Temperature control device based on Modbus high-voltage live display

Abstract

The invention relates to the technical field of intelligent temperature control of power equipment, in particular to a temperature control system based on a Modbus high-voltage live display, which comprises a state sensing and communication module, a logic linkage control module, an execution driving module, a parameter configuration and feedback module and a fault diagnosis module. The system collects high-voltage live-line state and temperature data in real time through a Modbus RTU protocol, dynamically switches temperature control strategies according to the live-line state, controls a fan and a heater in a linkage mode, and supports remote parameter configuration and fault warning. According to the invention, intelligent linkage of temperature control and electrified state of the high-voltage switch cabinet can be realized, and the safety and energy efficiency of equipment are improved.

Description

Technical Field

[0001] This invention belongs to the field of intelligent monitoring and temperature control technology for power equipment, specifically a temperature control system based on a Modbus high-voltage live display. Background Technology

[0002] With the development of smart grids and power automation technologies, the monitoring of the operating status and temperature control management of high-voltage switchgear are receiving increasing attention. High-voltage live-line indicators, as key devices for determining whether primary equipment is energized, can significantly improve the intelligence level and operation and maintenance efficiency of power distribution systems if they can integrate temperature monitoring and control functions and achieve data interaction through standardized communication protocols (such as Modbus). However, although some existing technologies combine high-voltage live-line indicators with temperature monitoring, they still have significant shortcomings in terms of communication protocol compatibility, system integration, and temperature control response mechanisms.

[0003] A search revealed a patent, CN103746296B, for an intelligent microcomputer protection device with operation status display, wireless temperature measurement, and automatic communication protocol conversion functions, published on May 4, 2016. This patent integrates a high-voltage live display, an infrared sensor, and a wireless temperature measurement module, enabling temperature monitoring and status display of equipment within the switchgear, and supporting automatic communication protocol conversion for data upload via Ethernet or fiber optic interfaces. However, this solution does not explicitly employ industrial standard communication protocols such as Modbus for temperature control data interaction. Its "automatic protocol conversion" function focuses on compatibility with the upper-level scheduling system, rather than real-time closed-loop control for the local temperature control execution unit. Furthermore, its temperature control function exists only as an auxiliary function, lacking a deep integration design for the linkage between temperature control logic and high-voltage live status, making it difficult to achieve intelligent start / stop or dynamic threshold adjustment based on the equipment's live status.

[0004] A search revealed a smart cabinet-type reactive power compensation device with publication number CN103248057B, published on January 20, 2016. This patent incorporates a temperature and humidity controller, a high-voltage live display device, and a fan as temperature control actuators within the compensation cabinet, enabling internal environmental temperature monitoring and remote monitoring capabilities. However, the temperature control system and the high-voltage live display function are independent of each other, lacking a logical connection. More importantly, it fails to mention using common industrial communication protocols such as Modbus for temperature control parameter configuration or status reporting, making it difficult to integrate into existing Modbus-based substation automation systems and limiting its application scalability in standardized intelligent power distribution scenarios.

[0005] The aforementioned problems indicate that while existing technologies address high-voltage live display and temperature control functions, they generally lack a design that deeply integrates high-voltage live status information with temperature control strategies via the Modbus protocol. This results in shortcomings in communication standardization, intelligent control, and functional linkage within the system. Therefore, this invention proposes a temperature control system based on a Modbus high-voltage live display. The aim is to achieve efficient coordination between high-voltage live status and temperature control logic through the Modbus protocol, improving system compatibility, response speed, and intelligent operation and maintenance levels, thus meeting the demands of modern intelligent power distribution equipment for high integration, standardized communication, and status-linked control. Summary of the Invention

[0006] In view of the aforementioned existing problems, the present invention is proposed.

[0007] Therefore, this invention provides a temperature control system based on a Modbus high-voltage live display, which solves the problems of functional separation between existing high-voltage live display devices and temperature control systems, lack of linkage mechanism for dynamically adjusting temperature control strategies based on the energized state of the equipment, and failure to use the Modbus industrial standard protocol for local closed-loop control communication.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a temperature control system based on a Modbus high-voltage live display, comprising,

[0010] The status awareness and communication module collects the energized status signal of the primary equipment and the internal temperature data of the switch cabinet through the high-voltage energized sensor and the temperature sensor, respectively, and encapsulates the data into Modbus RTU frame format and sends it to the main controller through RS-485 bus.

[0011] The logic linkage control module receives the energized status and temperature value after parsing the Modbus frame, and generates fan start / stop commands and heater power levels according to the preset energized status-temperature control mapping table.

[0012] The execution drive module receives the fan start / stop command and the heater power level, and controls the on / off of the fan motor and the PWM duty cycle output of the heater through a solid-state relay array; the parameter configuration and feedback module responds to the Modbus write request sent by the main controller, performs register-level configuration of temperature control threshold, hysteresis interval and linkage mode, and sends the current execution status, temperature reading and equipment power-on flag back to the main controller.

[0013] The fault diagnosis module monitors temperature sensor disconnection, fan stall, and heater overcurrent signals in real time. When an abnormality is detected, it writes the fault code to the specified address of the Modbus holding register and triggers a local LED flashing alarm.

[0014] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the following is provided: In the status sensing and communication module, the high-voltage live sensor adopts a capacitive voltage divider probe, its input end is connected to the primary bus, and its output end is connected to the positive input end of the comparator via an isolation amplifier. The negative input end of the comparator is connected to an adjustable reference voltage, and the comparator output signal is sent to the GPIO pin of the microcontroller after optocoupler isolation; the temperature sensor adopts a PT100 platinum resistance thermometer, which is connected to the constant current source circuit in a two-wire connection method. The voltage sampling value is converted by a 24-bit Σ-Δ ADC and then input to the microcontroller; the microcontroller has a built-in Modbus protocol stack, which maps the GPIO level state to 0x01 or 0x00, converts the ADC conversion result into Celsius temperature value according to the IEC 60751 standard, and packages it to Modbus holding register addresses 40001 (live state) and 40002 (temperature value), and drives the RS-485 bus through the MAX3485 chip in 9600bps, 8N1 format.

[0015] As a preferred embodiment of the temperature control system based on a Modbus high-voltage live display according to the present invention, the following is provided: In the logic linkage control module, the microcontroller internally stores a live state-temperature control mapping table, which contains two sub-tables: when the live state is 0x01, a high-load temperature control strategy is enabled, setting the start temperature threshold to 45℃, the stop temperature to 40℃, and the hysteresis interval to 5℃; when the live state is 0x00, a low-power strategy is enabled, setting the start temperature threshold to 35℃ and the stop temperature to 30℃; the microcontroller reads Modbus input registers 40001 and 40002 every 100ms. If the current temperature is ≥ the start threshold and the fan is off, the fan control flag is set; if the current temperature is ≤ the stop temperature and the fan is on, the fan control flag is cleared; the heater power level is divided into four levels: 0%, 30%, 60%, and 100% based on the linear interpolation of the difference between the temperature and the start threshold, and the PWM duty cycle is determined by looking up a table.

[0016] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, wherein: in the execution drive module, the fan control signal is connected to the control terminal of the solid-state relay SSR1, and the AC output terminal of SSR1 is connected in series in the fan motor power supply circuit; the heater PWM signal is input to the IN pin of the MOSFET driver chip IR2104 after optocoupler isolation, the HO pin of IR2104 drives the gate of the N-channel MOSFET IRF540, the drain of IRF540 is connected to one end of the heater, the source is grounded, and the other end of the heater is connected to a 24V DC power supply; the PWM frequency is fixed at 10kHz, the duty cycle is output by the timer channel of the microcontroller, and after low-pass filtering, it forms an equivalent analog control quantity.

[0017] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, wherein: in the parameter configuration and feedback module, Modbus holding register address 40010 is used to write the fan start temperature threshold, address 40011 is used to write the stop temperature, and address 40012 is used to write the linkage mode enable flag; the microcontroller scans these registers in each Modbus polling cycle, and if a write operation is detected, it updates the internal temperature control parameters; at the same time, the microcontroller writes the current fan status (0 = off, 1 = on) to register 40020, the current duty cycle percentage of the heater to register 40021, and the original value of the live state to register 40022 for the host computer to read in real time.

[0018] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the fault diagnosis module includes: a 10Ω sampling resistor connected in series in the PT100 circuit, whose voltage is differentially amplified and input to a comparator; if the voltage is below 0.1V for 1 second, it is determined that the sensor is disconnected; a Hall current sensor ACS712 is connected in series in the fan motor power supply circuit, whose output voltage is sampled by an ADC; if the current after the fan starts is less than 20% of the rated value and lasts for 500ms, it is determined that the fan is stalled; the heater circuit is also connected to ACS712; if the current exceeds 150% of the rated value and lasts for 200ms, it is determined that the heater is overcurrent; the microcontroller encodes disconnection, stall, and overcurrent as 0x10, 0x20, and 0x40 respectively, writes them into the holding register 40030, and controls the control panel LED to flash the corresponding number of times at a frequency of 1Hz.

[0019] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the capacitive voltage divider probe of the high-voltage live sensor is installed 5mm directly below the primary busbar inside the switchgear and fixed by epoxy resin potting. Its signal line adopts a double-shielded cable, with the inner shielding layer connected to the probe shell and the outer shielding layer connected to the cabinet grounding busbar. The temperature sensor PT100 is encapsulated in a stainless steel sheath, and the end of the sheath is welded to a metal bracket near the heating element inside the switchgear to ensure the shortest heat conduction path.

[0020] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the RS-485 bus adopts a daisy-chain topology, with a 120Ω terminating resistor connected in parallel at the farthest end of the bus, and the DE / RE pins of the microcontroller are controlled by the same GPIO to ensure that the transmit / receive switching timing meets the TTL to RS-485 conversion requirements.

[0021] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the microcontroller is an STM32F103C8T6, which stores the live state-temperature control mapping table and fault coding rules in its internal Flash, maintains the current temperature control state machine in SRAM, configures timer TIM2 in PWM output mode, and configures USART1 as a Modbus communication interface.

[0022] As a preferred embodiment of the temperature control system based on Modbus high-voltage live display described in this invention, the solid-state relay SSR1 has an input control voltage of 3.3V, an output withstand voltage of 250VAC, and a rated current of 10A; the MOSFET IRF540 has an on-resistance of 0.077Ω, a maximum drain-source voltage of 100V, a gate drive voltage provided by an IR2104 bootstrap circuit, and a bootstrap capacitor of 1μF ceramic capacitor. Attached Figure Description

[0023] Figure 1 This is a block diagram of the overall structure of the temperature control system based on the Modbus high-voltage live display of the present invention, showing the connection relationship between the status sensing and communication module, the logic linkage control module, the execution drive module, the parameter configuration and feedback module, and the fault diagnosis module.

[0024] Figure 2 This is a schematic diagram of the circuit structure of the state sensing and communication module in this invention, including a high-voltage live sensor, a temperature sensor, an isolation amplifier, a comparator, an optocoupler, a constant current source, a Σ-ΔADC, and an RS-485 communication interface.

[0025] Figure 3This is a partial circuit connection diagram of the execution drive module and the fault diagnosis module in this invention, including a solid-state relay, a MOSFET drive circuit, a current sampling unit, and an LED alarm indication unit. Detailed Implementation

[0026] 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.

[0027] Specific implementation examples are given below.

[0028] This invention provides a temperature control system based on a Modbus high-voltage live display, the specific implementation of which is as follows; Figure 1 As shown, the system consists of five parts: a status perception and communication module, a logic linkage control module, an execution drive module, a parameter configuration and feedback module, and a fault diagnosis module. Each module uses a microcontroller as its core for data interaction and instruction execution. The microcontroller is an STM32F103C8T6, which integrates a USART1 serial port, multiple general-purpose timers, GPIO pins, and SRAM and Flash memory units to implement functions such as Modbus protocol parsing, temperature control logic judgment, PWM signal generation, and register data maintenance.

[0029] In the state awareness and communication module, such as Figure 2As shown, the high-voltage live sensor is a capacitive voltage divider probe. Its input terminal is directly installed 5mm below the primary busbar inside the switchgear and fixed with epoxy resin potting to ensure electrical insulation performance and mechanical stability. The output terminal of the probe is connected to the input terminal of an isolation amplifier. The output terminal of the isolation amplifier is connected to the positive input terminal, and the negative input terminal of the comparator is connected to an adjustable reference voltage source to set the live detection threshold. The output signal of the comparator is sent to a GPIO pin of the microcontroller after optocoupler isolation. This pin is configured in input mode to read the status signal of whether the primary equipment is live. Meanwhile, the temperature sensor uses a PT100 platinum resistance thermometer, encapsulated in a stainless steel sheath. The end of the sheath is welded to a metal bracket near the heating element inside the switchgear to shorten the heat conduction path and improve the temperature measurement response speed. The PT100 uses a two-wire connection method, with one end connected to the output terminal of a constant current source and the other end grounded. The constant current source provides a constant 1mA current flowing through the PT100, forming a voltage signal proportional to the temperature at its two ends. This voltage signal is then processed by a Σ-ΔADC. After 24-bit high-precision analog-to-digital conversion, the data is sent to the microcontroller's data bus. The microcontroller has a built-in Modbus RTU protocol stack, which maps the high and low levels read from the GPIO pins to 0x01 (energized) or 0x00 (non-energized) in the Modbus holding register address 40001, and converts the digital output of the Σ-ΔADC 7 into a Celsius temperature value according to the IEC 60751 standard, and writes it to the holding register address 40002. Subsequently, the microcontroller packages the data from the two registers into a Modbus data packet via the USART1 interface in 9600bps, 8N1 format. RTU frames are used to drive the RS-485 transceiver (model MAX3485) to send data to the RS-485 bus; the DE / RE pins of the RS-485 transceiver are controlled by the same GPIO of the microcontroller, ensuring that the timing requirements for the conversion from TTL level to RS-485 differential level are met when switching between transmit and receive states; the RS-485 bus adopts a daisy-chain topology, with a 120Ω terminating resistor connected in parallel at the farthest end of the bus to suppress signal reflection;

[0030] In the logic linkage control module, the microcontroller's internal Flash memory stores a power-state-temperature control mapping table. This table contains two sub-strategies: when the power-state register 40001 reads a value of 0x01, a high-load temperature control strategy is activated, setting the fan start-up temperature threshold to 45℃, the stop temperature to 40℃, and the hysteresis interval to 5℃; when the read value is 0x00, a low-power strategy is activated, setting the start-up temperature threshold to 35℃ and the stop temperature to 30℃. The microcontroller reads input registers 40001 and 4x0002 every 100ms via a Modbus polling mechanism. The current value of 0002, if the current temperature is greater than or equal to the start threshold under the corresponding strategy and the fan is currently off, then the internal fan control flag is set; if the current temperature is less than or equal to the stop temperature and the fan is on, then the flag is cleared; the heater power level is linearly interpolated according to the difference between the current temperature and the start threshold, and divided into four levels: 0%, 30%, 60%, and 100%. The microcontroller determines the corresponding PWM duty cycle value by looking up a table and loads it into the capture / compare register of timer TIM2, thereby generating a PWM signal with the corresponding duty cycle;

[0031] Execution driver module such as Figure 3 As shown, the fan control signal is output from a GPIO pin of the microcontroller, which is connected to the input control terminal of a solid-state relay (SSR1). The input control voltage of the SSR1 is 3.3V, and its output is an AC normally open contact. One end of the SSR1 is connected to the 220VAC power phase line, and the other end is connected to the power supply terminal of the fan motor. The other end of the fan motor is connected to the neutral line, thus forming a complete fan power supply circuit. When the microcontroller outputs a high level, the SSR1 conducts, and the fan is powered on and runs; when the output is low, the SSR1 is turned off, and the fan stops. The heater control uses PWM. The PWM signal output by the microcontroller is first optically isolated and then input to the MOSFET driver. The IN pin of the IR2104 chip is connected to the gate of the N-channel MOSFET (IRF540), and the HO pin of the IR2104 is connected to the gate of the MOSFET. The drain of the IRF540 is connected to one end of the heater, and the source is grounded. The other end of the heater is connected to a 24V DC power supply. The bootstrap circuit of the IR2104 consists of a 1μF ceramic capacitor, which is used to provide the gate drive voltage during high-side drive. The PWM frequency is fixed at 10kHz, and the duty cycle is adjusted in real time by the timer channel of the microcontroller. After being driven by the IR2104, it controls the conduction time of the IRF540, thereby adjusting the average power of the heater. The PWM signal is equivalent to an analog control quantity at the heater end, realizing stepless temperature regulation.

[0032] The parameter configuration and feedback module achieves bidirectional communication through Modbus holding registers. The host computer can write the fan start temperature threshold to register address 40010, the stop temperature to 40011, and the linkage mode enable flag (0x01 indicates enabled linkage in energized state, 0x00 indicates disabled) via Modbus write requests. The microcontroller scans these register addresses in each Modbus polling cycle. If a write operation is detected, the internal temperature control parameter variables are updated. At the same time, the microcontroller writes the current fan operating status (0 indicates off, 1 indicates on) to register 40020, the current PWM duty cycle percentage (0~100) of the heater to register 40021, and the original state (without logic processing) of the high-voltage energized sensor to register 40022 for the host computer to read and monitor in real time.

[0033] Fault diagnosis module such as Figure 3 As shown, its hardware includes a Hall current sensor (model ACS712), a differential amplifier, and an LED alarm light; a 10Ω precision sampling resistor is connected in series in the PT100 circuit, and the voltage across the resistor is amplified by the differential amplifier and sent to the microcontroller's ADC channel; when the PT100 is working normally, a 1mA constant current source flows through the PT100 and the sampling resistor, generating a voltage drop of approximately 10mV across the sampling resistor; if the PT100 is disconnected, the current is zero, the voltage drop across the sampling resistor is less than 0.1V, and the microcontroller continuously monitors this voltage value. If it remains below the threshold for 1 second, it is determined that the temperature sensor is disconnected; a Hall current sensor is connected in series in the fan motor power supply circuit, and its output voltage is sampled by another ADC channel of the microcontroller; the rated starting current of the fan is 0. If the sampled current remains below 0.1A (i.e., 20% of the rated value) for 500ms after startup, it is determined that the fan is stalled. The heater circuit is also connected to another Hall current sensor. The rated current of the heater is 2A. If the current exceeds 3A (i.e., 150%) and lasts for 200ms, it is determined that the heater is overcurrent. The microcontroller encodes the above three faults as 0x10 (open circuit), 0x20 (stalled), and 0x40 (overcurrent) respectively, and writes them into the Modbus holding register 40030. At the same time, the LED alarm light on the microcontroller control panel flashes at a frequency of 1Hz. The number of flashes corresponds to the hexadecimal value of the fault code (e.g., open circuit flashes once, stalled flashes twice, and overcurrent flashes four times), realizing local visual alarm.

[0034] In terms of physical installation, the signal lines of the high-voltage live sensors use double-shielded cables. The inner shielding layer connects to the metal shell of the probe, and the outer shielding layer connects to the grounding busbar of the switch cabinet to suppress electromagnetic interference. The leads of the temperature sensor use high-temperature resistant silicone wire, which is inserted into the stainless steel sheath and soldered to the PT100 body. The sheath is fixed to the metal bracket with screws to ensure good thermal contact. The RS-485 communication line uses a twisted-pair shielded cable with the shielding layer grounded at one end to avoid ground loop interference. The solid-state relay is mounted on the PCB board, and its AC output terminal is connected to the external fan through a terminal block. The MOSFET is mounted on an aluminum heat sink, which is attached to the inner wall of the chassis with thermal grease to enhance heat dissipation. The core components such as the microcontroller, Σ-ΔADC, RS-485 transceiver, optocoupler, and constant current source are all arranged on the same four-layer PCB board. The power layer and ground layer are completely separated, and the digital ground and analog ground are connected at a single point through a ferrite bead to reduce noise coupling.

[0035] After the system powers on, the microcontroller first initializes GPIO, USART1, timer TIM2, ADC module, and internal registers. It then enters the main loop, performing a temperature control logic check every 100ms and continuously listening for Modbus communication interrupts. When a Modbus read request is received, the microcontroller extracts the corresponding data from internal variables or registers and packages it in response. When a write request is received, it parses the target register address and data, and updates the corresponding parameters. During the operation of the fan or heater, the fault diagnosis module runs synchronously, collecting current and sensor status in real time. Once a fault condition is triggered, it immediately freezes the output and updates the fault register and LED alarm status. The entire system communicates with the upper-level monitoring host via an RS-485 bus to achieve remote parameter configuration, status reading, and fault reporting. Simultaneously, it completes closed-loop control locally without relying on upper-level computer intervention, meeting the reliability and real-time requirements of industrial sites.

[0036] To enable those skilled in the art to fully understand and implement this invention, the following supplements the specific implementation principle of this invention in conjunction with a specific application scenario;

[0037] The temperature control system based on the Modbus high-voltage live display described in this invention is deployed in a 10kV intelligent substation to dynamically regulate the operating temperature of the circuit breaker compartment in the KYN28 high-voltage switchgear, and simultaneously indicate in real time whether the busbar is energized. After the system is powered on and initialized, the high-voltage live sensor first senses the status of the primary busbar: since the capacitive voltage divider probe is installed 5mm directly below the busbar, when the busbar is energized, the AC voltage it induces is isolated and amplified by the isolation amplifier and then sent to the positive input of the comparator, compared with the preset reference voltage (corresponding to approximately 3kV busbar voltage). The comparator compares the voltage threshold. If the voltage is higher than the threshold, the comparator outputs a high level, which is then sent to the GPIO pin of the microcontroller after being electrically isolated by an optocoupler. The microcontroller then sets Modbus register 40001 to 0x01, indicating that the device is powered on; otherwise, it is set to 0x00. At the same time, the PT100 platinum resistance thermometer used in the temperature sensor can quickly respond to local temperature rises because it is in close contact with the metal bracket near the circuit breaker pole. The 1mA current provided by the constant current source flows through the PT100 to form a millivolt-level voltage. This signal is converted by the Σ-Δ ADC with 24-bit resolution, and then the microcontroller converts it into an accurate Celsius temperature according to the IEC 60751 standard and writes it into register 40002, thereby completing the data acquisition and standardized packaging of the status sensing and communication module.

[0038] Subsequently, the logic linkage control module dynamically switches the temperature control strategy based on the value of register 40001: when the system detects that the bus is energized (40001 = 0x01), the microcontroller calls the high-load strategy from the internal Flash, setting the fan start threshold to 45℃ and the stop threshold to 40℃; if the bus is not energized (40001 = 0x00), it switches to the low-power strategy, reducing the start / stop thresholds to 35℃ and 30℃ respectively; the microcontroller reads the current values ​​of 40001 and 40002 every 100ms. If the current temperature is 46℃ and the fan is off, it sets the fan control flag and outputs a high-level signal to the execution drive module; this signal drives the solid-state relay. When the electrical circuit is turned on, the 220VAC power supply is connected to the fan motor circuit, and the fan begins forced heat dissipation. For heating requirements (such as anti-condensation in winter), when the temperature is lower than the set threshold, the microcontroller determines the PWM duty cycle by looking up a table based on the difference between the current temperature and the start threshold—for example, when the difference is 8℃, it corresponds to the 60% power level. The timer TIM2 then outputs a PWM wave with a duty cycle of 60% and a frequency of 10kHz, which is sent to the IN pin of the MOSFET driver chip after optocoupler isolation. The IR2104 maintains the high-side drive capability through the bootstrap capacitor, controls the conduction time of the N-channel MOSFET, and enables the 24V DC heater to obtain an equivalent average voltage of 14.4V, realizing stepless temperature regulation.

[0039] During system operation, the parameter configuration and feedback module continuously responds to Modbus commands from the upper-level monitoring host: maintenance personnel can write a new start-up temperature (e.g., 42℃) to register 40010 via the background. After the microcontroller detects the write operation in the next round of polling, it immediately updates the internal threshold variable without restarting the system. At the same time, the current fan status (register 40020), the actual duty cycle of the heater (register 40021), and the original energized signal (register 40022) are periodically refreshed for real-time access by the remote monitoring platform.

[0040] The fault diagnosis module simultaneously executes multiple protections: If the PT100 disconnects due to loose wiring, the constant current source circuit current returns to zero, and the voltage drop across the 10Ω sampling resistor falls below 0.1V. The signal amplified by the differential amplifier is continuously monitored by the microcontroller's ADC channel. If this state persists for 1 second, it is determined that the sensor is disconnected, fault code 0x10 is written to register 40030, and the LED alarm light is driven to flash once at a frequency of 1Hz. If the Hall current sensor detects that the current is consistently below 0.1A (20% of the rated 0.5A) after the fan starts, and this persists for 500ms, it is determined that the rotor is stuck. If a stall fault code 0x20 is triggered, the LED will flash twice. If the heater current instantaneously rises to 3.2A (exceeding 150% of the 2A rated value) due to a short circuit, another Hall current sensor will continuously report an over-limit signal within 200ms. The microcontroller will immediately shut down the PWM output of the MOSFET and set the overcurrent fault code 0x40, causing the LED to flash four times. When any fault occurs, the output of the execution drive module is frozen to prevent the fault from escalating. At the same time, the fault information is uploaded to the substation automation system via the RS-485 bus, realizing a dual protection mechanism of "local closed loop + remote alarm".

[0041] The above process fully demonstrates how the present invention solves the problems of functional fragmentation, non-standard protocols, and delayed response in the prior art by deeply coupling the high-voltage energized state with the temperature control strategy, the standardized application of the Modbus protocol in local closed-loop control, and the synergistic effect of multi-dimensional fault diagnosis, thereby achieving safe, intelligent, and reliable temperature control management in real power distribution scenarios.

[0042] All contents not described in detail in the specification are existing technologies known to those skilled in the art, and the model parameters of each electrical appliance are not specifically limited; conventional equipment can be used. Electrical control components not mentioned in this technical solution are not shown in the figures because they are existing technologies, and will not be described here.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A temperature control system based on a Modbus high-voltage live display, characterized in that: include, The status awareness and communication module collects the energized status signal of the primary equipment and the internal temperature data of the switch cabinet through the high-voltage energized sensor and the temperature sensor, respectively, and encapsulates the data into Modbus RTU frame format and sends it to the main controller through RS-485 bus. The logic linkage control module receives the energized status and temperature value after parsing the Modbus frame, and generates fan start / stop commands and heater power levels according to the preset energized status-temperature control mapping table. The execution drive module receives the fan start / stop command and the heater power level, controls the on / off of the fan motor through a solid-state relay, and controls the power output of the heater through a PWM circuit composed of a MOSFET driver chip and an N-channel MOSFET. The parameter configuration and feedback module responds to the Modbus write request issued by the main controller, performs register-level configuration of temperature control threshold, hysteresis range and linkage mode, and sends the current execution status, temperature reading and equipment power-on flag back to the main controller. The fault diagnosis module monitors temperature sensor disconnection, fan stall, and heater overcurrent signals in real time. When an abnormality is detected, it writes the fault code to the specified address in the Modbus holding register and triggers a local LED alarm light to flash an coded alarm.

2. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: In the state perception and communication module, the high-voltage live sensor adopts a capacitive voltage divider probe. Its input terminal is connected to the primary busbar, and its output terminal is connected to the positive input terminal of the comparator through an isolation amplifier. The negative input terminal of the comparator is connected to an adjustable reference voltage. The comparator output signal is sent to the GPIO pin of the microcontroller after being isolated by an optocoupler. The temperature sensor adopts a PT100 platinum resistance thermometer, which is connected to the constant current source circuit in a two-wire connection method. The voltage sample value is converted by a 24-bit Σ-Δ ADC and then input to the microcontroller. The microcontroller has a built-in Modbus protocol stack that maps GPIO level states to 0x01 or 0x00, converts ADC conversion results to Celsius temperature values ​​according to the IEC 60751 standard, and packages them into Modbus holding register addresses 40001 and 40002. It then drives the RS-485 bus through the RS-485 transceiver in 9600bps, 8N1 format.

3. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: In the logic linkage control module, the microcontroller internally stores a power-state-temperature control mapping table, which contains two sub-tables: when the power-state is 0x01, the start-up temperature threshold is set to 45℃ and the stop temperature to 40℃; when the power-state is 0x00, the start-up temperature threshold is set to 35℃ and the stop temperature to 30℃. The microcontroller reads Modbus input registers 40001 and 40002 every 100ms. If the current temperature is ≥ the start-up threshold and the fan is off, the fan control flag is set; if the current temperature is ≤ the stop temperature and the fan is on, the fan control flag is cleared. The heater power level is divided into four levels: 0%, 30%, 60%, and 100% based on the difference between the temperature and the start-up threshold, and the PWM duty cycle is determined by looking up a table.

4. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: In the execution drive module, the fan control signal is connected to the control terminal of the solid-state relay, and the AC output terminal of the solid-state relay is connected in series in the fan motor power supply circuit; the heater PWM signal is input to the IN pin of the MOSFET driver chip after being optocoupled and isolated, and the HO pin of the MOSFET driver chip drives the gate of the N-channel MOSFET. The drain of the N-channel MOSFET is connected to one end of the heater, and the source is grounded. The other end of the heater is connected to a 24V DC power supply; the PWM frequency is fixed at 10kHz, and the duty cycle is output by the timer channel of the microcontroller.

5. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: In the parameter configuration and feedback module, Modbus holding register address 40010 is used to write the fan start temperature threshold, address 40011 is used to write the stop temperature, and address 40012 is used to write the linkage mode enable flag. The microcontroller scans these registers in each Modbus polling cycle. If a write operation is detected, the internal temperature control parameters are updated. At the same time, the microcontroller writes the current fan status to register 40020, the current duty cycle percentage of the heater to register 40021, and the original value of the energized state to register 40022.

6. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: In the fault diagnosis module, a 10Ω sampling resistor is connected in series in the PT100 circuit. The voltage across the resistor is input to the ADC channel of the microcontroller after passing through a differential amplifier. If the voltage is below 0.1V for 1 second, it is determined that the sensor is disconnected. A Hall current sensor is connected in series in the fan motor power supply circuit. The output voltage is sampled by the ADC. If the current is less than 20% of the rated value after the fan starts and lasts for 500ms, it is determined that the fan is stalled. The heater circuit is also connected to a Hall current sensor. If the current exceeds 150% of the rated value and lasts for 200ms, it is determined that the fan is stalled. The microcontroller encodes disconnection, stall, and overcurrent as 0x10, 0x20, and 0x40 respectively, writes them into the holding register 40030, and controls the LED alarm light to flash the corresponding number of times at a frequency of 1Hz.

7. The temperature control system based on a Modbus high-voltage live display as described in claim 2, characterized in that: The capacitive voltage divider probe of the high-voltage live sensor is installed 5mm directly below the primary busbar inside the switch cabinet and is fixed by epoxy resin potting. Its signal line uses a double-shielded cable, with the inner shielding layer connected to the probe shell and the outer shielding layer connected to the cabinet grounding busbar. The temperature sensor is encapsulated in a stainless steel sheath, and the end of the sheath is welded to a metal bracket near the heating element inside the switch cabinet.

8. The temperature control system based on a Modbus high-voltage live display as described in claim 2, characterized in that: The RS-485 bus adopts a daisy-chain topology, with a 120Ω terminating resistor connected in parallel at the farthest end of the bus. The DE / RE pins of the microcontroller are controlled by the same GPIO, ensuring that the transmit / receive switching timing meets the TTL to RS-485 conversion requirements.

9. The temperature control system based on a Modbus high-voltage live display as described in claim 1, characterized in that: The microcontroller is an STM32F103C8T6, which stores the power-on state-temperature control mapping table and fault coding rules in its internal Flash memory, maintains the current temperature control state machine in SRAM, configures timer TIM2 to PWM output mode, and configures USART1 to Modbus communication interface.

10. The temperature control system based on a Modbus high-voltage live display as described in claim 4, characterized in that: The solid-state relay has an input control voltage of 3.3V, an output withstand voltage of 250VAC, and a rated current of 10A; the N-channel MOSFET has an on-resistance of 0.077Ω, a maximum drain-source voltage of 100V, and the gate drive voltage is provided by the bootstrap circuit of the MOSFET driver chip, with a bootstrap capacitor of 1μF ceramic capacitor.

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