Variable frequency heat pump unit and heat dissipation control method

Abstract

The application discloses a variable frequency heat pump unit and a heat dissipation control method. The variable frequency heat pump unit comprises a refrigerant circulation loop and a variable frequency driving module. The refrigerant circulation loop is connected to form a combination of a compressor, a heat exchanger, a liquid accumulator and a gas-liquid separator. The variable frequency driving module is provided with a heat dissipation pipeline. The outlet end of the heat dissipation pipeline is connected to the suction side of the compressor. The inlet end of the heat dissipation pipeline is communicated with the liquid storage cavity of the liquid accumulator through a first branch and a second branch. The first branch is provided with a cooling pipe section located in the gas-liquid separator. The outlet side of the cooling pipe section is provided with a first throttling device. The second branch is located outside the gas-liquid separator. The second branch is provided with a second throttling device. The opening degrees of the first throttling device and the second throttling device are adjustable and work cooperatively. The application can reduce the influence of heat dissipation on the main loop circulation by leading the liquid refrigerant in the liquid accumulator to dissipate heat for the variable frequency driving module, and can balance the heat dissipation efficiency and the unit performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump units, in particular to a variable frequency heat pump unit and a heat dissipation control method. BACKGROUND

[0002] Variable frequency units have become the mainstream equipment in the field of heating, ventilation and air conditioning by virtue of the characteristics of end load matching and low load high efficiency operation realized by frequency regulation, but with the upgrading of technology and the expansion of application scenarios, the core component heat dissipation problem and multi-mode flow path management problem of the variable frequency unit have become increasingly prominent, which restricts the performance of the unit under different working conditions.

[0003] In the variable frequency unit, the IPM (intelligent power module) as the core electrical control device for driving the compressor, its heat dissipation performance directly affects the compressor efficiency and operation stability. The current industry generally adopts air cooling or refrigerant heat dissipation scheme to solve the IPM heating problem: air cooling relies on the convective heat transfer of the condenser environment airflow and the heat dissipation fins, but when the outdoor environment temperature is high, the airflow temperature after the condenser increases significantly, resulting in a significant decrease in IPM heat dissipation efficiency, and the compressor is forced to limit the operating frequency due to insufficient heat dissipation; the refrigerant heat dissipation exchanges heat with the IPM through low-temperature liquid refrigerant, although it has more stable heat dissipation characteristics, but in high temperature environment, the temperature of the refrigerant itself rises, the temperature difference between the refrigerant and the IPM decreases, and the heat dissipation effect is also weakened, and the risk of high-pressure refrigerant leakage increases with the complexity of the pipeline.

[0004] At the same time, in order to realize heat recovery or four-pipe system function (such as simultaneously meeting the refrigeration and heating requirements), the new type of variable frequency unit often needs to switch the refrigerant flow path according to different modes (refrigeration, heating, heat recovery), and the refrigerant flowing out of the condenser needs to pass through the IPM after switching the mode, which design leads to an increase in system pipeline length, an increase in elbows, an increase in refrigerant flow resistance (significant along the way pressure loss), not only reduces the subcooling degree, but also causes part of the refrigerant to be unable to effectively participate in heat exchange due to the long pipeline, resulting in no heat exchange loss; when switching the multi-mode flow path, the refrigerant needs to be frequently distributed to different heat exchangers, and part of the refrigerant occupies the evaporator space due to the redundant flow path design, resulting in a decrease in the effective heat exchange area of the evaporator and a decrease in the heat exchange efficiency of the unit; at the same time, improper refrigerant flow control will directly affect the stability of the main loop circulation and exacerbate the instability of IPM heat dissipation.

[0005] Therefore, how to design a variable frequency heat pump unit and a heat dissipation control method that can balance heat dissipation efficiency and unit performance is a technical problem that needs to be solved in the industry. SUMMARY

[0006] In order to solve the defects of unstable IPM heat dissipation and low performance of the existing heat pump unit, the application provides a variable frequency heat pump unit and a heat dissipation control method, liquid refrigerant in the liquid accumulator is used to dissipate heat to the variable frequency drive module, and then gaseous refrigerant after heat dissipation is sent back to the suction side of the compressor, so that the influence of heat dissipation on the main loop circulation is reduced, harmful pressure drop of the refrigerant circulation loop is effectively reduced, the evaporator is fully utilized, and the performance of the unit is improved.

[0007] The technical scheme adopted by the application is that a variable frequency heat pump unit is designed, which comprises a refrigerant circulation loop and a variable frequency drive module, the refrigerant circulation loop is connected to form by a compressor, a heat exchanger combination, a liquid accumulator and a gas-liquid separator, the heat exchanger combination comprises three heat exchangers, and at least two heat exchangers participate in the refrigerant circulation of the refrigerant circulation loop; the variable frequency drive module is provided with a heat dissipation pipeline, the outlet end of the heat dissipation pipeline is connected to the suction side of the compressor, the inlet end of the heat dissipation pipeline is communicated with the liquid storage cavity of the liquid accumulator through a first branch and a second branch, the first branch is provided with a cooling pipe section located in the gas-liquid separator, a first throttling device is installed on the outlet side of the cooling pipe section, the second branch is located outside the gas-liquid separator, and a second throttling device is installed on the second branch; wherein the opening degrees of the first throttling device and the second throttling device are adjustable and work cooperatively.

[0008] Further, the three heat exchangers are a first heat exchanger, a second heat exchanger and a third heat exchanger, the exhaust side of the compressor can be connected to the first end of any one of the heat exchangers; the second end of the first heat exchanger is connected to the liquid accumulator through a first outlet pipe and a first inlet pipe; the second end of the second heat exchanger is connected to the liquid accumulator through a second outlet pipe; the second end of the third heat exchanger is connected to the liquid accumulator through a third outlet pipe and a third inlet pipe; wherein each outlet pipe is provided with a control valve allowing the refrigerant to flow to the liquid accumulator, and each inlet pipe is provided with a throttling device.

[0009] Further, the second end of the second heat exchanger is also connected to the liquid accumulator through a second inlet pipe.

[0010] Further, the first heat exchanger is an air conditioning water heat exchanger, the second heat exchanger is a hot water heat exchanger, and the third heat exchanger is an outdoor heat exchanger, and the working mode of the variable frequency heat pump unit comprises at least one of a refrigeration mode, a heating mode, a hot water mode, a refrigeration and hot water mode, and a heating and hot water mode.

[0011] In some embodiments, the first throttling device and the second throttling device are both electronic expansion valves.

[0012] The application also provides a heat dissipation control method, which is applied to the variable frequency heat pump unit, and the heat dissipation control method comprises the following steps:

[0013] The working mode of the variable frequency heat pump unit and the condensing side heat medium temperature of the refrigerant circulation loop are obtained.

[0014] comparing the condensing side heat exchange medium temperature with a set inflection point temperature corresponding to the current working mode;

[0015] if the condensing side heat exchange medium temperature > the set inflection point temperature, a first heat dissipation strategy mainly regulated by the first throttling device is executed;

[0016] if the condensing side heat exchange medium temperature < the set inflection point temperature, a second heat dissipation strategy mainly regulated by the second throttling device is executed.

[0017] Further, the first heat dissipation strategy comprises:

[0018] acquiring an actual temperature of the variable frequency drive module;

[0019] when the actual temperature ≥ a set temperature B, the opening of the first throttling device is increased;

[0020] when the actual temperature < the set temperature B, the first throttling device is controlled to maintain a set initial opening, and the opening of the second throttling device is adjusted according to a set slow speed mode.

[0021] Further, the second heat dissipation strategy comprises:

[0022] acquiring an actual temperature of the variable frequency drive module;

[0023] when the actual temperature ≥ a set temperature B1, the opening of the second throttling device is increased, and if the second throttling device is opened to the maximum opening, the opening of the first throttling device is increased;

[0024] when the actual temperature ≤ a set temperature A1, the first throttling device is closed, and the opening of the second throttling device is adjusted according to a set slow speed mode;

[0025] when the set temperature A1 < the actual temperature < the set temperature B1, the first throttling device is controlled to maintain the current opening, and the opening of the second throttling device is adjusted according to a set fast speed mode.

[0026] Further, the set slow speed mode comprises:

[0027] acquiring an actual superheat degree of the heat dissipation pipeline;

[0028] when the actual superheat degree > a set superheat degree ΔC1, the opening of the second throttling device is increased every set time E1;

[0029] when the actual superheat degree < a set superheat degree ΔD1, the opening of the second throttling device is decreased every set time E1;

[0030] when the set temperature ΔD1 < the actual temperature < the set temperature ΔC1, the opening of the second throttling device is maintained.

[0031] Further, the setting fast mode includes:

[0032] Acquiring an actual overheat degree of the heat dissipation pipeline;

[0033] When the actual overheat degree > setting overheat degree ΔC2, the opening of the second throttling device is increased every interval setting time E2;

[0034] When the actual overheat degree < setting overheat degree ΔD2, the opening of the second throttling device is decreased every interval setting time E2;

[0035] When setting temperature ΔD2 < actual temperature < setting temperature ΔC2, the opening of the second throttling device is maintained;

[0036] Wherein, setting time E2 < setting time E1.

[0037] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0038] 1. The heat dissipation pipeline of the variable frequency drive module is connected between the liquid storage cavity of the liquid accumulator and the suction side of the compressor, the liquid refrigerant accumulated in the liquid accumulator is led out to dissipate heat to the variable frequency drive module, and then the gaseous refrigerant after heat dissipation is sent back to the suction side of the compressor, thereby reducing the influence of heat dissipation on the main loop circulation, effectively reducing the harmful pressure drop of the refrigerant circulation loop and fully utilizing the evaporator, and improving the performance of the unit;

[0039] 2. The heat dissipation pipeline is connected to the liquid storage cavity of the liquid accumulator through two branches, one branch does not pass through the gas-liquid separator, and the liquid refrigerant directly enters the heat dissipation pipeline to dissipate heat to the variable frequency drive module, and the other branch passes through the gas-liquid separator for cooling, thereby improving the heat dissipation effect of the variable frequency drive module, flexibly adjusting the two branches, reducing the temperature fluctuation of the variable frequency drive module, and improving the stability of the unit;

[0040] 3. The inflection point temperature is designed for different working modes, the temperature characteristics of the condensing side heat exchange medium of each mode are accurately matched, the heat dissipation strategy is dynamically adjusted, the adaptability problem of the traditional single heat dissipation scheme under high / low temperature working conditions is solved, the temperature stability of the variable frequency drive module is ensured under all scenes, and the reliability and energy efficiency level of the unit are significantly enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0041] The present application will be described in detail below in conjunction with the embodiments and drawings, in which:

[0042] Figure 1 is a preferred embodiment connection diagram of the variable frequency heat pump unit of the present application;

[0043] Figure 2 is a feasible embodiment connection diagram of the variable frequency heat pump unit of the present application;

[0044] Figure 3 This is a schematic diagram of the refrigerant flow direction in the refrigeration mode of the present invention;

[0045] Figure 4 This is a schematic diagram of the refrigerant flow direction in the heating mode of this invention;

[0046] Figure 5 This is a schematic diagram of the refrigerant flow direction in the hot water mode of the present invention;

[0047] Figure 6 This is a schematic diagram of the refrigerant flow direction in the cooling and heating water mode of the present invention;

[0048] Figure descriptions: 1. Compressor; 2. First heat exchanger; 3. Second heat exchanger; 4. Third heat exchanger; 5. Liquid receiver; 6. Gas-liquid separator; 7. First check valve; 8. Second check valve; 9. Third check valve; 10. Refrigeration throttling device; 11. Heating throttling device; 12. Defrosting throttling device; 13. First four-way valve; 14. Second four-way valve; 15. Variable frequency drive module; 16. First throttling device; 17. Second throttling device. Detailed Implementation

[0049] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. 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.

[0050] like Figure 1 , 2 As shown, the variable frequency heat pump unit proposed in this invention includes, but is not limited to, heat recovery heat pump units. The variable frequency heat pump unit has variable frequency power components (such as variable frequency compressors and variable frequency fans), which are controlled by a variable frequency drive module 15. The variable frequency drive module 15 includes power switching devices (such as IPMs). During the operation of the heat pump unit, the variable frequency drive module 15 generates a significant heat load due to power loss, requiring continuous heat dissipation to maintain its operating temperature within the allowable range to ensure the long-term operational stability of the heat pump unit.

[0051] Specifically, the variable frequency heat pump unit comprises: a refrigerant circulation loop and a variable frequency drive module 15, the refrigerant circulation loop is connected to form by a compressor 1, a heat exchanger combination, a liquid accumulator 5, and a gas-liquid separator 6, the heat exchanger combination comprises three heat exchangers, and at least two heat exchangers participate in the refrigerant circulation of the refrigerant circulation loop. By designing the pipeline connection structure in the unit, the compressor 1 can be connected with the liquid accumulator 5 and any two heat exchangers to form a refrigerant circulation loop, the refrigerant flowing out of the condenser in the refrigerant circulation loop always passes through the liquid accumulator 5 and then flows to the evaporator, and the gas-liquid separator 6 is connected to the suction side of the compressor 1. The variable frequency drive module 15 is provided with a heat dissipation pipeline, the inlet end of the heat dissipation pipeline is communicated with the liquid storage cavity of the liquid accumulator 5, the outlet end of the heat dissipation pipeline is connected to the suction side of the compressor 1, and the inlet end of the heat dissipation pipeline is provided with a throttling device.

[0052] This design realizes efficient heat dissipation of the variable frequency drive module (IPM) 15 by utilizing the latent heat of phase change of the low-temperature liquid refrigerant in the liquid accumulator 5 and dynamically adjusting the refrigerant flow combined with the throttling device. The attenuation problem of the traditional air cooling / refrigerant cooling in the high-temperature environment is avoided, the incomplete evaporation or pressure fluctuation caused by excessive refrigerant is avoided through throttling control, the influence of heat dissipation on the main loop circulation is reduced, the harmful pressure drop of the refrigerant circulation loop and the full use of the evaporator are effectively reduced, the energy consumption is low, the system structure is simplified, the IPM temperature stability and the unit full working condition reliability are improved.

[0053] Specifically, the inlet end of the heat dissipation pipeline is communicated with the liquid storage cavity of the liquid accumulator 5 through a first branch and a second branch, the first branch is provided with a cooling pipe section located in the gas-liquid separator 6, a first throttling device 16 is installed on the outlet side of the cooling pipe section, and the liquid refrigerant is cooled through the cooling pipe section to improve the heat dissipation effect of the variable frequency drive module 15. The second branch is located outside the gas-liquid separator 6, the second branch is provided with a second throttling device 17, and the liquid refrigerant directly enters the heat dissipation pipeline to perform normal heat dissipation on the variable frequency drive module 15 without passing through the gas-liquid separator 6.

[0054] Because the temperature of the condensing side heat exchange medium is different in each mode, the temperature of the refrigerant sent into the liquid accumulator 5 fluctuates, and the heat dissipation effect of the variable frequency drive module changes, therefore, the preferred scheme is to design the first branch and the second branch at the same time, to flexibly adjust the refrigerant amount and the refrigerant temperature by using the two branches, to reduce the temperature fluctuation of the variable frequency drive module 15, and to improve the unit stability.

[0055] For the convenience of understanding, the three heat exchangers are a first heat exchanger 2, a second heat exchanger 3 and a third heat exchanger 4, and the first end and the second end of each heat exchanger have been marked on the connection diagram of the variable frequency heat pump system, the first end is marked as "①", and the second end is marked as "②".

[0056] The exhaust side of the compressor 1 can switch to connect the first end of any heat exchanger, the second end of the first heat exchanger 2 is connected to the liquid accumulator 5 through the first outlet pipe and the first inlet pipe, the second end of the second heat exchanger 3 is connected to the liquid accumulator 5 through the second outlet pipe, the second end of the third heat exchanger 4 is connected to the liquid accumulator 5 through the third outlet pipe and the third inlet pipe, each outlet pipe is provided with a control valve allowing the refrigerant to flow to the liquid accumulator 5, the first inlet pipe is provided with a refrigeration throttling device 10, the third inlet pipe is provided with a heating throttling device 11, and the throttling device controls the on-off state of the inlet pipe, and the outlet pipe and the inlet pipe extend into the liquid storage cavity of the liquid accumulator 5.

[0057] When the compressor 1 is connected to the first end of a certain heat exchanger, the heat exchanger serves as a condenser, the second end of the heat exchanger is the condenser outlet side, and the refrigerant flowing out of the second end can enter the liquid accumulator 5 through the outlet pipe and the control valve, and the liquid refrigerant in the liquid accumulator 5 is sent into the evaporator from the inlet pipe and the throttling device under the action of pressure.

[0058] This design can flexibly switch the flow direction of the refrigerant in the refrigerant circulation loop to meet the different needs of users, control the refrigerant distribution state of the heat exchanger through the throttling device, deeply simplify the system structure of the unit, reduce the length and complexity of the system pipeline, reduce the flow resistance of the refrigerant, reduce the heat exchange loss, and improve the heat exchange efficiency of the unit.

[0059] In addition, the control valve in the above can adopt an electromagnetic valve with switchable on-off state, or a one-way valve, the control valve of the first heat exchanger 2 is a first one-way valve 7, the control valve of the second heat exchanger 3 is a second one-way valve 8, and the control valve of the third heat exchanger 4 is a third one-way valve 9, which utilizes the one-way conduction characteristic of the one-way valve to ensure that the refrigerant can only flow from the heat exchanger to the liquid accumulator 5, avoid the reverse flow of the refrigerant in different modes, causing system pressure disorder or efficiency decline, without additional electronic control signals, and reducing the complexity of valve adjustment.

[0060] On this basis, in order to further optimize the variable frequency heat pump unit, the second end of the second heat exchanger 3 is connected to the liquid accumulator 5 through the second inlet pipe, the second inlet pipe extends into the liquid storage cavity of the liquid accumulator 5, and the second inlet pipe is provided with a defrost throttling device 12 for controlling the on-off state of the second inlet pipe. The second inlet pipe is connected when the third heat exchanger 4 serves as a condenser and the second heat exchanger 3 serves as an evaporator (i.e. during the defrosting process of the third heat exchanger 4, the second heat exchanger 3 participates in the refrigerant circulation), and the first inlet pipe and the third inlet pipe are both turned off.

[0061] The role of this design is that when the third heat exchanger 4 has defrosting demand, the second inlet pipe connecting the second heat exchanger 3 and the third heat exchanger 4 can be selected to use the high-temperature refrigerant discharged by the compressor 1 to defrost the third heat exchanger 4, and the refrigerant flowing out of the third heat exchanger 4 is sent to the liquid accumulator 5 and then to the second heat exchanger 3 through the second inlet pipe, so that the flexibility of the heat pump unit is higher and the adaptability to the environment is better. For example, in the hot water mode (the second heat exchanger 3 acts as a condenser and the third heat exchanger 4 acts as an evaporator), if the third heat exchanger 4 has defrosting demand during preparation of hot water, the refrigerant flow direction can be adjusted, the second inlet pipe is turned on, and the first inlet pipe and the second inlet pipe are turned off, and the refrigerant circulation loop performs a defrosting cycle.

[0062] Based on the above connection structure, the first heat exchanger 2 is an air conditioning water heat exchanger, the second heat exchanger 3 is a hot water heat exchanger, and the third heat exchanger 4 is an outdoor heat exchanger. The working modes of the variable frequency heat pump unit include at least one of a refrigeration mode, a heating mode, a hot water mode, a refrigeration and hot water mode, and a heating and hot water mode. The running states of the three heat exchangers in different working modes are described in detail below.

[0063] As shown in Figure 3 When the variable frequency heat pump unit operates in the refrigeration mode, the first heat exchanger 2 acts as an evaporator, the third heat exchanger 4 acts as a condenser, and the second heat exchanger 3 does not participate in the refrigerant circulation. The exhaust side of the compressor 1 is connected to the first end of the third heat exchanger 4, and the refrigerant flow direction of the refrigerant circulation loop is compressor 1→third heat exchanger 4→liquid accumulator 5→refrigeration throttling device→first heat exchanger 2→return to the compressor 1.

[0064] As shown in Figure 4 When the variable frequency heat pump unit operates in the heating mode, the first heat exchanger 2 acts as a condenser, the third heat exchanger 4 acts as an evaporator, and the second heat exchanger 3 does not participate in the refrigerant circulation. The exhaust side of the compressor 1 is connected to the first end of the first heat exchanger 2, and the refrigerant flow direction of the refrigerant circulation loop is compressor 1→first heat exchanger 2→liquid accumulator 5→heating throttling device 11→third heat exchanger 4→return to the compressor 1.

[0065] As shown in Figure 5 When the variable frequency heat pump unit operates in the hot water mode, the second heat exchanger 3 acts as a condenser, the third heat exchanger 4 acts as an evaporator, and the first heat exchanger 2 does not participate in the refrigerant circulation. The exhaust side of the compressor 1 is connected to the first end of the second heat exchanger 3, and the refrigerant flow direction of the refrigerant circulation loop is compressor 1→second heat exchanger 3→liquid accumulator 5→heating throttling device 11→third heat exchanger 4→return to the compressor 1.

[0066] As shown in Figure 6As shown, when the variable frequency heat pump unit operates in the refrigeration and heating water mode (heat recovery mode), the first heat exchanger 2 acts as an evaporator, the second heat exchanger 3 acts as a condenser, the third heat exchanger 4 does not participate in the refrigerant circulation, the exhaust side of the compressor 1 is connected to the first end of the second heat exchanger 3, and the refrigerant flow direction of the refrigerant circulation loop is compressor 1→ second heat exchanger 3→ liquid accumulator 5→ refrigeration throttling device 10→ first heat exchanger 2→ return to the compressor 1.

[0067] When the variable frequency heat pump unit operates in the heating and heating water mode, the third heat exchanger 4 acts as an evaporator, and the condenser is determined according to the priority of heating and heating water. If heating is prioritized, the heat pump unit first works in the heating state (see Figure 4 ), the first heat exchanger 2 is the condenser, and the second heat exchanger 3 does not participate in the refrigerant circulation; if heating water is prioritized, the heat pump unit first works in the heating water state (see Figure 5 ), the second heat exchanger 3 is the condenser, and the first heat exchanger 2 does not participate in the refrigerant circulation. In this mode, after the current function reaches the shutdown condition, it is determined whether the other function meets the startup condition, and if so, the function is started. For example, when heating is prioritized, the heating function reaches the shutdown condition, and it is determined whether the heating water function meets the startup condition, and if so, the heating water function is started, until the heating water function reaches the shutdown condition.

[0068] This design integrates multiple heat exchangers, including air conditioning water heat exchangers, hot water heat exchangers, and outdoor heat exchangers, in the heat pump unit. It can select the type and number of operating modes of the heat pump system configuration according to the needs of the application scenario, and can also recover the heat of the refrigerant for heating domestic hot water / heating, achieving energy cascade utilization and improving the energy efficiency of the unit.

[0069] In the preferred embodiment, the working mode of the heat pump unit includes the five working modes mentioned above. To achieve more accurate and reliable switching to different working modes, the compressor 1 is connected to the three heat exchangers through two four-way valves. As shown in Figure 1 , 2 Specifically, the D end of the first four-way valve 13 is connected to the exhaust side of the compressor 1, the E end is connected to the first end of the first heat exchanger 2, the S end is connected to the suction side of the compressor 1, and the C end is connected to the D end of the second four-way valve 14. The C end of the second four-way valve 14 is connected to the first end of the third heat exchanger 4, the E end is connected to the first end of the second heat exchanger 3, and the S end is connected to the suction side of the compressor 1.

[0070] It should be noted that the throttling device in this paper is an electronic expansion valve or a series connection of a solenoid valve and a capillary tube. To achieve accurate control of refrigerant flow, the first throttling device 16, the second throttling device 17, the refrigeration throttling device 10, and the heating throttling device 11 are all electronic expansion valves.

[0071] To achieve better heat dissipation effect, the application also proposes a heat dissipation control method, which designs the inflection point temperature for different working modes, dynamically adjusts the heat dissipation strategy by accurately matching the temperature characteristics of the condensation side heat exchange medium of each mode, solves the adaptability problem of the traditional single heat dissipation scheme under high / low temperature working conditions, ensures the temperature stability of the variable frequency drive module under all scenarios, and significantly enhances the reliability and energy efficiency level of the unit.

[0072] As shown in Figure 1 The control logic of the heat dissipation control method is as follows:

[0073] Obtain the working mode of the variable frequency heat pump unit and the condensation side heat exchange medium temperature of the refrigerant circulation loop;

[0074] Compare the condensation side heat exchange medium temperature with the set inflection point temperature corresponding to the current working mode;

[0075] If the condensation side heat exchange medium temperature > the set inflection point temperature, it means that the high-pressure refrigerant temperature is high, and the heat dissipation effect of the variable frequency drive module is poor, so the first heat dissipation strategy mainly adjusted by the first throttling device 16 is executed to actively enhance the heat dissipation through the cooling effect of the first branch;

[0076] If the condensation side heat exchange medium temperature < the set inflection point temperature, the second heat dissipation strategy mainly adjusted by the second throttling device 17 is executed to perform normal heat dissipation or auxiliary first branch heat dissipation on the variable frequency drive module.

[0077] It should be understood that the condensation side heat exchange medium temperature refers to the temperature of the heat exchange medium in the condenser that exchanges heat with the refrigerant. If the condenser is an air conditioning water heat exchanger or a hot water heat exchanger (usually a tube shell heat exchanger), the condensation side heat exchange medium is water, i.e. the condensation side heat exchange medium temperature is the water temperature. If the condenser is an outdoor heat exchanger (usually a fin heat exchanger), the condensation side heat exchange medium is air, i.e. the condensation side heat exchange medium temperature is the ambient temperature. In addition, each mode is provided with its corresponding set inflection point temperature to distinguish high temperature working conditions and low temperature working conditions, and to achieve more accurate dynamic adjustment of the heat dissipation strategy.

[0078] Specifically, in some preferred embodiments of the application, the first heat dissipation strategy includes:

[0079] Obtain the actual temperature of the variable frequency drive module 15;

[0080] When the actual temperature ≥ the set temperature B, it means that the temperature of the variable frequency drive module is too high, and the refrigerant flow needs to be increased, so the opening of the first throttling device 16 is increased, for example, 10B is increased every 10 seconds;

[0081] When the actual temperature < the set temperature B, it indicates that the temperature of the variable frequency driving module is moderate, the first throttling device 16 is controlled to maintain the set initial opening degree, the opening degree of the second throttling device 17 is adjusted according to the set slow speed mode, and the second throttling device 17 is used to supplement heat dissipation.

[0082] This design can realize accurate heat dissipation under high-temperature working conditions, quickly increase the refrigerant flow when the IPM temperature is relatively high, strengthen the heat dissipation capacity, and solve the problem of overheating of the module caused by insufficient heat dissipation of the refrigerant under high temperature; when the IPM temperature is moderate, the initial opening degree of the first throttling device 16 is maintained, and the heat dissipation is supplemented only through the second throttling device 17, so as to balance the heat dissipation efficiency and the reliability of the unit.

[0083] In some preferred embodiments of the present application, the second heat dissipation strategy comprises:

[0084] The actual temperature of the variable frequency driving module is obtained;

[0085] When the actual temperature ≥ the set temperature B1, it indicates that the temperature of the variable frequency driving module 15 is relatively high, the opening degree of the second throttling device 17 needs to be increased, and if the second throttling device 17 is opened to the maximum opening degree, the opening degree of the first throttling device 16 is increased;

[0086] When the actual temperature ≤ the set temperature A1, it indicates that the temperature of the variable frequency driving module 15 is relatively low, the first throttling device 16 is closed, the opening degree of the second throttling device 17 is adjusted according to the set slow speed mode, and the variable frequency driving module 15 is conventionally heat-dissipated through the second branch;

[0087] When the set temperature A1 < the actual temperature < the set temperature B1, it indicates that the temperature of the variable frequency driving module 15 is moderate, the first throtting device 16 is controlled to maintain the current opening degree, the opening degree of the second throttling device 17 is adjusted according to the set fast speed mode, and the heat dissipation is performed through the second branch to assist the first branch.

[0088] This design can realize accurate heat dissipation under low-temperature working conditions, realize hierarchical adjustment according to the actual temperature of the IPM, realize accurate matching of the heat dissipation amount and the heat load, avoid insufficient heat dissipation, prevent excessive heat dissipation, and protect the stability of the IPM temperature.

[0089] On the basis of the above heat dissipation strategy, in some feasible embodiments of the present application, the set slow speed mode comprises:

[0090] The actual superheat degree of the heat dissipation pipeline, i.e. the temperature difference between the outlet end and the inlet end of the heat dissipation pipeline, is obtained;

[0091] When the actual superheat degree > the set superheat degree ΔC1, it indicates that the heat dissipation load of the variable frequency driving module 15 is relatively large, the refrigerant flow needs to be increased, and the opening degree of the second throttling device 17 is increased every time interval set time E1;

[0092] When the actual superheat < the set superheat ΔD1, it indicates that the heat dissipation load of the variable frequency drive module 15 is small, the refrigerant flow needs to be reduced, and the opening of the second throttling device 17 is closed every interval set time E1;

[0093] When the set temperature ΔD1 < the actual temperature < the set temperature ΔC1, it indicates that the heat dissipation load of the variable frequency drive module 15 is moderate, the current refrigerant flow is maintained, and the opening of the second throttling device 17 is maintained.

[0094] The design reduces the adjustment frequency through a longer set time, reduces the energy loss caused by frequent valve action, can maintain the basic heat dissipation requirement, avoids the decline of the unit stability caused by excessive sensitive adjustment, and is suitable for scenes with gentle heat dissipation load change.

[0095] In some feasible embodiments of the present application, the set fast mode includes:

[0096] The actual superheat of the heat dissipation pipeline is obtained, that is, the temperature difference between the outlet end and the inlet end of the heat dissipation pipeline;

[0097] When the actual superheat > the set superheat ΔC2, it indicates that the heat dissipation load of the variable frequency drive module 15 is large, the refrigerant flow needs to be increased, and the opening of the second throttling device 17 is increased every interval set time E2;

[0098] When the actual superheat < the set superheat ΔD2, it indicates that the heat dissipation load of the variable frequency drive module 15 is small, the refrigerant flow needs to be reduced, and the opening of the second throttling device 17 is closed every interval set time E2;

[0099] When the set temperature ΔD2 < the actual temperature < the set temperature ΔC2, it indicates that the heat dissipation load of the variable frequency drive module 15 is moderate, the current refrigerant flow is maintained, and the opening of the second throttling device 17 is maintained.

[0100] Wherein, the set time E2 < the set time E1.

[0101] The design realizes more timely superheat response through a shorter set time, the opening adjustment interval of the second throttling device 17 is shorter when the actual superheat deviates from the set value, the heat dissipation load deviation can be quickly corrected, the overshoot or under-regulation of the IPM temperature due to adjustment delay is avoided, the IPM temperature is restored to be stable in a short time, and the design is suitable for scenes with heat dissipation load fluctuation.

[0102] It should be understood that when the opening of the second throttling device 17 needs to be closed, if the opening of the second throttling device 17 has reached the minimum step and the first throttling device 16 has not reached the minimum step, the opening of the first throttling device 16 is closed to reduce the refrigerant amount and avoid the IPM temperature being too low.

[0103] As Figure 1As shown, for the convenience of understanding, one application example of the present application is taken as an example to be described in detail.

[0104] Refrigeration mode / cooling and heating water mode

[0105] When the ambient temperature is higher than the set inflection point temperature of the refrigeration mode / cooling and heating water mode -40℃, due to the high temperature of the high-pressure refrigerant, the heat dissipation effect of the IPM is poor, and the first heat dissipation strategy is executed-mainly adjusted by the first throttling device 16:

[0106] When the actual temperature of the IPM is greater than or equal to the set temperature B, the opening of the first throttling device 16 is increased by 10B every 10 seconds until the maximum opening;

[0107] When the actual temperature of the IPM is less than the set temperature B, the first throttling device 16 maintains the set initial opening, and the opening of the second throttling device 17 is adjusted according to the set slow mode to obtain the actual superheat degree of the heat dissipation pipeline. When the actual superheat degree is greater than 3℃, the opening of the second throttling device 17 is increased by 5B every 60 seconds until the maximum opening. When the actual superheat degree is between 1-3℃, the opening of the second throttling device 17 is maintained. When the actual superheat degree is less than 1℃, the opening of the second throttling device 17 is reduced by 5B every 60 seconds until the minimum step number. If the superheat degree still cannot be met, the opening of the first throttling device 16 is reduced by 5B every 30 seconds.

[0108] When the ambient temperature is lower than the set inflection point temperature of the refrigeration mode / cooling and heating water mode -40℃, the liquid refrigerant can better dissipate heat for the IPM, and the second heat dissipation strategy is executed-mainly adjusted by the second throttling device 17:

[0109] When the actual temperature of the IPM is greater than or equal to the set temperature B1, the opening of the second throttling device 17 is increased by 10B every 30 seconds until the maximum opening. If the actual temperature still cannot be met, the first throttling device 16 is opened, and the opening is increased by 5B every 10 seconds.

[0110] When the actual temperature of the IPM is less than or equal to the set temperature A1, the first throttling device 16 is closed, and the opening of the second throttling device 17 is adjusted according to the set slow mode to obtain the actual superheat degree of the heat dissipation pipeline. When the actual superheat degree is greater than 3℃, the opening of the second throttling device 17 is increased by 5B every 60 seconds until the maximum opening. When the actual superheat degree is between 1-3℃, the opening of the second throttling device 17 is maintained. When the actual superheat degree is less than 1℃, the opening of the second throttling device 17 is reduced by 5B every 60 seconds until the minimum step number.

[0111] When the actual temperature of the IPM is between the set temperature A1 and the set temperature B1, the first throttling device 16 maintains the current opening degree, the opening degree of the second throttling device 17 is adjusted according to the set fast mode, when the actual overheat degree is greater than 5℃, the opening degree of the second throttling device 17 is increased by 5B every 30 seconds until the maximum opening degree; when the actual overheat degree is between 3-5℃, the opening degree of the second throttling device 17 is maintained; when the actual overheat degree is less than 3℃, the opening degree of the second throttling device 17 is decreased by 5B every 30 seconds until the minimum step.

[0112] Heating mode / hot water mode / heating and hot water mode

[0113] When the water temperature is higher than the set inflection point temperature of the heating mode / hot water mode / heating and hot water mode, 40℃, because the high-pressure refrigerant temperature is high, the heat dissipation effect on the IPM is poor, the first heat dissipation strategy is executed, that is, the first throttling device 16 is mainly adjusted:

[0114] When the actual temperature of the IPM is greater than or equal to the set temperature B, the opening degree of the first throttling device 16 is increased by 10B every 10 seconds until the maximum opening degree.

[0115] When the actual temperature of the IPM is less than the set temperature B, the first throttling device 16 maintains the set initial opening degree, the opening degree of the second throttling device 17 is adjusted according to the set slow mode, the actual overheat degree of the heat dissipation pipeline is obtained, when the actual overheat degree is greater than 3℃, the opening degree of the second throttling device 17 is increased by 5B every 60 seconds until the maximum opening degree; when the actual overheat degree is between 1-3℃, the opening degree of the second throttling device 17 is maintained; when the actual overheat degree is less than 1℃, the opening degree of the second throttling device 17 is decreased by 5B every 60 seconds until the minimum step, if the overheat degree still cannot be satisfied, the opening degree of the first throttling device 16 is decreased by 5B every 30 seconds.

[0116] When the water temperature is lower than the set inflection point temperature of the heating mode / hot water mode / heating and hot water mode, 40℃, the liquid refrigerant can better dissipate heat for the IPM, the second heat dissipation strategy is executed, that is, the second throttling device 17 is mainly adjusted:

[0117] When the actual temperature of the IPM is greater than or equal to the set temperature B1, the opening degree of the second throttling device 17 is increased by 10B every 30 seconds until the maximum opening degree, when the actual temperature still cannot be satisfied, the first throttling device 16 is opened, and the opening degree is increased by 5B every 10 seconds.

[0118] When the actual temperature of the IPM is less than or equal to the set temperature A1, the first throttling device 16 is closed, the opening of the second throttling device 17 is adjusted according to the set slow mode, the actual overheat degree of the heat dissipation pipeline is obtained, when the actual overheat degree is greater than 3℃, the opening of the second throttling device 17 is increased by 5B every 60 seconds until the maximum opening; when the actual overheat degree is between 1-3℃, the opening of the second throttling device 17 is maintained; when the actual overheat degree is less than 1℃, the opening of the second throttling device 17 is decreased by 5B every 60 seconds until the minimum opening;

[0119] When the actual temperature of the IPM is between the set temperature A1 and the set temperature B1, the first throttling device 16 maintains the current opening, the opening of the second throttling device 17 is adjusted according to the set fast mode, when the actual overheat degree is greater than 5℃, the opening of the second throttling device 17 is increased by 5B every 30 seconds until the maximum opening; when the actual overheat degree is between 3-5℃, the opening of the second throttling device 17 is maintained; when the actual overheat degree is less than 3℃, the opening of the second throttling device 17 is decreased by 5B every 30 seconds until the minimum opening.

[0120] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. When the terms "including," "comprising," "having," and the like are used in the specification, these terms are intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional term in a claim. The action, step, etc. order of the methods and processes shown in the specification and figures can be performed in any order unless otherwise specifically noted, e.g., where a process is described as occurring sequentially with another process, the processes can be performed in parallel or concurrently. Also, the various figures can not be drawn to scale since they are merely intended to conceptually illustrate the features of the embodiments. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to "a component" or "the component" can include a plurality of such components, and so forth.

[0121] Techniques, methods, and apparatus known to the relevant skilled artisan can not be discussed in detail, but where appropriate, the described techniques, methods, and apparatus should be considered as part of the specification. In all examples shown and discussed herein, any specific values should be interpreted merely as examples, and not as a limitation. Thus, other examples of example embodiments can have different values. It should be noted that like reference numerals and letters in the various figures indicate like items, and therefore, once an item is defined in one figure, it need not be discussed further in subsequent figures.

[0122] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A heat dissipation control method for a variable frequency heat pump unit, wherein the variable frequency heat pump unit comprises: A refrigerant circulation loop and a variable frequency drive module, the refrigerant circulation loop is connected by a compressor, a heat exchanger combination, a liquid accumulator, and a gas-liquid separator, the heat exchanger combination comprises three heat exchangers, and at least two of the heat exchangers participate in the refrigerant circulation of the refrigerant circulation loop; The variable frequency drive module is provided with a heat dissipation pipeline, an outlet end of the heat dissipation pipeline is connected to a suction side of the compressor, an inlet end of the heat dissipation pipeline is communicated with a liquid storage cavity of the liquid accumulator through a first branch and a second branch, the first branch is provided with a cooling pipe section located inside the gas-liquid separator, a first throttling device is installed at an outlet side of the cooling pipe section, the second branch is located outside the gas-liquid separator, and a second throttling device is installed on the second branch, the opening degrees of the first throttling device and the second throttling device are adjustable and work cooperatively. The heat dissipation control method comprises: obtaining a working mode of the variable frequency heat pump unit and a condensing side heat exchange medium temperature of the refrigerant circulation loop; comparing the condensing side heat exchange medium temperature with a set inflection point temperature corresponding to the current working mode; if the condensing side heat exchange medium temperature is greater than the set inflection point temperature, executing a first heat dissipation strategy mainly adjusted by the first throttling device; if the condensing side heat exchange medium temperature is less than the set inflection point temperature, executing a second heat dissipation strategy mainly adjusted by the second throttling device.

2. The heat radiation control method according to claim 1, wherein The three heat exchangers are a first heat exchanger, a second heat exchanger, and a third heat exchanger, and an exhaust side of the compressor can be switched to connect a first end of any one of the heat exchangers; a second end of the first heat exchanger is connected to the liquid accumulator through a first outlet pipe and a first inlet pipe; a second end of the second heat exchanger is connected to the liquid accumulator through a second outlet pipe; a second end of the third heat exchanger is connected to the liquid accumulator through a third outlet pipe and a third inlet pipe; wherein each outlet pipe is provided with a control valve allowing refrigerant to flow to the liquid accumulator, and each inlet pipe is provided with a throttling device.

3. The heat radiation control method according to claim 2, wherein The second end of the second heat exchanger is also connected to the liquid accumulator through a second inlet pipe.

4. The heat radiation control method according to claim 2, wherein The first heat exchanger is an air conditioning water heat exchanger, the second heat exchanger is a hot water heat exchanger, the third heat exchanger is an outdoor heat exchanger, and the working mode of the variable frequency heat pump unit comprises at least one of a refrigeration mode, a heating mode, a hot water mode, a refrigeration and hot water mode, and a heating and hot water mode.

5. The heat dissipation control method according to any one of claims 1 to 4, characterized by, The first throttling device and the second throttling device are both electronic expansion valves.

6. The heat radiation control method according to claim 1, wherein The first heat dissipation strategy comprises: obtaining an actual temperature of the variable frequency drive module; when the actual temperature is greater than or equal to a set temperature B, increasing the opening degree of the first throttling device; when the actual temperature is less than the set temperature B, maintaining the first throttling device at a set initial opening degree and adjusting the opening degree of the second throttling device in a set slow mode.

7. The heat radiation control method according to claim 1, wherein The second heat dissipation strategy comprises: obtaining an actual temperature of the variable frequency drive module; when the actual temperature is greater than or equal to a set temperature B1, increasing the opening degree of the second throttling device, and if the second throttling device is opened to a maximum opening degree, increasing the opening degree of the first throttling device. When the actual temperature ≤ the set temperature A1, the first throttling device is closed, and the opening of the second throttling device is adjusted according to a set slow mode; When the set temperature A1 < the actual temperature < the set temperature B1, the first throttling device is controlled to maintain the current opening, and the opening of the second throttling device is adjusted according to a set fast mode.

8. The heat radiation control method according to claim 7, wherein The set slow mode comprises: acquiring the actual overheat degree of the heat dissipation pipeline; When the actual overheat degree > the set overheat degree ΔC1, the opening of the second throttling device is increased every set time E1; When the actual overheat degree < the set overheat degree ΔD1, the opening of the second throttling device is decreased every set time E1; When the set temperature ΔD1 < the actual temperature < the set temperature ΔC1, the opening of the second throttling device is maintained.

9. The heat radiation control method according to claim 8, wherein The set fast mode comprises: acquiring the actual overheat degree of the heat dissipation pipeline; When the actual overheat degree > the set overheat degree ΔC2, the opening of the second throttling device is increased every set time E2; When the actual overheat degree < the set overheat degree ΔD2, the opening of the second throttling device is decreased every set time E2; When the set temperature ΔD2 < the actual temperature < the set temperature ΔC2, the opening of the second throttling device is maintained. Wherein, the set time E2 < the set time E1.

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