Multi-system low-temperature cold and hot water machine control method

Abstract

The invention relates to a multi-system low-temperature cold and hot water machine control method, in particular to a multi-system low-temperature cold and hot water machine control method. According to the control method, efficient, reliable and energy-saving operation of the multi-system cold and hot water machine is achieved through modular design, mode switching and dynamic parameter adjustment.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat pump system control, and particularly relates to a control method for a multi-system low-temperature cold and hot water machine. Background Art

[0002] With the increasing demand for cold and hot water in the industrial and commercial fields, low-temperature cold and hot water machines, as an efficient heat management device, are widely used in scenarios such as hotels, hospitals, factories, and data centers. However, traditional cold and hot water machines face many challenges in practical applications: Poor load adaptability: The single-system design is difficult to cope with the fluctuations of peak and valley loads, resulting in waste of resources or insufficient supply; Low energy efficiency ratio: The fixed operation mode cannot be dynamically adjusted according to parameters such as ambient temperature and inlet water temperature, resulting in high energy consumption; Insufficient control accuracy: The temperature fluctuation range is large, making it difficult to meet the requirements of precision temperature control scenarios; Low defrosting efficiency: In low-temperature environments, traditional defrosting mechanisms are frequently triggered, affecting system stability and increasing energy consumption; High operation and maintenance costs: Frequent startup and shutdown of equipment and non-intelligent mode switching lead to increased mechanical wear and shortened service life. To solve the above problems, the industry has proposed technical directions such as multi-system collaborative control, intelligent mode switching, and dynamic parameter optimization. For example, elastic load distribution is achieved through multi-system combination (such as single / double / four systems), the energy efficiency ratio is improved by dynamically adjusting the fan speed and compressor frequency, and an adaptive defrosting algorithm is introduced to reduce ineffective energy consumption. However, the existing technologies still have the following deficiencies: The multi-system collaborative control lacks flexibility and is difficult to dynamically adjust according to real-time requirements; The mode switching logic is complex and cannot be efficiently scheduled when there are conflicts between cold and hot demands; The defrosting mechanism depends on fixed parameters and cannot adapt to changing environmental conditions. Therefore, there is an urgent need for an efficient, flexible, and intelligent control method for multi-system low-temperature cold and hot water machines to solve the limitations of traditional technologies and meet the efficient, stable, and energy-saving requirements for cold and hot water supply in modern industrial and commercial fields. Summary of the Invention

[0003] To at least solve one of the above problems existing in the prior art, the present invention provides a control method for a multi-system low-temperature cold and hot water machine.

[0004] The object of the present invention can be achieved by the following technical solutions:

[0005] A control method for a multi-system low-temperature cold and hot water machine, which is applied to a low-temperature cold and hot water machine provided with a four-heat pump system and a double air duct. The four-heat pump system includes a first heat pump, a second heat pump, a third heat pump, and a fourth heat pump connected in parallel. The double air duct includes a first air duct connected to the first heat pump and the second heat pump, and a second air duct connected to the third heat pump and the fourth heat pump. A first fan is arranged in the first air duct, and a second fan is arranged in the second air duct. The outer coils connected to the first heat pump and the outer coils connected to the second heat pump are arranged in the first air duct and exchange heat with the outside through the first air duct. The outer coils connected to the third heat pump and the outer coils connected to the fourth heat pump are arranged in the second air duct and exchange heat with the outside through the second air duct;

[0006] Among them, the working modes of the system include single-system operation, double-system operation, and four-system operation. When the user selects single-system operation, the cold and hot water machine operates with a single air duct. When the user selects double-system operation, the cold and hot water machine adjusts to operate with a single air duct or a double air duct according to the user's selection. When the user selects four-system operation, the cold and hot water machine operates with a double air duct.

[0007] In a further embodiment of the present invention, when the air duct control is a single air duct, when the system operates, the fan is turned on first, and after a first period of time, the compressor is turned on. When the system shuts down, the compressor is turned off first, and after a second period of time, the fan is turned off. The system adjusts the speed of the fan according to the ambient temperature.

[0008] In a further embodiment of the present invention, when the air duct control is a single air duct and the system is in double-system operation, the system adjusts the speed of the fan according to the ambient temperature and the inlet water temperature.

[0009] In a further embodiment of the present invention, when the air duct control is a single air duct and the system is in double-system operation, the wind speed of the fan is as follows:

[0010] When the system is in heating mode, when the temperature is less than the first temperature or the inlet water temperature is less than the second temperature, the fan runs at high speed; when the ambient temperature is greater than the third temperature and the inlet water temperature is greater than the fourth temperature, the fan runs at low speed; when the ambient temperature is greater than the third temperature and the inlet water temperature is less than the second temperature, the fan runs at high speed; when the ambient temperature is not less than the first temperature and not greater than the third temperature or the purified water temperature is not less than the second temperature and not greater than the fourth temperature, the fan runs at low speed;

[0011] When the system is in cooling mode, when the ambient temperature is greater than the fifth temperature, the fan runs at high speed; when the ambient temperature is less than the sixth temperature, the fan runs at low speed; when the ambient temperature is not less than the sixth temperature and not greater than the fifth temperature, the fan maintains its original operating speed.

[0012] In a further embodiment of the present invention, when the air duct control is a dual air duct, the system controls the fan speed according to the compressor operating frequency, the ambient temperature, and the temperature of the external coil;

[0013] Wherein, if both coils in a single air duct are operating, then when the system is in heating mode, the lower of the two temperatures is taken for judgment; when the system is in cooling mode, the higher of the two temperatures is taken for judgment.

[0014] In a further embodiment of the present invention, a defrost mode is further included,

[0015] When the ambient temperature is greater than a preset extended defrost ambient temperature and the system simultaneously meets Condition 101 and Condition 102, the system enters the defrost mode;

[0016] When the ambient temperature is not greater than the preset extended defrost ambient temperature and the system simultaneously meets Condition 101, Condition 102, and Condition 103 or the system simultaneously meets Condition 101, Condition 102, and Condition 104, the system enters the defrost mode;

[0017] Wherein:

[0018] Condition 101: The compressor has accumulated operation for the sum of the third time, the adaptive time, and the constant temperature compensation time, and the compressor has continuously operated for the fourth time;

[0019] Condition 102: The temperature of the external coil is not greater than the seventh temperature for more than the fifth time;

[0020] Condition 103: The difference between the ambient temperature and the temperature of the external coil is not less than the eighth temperature;

[0021] Condition 104: The compressor has accumulated operation for the sum of the sixth time, the adaptive time, and the constant temperature compensation time, and the compressor has continuously operated for the fourth time.

[0022] In a further embodiment of the present invention, when the system is in the defrost mode and meets any one of Condition 201, Condition 202, and Condition 203, the defrost mode is exited;

[0023] Wherein:

[0024] Condition 201: The temperature of the external coil is greater than the ninth temperature;

[0025] Condition 202: The defrost time reaches the seventh time;

[0026] Condition 203: The outlet water temperature is not greater than the tenth temperature and lasts for the eighth time.

[0027] In a further embodiment of the present invention, the adaptive time is adjusted according to the defrost duration of each time of the system;

[0028] When the defrosting duration of the system is less than the ninth time, the adaptive time increases by the eleventh time;

[0029] When the defrosting duration of the system is not less than the ninth time and less than the tenth time, the adaptive time remains unchanged;

[0030] When the defrosting duration of the system is not less than the tenth time, the adaptive time decreases by the eleventh time.

[0031] In a further embodiment of the present invention, after the system enters the defrosting mode, the compressor and the fan are turned off, the four-way valve and the electric heater are started after a delay of the twelfth time, and the compressor is restarted at the operating frequency of the first frequency after a delay of the thirteenth time.

[0032] In a further embodiment of the present invention, after the system exits the defrosting mode, the compressor is turned off, the four-way valve and the electric heater are turned off after a delay of the fourteenth time, the fan is restarted after a delay of the fifteenth time, and the compressor operation is resumed after the sixteenth time. At the same time, the cumulative operation time of the compressor is cleared.

[0033] The beneficial effects of the present invention are as follows: Through modular design, mode switching, and dynamic parameter adjustment, the control method realizes the efficient, reliable, and energy-saving operation of the multi-system cold and hot water machine. Brief Description of the Drawings

[0034] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

[0035] Figure 1 It is a schematic structural diagram of a multi-system cold and hot water machine provided in an embodiment of the present invention;

[0036] Figure 2 It is a schematic structural diagram of a double-air duct provided in an embodiment of the present invention;

[0037] Figure 3 It is a schematic structural diagram of a single heat pump system provided in an embodiment of the present invention;

[0038] Figure 4 It is a partial circuit diagram of the system high and low pressure sensor ports provided in an embodiment of the present invention;

[0039] Figure 5 It is a partial circuit diagram of the system main control module provided in an embodiment of the present invention;

[0040] Figure 6 It is a partial circuit diagram of the system provided in an embodiment of the present invention;

[0041] Figure 7 It is a partial circuit diagram of the system relay electronic expansion valve provided in an embodiment of the present invention.

[0042] Reference numerals: 1, compressor; 2, four-way valve; 3, condenser; 4, gas-liquid separator; 5, evaporator; 6, fan; 7, dryer filter; 8, liquid receiver; 9, economizer; 10, main circuit expansion valve; 11, liquid injection solenoid valve; 12, auxiliary circuit expansion valve; 13, liquid injection check valve; 14, bypass valve; 15, high pressure switch; 16, low pressure switch; 17, needle valve; 18, suction temperature sensor; 19, discharge temperature sensor; 20, outer coil temperature sensor; 21, liquid injection inlet temperature sensor; 22, liquid injection outlet temperature sensor; 23, suction pressure sensor. Detailed implementation manners

[0043] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, describe in detail the specific implementation manners, structures, features and effects of the present invention.

[0044] Please refer to Figure 1-3 , in an embodiment of the present invention, a control method for a multi-system cold and hot water machine is provided, which is applied to a low-temperature cold and hot water machine provided with a four-heat pump system and two air ducts. The four-heat pump system includes a first heat pump, a second heat pump, a third heat pump and a fourth heat pump arranged in parallel. The two air ducts include a first air duct connected to the first heat pump and the second heat pump and a second air duct connected to the third heat pump and the fourth heat pump. A first fan is arranged in the first air duct, and a second fan is arranged in the second air duct. The method includes the following steps:

[0045] Step S101: Select a working system;

[0046] Step S102: Select a working mode;

[0047] Step S103: Monitor the system operation parameters and adjust the operating states of the devices in the system;

[0048] Among them, in step S101, the working systems include single-system working, dual-system working and four-system working; step S103 includes fan control, and the fan control is divided into single air duct and dual air duct. When the user selects single-system working, the fan control corresponds to the single air duct. When the user selects dual-system working, the fan control adjusts to the single air duct or the dual air duct according to the user's selection. When the user selects four-system working, the fan control corresponds to the dual air duct. For the specific structure, please refer to Figure 1-2 . Figure 1 A connection relationship between the four systems and the two air ducts of the cold and hot water machine is provided, Figure 2 A connection relationship of the devices within a single system is provided.

[0049] When the user selects single-system operation, any one of the first heat pump, the second heat pump, the third heat pump, or the fourth heat pump can be selected for operation. When operating in single-system mode, the air duct connected to this system operates synchronously. That is, there are four operating modes: the first heat pump and the first air duct operate, or the second heat pump and the first air duct operate, or the third heat pump and the second air duct operate, or the fourth heat pump and the second air duct operate, thus realizing single-fan and single-air-duct operation. When the user selects dual-system and single-air-duct operation, there are two operating modes available: the first heat pump, the second heat pump, and the first air duct operate, or the third heat pump, the fourth heat pump, and the second air duct operate. When the user selects dual-system and dual-air-duct operation, there are four operating modes for the user to choose from: the first heat pump, the third heat pump, and the dual air ducts operate, or the first heat pump, the third heat pump, and the dual air ducts operate, or the second heat pump, the third heat pump, and the dual air ducts operate, or the second heat pump, the fourth heat pump, and the dual air ducts operate. When the user selects four-system operation, the system simultaneously operates the first heat pump, the second heat pump, the third heat pump, the fourth heat pump, the first air duct, and the second air duct.

[0050] From this, it can be seen that the user can make the heat pump have multiple different operating modes by selecting different heat pumps and different air ducts. At the same time, the functions of the cold and hot water machine can be further improved by setting the first heat pump, the second heat pump, the third heat pump, and the fourth heat pump as different types of heat pumps.

[0051] In step S102, the operating modes include a heating mode, a cooling mode, and a hot water mode.

[0052] In step S103, the monitored operating parameters include the inlet water temperature, the temperature of the outer coil, and the operating time of compressor 1. The equipment adjusted within the system includes: compressor 1, expansion valve, fan, and water pump.

[0053] In this embodiment, the cold and hot water machine composed of multiple systems can start the corresponding number of systems according to the customer's selection to meet the user's needs. The user can select the system configuration according to the actual usage requirements. During low-load periods, the user can only start System 1 and operate with a single air duct. During medium-load periods, the user can choose to start System 1 and System 2 and dynamically switch between single / dual air ducts according to the operating frequency of compressor 1. During high-load periods, the user can choose to fully open all four systems, and the system forcibly starts dual-air-duct cooling to ensure stable operation of the system under high loads.

[0054] Please refer to Figure 3, in some embodiments, the first port of the compressor 1 is successively connected to the first port of the four-way valve 2 through an exhaust temperature sensor 19, a high-pressure switch 15, and a needle valve 17. The second port of the four-way valve 2 is connected to the first port of the condenser 3. The condenser 3 exchanges heat with water and heats or cools the water. The second port of the condenser 3 is connected to the first port of the liquid receiver 8 through a dryer filter 7. The second port of the liquid receiver 8 is respectively connected to the first port of the economizer 9 and the first port of the liquid injection solenoid valve 11. The second port of the liquid injection solenoid valve 11 is successively connected to the fourth port of the economizer 9 through a bypass expansion valve 12 and a liquid injection inlet temperature sensor 21. The second port of the economizer 9 is successively connected to the second port of the compressor 1 through a liquid injection outlet temperature sensor 22 and a liquid injection check valve 13. The flow direction of the check valve 13 is from the second port of the economizer 9 to the second port of the compressor. The third port of the economizer 9 is respectively connected to the first port of the main expansion valve 10 and the first port of the unloading valve 14. The second ports of the main expansion valve 10 and the unloading valve 14 are both connected to the first port of the dryer filter 7. The second port of the dryer filter 7 is connected to the first port of the evaporator 5. The second port of the evaporator 5 is connected to the third port of the four-way valve 2. The evaporator 5 is used to exchange heat with the outside air. An external coil temperature sensor 20 is provided on the evaporator 5. A blower 6 is further provided outside the evaporator 5 to increase the air volume passing through the evaporator 5. The fourth port of the four-way valve 2 is connected to the first port of the gas-liquid separator 4 through a needle valve 17. The second port of the gas-liquid separator 4 is successively connected to the third port of the compressor 1 through a suction pressure sensor 23, a low-pressure switch 16, and a suction temperature sensor 18.

[0055] In a further embodiment of the present invention, the control of the load in step S103 in different working modes is as follows:

[0056] Heating mode: When the inlet water temperature is not greater than the difference between the preset heating set temperature and the preset deadband temperature, the control system performs heating work; when the inlet water temperature is not less than the preset heating set temperature, the control system stops heating work;

[0057] Cooling mode: When the inlet water temperature is not less than the sum of the preset cooling set temperature and the preset deadband temperature, the control system performs cooling work; when the inlet water temperature is not greater than the preset cooling set temperature, the control system stops cooling work;

[0058] Hot water mode: When the water tank temperature is not greater than the difference between the preset hot water set temperature and the preset deadband temperature, the control system performs hot water work; when the water tank temperature is not less than the preset hot water set temperature, the control system stops hot water work.

[0059] In this embodiment, the system controls the operation of the device according to the working mode selected by the user and the inlet water temperature. At the same time, a dead-band temperature is also set to prevent the system from frequently starting and stopping the device when the inlet water temperature is near the target temperature preset by the user, which can effectively reduce mechanical wear.

[0060] Among them, the compressor 1 is also provided with a 3-minute protection, that is, after the compressor 1 shuts down, it must be at least 3 minutes before it can be started (there is no 3-minute protection for the first power-on); before the system operates in the heating or cooling mode, the circulating water pump starts 90s before the compressor 1; when the system requests to shut down, the circulating water pump closes 90s after the compressor 1 stops.

[0061] In a further embodiment of the present invention, the working frequencies of the compressors used in various modes are divided into 10 gears F1 - F20. For details, please refer to Table 1 below. During defrosting, the frequency of the compressor 1 is 70Hz. After the compressor 1 starts, in the first 60 seconds before the first frequency, it runs to 50Hz and then runs at the target frequency. At the same time, after the frequency of the compressor 1 is greater than 50Hz after starting, it can only increase by 10Hz every at least 60S.

[0062] Table 1: Compressor 1 Working Frequency Gear Comparison Table

[0063] Gear F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 Hz 90 88 85 82 80 78 75 72 70 68 Gear F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 Hz 40 45 55 60 65 70 75 80 85 90

[0064] When the system is in the heating mode and the hot water mode, the working gear of the compressor 1 is determined by the ambient temperature and the inlet water temperature. Among them, when the system is in the hot water mode, the inlet water temperature is the water tank temperature. For details, please refer to Table 2.

[0065] Table 2: Compressor 1 Working Gear Selection Comparison Table during Heating

[0066]

[0067] When the system is in the cooling mode, the working gear of the compressor 1 is controlled according to the ambient temperature and the inlet water temperature. For details, please refer to Table 3.

[0068] Table 3: Compressor 1 Working Gear Selection Comparison Table during Cooling

[0069]

[0070] In a further embodiment of the present invention, the system is also provided with constant temperature control. When the user selects the four-system operation, the No. 1 press, the No. 2 press and the blower 1 form a group, and the No. 3 press, the No. 4 press and the blower 2 form a second group; when the user selects the dual-system operation, the No. 1 press, the No. 2 press and the blower form a group. When the system is heating, when the water temperature reaches the difference between the set temperature and 2 (when refrigerating, it is the sum of the set temperature and 2), the frequency targets of the two groups are adjusted to 60 Hz and start to enter. The press frequency enters constant temperature frequency modulation. The two groups of presses are processed according to the constant temperature logic of starting the first group first. The second group is turned on and maintained. When the first group turned on is adjusted to the lowest operating frequency of 40 Hz, this group is turned off and the corresponding blower also needs to be turned off. Then the second group turned on enters the constant temperature control logic.

[0071] Among them, the constant temperature control logic is:

[0072] Heating: When the set temperature - 2 < the inlet water temperature < the set temperature, if the temperature does not rise, the frequency is increased by 1 Hz every 30S; when the set temperature < the inlet water temperature < the set temperature + 2, if the temperature does not fall, the frequency is decreased by 1 Hz every 30S; when the inlet water temperature = the set temperature, the current frequency is maintained; when the inlet water temperature ≥ the set temperature + 2, constant temperature shutdown; when the inlet water temperature ≤ the set temperature - 4, exit constant temperature control.

[0073] Refrigeration: When the set temperature - 2 < the inlet water temperature < the set temperature, if the temperature does not rise, the frequency is increased by 1 Hz every 30S; when the set temperature < the inlet water temperature < the set temperature + 2, if the temperature does not fall, the frequency is decreased by 1 Hz every 30S; when the inlet water temperature = the set temperature, the current frequency is maintained; when the inlet water temperature ≥ the set temperature + 2, constant temperature shutdown; when the inlet water temperature ≤ the set temperature - 4, exit constant temperature control.

[0074] In a further embodiment of the present invention, the working modes also include: refrigeration and hot water mode, and heating and hot water mode; when the working mode is refrigeration and hot water mode, the hot water operation is preferentially run, and the heating operation runs when the hot water operation stops; when the working mode is heating and hot water mode, the hot water operation is preferentially run, and the refrigeration operation runs when the hot water operation stops.

[0075] In a further embodiment of the present invention, when the air duct control is a single air duct, when the system operates, the blower is first turned on, and the compressor 1 is turned on after the first time. When the system shuts down, the compressor 1 is first turned off, and the blower is turned off after the second time. The speed of the blower is adjusted according to the ambient temperature.

[0076] In this embodiment, when the system is turned on, the blower is turned on 10 seconds before the press; when the system is turned off, the blower is turned off 90 seconds after the press; when the system is in the defrosting mode, the blower stops running at the same time.

[0077] In a further embodiment of the present invention, when the air duct control is a single air duct and the system is in dual-system operation, the air speed of the blower is:

[0078] When the system is in the heating mode, when the temperature is less than 25°C or the inlet water temperature is less than 43°C, the fan runs at high speed; when the ambient temperature is greater than 26°C and the inlet water temperature is greater than 45°C, the fan runs at low speed; when the ambient temperature is greater than 26°C and the inlet water temperature is less than 43°C, the fan runs at high speed; when the ambient temperature is not less than 25°C and not greater than 26°C or the purified water temperature is not less than 43°C and not greater than 45°C, the fan runs at low speed;

[0079] When the system is in the cooling mode, when the ambient temperature is greater than 30°C, the fan runs at high speed; when the ambient temperature is less than 29°C, the fan runs at low speed; when the ambient temperature is not less than 29°C and not greater than 30°C, the fan operates at the original running speed.

[0080] Please refer to Table 4 and Table 5. In a further embodiment of the present invention, when the air duct control is a dual air duct, the wind speed of the fan is determined according to the operating frequency of the compressor 1, the ambient temperature, and the temperature of the external coil; the wind speed of the fan is divided into six gears, increasing in sequence from wind speed 1 to wind speed 6.

[0081] Table 4: Comparison table of the speed gears of the dual-air-duct fan during heating

[0082]

[0083] Table 5: Comparison table of the speed gears of the dual-air-duct fan during cooling

[0084]

[0085] Among them, if there are two coils in a single air duct, then when the system is in the heating mode or the hot water mode, the lower value of the two is taken for judgment; when the system is in the cooling mode, the higher value of the two is taken for judgment.

[0086] In the same air duct, if there are two coils, then the lowest one is selected for heating judgment and the highest one is selected for cooling judgment, that is, when the system is in the dual-system mode, the first fan corresponds to the first system and the second fan corresponds to the second system; the rotation speed of the first fan is determined by the frequency of the compressor 1 of the first system, the temperature of the external coil of the first system, and the ambient temperature; the rotation speed of the second fan is determined by the frequency of the compressor 1 of the second system, the temperature of the external coil of the second system, and the ambient temperature.

[0087] When the system is in the four-system mode, the first fan corresponds to the first and second systems, and the first fan also corresponds to the third and fourth systems; when controlling the fan speed, first compare the external coil temperatures of the first and second systems, and take the lower one (when refrigerating, take the higher one). If the external coil temperature of the first system is lower, the speed of the first fan is determined by the frequency of the compressor 1 of the first system, the external coil temperature of the first system, and the ambient temperature.

[0088] In a further embodiment of the present invention, a defrost mode is also included.

[0089] When the ambient temperature is greater than the preset extended defrost ambient temperature and the system simultaneously meets Condition 101 and Condition 102, the system enters the defrost mode; wherein, the extended defrost ambient temperature is the ambient temperature value preset by the user for the system to extend the defrost time.

[0090] When the ambient temperature is not greater than the preset extended defrost ambient temperature and the system simultaneously meets Condition 101, Condition 102 and Condition 103 or the system simultaneously meets Condition 101, Condition 102 and Condition 104, the system enters the defrost mode;

[0091] When the system meets any one of Condition 201, Condition 202, and Condition 203, the defrost mode is exited;

[0092] Wherein:

[0093] Condition 101: The compressor 1 has cumulatively run for the sum of the third time of 60 minutes, the adaptive time, and the constant temperature compensation time, and the compressor 1 has continuously run for the fourth time of 5 minutes;

[0094] Condition 102: The external coil temperature is not greater than the seventh temperature - 3°C for more than the fifth time of 3 minutes;

[0095] Condition 103: The difference between the ambient temperature and the external coil temperature is not less than the eighth temperature of 10°C;

[0096] Condition 104: The compressor 1 has cumulatively run for the sum of the sixth time of 60 minutes + 45 minutes, the adaptive time, and the constant temperature compensation time, and the compressor 1 has continuously run for the fourth time of 5 minutes;

[0097] Condition 201: The external coil temperature is greater than the ninth temperature of 15°C;

[0098] Condition 202: The defrost time reaches the seventh time of 10 minutes;

[0099] Condition 203: The outlet water temperature is not greater than the tenth temperature of 5°C and lasts for the eighth time of 3 seconds.

[0100] In a further embodiment of the present invention, the adaptive time is adjusted according to the defrost duration of each time of the system.

[0101] When the system's defrost duration is less than the ninth time, the adaptive time increases by five minutes;

[0102] When the defrost duration of the system is not less than the ninth time and less than the tenth time, the adaptive time remains unchanged;

[0103] When the defrost time of the system is not less than the tenth time, the adaptive time is reduced by five minutes.

[0104] In this embodiment, the system is provided with an adaptive time, and the system dynamically adjusts the time to start the next defrost operation according to the duration of each defrost operation, which can effectively improve the defrost efficiency of the system.

[0105] In a further embodiment of the present invention, after the system enters the defrost mode, the compressor 1 and the fan are turned off, the four-way valve 2 and the electric heater are started after a delay of 10 seconds, and the compressor 1 is restarted at an operating frequency of 70 Hz after a delay of 60 seconds; after the system exits the defrost mode, the compressor 1 is turned off, the four-way valve 2 and the electric heater are turned off after a delay of 50 seconds, the fan is restarted after a delay of 55 seconds, and the operation of the compressor 1 is resumed after 5 seconds, and the accumulated running time of the compressor 1 is cleared at the same time.

[0106] Please refer to Table 6 and Table 7. In a further embodiment of the present invention, the initial opening degree of the main expansion wiper is determined by the ambient temperature and the inlet water temperature. Specifically, when the system is in heating mode, please refer to Table 6 for the specific relationship between the initial opening degree of the main expansion wiper, the ambient temperature, and the inlet water temperature; when the system is in cooling mode, please refer to Table 7 for the specific relationship between the initial opening degree of the main expansion wiper, the ambient temperature, and the inlet water temperature.

[0107] Table 6: Comparison table of initial opening degree of main expansion valve 10 in heating mode

[0108]

[0109] Table 7: Comparison table of initial opening degree of main expansion valve 10 in heating mode

[0110]

[0111] The initial opening degree of the auxiliary expansion valve 10 is also determined by the ambient temperature and the inlet water temperature. Please refer to Table 8 for details.

[0112] Table 8: Comparison table of initial opening of auxiliary expansion valve 10

[0113]

[0114] Among them, the main expansion valve 10 is initialized to the default opening of 350P after the system is powered on, and 30 seconds before the compressor 1 is started, the main expansion valve 10 is opened to the initial opening according to the ambient temperature and the inlet water temperature.

[0115] When the main expansion valve 10 is opened to the initial opening, the control logic is:

[0116] EXVn=(EXVn-1)+[KP(DTCn-DTS)+KD(DTCn-DTCn-1)],

[0117] Among them, KP and KD are adjustable parameters, DTS is the set superheat (please refer to Table 9 for details), DTC is the actually measured superheat, EXVn is the actual opening of the electronic expansion valve, EXVn-1 is the previous opening of the electronic expansion valve, KP is the superheat proportional coefficient / 10, KD is the superheat differential coefficient, and DTCn is the actual target superheat. The actual target superheat in heating mode is return air temperature - coil temperature (in cooling mode, it is return air temperature - post-throttling temperature).

[0118] Table 9: Main expansion valve target superheat comparison table

[0119]

[0120] The control of the auxiliary expansion valve 10 is as follows: when heating, the unit is powered on and the compressor 1 is not running, the electronic expansion valve is first reset to zero; within 1 minute after the compressor 1 is powered on, the electronic expansion valve is opened to the initial opening degree; every 12 seconds (temperature measurement cycle: auxiliary adjustment cycle) the exhaust temperature is read to determine whether the exhaust temperature is greater than the set upper limit temperature. If it is greater than 95°C (parameter auxiliary exhaust setting), the opening and closing of the expansion valve are adjusted according to the PID control, hoping that the exhaust temperature will approach 95°C.

[0121] EXVn=(EXVn-1)+[KP(TDn-95)+KD(TDn-TDn-1)]

[0122] Among them, EXVn is the actual opening of the electronic expansion valve, EXVn-1 is the previous opening of the electronic expansion valve, KP is the auxiliary expansion valve superheat proportional coefficient / 10, KD is the auxiliary expansion valve superheat differential coefficient, DTCn is the actual target superheat (exhaust gas temperature - inlet water / tank temperature), DTS is the set exhaust gas superheat, and DTCn-1 is the previous target superheat.

[0123] In a further embodiment of the present invention, the control of various devices in the system includes:

[0124] Water pump; when the system requests to start the heating / cooling mode, the circulating water pump starts 90 seconds before the compressor; when the system requests to shut down, the circulating water pump will not shut down until 90 seconds after the compressor stops; when the machine is on, the circulating water pump operates in this mode.

[0125] Four-way valve 2; in heating or hot water mode, four-way valve 2 loses power; in defrosting and forced defrosting, four-way valve 2 is energized, refer to the defrost sequence; in cooling mode, four-way valve 2 is energized.

[0126] Three-way valve: When in the refrigeration or heating mode, the three-way valve is powered on; when in the hot water mode, the three-way valve is powered off.

[0127] Crankshaft electric heating; The crankshaft electric heating works when the following conditions are met: when the compressor is turned off and the outdoor ambient temperature T_env < 8°C; it is turned off when any of the following conditions is met: when the compressor starts or the outdoor ambient temperature T_env > 8°C.

[0128] Bypass valve 14; When conditions A1, B1, and C1 are met simultaneously or when conditions B1, C1, and D1 are met simultaneously, bypass valve 14 opens: Condition A1: Ambient temperature ≥ 13°C and inlet water temperature ≥ 5 °C; Condition B1: In the heating state or hot water state; Condition C1: The fan is turned on; Condition D1: Ambient temperature ≥ 12°C and exhaust 1 or 2 or 3 or 4 ≥ 150°C; When any of the following conditions is met, bypass valve 14 closes: Condition A2: Ambient temperature ≤ 11°C; Condition B2: Inlet water temperature ≤ 15°C; Condition C2: In the refrigeration state or defrost state or shutdown state; Condition D2: The fan is turned off.

[0129] Enhanced enthalpy valve; The enhanced enthalpy valve opens when the auxiliary expansion valve 10 opens; the enhanced enthalpy valve closes when the auxiliary expansion valve 10 closes.

[0130] Chassis electric heating; The chassis electric heating is turned on when the following conditions are met simultaneously: it is turned on when the ambient temperature ≤ 3°C; the unit operates in the defrost state or enters the defrost state due to an ambient temperature fault; The chassis electric heating exits conditions (when any of the following conditions is met): it is turned off 20 minutes after the defrost ends; the unit operates in the refrigeration state.

[0131] Auxiliary electric heating; Start conditions: in the heating or hot water mode; ambient temperature ≤ the parameter of electric heating ambient temperature; there is a heating demand; the circulation pump is in the running state; when all the above conditions are met simultaneously, the auxiliary electric heating is turned on. Shutdown conditions: in the refrigeration mode; there is no heating demand; a fault alarm occurs for the inlet water temperature sensor; ambient temperature ≥ 5°C (parameter: electric heating ambient temperature) + 2°C; water flow fault; the circulation pump is turned off; when any of the above conditions is met, the auxiliary electric heating stops. When the auxiliary electric heating is turned on, the circulation pump is turned on 30 seconds in advance; when the auxiliary electric heating is turned off, the circulation pump is turned off with a 30 - second delay.

[0132] In a further embodiment of the present invention, the system is also provided with multiple protection functions, including:

[0133] Three - phase protection; When powering on, the three - phase power is detected. If there is a phase error or phase loss, it enters the three - phase protection, and all outputs are turned off. Only after troubleshooting and powering on again can it be restored.

[0134] Ambient temperature fault; detected after the unit is powered on; if the ambient temperature thermal sensor is short-circuited or open-circuited at any time, it is judged as an ambient temperature thermal sensor fault, and the system shuts down; this fault can be recovered.

[0135] Water tank temperature fault 15E; detected after the unit is powered on; if the water tank thermal sensor is short-circuited or open-circuited at any time, it is judged as a water tank thermal sensor fault, and the system shuts down for protection when the water tank temperature fault occurs; this fault can be recovered.

[0136] Inlet water temperature fault; detected after the unit is powered on; if the inlet water temperature thermal sensor is short-circuited or open-circuited at any time, it is judged as an inlet water temperature thermal sensor fault, and the system shuts down for protection when the inlet water temperature fault occurs; this fault can be recovered.

[0137] Outlet water temperature fault 13E; detected after the unit is powered on; if the outlet water temperature thermal sensor is short-circuited or open-circuited at any time, it is judged as an outlet water temperature thermal sensor fault, and the system shuts down for protection; this fault can be recovered.

[0138] Coil temperature fault; detected after the unit is powered on; if the coil temperature thermal sensor is short-circuited or open-circuited at any time, it is judged as a coil temperature thermal sensor fault, and the system does not shut down; when this fault occurs, the electronic expansion valve control switches to manual adjustment, and defrosting is timed defrosting (the defrosting cycle is based on the parameter defrosting cycle, and the ambient temperature must meet the conditions to enter timed defrosting); this fault can be recovered.

[0139] Suction gas temperature fault; detected after the unit is powered on; if the suction gas temperature thermal sensor is short-circuited or open-circuited at any time, it is judged as a suction gas temperature thermal sensor fault, and the system does not shut down; when this fault occurs, the electronic expansion valve control switches to manual mode; this fault can be recovered.

[0140] Discharge gas temperature fault; after the unit is powered on, if the discharge gas temperature thermal sensor is short-circuited at any time or the discharge gas temperature thermal sensor is open-circuited continuously for 5 seconds after the compressor starts running for 5 minutes, it is judged as a discharge gas temperature thermal sensor fault, and the system shuts down for protection; this fault can be recovered.

[0141] Temperature fault after throttling; detected after the unit is powered on; if the temperature thermal sensor after throttling is short-circuited or open-circuited at any time, it is judged as a temperature thermal sensor fault after throttling; this fault can be recovered.

[0142] System high-pressure protection; after the compressor starts for 5 seconds, if the high-pressure switch is detected to be open for 5 consecutive seconds, it enters high-pressure protection, and the corresponding system shuts down for protection; an alarm is given and the fault code is displayed; after the compressor meets the requirement of a 3-minute delay, the switch closes and the fault is recovered.

[0143] System low-pressure protection: After the press is turned on for 10 minutes, the low-pressure protection switch is detected. If this switch is continuously detected to be off for 10 seconds, the corresponding system will stop for protection, alarm, and display a fault code. If a fault occurs 3 times within 1 hour (note: if the number is less than 3 times within 1 hour, the count is cleared), the system will stop and alarm, and display the fault code on the main interface, locking the fault. The system will not be detected within 10 minutes after the press starts, during the defrost period, or when the ambient temperature ≤ -15°C.

[0144] Exhaust temperature overheat protection: After the press is turned on for 1 minute, it is detected. If the exhaust temperature ≥ 120° (parameter: high exhaust temperature) is continuously detected for 5 seconds, the corresponding system will stop for protection, alarm, and display a fault code. When the detected exhaust temperature ≤ 85°C, this protection is exited. If a fault occurs 3 times within 1 hour (note: if the number is less than 3 times within 1 hour, the count is cleared), the system will stop and alarm.

[0145] Water flow switch protection: After the circulating water pump starts for 1 minute, the water flow switch is detected. If this switch is continuously detected to be off for 10 seconds, the system will stop for protection. After this fault occurs, if the fault has not been restored, the water pump will be restarted every 5 minutes to run and detect the water flow. If the water flow switch has not been restored after restarting the water pump 3 times within 1 hour, the water pump will no longer be restarted. This fault can be restored even if it is locked by closing the switch;

[0146] Winter anti-freezing protection: To prevent the circulating water from freezing in winter, the unit automatically enters the anti-freezing protection when the following conditions are met. In the shutdown state, constant temperature, or fault shutdown state, the ambient temperature and the outlet water temperature are detected. When the ambient temperature ≤ 4°C, the first-level anti-freezing protection is entered, and the circulating water pump is turned on for 5 minutes every 15 minutes for circulating operation. When the ambient temperature ≥ 6°C, the first-level anti-freezing protection is exited (not restricted by time). When the ambient temperature ≤ 4°C and the outlet water temperature ≤ 2°C, the second-level anti-freezing protection is entered, and the unit automatically starts to heat. When the ambient temperature ≥ 6°C or the outlet water temperature ≥ 15°C, the heating stops and the anti-freezing protection is exited. If there is a fault in the ambient temperature sensor, only the outlet water temperature is detected. If both the ambient temperature sensor and the outlet water temperature sensor are faulty, the anti-freezing function is cancelled.

[0147] Refrigeration outlet water subcooling protection: When the unit is operating in the refrigeration mode, after the compressor starts, when the detected outlet water temperature ≤ 5°C, it is judged as refrigeration outlet water subcooling protection, and the fault code is displayed; Compressor 1 and the fan stop running, and the water pump runs as normal. After the refrigeration outlet water subcooling protection occurs, when the detected outlet water temperature ≥ 7°C, the protection is exited and the unit operates normally. This fault can be restored.

[0148] Compressor 1 module fault protection: When there is a corresponding fault in the variable frequency drive module, the whole unit stops and reports the corresponding module fault.

[0149] Protection against excessive temperature difference between inlet and outlet water; For the cooling / heating / mode, after the compressor 1 starts for 1 minute, if the temperature difference between the outlet water temperature and the inlet water temperature is continuously detected to be ≥ 13 °C (parameter: excessive temperature difference) for 10 consecutive seconds, it is determined that the system water flow is insufficient, and the whole machine stops and alarms. When the temperature difference between the outlet water temperature and the inlet water temperature ≤ 5 °C, and the compressor stops for more than 3 minutes and then restarts.

[0150] Drive module communication failure; If the main board has not received the communication signal from the drive module for 20 consecutive seconds, it is judged as a drive module communication failure.

[0151] Low ambient temperature protection

[0152] When the ambient temperature < parameter low temperature setting, the system stops for protection, turns on the electric heating, and alarms; When the ambient temperature ≥ parameter low temperature setting + 2 °C, the system returns to normal;

[0153] Low pressure sensor failure; Detected after the unit is powered on; When a low pressure sensor is selected, at any time after the compressor 1 starts for 10 minutes, if the low pressure temperature sensor is detected to be short-circuited or open-circuited, it is judged as a low pressure sensor failure, and the system does not stop; When this failure occurs, the electronic expansion valve control switches to manual adjustment; This failure can be restored.

[0154] Fan 1 / 2 overload protection; After the fan is turned on, if the fan overload switch is detected to be disconnected for 5 consecutive seconds, it enters the fan overload protection, and the corresponding system stops for protection; Alarms and displays the fault code; After the fan meets the requirement of 3-minute delay, the switch closes and the fault is restored;

[0155] Low pressure protection; When the compressor is off or after the compressor has been on for 10 minutes, if the detection value of the low pressure sensor is continuously ≤ parameter H25 for 5 seconds, it reports that the pressure of the EC low pressure 1 sensor is too low and the pressure of the EC2 low pressure 2 sensor is too low; After the protection is triggered, after 1 minute, when the detection value of the low pressure sensor is continuously ≥ parameter H25 + 100 kpa for 5 seconds, it returns to normal; If this protection occurs 3 times within 30 minutes, the unit is locked.

[0156] Exhaust temperature protection; When TE ≥ 120 °C for 5 seconds, the unit stops; When TE ≥ 110 °C, the frequency drops by 1 Hz / 4S, and if it drops to the lowest frequency, it remains; When TE ≥ 105 °C, the frequency drops by 1 Hz / 5S, and if it drops to the lowest frequency, it remains; When TE ≥ 100 °C, the frequency drops by 1 Hz / 10S, and if it drops to the lowest frequency, it remains; When TE ≥ 95 °C, the frequency is prohibited from rising but allowed to drop; When TE < 95 °C, after 1 minute, the frequency is normally controlled; After the exhaust temperature protection stops for 3 minutes, when TE ≤ 95 °C, it resumes normal operation; Where TE is the exhaust temperature.

[0157] Outdoor coil high-temperature protection; When To≥65°C for 5 seconds, the unit shuts down; When To≥60°C, the frequency decreases by 1Hz / 5S. If it drops to the minimum frequency, it remains at that frequency; When To≥55°C, the frequency is prohibited from increasing but allowed to decrease; When To<55°C, the frequency operates normally; After the unit shuts down due to high-temperature protection of the outdoor coil for 3 minutes, when To≤55°C, it resumes normal operation; where To is the temperature of the outdoor coil.

[0158] Please refer to Figure 4-7 , In one embodiment of the present invention, a multi-system low-temperature cold and hot water machine is provided. This hot water machine uses a control method for a multi-system low-temperature cold and hot water machine in the present invention. For details, please refer to Figure 4-7 , wherein,; wherein, Figure 4 The circuit structure diagram of the system high and low pressure sensor ports is provided, which is used for the main control module to be connected to the high and low pressure sensors. Figure 5 The circuit structure diagram of the system main control module is provided. The main control module is used to control the operation in the low-temperature cold and hot water machine. Figure 6 The circuit structure diagrams of the optocoupler isolation protection module and the step-down module are provided. Figure 7 The circuit structure diagram of the relay electronic expansion valve part is provided, which is used for the main control module to control electrical appliances such as fans and water pumps.

[0159] As mentioned above, the above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A control method for a multi-system low-temperature cold and hot water machine, which is applied to a low-temperature cold and hot water machine provided with a four-heat pump system and a double air duct, is characterized in that, The four heat pump system includes a first heat pump, a second heat pump, a third heat pump, and a fourth heat pump that are arranged in parallel. The dual air duct includes a first air duct connected to the first heat pump and the second heat pump, and a second air duct connected to the third heat pump and the fourth heat pump. A first fan is arranged in the first air duct, and a second fan is arranged in the second air duct. The external coils connected to the first heat pump and the external coils connected to the second heat pump are arranged in the first air duct and exchange heat with the outside through the first air duct. The external coils connected to the third heat pump and the external coils connected to the fourth heat pump are arranged in the second air duct and exchange heat with the outside through the second air duct; Among them, the working modes of the system include single-system working, dual-system working, and four-system working. When the user selects single-system working, the cold and hot water machine operates in a single air duct. When the user selects dual-system working, the cold and hot water machine adjusts to operate in a single air duct or a dual air duct according to the user's selection. When the user selects four-system working, the cold and hot water machine operates in a dual air duct.

2. The control method of a multi-system low-temperature cold and hot water machine according to claim 1, characterized in that, When the air duct control is in single air duct, when the system operates, the fan is turned on first, and the compressor (1) is turned on after the first time. When the system shuts down, the compressor (1) is turned off first, and the fan is turned off after the second time. The system adjusts the speed of the fan according to the ambient temperature.

3. A control method for a multi-system low-temperature cold and hot water machine according to claim 2, characterized in that, When the air duct control is in single air duct and the system is in dual-system working, the system adjusts the speed of the fan according to the ambient temperature and the inlet water temperature.

4. A control method for a multi-system low-temperature cold and hot water machine according to claim 3, characterized in that, When the air duct control is in single air duct and the system is in dual-system working, the wind speed of the fan is: When the system is heating, when the temperature is less than the first temperature or the inlet water temperature is less than the second temperature, the fan runs at high speed. When the ambient temperature is greater than the third temperature and the inlet water temperature is greater than the fourth temperature, the fan runs at low speed. When the ambient temperature is greater than the third temperature and the inlet water temperature is less than the second temperature, the fan runs at high speed. When the ambient temperature is not less than the first temperature and not greater than the third temperature, or the purified water temperature is not less than the second temperature and not greater than the fourth temperature, the fan runs at low speed; When the system is cooling, when the ambient temperature is greater than the fifth temperature, the fan runs at high speed. When the ambient temperature is less than the sixth temperature, the fan runs at low speed. When the ambient temperature is not less than the sixth temperature and not greater than the fifth temperature, the fan maintains the original operating speed.

5. A control method for a multi-system low-temperature cold and hot water machine according to claim 1, characterized in that, When the air duct control is in dual air duct, the system adjusts the speed of the fan according to the operating frequency of the compressor (1), the ambient temperature, and the temperature of the external coil; Among them, if both coils in a single air duct are working, then when the system is heating, the lower value of the two is taken for judgment. When the system is cooling, the higher value of the two is taken for judgment.

6. A control method for a multi-system low-temperature cold and hot water machine according to claim 1, characterized in that, It also includes a defrosting mode. When the ambient temperature is greater than the preset extended defrosting ambient temperature, and the system simultaneously meets condition 101 and condition 102, the system enters the defrosting mode; When the ambient temperature is not greater than the preset extended defrosting ambient temperature, and the system simultaneously meets condition 101, condition 102, and condition 103, or the system simultaneously meets condition 101, condition 102, and condition 104, the system enters the defrosting mode; Among them: Condition 101: The compressor (1) has accumulated operation for the sum of the third time, the adaptive time, and the constant temperature compensation time, and the compressor (1) has continuously operated for the fourth time; Condition 102: The temperature of the outer coil is not greater than the seventh temperature for more than the fifth time; Condition 103: The difference between the ambient temperature and the temperature of the outer coil is not less than the eighth temperature; Condition 104: The compressor (1) has run for a cumulative time equal to the sum of the sixth time, the adaptive time, and the constant temperature compensation time, and the compressor (1) has run continuously for the fourth time.

7. A control method for a multi-system low-temperature cold and hot water machine according to claim 6, characterized in that, When the system is in the defrost mode and meets any one of Condition 201, Condition 202, and Condition 203, the defrost mode is exited; Wherein: Condition 201: The temperature of the outer coil is greater than the ninth temperature; Condition 202: The defrost time reaches the seventh time; Condition 203: The outlet water temperature is not greater than the tenth temperature and lasts for the eighth time.

8. A control method for a multi-system low-temperature cold and hot water machine according to claim 6, characterized in that, The adaptive time is adjusted according to the defrost duration of each time of the system; When the defrost duration of the system is less than the ninth time, the adaptive time increases by the eleventh time; When the defrost duration of the system is not less than the ninth time and less than the tenth time, the adaptive time remains unchanged; When the defrost duration of the system is not less than the tenth time, the adaptive time decreases by the eleventh time.

9. The control method of a multi-system low-temperature cold and hot water machine according to claim 6, characterized in that, After the system enters the defrost mode, the compressor (1) and the fan are turned off. After a delay of the twelfth time, the four-way valve (2) and the electric heater are started. After a delay of the thirteenth time, the compressor (1) is restarted at the operating frequency of the first frequency.

10. A control method for a multi-system low-temperature cold and hot water machine according to claim 7, characterized in that, After the system exits the defrost mode, the compressor (1) is turned off. After a delay of the fourteenth time, the four-way valve (2) and the electric heater are turned off. After a delay of the fifteenth time, the fan is restarted and the compressor (1) resumes operation after the sixteenth time. At the same time, the cumulative operating time of the compressor (1) is cleared.

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