阅读说明：本技术 用于冷凝机组的预保护方法以及冷凝机组 (Pre-protection method for condensing unit and condensing unit ) 是由 杨继坤 于 2020-03-03 设计创作，主要内容包括：本发明提供一种用于冷凝机组的预保护方法。冷凝机组包括压缩机以及包括具有容量调节功能的数码压缩机以及控制数码压缩机的加载/卸载切换的切换元件。该预保护方法包括以下步骤：监测冷凝机组的工作参数的数值,将监测到的该工作参数的数值与该工作参数所对应的预定值进行比较,以及基于比较的结果来控制切换元件的动作以调节压缩机的最大允许加载时间百分比。此外,本发明还提供了储存有上述预保护程序的计算机可读介质和包括该计算机可读介质的控制器以及相应的冷凝机组。根据本发明的技术方案使得压缩机组能够在恶劣环境下保持良好运行。(The invention provides a pre-protection method for a condensing unit. The condensing unit comprises a compressor, a digital compressor with a capacity adjusting function and a switching element for controlling the loading/unloading switching of the digital compressor. The pre-protection method comprises the following steps: the method comprises the steps of monitoring the numerical value of the working parameter of the condensing unit, comparing the monitored numerical value of the working parameter with a preset value corresponding to the working parameter, and controlling the action of a switching element based on the comparison result to adjust the maximum allowable loading time percentage of the compressor. In addition, the invention also provides a computer readable medium stored with the pre-protection program, a controller comprising the computer readable medium and a corresponding condensing unit. According to the technical scheme of the invention, the compressor unit can keep good operation in severe environment.)

1. A pre-protection method for a condensing unit (100), the condensing unit comprising a digital compressor (110) with capacity modulation and a switching element (170) controlling the loading/unloading switching of the digital compressor, the pre-protection method comprising the steps of:

monitoring the value (P) of an operating parameter of the condensing unit_x)，

The monitored value of the working parameter is compared with a preset value (P) corresponding to the working parameter_px) Making a comparison, and

controlling an action of the switching element based on a result of the comparison to adjust a maximum allowable load time percentage (OCA) of the digital compressor.

2. The pre-protection method according to claim 1, wherein the operating parameter is a parameter directly or indirectly reflecting the magnitude of the condensing pressure of the condensing unit.

3. The pre-protection method of claim 2, wherein the operating parameter is one or more of a condensing pressure, a condensing temperature, and a compressor operating current of the condensing unit.

4. A pre-protection method according to any one of claims 1 to 3, wherein the predetermined value of the operating parameter comprises a first predetermined value (P)_px1) And a second predetermined value (P)_px2) The first predetermined value is greater than the second predetermined value.

5. The pre-protection method according to claim 4, wherein the operating parameter is given a first difference (d) when the value is greater than or equal to a corresponding first predetermined value₁) Decreasing the maximum allowed load time percentage, wherein the decreased maximum allowed load time percentage is not lower than a load time percentage lower limit value (OC) set for the digital compressor_min)。

6. The pre-protection method of claim 5,

the first difference (d)₁) Is a fixed value; or

The first difference (d)₁) Can be calculated by the following formula:

d₁＝(P_x-P_px1)×r₁

wherein, P_xIs the value of the working parameter;

P_px1a corresponding first predetermined value for the operating parameter;

r₁to reduce the coefficients.

7. The pre-protection method according to claim 4, wherein when the maximum allowed loading time percentage is less than a loading time percentage upper limit value (OC) set for the digital compressor_max) And the value of the operating parameter is less than a corresponding second predetermined value, by a second difference (d)₂) Increasing the maximum allowableA percentage of allowable load time, wherein the increased maximum percentage of allowable load time is not higher than the upper limit of the percentage of load time.

8. The pre-protection method of claim 7,

the second difference (d)₂) Is a fixed value; or

The second difference (d)₂) Can be calculated by the following formula:

d₂＝(P_px2-P_x)×r₂

wherein, P_xIs the value of the working parameter;

P_px2a corresponding second predetermined value for the operating parameter;

r₂to increase the coefficient.

9. The pre-protection method according to any one of claims 1 to 3, wherein the switching element is a solenoid valve.

10. A computer readable medium storing a program for pre-protecting a condenser unit, wherein the program when executed implements the steps of the pre-protection method according to any one of claims 1 to 9.

11. A controller (150) for pre-protecting a condensing unit comprising a digital compressor with capacity modulation function with a switching element capable of performing a load/unload switching of the digital compressor by performing a switching action, the digital compressor being set with an upper loading time percentage value and/or a lower loading time percentage value, the controller comprising:

a data storage unit (152) comprising the computer-readable medium of claim 10;

a data acquisition unit (154) that monitors and acquires data regarding the operating parameters and transmits the data to the data storage unit; and

a data processing unit (156) that reads the data in the data storage unit and executes the program in the computer readable medium, and then outputs a processing result to the digital compressor to adjust a maximum allowable load time percentage of the digital compressor.

12. A condensation train (100), wherein the condensation train comprises a controller (150) according to claim 11.

Technical Field

The present invention relates to the field of condensing units, and more particularly, to a method capable of pre-protecting a condensing unit, a computer readable medium including a program implementing the method, a controller including the computer readable medium, and a condensing unit including the controller.

Background

Condensing units are often used in cold chains such as display cases in convenience stores or supermarkets or cold stores to maintain the temperature of stored items in a relatively constant low temperature environment.

Generally, a condensing unit has a controller capable of controlling the start and stop of a compressor (here, a digital compressor having a capacity adjustment function) according to a relationship between a suction pressure of the compressor and a set value, and simultaneously adjusting an output capacity of the compressor through a solenoid valve. If the actual suction pressure is above the set point, the controller starts the compressor and increases the output capacity of the compressor (solenoid valve closed) until the compressor is at the maximum output percentage. If the actual suction pressure is below the set point, the controller decreases the output capacity of the compressor until the compressor operates at the lowest output percentage, and if the suction pressure is further decreased, the controller stops the operation of the compressor.

In practical applications, the inventor has noticed that in the case of a condensing unit operating in a poor environment, for example, in the case of adverse ventilation conditions, extreme environmental temperatures or dirty condensers, the condensing pressure will continue to rise, and once a nominal threshold is reached, the high-pressure safety switch will be triggered to open, causing a high-pressure alarm and shutdown. Such unexpected shutdown is disadvantageous in that it causes the temperature of the stored goods and food to rise, thereby affecting the storage quality, and may cause frequent start/stop of the compressor, which not only causes great fluctuation in the temperature of the refrigerated goods, but also easily causes wear of the machine, thereby shortening the service life of the machine.

It would therefore be desirable in the art to provide a condensing unit that performs well in harsh environments.

Disclosure of Invention

This summary is provided to introduce a general summary of the invention, not a full disclosure of the full scope of the invention or all of the features of the invention.

An object of the present invention is to provide a pre-protection method capable of reducing an unexpected shutdown of a compressor.

Another object of the present invention is to provide a condensing system that is more adaptable and more capable of coping with severe environments.

Another object of the present invention is to provide a condensing system capable of providing a more stable refrigerating effect.

It is a further object of the present invention to provide an improved condensing system in a simple, low cost manner.

In order to achieve at least one of the above objects, the present invention provides a pre-protection method for a condensing unit, a controller capable of performing a pre-protection function, and a condensing unit having the pre-protection function.

According to an aspect of the present invention, there is provided a pre-protection method for a condensing unit including a digital compressor having a capacity adjustment function and a switching element controlling a load/unload switching of the digital compressor, the pre-protection method including the steps of: the method comprises the steps of monitoring the numerical value of the working parameter of the condensing unit, comparing the monitored numerical value of the working parameter with a preset value corresponding to the working parameter, and controlling the action of a switching element based on the comparison result to adjust the maximum allowable loading time percentage of the digital compressor.

Preferably, the operating parameter is a parameter directly or indirectly reflecting the magnitude of the condensing pressure of the condensing unit. Optionally, the operating parameter is one or more of a condensing pressure, a condensing temperature and a compressor operating current of the condensing unit.

The preset values of the working parameters comprise a first preset value and a second preset value, and the first preset value is larger than the second preset value.

And when the numerical value of the working parameter is larger than or equal to the corresponding first preset value, reducing the maximum allowable loading time percentage by using a first difference value, wherein the reduced maximum allowable loading time percentage is not lower than the loading time percentage lower limit value set for the digital compressor. Wherein the first difference value is a fixed value; alternatively, the first difference can be calculated by the following formula:

d₁＝(P_x-P_px1)×r₁

wherein, P_xIs the value of the operating parameter;

P_px1a corresponding first predetermined value for the operating parameter;

r₁to reduce the coefficients.

And when the maximum allowable loading time percentage is smaller than the loading time percentage upper limit value set for the digital compressor and the numerical value of the working parameter is smaller than a corresponding second preset value, increasing the maximum allowable loading time percentage by a second difference value, wherein the increased maximum allowable loading time percentage is not higher than the loading time percentage upper limit value. Wherein the content of the first and second substances,

the second difference value is a fixed value; or

Second difference (d)₂) Can be calculated by the following formula:

d₂＝(P_px2-P_x)×r₂

wherein, P_xIs the value of the operating parameter;

P_px2a corresponding second predetermined value for the operating parameter;

r₂to increase the coefficient.

Wherein the switching element is a solenoid valve.

According to another aspect of the present invention, a computer readable medium is provided storing a program for pre-protecting a condensing unit, wherein the program when executed implements the steps of the pre-protection method as described above. The computer readable medium has no additional requirements on the configuration and structure of the existing condensing units and thus has universal applicability.

According to another aspect of the present invention, there is provided a controller for pre-protecting a condensing unit including a digital compressor having a capacity modulation function with a switching element capable of performing a load/unload switching of the digital compressor by performing a switching action, the digital compressor being set with an upper loading time percentage limit value and/or a lower loading time percentage limit value, the controller comprising: a data storage unit comprising a computer readable medium as described hereinbefore; a data acquisition unit that monitors and acquires data regarding the operating parameters and transmits the data to a data storage unit; a data processing unit reading the data in the data storage unit and executing a program in a computer readable medium, and then outputting the processing result to the digital compressor to adjust a maximum allowable load time percentage of the digital compressor.

According to a further aspect of the present invention, there is also provided a condensing unit, wherein the condensing unit comprises a controller as described hereinbefore.

According to the pre-protection method provided by the invention, the accidental stop of the compressor is reduced, the refrigerating capacity of the condensing unit can be better maintained, and compared with the prior art, the temperature of stored articles is more stable; the adaptability of the condensing unit is improved, and the condensing unit can work in a severe environment; in addition, the invention only needs to change the software, and has no investment cost of hardware, thereby saving the cost and being easy to realize.

Drawings

Features and advantages of one or more embodiments of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

fig. 1 is a schematic diagram of a condensing unit.

Fig. 2 is a control flow diagram of a pre-protection method according to an exemplary embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The scope of the invention is not limited to the specifically described embodiments.

Fig. 1 shows a condensing unit 100 comprising a refrigeration circuit for providing refrigeration to a storage item and a control device for providing thermostatic control to the refrigeration circuit. The refrigeration circuit mainly includes a compressor 110 (the compressor is a compressor capable of automatically adjusting output capacity, and here, a digital scroll compressor is taken as an example), a condenser 120 including a condensing fan 121, an expansion valve (e.g., an electronic expansion valve or a thermal expansion valve) 130, an evaporator 140, and a subcooler 160, which are connected in sequence by a pipeline. The compressor 110 also includes a solenoid valve 170 (as one embodiment of a switching element herein) that controls the loading or unloading of the compressor by a switching action (on or off). The control device may include a controller 150 and a driver for controlling the operation of the compressor 110, and the controller 150 may be divided into a hardware portion and a software portion including a control program, and is mainly used for providing output (control) signals (as shown by a single-dot chain line in fig. 1) for the compressor 110, the condensing fan 121, the expansion valve 130, and the like according to the monitoring information, so as to regulate and control the operating states of these devices.

The digital scroll compressor generally controls loading and unloading of the compressor through a solenoid valve (e.g., a PWM valve), that is, the capacity modulation of the digital compressor is realized by loading and unloading the digital compressor through opening and closing of the PWM solenoid valve. In particular, the solenoid valve is closed, i.e. the loading process, and the solenoid valve is open, i.e. the unloading process. In one implementation, when the electromagnetic valve is closed, the pressure in the back pressure cavity at the upper part of the fixed scroll is kept at a medium-high pressure, so that the pressure at the lower part of the fixed scroll is basically the same as that at the upper part of the fixed scroll, the fixed scroll and the movable scroll are attracted by gravity at the moment, the compressor is loaded, the compressor transmits the whole capacity, namely the output of the compressor is 100%, when the electromagnetic valve is opened, the back pressure cavity of the fixed scroll of the compressor is communicated with the air suction port, the pressure at the upper part of the fixed scroll is lower than that at the lower part of the fixed scroll, so that the fixed scroll is jacked up to be separated from the movable scroll, the compressor is unloaded, at the moment, the compressor does not compress the working fluid any more, and the output value of the compressor is 0. The compressor is alternately in a loaded state and an unloaded state. The digital scroll compressor thus achieves adjustability of the compressor output capacity by controlling the time ratio of loading/unloading. Specifically, the solenoid open time plus the closed time is an operating cycle in which the solenoid is closed for the entire cycle when at the maximum load time percentage, and the solenoid closed time and the solenoid open time are each half for the entire cycle when at the 50% load time percentage. Accordingly, in the condensing unit 100, the output power of the condensing unit 100 can be visually reflected by the loading time percentage of the compressor 110, and the larger the loading time percentage of the compressor 110 is, the larger the output capacity of the condensing unit 100 is, and vice versa. Under ideal operating conditions of the condensing unit, the compressor 110 can automatically adjust the output percentage according to the actual required cooling capacity to match the output to the required cooling capacity, thereby better maintaining the temperature of the articles in a constant ideal low temperature environment.

The controller may determine whether to adjust the output capacity of the compressor based on, for example, a relationship between the suction pressure of the compressor and a set value of the suction pressure stored in advance. As an example, if the actual suction pressure is above the set point, the controller will start the compressor and increase the output capacity of the compressor by increasing the loading time percentage of the compressor (solenoid valve in closed state) until the compressor is in the maximum loaded operating state. Conversely, if the actual suction pressure is below the set point, the controller may decrease the output percentage of the digital compressor and if the suction pressure is further decreased, the controller may stop the operation of the compressor.

However, as mentioned above, in some cases, the condensing unit cannot operate completely according to the relationship between the suction pressure and the set value, and particularly under the influence of a harsh environment, a safety switch in the compressor is triggered, so that the compressor is stopped accidentally. In particular, the applicant has noticed that, thanks to the presence of the high-pressure protection switch, in some adverse environmental conditions, such as an adverse ventilation environment, an extreme high ambient temperature or a dirty condenser, the condensation pressure increases to a limit value in a short time, triggering the opening of the high-pressure protection switch, causing an alarm shutdown, which not only affects the cold-retention effect of the stored goods, food, but also adversely affects the safety and the service life of the condensation unit.

To overcome an unexpected high pressure alarm shutdown due to adverse environmental conditions, the controller 150 of the present invention is configured to automatically adapt the output capacity of the compressor 110, which may be represented by a percentage of maximum allowable load time, for example, based on the relationship between the compressor operating parameters and corresponding predetermined values. Percentage of load time of solenoid valve in the prior artWhen the suction pressure is above the target value, the percentage of time the solenoid valve is loaded is increased to increase the output capacity and can reach a maximum of one hundred percent, calculated only from the relationship between the measured suction pressure and the target value. Here, the "percentage of loading time" is not completely equivalent to the "percentage of maximum allowable loading time". The percentage of the maximum allowable loading time refers to the percentage of the maximum allowable loading time of the compressor in a working period of the compressor in the working period. It will determine the maximum percentage of loading time that can be reached in the actual operation of the compressor, when this "maximum percentage of allowable loading time" is reached, the percentage of loading time cannot continue to increase even if the suction pressure is still above the target value. Typically, a range of maximum allowable percent load time OCA is also provided in the compressor, i.e., including a percent load time upper limit value OC_maxAnd a lower load time percentage limit value OC_minThe maximum allowable percentage of loading time OCA used during the operation of the compressor is not lower than the lower limit value of percentage of loading time OC_minNor greater than the upper limit value OC for percentage of loading time_maxThereby, it is possible to ensure safe and stable operation of the compressor while achieving a desired refrigeration effect.

The compressor operating parameter to be relied upon may be any operating parameter that can trigger the switching action of the switching element due to the fluctuation of the value to cause the unexpected unloading or stopping of the compressor, or any operating parameter associated with the triggering of the action of the switching element, thereby enabling the controller 150 to adjust the output capacity of the condensing unit 100 not only depending on the suction pressure, but also taking into account the value conditions of other operating parameters, in such a way as to adjust the output capacity of the condensing unit 100, so that the fluctuation of the value of the operating parameter is slowed down or even smoothed, thereby prolonging the time to reach the value causing the stopping, thereby being able to reduce the number of times of the unexpected stopping of the compressor 110 due to the bad fluctuation of the value of the operating parameter, and thus providing a measure of "pre-protection" for the condensing unit. By means of this pre-protection measure, it is possible on the one hand to ensure that the condensing unit maintains a sufficient and appropriate output capacity, and on the other hand to avoid various adverse effects of an accidental shutdown of the compressor in environmentally unfavorable conditions.

The controller 150 includes at least a data acquisition unit 152, a data storage unit 154, and a data processing unit 156. The data collection unit 152 is used for monitoring and collecting parameter values in real time (as exemplarily shown by a dotted line in fig. 1, parameters such as an operating parameter of the compressor 110 and a pressure and a temperature of the condenser 120 may be collected), and transmitting the collected data to the data storage unit 154 for storage, wherein the data collection unit 152 may include a monitoring device, for example, an element, such as a pressure sensor, a temperature sensor, and/or a current sensor, disposed at different positions of the condensing unit 100 for monitoring and measuring an operating condition or an operating parameter of each part, wherein the operating parameter may include, but is not limited to, a compressor rotation speed, a suction pressure, a suction saturation temperature, an evaporator temperature, an evaporation pressure, a condensation temperature, an exhaust temperature, a compressor operating current, and the like. The data storage unit 154 includes a computer-readable medium storing a control program, data, and the like; the data processing unit 156 processes the relevant data by executing the control program read from the memory unit 154 and transmits the processing results as output signals to the relevant actuators to perform the desired operation (including, but not limited to, adjusting the maximum allowable percentage load time of the compressor).

The term "computer-readable medium" as used herein refers to any medium that can store computer data. Computer-readable media include, but are not limited to, memory, Random Access Memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (FFPROM), flash memory, compact disc read-only, floppy disks, magnetic tape, other magnetic media, optical media, or any other device or medium capable of storing computer data.

Fig. 2 shows a flow chart of a pre-protection method for a condensation unit according to an exemplary embodiment of the present invention. Wherein, P₁、P₂……P_nRespectively indicating n operating parameters of the compressorThe controller 150, specifically the data storage unit 154, stores in advance a predetermined value P for each operating parameter_pxAnd a nominal threshold value P_txWhen the value P of one or more operating parameters_xReach the corresponding rated threshold value P_txAt this time, the switching element in the compressor will perform the switching action and unload or stop the compressor. And a predetermined value P_pxIs generally less than nominal threshold value P_txSo as to be able to extend the operating parameter up to the nominal threshold value P by adjusting the percentage of loading time of the compressor before shutdown_txThereby extending the time that the compressor is operated to reduce the frequency of false shutdowns. And in an embodiment according to the invention, the predetermined values of each operating parameter further comprise at least a first predetermined value P_px1And a second predetermined value P_px2Wherein the first predetermined value P_px1Greater than a second predetermined value P_px2The range of values between the two may be referred to as the "hysteresis interval", in general, when the value of the operating parameter falls within this hysteresis interval, no relevant adjustment is performed on the maximum allowable percentage of loading time of the compressor. In addition, neither the maximum allowable percent load time OCA before nor after adjustment can be greater than the percent load time upper limit value OC_maxNor less than the lower limit value OC for percentage of loading time_min。

As shown in fig. 2, the method comprises the steps of: a parameter acquisition step S100 of monitoring and collecting the real-time values P of the n operating parameters of the compressor 110₁、P₂……P_n(ii) a A decision step S102 of determining the value P of each operating parameter_xCorresponding first predetermined value P_px1Respectively comparing the values to determine whether the values of the predetermined number of working parameters are greater than or equal to the first predetermined value P_px1(ii) a If the result of the determination regarding one or more operating parameters is "yes" in the determination step S102, execution proceeds to step S104 to determine the first difference d₁Reducing the current maximum allowable load time percentage OCA; on the contrary, if the determination result is "no", the next determination step S106 is entered, in which the current maximum allowable load time percentage OCA is compared with the load timeUpper limit value of time percentage OC_maxComparing each value of the operating parameter with a corresponding second predetermined value P_px2Respectively comparing the current maximum allowable load time percentage OCA with the load time percentage upper limit value OC_maxAnd the values of a predetermined number of operating parameters are less than or equal to a second predetermined value P_px2(ii) a If the determination result obtained in the determination step is "yes", the process proceeds to another step S108 for executing a second difference d₂Increasing the maximum allowable load time percentage OCA; and if the judgment results are no, maintaining the current maximum allowable loading time percentage OCA unchanged.

Preferably, the above control routine is executed every predetermined time, for example, every 10 seconds, 20 seconds, or even 1 minute. This can be selected in combination with the actual operating conditions of the compressor and the environmental conditions, etc.

Here, it is to be noted that "n" is merely an example, where n is an arbitrary integer of 1 or more. Wherein, it may be set that the adjustment of the maximum allowable load time percentage OCA is performed when the determination result of a predetermined number of the n operating parameters satisfies the condition. Here, the "predetermined number" may be one or plural. It will be appreciated, however, that performing the adjustment of the maximum allowable load time percentage OCA only when the determination of one operating parameter satisfies the condition means that the response to a change in the operating condition of the compressor is most rapid.

As an exemplary embodiment, the pre-protection method according to the present invention determines that the maximum allowable load time percentage OCA of the compressor 110 needs to be increased or decreased by analyzing the operation parameters directly or indirectly related to the condensing pressure based on the aforementioned problem of unexpected shutdown caused by the increase of the condensing pressure, and calculates the maximum allowable load time percentage OCA to be adjusted by a difference value or a calculation formula preset in a program when it is determined that the maximum allowable load time percentage OCA of the compressor 110 needs to be increased or decreased. The operating parameter may be, for example, the condensation pressure itself, alternatively or additionally, or a parameter closely related to the condensation pressure, such as the condensation temperature, the compressor operating current, etc.

Illustratively, in the obtaining step S100, a value of one of a condensing pressure, a condensing temperature, and a compressor operation current is monitored and collected, and the condensing pressure is taken as an example here. In the determination step S102, the monitored value of the condensing pressure is compared with the first predetermined pressure value, when the value of the condensing pressure is determined to be greater than or equal to the first predetermined pressure value, the determination result is yes, and the process proceeds to step S104, where the first difference d is used₁The OCA is reduced. Wherein the first difference d₁May be a preset fixed value, such as 5%, which may also be calculated by the following equation:

d₁＝(P_px1-P_x)×r₁

wherein, P_xIs the value of an operating parameter to be monitored, here the value of the condensation pressure; p_px1A first predetermined value for said one operating parameter, here a first predetermined pressure value; r is₁The property of the adjustable coefficient is the conversion ratio between the working parameter and the loading time percentage. r is₁The size of (c) determines the amount of reduction of the maximum allowable load time percentage OCA, which can be selected by the user according to actual needs.

If the result of the determination in the previous determination step S102 is negative, the process proceeds to the next determination step S106, in which the current maximum allowable load time percentage OCA and the load time percentage upper limit value OC are compared_maxComparing the current maximum allowable load time percentage OCA with the upper load time percentage limit value OC when the current maximum allowable load time percentage OCA is judged to be smaller than the lower load time percentage upper limit value OC_maxAnd when the value of the condensing pressure is less than or equal to the second predetermined value, the judgment result is no, and the next step S108 is executed to obtain the second difference d₂The OCA is increased. Similarly, the second difference d₂It may also be a preset fixed value, such as 5%, or it may be calculated by the following equation:

d₂＝(P_px2-P_x)×r₂

wherein, P_xIs the value of an operating parameter, here the value of the condensation pressure; p_px2A second predetermined value for said one operating parameter, here a second predetermined pressure value; r is₂The property of the adjustable coefficient is the conversion ratio between the working parameter and the loading time percentage. r is₂The size of the load control unit determines the increase amount of the maximum allowable load time percentage OCA, and a user can select the increase amount according to actual requirements.

According to the method of the embodiment, when the compressor is operated at the reduced maximum allowable loading time percentage, the rising speed of the condensing pressure can be retarded on the premise of realizing the ideal cooling capacity, so that the shutdown of the compressor caused by the rising of the condensing pressure caused by the adverse environment can be reduced, and therefore, on one hand, the frequent fluctuation of the cooling temperature of the articles can be prevented, on the other hand, the damage to the machine can be reduced, and the service life of the machine can be prolonged.

As mentioned above, the above working parameters are only examples, and those skilled in the art can conceive of other parameters (especially parameters capable of causing unexpected shutdown due to numerical fluctuation) that reflect the working state of the condensing unit.

According to the method provided by the invention, when the values of some working parameters are obviously increased due to external factors under the condition of refrigeration demand, the output power of the compressor can be timely reduced by reducing the maximum allowable loading time percentage of the compressor, so that the increasing speed of the working parameters is reduced. Through this kind of regulation, on the one hand can guarantee the effective operation of condensing unit, maintain the constancy of temperature of article, on the other hand can also reduce the unexpected shut down number of times of machine, reduces the machine trouble or the life-span reduction that probably arouses because of frequent start/stop of compressor. The condenser unit has stronger adaptability and can adapt to severe working environment.

In addition, the working parameters required to be monitored by the method, such as the condensing pressure, the condensing temperature, the running current of the compressor and the like, belong to conventional monitoring parameters, and an additional monitoring device is not required to be added on the basis of the existing condensing unit, so that the control method provided by the invention is easy to realize and saves cost.

Furthermore, the adjustment of the output percentage can be achieved in other ways than by taking the maximum allowable percentage loading time as the adjustment target, for example by adjusting the rotational speed of the compressor.

Further, it will be understood by those skilled in the art that the manner in which the first and second differences are obtained is not necessarily limited to that exemplified herein, but may be otherwise employed.

Although specific embodiments of the invention have been described in detail herein, it is to be understood that the invention is not limited to the specific embodiments described and illustrated in detail herein, and that other modifications and variations may be effected by one skilled in the art without departing from the spirit and scope of the invention. All such variations and modifications are intended to be within the scope of the present invention. Moreover, all the elements or structures described herein may be replaced by other technically equivalent elements or structures.