Method and system for controlling power winding drum of stacker-reclaimer based on position detection

Abstract

The invention discloses a stacker-reclaimer power drum control method and system based on position detection, and the method comprises the steps: setting a cable leading-out point on a walking path of a stacker-reclaimer, and dividing the cable leading-out point into a first region and a second region; detecting whether the stacker-reclaimer passes through a leading-out point or not through a proximity switch, generating an area state signal in combination with a bistable relay, and obtaining a cart walking direction signal; taking the area state signal and the walking direction signal as input, calling a preset position state corresponding table, and generating a rotation direction control instruction and an operation mode instruction of the drum motor; meanwhile, according to the traveling speed of the cart, the output frequency of the frequency converter is dynamically adjusted, and the motor is controlled to run in an electric state during cable winding and run in a power generation braking state during cable unwinding, so that the winding drum generates torque matched with the cable dragging direction through the magnetic coupling. The cable tension fluctuation can be reduced, the mechanical stress is reduced, the service life of the cable is prolonged, and the system safety and reliability are improved.

Description

Technical Field

[0001] This invention belongs to the field of conveying equipment control technology, and relates to a control method and system for a power drum of a stacker-reclaimer based on position detection. Background Technology

[0002] Currently, stacker-reclaimer power drum systems generally employ a unidirectional constant-speed motor drive. The power cable is led out from the ground at the middle of the stacker-reclaimer's travel track (i.e., the cable lead-out point), laid across the ground, and then connected to the power drum installed on the stacker-reclaimer. As the stacker-reclaimer reciprocates along the track, the drum passively rotates under the cable's drag force, enabling the cable winding and unwinding operations. Because the drive motor only has a single direction of rotation, it cannot actively adjust the drum's operating state according to the area where the stacker-reclaimer is located and its travel direction.

[0003] As the stacker-reclaimer moves away from the cable lead-out point, the cable is pulled out, and the drum reverses direction under external drag. At this time, although the motor is energized, it is actually in electromagnetic braking mode: the motor, connected via a magnetic coupling, rotates in the opposite direction to the drum; the motor does not output driving torque but provides damping braking force to control the cable release speed. Under this condition, the motor stator current is often higher than in normal motoring mode, and all the drag force is borne by the cable, resulting in continuous high tensile stress. Especially when the trolley travels at high speed or frequently starts and stops, the instantaneous tension increases significantly.

[0004] After prolonged operation, power cables are repeatedly subjected to asymmetrical, high-amplitude mechanical stress. This can easily lead to sheath deformation, insulation cracking, and even conductor damage. Once insulation breakdown occurs, a malfunction will result. Power cables need to be continuously and neatly wound and unwound on a reel. Any intermediate joint will cause winding jamming and stress concentration, seriously endangering operational safety. Therefore, industry standards prohibit intermediate joints. This means that the entire cable must be replaced after damage. Replacement is costly and results in prolonged downtime. This can severely impact production efficiency in continuous operation scenarios such as ports or power plants.

[0005] Furthermore, the existing system cannot sense the location, direction, and speed of the stacker-reclaimer, and therefore cannot dynamically match the rotation direction and speed of the drum. This causes severe tension fluctuations in the cable during winding and unwinding, further exacerbating fatigue damage. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention proposes a control method and system for a power drum of a stacker-reclaimer based on position detection.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a power drum control method for a stacker-reclaimer based on position detection, comprising the following steps: A cable lead-out point is set on the travel path of the stacker-reclaimer, and the travel area is divided into a first area and a second area based on this point. A proximity switch installed near the cable exit point is used to detect whether the stacker-reclaimer has passed the cable exit point, and a bistable relay is used to generate a regional status signal that represents the current area. Obtain the forward or backward movement direction signal of the large vehicle; Using the area status signal and the walking direction signal as input variables, a preset position status correspondence table is called, and the rotation direction control command and operation mode command of the drum motor are generated according to the control strategy associated with the area and direction combination configured in the correspondence table. Based on the traveling speed of the trolley, the output frequency of the drum motor inverter is dynamically adjusted according to the preset speed-frequency mapping relationship, and the working state of the motor is controlled according to the operating mode command, so that the drum generates torque that matches the cable dragging direction through the magnetic coupling.

[0008] Based on the aforementioned position detection-based power drum control method for stacker-reclaimers, this invention further proposes a position detection-based power drum control system for stacker-reclaimers, comprising: The position detection unit is used to detect whether the stacker-reclaimer has passed the cable lead-out point; The area state holding unit is used to latch the area state signal representing whether the stacker-reclaimer is located in the first area or the second area based on the output of the position detection unit. The direction recognition unit is used to acquire the travel direction signal of the stacker-reclaimer; The central control unit is connected to the area status maintenance unit and the direction recognition unit respectively. It is configured to call the position status correspondence table and generate the rotation direction control command and operation mode command of the drum motor according to the combination of the area status signal and the travel direction signal. The variable frequency drive unit is connected to the central control unit. It is used to adjust the direction of rotation of the drum motor according to the rotation direction control command, dynamically set the motor operating frequency according to the trolley travel speed, and control the working state of the motor according to the operating mode command.

[0009] Compared with existing technologies, the present invention has the following advantages: by using a frequency converter to drive the drum motor, dynamic matching between the drum speed and the stacker-reclaimer's traveling speed is achieved. When the trolley is running at low speed, the drum motor operates at a corresponding low frequency; when the trolley is running at high speed, the drum motor synchronously increases its speed, ensuring that the cable winding and unwinding rate is coordinated with the trolley displacement.

[0010] By pre-setting the frequency parameters of the inverter, the output speed of the drum can be matched under different working conditions, effectively preventing the cable from slack and piling up on the ground during the cable unwinding process or from being over-tightened during the cable rewinding process, thereby reducing the mechanical tension on the cable.

[0011] Meanwhile, the system automatically controls the drum motor to rotate forward or backward based on the area and direction of the stacker-reclaimer, allowing the drum to actively follow the movement of the trolley and reducing the continuous high stress on the cable under electromagnetic braking. This control strategy not only reduces cable wear and fatigue damage but also improves the smoothness and reliability of cable winding and unwinding, effectively extending the service life of the power cable and reducing maintenance costs and downtime. Attached Figure Description

[0012] Figure 1 This is a diagram of the region state maintenance unit and position detection hardware control loop of the present invention; Figure 2 This is a diagram of the first and second region setting and resetting logic and the drum speed control circuit of the present invention; Figure 3 This is the forward and reverse rotation control braking timing and fault protection circuit diagram of the drum motor of the present invention; Figure 4 This is a diagram showing the power wiring and control interface connection of the variable frequency drive unit of the present invention; Figure 5 This is the logic diagram of the walking distance calculation and area judgment based on the rotary encoder of the present invention; Figure 6 This is a diagram of the architecture of a power drum control system for a stacker-reclaimer based on position detection, according to the present invention. Detailed Implementation

[0013] 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, and 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.

[0014] like Figures 1-6 As shown, the technical solution adopted by the present invention is as follows: A power drum control method for a stacker-reclaimer based on position detection, comprising the following steps: A cable lead-out point is set on the travel path of the stacker-reclaimer, and the travel area is divided into a first area and a second area based on this point.

[0015] A proximity switch installed near the cable exit point is used to detect whether the stacker-reclaimer has passed the cable exit point, and a bistable relay is used to generate a regional status signal that represents the current area.

[0016] Obtain the forward or backward travel direction signal of the vehicle.

[0017] Using the area status signal and the walking direction signal as input variables, a preset position status correspondence table is called, and the rotation direction control command and operation mode command of the drum motor are generated according to the control strategy associated with the area and direction combination configured in the correspondence table.

[0018] Based on the traveling speed of the trolley, the output frequency of the drum motor inverter is dynamically adjusted according to the preset speed-frequency mapping relationship, and the working state of the motor is controlled according to the operating mode command, so that the drum generates torque that matches the cable dragging direction through the magnetic coupling.

[0019] Based on the aforementioned position detection-based power drum control method for stacker-reclaimers, this invention further proposes a position detection-based power drum control system for stacker-reclaimers, comprising: The position detection unit is used to detect whether the stacker-reclaimer has passed the cable lead-out point.

[0020] The area state holding unit is used to latch the area state signal representing whether the stacker-reclaimer is located in the first area or the second area based on the output of the position detection unit.

[0021] The direction recognition unit is used to acquire the travel direction signal of the stacker-reclaimer.

[0022] The central control unit is connected to the area status maintenance unit and the direction recognition unit, respectively. It is configured to call the position status correspondence table and generate rotation direction control commands and operating mode commands for the drum motor based on the combination of area status signals and travel direction signals.

[0023] The variable frequency drive unit is connected to the central control unit. It is used to adjust the direction of rotation of the drum motor according to the rotation direction control command, dynamically set the motor operating frequency according to the trolley travel speed, and control the working state of the motor according to the operating mode command.

[0024] Furthermore, the cable lead-out point is the physical location where the power cable exits from its fixed ground end and connects to the stacker-reclaimer. This point serves as the spatial reference origin for the entire travel path. Using the cable lead-out point as a boundary, the entire track path of the stacker-reclaimer is divided into two mutually exclusive and continuous regions: one side is called the first region, and the other side is called the second region. This division is used to distinguish the differences in cable deployment and retraction behavior of the stacker-reclaimer at different locations and forms the basis for subsequent zoning control logic judgments.

[0025] A non-contact proximity switch is installed near the cable exit point. When the trolley structure of the stacker-reclaimer passes the cable exit point, the non-contact proximity switch outputs a momentary level signal. This signal is not directly used for area determination, but is instead input as a trigger signal to the area status holding unit composed of two bistable relays.

[0026] The zone status holding unit employs a bidirectional electrical interlock structure. The normally closed contact of the second bistable relay is connected in series in the set coil circuit of the first bistable relay, and vice versa, ensuring that the two cannot be set simultaneously. When the proximity switch is activated, based on the current trolley travel direction or initial power-on position information, only one relay is set, and its output contact state serves as a stable zone status signal. For example, setting the first bistable relay indicates that the stacker-reclaimer is currently in the first zone, while setting the second bistable relay indicates that it is in the second zone. This zone status signal has memory properties, accurately representing the zone the stacker-reclaimer is in even after it has moved away from the cable lead-out point.

[0027] The travel direction signal indicates whether the stacker-reclaimer is moving forward or backward. The travel direction signal can be directly taken from the direction output of the trolley travel frequency converter. The travel direction signal is a digital signal, which, together with the area status signal (also a digital signal), forms the row and column indices of the position status mapping table. It is the fundamental logic input for the system to determine the drum's cable winding or unwinding mode.

[0028] The position status mapping table is a two-dimensional array stored in the non-volatile memory of the programmable logic controller (PLC) as a software data structure. Its row index corresponds to the region status code, the column index corresponds to the travel direction code, and the array elements are control words containing rotation direction and operating mode identifiers.

[0029] The central control unit performs a lookup operation whenever the area status signal or travel direction signal changes: using the current area status and travel direction as an index, it reads the corresponding control word and parses it into specific rotation direction control instructions and operating mode instructions.

[0030] The trolley's travel speed is provided in real time by its variable frequency drive unit, and is input to the central control unit as an analog signal or communication data. The central control unit pre-stores speed-frequency mapping relationships, such as linear function formulas. ,in This refers to the output frequency of the frequency converter for the drum motor. This refers to the speed at which the large vehicle travels; The proportional coefficient is calibrated based on the drum diameter, the number of cable winding layers, and the transmission ratio. Based on this, the output frequency of the drum motor frequency converter is dynamically calculated and set to synchronize the drum linear speed with the trolley travel speed, thus avoiding cable slack accumulation or excessive stretching.

[0031] Meanwhile, the frequency converter automatically switches its operating state according to the received operating mode command: during cable winding, the motor operates in motor mode, actively outputting positive torque to wind the cable; during cable unwinding, the motor operates in generator braking mode, generating reverse damping torque in the same direction as the cable dragging through the magnetic coupling, allowing the cable to be released smoothly without excessive tension. The magnetic coupling here plays a role in flexible transmission and overload protection, allowing a controllable slip between the motor and the drum, thereby absorbing instantaneous impacts and maintaining torque matching.

[0032] Specifically, controlling the motor's operating state according to the operating mode command includes: controlling the motor to operate in electric mode during cable winding operation, and controlling the motor to operate in generator braking mode during cable unwinding operation.

[0033] The operating mode command is a control signal generated by the central control unit after looking up the position status correspondence table. It is used to indicate which energy conversion mode the drum motor should be in.

[0034] When the operation is determined to be cable winding, the operating mode command causes the frequency converter to drive the drum motor to absorb electrical energy from the power grid and output mechanical torque. At this time, the motor is in motor mode and actively rotates to tighten the power cable.

[0035] When the operation is determined to be a cable release operation, the operating mode command causes the frequency converter to switch the motor to the generator braking state. At this time, the motor is driven to rotate by the stacker-reclaimer. Its rotor speed is higher than the synchronous speed, generating a reverse electromagnetic torque, which converts mechanical energy into electrical energy and feeds it back to the DC bus or consumes it through the braking resistor. This forms a damping torque that is consistent with the direction of cable release, preventing the cable from bearing excessive tension due to free dragging.

[0036] This judgment operation is achieved through vector control inside the frequency converter, ensuring that the motor smoothly switches between the two working states and that the torque response is dynamically matched with the movement of the trolley.

[0037] The control strategy configured in the location status correspondence table is as follows: When the stacker-reclaimer is in the first zone and its direction of travel is forward, it is determined to be a cable-laying operation.

[0038] When the stacker-reclaimer is in the first zone and moving backward, it is determined to be a cable retraction operation.

[0039] When the stacker-reclaimer is in the second zone and its direction of travel is forward, it is determined to be a cable take-up operation.

[0040] When the stacker-reclaimer is in the second zone and moving backward, it is determined to be a cable-laying operation.

[0041] Furthermore, when the stacker-reclaimer is located on one side of the cable lead-out point, i.e., in the first area, and moves (advances) away from the cable lead-out point, the power cable is gradually pulled out of the drum, thus requiring a cable release operation. At this time, the operating mode command generated by the control system causes the motor to enter a generator braking state, and the drum passively releases the cable under the action of the magnetic coupling, while providing controllable resistance to prevent the cable from loosening or piling up due to inertia.

[0042] When the stacker-reclaimer is in the first zone and moves (reverses) towards the cable lead-out point, the length of the released cable decreases, and the excess cable needs to be retrieved onto the drum. Therefore, this is considered a cable reeling operation. At this time, the operating mode command controls the motor to run in electric mode, actively rotating forward to reel in the cable, ensuring that the cable is neatly wound and avoiding dragging and wear on the ground.

[0043] When the stacker-reclaimer is located on the other side of the cable lead-out point (i.e., the second area) and continues to move forward, its actual direction of movement is towards the cable lead-out point, causing the cable length to shorten. Therefore, a cable reeling operation needs to be performed. At this time, the motor is also running in electric mode, but depending on the cable winding direction of the drum and the mechanical structure, its rotation direction may be opposite to that during cable reeling in the first area. The specific direction is coordinated by the rotation direction control command to ensure that the cable reeling action is executed correctly.

[0044] As the stacker-reclaimer moves away from the cable lead-out point in the second zone, the power cable is continuously pulled out, necessitating a cable release operation. The central control unit generates a generator braking command, causing the motor to produce a reverse torque matching the cable pulling direction. This torque is transmitted to the drum via a magnetic coupling, achieving controlled release, effectively reducing cable tension and preventing insulation breakdown due to prolonged high stress.

[0045] Specifically, the position state correspondence table is stored in the non-volatile memory of the programmable logic controller in the form of a software data structure, and is used to establish the mapping relationship between the combination of area state and walking direction and motor control actions.

[0046] The position-state mapping table is a data structure defined at the software level and permanently stored in the non-volatile memory of the programmable logic controller, ensuring that the original configuration can be retained after a power failure and restart.

[0047] The position status correspondence table establishes a one-to-one correspondence between input variables (i.e., the logical combination of area status signals and travel direction signals) and output control actions (i.e., the rotation direction indicator and operating mode indicator of the drum motor).

[0048] The region status signal indicates whether the stacker-reclaimer is currently in the first or second region, and the travel direction signal indicates whether the trolley is moving forward or backward. Together, these constitute four sets of defined input combinations. Motor control actions are specifically manifested as rotation direction control commands and operating mode commands, used to drive the variable frequency drive unit to perform corresponding operations. This mapping relationship is pre-configured and cannot be dynamically modified, ensuring the determinism and security of the control logic.

[0049] Furthermore, the position status correspondence table is implemented as a two-dimensional array, with the row index corresponding to the region status code, the column index corresponding to the walking direction code, and the array element being a control word containing a rotation direction identifier and a running mode identifier.

[0050] The position state mapping table uses a two-dimensional array data structure in the program implementation. Its row dimension is indexed by the region state code, and its column dimension by the walking direction code. The region state code is a binary discrete quantity: for example, 0 represents the first region, and 1 represents the second region. The walking direction code is also a binary discrete quantity: for example, 0 represents backward, and 1 represents forward. Although both the region state code and the walking direction code use the same binary numerical symbols 0 and 1, the region state code is only used for row indexing of the two-dimensional array, and the walking direction code is only used for column indexing. Furthermore, they are generated, transmitted, and stored by independent signal channels (for example, the region state signal is output by the region state holding unit, and the walking direction signal is output by the direction recognition unit). This avoids the risk of semantic confusion or index misalignment during program execution. This forms a 2×2 index matrix.

[0051] Each element in the array is a control word, which is a composite data type containing at least two fields: a rotation direction identifier, indicating whether the drum motor should rotate forward or backward; and an operating mode identifier, indicating whether the motor should operate in electric or regenerative braking mode. This control word serves as the direct output of the lookup result, eliminating the need for intermediate logical operations, thus improving response speed and reducing the risk of misjudgment.

[0052] When the combination of the area status signal and the travel direction signal changes, a table lookup operation is triggered, and the lookup result is parsed into rotation direction control command and operating mode command, which are then output to the drum motor frequency converter.

[0053] The central control unit continuously monitors changes in the status signals of the area and the travel direction. When any signal changes abruptly (such as the stacker-reclaimer crossing a cable exit point causing a change in the area status, or a change in the operating command causing a reversal of the travel direction), it is determined that the input combination has changed, and a table lookup operation is immediately triggered.

[0054] The table lookup operation includes: generating the corresponding area status code based on the current area status signal, generating the corresponding walking direction code based on the current walking direction signal, using these as row and column indices of a two-dimensional array, and reading the corresponding control word.

[0055] Subsequently, the central control unit parses the control word into two independent control signals: a rotation direction control command is sent to the forward or reverse start terminal of the frequency converter drive unit via a digital output port and an opto-isolation circuit. An operating mode command is transmitted to the frequency converter drive unit via a communication interface to set its internal operating mode. These commands are output synchronously to ensure that the rotation direction and operating status of the drum motor strictly match the current working conditions.

[0056] Specifically, a position detection-based control method for the power drum of a stacker-reclaimer also includes: Before calling the location status mapping table, the area status signal and the walking direction signal are verified.

[0057] If the combination is not defined in the table, it is determined to be a control logic conflict, the output of control commands is prohibited, the fault lockout relay is activated to cut off the motor enable circuit, and alarm information is output through the human-machine interface.

[0058] Furthermore, before the central control unit performs the table lookup operation, the validity and legality of the two key input signals—the area status signal and the travel direction signal—must be verified. This step is a preliminary safety judgment in the control flow, designed to prevent illegal signal combinations caused by sensor malfunctions, signal interference, or relay misoperation from entering the table lookup logic.

[0059] The verification includes: confirming whether the area status signal is a valid value (i.e., it corresponds only to the first or second area), whether the walking direction signal is a valid value (i.e., it corresponds only to forward or backward), and whether both are simultaneously at a valid level, excluding cases of signal loss or floating. This verification is automatically performed by the central control unit each time a signal change is triggered, without relying on external intervention.

[0060] The position status mapping table pre-sets only four valid input combinations: (First area, forward), (First area, backward), (Second area, forward), and (Second area, backward). If the verification finds that the combination of the current area status signal and the walking direction signal does not belong to one of the above four, for example, the area status signal is abnormally high impedance, the walking direction signal indicates both forward and backward, or the area status signal is invalid due to a bistable relay failure, then the central control unit determines that the combination is a control logic conflict. This determination indicates that the system is in an unexpected operating state, which may endanger cable safety or equipment stability. Therefore, the normal control process must be stopped immediately, and the system must switch to fault protection mode.

[0061] Once a control logic conflict is detected, the central control unit immediately stops generating and outputting any rotation direction control commands and operating mode commands. This means that the variable frequency drive unit will not receive any valid signals for controlling the direction or operating status of the drum motor, thereby avoiding incorrect motor drive under uncertain operating conditions and preventing power cable breakage, insulation breakdown, or mechanical damage to the drum due to reverse cable winding or uncontrolled tension.

[0062] While prohibiting the output of control commands, the central control unit activates a dedicated fault-locking relay. The normally closed contact of this relay is connected in series in the enable circuit of the drum motor. When the relay is activated (coil energized), its contacts open, physically cutting off the power supply enable signal from the frequency converter drive unit to the drum motor. Even if residual commands or false triggering exist within the frequency converter drive unit, the motor cannot start or continue running, thus achieving hardware-level safety interlocking protection. This fault-locking relay has a self-locking function; unless manually reset or the system restarts and passes a self-test, it remains open, ensuring that the equipment cannot resume operation until the fault is resolved.

[0063] The central control unit activates the fault-locking relay and simultaneously sends standardized alarm information to the human-machine interface. The alarm information clearly indicates the type of control logic conflict fault and may include the area status signal value, travel direction signal value, and timestamp at the time of the fault, facilitating rapid identification of the root cause by maintenance personnel (such as proximity switch failure, bistable relay jamming, or PLC input module failure). The alarm information is presented on the operator station in the form of audible and visual prompts or text pop-ups and remains displayed until the fault is cleared.

[0064] Specifically, the region state holding unit includes a first bistable relay and a second bistable relay.

[0065] The set coil circuit of the first bistable relay has a normally closed contact of the second bistable relay connected in series.

[0066] The normally closed contact of the first bistable relay is connected in series in the set coil circuit of the second bistable relay.

[0067] The first bistable relay and the second bistable relay form a bidirectional electrical interlock structure, ensuring that the other relay can only be set when one relay is in the reset state.

[0068] Furthermore, the area state holding unit is a functional module used to latch and stably output electrical signals characterizing the spatial area where the stacker-reclaimer is located. Its hardware configuration consists of only two independent bistable relays: a first bistable relay and a second bistable relay.

[0069] Both the first and second bistable relays are electromagnetic relays with memory function, equipped with a set coil, a reset coil, normally open contacts, and normally closed contacts, capable of maintaining their current state (set or reset) without continuous excitation. The state of the first bistable relay indicates that the stacker-reclaimer is located in the first area, and the state of the second bistable relay indicates that the stacker-reclaimer is located in the second area. The two relays are opposite representations of the area states, jointly covering the entire travel area without overlap.

[0070] The setting action of the first bistable relay is achieved by energizing its set coil, and a set of normally closed contacts of the second bistable relay is connected in series in the power supply circuit of the set coil. When the second bistable relay is in the set state, its normally closed contacts are open, preventing the set coil circuit of the first bistable relay from forming a closed path. Even with a set trigger signal input, the first bistable relay cannot be set. Only when the second bistable relay is in the reset state, its normally closed contacts close, the set coil circuit is connected, and the first bistable relay has the electrical conditions to be set. This design prevents the possibility of both relays being set simultaneously at the hardware level.

[0071] Similarly, a set of normally closed contacts of the first bistable relay is connected in series in the set coil circuit of the second bistable relay. When the first bistable relay is in the set state, its normally closed contacts are open, cutting off the set coil circuit of the second bistable relay and preventing it from responding to the set command; only when the first bistable relay is in the reset state, its normally closed contacts are closed, and the set coil circuit of the second bistable relay is turned on, thus allowing it to be set.

[0072] By connecting the normally closed contacts of the first and second bistable relays, a purely hardware-implemented bidirectional electrical interlocking structure is formed. The logical effect of this structure is that at any given time, at most one of the two relays can be in the set state, while the other must be in the reset state.

[0073] When the stacker-reclaimer is in the first zone, the first bistable relay is set, its normally closed contact opens, and the setting capability of the second bistable relay is locked.

[0074] When the stacker-reclaimer crosses the cable exit point and enters the second zone, the proximity switch triggers a set signal. However, since the first bistable relay is still in the set state, the second bistable relay cannot be set immediately. It must first be reset via reset logic (e.g., using a proximity switch pulse in conjunction with a direction signal). Only after its normally closed contact closes can the second bistable relay be set. The reverse is also true. This interlocking mechanism fundamentally eliminates the possibility of zone status signal conflicts, ensuring the logical uniqueness of subsequent lookup control and system security.

[0075] Specifically, the central control unit is a programmable logic controller, whose digital output port is connected to the forward and reverse start terminals of the frequency converter via an opto-isolation circuit, and whose analog output port or communication interface is connected to the frequency setting terminal of the frequency converter.

[0076] The operating mode command is transmitted to the frequency converter through the communication interface. The frequency converter, based on the actual operating status of the motor, automatically enters the corresponding motoring state or generator braking state.

[0077] Furthermore, the central control unit is the control component that performs position status determination, table lookup operations, instruction generation, and fault handling. It is housed in an industrial-grade programmable logic controller (PLC). This PLC has digital input modules, digital output modules, analog output modules, and a standard communication interface. Its internal program embeds a position status mapping table, signal verification logic, fault handling procedures, and output mapping rules. It can respond to changes in external signals in real time and output precise control commands, meeting the reliability, real-time performance, and anti-interference requirements of the stacker-reclaimer's power drum control.

[0078] The programmable logic controller (PLC) has two independent digital output ports for outputting forward and reverse control commands, respectively. The output signal from each digital output port first passes through an opto-isolation circuit, composed of light-emitting diodes (LEDs) and phototransistors, to achieve electrical isolation between the control side (low-voltage) and the drive side (high-voltage). This effectively blocks high voltage, high current, or electromagnetic interference from the inverter side from entering the PLC, improving system safety and stability. The opto-isolated output signals are then connected to the inverter's forward and reverse start terminals, which are dedicated digital input interfaces within the inverter for controlling the motor's rotation direction.

[0079] When the forward start terminal receives a valid level (such as 24VDC), the frequency converter drives the drum motor to rotate in the forward direction; when the reverse start terminal receives a valid level, the frequency converter drives the drum motor to rotate in the reverse direction; the two are interlocked and cannot be valid at the same time to prevent directional conflict.

[0080] The programmable logic controller (PLC) provides the frequency setting signal to the frequency converter in one of two optional ways: one is to use its analog output port to output a standard analog signal of 0-1V or 4-20mA and connect it directly to the frequency setting terminal of the frequency converter; the other is to send the frequency value to the frequency converter through its communication interface (such as RS485) using a digital communication protocol.

[0081] The frequency setting terminal is the input interface used by the frequency converter to receive the target operating frequency command. Based on this, the frequency converter adjusts the frequency of the AC power supply it outputs to the drum motor, thereby controlling the motor speed. This frequency value is dynamically calculated based on the trolley's traveling speed to ensure that the drum's linear speed matches the trolley's traveling speed, reducing cable stress.

[0082] The operating mode command is a control signal generated by the central control unit after looking up a table. It indicates the energy conversion mode the motor should be in, specifying either the motoring state or the regenerative braking state. This command is not output through digital or analog ports; instead, it is sent to the frequency converter in data frames via the programmable logic controller (PLC) through its communication interface. The communication protocol predefines the operating mode parameter address. The PLC writes the corresponding status code to this address, and the frequency converter parses it and executes the corresponding control strategy. Using communication to transmit the operating mode command avoids additional hardwiring, improving system integration and flexibility.

[0083] After receiving the operating mode command, the frequency converter does not simply switch the output polarity, but makes a comprehensive judgment based on the actual operating status of the motor (including internal feedback parameters such as speed, torque direction, and DC bus voltage) and automatically configures its internal control algorithm to enter the specified operating mode.

[0084] When the operating mode command is in electric state, the frequency converter drives the motor in voltage source inversion mode, absorbs electrical energy from the grid, and outputs positive electromagnetic torque to make the drum actively reel in the cable.

[0085] When the operating mode command is regenerative braking state, the frequency converter detects that the motor rotor speed is higher than the synchronous speed (i.e., driven by the load) and automatically activates the regenerative braking or energy consumption braking function. The regenerative electrical energy generated by the motor is consumed by the braking resistor through the braking unit or fed back to the DC bus, thereby generating an electromagnetic braking torque opposite to the direction of rotation, so that the drum maintains constant damping tension during the cable release process.

[0086] Specifically, in the generator braking state, the frequency conversion drive unit monitors the DC bus voltage and adjusts the energy consumption power of the braking unit according to the voltage change in order to maintain a constant damping tension of the cable on the drum.

[0087] Furthermore, when the variable frequency drive unit enters the regenerative braking state according to the operating mode command, it has the function of real-time detection of the DC bus voltage. The DC bus voltage is the potential level of the DC link inside the variable frequency drive unit. During the regenerative braking process, the drum motor is driven to rotate by the stacker-reclaimer, generating regenerative electrical energy. This electrical energy is fed back to the DC bus, causing the DC bus voltage to change. The variable frequency drive unit continuously obtains the current value of the DC bus voltage through its built-in voltage detection mechanism as the basis for subsequent adjustment actions.

[0088] The variable frequency drive unit compares the monitored DC bus voltage with its normal operating range. If the voltage deviates from the normal range, it automatically adjusts the power consumption of the braking unit. This adjustment is performed autonomously by the variable frequency drive unit without external command intervention. The braking unit is a component or external functional module of the variable frequency drive unit, and its function is to consume regenerative energy. By changing its power consumption, the rate of regenerative energy discharge can be controlled, thereby affecting the stability of the DC bus voltage. The adjustment process aims to maintain the safe operation of the system, ensuring that the DC bus voltage does not rise abnormally due to energy accumulation.

[0089] By adjusting the power consumption of the braking unit as described above, the frequency converter drive unit maintains a stable braking effect generated by the drum in the generator braking state. This braking effect is transmitted to the drum via the transmission mechanism, manifesting as damping tension on the power cable. Without this adjustment mechanism, the tension on the cable would fluctuate when the stacker-reclaimer's travel speed changes. This invention, by monitoring the DC bus voltage and dynamically adjusting the power consumption, ensures that the damping tension applied by the drum to the cable remains at a set level, achieving constant damping tension. This prevents insulation deformation or breakdown due to excessive tension, and also prevents cable slack and accumulation due to insufficient tension, thus ensuring the safe deployment and long-term reliable operation of the power cable.

[0090] Specifically, a position detection-based stacker-reclaimer power drum control system also includes a tension anomaly diagnosis module, which includes a current sampling circuit, a torque estimation unit, and a voltage fluctuation analysis unit.

[0091] The current sampling circuit is used to collect the three-phase current of the drum motor and calculate the effective value and rate of change.

[0092] The torque estimation unit is used to perform trend analysis based on the torque command value output by the frequency converter.

[0093] The voltage fluctuation analysis unit is used to monitor the instantaneous fluctuation amplitude of the DC bus voltage.

[0094] When two or more of the four parameters—current RMS value, current change rate, torque command trend, and DC bus voltage fluctuation amplitude—exceed their respective safety threshold ranges within multiple consecutive control cycles, the system determines that the cable tension is abnormal and executes the drum shutdown and trolley deceleration linkage protection.

[0095] Furthermore, the tension anomaly diagnosis module assesses in real time whether the tension on the power cable is in an abnormal state, and its output directly triggers the linkage protection action.

[0096] The tension anomaly diagnosis module consists of three sub-units: a current sampling circuit, a torque estimation unit, and a voltage fluctuation analysis unit. These three sub-units collect or analyze operating parameters related to cable tension from different physical dimensions. They work independently but share data, jointly providing multi-source criteria for tension anomaly judgment, thus improving the reliability and anti-interference capability of the diagnosis.

[0097] The current sampling circuit is connected to the power supply circuit of the drum motor, acquiring the three-phase current signal flowing through the drum motor in real time. Based on the acquired three-phase current, the circuit calculates the effective value (i.e., root mean square value) of the current and the rate of change of the effective value of the current in the time domain. When the cable tension increases abnormally, the load torque of the drum motor changes abruptly, causing the effective value of the three-phase current to increase significantly or its rate of change to increase sharply; conversely, if the cable is slack or slipping, the current may drop sharply. Therefore, the effective value of the current and its rate of change are electrical indicators reflecting the cable tension state.

[0098] The torque estimation unit receives torque command values ​​from the frequency converter. These command values ​​are internal control quantities output by the frequency converter based on the current operating mode and frequency settings, representing the expected electromagnetic torque applied to the drum motor. Instead of recalculating the torque, the torque estimation unit performs trend analysis on the numerical sequence of the torque command values ​​over multiple consecutive control cycles to determine if they exhibit abnormal trends such as continuous increases, sudden changes, or oscillations. Since cable tension directly reflects the required load torque output by the motor, abnormal trends in the torque command values ​​can indirectly indicate abnormal tension.

[0099] The voltage fluctuation analysis unit is connected to the DC bus of the frequency converter drive unit, monitoring the instantaneous value of the DC bus voltage in real time and calculating its fluctuation amplitude within a short time window, i.e., the difference or standard deviation between the maximum and minimum voltage values. During regenerative braking, a sudden change in cable tension (such as jamming or sudden release) will cause a drastic change in the feedback energy, resulting in a large instantaneous fluctuation in the DC bus voltage. Therefore, the instantaneous fluctuation amplitude of the DC bus voltage is a basis for judging tension stability.

[0100] A corresponding safety threshold range is set for the effective value of current, rate of change of current, torque command trend, and DC bus voltage fluctuation amplitude. Each parameter is detected and compared with its own threshold in each control cycle. An abnormal cable tension is only determined when any two or more parameters simultaneously exceed their respective safety threshold ranges for multiple consecutive control cycles (e.g., 3 or 5 consecutive cycles, the specific number determined by the system design). This multi-parameter and continuous-cycle criterion effectively avoids false alarms caused by single interference or measurement noise, improving the accuracy and robustness of diagnosis.

[0101] Once it is determined that the cable tension is abnormal, the central control unit immediately executes interlock protection measures: on the one hand, it sends a shutdown command to the variable frequency drive unit to stop the drum motor and achieve drum shutdown; on the other hand, it sends a deceleration command to the traveling drive system of the stacker-reclaimer to gradually reduce the traveling speed of the cart until it stops. This interlock protection mechanism cuts off the possibility of continuous tension increase at the source, preventing the power cable from suffering from insulation breakdown, breakage or permanent deformation due to overload, and ensuring the safety of equipment and personnel.

[0102] The present invention will be further described in detail below in combination with specific hardware connections and control logics. This embodiment provides a complete implementation scheme for a power drum control system of a stacker-reclaimer based on position detection.

[0103] 1. System hardware architecture and power supply configuration.

[0104] This system adopts a hierarchical power supply scheme. The control circuit uses a dual-power system of DC24V and AC220V. Among them, as Figure 1 、 Figure 2 shown, the DC24V power busbars numbered 0511 and 0512 provide working voltage for all relay coils; as Figure 3 shown, the AC220V power busbars numbered 0523 and 0506 provide working voltage for high-power control components.

[0105] The power system adopts three-phase AC power supply. As Figure 4 shown, the three-phase power supplies L01, L02, and L03 are connected to the system through the main power circuit breaker numbered 20F, and then connected to the power input terminal of the variable frequency drive VVVF through the main contacts of the main contactor KM.

[0106] 2. Specific implementation of the position detection and area status holding unit.

[0107] The position detection system is jointly realized by proximity switches and rotary encoders. As Figure 1 shown, the proximity switch 1SF6 installed at the cable outlet is responsible for detecting whether the stacker-reclaimer passes through this reference position. When the stacker-reclaimer passes by, the normally open contact of 1SF6 closes, driving the coil of the intermediate relay 1ZJ3 to be energized.

[0108] The core of the area status holding unit is an interlock structure composed of two bistable relays ZJ1 and ZJ2. As Figure 1 、 Figure 2 shown, the specific connection method is: in the set coil circuit of the first bistable relay ZJ1, the normally closed contact of the second bistable relay ZJ2 is connected in series; in the set coil circuit of the second bistable relay ZJ2, the normally closed contact of the first bistable relay ZJ1 is connected in series. This hardware interlock design ensures at the electrical level that the two relays cannot be in the set state simultaneously.

[0109] like Figure 1 As shown, the setting of the first bistable relay ZJ1 is achieved through three independent paths: The first path: When the forward stop limit switch 1SF1 is triggered, its normally closed contact opens, causing the coil of the forward limit associated relay 1ZJ1 to lose power. The normally closed contact of 1ZJ1 then returns to the closed state, connecting the ZJ1 set coil circuit.

[0110] The second path: When the encoder travel value is greater than 65.8 and less than 131.6, the normally open contact of the output relay 1PC4 closes, directly connecting the ZJ1 set coil circuit.

[0111] The third path: Manually connect the ZJ1 set coil circuit by pressing the set button SA1.

[0112] like Figure 2 As shown, the setting of the second bistable relay ZJ2 is also achieved through three independent paths: The first path: When the reverse stop limit switch 1SF3 is triggered, its normally closed contact opens, causing the coil of the reverse limit associated relay 1ZJ2 to lose power. The normally closed contact of 1ZJ2 then returns to the closed state, connecting the ZJ2 set coil circuit.

[0113] The second path: When the encoder travel value is less than 65.8 and greater than 0, the normally open contact of the output relay 1PC5 closes, directly connecting the ZJ2 set coil circuit.

[0114] The third path: Manually connect the ZJ2 set coil circuit by pressing the set button SA3.

[0115] The region state is reset in the following way: like Figure 1 As shown, when the stacker-reclaimer reverses past the cable lead-out point, proximity switch 1SF6 is activated, intermediate relay 1ZJ3 is energized, and its normally open contact closes. At this time, if the normally open contact of the trolley reversing control relay 1PC2 is in the closed state, the ZJ1 reset coil circuit is connected.

[0116] like Figure 2 As shown, when the stacker-reclaimer moves forward past the cable lead-out point, it also operates through 1SF6 and 1ZJ3. At this time, if the normally open contact of the trolley forward control relay 1PC1 is in the closed state, the ZJ2 reset coil circuit is connected.

[0117] The system also includes manual reset buttons SA2 and SA4, which are used to manually reset ZJ1 and ZJ2, respectively.

[0118] 3. Specific implementation of the walking direction recognition unit.

[0119] The direction of travel is identified through the trolley forward control relay 1PC1 and the trolley reverse control relay 1PC2. For example... Figure 1 , Figure 2 As shown, when the stacker-reclaimer moves forward, coil 1PC1 is energized, its normally open contact closes, and it outputs a forward direction signal; when the stacker-reclaimer moves backward, coil 1PC2 is energized, its normally open contact closes, and it outputs a backward direction signal.

[0120] The travel limit protection is achieved by connecting a limit switch in series in the aforementioned relay coil circuit: such as Figure 1 As shown, the normally closed contact of the forward limit switch 1SF1 is connected in series in the coil circuit of the forward control relay 1PC1; the normally closed contact of the backward limit switch 1SF3 is connected in series in the coil circuit of the backward control relay 1PC2. When the stacker-reclaimer moves to the corresponding limit position, the limit switch is activated, cutting off the power supply to the control relay coil in the corresponding direction.

[0121] 4. Specific implementation of the central control unit and location calculation.

[0122] The central control unit is implemented using a programmable logic controller (PLC), which is responsible for position calculation, logical judgment, and control command generation.

[0123] The position detection element uses a rotary encoder, which outputs two-phase pulse signals, A and B. For example... Figure 5 As shown, the programmable logic controller receives these pulse signals through a high-speed counting module and uses its internal program to calculate the walking distance.

[0124] The walking distance calculation is implemented through two addition function blocks: like Figure 5 As shown, the forward displacement calculation function block is activated when both the forward walking signal and the forward walking encoder A signal are valid. It adds the value in the current walking code value storage unit %MW214 to the step size value 1.0, and stores the result back into %MW214.

[0125] like Figure 5 As shown, the backward displacement calculation function block is activated when both the walking backward signal and the walking encoder B signal are valid. It adds the value in %MW214 to the step size value -1.0 and stores the result back in %MW214.

[0126] like Figure 5 As shown, the walking distance conversion is achieved through the real number division function block, which divides the walking code value %MW214 by the coefficient 5059.0 to obtain the actual walking distance value, which is stored in %MW104.

[0127] like Figure 5 As shown, region determination is implemented using four real number comparators: The first zone determination is achieved through the coordinated operation of two comparators: the first comparator checks if the travel distance %MW104 is less than 65.8, and the second comparator checks if the travel distance %MW104 is greater than 0.0. When both conditions are met simultaneously, the stacker-reclaimer is determined to be located in the first zone.

[0128] The second zone determination is achieved through the coordinated operation of two additional comparators: the first comparator checks if the travel distance %MW104 is less than 131.6, and the second comparator checks if the travel distance %MW104 is greater than 65.8. When both conditions are met simultaneously, the stacker-reclaimer is determined to be located in the second zone.

[0129] 5. Specific implementation of variable frequency drive and control.

[0130] The core of a variable frequency drive unit is the frequency converter (VVVF). For example... Figure 4 As shown, its power circuit connection is as follows: the power input terminal is connected to a three-phase power supply, and the output terminals U, V, and W are connected to the three-phase windings of the drum motor M.

[0131] The control loop connection specifically includes: like Figure 4 As shown, the forward rotation control is connected to the forward rotation start terminal of the frequency converter through the normally open contact of the forward rotation control relay ZJ5.

[0132] like Figure 4 As shown, the reverse control is connected to the reverse start terminal of the frequency converter through the normally open contact of the reverse control relay ZJ4.

[0133] like Figure 4 As shown, the speed control is connected to the multi-speed control terminal of the frequency converter through the contacts of the high-speed control relay ZJ6.

[0134] like Figure 4 As shown, the system reset is achieved by connecting the contacts of the inverter remote control reset relay PC4 to the inverter's reset control terminal.

[0135] The working process of the braking control system is as follows: Figure 3 As shown, when the coil of the forward control relay ZJ5 or the reverse control relay ZJ4 is energized, its auxiliary normally open contact closes, energizing the coil of the time relay SJ; the delayed closing contact of SJ closes after a set time, connecting the coil of the brake control relay ZJ, driving the brake to release, and ensuring that the drum motor starts without braking resistance.

[0136] The main power supply control system's workflow is as follows: Figure 3 As shown, when either the ZJ5 or ZJ4 coil is energized, the main contactor KM coil is energized, and the main contacts of KM close, providing three-phase power to the frequency converter.

[0137] 6. Specific implementation of the security protection system.

[0138] The fault protection system is implemented through the fault-locking relay KA1. For example... Figure 3 As shown, when the programmable logic controller detects a control logic conflict, it outputs a signal to energize the KA1 coil, causing the normally closed contact of KA1 to open and disconnecting the coil circuits of the forward control relay ZJ5 and the reverse control relay ZJ4.

[0139] Overload protection is achieved through a thermal relay FR. For example... Figure 3 , Figure 4 As shown, the normally closed contact of FR is connected in series on the bus of the control circuit. When the current of the drum motor exceeds the safety threshold, FR will activate, its normally closed contact will open, and the entire control circuit will be cut off.

[0140] Braking timing control is achieved through a time relay SJ. For example... Figure 3 As shown, SJ ensures that the brake is released with a delay when the motor starts and that the brake is engaged with a delay when the motor stops, thus ensuring the smoothness of the control process.

[0141] 7. Specific implementation of system control procedures.

[0142] System power-on initialization process: If the trolley is at the forward stop limit, the first bistable relay ZJ1 is set by the action of limit switch 1SF1 and relay 1ZJ1, indicating that the stacker-reclaimer is in the second area.

[0143] If the trolley is at the reverse stop limit, the second bistable relay ZJ2 is set by the action of limit switch 1SF3 and relay 1ZJ2, indicating that the stacker-reclaimer is in the first area.

[0144] If the trolley is in the middle position, the corresponding bistable relay is set by output relay 1PC4 or 1PC5 based on the travel distance value calculated by the encoder.

[0145] Normal operation control process: The programmable logic controller continuously monitors the area status signal and the walking direction signal.

[0146] When a change in the combination of area state and walking direction is detected, the internally stored position state mapping table is invoked.

[0147] Output the corresponding control commands based on the table lookup results: When the stacker-reclaimer is in the first zone and its travel direction is forward, it outputs a forward rotation control signal, which energizes the coil of the forward rotation control relay ZJ5, and the drum performs the cable winding operation.

[0148] When the stacker-reclaimer is in the first zone and moving in the backward direction, it outputs a reverse control signal to energize the coil of the reverse control relay ZJ4, and the drum performs the cable unwinding operation.

[0149] When the stacker-reclaimer is in the second zone and its travel direction is forward, it outputs a reverse control signal to energize the coil of the reverse control relay ZJ4, and the drum performs the cable unwinding operation.

[0150] When the stacker-reclaimer is in the second zone and traveling in the backward direction, it outputs a forward rotation control signal, which energizes the coil of the forward rotation control relay ZJ5, and the drum performs the cable winding operation.

[0151] At the same time, the speed of the drum motor is dynamically adjusted according to the traveling speed of the trolley: When the trolley travels at low speed, the high-speed control relay ZJ6 coil is de-energized, and the frequency converter operates at the default low-speed frequency.

[0152] When the trolley travels at high speed, the coil of the high-speed control relay ZJ6 is energized, and a high-speed frequency setting command is output to the frequency converter.

[0153] During the cable laying operation, the drum motor is driven to rotate by the stacker-reclaimer. The frequency conversion drive unit automatically enters the generator braking state and consumes regenerative energy through the external braking unit to maintain the DC bus voltage stability, thereby achieving constant damping tension of the cable on the drum.

[0154] Troubleshooting process: When the programmable logic controller detects an illegal combination of area state and walking direction, it immediately activates the fault lockout relay KA1.

[0155] When the normally closed contact of KA1 opens, it cuts off the coil circuit of the forward control relay ZJ5 and the reverse control relay ZJ4, stopping the drum operation.

[0156] At the same time, detailed fault alarm information is output through the human-machine interface to guide maintenance personnel in troubleshooting.

[0157] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method of a power reel of a stacker-reclaimer based on position detection, comprising the following steps: setting a cable exit point on a travel path of the stacker-reclaimer, and dividing a travel area into a first area and a second area based on the cable exit point; detecting whether the stacker-reclaimer passes through the cable exit point by using a proximity switch installed near the cable exit point, and generating an area state signal representing a current area in combination with a bistable relay; obtaining a travel direction signal of forward or reverse movement of a trolley; taking the area state signal and the travel direction signal as input variables, calling a preset position state corresponding table, and generating a rotating direction control instruction and an operation mode instruction of a reel motor according to a control strategy associated with a combination of an area and a direction configured in the corresponding table; and dynamically adjusting an output frequency of a frequency converter of the reel motor based on a preset speed-frequency mapping relationship according to a trolley travel speed, and controlling a working state of the motor according to the operation mode instruction, so that the reel generates a torque matching a cable dragging direction through a magnetic coupling. 2.The control method of claim 1, wherein: the controlling of the working state of the motor according to the operation mode instruction comprises: controlling the motor to operate in an electric mode during a cable winding operation, and controlling the motor to operate in a generator braking mode during a cable unwinding operation; and the control strategy configured in the position state corresponding table is: determining that the cable unwinding operation is performed when the stacker-reclaimer is in the first area and the travel direction is forward; determining that the cable winding operation is performed when the stacker-reclaimer is in the first area and the travel direction is reverse; determining that the cable winding operation is performed when the stacker-reclaimer is in the second area and the travel direction is forward; and determining that the cable unwinding operation is performed when the stacker-reclaimer is in the second area and the travel direction is reverse. 3.The control method of claim 1, wherein: the position state corresponding table is stored in a non-volatile memory of a programmable logic controller in a software data structure form, and is used to establish a mapping relationship between a combination of an area state and a travel direction and a motor control action. 4.The control method of claim 3, wherein: the position state corresponding table is implemented in a two-dimensional array form, a row index corresponds to an area state code, a column index corresponds to a travel direction code, and an array element is a control word containing a rotating direction identifier and an operation mode identifier; when a combination of the area state signal and the travel direction signal changes, a table lookup operation is triggered, a query result is parsed into a rotating direction control instruction and an operation mode instruction, and the instructions are output to a reel motor frequency converter. Further comprising: before calling the position state corresponding table, checking the area state signal and the travel direction signal; if the combination is not defined in the table, determining that a control logic conflict occurs, prohibiting the output of the control instructions, activating a fault locking relay to cut off a motor enable circuit, and outputting alarm information through a human-machine interface. Further comprising: a position detection unit configured to detect whether the stacker-reclaimer passes through the cable exit point. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5. The method of claim 1, wherein, ​ ​ ​ 6. A position detection based control system for a power drum of a stacker reclaimer, characterized in that, ​ ​ A region state holding unit is configured to latch a region state signal representing that the stacker-reclaimer is located in the first region or the second region according to the output of the position detection unit; A direction identification unit is configured to acquire a walking direction signal of the stacker-reclaimer; A central control unit is connected with the region state holding unit and the direction identification unit, and is configured to call a position state corresponding table, generate a rotating direction control instruction and an operation mode instruction of the drum motor according to the combination of the region state signal and the walking direction signal; A variable frequency driving unit is connected with the central control unit, and is configured to adjust the steering of the drum motor according to the rotating direction control instruction, dynamically set the operation frequency of the motor according to the walking speed of the cart, and control the working state of the motor according to the operation mode instruction.

7. The stacker-reclaimer power drum control system based on position detection according to claim 6, wherein: The region state holding unit comprises a first bistable relay and a second bistable relay; The set coil loop of the first bistable relay is connected with the normally closed contact of the second bistable relay in series; The set coil loop of the second bistable relay is connected with the normally closed contact of the first bistable relay in series; The first bistable relay and the second bistable relay form a bidirectional electrical interlocking structure, so that only when one side relay is in the reset state, the other side relay can be set.

8. The stacker-reclaimer power drum control system based on position detection according to claim 6, wherein: The central control unit is a programmable logic controller, the digital output port of which is connected to the forward rotation and reverse rotation starting end of the frequency converter through an optical isolation circuit, and the analog output port or the communication interface of which is connected to the frequency setting end of the frequency converter; The operation mode instruction is transmitted to the frequency converter through the communication interface, and the frequency converter automatically enters the corresponding motor state or the power generation braking state in combination with the actual operation state of the motor.

9. The stacker-reclaimer power drum control system based on position detection according to claim 6, wherein: In the power generation braking state, the variable frequency driving unit monitors the DC bus voltage, and adjusts the energy consumption power of the braking unit according to the voltage change, so as to maintain the constant damping tension of the drum on the cable.

10. A position detection based control system for a power drum of a stacker reclaimer as claimed in claim 6 wherein, Further comprising a tension abnormality diagnosis module, the tension abnormality diagnosis module comprising a current sampling circuit, a torque estimation unit and a voltage fluctuation analysis unit; The current sampling circuit is configured to acquire the three-phase current of the drum motor and calculate the effective value and the change rate; The torque estimation unit is configured to perform trend analysis according to the torque instruction value output by the frequency converter; The voltage fluctuation analysis unit is configured to monitor the instantaneous fluctuation amplitude of the DC bus voltage; When two or more of the four parameters of the current effective value, the current change rate, the torque instruction trend and the DC bus voltage fluctuation amplitude exceed the respective safety threshold range in continuous multiple control periods, the system determines that the cable tension is abnormal, and executes the drum shutdown and cart deceleration linkage protection.

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