A method, system and air conditioning unit for preventing periodic fluctuations in compressor frequency

Abstract

The application discloses a method, system and air conditioning device for preventing compressor frequency periodic fluctuation, the method comprising the steps of: entering the exhaust temperature regulation limited frequency function when the compressor frequency starts to periodically fluctuate; obtaining the lowest exhaust temperature, the highest exhaust temperature, the frequency change speed and the highest operating frequency in the last exhaust frequency reduction protection period of the compressor; reducing the highest operating frequency of the compressor according to the highest operating frequency in the last exhaust frequency reduction protection period; improving the recovery frequency increase exhaust temperature value of the compressor according to the lowest exhaust temperature and the highest exhaust temperature; and adjusting the frequency change speed of the compressor according to the frequency change speed in the last exhaust frequency reduction protection period. The application solves the compressor frequency periodic fluctuation problem by adjusting the highest operating frequency, the recovery frequency increase exhaust temperature value and the frequency change speed of the compressor, thereby improving the reliability of the air conditioning unit and the use comfort of the user.

Description

Technical Field

[0001] This invention belongs to the field of air conditioning technology, and specifically relates to a method, system and air conditioning device for preventing periodic fluctuations in compressor frequency. Background Technology

[0002] When an air conditioner is running, under harsh conditions, if the set outlet temperature is not reached, the compressor will need to increase its frequency to achieve better cooling and heating. However, due to the harsh conditions, the increased compressor frequency increases the air conditioner's load and raises the exhaust temperature, affecting the reliability of the air conditioner.

[0003] Currently, in situations like the aforementioned, some frequency reduction protection conditions are generally set. When the air conditioning unit load increases to a certain level, the frequency increase is limited, or even reduced, to ensure stable operation of the air conditioning unit at the expense of performance. This operation is called "exhaust frequency reduction protection." In actual operation, due to different system load states under different usage scenarios, the exhaust frequency reduction protection conditions set by the air conditioning unit at the factory may not be applicable to all situations. In this case, the air conditioning compressor frequency may experience periodic fluctuations, affecting the reliability of the air conditioning unit and user comfort. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method, system and air conditioning device to prevent periodic fluctuations in compressor frequency, thereby solving the problem of periodic fluctuations in compressor frequency and improving the reliability of air conditioning units and user comfort.

[0005] This invention provides the following technical solution:

[0006] In a first aspect, a method for preventing periodic fluctuations in compressor frequency is provided, comprising the following steps:

[0007] When the compressor frequency begins to fluctuate periodically, the exhaust temperature regulation frequency limiting function is activated.

[0008] Obtain the lowest discharge temperature, highest discharge temperature, frequency change rate, and highest operating frequency during the last discharge frequency reduction protection cycle of the compressor;

[0009] Reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle;

[0010] The compressor's recovery frequency boosting exhaust temperature value is increased based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle.

[0011] Adjust the compressor's frequency change rate based on the frequency change rate during the last exhaust frequency reduction protection cycle.

[0012] Furthermore, the steps to determine that the compressor frequency begins to fluctuate periodically include: during the continuous operation of the compressor, if the exhaust frequency reduction protection is triggered more than twice within period T, and the operating frequency of the compressor is the same each time the exhaust frequency reduction protection is triggered, and the duration of each exhaust frequency reduction protection differs by less than 1 minute, then the compressor frequency is considered to have begun to fluctuate periodically.

[0013] Furthermore, the period T is 10–30 min.

[0014] Furthermore, the formula for calculating the maximum operating frequency of the reduced compressor is as follows:

[0015] P max (n+1)=P max (n)-E

[0016] In the formula, P max (n+1) represents the highest operating frequency of the compressor after the reduction, P max (n) is the highest operating frequency during the last discharge frequency reduction protection cycle of the compressor, and E is 1 to 3 Hz.

[0017] Furthermore, E is 2Hz.

[0018] Furthermore, the formula for calculating the restored frequency-increased exhaust temperature of the compressor is as follows:

[0019] T min (n+1)=T min (n)+0.2*(T max (n)-T min (n))

[0020] In the formula, T min (n+1) represents the improved compressor's restored frequency-increased exhaust temperature value, T min (n) and T max (n) represents the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle of the compressor, respectively.

[0021] Furthermore, the formula for calculating the rate of change of the adjusted compressor frequency is as follows:

[0022] V(n+1)=0.1*(T max (n)-T min (n))*V(n)

[0023] In the formula, V(n+1) is the rate of change of the compressor frequency after adjustment, V(n) is the rate of change of the compressor frequency during the last discharge frequency reduction protection cycle, and T min (n) and T max(n) represents the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle of the compressor, respectively.

[0024] Furthermore, if the compressor does not trigger the exhaust frequency reduction protection again within time T0, the exhaust temperature regulation frequency limiting function will exit; otherwise, the exhaust temperature regulation frequency limiting function will re-enter. T0 is preferably 1 to 2 hours.

[0025] Secondly, a system for preventing periodic fluctuations in compressor frequency is provided, comprising:

[0026] The judgment module is used to determine when the compressor frequency begins to fluctuate periodically, thus triggering the exhaust temperature regulation frequency limiting function;

[0027] The data acquisition module is used to acquire the lowest exhaust temperature, highest exhaust temperature, frequency change rate, and highest operating frequency during the last exhaust frequency reduction protection cycle of the compressor.

[0028] The maximum operating frequency adjustment module is used to reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle.

[0029] The frequency-increasing exhaust temperature regulation module is used to increase the compressor's frequency-increasing exhaust temperature value based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle.

[0030] The frequency change rate adjustment module is used to adjust the compressor's frequency change rate according to the frequency change rate during the last exhaust frequency reduction protection cycle.

[0031] Thirdly, an air conditioning device is provided, including a compressor and a controller, the controller being used to perform the method described in the first aspect for preventing periodic fluctuations in the compressor frequency.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] When the compressor frequency begins to fluctuate periodically, this invention activates the exhaust temperature regulation and frequency limiting function. By adjusting the compressor's maximum operating frequency, restoring the frequency-increased exhaust temperature value, and adjusting the frequency change rate, the problem of periodic compressor frequency fluctuations is solved, thereby improving the reliability of the air conditioning unit and the user's comfort. Attached Figure Description

[0034] Figure 1 This is a flowchart of a method for preventing periodic fluctuations in compressor frequency in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a method for preventing periodic fluctuations in compressor frequency, including the following steps:

[0038] (1) During the continuous operation of the compressor, if the exhaust frequency reduction protection is triggered more than twice within a period T (generally 10 to 30 minutes), and the operating frequency of the compressor is the same each time the exhaust frequency reduction protection is triggered, and the duration of each exhaust frequency reduction protection is within 1 minute, then it is considered that the compressor frequency has started to fluctuate periodically and enters the exhaust temperature regulation frequency limiting function.

[0039] (2) Obtain the lowest exhaust temperature T during the last exhaust frequency reduction protection cycle of the compressor. min (n), Maximum exhaust temperature T max (n), frequency change rate V(n) and maximum operating frequency P max (n).

[0040] The change in the compressor's exhaust temperature is caused by the change in its operating frequency. Therefore, the point corresponding to the lowest exhaust temperature is the exhaust temperature point at which the compressor resumes its frequency increase operation, after which the compressor begins to increase its frequency.

[0041] (3) Reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle. The reduced compressor's maximum operating frequency P max The formula for calculating (n+1) is:

[0042] P max (n+1)=P max (n)-E

[0043] In the formula, E is 1 to 3 Hz, preferably 2 Hz.

[0044] When the compressor's operating frequency changes, the exhaust temperature will change accordingly. However, the change in exhaust temperature lags slightly behind the change in frequency. Therefore, the compressor frequency corresponding to the exhaust temperature value that triggers protection should theoretically be lower than the actual compressor frequency at this time (for example, if the set exhaust temperature protection value is 100℃, when the compressor's operating frequency is 95Hz, the actual stable operating exhaust temperature is 100℃, which has reached the high-pressure protection value. However, since the change in exhaust temperature lags behind the change in compressor frequency, during the frequency increase process, when the compressor frequency is 95Hz, the exhaust temperature may only be 92℃, which has not reached the protection value. The compressor will continue to increase the frequency. When the exhaust temperature reaches the protection value, the compressor frequency has actually exceeded the highest operating frequency). However, the specific corresponding frequency is unknown. Therefore, it is necessary to limit the highest frequency of the compressor one by one to find the critical point (that is, the compressor frequency that makes the system exhaust temperature just equal to or slightly lower than the protection value after stabilization).

[0045] (4) Increase the compressor's recovery frequency increase exhaust temperature value based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle. The increased compressor recovery frequency increase exhaust temperature value T min The formula for calculating (n+1) is:

[0046] T min (n+1)=T min (n)+0.2*(T max (n)-T min (n))

[0047] The purpose of increasing the compressor's recovery frequency exhaust temperature value is to reduce the range of exhaust temperature (frequency) fluctuations, bring it as close as possible to the stable exhaust temperature, shorten the adjustment time, and ensure that the exhaust temperature rise is related to the range of exhaust temperature changes within the cycle.

[0048] (5) Adjust the compressor's frequency change rate based on the frequency change rate during the last exhaust frequency reduction protection cycle. The formula for calculating the adjusted compressor's frequency change rate V(n+1) is:

[0049] V(n+1)=0.1*(T max (n)-T min (n))*V(n)

[0050] The rate of frequency change, which is the time interval between each frequency change, is controllable. The purpose of this action is to slow down the rate of frequency change of the compressor, ensuring that the unit's exhaust gas reaches a stable value at that frequency after each frequency change. Initially, the range of exhaust temperature variation is large, and the slowdown in the rate of frequency change is small. As the adjustment progresses, the range of exhaust temperature variation decreases, and the slowdown in the rate of frequency change increases. The rate of frequency change is correlated with the range of exhaust temperature variation.

[0051] (6) In order to avoid the exhaust temperature regulation frequency limiting function (steps (2) to (5)) from being too low due to improved operating conditions and affecting the cooling and heating effect, it is set that if the compressor does not trigger the exhaust frequency reduction protection again within time T0 (generally 1 to 2 hours), the exhaust temperature regulation frequency limiting function will be exited; otherwise, the exhaust temperature regulation frequency limiting function will be re-entered.

[0052] Example 2

[0053] This embodiment takes an air conditioning unit as an example and uses the method in Embodiment 1 to prevent continuous periodic fluctuations in the compressor frequency.

[0054] When a unit is started up and running, after a period of time, the compressor's operating frequency and exhaust temperature exhibit periodic changes. For two consecutive cycles, the compressor's operating frequency fluctuates from 85 Hz to a maximum of 95 Hz, and the exhaust temperature fluctuates from 100℃ to 90℃. At this point, the exhaust temperature regulation frequency limiting function is activated, adjusting the compressor's maximum operating frequency from 95 Hz to 93 Hz, restoring the frequency increase, and the exhaust temperature rises from 90℃ to 92℃, while the rate of frequency change remains constant.

[0055] Afterwards, the compressor frequency fluctuated from 87 Hz to a maximum of 93 Hz, and the exhaust temperature fluctuated from 92 ℃ to 100 ℃. That is, the compressor frequency started to fluctuate periodically again. Therefore, the exhaust temperature regulation frequency limiting function was activated again, and the compressor's maximum operating frequency was adjusted from 93 Hz to 90 Hz. The frequency was restored and the exhaust temperature value was increased from 92 ℃ to 93.6 ℃. The frequency change rate was slowed down to 0.8 times the original value.

[0056] This process is repeated (which may require multiple adjustments). When the compressor frequency is 90 Hz, the high-pressure temperature remains around 100°C, entering the stable discharge temperature range. The compressor maintains its current frequency, and the system operates stably. If the compressor does not trigger the discharge frequency reduction protection again within 2 hours, the discharge temperature regulation frequency limiting function is deactivated.

[0057] Example 3

[0058] This embodiment provides a system for preventing periodic fluctuations in compressor frequency, operating using the method for preventing periodic fluctuations in compressor frequency described in Embodiment 1, specifically including:

[0059] The judgment module is used to determine when the compressor frequency begins to fluctuate periodically, thus triggering the exhaust temperature regulation frequency limiting function;

[0060] The data acquisition module is used to acquire the lowest exhaust temperature, highest exhaust temperature, frequency change rate, and highest operating frequency during the last exhaust frequency reduction protection cycle of the compressor.

[0061] The maximum operating frequency adjustment module is used to reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle.

[0062] The frequency-increasing exhaust temperature regulation module is used to increase the compressor's frequency-increasing exhaust temperature value based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle.

[0063] The frequency change rate adjustment module is used to adjust the compressor's frequency change rate according to the frequency change rate during the last exhaust frequency reduction protection cycle.

[0064] Example 4

[0065] This embodiment provides an air conditioning device equipped with a compressor and a controller. The compressor is connected to the controller, and the controller is used to execute the method for preventing periodic fluctuations in compressor frequency as described in Embodiment 1.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preventing periodic fluctuations in compressor frequency, characterized in that, Includes the following steps: When the compressor frequency begins to fluctuate periodically, the exhaust temperature regulation frequency limiting function is activated. Obtain the lowest discharge temperature, highest discharge temperature, frequency change rate, and highest operating frequency during the last discharge frequency reduction protection cycle of the compressor; Reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle; The compressor's recovery frequency boosting exhaust temperature value is increased based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle. Adjust the compressor's frequency change rate according to the frequency change rate during the last exhaust frequency reduction protection cycle; The formula for calculating the restored frequency-increased exhaust temperature of the compressor is as follows: T min (n+1)=T min (n)+0.2*(T max (n)-T min (n)); In the formula, T min (n+1) represents the improved compressor's restored frequency-increased exhaust temperature value, T min (n) and T max (n) represents the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle of the compressor, respectively.

2. The method for preventing periodic fluctuations in compressor frequency according to claim 1, characterized in that, The steps to determine if the compressor frequency begins to fluctuate periodically include: during continuous operation of the compressor, if the discharge frequency reduction protection is triggered more than twice within period T, and the compressor operating frequency is the same each time the discharge frequency reduction protection is triggered, and the duration of each discharge frequency reduction protection differs by less than 1 minute, then the compressor frequency is considered to have begun to fluctuate periodically.

3. The method for preventing periodic fluctuations in compressor frequency according to claim 2, characterized in that, The period T is 10~30min.

4. The method for preventing periodic fluctuations in compressor frequency according to claim 1, characterized in that, The formula for calculating the maximum operating frequency of the reduced compressor is: P max (n+1)=P max (n)-E; In the formula, P max (n+1) represents the highest operating frequency of the compressor after the reduction, P max (n) represents the highest operating frequency during the last discharge frequency reduction protection cycle of the compressor, and E is 1~3Hz.

5. The method for preventing periodic fluctuations in compressor frequency according to claim 4, characterized in that, The value of E is 2Hz.

6. The method for preventing periodic fluctuations in compressor frequency according to claim 1, characterized in that, The formula for calculating the rate of change of the adjusted compressor frequency is: V(n+1)=0.1*(T max (n)-T min (n))* V(n); In the formula, V(n+1) is the rate of change of the compressor frequency after adjustment, V(n) is the rate of change of the compressor frequency during the last discharge frequency reduction protection cycle, and T min (n) and T max (n) represents the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle of the compressor, respectively.

7. The method for preventing periodic fluctuations in compressor frequency according to claim 1, characterized in that, If the compressor does not trigger the exhaust frequency reduction protection again within time T0, the exhaust temperature regulation frequency limiting function will be exited; otherwise, the exhaust temperature regulation frequency limiting function will be re-entered.

8. A system for preventing periodic fluctuations in compressor frequency, characterized in that, include: The judgment module is used to determine when the compressor frequency begins to fluctuate periodically, thus triggering the exhaust temperature regulation frequency limiting function; The data acquisition module is used to acquire the lowest exhaust temperature, highest exhaust temperature, frequency change rate, and highest operating frequency during the last exhaust frequency reduction protection cycle of the compressor. The maximum operating frequency adjustment module is used to reduce the compressor's maximum operating frequency based on the highest operating frequency during the last exhaust frequency reduction protection cycle. The frequency-increasing exhaust temperature regulation module is used to increase the compressor's frequency-increasing exhaust temperature value based on the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle. The frequency change rate adjustment module is used to adjust the compressor's frequency change rate according to the frequency change rate during the last exhaust frequency reduction protection cycle. The formula for calculating the restored frequency-increased exhaust temperature of the compressor is as follows: T min (n+1)=T min (n)+0.2*(T max (n)-T min (n)); In the formula, T min (n+1) represents the improved compressor's restored frequency-increased exhaust temperature value, T min (n) and T max (n) represents the lowest and highest exhaust temperatures during the last exhaust frequency reduction protection cycle of the compressor, respectively.

9. An air conditioning device, characterized in that, It includes a compressor and a controller, the controller being used to perform the method for preventing periodic fluctuations in compressor frequency as described in any one of claims 1 to 7.

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