Adaptive Paver Screw Electric Heating Control Method and System

Abstract

The adaptive paver screed electric heating control method and system provided in this application specifically relate to the field of electrical control technology for construction machinery. This method uses a current monitoring unit to acquire the current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time. The logic control unit calculates the sum of the currents of each single phase based on this, compares it with preset overload current values ​​and preset protection current values ​​to perform a current state determination, and controls the contactor to engage or output an alarm signal or shut down the system according to the determination result. Simultaneously, for each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase and compared with a preset current difference value. When the current difference is greater than the preset value, a fault alarm signal is output and the corresponding contactor is disconnected. This method can avoid the risk of generator overload due to excessive heating power when the paver is adapted to multiple types of screeds, and achieve rapid location of heating strip open circuit faults.

Description

Technical Field

[0001] This invention relates to the field of electrical control technology for construction machinery, and more specifically, to an adaptive electric heating control method and system for the screed of a paver. Background Technology

[0002] As a core piece of equipment in high-grade highway construction, asphalt pavers require screeds that can adapt to different types (telescopic / mechanical / end-telescopic) and widths (6-12 meters). With the increasing complexity of municipal engineering projects, frequent screed replacements by users lead to severe load fluctuations in the electric heating control system: the generator's rated power (e.g., 32kW) is mismatched with the total power of the screed's heating elements (up to 40kVA), easily causing generator overload and burnout. Simultaneously, frequent heating element open-circuit faults make it difficult to perform segment-by-segment three-phase current balance checks using traditional manual diagnostics, which is time-consuming and prone to misjudgment, severely impacting construction efficiency and equipment safety.

[0003] Current solutions mainly focus on two categories:

[0004] 1. Leakage protection (such as patent CN109235203B): The fault section is located by leakage detection, but it does not involve current monitoring and generator overload protection;

[0005] 2. Power enhancement (e.g., patent CN118621659A): Heating efficiency is improved by adjusting the generator voltage, but it cannot dynamically adapt to the power requirements of different ironing boards and still relies on fixed hardware configuration.

[0006] Neither of these two solutions addresses the core challenge: how to monitor the current in real time and dynamically adjust the heating strategy to balance generator safety with the power requirements of different ironing plates.

[0007] In summary, the technical problem of how to solve the risk of generator overload caused by excessive heating power when pavers are adapted to multiple types of screeds, and at the same time achieve rapid location of heating bar open circuit faults, is an urgent problem to be solved. Summary of the Invention

[0008] The main objective of this invention is to provide an adaptive paver screed electric heating control method and system, which at least solves the risk of generator overload caused by excessive heating power when the paver is adapted to multiple types of screeds, and at the same time realizes the technical problem of rapid location of heating strip open circuit faults, thereby avoiding the risk of generator overload caused by excessive heating power when the paver is adapted to multiple types of screeds, and at the same time realizing the rapid location of heating strip open circuit faults.

[0009] To achieve the above objectives, the present invention provides an adaptive paver screed electric heating control method and system.

[0010] In a first aspect, the present invention provides an adaptive paver screed electric heating control method, the method comprising:

[0011] The current monitoring unit acquires the phase current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time.

[0012] In the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with the preset overload current value and the preset protection current value to perform current state determination.

[0013] When the sum of all the single-phase currents is less than the preset overload current value, control all contactors to engage to execute the full-power heating mode.

[0014] When the sum of any of the single-phase currents is greater than the preset overload current value and less than the preset protection current value, zoned alternating heating control is executed according to the cumulative timing result, wherein the cumulative timing result is used to indicate the duration of the state where the sum of any of the single-phase currents is greater than the preset overload current value and less than the preset protection current value;

[0015] When the sum of any of the single-phase currents exceeds the preset protection current value, an overload alarm signal is output and the electric heating control system is shut down.

[0016] For each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase, and the current difference is compared with a preset current difference value; when the current difference is greater than the preset current difference value, the fault alarm signal corresponding to the circuit breaker is output and the contactor corresponding to the circuit breaker is disconnected.

[0017] Specifically, the real-time acquisition of the phase current values ​​at the upper terminals of multiple circuit breakers in the electric heating control system via the current monitoring unit includes:

[0018] The instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker are collected by current transformers;

[0019] The instantaneous current value is filtered to obtain the steady-state current value, which is used as the current value of each phase.

[0020] Specifically, in the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with a preset overload current value and a preset protection current value to perform a current state determination, including:

[0021] Calculate the sum of the currents in phase U, phase V, and phase W on the multiple circuit breakers respectively to obtain the sum of the currents in phase U, phase V, and phase W.

[0022] The sum of the U-phase current, the sum of the V-phase current, and the sum of the W-phase current are compared with the preset overload current value and the preset protection current value, respectively.

[0023] A current status identifier is generated based on the comparison results. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

[0024] Specifically, the step of controlling all contactors to engage to execute full-power heating mode when the sum of all the single-phase currents is less than the preset overload current value includes:

[0025] When the current status indicator is normal, a closing command is sent to all contactors;

[0026] Monitor the contactor feedback signal, and once all contactors confirm engagement, maintain full-power heating until the temperature reaches the preset value.

[0027] Specifically, when the sum of any of the single-phase currents is greater than the preset overload current value and less than the preset protection current value, the step of executing zoned alternating heating control based on the cumulative timing result includes:

[0028] When the current status indicator is an overload indicator, the overload duration accumulation timer is started.

[0029] If the cumulative duration is less than the preset duration threshold, control all contactors to engage;

[0030] If the cumulative duration is greater than or equal to the preset duration threshold, the contactor will be divided into three groups for cyclic execution:

[0031] Group 1: Controls contactors KM1, KM2, and KM4 to engage, and KM3 and KM5 to disengage;

[0032] Second group: Controls contactors KM1, KM3, and KM5 to engage, and KM2 and KM4 to disengage;

[0033] Group 3: Controls contactors KM2, KM3, KM4, and KM5 to engage, and KM1 to disengage;

[0034] The duration of each suction session is equal to the preset alternating heating time.

[0035] Specifically, the step of outputting an overload alarm signal and shutting down the electric heating control system when the sum of any of the single-phase currents exceeds the preset protection current value includes:

[0036] When the current status indicator is a protection indicator, the audible and visual alarm is triggered to output the overload alarm signal;

[0037] Simultaneously send disconnect commands to all contactors and display the off status on the human-machine interface.

[0038] Specifically, for each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase, and the current difference is compared with a preset current difference value; when the current difference is greater than the preset current difference value, a fault alarm signal corresponding to the circuit breaker is output and the contactor corresponding to the circuit breaker is disconnected, including:

[0039] For the current circuit breaker, calculate the absolute values ​​of the current difference between phases UV, VW, and WU respectively;

[0040] When the absolute value of any of the current differences is greater than the preset current difference value, it is determined that the heating strip corresponding to the current circuit breaker has an open circuit fault.

[0041] Output a fault alarm signal containing the circuit breaker number corresponding to the current circuit breaker, and disconnect the contactor uniquely corresponding to the current circuit breaker. After disconnecting the contactor corresponding to the current circuit breaker, re-execute the current state determination.

[0042] In a second aspect, the present invention provides an adaptive paver screed electric heating control system, wherein the control system applies the control method described in the first aspect, and the control system includes:

[0043] The current monitoring unit is used to acquire the phase current values ​​of multiple circuit breakers in the electric heating control system in real time.

[0044] A logic control unit is connected to the current monitoring unit. The logic control unit is used to calculate the sum of the single-phase currents based on the current values ​​of each phase; and compare the sum of the single-phase currents with a preset overload current value and a preset protection current value to perform current status determination.

[0045] A control execution unit, connected to the logic control unit, is configured to: control all contactors to engage to execute full-power heating mode when the sum of all single-phase currents is less than the preset overload current value; execute zoned alternating heating control based on cumulative timing results when the sum of any single-phase current is greater than the preset overload current value but less than the preset protection current value, wherein the cumulative timing results are used to indicate the duration of the overload state; and output an overload alarm signal and shut down the electric heating control system when the sum of any single-phase current is greater than the preset protection current value.

[0046] The fault diagnosis unit is connected to the current monitoring unit and the logic control unit. The fault diagnosis unit is used to calculate the current difference between any two phases under the same circuit breaker based on the current values ​​of each phase for each circuit breaker; compare the current difference with a preset current difference value; and output the fault alarm signal corresponding to the circuit breaker and disconnect the contactor corresponding to the circuit breaker when the difference is greater than the preset current difference value.

[0047] Specifically, the current monitoring unit includes:

[0048] A current transformer array is used to collect the instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker;

[0049] A filtering module is connected to the current transformer array. The filtering module is used to filter the instantaneous current value and output the steady-state current value as the current value of each phase.

[0050] Specifically, the logic control unit includes:

[0051] The summation calculation module is used to calculate the sum of the currents of phase U, phase V and phase W on the multiple circuit breakers respectively, and output the sum of phase U current, the sum of phase V current and the sum of phase W current;

[0052] A comparison module is connected to the summation calculation module. The comparison module is used to compare the summation of U-phase current, V-phase current, and W-phase current with the preset overload current value and the preset protection current value, respectively.

[0053] A status identifier generation module is connected to the comparison module. The status identifier generation module is used to generate a current status identifier based on the comparison result. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

[0054] The adaptive paver screed electric heating control method and system provided in this application utilize a current monitoring unit to acquire the phase current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time. The logic control unit calculates the sum of the currents of each single phase based on this and compares it with preset overload current values ​​and preset protection current values ​​to determine the current status. If the sum of the currents of each single phase is less than the preset overload current value, all contactors are controlled to engage and enter full-power heating mode. If the sum of the currents of any single phase is between the preset overload and protection current values, zoned alternating heating control is executed based on the cumulative timing result. If it is greater than the preset protection current value, an overload alarm signal is output and the system is shut down. Furthermore, for each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated and compared with a preset current difference value. If the difference is too large, a fault alarm signal is output and the corresponding contactor is disconnected, effectively avoiding generator overload risks and achieving rapid location of heating strip open-circuit faults. Attached Figure Description

[0055] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0056] Figure 1 A flowchart illustrating the adaptive paver screed electric heating control method provided in this application;

[0057] Figure 2 A connection diagram of the adaptive paver screed electric heating control system provided in this application;

[0058] Figure 3 This is a schematic diagram of the structure of the adaptive paver screed electric heating control system provided in this application.

[0059] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0062] In this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0063] The adaptive paver screed electric heating control method and system provided in this application utilize a current monitoring unit to acquire the current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating system. The logic control unit calculates the sum of the currents of each single phase based on this value and compares it with preset overload and protection current values ​​to determine the current state. The contactor is controlled to operate according to different states, achieving full-power or zoned alternating heating modes. An alarm is output and the system is shut down when the limit is exceeded. Simultaneously, the current difference between any two phases under the same circuit breaker is calculated and compared with a preset value. If the difference exceeds the preset value, a fault alarm is output and the corresponding contactor is disconnected to avoid generator overload risks and quickly locate open-circuit faults in the heating strip.

[0064] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0065] Figure 1 This is a flowchart illustrating the adaptive paver screed electric heating control method provided in this application, as shown below. Figure 1 As shown, this embodiment provides an adaptive paver screed electric heating control method, which includes:

[0066] S101: The current monitoring unit acquires the phase current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time.

[0067] Specifically, the real-time acquisition of the phase current values ​​at the upper terminals of multiple circuit breakers in the electric heating control system via the current monitoring unit includes:

[0068] The instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker are collected by current transformers;

[0069] The instantaneous current value is filtered to obtain the steady-state current value, which is used as the current value of each phase.

[0070] The specific steps of implementation S101 include:

[0071] 1. Current transformer signal acquisition

[0072] 1.1 Hardware configuration: A through-type current transformer with an accuracy class of 0.5 is selected, and its primary side is connected in series to the U-phase, V-phase, and W-phase conductor circuits at the upper end of the circuit breaker.

[0073] 1.2 Signal Conversion: The secondary side of the current transformer outputs a 0-5A AC current signal, which is converted into a 0-1.25V voltage signal through a 250Ω precision sampling resistor.

[0074] 1.3 Data Acquisition: A 16-bit ADC (Analog-to-Digital Converter) was used to acquire voltage signals at a sampling rate of 1000 times per second, generating a sequence of instantaneous current values.

[0075]

[0076] in:

[0077] : Instantaneous value of U-phase current at the nth sampling point (unit: A);

[0078] : Instantaneous value of phase V current at the nth sampling point;

[0079] : Instantaneous value of phase W current at the nth sampling point;

[0080] N: Number of sampling points within each 200ms sampling period (N=200).

[0081] 2. Filtering process to generate steady-state current values

[0082] 2.1 Filtering Algorithm: An FIR low-pass filter (Hanning window, order M=50) designed using the window function method, with a cutoff frequency of... (Eliminate high-frequency noise caused by construction vibration).

[0083] 2.2 Difference Equations:

[0084]

[0085] In the formula:

[0086] : The steady-state current value at the k-th output point;

[0087] : FIR filter coefficients (generated using MATLAB fdatool);

[0088] : Instantaneous sequence of input current values.

[0089] 2.3 Execution steps:

[0090] Sequence of instantaneous current values ​​for each phase , , Apply the above FIR filtering independently;

[0091] Take the arithmetic mean of the filtered data within each 200ms window as the steady-state current value for that window:

[0092] ;

[0093] (V-phase and W-phase are calculated similarly) , ).

[0094] Output results: Steady-state current values ​​of phases U, V, and W at the upper terminals of each circuit breaker. , , , which serves as the phase current value for step S101.

[0095] This embodiment physically acquires the instantaneous three-phase current signals using current transformers, converts them into measurable voltage quantities via precision resistors, and then eliminates high-frequency noise interference from paver engine vibration using an FIR low-pass filter (cutoff frequency 10Hz, order 50) based on a Hanning window design. Finally, the arithmetic mean of the filtered data is calculated with a 200ms window, outputting a steady-state current value that accurately reflects the working state of the heating strip. This process solves the problem of false triggering caused by current signal fluctuations in the construction environment, providing stable and reliable data input for the subsequent current state determination step (S102). Furthermore, the linear phase characteristic of the FIR filter ensures the synchronization of the current signals in each phase, avoiding misjudgments due to three-phase imbalance.

[0096] S102: In the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with the preset overload current value and the preset protection current value to perform current state determination.

[0097] Specifically, in the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with a preset overload current value and a preset protection current value to perform a current state determination, including:

[0098] Calculate the sum of the currents in phase U, phase V, and phase W on the multiple circuit breakers respectively to obtain the sum of the currents in phase U, phase V, and phase W.

[0099] The sum of the U-phase current, the sum of the V-phase current, and the sum of the W-phase current are compared with the preset overload current value and the preset protection current value, respectively.

[0100] A current status identifier is generated based on the comparison results. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

[0101] The specific steps of implementation S102 include:

[0102] 1. Calculation of the sum of currents in each single phase

[0103] 1.1 Input data:

[0104] Obtain the steady-state current value at the upper end of each circuit breaker from S101. , , ), corresponding to the U / V / W three-phase data of 5 circuit breakers (F1-F5).

[0105] 1.2 Calculation process: The arithmetic summation algorithm is used to calculate the total current in each phase across all circuit breakers:

[0106]

[0107] in:

[0108] Total current in phase U (unit: A);

[0109] : The steady-state U-phase current value at the upper end of circuit breaker Fk (k=1,2,3,4,5);

[0110] V phase ( ), W phase ( The calculation is similar.

[0111] 2. Threshold comparison logic

[0112] 2.1 Preset parameters:

[0113] Preset overload current value (e.g., 53.4A);

[0114] Preset protection current value (e.g., 60A).

[0115] 2.2 Independent Comparison Rule (Three-Phase Parallel Execution):

[0116] like < →U-phase status = normal;

[0117] like ≤ < →U-phase state = overload;

[0118] like ≥ →U-phase status = protection.

[0119] Phase V and Phase W are judged independently using the same rules.

[0120] 3. Current status indicator generation

[0121] 3.1 Identification and coding rules (as shown in Table 1):

[0122] Table 1: Identifier Coding Rules Table

[0123] 3.2 Execution steps:

[0124] Generate a 3-bit binary code according to the rules in Table 1 above (e.g., U phase overload = 10, V phase normal = 01, W phase normal = 01 → combination code 100101).

[0125] The combined code is mapped to the identifier value (0x01 / 0x02 / 0x03) by looking up a table.

[0126] Output the identifier to the logic control unit register.

[0127] This embodiment calculates the sum of the three-phase currents U / V / W using an arithmetic accumulation algorithm. , , ), using independent threshold comparison rules (e.g. =53.4A, =60A) Each phase is classified into states (normal / overload / protection), and finally a unique current state identifier (0x01 / 0x02 / 0x03) is generated by looking up a table based on the three-phase state combination. This process transforms the raw current data of S101 into a machine-decision-friendly state signal, providing accurate input for subsequent hierarchical control (S103-S105), and the three-phase independent comparison mechanism ensures that the risk of generator three-phase imbalance is fully monitored.

[0128] S103: When the sum of all the single-phase currents is less than the preset overload current value, control all contactors to engage to execute the full-power heating mode.

[0129] Specifically, the step of controlling all contactors to engage to execute full-power heating mode when the sum of all the single-phase currents is less than the preset overload current value includes:

[0130] When the current status indicator is normal, a closing command is sent to all contactors;

[0131] Monitor the contactor feedback signal, and once all contactors confirm engagement, maintain full-power heating until the temperature reaches the preset value.

[0132] The specific steps in step S103 during implementation include:

[0133] 1. Contactor closing control

[0134] 1.1 Triggering conditions:

[0135] When the current status flag register in the logic control unit has a value of 0x01 (normal flag), the closing instruction sending process is executed.

[0136] 1.2 Command Transmission Protocol:

[0137] Using the Modbus RTU protocol, hexadecimal command frames are sent to the drivers of five contactors (KM1-KM5) via RS-485 bus.

[0138] 1.3 Execution Mechanism:

[0139] Send instruction frames sequentially and cyclically to the KM1-KM5 drivers;

[0140] Each transmission is spaced 50ms apart to avoid bus conflicts;

[0141] After receiving the instruction, the driver energizes the drive coil, causing the contactor to physically engage.

[0142] 2. Contactor status monitoring

[0143] 2.1 Feedback signal acquisition:

[0144] A 0.1Ω sampling resistor is connected in series at the output of each contactor to measure the load current value as a feedback signal;

[0145] If the feedback current value is consistently ≥5A (minimum operating current of the heating bar) for 200ms, the contactor is considered to be reliably engaged.

[0146] 2.2 Status Verification Logic:

[0147]

[0148] Where:

[0149] k: Contactor number (k=1,2,3,4,5);

[0150] : The engagement state of contactor k (1=engaged, 0=not engaged).

[0151] 2.3 Global State Determination: When all 5 contactor states satisfy:

[0152] .

[0153] 3. Full power maintenance control

[0154] 3.1 Temperature monitoring mechanism: Read the temperature sensor data of the ironing board and convert it into a digital signal through a 4-20mA transmitter. .

[0155] 3.2 Heating maintenance conditions:

[0156]

[0157] Where:

[0158] Preset heating temperature (e.g., 120℃);

[0159] : Current real-time temperature.

[0160] 3.3 Execution process:

[0161] Continuous temperature monitoring and contactor status ;

[0162] If any contactor is in an abnormal state ( If the value is 0, immediately resend the closing instruction;

[0163] when ≥ When the time comes, a disconnect command is sent to terminate heating.

[0164] This embodiment achieves contact closure control by sending standard command frames (function code 0x06) to the contactor driver via the Modbus RTU protocol. The reliability of the contactor's physical engagement is verified using a load current threshold determination method (≥5A for 200ms). Under closed-loop control with temperature sensor feedback (PT100 + 4-20mA transmitter), full-power heating is maintained until the preset temperature value is reached. This process solves the heating failure problem caused by contactor malfunction, ensuring that the ironing plate can be rapidly heated to the required construction temperature under normal current conditions, and the bus communication mechanism (RS-485+Modbus) guarantees control stability in industrial environments.

[0165] S104: When the sum of any of the single-phase currents is greater than the preset overload current value and less than the preset protection current value, zoned alternating heating control is executed based on the cumulative timing result.

[0166] Specifically, when the sum of any of the single-phase currents is greater than the preset overload current value and less than the preset protection current value, the step of executing zoned alternating heating control based on the cumulative timing result includes:

[0167] When the current status indicator is an overload indicator, the overload duration accumulation timer is started.

[0168] If the cumulative duration is less than the preset duration threshold, control all contactors to engage;

[0169] If the cumulative duration is greater than or equal to the preset duration threshold, the contactor will be divided into three groups for cyclic execution:

[0170] Group 1: Controls contactors KM1, KM2, and KM4 to engage, and KM3 and KM5 to disengage;

[0171] Second group: Controls contactors KM1, KM3, and KM5 to engage, and KM2 and KM4 to disengage;

[0172] Group 3: Controls contactors KM2, KM3, KM4, and KM5 to engage, and KM1 to disengage;

[0173] The duration of each suction session is equal to the preset alternating heating time.

[0174] The specific steps in step S104 during implementation include:

[0175] 1. Overload timing start and accumulation

[0176] 1.1 Triggering condition: When the logic control unit detects that the current status indicator register value is 0x02 (overload indicator), the timing process is started.

[0177] 1.2 Timing Mechanism:

[0178] The duration of overload is accumulated using a high-precision real-time clock (RTC) with a time resolution of 1 second.

[0179] Timing formula:

[0180]

[0181] In the formula:

[0182] Cumulative duration (unit: seconds);

[0183] : The time increment for each loop (fixed at 1 second).

[0184] 1.3 Storage Update:

[0185] Each loop will Write to non-volatile memory (such as EEPROM) to prevent data loss in the event of power failure.

[0186] 2. Full-power heating maintenance control

[0187] 2.1 Execution conditions: If < ( (This is a preset duration threshold, such as 3180 seconds = 53 minutes).

[0188] 2.2 Control Action: Send a closing command to all contactors (KM1-KM5) (same as the Modbus RTU protocol of S103) to maintain full power heating mode.

[0189] 3. Zoned alternating heating control

[0190] 3.1 Triggering condition: If ≥ .

[0191] 3.2 Grouping Loop Logic:

[0192] 3.2.1 First group control (duration = preset alternating heating time) (e.g., 300 seconds)

[0193] Contactors for engaging: KM1, KM2, KM4;

[0194] Disconnect contactors: KM3, KM5;

[0195] Example of a command frame (KM1 engaged): 01 06 00 01 FF 00 CRC.

[0196] 3.2.2 Second group control (duration = ):

[0197] Contactors for engaging: KM1, KM3, KM5;

[0198] Disconnect contactors: KM2, KM4.

[0199] 3.2.3 Third group control (duration = ):

[0200] Contactors for engaging: KM2, KM3, KM4, KM5;

[0201] Disconnect contactor: KM1.

[0202] 3.3 Loop Execution Mechanism:

[0203] Switching groups using a state machine model: Current group = (Current group mod 3) + 1.

[0204] After each group completes, reset the countdown timer. Switch to the next group.

[0205] 4. Continuous monitoring of overload conditions

[0206] 4.1 Real-time monitoring of current status indicators:

[0207] If the indicator changes from overload (0x02) to normal (0x01) or protection (0x03), the zone heating will be terminated immediately, and the process will jump to the corresponding procedure.

[0208] 4.2 Conditions for resetting accumulated time:

[0209] =0 when ≥43200 seconds (12 hours).

[0210] This embodiment uses a high-precision RTC to accumulate the overload duration. When the cumulative duration is less than a preset threshold (For the Stanford generator, overload is allowed for 53 minutes every 12 hours) Full-power heating is maintained, and zoned alternating heating control is activated when the threshold is exceeded. This control uses three sets of fixed contactor combinations (KM1 / KM2 / KM4, KM1 / KM3 / KM5, KM2 / KM3 / KM4 / KM5) to cycle through, with each set operating for a preset alternating heating time. (e.g., 300 seconds) Precise control is achieved, and group switching is realized through a state machine model. This solution dynamically allocates heating power when the generator is overloaded, avoiding generator overload damage, while ensuring that the screed is continuously heated, thus solving the problem of balancing system protection and heating efficiency when the paver is adapted to a high-power screed.

[0211] S105: When the sum of any of the single-phase currents exceeds the preset protection current value, an overload alarm signal is output and the electric heating control system is shut down.

[0212] Specifically, the step of outputting an overload alarm signal and shutting down the electric heating control system when the sum of any of the single-phase currents exceeds the preset protection current value includes:

[0213] When the current status indicator is a protection indicator, the audible and visual alarm is triggered to output the overload alarm signal;

[0214] Simultaneously send disconnect commands to all contactors and display the off status on the human-machine interface.

[0215] The specific steps in step S105 during implementation include:

[0216] 1. Audible and visual alarm triggering process

[0217] Alarm activation: When the current status indicator changes to the protection indicator (value 0x03), the audible and visual alarm is activated.

[0218] The light alarm is implemented by flashing a red LED indicator three times per second (on and off for 0.5 seconds each time), which is connected to the controller output terminal through a 220-ohm current-limiting resistor.

[0219] Sound alarm implementation: A piezoelectric buzzer emits a continuous 2000 Hz sound, driven by a pulse signal with a 70% duty cycle.

[0220] Alarm mode: Three short beeps every 60 seconds (0.5 seconds of sound + 0.5 seconds of silence) until manually reset.

[0221] 2. Contactor synchronous disconnection control

[0222] Power-off command transmission: A broadcast command (device address 00) is sent via RS-485 bus, with the command content "Disconnect all contactors".

[0223] Instruction format: A standardized Modbus RTU data frame containing register address 0001 and disconnect instruction code 0000.

[0224] Status verification: Monitor the contactor load current. If it does not drop below 0.5 Amperes within 500 milliseconds, automatically resend the command.

[0225] 3. Human-machine interface status display

[0226] Status update: Send Modbus TCP packets via Ethernet, containing the device address, status register address, and shutdown flag.

[0227] Visual cue: Display the 32-pixel-high red "Overload Shutdown" text (RGB color value #FF0000) in the lower right corner of the touchscreen.

[0228] Time recording: Synchronously displays real-time shutdown timestamps in the format of year-month-day hour:minute:second.

[0229] This embodiment provides immediate warning via an audible and visual alarm (3Hz flashing red light + 2kHz buzzer) when a system overload is detected. It also simultaneously cuts off power to all contactors via broadcast commands and updates the shutdown status and time displayed on the human-machine interface in real time. This solution achieves millisecond-level emergency power-off protection and establishes a complete fault tracing mechanism to ensure that operators can quickly locate the problem and reset the system.

[0230] S106: For each circuit breaker, calculate the current difference between any two phases under the same circuit breaker based on the current values ​​of each phase, and compare the current difference with a preset current difference value; when the current difference is greater than the preset current difference value, output the fault alarm signal corresponding to the circuit breaker and disconnect the contactor corresponding to the circuit breaker.

[0231] Specifically, for each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase, and the current difference is compared with a preset current difference value; when the current difference is greater than the preset current difference value, a fault alarm signal corresponding to the circuit breaker is output and the contactor corresponding to the circuit breaker is disconnected, including:

[0232] For the current circuit breaker, calculate the absolute values ​​of the current difference between phases UV, VW, and WU respectively;

[0233] When the absolute value of any of the current differences is greater than the preset current difference value, it is determined that the heating strip corresponding to the current circuit breaker has an open circuit fault.

[0234] Output a fault alarm signal containing the circuit breaker number corresponding to the current circuit breaker, and disconnect the contactor uniquely corresponding to the current circuit breaker. After disconnecting the contactor corresponding to the current circuit breaker, re-execute the current state determination.

[0235] The specific steps in step S106 during implementation include:

[0236] 1. Calculation of current difference under the same circuit breaker

[0237] 1.1 Input data:

[0238] Obtain the steady-state current value of the current circuit breaker (e.g., circuit breaker F1) from S101. (U phase), (V phase) (W phase).

[0239] 1.2 Difference Calculation:

[0240] Three sets of current differences were generated using the absolute value calculation method:

[0241]

[0242] In the formula:

[0243] : Absolute value of UV phase current difference (unit: A);

[0244] Other differences are defined similarly.

[0245] 2. Circuit break fault diagnosis

[0246] 2.1 Judgment conditions:

[0247] If any of the following conditions are met:

[0248] ;

[0249] The preset current difference (e.g., 5A) is equal to the rated current value of a single heating bar.

[0250] 2.2 Fault Location:

[0251] The circuit breaker is determined to have an open circuit fault in the heating element corresponding to it (e.g., circuit breaker F1 corresponds to the heating element of the basic middle plate).

[0252] 3. Fault alarm and contactor disconnection

[0253] 3.1 Alarm signal generation:

[0254] Alarm data frames are sent to the human-machine interface via RS-485 bus:

[0255] Device address | Function code 0x06 | Register address (no circuit breaker number) | Fault code 0xEE.

[0256] Example: Circuit breaker F1 alarm frame: 01 06 00 01 EE CRC.

[0257] 3.2 Contactor disconnection control:

[0258] Disconnect the corresponding contactor using a one-to-one mapping rule (e.g., circuit breaker F1 → contactor KM1).

[0259] Send Modbus RTU command: Device address | Function code 0x06 | Register address | Disconnect command 0x0000.

[0260] 4. System status reset

[0261] Restart the judgment process:

[0262] After the contactor is disconnected, the current status determination step of S102 is executed again to update the system status.

[0263] This embodiment calculates the absolute value of the three-phase current difference under the same circuit breaker ( If any difference exceeds the preset current difference value The system immediately detects a heating strip open circuit fault and sends an alarm signal with an address based on the circuit breaker number (e.g., F1), while simultaneously disconnecting the unique corresponding contactor (e.g., KM1). After fault handling, the current status determination process (S102) is immediately restarted, enabling system self-recovery. This solution transforms traditional manual maintenance into automated positioning, resolving the hidden danger of three-phase imbalance caused by a heating strip open circuit, and improving maintenance efficiency by over 80%.

[0264] This embodiment provides an adaptive electric heating control method for a paver screed. This method utilizes a current monitoring unit to collect real-time current values ​​of each phase from multiple circuit breakers in the electric heating control system. The logic control unit calculates the sum of the currents of each single phase based on these current values ​​and compares it with preset overload current values ​​and preset protection current values ​​to determine the current status. If the sum of the currents of each single phase is less than the preset overload current value, all contactors are activated, and full-power heating mode is initiated. If the sum of the currents of any single phase is between the preset overload and protection current values, zoned alternating heating control is executed based on the cumulative timing results. Once the sum of the currents of any single phase exceeds the preset protection current value, an overload alarm signal is immediately output and the system is shut down. Furthermore, for each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated and compared with a preset current difference value. If the difference exceeds the limit, a fault alarm signal is output and the corresponding contactor is disconnected, effectively avoiding generator overload risks and enabling rapid location of heating strip open-circuit faults.

[0265] This application also provides a partial embodiment of an adaptive paver screed electric heating control method, the specific control method of which is as follows:

[0266] When the paver turns on the electric heating function to heat the screed, the control switch first issues a command to turn on the electric heating function. After receiving the command, the logic control unit will control the engine speed to reach more than 1400 revolutions per minute, thereby driving the generator to rotate and reach the rated voltage for the electric heating strip to work.

[0267] The logic control unit determines the heating element's temperature based on the current temperature value from the temperature sensor and a preset electric heating temperature value. If the current sensor temperature value is lower than the preset electric heating temperature value, heating is initiated, driving the contactor to engage and supplying power to the electric heating strip to heat the ironing board. If the current sensor temperature value is higher than the electric heating temperature value, the contactor is disconnected, stopping the power supply to the electric heating strip.

[0268] The control method of this invention involves the current monitoring unit monitoring the three-phase current values ​​at the upper end of each circuit breaker in real time during the process and feeding them back to the logic control unit. The logic control unit determines the state of the electric heating system based on the current feedback values ​​and adopts different control methods accordingly.

[0269] The present invention allows setting an overload current value in the logic control unit. , protection current value The difference between the two currents Alternating heating time Electric heating temperature difference These parameters are used to calibrate the various states of electric heating.

[0270] For typical alternators, manufacturers will specify two key parameters: rated power. Rated capacity Taking the Stanford PI144J2 generator as an example, its rated power... Rated capacity Rated voltage Because the communication system has P= Meanwhile, the electric heating strip is a resistive load with a low power factor. The value is 1, therefore = / .

[0271] Based on the generator's characteristics, it is permissible to operate for 53 minutes every 12 hours at a power level above 110% and below the rated capacity.

[0272] 110% of rated current is The generator's maximum allowable current is 60A.

[0273] Therefore, the generator can operate without restriction when the current is less than 53.4A; when the current is greater than 53.4A but less than 60A, it can operate for 53 minutes every 12 hours; and it must stop operating immediately when the current is greater than 60A.

[0274] Overload current value of parameters Set the protection current value to 110% of the generator's rated current. Set to the maximum allowable current for the generator.

[0275] When the sum of the single-phase currents is less than the overload current For example, in a three-phase circuit, the current from circuit breaker F1 to phase U is... The current in phase U of circuit breaker F2 is The current in phase U of circuit breaker F3 is The current in phase U of circuit breaker F4 is The current in phase U of circuit breaker F5 is Similarly, for phases V and W, we have

[0276] ,

[0277] and ,

[0278] and .

[0279] At this time, the electric heating system is operating normally, and the five contactors are engaged synchronously. When properly configured, this setting maximizes the generator's power to meet the needs of various types and widths of ironing sheets.

[0280] When the sum of the single-phase currents is greater than the overload current And less than the protection current At that time, that is:

[0281] ,

[0282] or ,

[0283] or .

[0284] At this time, the logic control unit accumulates a timer for this state. If the accumulated time is less than 53 minutes within 12 hours, all 5 contactors engage synchronously, and all ironing plates heat up simultaneously. If the accumulated time is 53 minutes or more within 12 hours, the zone heating function is executed. KM1 / KM2 / KM4 is the first group, KM1 / KM3 / KM5 is the second group, and KM2 / KM4 / KM3 / KM5 is the third group. The three groups cycle through heating, and the time for each group is the alternating heating time. This setting protects the electric heating system while maintaining its function by appropriately reducing the heating power when the actual required power is much greater than the generator power.

[0285] When the sum of the single-phase currents is greater than the protection current At that time, that is:

[0286] ,

[0287] or ,

[0288] or .

[0289] The logic control unit outputs a current protection alarm, which is displayed on the human-machine interface of the logic control unit, and at the same time shuts down the electric heating function.

[0290] For the same circuit breaker F, with proper configuration, the electric heating strips should be evenly distributed across the three phases of the circuit breaker, resulting in minimal current differences between the corresponding phases and consequently, a small current in the neutral line N. If the three-phase current difference increases, the neutral current will increase, and severe three-phase imbalance can cause the neutral line N to overheat, leading to an electrical accident. When a circuit breaker experiences an open circuit fault, the current in the phase containing the heating strip will decrease, thus increasing the current difference between the phases. Therefore, we set two parameters related to the current difference. This is the rated operating current value for a single heating bar.

[0291] When the difference between the two phase currents on the same circuit breaker is less than the difference between the two phase currents. For example:

[0292] ,

[0293] or ,

[0294] or .

[0295] The logic control unit outputs the corresponding alarm signal and disconnects the contactor for that signal. This enables the detection and alarm of the location of the heating strip open circuit fault, preventing electrical faults caused by three-phase imbalance and improving the convenience of maintenance when the heating strip malfunctions.

[0296] Figure 2 This is a connection diagram of the adaptive paver screed electric heating control system provided in this application, as shown below. Figure 2 As shown, this embodiment provides an adaptive paver screed electric heating control system, which applies... Figure 1 The adaptive paver screed electric heating control method described in the embodiment includes a control system comprising:

[0297] The current monitoring unit is used to acquire the phase current values ​​of multiple circuit breakers in the electric heating control system in real time.

[0298] A logic control unit is connected to the current monitoring unit. The logic control unit is used to calculate the sum of the single-phase currents based on the current values ​​of each phase; and compare the sum of the single-phase currents with a preset overload current value and a preset protection current value to perform current status determination.

[0299] A control execution unit, connected to the logic control unit, is configured to: control all contactors to engage to execute full-power heating mode when the sum of all single-phase currents is less than the preset overload current value; execute zoned alternating heating control based on cumulative timing results when the sum of any single-phase current is greater than the preset overload current value but less than the preset protection current value, wherein the cumulative timing results are used to indicate the duration of the overload state; and output an overload alarm signal and shut down the electric heating control system when the sum of any single-phase current is greater than the preset protection current value.

[0300] The fault diagnosis unit is connected to the current monitoring unit and the logic control unit. The fault diagnosis unit is used to calculate the current difference between any two phases under the same circuit breaker based on the current values ​​of each phase for each circuit breaker; compare the current difference with a preset current difference value; and output the fault alarm signal corresponding to the circuit breaker and disconnect the contactor corresponding to the circuit breaker when the difference is greater than the preset current difference value.

[0301] Specifically, the current monitoring unit includes:

[0302] A current transformer array is used to collect the instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker;

[0303] A filtering module is connected to the current transformer array. The filtering module is used to filter the instantaneous current value and output the steady-state current value as the current value of each phase.

[0304] Specifically, the logic control unit includes:

[0305] The summation calculation module is used to calculate the sum of the currents of phase U, phase V and phase W on the multiple circuit breakers respectively, and output the sum of phase U current, the sum of phase V current and the sum of phase W current;

[0306] A comparison module is connected to the summation calculation module. The comparison module is used to compare the summation of U-phase current, V-phase current, and W-phase current with the preset overload current value and the preset protection current value, respectively.

[0307] A status identifier generation module is connected to the comparison module. The status identifier generation module is used to generate a current status identifier based on the comparison result. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

[0308] In practice, the adaptive paver screed electric heating control system provided in this embodiment specifically includes:

[0309] I. System Overall Structure and Connection Method

[0310] This control system includes a current monitoring unit, a logic control unit, a control execution unit, and a fault diagnosis unit. Each unit is directly connected via an industry-standard physical interface.

[0311] Current monitoring unit output → RS-485 communication cable → logic control unit input (transmits steady-state current value).

[0312] Logic control unit output → Digital I / O port → Control execution unit input (transmission current status indicator);

[0313] Current monitoring unit data bus → parallel data line → fault diagnosis unit input terminal (shared steady-state current value).

[0314] Fault diagnosis unit control line → control signal line → logic control unit reset port (send reset command);

[0315] The system is powered by a 24V DC regulated power supply, and all unit grounding wires are connected to a common grounding copper busbar to ensure electrical safety.

[0316] II. Detailed Implementation of the Current Monitoring Unit

[0317] The current monitoring unit includes a current transformer array and a filtering module:

[0318] 1. Current transformer array

[0319] Physical structure: 18 independent toroidal core current transformers (core material is silicon steel sheet, accuracy ±0.5%), arranged in groups of 3, with each group corresponding to one circuit breaker (F1-F6). Installation position: The U-phase current transformer is clipped to the surface of the U-phase copper busbar at the top of the circuit breaker; the V-phase and W-phase are similar.

[0320] Function and purpose: Directly acquires instantaneous current value and outputs 0-5V analog signal (range 0-100A) to eliminate construction vibration interference.

[0321] Connection method: The output line of the secondary side of the current transformer is directly connected to the input terminal of the filter module through a shielded twisted pair cable.

[0322] 2. Filtering module

[0323] Hardware components: A second-order low-pass filter circuit board based on an operational amplifier, with a cutoff frequency of 10Hz.

[0324] Processing logic: The Butterworth low-pass filter algorithm is used to input the instantaneous current value, remove high-frequency noise, and output the steady-state current value.

[0325] Function and effect: Ensures that the steady-state current value fluctuates within the range of ≤ ±0.2A, providing a stable data source for subsequent units.

[0326] Output interface: The output of the filter module is connected to the logic control unit via an RS-485 interface chip (MAX485).

[0327] III. Detailed Implementation of the Logic Control Unit

[0328] The logic control unit includes a summation calculation module, a comparison module, and a status flag generation module, which are integrated into the PLC controller (processor is ARM Cortex-M4):

[0329] 1. Total Calculation Module

[0330] Processing logic: An arithmetic accumulation algorithm is used, inputting the steady-state current values ​​of the six circuit breakers (…). to ), phase by phase, independent accumulation:

[0331] U-phase sum = .

[0332] The sum of phase V is calculated in the same way as the sum of phase W.

[0333] Function and effect: Output accuracy 0.1A, processing delay <1ms, ensuring real-time performance.

[0334] 2. Comparison Module

[0335] 2.1 Parameter storage: Built-in EEPROM stores preset overload current values ​​(e.g., 53A) and preset protection current values ​​(e.g., 60A).

[0336] 2.2 Comparison Logic: Parallel execution of three-way threshold comparison:

[0337] Compare the total U-phase current with the preset overload current value and the preset protection current value;

[0338] The sum of phase V and the sum of phase W are independently compared with the same threshold.

[0339] 2.3 Function and Effect: Avoids three-phase interference and generates accurate status signals.

[0340] 3. Status Identifier Generation Module

[0341] 3.1 Encoding rule: Output a 3-bit binary code based on the comparison result:

[0342] All phase sum < overload value → Normal indicator (0x01);

[0343] If the sum of any phases is greater than or equal to the overload value and less than the protection value, then the overload indicator (0x02) is displayed.

[0344] If the sum of any phase is greater than or equal to the protection value, then the protection flag (0x03) is displayed.

[0345] 3.2 Function and Effect: Identifies the output to drive the control execution unit, with a response time ≤2ms.

[0346] IV. Detailed Implementation of the Control Execution Unit

[0347] The control and execution unit is a relay drive circuit board:

[0348] 1. Hardware Structure: Six electromagnetic relays (contact capacity 30A), each relay corresponding to one contactor (KM1-KM6). The relay coil drive circuit is connected to the output port of the logic control unit via optocoupler isolation.

[0349] 2. Execution logic:

[0350] 2.1 Normal indicator received (0x01): Close all relay contacts and engage contactors KM1-KM6.

[0351] 2.2 Upon receiving an overload flag (0x02): Start a timer to accumulate the overload duration; if the accumulated duration is less than a preset threshold (e.g., 120 seconds), maintain full engagement; if the accumulated duration is greater than or equal to the preset threshold, cyclically control the three contactors:

[0352] Group 1: Engage KM1 / KM2 / KM4, disengage the rest;

[0353] Group 2: Engage KM1 / KM3 / KM5, disengage the rest;

[0354] Group 3: Engage KM2 / KM3 / KM4 / KM5, disengage the rest.

[0355] 2.3 Upon receiving the protection flag (0x03): Disconnect all relays and trigger the audible and visual alarm.

[0356] 3. Function and effect: Reduce peak power by 40% through group control, thus protecting the generator.

[0357] V. Detailed Implementation of the Fault Diagnosis Unit

[0358] The fault diagnosis unit is implemented based on an FPGA chip:

[0359] 1. Input connection: Receive steady-state current value from the current monitoring unit via parallel data bus (synchronized with the logic control unit).

[0360] 2. Diagnostic Logic:

[0361] 2.1 Perform the following steps for each circuit breaker (F1-F6):

[0362] Calculate the absolute values ​​of the UV phase current difference, VW phase current difference, and WU phase current difference;

[0363] If any difference is greater than the preset current difference (e.g., 5A), the corresponding heating strip is determined to be open circuit.

[0364] 2.2 Execution Actions:

[0365] Send Modbus RTU alarm frames to HMI (e.g., circuit breaker F1 fault frame: 01 06 00 01 EE CRC);

[0366] Output a low-level signal to disconnect the corresponding contactor (F1→KM1, F2→KM2, ..., F6→KM6).

[0367] Send a hardware reset command to the logic control unit.

[0368] 3. Function and effect: Locates open circuit faults within 100ms, improving maintenance efficiency by 80%.

[0369] VI. Overall System Performance

[0370] 1. The current monitoring unit outputs a stable current value through the Butterworth filtering algorithm to eliminate on-site interference.

[0371] 2. The parallel comparison mechanism of the logic control unit ensures that status indicators are generated in real time, avoiding control delays.

[0372] 3. The grouping timing control of the control execution unit (such as the KM1 / KM2 / KM4 combination) optimizes power distribution and extends generator life.

[0373] 4. The differential calculation logic of the fault diagnosis unit accurately locates the broken heating strip, reducing manual troubleshooting time.

[0374] All units work together through standardized interfaces (RS-485, digital I / O) to achieve fully automatic protection and fault handling of the paver screed heating system.

[0375] This application also provides an optional structure for an adaptive paver screed electric heating control system. Figure 3 This is a schematic diagram of the structure of the adaptive paver screed electric heating control system provided in this application, as shown below. Figure 3 As shown, the present invention aims to adapt to the power requirements of various screeds by having the paver current monitoring unit, insulation monitoring unit, and logic control unit work together to ensure the safety and stability of the electric heating system. It switches the electric heating mode according to the generator's maximum power and the real-time current status of the electric heating system, so that the electric heating system can output power fully and effectively protect the electric heating system when the power is insufficient.

[0376] In addition, the present invention provides better diagnostic functions, making it easier for operators or maintenance personnel to find faults in electric heating strips.

[0377] The paver electric heating system of the present invention consists of a generator, circuit breaker, contactor, control switch, temperature sensor, logic control unit, insulation monitoring unit, electric heating bar, and current monitoring unit.

[0378] The generator is driven by the diesel engine transfer case belt and is the power supply unit of the electric heating system.

[0379] The function of circuit breakers, contactors, and their wiring is to distribute electrical energy to each heating bar and to provide short-circuit protection.

[0380] The electric heating system typically has five sets of circuit breakers and contactors, corresponding to the basic center and left ironing plates, the left extension section, the right ironing plate, and the right extension section, respectively. Its external wiring is evenly distributed according to the power of the electric heating strips on the ironing plates.

[0381] The control switch is the command unit for electric heating, which turns the electric heating system on or off, or switches between automatic and manual modes.

[0382] The temperature sensor is used to measure the temperature of the ironing board and feed the temperature value back to the logic control unit in real time to control the electric heating status.

[0383] The logic control unit has functions of human-machine interaction, signal input / output, and logic operation processing. It controls the on / off switching of contactors in the electric heating system based on input signals from control switches and temperature sensors, thereby automatically controlling the operation of the electric heating system. Simultaneously, the logic control unit supports parameter setting and the display of various information, such as real-time temperature and set temperature.

[0384] The insulation monitoring unit is used to detect the insulation resistance between the power line and the shielded ground wire PE, thereby detecting the insulation of the electric heating system and ensuring electrical safety.

[0385] Electric heating strips are the execution units of electric heating systems. Depending on the type and width of the ironing board, electric heating strips of different lengths or powers are arranged, and their number increases with the number of sections of the ironing board.

[0386] The current monitoring unit is used to monitor the current of the electric heating system in real time. Different current values ​​cause the electric heating system to operate in different states, ensuring stable operation when adapted to different types and widths of ironing plates. This maximizes generator power while limiting the maximum operating current, protecting the generator. Simultaneously, with the electric heating strips' power evenly distributed, it displays the three-phase current values ​​of each circuit breaker input line, using uneven changes in the three-phase current to pinpoint the location of the faulty heating strip.

[0387] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0388] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for controlling the electric heating of an adaptive paver screed, characterized in that, The method includes: The current monitoring unit acquires the phase current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time. In the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with the preset overload current value and the preset protection current value to perform current state determination. When the sum of all the single-phase currents is less than the preset overload current value, control all contactors to engage to execute the full-power heating mode. When the sum of any single-phase current is greater than the preset overload current value and less than the preset protection current value, zoned alternating heating control is executed based on the cumulative timing result, wherein the cumulative timing result is used to indicate the duration of the state where the sum of any single-phase current is greater than the preset overload current value and less than the preset protection current value; the execution of zoned alternating heating control based on the cumulative timing result specifically includes: When the current status indicator is an overload indicator, the overload duration accumulation timer is started. If the cumulative duration is less than the preset duration threshold, control all contactors to engage; If the cumulative duration is greater than or equal to the preset duration threshold, the contactors are divided into three groups for cyclic execution: Group 1: KM1, KM2, and KM4 are controlled to engage, while KM3 and KM5 are disengaged; Group 2: KM1, KM3, and KM5 are controlled to engage, while KM2 and KM4 are disengaged; Group 3: KM2, KM3, KM4, and KM5 are controlled to engage, while KM1 is disengaged; wherein, the engagement duration of each group is equal to the preset alternating heating time; When the sum of any of the single-phase currents exceeds the preset protection current value, an overload alarm signal is output and the electric heating control system is shut down. For each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase, and the current difference is compared with a preset current difference value; when the current difference is greater than the preset current difference value, the fault alarm signal corresponding to the circuit breaker is output and the contactor corresponding to the circuit breaker is disconnected.

2. The adaptive paver screed electric heating control method according to claim 1, characterized in that, The method of acquiring the phase current values ​​of each phase at the upper end of multiple circuit breakers in the electric heating control system in real time through the current monitoring unit includes: The instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker are collected by current transformers; The instantaneous current value is filtered to obtain the steady-state current value, which is used as the current value of each phase.

3. The adaptive paver screed electric heating control method according to claim 1, characterized in that, In the logic control unit, the sum of the single-phase currents is calculated based on the current values ​​of each phase, and the sum of the single-phase currents is compared with a preset overload current value and a preset protection current value to perform a current state determination, including: Calculate the sum of the currents in phase U, phase V, and phase W on the multiple circuit breakers respectively to obtain the sum of the currents in phase U, phase V, and phase W. The sum of the U-phase current, the sum of the V-phase current, and the sum of the W-phase current are compared with the preset overload current value and the preset protection current value, respectively. A current status identifier is generated based on the comparison results. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

4. The adaptive paver screed electric heating control method according to claim 3, characterized in that, When the sum of all the single-phase currents is less than the preset overload current value, controlling all contactors to engage to execute full-power heating mode includes: When the current status indicator is normal, a closing command is sent to all contactors; Monitor the contactor feedback signal, and once all contactors confirm engagement, maintain full-power heating until the temperature reaches the preset value.

5. The adaptive paver screed electric heating control method according to claim 3, characterized in that, When the sum of any of the single-phase currents exceeds the preset protection current value, an overload alarm signal is output and the electric heating control system is shut down, including: When the current status indicator is a protection indicator, the audible and visual alarm is triggered to output the overload alarm signal; Simultaneously send disconnect commands to all contactors and display the off status on the human-machine interface.

6. The adaptive paver screed electric heating control method according to claim 1, characterized in that, For each circuit breaker, the current difference between any two phases under the same circuit breaker is calculated based on the current values ​​of each phase, and the current difference is compared with a preset current difference value. When the current difference is greater than the preset current difference value, output the fault alarm signal corresponding to the circuit breaker and disconnect the contactor corresponding to the circuit breaker, including: For the current circuit breaker, calculate the absolute values ​​of the current difference between phases UV, VW, and WU respectively; When the absolute value of any of the current differences is greater than the preset current difference value, it is determined that the heating strip corresponding to the current circuit breaker has an open circuit fault. Output a fault alarm signal containing the circuit breaker number corresponding to the current circuit breaker, and disconnect the contactor uniquely corresponding to the current circuit breaker. After disconnecting the contactor corresponding to the current circuit breaker, re-execute the current state determination.

7. An adaptive paver screed electric heating control system, characterized in that, The system employs the adaptive paver screed electric heating control method according to any one of claims 1-6, and the system comprises: The current monitoring unit is used to acquire the phase current values ​​of multiple circuit breakers in the electric heating control system in real time. A logic control unit is connected to the current monitoring unit. The logic control unit is used to calculate the sum of the single-phase currents based on the current values ​​of each phase; and compare the sum of the single-phase currents with a preset overload current value and a preset protection current value to perform current status determination. A control execution unit, connected to the logic control unit, is configured to: control all contactors to engage to execute full-power heating mode when the sum of all single-phase currents is less than the preset overload current value; execute zoned alternating heating control based on cumulative timing results when the sum of any single-phase current is greater than the preset overload current value but less than the preset protection current value, wherein the cumulative timing results are used to indicate the duration of the overload state; and output an overload alarm signal and shut down the electric heating control system when the sum of any single-phase current is greater than the preset protection current value. The fault diagnosis unit is connected to the current monitoring unit and the logic control unit. The fault diagnosis unit is used to calculate the current difference between any two phases under the same circuit breaker based on the current values ​​of each phase for each circuit breaker; compare the current difference with a preset current difference value; and output the fault alarm signal corresponding to the circuit breaker and disconnect the contactor corresponding to the circuit breaker when the difference is greater than the preset current difference value.

8. The adaptive paver screed electric heating control system according to claim 7, characterized in that, The current monitoring unit includes: A current transformer array is used to collect the instantaneous current values ​​of phase U, phase V and phase W at the upper end of each circuit breaker; A filtering module is connected to the current transformer array. The filtering module is used to filter the instantaneous current value and output the steady-state current value as the current value of each phase.

9. The adaptive paver screed electric heating control system according to claim 7, characterized in that, The logic control unit includes: The summation calculation module is used to calculate the sum of the currents of phase U, phase V and phase W on the multiple circuit breakers respectively, and output the sum of phase U current, the sum of phase V current and the sum of phase W current; A comparison module is connected to the summation calculation module. The comparison module is used to compare the summation of U-phase current, V-phase current, and W-phase current with the preset overload current value and the preset protection current value, respectively. A status identifier generation module is connected to the comparison module. The status identifier generation module is used to generate a current status identifier based on the comparison result. The current status identifier includes a normal identifier, an overload identifier, or a protection identifier.

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