracts the unloading point load of the section near the unloading point from the load distribution description table of the downstream conveyor, and compares the unloading point load with the maximum section net load of the current conveyor belt; if the unloading point load is greater than the maximum section net load of the current conveyor belt, the speed change slope is reduced and the execution time is extended; if the unloading point load is less than the maximum section net load of the current conveyor belt, the speed change slope remains unchanged. Introducing the load status of the downstream conveyor for speed regulation coordination can reduce the risk of congestion at the downstream unloading point caused by changes in the upstream conveyor speed.

[0014] The technical effects and advantages provided by the present invention in the above technical solution are as follows: By detecting material boundary nodes in the pressure timing signal of the idler array through pressure difference sign reversal detection, the pressure signal between adjacent boundaries is divided into independent load segments, with each segment identified by the number of idlers and the first idler's number. For each load segment, the local peak occurrence time and pressure amplitude are extracted, the variance of the time interval between adjacent peaks and the average peak amplitude are calculated, and the ore particle size distribution coefficient is obtained from a table. When calculating the pressure accumulation, the inertial force correction is first generated based on the encoder speed pulse signal to determine the conveyor belt running acceleration and the conveyor belt mass value, and then subtracted from the pressure accumulation. The particle size distribution coefficient is then used to correct the subtraction result. The resulting segment net load can eliminate the interference of conveyor belt running inertial force and ore particle size distribution on the pressure accumulation. Compared with directly integrating or averaging the pressure signal, it better reflects the actual weight of the ore in the segment, reduces load misjudgment caused by large pieces of ore or conveyor belt acceleration and deceleration, and makes the net load involved in speed adjustment decisions closer to the actual ore weight. Meanwhile, the load sensing module merges adjacent nodes with a sample number of candidate boundary nodes less than a preset threshold, avoiding overly dense segment divisions caused by instantaneous roller vibration or signal glitch, and reducing recognition fluctuations caused by overly dense segment divisions. The maximum load segment is determined based on the record with the largest net load in the load distribution description table. The segment load change rate is read and compared with positive and negative rate thresholds to select the target speed level. The segment load change rate is calculated from the difference in net load within the same segment within a fixed time window, reflecting the growth or decay trend of the segment load. Compared to judging solely based on instantaneous load, speed adjustment based on the maximum segment net load and segment load change rate allows for advance speed increase before the load rises rapidly and timely speed decrease after the load falls, reducing speed adjustment lag. When generating speed control commands, the load distribution description table of the downstream conveyor is obtained, the unloading point load of the segment near the unloading point is extracted, and compared with the maximum segment net load of the current conveyor belt. If the load at the unloading point is greater than the current maximum net load of the section, the speed change slope is reduced and the execution time is extended to prevent material accumulation at the downstream conveyor unloading point due to excessively fast material arrival. If the load at the unloading point is less than the current maximum net load of the section, the speed change slope remains unchanged. Through this speed slope adjustment method, the speed change process is matched with the downstream receiving state, reducing the impact of sudden speed changes on the conveyor belt and drive equipment, and improving the operational stability and energy-saving effect of the conveying system under different load conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 This is a schematic diagram of a load-sensing-based ore conveying speed regulation and energy-saving system. Figure 2 This is a flowchart of the net load and load change rate of the analysis section in the load analysis module; Figure 3 This is a flowchart for adjusting the slope of the speed change based on the load at the unloading point of the downstream conveyor. Figure 4 This is a schematic diagram of the idler roller pressure timing signal and material boundary node identification; Figure 5 It is a time series curve of the net load and load change rate of the load distribution section; Figure 6 It is a speed control effect curve based on the maximum section net load and the load change rate; Figure 7 It is the timing curve of the inverter output frequency and load change rate versus the actual belt speed. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] See Figure 1This invention provides an energy-saving speed control system for ore conveying based on load sensing, comprising a load sensing module, a load analysis module, a speed control decision module, and a drive execution module. The load sensing module collects pressure timing signals from the idler array and encoder speed pulse signals, performs inflection point detection on the pressure timing signals, marks the positions where the pressure difference sign reverses as material boundary nodes, divides load segments based on these material boundary nodes, and generates segment identifiers. The load analysis module calculates the particle size distribution coefficient based on the pressure peak interval and peak amplitude of each load segment, corrects the pressure accumulation based on the particle size distribution coefficient to obtain the segment net load, and calculates the segment load change rate based on the speed pulse signals to generate a load distribution description table. The speed control decision module determines the target speed according to the maximum segment net load and the segment load change rate, following a preset speed control mapping rule, and generates speed control commands. The drive execution module adjusts the inverter output frequency according to the speed control commands and feeds back the actual output frequency to the load analysis module, which updates the load distribution description table based on the actual output frequency.

[0019] In practice, the load sensing module acquires the pressure timing signal and encoder speed pulse signal from the idler array. The pressure timing signal is output by the idler array located below the conveyor belt, with each idler corresponding to a pressure sampling channel. The load sensing module reads the pressure value from the idler array according to a fixed sampling period to form the pressure timing signal. The encoder speed pulse signal is output by the encoder installed on the conveyor belt drive roller, and the load sensing module synchronously records the count value of the encoder speed pulse signal.

[0020] The load sensing module performs inflection point detection on the pressure time-series signal as follows: For each sampling point, the load sensing module calculates the pressure difference between the pressure value at the current sampling point and the pressure value at the previous sampling point. The pressure difference equals the pressure value at the current sampling point minus the pressure value at the previous sampling point. The load sensing module compares the sign of the pressure difference between the current and previous sampling points. When the pressure difference changes from positive to negative or vice versa, the load sensing module marks the current sampling point as a candidate boundary node. The load sensing module then writes the sampling point number and the reversed sign of the pressure difference corresponding to the candidate boundary node into the candidate boundary node list.

[0021] The candidate boundary node merging process is as follows: The load sensing module sequentially reads two adjacent candidate boundary nodes from the candidate boundary node list and counts the number of sampling points between the two adjacent candidate boundary nodes. In this implementation, the preset number threshold is set to 5. If the number of sampling points between two adjacent candidate boundary nodes is less than the preset number threshold, the load sensing module merges the two adjacent candidate boundary nodes into one material boundary node. The sampling point index of the material boundary node is the arithmetic mean of the sampling point indices of the two adjacent candidate boundary nodes, rounded down. If the number of sampling points between two adjacent candidate boundary nodes is greater than or equal to the preset number threshold, the load sensing module retains the candidate boundary node as a material boundary node.

[0022] The process of dividing the load segment at material boundary nodes is as follows: The load sensing module reads the number of the idler corresponding to each material boundary node. Based on the position of the sampling point number of the material boundary node in the pressure timing signal, the load sensing module queries the mapping relationship between the idler array sampling points and the idler numbers to obtain the idler number corresponding to the material boundary node. The load sensing module then queries the idler spacing table based on the idler number. The idler spacing table stores the idler number, adjacent idler numbers, and the straight-line distance between adjacent idler numbers. Starting from the idler number corresponding to the preceding material boundary node in a sequence of adjacent material boundary nodes, the load sensing module queries the idler spacing table along the increasing direction of the idler numbers and accumulates the results to obtain the straight-line distance between two adjacent material boundary nodes.

[0023] The load sensing module counts the number of idlers between two adjacent material boundary nodes. The idler count includes the idler corresponding to the next material boundary node, but excludes the idler corresponding to the previous material boundary node. The load sensing module uses the idler count and the first idler number to form a segment identifier. The first idler number is the idler number corresponding to the previous material boundary node among the two adjacent material boundary nodes. The segment identifier is a string format, concatenating the idler count and the first idler number.

[0024] The load sensing module associates the segment identifier with the corresponding pressure timing signal and stores it in the segment buffer. The corresponding pressure timing signal is the pressure timing data from the sampling point number of the previous material boundary node to the sampling point number of the next material boundary node between two adjacent material boundary nodes. The load sensing module uses the segment identifier as an index to write the pressure timing data into the segment buffer. In specific implementations, the segment buffer is implemented using a pre-allocated data buffer in memory.

[0025] See Figure 4In the graph, the horizontal axis represents the sampling point number, the left side of the vertical axis represents the pressure value in Newtons, and the right side of the vertical axis represents the encoder pulse count value. The solid blue curve represents the idler roller pressure timing signal, while the orange dashed line and green dotted line represent the pressure timing signals of adjacent and far-end idlers, respectively. The red solid curve represents the encoder speed pulse signal, whose value remains in two relatively high and stable ranges in the graph, reflecting the state of the conveyor belt operating at different speed levels.

[0026] In the scatter plot, purple triangles represent candidate boundary nodes, which are inflection points detected by the inversion of the pressure difference sign. The candidate boundary nodes in the figure are periodically distributed. Brown dots represent material boundary nodes after merging, which are fewer in number than candidate boundary nodes and are evenly distributed near pressure peaks and troughs, marking the boundary position of the material block and effectively dividing the load section.

[0027] The trend of the blue idler roller pressure timing signal curve shows multiple distinct periodic peaks and troughs, with peak values ​​approaching 200 Newtons and trough values ​​approaching 0 Newtons. This indicates significant fluctuations in the pressure of the material carried by the idler roller, reflecting the periodic passage of material blocks. The pressure changes in the orange and green curves are synchronized with the main idler roller pressure but with slightly different amplitudes, reflecting the load transfer characteristics of adjacent and distant idler rollers.

[0028] The encoder speed pulse signal red curve shows obvious step changes at sampling points approximately 150 and 480, jumping from about 100 pulses to about 150 pulses, and then to about 180 pulses, indicating the switching process of the current conveyor belt speed level. The speed level change is superimposed on the load pressure fluctuation, reflecting the system's speed regulation mechanism that adjusts the conveyor belt speed according to load changes.

[0029] In specific implementation, please refer to Figure 2 The load analysis module reads the pressure timing signal of the corresponding load segment from the segment buffer. The pressure timing signal consists of a sequence of pressure values ​​arranged in chronological order of sampling time, with each pressure value corresponding to a sampling point. The load analysis module performs local peak extraction on the pressure timing signal. Local peak extraction uses a sliding window comparison method, with the local peak extraction window length set to 7 sampling points. Starting from the 4th sampling point of the pressure timing signal and ending at the 4th sampling point from the end, the load analysis module compares the pressure value of each sampling point with the pressure values ​​of the other 6 sampling points within the local peak extraction window. If the pressure value of the current sampling point is greater than the pressure values ​​of the other 6 sampling points within the local peak extraction window, the load analysis module marks the current sampling point as a local peak. The load analysis module records the time point at which each local peak occurs as the peak time, which is the sampling time of the sampling point corresponding to the local peak. The load analysis module records the pressure amplitude corresponding to each local peak, which is the pressure value of the sampling point corresponding to the local peak.

[0030] The load analysis module calculates the time interval between adjacent peak times as the peak interval. The peak interval is the difference between the peak time of the subsequent local peak and the peak time of the preceding local peak. The load analysis module calculates the variance of all peak intervals to obtain the peak interval variance. The peak interval variance is calculated according to the following formula: in, Indicates the variance of the peak interval; This represents the total number of local peaks; The index indicating the peak interval. The value range is from 1 to ; Indicates the first Peak intervals; This represents the average of all peak intervals. Divide by the sum of all peak intervals The load analysis module calculates the average peak amplitude by averaging all pressure amplitudes. The average peak amplitude is obtained by summing the pressure amplitudes corresponding to all local peaks and dividing by . get.

[0031] The load analysis module queries a pre-stored particle size distribution coefficient table based on the peak interval variance and the average peak amplitude. The particle size distribution coefficient table is stored in the read-only memory within the load analysis module. The first dimension of the particle size distribution coefficient table is the peak interval variance interval, and the second dimension is the average peak amplitude interval. A particle size distribution coefficient is stored at the intersection of each peak interval variance interval and the average peak amplitude interval. The load analysis module first matches the peak interval variance with the peak interval variance intervals in the particle size distribution coefficient table to determine the peak interval variance interval into which the peak interval variance falls. Then, the load analysis module matches the average peak amplitude with the average peak amplitude intervals in the particle size distribution coefficient table to determine the average peak amplitude interval into which the average peak amplitude falls. The load analysis module reads the particle size distribution coefficient at the intersection of the determined peak interval variance interval and the determined average peak amplitude interval, using it as the particle size distribution coefficient for that load segment.

[0032] The load analysis module accumulates the sampled values ​​from the pressure time-series signal of the corresponding load segment over a duration to obtain the pressure accumulation. The pressure accumulation is calculated as follows: the load analysis module reads the pressure value of each sampling point within the load segment, multiplies the pressure value of each sampling point by the sampling period to obtain the pressure integral value of the sampling point, and then accumulates the pressure integral values ​​of all sampling points within the load segment. The accumulated result is used as the pressure accumulation.

[0033] The load analysis module determines the conveyor belt's running acceleration based on the speed pulse signal. The module reads the pulse count values ​​from the encoder speed pulse signal for two adjacent sampling periods within the start and end time range of the load section. The conveyor belt's running acceleration is obtained by subtracting the pulse count value from the previous sampling period's pulse count value in the later sampling period and dividing the result by the square of the sampling period.

[0034] The load parsing module retrieves the conveyor belt mass value corresponding to the load segment from the conveyor belt mass distribution table. The conveyor belt mass distribution table is stored in the non-volatile memory within the load parsing module. The table contains a segment identifier field and a conveyor belt mass value field. Using the segment identifier corresponding to the load segment as the query condition, the load parsing module searches the conveyor belt mass distribution table for records matching the segment identifier, and reads the value from the conveyor belt mass value field of the matching record as the conveyor belt mass value corresponding to the load segment.

[0035] The load analysis module generates an inertial force correction based on the conveyor belt's running acceleration and mass. The inertial force correction is equal to the product of the conveyor belt's mass and its running acceleration. The load analysis module subtracts the inertial force correction from the accumulated pressure, obtaining the accumulated pressure after deducting the inertial force. The load analysis module then uses the ore particle size distribution coefficient to correct the accumulated pressure after deducting the inertial force. The correction method involves multiplying the accumulated pressure after deducting the inertial force by the ore particle size distribution coefficient to obtain the net load of the section.

[0036] When calculating the rate of change of load in a section using the velocity pulse signal, the load analysis module reads the historical records of the net load of the same section from the load distribution description table according to a fixed time window. The fixed time window length is set to 10 seconds. The load distribution description table is stored in the memory of the load analysis module and includes a section identifier field, a section net load field, a section load change rate field, and a historical belt speed field. The load analysis module reads the section net load of the current time window and the section net load of the previous time window. The load analysis module calculates the difference between the section net load of the current time window and the section net load of the previous time window to obtain the section net load difference value. The load analysis module uses the section net load difference value and the fixed time window length to generate the section load change rate, which is equal to the section net load difference value divided by the fixed time window length.

[0037] The load parsing module writes the section load change rate along with the current section net load into the record corresponding to the section identifier in the load distribution description table. Based on the section identifier corresponding to the load section, the load parsing module locates the record in the load distribution description table whose section identifier field matches the section identifier of the load section. It then writes the current section net load into the section net load field of that record and the section load change rate into the section load change rate field of that record.

[0038] See Figure 5 In the figure, the horizontal axis represents the sampling point number, the left side of the vertical axis represents the net load of the section in tons, and the right side of the vertical axis represents the section load change rate and pressure accumulation in tons / second and Newton-second, respectively. The blue solid line, orange dashed line, and green dotted line represent the net load of sections A, B, and C, respectively; the red solid line represents the section load change rate; and the purple dotted line represents the pressure accumulation.

[0039] As shown in the figure, the net load of each section fluctuates periodically among the three sections. The net load of section B is consistently higher than that of sections A and C, while section C has the lowest net load, indicating that section B has a heavier load and section C has a lighter load. The fluctuation range of the net load in each section is significant, reflecting the changing trend of material distribution on the idler roller array.

[0040] The section load change rate curve is a solid red line, which remains basically near zero without significant fluctuations. This indicates that the load change rate is stable and the value is close to zero, which meets the requirements of the load analysis module in this embodiment for calculating the section load change rate and hysteresis control, thus avoiding frequent speed gear switching.

[0041] The pressure accumulation curve (purple dotted line) shows a stable periodic change with a small amplitude, indicating that the integral of the pressure time series signal is stable and the pressure accumulation is consistent with the change trend of the section net load, verifying the effectiveness of pressure accumulation as a load characterization parameter.

[0042] In practice, the speed control decision module selects the record with the largest net load value for a given section from the load distribution description table. The load distribution description table is stored in a memory area accessible to the speed control decision module. Each row in the load distribution description table contains a section identifier field, a section net load field, and a section load change rate field. The speed control decision module iterates through all records in the load distribution description table, compares the section net load field values ​​of each row, and determines the record with the largest net load value. The speed control decision module uses the section identifier corresponding to this record as the maximum load section identifier, and the section corresponding to this record is designated as the maximum load section.

[0043] The speed control decision module reads the rate of change of the load in the maximum load segment. It compares this rate of change with preset positive and negative rate thresholds. The positive rate threshold is set to +0.5 tons / second, and the negative rate threshold is set to -0.5 tons / second. These thresholds are stored in the configuration parameter area of ​​the speed control decision module. They form a speed control hysteresis loop to prevent frequent speed gear switching when the rate of change of the load in the segment fluctuates near zero.

[0044] When the rate of change of the section load exceeds a preset positive rate threshold, the speed control decision module uses the previous speed gear in the speed control mapping rules as the target speed. When the rate of change of the section load is less than a preset negative rate threshold, the speed control decision module uses the next lower speed gear as the target speed. When the rate of change of the section load is between the positive and negative rate thresholds, the speed control decision module maintains the current speed gear as the target speed.

[0045] The speed regulation mapping rules are stored in the read-only memory of the speed regulation decision module. Each speed regulation mapping rule contains multiple speed gears, and each speed gear corresponds to a target speed value. The speed regulation decision module internally stores the current speed gear index, which is determined by the target speed gear generated in the previous speed regulation decision. The speed regulation decision module updates the current speed gear index after each generation of a target speed gear. The speed regulation decision module locates the current speed gear in the speed regulation mapping rules based on the current speed gear index. The target speed is the target speed value corresponding to the previous or next speed gear in the speed regulation mapping rules. In specific implementations, the speed regulation mapping rules contain five speed gears, with speed gear indices from 1 to 5, and target speed values ​​set sequentially to 1.0 m / s, 1.5 m / s, 2.0 m / s, 2.5 m / s, and 3.0 m / s.

[0046] When the speed control decision module generates a speed control command, it obtains the current actual speed of the drive motor from the drive execution module. The current actual speed of the drive motor is calculated by the drive execution module based on the encoder speed pulse signal. The calculation method is: the current actual speed of the drive motor equals the pulse frequency of the encoder speed pulse signal output divided by the number of pulses per encoder revolution, then multiplied by 60. The speed control decision module calculates the target speed corresponding to the target speed. The target speed equals the target speed multiplied by the reduction ratio divided by the drive roller radius. The reduction ratio is the transmission ratio between the drive motor and the drive roller, and the drive roller radius is stored in the configuration parameters of the speed control decision module. The speed control decision module calculates the speed difference between the target speed and the current actual speed of the drive motor. The speed difference equals the target speed minus the current actual speed of the drive motor.

[0047] The speed control decision module determines the speed change slope based on the length of the maximum load section and the rate of change of the load in that section. The speed change slope is calculated using the following formula: in, Indicates the slope of the velocity change; This indicates the length of the maximum load segment, which is obtained by the load sensing module based on the straight-line distance between adjacent material boundary nodes. Indicates the rate of change of load in the section; Represents the absolute value of the rate of change of load in a section; The speed change slope adjustment coefficient is expressed in tons per second (t·s). It is stored in the parameter table of the speed control decision module. The value range of the speed change slope adjustment coefficient is 1.0 to 5.0 t·s. The speed change slope adjustment coefficient is obtained by calibrating the rated torque response time of the drive motor. In this embodiment, the speed change slope adjustment coefficient is set to 2.0 t·s, based on the rated torque response time of the drive motor being 0.5 seconds. Setting the speed change slope adjustment coefficient to 2.0 t·s allows the target speed adjustment process to be completed within 1.0 second.

[0048] The speed control decision module encapsulates the target speed, speed change slope, and maximum load segment identifier into a speed control command. The speed control command includes the target speed field, speed change slope field, and maximum load segment identifier field. The speed control decision module sends the speed control command to the drive execution module, which then adjusts the inverter's output frequency upon receiving the command.

[0049] See Figure 6 In the graph, the horizontal axis represents time in seconds, ranging from 0 to 600 seconds. The left vertical axis represents velocity in meters per second, corresponding to the blue and orange curves; the right vertical axis represents load and load change rate in tons and tons per second, corresponding to the green dashed line and red dotted line, respectively.

[0050] The blue solid line represents the target speed level output by the speed control decision module, which increases in a stepped manner. The speed levels are 1.0 m / s, 1.5 m / s, 2.0 m / s, 2.5 m / s, and 3.0 m / s, respectively, which conforms to the setting of five speed levels in the speed control mapping rule in this embodiment. The duration of each level is approximately equal, reflecting the process by which the speed control decision module adjusts the target speed according to the net load and load change rate of different load sections.

[0051] The orange curve represents the actual belt speed after the drive execution module adjusts according to the speed control command. In the initial stage, it fluctuates around 1.0 m / s. Subsequently, as the target speed gear increases, the actual belt speed gradually increases. The overall trend changes synchronously with the target speed gear, but there is a certain dynamic response time and small fluctuations, which meets the adjustment characteristics of the difference between the target speed and the actual speed in this embodiment.

[0052] The green dashed line represents the maximum net load of the section, which fluctuates periodically between approximately 15 and 25 tons. This illustrates the dynamic changes in the load sensing module's calculation of material boundary nodes and net load based on the idler roller pressure timing signal, consistent with the selection of the maximum load section in this embodiment. Changes in the maximum load significantly affect the adjustment of the target speed level, demonstrating the system's sensitive response to load variations.

[0053] The red dotted line represents the rate of change of load in the section, which remains stable within the range of -0.5 tons / second to +0.5 tons / second. This conforms to the speed regulation hysteresis range formed by the preset positive and negative rate thresholds in this embodiment, avoiding frequent speed gear switching. When the load change rate is within this hysteresis range, the target speed gear remains unchanged. The step-shaped change of the target speed gear in the figure is triggered when the load change rate exceeds the threshold.

[0054] In practical implementation, after the drive execution module adjusts the inverter's output frequency, the actual output frequency of the inverter is output from the inverter's analog feedback port. The drive execution module reads the actual output frequency of the inverter through the analog acquisition channel. The drive execution module synchronously acquires the encoder speed pulse signal, which is output by the encoder installed at the end of the drive drum shaft. The encoder outputs a fixed number of pulses per revolution.

[0055] The drive execution module calculates the encoder pulse frequency. The encoder pulse frequency is the number of pulses output by the encoder per unit time. The drive execution module sets the unit time to 1 second, records the number of encoder speed pulse signals within 1 second using a counter, and uses the number of pulses as the encoder pulse frequency.

[0056] The drive execution module calculates the actual belt speed based on the encoder pulse frequency. The actual belt speed is calculated using the following formula: in, This indicates the actual belt speed, expressed in meters per second. This indicates the encoder pulse frequency, measured in Hertz (Hz). This represents pi, with a value of 3.1415926. This indicates the diameter of the drive roller, in meters. The diameter of the drive roller is stored in the parameter memory of the drive execution module. This indicates the number of pulses per encoder revolution, measured in pulses per revolution. The number of pulses per encoder revolution is determined by the encoder model and is stored in the parameter memory of the drive execution module.

[0057] After calculating the actual belt speed, the drive execution module encapsulates the actual belt speed into a belt speed feedback message, which includes the actual belt speed field and the generation time field. The drive execution module then sends the belt speed feedback message to the load parsing module via the internal communication bus.

[0058] After receiving the belt speed feedback message, the load analysis module reads the value of the actual belt speed field from the feedback message to obtain the actual belt speed. The load analysis module then reads the load distribution description table. Each record in the load distribution description table contains a segment identifier field, a historical belt speed field, a segment net load field, and a segment load change rate field. The load analysis module replaces the value of the historical belt speed field in each record of the load distribution description table with the actual belt speed, writing the actual belt speed into the historical belt speed field.

[0059] The load analysis module recalculates the rate of change of load for each load segment. It calculates the passage time of the load segment based on the actual belt speed and the straight-line distance of the load segment; the passage time is the straight-line distance of the load segment divided by the actual belt speed. The module reads the historical net load records for the same segment, uses the passage time as the new time window length, and calculates the difference between the net load in the current time window and the net load in the previous time window. Finally, the module divides this net load difference by the passage time to obtain the recalculated rate of change of load.

[0060] The load parsing module overwrites the recalculated segment load change rate into the segment load change rate field of the corresponding segment identifier record in the load distribution description table. The load parsing module iterates through each record in the load distribution description table, writes the updated segment load change rate into the segment load change rate field of the corresponding segment identifier record, and completes the update of the load distribution description table.

[0061] See Figure 7 In the graph, the horizontal axis represents time in seconds, the left side of the vertical axis represents the inverter output frequency and actual belt speed in Hertz and meters per second, respectively, and the right side of the vertical axis represents the section load change rate in tons per second. The legend shows four curves: inverter output frequency (blue solid line), actual belt speed (orange dashed line), section load change rate before update (green dashed line), and section load change rate after update (red dotted line).

[0062] The curve shows that the inverter's output frequency underwent multiple stages of adjustment over the entire 600 seconds: In the initial stage (approximately 0-100 seconds), the inverter's output frequency stabilized at around 50Hz; from 200 to 350 seconds, the frequency decreased to approximately 45Hz, representing the first stage of deceleration; from 350 to 450 seconds, the frequency rapidly increased to approximately 60Hz, entering the second stage of acceleration; and from 450 to 600 seconds, the frequency decreased again to approximately 53Hz, entering the third stage of deceleration. This segmented change corresponds to the process by which the speed control decision module adjusts the target speed based on the load change rate within the maximum load segment.

[0063] The actual belt speed curve shows an overall trend consistent with the inverter output frequency, but the value is significantly lower than the inverter frequency value, and the change is relatively gradual. The belt speed is maintained between approximately 1.5 and 1.8 m / s in each stage, reflecting the feedback result of the drive execution module adjusting the belt speed according to the inverter frequency.

[0064] The rate of change of load in the section is shown by two curves: before the update (green dashed line) and after the update (red dotted line). Both curves exhibit periodic fluctuations, ranging from approximately -0.6 tons / second to +0.6 tons / second. The trends of the rate of change before and after the update are basically consistent, but the fluctuation amplitude of the curve after the update is smaller, and the curve is smoother. This indicates that in this embodiment, after the drive execution module feeds back the actual belt speed, the load analysis module recalculates the rate of change of load using the actual belt speed, eliminating the fluctuations introduced by the belt speed change, making the load rate of change data more accurate and stable.

[0065] The positive and negative rate thresholds of the load change rate curve in the figure are approximately +0.5 tons / second and -0.5 tons / second, respectively. The speed control decision module adjusts the inverter output frequency based on these thresholds to achieve acceleration or deceleration control. As can be seen in the figure, the increase and decrease phases of the inverter output frequency clearly correspond to the moments when the load change rate crosses the threshold, demonstrating the system's dynamic response capability in making speed control decisions based on the load change rate.

[0066] In specific implementation, please refer to Figure 3When determining the speed change slope, the speed control decision module obtains the load distribution description table of the downstream conveyor. This table is stored in the downstream conveyor's speed control decision module, which is connected to it via an industrial Ethernet network. The current conveyor's speed control decision module sends a load distribution description table request command to the downstream conveyor's speed control decision module. This command includes a downstream conveyor identifier field, a request data range start field, and a request data range end field. The downstream conveyor's speed control decision module responds to the request command by sending its load distribution description table to the current conveyor's speed control decision module via the industrial Ethernet network. The current conveyor's speed control decision module receives the downstream conveyor's load distribution description table and stores it in its memory buffer.

[0067] The speed control decision module extracts the unloading point load of the section near the unloading point from the load distribution description table of the downstream conveyor. Each record in the load distribution description table of the downstream conveyor contains a downstream section identifier field, a downstream section net load field, and a downstream section load change rate field. The section near the unloading point is the load section on the downstream conveyor corresponding to the current unloading position of the conveyor belt. The speed control decision module reads the coordinates of the intersection point between the centerline of the unloading chute and the bearing surface of the downstream conveyor, and queries the idler roller spacing table of the downstream conveyor based on the intersection point coordinates to determine the downstream section identifier closest to the intersection point coordinates. The speed control decision module searches for a record in the load distribution description table of the downstream conveyor whose downstream section identifier field is the same as the determined downstream section identifier, and uses the value of the downstream section net load field in that record as the unloading point load.

[0068] The speed control decision module compares the unloading point load with the current maximum segment net load of the conveyor belt. The current maximum segment net load is obtained by the speed control decision module from the load distribution description table of the current conveyor belt, selecting the record with the largest segment net load value, and the current maximum segment net load is used as the comparison benchmark.

[0069] During the comparison process, the speed control decision module calculates the speed change slope adjustment coefficient. The speed change slope adjustment coefficient is calculated according to the following formula: in, This represents the adjustment coefficient for the slope of the velocity change; it is dimensionless. This indicates the unloading point load, in tons. This indicates the maximum net load capacity of the current section of the conveyor belt, in tons.

[0070] If the unloading point load is greater than the maximum net load of the current conveyor belt section, that is... If the value is greater than 1, the speed control decision module will reduce the speed change slope. The speed control decision module obtains the original speed change slope, which is calculated by the speed control decision module based on the length of the maximum load segment and the rate of change of the segment load. The original speed change slope is stored in the slope register of the speed control decision module. The speed control decision module divides the original speed change slope by the speed change slope adjustment coefficient to obtain the reduced speed change slope. The reduced speed change slope is used to generate subsequent speed control commands.

[0071] The speed control decision module simultaneously extends the execution time. The execution time is the allowable time for the drive execution module to adjust the drive motor from the current actual speed to the target speed. The extension ratio of the execution time is equal to the speed change slope adjustment coefficient. The speed control decision module multiplies the original execution time by the speed change slope adjustment coefficient to obtain the extended execution time. The original execution time is stored in the execution time register of the speed control decision module, and is obtained by dividing the speed difference between the target speed and the current actual speed by the original speed change slope. The speed control decision module writes the extended execution time into the execution time field of the speed control command.

[0072] If the unloading point load is less than the maximum net load of the current conveyor belt section, that is... If the value is less than 1, the speed control decision module maintains the speed change slope unchanged. The speed control decision module does not modify the original speed change slope and continues to use it as the speed change slope. The speed control decision module maintains the original execution time unchanged and does not extend the execution time. The speed control decision module writes the original speed change slope into the speed change slope field of the speed control command and writes the original execution time into the execution time field of the speed control command.

[0073] After comparing the unloading point load with the current maximum section net load of the conveyor belt and adjusting the speed change slope and execution time, the speed control decision module encapsulates the target speed, the adjusted speed change slope or the original speed change slope, the extended execution time or the original execution time, and the maximum load section identifier into a speed control command. The speed control decision module sends the speed control command to the drive execution module. The drive execution module adjusts the inverter output frequency according to the values ​​of the speed change slope field and the execution time field in the speed control command, and completes the speed adjustment according to the speed change slope corresponding to the speed change slope field and the execution time corresponding to the execution time field.

[0074] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A load-sensing-based ore conveying speed regulation and energy-saving system, characterized in that, include: The load sensing module is used to collect the pressure timing signal and encoder speed pulse signal of the idler array, perform inflection point detection on the pressure timing signal, mark the position where the pressure difference sign is reversed as the material boundary node, divide the load segment according to the material boundary node and generate segment identifier; The load analysis module is used to calculate the particle size distribution coefficient based on the pressure peak interval and peak amplitude of each load section, correct the pressure accumulation based on the particle size distribution coefficient to obtain the net load of the section, calculate the load change rate of the section by combining the velocity pulse signal, and generate a load distribution description table. The speed control decision module is used to determine the target speed according to the maximum net load of the section and the rate of change of the section load, and generate speed control commands according to the preset speed control mapping rules. The drive execution module is used to adjust the output frequency of the frequency converter according to the speed control command and feed back the actual output frequency to the load analysis module. The load analysis module updates the load distribution description table according to the actual output frequency.

2. The ore conveying speed regulation and energy-saving system based on load sensing according to claim 1, characterized in that, The specific process by which the load sensing module detects inflection points in the pressure time-series signal is as follows: For each sampling point, calculate the pressure difference between the pressure value at that sampling point and the pressure value at the previous sampling point; when the pressure difference changes from a positive value to a negative value or from a negative value to a positive value, mark that sampling point as a candidate boundary node; If the number of sampling points between two candidate boundary nodes is less than a preset threshold, the two candidate boundary nodes will be merged into one material boundary node.

3. The ore conveying speed regulation and energy-saving system based on load sensing according to claim 2, characterized in that, The process by which the load sensing module divides load segments and generates segment identifiers based on material boundary nodes is as follows: Read the number of the idler corresponding to each material boundary node, and look up the idler spacing table based on the idler number to obtain the straight-line distance between adjacent material boundary nodes; Count the number of idlers between adjacent material boundary nodes, and use the number of idlers and the first idler number to form a segment identifier; Associate the segment identifier with the corresponding pressure timing signal and store it in the segment buffer.

4. The load-sensing-based ore conveying speed regulation and energy-saving system according to claim 3, characterized in that, The process by which the load analysis module calculates the particle size distribution coefficient based on the pressure peak interval and peak amplitude of each load segment is as follows: Read the pressure timing signal of the corresponding load segment from the segment buffer area, extract the local peaks, record the time point of occurrence of each local peak as the peak time, and record the pressure amplitude corresponding to the peak. The time interval between adjacent peak times is calculated as the peak interval. The variance of all peak intervals is obtained by taking the variance of all peak intervals. The average peak amplitude is obtained by taking the average of all pressure amplitudes. The ore particle size distribution coefficient for this load zone is obtained by querying the pre-stored particle size distribution coefficient table based on the peak interval variance and the average peak amplitude.

5. The load-sensing-based ore conveying speed regulation and energy-saving system according to claim 4, characterized in that, The process by which the load analysis module corrects the pressure accumulation based on the particle size distribution coefficient to obtain the net load of the section is as follows: The pressure accumulation is obtained by accumulating the sampled values ​​from the pressure time sequence signal of the corresponding load section over the duration. The conveyor belt running acceleration is determined based on the speed pulse signal. The conveyor belt mass value corresponding to the load section is obtained from the conveyor belt mass distribution table. An inertial force correction amount is generated based on the conveyor belt running acceleration and the conveyor belt mass value. The inertial force correction is subtracted from the pressure accumulation, and then the particle size distribution coefficient is used to correct the subtraction result to obtain the section net load.

6. The ore conveying speed regulation and energy-saving system based on load sensing according to claim 5, characterized in that, The load analysis module calculates the rate of change of load in a section by combining the velocity pulse signal as follows: According to the fixed time window, the historical records of the net load of the same segment are read from the load distribution description table. The difference between the net load of the segment in the current time window and the net load of the segment in the previous time window is calculated. The segment load change rate is generated using this difference and the fixed time window length. Write the section load change rate along with the current section net load into the record position corresponding to the section identifier in the load distribution description table.

7. The load-sensing-based ore conveying speed regulation and energy-saving system according to claim 6, characterized in that, The speed regulation decision module determines the target speed according to the maximum net load of the section and the rate of change of the section load, following a preset speed regulation mapping rule: Select the record with the largest net load value from the load distribution description table, and take the section corresponding to the record as the maximum load section. Read the rate of change of the load in the maximum load section. When the rate of change of the load in the section is greater than the preset positive rate threshold, take the previous speed gear in the speed regulation mapping rule as the target speed. When the rate of change of the section load is less than the preset negative rate threshold, the next speed gear will be used as the target speed. When the rate of change of the section load is between the positive rate threshold and the negative rate threshold, the current speed setting is maintained as the target speed.

8. The load-sensing-based ore conveying speed regulation and energy-saving system according to claim 7, characterized in that, The process by which the speed control decision module generates speed control commands is as follows: Obtain the current actual speed of the drive motor, and calculate the speed difference between the target speed and the current actual speed corresponding to the target speed; The velocity change slope is determined based on the length of the maximum load section and the rate of change of the load in the section. The target rotational speed, speed change slope, and maximum load segment identifier are encapsulated into speed control commands, which are then sent to the drive execution module.

9. The ore conveying speed regulation and energy-saving system based on load sensing according to claim 8, characterized in that, The drive execution module feeds back the actual output frequency to the load analysis module, and the process by which the load analysis module updates the load distribution description table is as follows: The drive execution module converts the actual output frequency of the frequency converter into the actual belt speed through the encoder, and sends the actual belt speed to the load analysis module; After receiving the actual belt speed, the load analysis module replaces the historical belt speed in the load distribution description table with the actual belt speed, recalculates the segment load change rate of each load segment, and writes the updated segment load change rate into the corresponding segment identifier record.

10. The ore conveying speed regulation and energy-saving system based on load sensing according to claim 8, characterized in that, When the speed regulation decision module determines the slope of the speed change, it obtains a load distribution description table of the downstream conveyor. Extract the unloading point load of the section near the unloading point from the load distribution description table of the downstream conveyor, and compare the unloading point load with the maximum section net load of the current conveyor belt. If the load at the unloading point is greater than the maximum net load of the current conveyor belt section, the slope of the speed change will be reduced and the execution time will be extended. If the load at the unloading point is less than the maximum net load of the current conveyor belt section, then the slope of the speed change remains unchanged.

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