Electrical control system of high-temperature screw machine

Abstract

The utility model relates to the electrical technical field of high-temperature screw machines, in particular to an electrical control system of a high-temperature screw machine, which comprises a controller and a control mainboard of the controller, a PLC (programmable logic controller) communication module, a temperature control module and an integrated power supply module are arranged on the control mainboard, and the PLC communication module is connected with an electronic expansion valve, a pressure switch and a water flow switch. The control mainboard is connected with the high-temperature screw machine through the star-delta electrical assembly, the high-temperature screw machine has high-temperature resistance, high-temperature water with the water outlet temperature reaching up to 120 DEG C is provided and far exceeds the temperature range of a common heat pump water heater, and the use requirement of industrial high-temperature water is met. Through a star-delta starting mode, the starting current is reduced, the starting torque is reduced, and the system can operate more reliably. The electronic expansion valve enables the PID to quickly respond to load changes through efficient system feedback, it is ensured that the evaporation pressure and temperature of the system are maintained within the set range, fluctuation is avoided, and the stability and operation stability of the system are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of high-temperature screw machine electrical systems, in particular to an electrical control system for a high-temperature screw machine. Background Art

[0002] Existing traditional heat pumps typically use refrigerants such as R410A, with water outlet temperatures typically between 55°C and 65°C, suitable for conventional domestic or industrial hot water supply. These heat pumps experience a significant drop in COP (cost-effectiveness ratio) at higher temperatures, resulting in increased energy consumption.

[0003] Traditional screw compressors, when used in high-temperature applications, may face issues with the thermal stability of the lubricating oil at high temperatures, as well as limitations on mechanical efficiency due to the effects of high temperatures. Conventional heat pumps utilize relatively simple control systems, with limited capabilities for precise control of the heating process and fault diagnosis, significantly impacting equipment reliability and stability. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to address the deficiencies of the existing technology and provide a high-temperature screw machine electrical control system that adopts PLC to control the star-delta starting mode, reduces the starting current and the starting torque, and finely controls the opening of the electronic expansion valve by the host control program through the PID algorithm.

[0005] The technical problem to be solved by the present invention is achieved through the following technical solution: an electrical control system for a high-temperature screw compressor, comprising a controller, the controller being equipped with a control mainboard for controlling the unit, the control mainboard being equipped with a preset-coded PLC communication module, a temperature control module, and an integrated power supply module. The PLC communication module of the control mainboard is connected to an electronic expansion valve with automatically adjustable opening, a pressure switch, and a water flow switch provided at the inlet and outlet of the condenser and evaporator. The control mainboard is connected to the high-temperature screw compressor via a star-delta electrical assembly, and the temperature control module is connected to a temperature sensor. Through the control of the PLC module, automated management of the system is achieved, and the operating status of the screw compressor is monitored and adjusted in real time, thereby improving the intelligence level of the system. The opening is automatically adjusted to ensure the stability of the refrigerant flow and pressure, thereby optimizing the cooling effect. By monitoring the system temperature through a precise temperature sensor, the control module can timely adjust the operating status of the equipment to ensure that the equipment operates within the optimal temperature range, thereby improving system efficiency and stability.

[0006] The star-delta electrical assembly includes a star contactor, a delta contactor, a control contactor and a main contactor. The high-temperature screw machine is connected to the three-phase power supply through the main contactor. The star terminal of the high-temperature screw machine is connected to the input terminal of the star contactor to form a Y-type starting mode. The delta terminal of the high-temperature screw machine is connected to the input terminal of the delta contactor to form a Δ-type starting mode. The control contactor is connected to the line between the star contactor and the delta contactor to control the switching between the Y-type starting mode and the Δ-type starting mode. The Y-type starting mode can reduce the starting current in the initial stage and reduce the impact on the power grid. When it is subsequently switched to the Δ-type starting mode, the screw machine can operate stably under full voltage. This starting mode can effectively protect the equipment, reduce the starting current and reduce the starting torque, and the system can operate more reliably.

[0007] As a further feature of this invention, the main contactor is equipped with an overload protection device and an exhaust temperature observer. The overload protection device comprises an overload protection component, a short-circuit protection component, and a phase sequence protection component. The overload protection device effectively prevents motor damage caused by overload, short circuit, or incorrect phase sequence, ensuring long-term, reliable operation of the equipment. The exhaust temperature observer monitors the system's exhaust temperature in real time, preventing excessively high exhaust temperatures from impacting equipment performance and lifespan, thereby further improving the system's protection capabilities and operational efficiency.

[0008] As a further solution of the present invention, the temperature sensor includes an exhaust temperature sensor, a condensing side water inlet temperature sensor, a condensing side water outlet temperature sensor, an evaporating side water inlet temperature sensor, an evaporating side water outlet temperature sensor, a return air temperature sensor, a return air pressure sensor, an oil cooler inlet temperature sensor, and an oil cooler outlet temperature sensor;

[0009] Systematic monitoring is performed on the exhaust gas temperature, condenser water inlet temperature, condenser water outlet temperature, evaporator water inlet temperature, evaporator water outlet temperature, return air temperature, return air pressure, oil cooler inlet temperature, and oil cooler outlet temperature. This combination of sensors enables the system to acquire real-time information on each key parameter for comprehensive monitoring. The data provided by each sensor is used to adjust system parameters in real time to maintain optimal equipment operating conditions. This allows for the timely identification of potential issues and prevents system failures and damage. Effective parameter management reduces damage to equipment from overloads and overheating, improving fault prevention capabilities. This ensures efficient system operation, reduces energy consumption, and extends equipment life. This enhances the system's intelligent management capabilities and strengthens equipment safety, stability, and energy efficiency.

[0010] As a further solution of the present invention, the temperature sensor adopts a resistance temperature sensor, the temperature collection range is -200°C to +200°C, the display accuracy is 0.1°C, and the comprehensive accuracy is 0.3°C.

[0011] As a further feature of this invention, the pressure switch includes a high-pressure switch, a low-pressure switch, and a linkage switch. These switches work together to control the start and stop of the unit. The high-pressure and low-pressure switches prevent system damage due to excessively high or low pressure, ensuring equipment operation within a safe range. By precisely controlling the start and stop of the unit, the system operates in optimal conditions, improving energy efficiency. The linkage switch prevents a single failure from causing a complete system shutdown, enhancing system stability.

[0012] As a further feature of this utility model, the electronic expansion valve opening is calculated and controlled by the host control program using a PID algorithm, adjusting the electronic expansion valve opening between 0% and 100%. The PID algorithm precisely adjusts the valve opening based on real-time feedback, ensuring that system temperature and pressure remain within the set range. This effectively reduces system fluctuations, improving system stability and operational smoothness. Through precise control, system energy efficiency is improved and energy consumption is reduced. PID control provides rapid response, enabling timely adjustments to address load changes and improving system performance.

[0013] As a further solution of the present invention, the water flow switch includes a chilled water flow switch provided at the inlet and outlet of the condenser and a cooling water flow switch provided at the inlet and outlet of the evaporator. The chilled water flow switch and the cooling water flow switch are made of stainless steel that can withstand a high-temperature water environment of 120 degrees Celsius. The chilled water flow switch and the cooling water flow switch monitor the water flow of the condenser and the evaporator to ensure that the system operates within the normal flow range and prevent the equipment from overheating or being damaged due to insufficient flow. By real-time monitoring and feedback of the water flow status, the system operation can be adjusted in a timely manner to maintain the stability and reliability of the system. The use of stainless steel that can withstand a high-temperature water environment of 120 degrees Celsius ensures the long-term stability and reliability of the switch under high-temperature conditions, avoids material aging or failure, improves the durability and service life of the switch, and thus reduces the maintenance frequency and cost. These effects comprehensively improve the operational safety, stability and long-term reliability of the system.

[0014] The beneficial effects of the utility model are:

[0015] The utility model provides an electrical control system for a high-temperature screw machine, which uses a high-temperature screw machine with high-temperature resistance and higher efficiency. It provides high-temperature water with an outlet temperature of up to 120°C, which far exceeds the temperature range of general heat pump water heaters, and opens up the possibility of industrial high-temperature water use, such as special process or high-temperature disinfection and other higher temperature applications. Through the star-delta starting method, the starting current and starting torque are reduced, making the system more reliable. The electronic expansion valve can accurately adjust the valve opening according to real-time feedback through the PID algorithm. Through efficient system feedback, the PID can respond quickly to load changes, ensuring that the system evaporation pressure and temperature are maintained within the set range to avoid large fluctuations. Effectively reduce system fluctuations and improve system stability and smooth operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the electrical wiring of the high-temperature screw machine of the present utility model;

[0017] Figure 2 This is a schematic diagram of the controller of the present utility model;

[0018] Figure 3 This is a schematic diagram of the MOP forced control logic of the utility model.

[0019] Among them: 1-PLC communication module, 101-electronic expansion valve, 102-pressure switch, 103-water flow switch, 2-temperature control module, 201-temperature sensor, 3-integrated power supply module, 4-high-temperature screw machine, 401-main contactor, 411-overload protection device, 412-exhaust temperature observer 402-delta contactor, 403-control contactor, 404-star contactor. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings). In the description of the present utility model, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model.

[0022] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0023] Example 1

[0024] like Figures 1 to 2 The electrical control system for a high-temperature screw compressor is shown in Figure 1. It includes a controller with a control board for the unit. The controller uses a Siemens S7-200SMART as the main control unit and AE08, AR04, and DR08 modules as input and output expansion points. The control panel uses a Kunlun Tongtai 15-inch TPC1570gi model.

[0025] The control mainboard is equipped with a PLC communication module 1 with a preset code, a temperature control module 2, and an integrated power supply module 3. The PLC communication module of the control mainboard is connected to an electronic expansion valve 101 that can automatically adjust the opening, a pressure switch 102, and a water flow switch 103 set at the inlet and outlet of the condenser and evaporator.

[0026] The opening of the electronic expansion valve 101 is calculated and controlled by the control program on the mainboard using a PID algorithm, adjusting the opening between 0% and 100%. The PID algorithm precisely adjusts the valve opening based on real-time feedback. The electronic expansion valve controls the evaporator liquid level in flooded evaporators, ensuring that system temperature and pressure remain within the set range. The opening of the electronic expansion valve 101 is calculated and controlled by the host control program using a PID algorithm, adjusting the opening between 0% and 100%. This effectively reduces system fluctuations and improves system stability and smooth operation.

[0027] The opening degree of the electronic expansion valve is defined by the following formula:

[0028] u(t)=K[e(t)+(1 / Ti)∫e(t)dt+Td(de(t) / dt)];

[0029] u(t) electronic expansion valve opening;

[0030] e(t) is the difference between the current liquid level and the set target liquid level;

[0031] K proportional gain;

[0032] Ti integration time;

[0033] Td derivative time;

[0034] The relevant control parameter settings of the electronic expansion valve are shown in the parameter table. Its PID setting parameters are:

[0035] parameter default value Minimum Maximum unit Remark Liquid level 95 0 300 mm K proportional gain 0.4 0 1000 -- Ti integration time 360 0 1000 s <![CDATA[ Td Derivative Time]]> 0 0 1000 s Step rate 250 150 300 steps / second Control Hold Zone Deviation Target tab 1 0 5 mm Total number of expansion valve steps 3810 -- -- step According to valve body setting Minimum opening of electronic expansion valve 0 0 10 ％ Maximum opening of electronic expansion valve 100 50 100 ％ Compressor shutdown delay time 15 0 60 S Start pre-opening 30 0 100 ％ Start pre-opening delay 30 0 300 S MOP setpoint 3.5 3 6 bar <![CDATA[MOP control range( PCR )]]> 0.5 0.1 2 bar

[0036] like Figure 3 As shown, the MOP forced control logic is as follows: MOP is the set MOP value, Pe is the collected low pressure value, Pcr is the MOP control range, and M is the valve action step number, with positive indicating increase and negative indicating decrease. When MOP>Pe>MOP-Pcr, then M≤0 (i.e., when the PID calculated action step number M<0, the action is based on the calculated value. If the PID calculated action step number M≥0, then M=0). When Pe≥MOP, M≤-50 (i.e., when the PID calculated action step number M<-50, the action is based on the calculated value. If the calculated value M≥-50, then M=-50). The detection period is t (settable to 6 seconds). When Pe≤MOP-Pcr, control is based on normal control logic. This function is effective after the compressor is running and is not enabled during the startup phase. The expansion valve completes fine control adjustment.

[0037] The pressure switch 102 includes a high-pressure switch, a low-pressure switch, and a linkage switch. These switches work together to control the start and stop of the unit. The high-pressure and low-pressure switches activate when the system pressure is too high or too low, precisely controlling the start and stop of the unit and ensuring optimal system operation. If a single system fault occurs, the linkage switch activates, preventing a complete system shutdown and maintaining stable system operation.

[0038] The water flow switches 103 include chilled water flow switches at the condenser inlet and outlet, and cooling water flow switches at the evaporator inlet and outlet. Based on the water flow rate, the chilled water flow switch is selected to meet the water flow requirement of 98m³ / h or above, and the cooling water flow switch is selected to meet the water flow requirement of 18m³ / h or above. These switches are turned on within this range. The chilled water flow switches and cooling water flow switches monitor and provide real-time feedback on the condenser and evaporator water flow and flow status, ensuring the system operates within the normal flow range and preventing equipment overheating or damage due to insufficient flow.

[0039] The chilled water flow switch and cooling water flow switch are made of stainless steel that can withstand high temperature water environments up to 120 degrees Celsius. Made of stainless steel that can withstand high temperature water environments up to 120 degrees Celsius, the stainless steel chilled water flow switch and cooling water flow switch can be used in high temperature working conditions.

[0040] The control motherboard is connected to a high-temperature screw compressor 4 via a star-delta electrical assembly. The high-temperature screw compressor uses a Hanbell RC2-T compressor. The star-delta electrical assembly includes a star contactor (KM3) 404, a delta contactor (KM2) 402, a control contactor (KM1) 403, and a main contactor 401. The star contactor is a Y contactor, and the delta contactor is a Δ contactor. The star contactor uses the Schneider LC1-D245 model, and the main contactor uses the LC1-D410 model.

[0041] The high-temperature screw machine 4 is connected to the three-phase power supply through the main contactor. The star terminal of the high-temperature screw machine 4 is connected to the input terminal of the star contactor to form a Y-type starting mode. The delta terminal of the high-temperature screw machine 4 is connected to the input terminal of the delta contactor to form a Δ-type starting mode. The control contactor is connected to the line between the star contactor and the delta contactor to control the switching between the Y-type starting mode and the Δ-type starting mode, forming a Y-Δ connection starting mode.

[0042] When selecting the main contactor, refer to the maximum current and substitute it into the formula for calculation. Main contactor current = maximum current / 1.732 * 1.2. Star contactor current = main contactor current * 2 / 3. The Y-Δ connection starting method uses a Y connection at startup. At this time, the voltage on the winding is reduced to 1 / 3 of the input voltage. After startup is complete, it is reconnected to a Δ connection. After the Y-connection start, 0.25 seconds after the Δ connection conversion is completed, the star contactor (KM3) 1 is energized and operates. Within 0.25 seconds, improper contactor operation may cause a false short circuit, causing the compressor to trip. The PLC signal delay control delays the power supply time of the KM2 and KM3 coils by 0.3 seconds. This is used to protect the compressor.

[0043] High-temperature screw compressors have six connection points: Z, X, Y, U, V, and W. When connected in a Y-shape, KM1 and KM3 are energized, bringing Z, X, and Y together to form the center of the Y-shape. After 3 seconds, KM1 and KM3 are disconnected. Approximately 0.25 seconds later, KM1 and KM2 are energized, transforming the system into a Δ-shape connection. This starting method, also known as reduced-voltage starting, reduces starting current by lowering the starting voltage. This reduction in starting current and torque ensures reliable system operation.

[0044] The main contactor 401 is equipped with an overload protection device 411 and an exhaust temperature observer 412. The overload protection device includes an overload protection component, a short-circuit protection component, and a phase sequence protection component. The overload protection device prevents damage to the motor due to overload, short circuit, or incorrect phase sequence, ensuring long-term and reliable operation of the equipment.

[0045] The exhaust temperature observer monitors the exhaust temperature of the system in real time. When the exhaust temperature is too high, the exhaust temperature of the system is promptly controlled to be within the specified range, thereby improving the protection capability and operation efficiency of the system.

[0046] The temperature control module 2 is connected to a temperature sensor 201; the temperature sensor includes an exhaust temperature sensor, a condensing side water inlet temperature sensor, a condensing side water outlet temperature sensor, an evaporating side water inlet temperature sensor, an evaporating side water outlet temperature sensor, a return air temperature sensor, a return air pressure sensor, an oil cooler inlet temperature, and an oil cooler outlet temperature sensor; the temperature sensor adopts a resistance temperature sensor, and the acquisition temperature range of the PT100 resistance temperature sensor is -200℃ to +200℃, the display accuracy is 0.1℃, and the comprehensive accuracy is 0.3℃.

[0047] Temperature sensors monitor exhaust temperature, condenser water inlet and outlet temperatures, evaporator water inlet and outlet temperatures, return air temperature, return air pressure, oil cooler inlet and outlet temperatures. This combination of sensors enables the system to acquire real-time information on key parameters, enabling comprehensive monitoring and real-time adjustment of system parameters to maintain optimal equipment operation, identify potential issues promptly, and prevent system failures and damage.

[0048] The entire system is controlled by a PLC module, enabling automated management and real-time monitoring and adjustment of the operating status of screw compressor 1, enhancing the system's intelligence. The opening of electronic expansion valve 101 is calculated and controlled by the control program on the control board using a PID algorithm, automatically adjusting the opening to maintain stable refrigerant flow and pressure. Precise temperature sensors monitor the system's temperature, allowing the control module to promptly adjust the device's operating status to ensure operation within the optimal temperature range, thereby improving system efficiency and stability.

[0049] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high-temperature screw machine electrical control system, characterized in that: The invention comprises a controller, wherein the controller is provided with a control mainboard for controlling the unit, the control mainboard is provided with a PLC communication module (1) with a preset code, a temperature control module (2), and an integrated power supply module (3), the PLC communication module of the control mainboard is connected to an electronic expansion valve (101) capable of automatically adjusting the opening, a pressure switch (102), and a water flow switch (103) provided at the inlet and outlet of a condenser and an evaporator, the control mainboard is connected to a high-temperature screw machine (4) via a star-delta electrical component, and the temperature control module (2) is connected to a temperature sensor (201); The star-delta electrical assembly comprises a star contactor (404), a delta contactor (402), a control contactor (403) and a main contactor (401); the high-temperature screw machine is connected to a three-phase power supply via the main contactor; the star connection terminal of the high-temperature screw machine is connected to the input terminal of the star contactor to form a Y-type starting mode; the delta connection terminal of the high-temperature screw machine is connected to the input terminal of the delta contactor to form a Δ-type starting mode; the control contactor is connected to the line between the star contactor and the delta contactor to control the switching between the Y-type starting mode and the Δ-type starting mode.

2. The electrical control system for a high-temperature screw machine according to claim 1, characterized in that: The main contactor (401) is provided with an overload protection device (411) and an exhaust temperature observer (412), and the overload protection device comprises an overload protection component, a short circuit protection component, and a phase sequence protection component.

3. The electrical control system for a high-temperature screw machine according to claim 1, characterized in that: The temperature sensor (201) includes an exhaust temperature sensor, a condensation side water inlet temperature sensor, a condensation side water outlet temperature sensor, an evaporation side water inlet temperature sensor, an evaporation side water outlet temperature sensor, a return air temperature sensor, a return air pressure sensor, an oil cooler inlet temperature sensor, and an oil cooler outlet temperature sensor; The external exhaust temperature, condensation side water inlet temperature, condensation side water outlet temperature, evaporation side water inlet temperature, evaporation side water outlet temperature, return air temperature, return air pressure, oil cooler inlet temperature, and oil cooler outlet temperature are systematically tested.

4. The electrical control system for a high-temperature screw machine according to claim 3, characterized in that: The temperature sensor (201) adopts a resistance temperature sensor, and the temperature collection range is -200°C to +200°C, the display accuracy is 0.1°C, and the comprehensive accuracy is 0.3°C.

5. The electrical control system for a high-temperature screw machine according to claim 1, characterized in that: The pressure switch (102) comprises a high-pressure switch, a low-pressure switch and a linkage switch, and the high-pressure switch, the low-pressure switch and the linkage switch cooperate to control the start and stop of the unit.

6. The electrical control system for a high-temperature screw compressor according to claim 1, characterized in that: The opening of the electronic expansion valve (101) is calculated and controlled by a host control program through a PID algorithm, and the opening of the electronic expansion valve is controlled to be adjusted between 0% and 100%.

7. The electrical control system for a high-temperature screw compressor according to claim 1, characterized in that: The water flow switch (103) comprises a chilled water flow switch arranged at the inlet and outlet of the condenser and a cooling water flow switch arranged at the inlet and outlet of the evaporator. The chilled water flow switch and the cooling water flow switch are made of stainless steel material that can withstand a high-temperature water environment of 120 degrees Celsius.

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