Starting control method of heat pump system and heat pump system

Abstract

The invention relates to a starting control method of a heat pump system and the heat pump system.The starting control method comprises the steps that the operation time of a compressor on a low-frequency platform is dynamically adjusted according to the standing duration of the compressor, the operation strategy of the compressor in the initial starting stage is optimized, and the heat pump system can still ensure that lubricating oil stably returns to a crankcase in the low-temperature environment; the efficiency is improved on the basis of effectively avoiding the liquid impact and oil shortage phenomena of the compressor; the temperature influence factor is introduced to achieve self-adaptive adjustment of the correction value, under different working conditions, the operation duration of the compressor on a low-frequency platform can accurately guarantee oil return of the compressor, and based on an environment coupling correction mechanism, the higher adaptive capacity can be shown under the extreme temperature condition.

Description

Technical Field

[0001] This invention relates to the field of heat pump control technology, and in particular to a start-up control method for a heat pump system and a heat pump system. Background Technology

[0002] Oil shortage during the initial startup of a heat pump system is one of the most troublesome hidden dangers in low-temperature, long-pipe, and variable-frequency heat pump systems.

[0003] The existing soft-start control mode uses frequency-increase oil return: during the initial startup of the compressor, the compressor frequency is increased to 55Hz-65Hz for 30-60 seconds to carry oil back from the evaporator to the compressor via high flow rate, before being reduced to the target frequency. However, at low temperatures, due to the low evaporation pressure, rapid frequency increase can lead to liquid slugging in the compressor, potentially damaging it. Furthermore, under high temperature and high humidity conditions, frequency increase can easily trigger overheat protection, causing frequent start-stop cycles. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a start-up control method for a heat pump system. This start-up control method corrects the low-frequency operating time based on the compressor's resting time, bringing the oil from the evaporator back to the crankcase and reducing the risk of compressor oil shortage.

[0005] A method for starting up a heat pump system includes the following steps:

[0006] S10: Obtain the compressor's resting time at the compressor start-up time. Determine the resting time Is it less than the resting equilibrium time? : If so, based on the settling time. Calculate the correction value for the runtime of the first frequency platform ; If not, it depends on the settling time. Calculate the correction value for the runtime of the first frequency platform ; S20: Based on the correction value Setting the runtime of the first frequency platform Make corrections to obtain the target runtime. ; S30: Control the compressor to run at the set first frequency ramp rate △F1 to the first frequency platform, and maintain the target running time on the first frequency platform. Then, according to the set second up-rate ΔF2, it runs to the second frequency platform or target frequency.

[0007] Furthermore, when using the settling time Calculate the correction value for the runtime of the first frequency platform At that time, the correction value satisfy:

[0008] When using static balancing time Calculate the correction value for the runtime of the first frequency platform At that time, the correction value satisfy:

[0009] Here, ceil is the floor function.

[0010] Furthermore, the target runtime satisfy:

[0011] in, This indicates the set runtime of the first frequency platform. This indicates a correction value.

[0012] Furthermore, the ambient temperature is obtained, the ambient temperature range is determined, and the correction value is adjusted according to the temperature influence factor corresponding to different ambient temperature ranges. Perform ambient temperature correction to obtain the corrected value for the coupled ambient temperature. ;

[0013] Where ki is the temperature influence factor of the corresponding ambient temperature range, and k1, k2, k3, and k4 correspond to the first ambient temperature range, the second ambient temperature range, the third ambient temperature range, and the fourth ambient temperature range, respectively. k1, k2, k3, and k4 are determined according to experimental calibration.

[0014] Furthermore, The first ambient temperature range is <-15℃, and the temperature influence factor is k1; The second ambient temperature range is [-15℃, 10℃), and the temperature influence factor is k2; The third ring temperature range is [10℃, 35℃), and the temperature influence factor is k3; The fourth temperature range is ≥35℃, and the temperature influence factor is k4; The condition is satisfied that k1 > k2 > k3 > k4 > 1.

[0015] Furthermore, the compressor also includes the following controls during operation on the first frequency platform: Obtain oil separator outlet pressure and inhalation pressure Calculate the pressure difference Determine the pressure difference Whether it is stable within the differential pressure range: If so, it is determined that the compressor is not short of oil, and it runs to the second frequency platform or target frequency according to the set second frequency increase rate △F2. If not, the compressor frequency will be maintained at the first frequency platform until the target running time is reached. Then, based on the set second up-rate ΔF2, it runs to the second frequency platform or target frequency.

[0016] Furthermore, the differential pressure range is set to [0.05, 0.15] MPa.

[0017] Furthermore, the compressor's operating time on the first frequency platform has reached the target operating time. ; If pressure difference If the pressure remains below 0.05 MPa within the set time period, it is determined that the return oil pipe is blocked or the oil pump head is insufficient, and an early warning is activated. If pressure difference If the pressure remains above 0.2 MPa for a set period of time, it is determined that the normally open return solenoid valve or the check valve has failed, and an early warning is triggered.

[0018] Furthermore, the first upsampling rate ΔF1 is set to 1~2Hz / s, and the first frequency plateau is set to 30~45Hz; The second upsampling rate ΔF2 is set to 3~4Hz / s, and the second frequency plateau is set to 55~65Hz.

[0019] Compared to existing technologies, this invention dynamically adjusts the compressor's operating time on the low-frequency platform by adjusting the compressor's resting time, optimizing the compressor's initial start-up operating strategy. This ensures that the heat pump system can still guarantee a stable return of lubricating oil to the crankcase in low-temperature environments, effectively avoiding compressor liquid slugging and oil shortage, while improving efficiency. By introducing a temperature influence factor to achieve adaptive adjustment of the correction value, the compressor's operating time on the low-frequency platform can be precisely guaranteed to ensure oil return under different operating conditions. Based on the environmental coupling correction mechanism, it exhibits stronger adaptability under extreme temperature conditions.

[0020] Meanwhile, the present invention also provides a heat pump system with start-up control, including a compressor, a four-way valve, a condenser, a throttle valve, an evaporator, and a gas-liquid separator connected in sequence through a refrigerant circulation pipeline, an oil return monitoring module for monitoring the oil return status of the compressor, and a controller electrically and / or communicatively connected to the compressor and the oil return monitoring module; wherein, the oil return monitoring module includes a first pressure sensor and a second pressure sensor, the first pressure sensor being located at the oil outlet of the gas-liquid separator for measuring the oil outlet pressure, and the second pressure sensor being located at the suction port of the compressor for measuring the suction pressure; the controller implements the above-described start-up control method for the heat pump system.

[0021] Compared with the prior art, the beneficial effects of the heat pump system with start-up control provided by the present invention are the same as those of the heat pump system start-up control method described above, and will not be repeated here. Attached Figure Description

[0022] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the heat pump system of the present invention; Figure 2 This is a flowchart of the start-up control method for the heat pump system of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. The described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0025] Please see Figure 1 The heat pump system with start-up control described in this invention includes a compressor 10, a four-way valve 20, a condenser 30, a throttle valve 40, an evaporator 50, and a gas-liquid separator 60, which are circulated through refrigerant pipelines, an oil return monitoring module 70 for monitoring the oil return status of the compressor, and a controller (not shown) that is communicatively connected to the compressor 10 and the oil return monitoring module 70.

[0026] The oil return monitoring module 70 is used to detect the oil return status of the compressor 10 in real time, and includes a first pressure sensor 71 and a second pressure sensor 72.

[0027] The first pressure sensor 71 is installed at the oil outlet of the gas-liquid separator 60 and is used to measure the oil outlet pressure. And in real time, the oil separator outlet pressure Transmitted to the controller.

[0028] The second pressure sensor 72 is located at the suction port of the compressor 10 and is used to measure the suction pressure. And inhalation pressure in real time Transmitted to the controller.

[0029] The controller corrects the compressor's first frequency platform running time T1 based on the received compressor resting time T, and dynamically adjusts the compressor's running time on the first frequency platform in conjunction with the compressor's oil return status. This ensures that the heat pump system can still ensure stable return of lubricating oil to the crankcase in low-temperature environments, effectively avoiding compressor liquid slugging and oil shortage, while improving efficiency.

[0030] Furthermore, the heat pump system with start-up control also includes an ambient temperature sensor to detect the ambient temperature of the environment where the heat pump system is located and transmit the temperature information to the controller.

[0031] Please see Figure 2 The controller implements the start-up control of the heat pump system in the following manner, specifically including the following steps.

[0032] S10: Obtain the compressor's resting time at the compressor start-up time. Determine the resting time Is it less than the resting equilibrium time? : If so, based on the settling time. Calculate the correction value for the runtime of the first frequency platform ; If not, it depends on the settling time. Calculate the correction value for the runtime of the first frequency platform .

[0033] The settling time T satisfies:

[0034] in, Indicates the compressor start-up time. This indicates the compressor shutdown time closest to the startup time.

[0035] The static equilibrium time The time required for the migration of lubricating oil and refrigerant together towards the evaporator and the bottom of the return pipe to reach equilibrium over time is determined by the variation in the amount of migration over time. In this embodiment, it is set to 48 hours.

[0036] Correction value for the runtime of the first frequency platform satisfy: or

[0037] Here, ceil is the floor function.

[0038] S20: Based on the correction value Setting the runtime of the first frequency platform Make corrections to obtain the target runtime. .

[0039] The target runtime satisfy: .

[0040] Furthermore, the ambient temperature is obtained, the ambient temperature range is determined, and the correction value is adjusted according to the temperature influence factor corresponding to different ambient temperature ranges. Perform ambient temperature correction to obtain the corrected value for the coupled ambient temperature. .

[0041] In practice, this includes four ambient temperature zones. The first ambient temperature range is <-15℃, and the temperature influence factor is k1; The second ambient temperature range is [-15℃, 10℃), and the temperature influence factor is k2; The third ring temperature range is [10℃, 35℃), and the temperature influence factor is k3; The fourth temperature range is ≥35℃, and the temperature influence factor is k4; k1, k2, k3, and k4 are determined by experimental calibration and satisfy k1 > k2 > k3 > k4 > 1.

[0042] Correction value for coupling ambient temperature satisfy:

[0043] Where ki is the temperature influence factor of the corresponding ring temperature range, and k1, k2, k3, and k4 correspond to the first ring temperature range, the second ring temperature range, the third ring temperature range, and the fourth ring temperature range, respectively.

[0044] Then the target runtime satisfy: .

[0045] Determining the target runtime depends not only on the heat pump system's resting time but also on the impact of ambient temperature on oil return. By introducing a temperature influence factor, adaptive adjustment of the correction value is achieved, ensuring excellent oil return control under various operating conditions. This environmentally coupled correction mechanism exhibits stronger adaptability under extreme temperature conditions. The final calculated target runtime fully integrates the effects of lubricating oil resting characteristics and the external thermodynamic environment, enabling refined control of the operating strategy.

[0046] S30: Control the compressor to run at the set first frequency ramp rate △F1 to the first frequency platform, and maintain the target running time on the first frequency platform. Then, according to the set second up-rate ΔF2, it runs to the second frequency platform or target frequency.

[0047] Among them, the first upsampling rate ΔF1 is set to 1~2Hz / s, and the first frequency plateau is set to 30~45Hz; The second upsampling rate ΔF2 is set to 3~4Hz / s, and the second frequency plateau is set to 55~65Hz.

[0048] By employing a segmented frequency ramp-up control strategy, oil pressure fluctuations caused by sudden changes in compressor speed are effectively avoided, ensuring stable oil return. During the initial frequency plateau period, the heat pump system completes oil circuit circulation balancing, ensuring sufficient lubrication within the compressor before entering the high-load operation phase, thereby improving overall machine reliability and energy efficiency.

[0049] Furthermore, the compressor also includes the following controls during operation on the first frequency platform: Obtain oil separator outlet pressure and inhalation pressure Calculate the pressure difference Determine the pressure difference Whether it is stable within the differential pressure range: If so, it is determined that the compressor is not short of oil, and it runs to the second frequency platform or target frequency according to the set second frequency increase rate △F2. If not, the compressor frequency will be maintained at the first frequency platform until the target running time is reached. Then, based on the set second up-rate ΔF2, it runs to the second frequency platform or target frequency.

[0050] The pressure difference satisfy .

[0051] The pressure difference is said to stabilize within the differential pressure range, that is, within a set time period, such as 30 seconds or 1 minute. The pressure fluctuates within the differential pressure range. The differential pressure range is set according to the operating conditions of the heat pump system. In this embodiment, the differential pressure range is set to [0.05, 0.15] MPa.

[0052] Furthermore, the compressor's operating time on the first frequency platform has reached the target operating time. If the pressure difference If the pressure remains below 0.05 MPa within the set time period, it is determined that the return oil pipe is blocked or the oil pump head is insufficient, and an early warning is activated. If pressure difference If the pressure remains above 0.2 MPa for a set period of time, it is determined that the normally open return solenoid valve or the check valve has failed, and an early warning is triggered.

[0053] Compared to existing technologies, this invention dynamically adjusts the compressor's operating time on the low-frequency platform by adjusting the compressor's resting time, optimizing the compressor's initial start-up operating strategy. This ensures that the heat pump system can still guarantee a stable return of lubricating oil to the crankcase in low-temperature environments, effectively avoiding compressor liquid slugging and oil shortage, while improving efficiency. By introducing a temperature influence factor to achieve adaptive adjustment of the correction value, the compressor's operating time on the low-frequency platform can be precisely guaranteed to ensure oil return under different operating conditions. Based on the environmental coupling correction mechanism, it exhibits stronger adaptability under extreme temperature conditions.

[0054] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0055] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0056] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A method of starting control of a heat pump system, characterized by, The method comprises the following steps: S10: At the starting moment of the compressor, the static standing time length of the compressor is acquired ; it is judged whether the static standing time length is less than the static balance time length : If yes, according to the standing time calculate the correction value of the first frequency platform running time ; If no, according to the length of static balance Calculate the correction value of the first frequency platform running time ; S20: correct the value according to the correction value the set duration of the first frequency platform correct the value to obtain the target duration ; S30: control the compressor to run at a set first frequency increasing rate ΔF1 to a first frequency platform, and keep the target running time length at the first frequency platform After that, run to a second frequency platform or a target frequency according to a set second frequency increasing rate ΔF2.

2. The startup control method of a heat pump system according to claim 1, characterized by, When the static standing time length The correction value of the first frequency platform running time length is calculated The correction value Satisfies: When a static balance is adopted The correction value of the first frequency platform running time is calculated The correction value Satisfies: Wherein, ceil is the upward rounding function.

3. The startup control method of a heat pump system according to claim 2, characterized by, The target running time Satisfies: wherein represents the set runtime of the first frequency plateau, represents a correction value.

4. The startup control method of a heat pump system according to claim 3, characterized by, An ambient temperature is acquired, a ring temperature interval in which the ambient temperature is located is determined, and a correction value is corrected according to a temperature influence factor corresponding to different ring temperature intervals A ring temperature correction is performed to obtain a correction value coupled with the ambient temperature ; Wherein, ki is the temperature influence factor corresponding to the ring temperature interval, k1, k2, k3, k4 correspond to the first ring temperature interval, the second ring temperature interval, the third ring temperature interval, the fourth ring temperature interval respectively, and the k1, k2, k3, k4 are determined according to the experiment calibration.

5. The starting control method of the heat pump system according to claim 4, characterized in that, The first ring temperature interval is <-15℃, and the temperature influence factor is k1. The second ring temperature interval is [-15℃, 10℃), and the temperature influence factor is k2. The third ring temperature interval is [10℃, 35℃), and the temperature influence factor is k3. The fourth ring temperature interval is ≥35℃, and the temperature influence factor is k4. k1>k2>k3>k4>1 is satisfied.

6. The startup control method of a heat pump system according to claim 1, characterized by During the operation of the compressor at the first frequency platform, the following control is further included: acquiring the oil outlet pressure and the suction pressure , calculating the pressure difference , determining whether the pressure difference is stable in the pressure difference range If yes, it is determined that the compressor is not short of oil, and the second frequency platform or the target frequency is operated according to the set second frequency increasing rate △F2. If not, the compressor frequency is continuously maintained at the first frequency plateau until the operation time reaches the target operation time After that, a second frequency ramping rate ΔF2 is set and the operation is continued to the second frequency plateau or the target frequency.

7. The startup control method of a heat pump system according to claim 6, characterized by, The pressure difference interval is set to [0.05, 0.15] MPa.

8. The startup control method of a heat pump system according to claim 7, characterized by, the compressor has reached a target run length of operation at the first frequency plateau ; If the pressure difference If the pressure difference is still below 0.05 MPa for a set period of time, it is determined that the oil return pipe is blocked or the oil pump pressure head is insufficient, and a warning is started. If the pressure difference If the pressure difference is continuously higher than 0.2 MPa for a set period of time, it is determined that the oil return solenoid is always open or the one-way valve is malfunctioning, and a warning is initiated.

9. The startup control method of a heat pump system according to claim 1, characterized by, The set first frequency increasing rate △F1 is 1-2 Hz / s, and the first frequency platform is 30-45 Hz. The set second frequency increasing rate △F2 is 3-4 Hz / s, and the second frequency platform is 55-65 Hz.

10. A heat pump system with start-up control, comprising a compressor, a four-way valve, a condenser, a throttle valve, an evaporator and a gas-liquid separator connected in sequence by a refrigerant circulation pipeline, an oil return monitoring module for monitoring the oil return state of the compressor, and a controller electrically connected and / or communicatively connected with the compressor and the oil return monitoring module; wherein, The oil return monitoring module comprises a first pressure sensor and a second pressure sensor, the first pressure sensor is arranged at the oil separation outlet of the gas-liquid separator and used for measuring the oil separation outlet pressure, and the second pressure sensor is arranged at the suction port of the compressor and used for measuring the suction pressure. The controller realizes the starting control method of the heat pump system according to any one of claims 1-9.

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