A method and device for controlling the step size of the rotational speed of a variable frequency compressor, and a refrigeration system

Abstract

The embodiment of the application discloses a variable frequency compressor speed step control method, device and refrigerating system. The variable frequency compressor is applied to an environmental test equipment. The speed step control method comprises the following steps: obtaining a current condensing pressure of an inner tank of the environmental test equipment and a condensing pressure at a preset time point before a current time point; determining a change rate of the current condensing pressure and the condensing pressure at the preset time point according to the current condensing pressure and the condensing pressure at the preset time point; and controlling a speed step of the variable frequency compressor according to the change rate, a preset condensing pressure deviation and a preset step correction value. The variable frequency compressor speed step control method, device and refrigerating system provided by the embodiment of the application can save energy consumption and improve energy-saving effect.

Description

Technical Field

[0001] The embodiments of the present invention relate to compressor control technology, and more particularly to a method, device and refrigeration system for controlling the speed step size of a variable frequency compressor. Background Technology

[0002] For refrigeration systems using variable frequency compressors, energy consumption is affected by the compressor's rotational speed. The compressor's speed can be adjusted based on a speed step size. To reduce energy consumption, reliable control of this speed step size is necessary. However, current speed step size control methods for variable frequency compressors often suffer from low reliability when adjusting the step size, such as reducing it. This can lead to higher energy consumption and negatively impact energy-saving performance. Summary of the Invention

[0003] This invention provides a method, apparatus, and refrigeration system for controlling the speed step size of a variable frequency compressor, in order to save energy and improve energy-saving effect.

[0004] In a first aspect, embodiments of the present invention provide a speed step control method for a variable frequency compressor, wherein the variable frequency compressor is applied to environmental testing equipment, and the speed step control method includes:

[0005] Obtain the current condensing pressure inside the environmental testing equipment chamber and the condensing pressure at a preset time prior to the current time;

[0006] Based on the current condensing pressure and the condensing pressure at a preset time, determine the rate of change of the current condensing pressure and the condensing pressure at the preset time.

[0007] The speed step size of the variable frequency compressor is controlled based on the rate of change, the preset condensing pressure deviation, and the preset step size correction value.

[0008] Optionally, based on the current condensing pressure and the condensing pressure at a preset time, the rate of change of the current condensing pressure and the condensing pressure at a preset time is determined, including:

[0009] Determine the difference between the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time.

[0010] The ratio of the difference to the time difference between the current time and the preset time is used as the rate of change.

[0011] Optionally, the preset step size correction values ​​include a preset first step size correction value, a preset second step size correction value, and a preset third step size correction value;

[0012] Based on the rate of change, preset condensing pressure deviation, and preset step size correction value, the speed step size of the variable frequency compressor is controlled, including:

[0013] When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is less than the preset third step length correction value, the preset adjustment value of the speed step length is adjusted to the product of the preset first step length correction value and the first value; the first value is the absolute value obtained by taking the product of the rate of change and the preset second step length correction value.

[0014] When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is less than the preset third step length correction value, the preset adjustment value of the speed step length is adjusted to the product of the preset first step length correction value and the second value; the second value is the product of the absolute value of the rate of change and the preset second step length correction value.

[0015] Adjust the speed step size of the variable frequency compressor according to the preset adjustment value of the speed step size.

[0016] Optionally, the speed step size of the variable frequency compressor can be adjusted according to a preset adjustment value, including:

[0017] If the preset adjustment value of the speed step size is less than or equal to the preset minimum speed change step size, then the preset adjustment value will be adjusted to the preset minimum speed change step size.

[0018] When the adjusted preset adjustment value is greater than the preset maximum speed change step size, the preset maximum speed change step size is used as the speed step size of the variable frequency compressor.

[0019] When the adjusted preset adjustment value is less than or equal to the maximum preset speed change step size, the adjusted preset adjustment value is used as the speed step size of the variable frequency compressor.

[0020] Optionally, the speed step size of the variable frequency compressor can be adjusted according to a preset adjustment value, including:

[0021] If the preset adjustment value is greater than the preset minimum speed change step size and less than or equal to the preset maximum speed change step size, then the preset adjustment value at this time will be used as the speed step size of the variable frequency compressor.

[0022] If the preset adjustment value of the speed step size is greater than the preset maximum value of the speed change step size, then the preset maximum value of the speed change step size will be used as the speed step size of the variable frequency compressor.

[0023] Optionally, the speed step size of the variable frequency compressor is controlled based on the rate of change, the preset condensing pressure deviation, and the preset step size correction value, including:

[0024] When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is greater than or equal to zero, the preset adjustment value of the speed step size is adjusted to the preset minimum speed change step size.

[0025] Adjust the speed step size of the variable frequency compressor according to the preset adjustment value of the speed step size.

[0026] Optionally, the speed step size of the variable frequency compressor can be adjusted according to a preset adjustment value, including:

[0027] If the preset adjustment value of the speed step size is less than or equal to the maximum preset speed change step size, then the preset adjustment value at this time will be used as the speed step size of the variable frequency compressor.

[0028] If the preset adjustment value of the speed step size is greater than the preset maximum value of the speed change step size, then the preset maximum value of the speed change step size will be used as the speed step size of the variable frequency compressor.

[0029] Secondly, embodiments of the present invention also provide a speed step control device for a variable frequency compressor, wherein the variable frequency compressor is applied to environmental testing equipment, and the speed step control device includes:

[0030] The data acquisition module is used to acquire the current condensing pressure of the inner chamber of the environmental testing equipment and the condensing pressure at a preset time before the current time;

[0031] The rate determination module is used to determine the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time.

[0032] The step size control module is used to control the speed step size of the variable frequency compressor based on the rate of change, the preset condensing pressure deviation, and the preset step size correction value.

[0033] Thirdly, embodiments of the present invention also provide a refrigeration system, including a controller, a variable frequency compressor, a condenser, and an evaporator. The controller is electrically connected to the variable frequency compressor. The condenser is connected to the evaporator and the variable frequency compressor via a pipeline. The evaporator is connected to the variable frequency compressor via a pipeline. The speed step control device as described in claim 8 is integrated into the controller.

[0034] Optionally, the refrigeration system may also include an electronic expansion valve, which is located in the passage connecting the evaporator and the inverter compressor.

[0035] The present invention provides a method, apparatus, and refrigeration system for controlling the speed step size of a variable frequency compressor. The variable frequency compressor is applied to an environmental testing device. The method acquires the current condensing pressure of the inner chamber of the environmental testing device and the condensing pressure at a preset time prior to the current time. Based on the current condensing pressure and the condensing pressure at the preset time, the rate of change of the current condensing pressure and the condensing pressure at the preset time are determined. Based on the rate of change, a preset condensing pressure deviation, and a preset step size correction value, the speed step size of the variable frequency compressor is controlled. The method, apparatus, and refrigeration system provided by the present invention control the speed step size of the variable frequency compressor based on the determined rate of change, the preset condensing pressure deviation, and the preset step size correction value, thereby improving the reliability of the speed step size control of the variable frequency compressor, saving energy, and improving energy-saving effects. Attached Figure Description

[0036] Figure 1 This is a flowchart of a speed step control method for a variable frequency compressor provided in Embodiment 1 of the present invention;

[0037] Figure 2 This is a structural block diagram of a refrigeration system provided in Embodiment 1 of the present invention;

[0038] Figure 3 This is a flowchart of a speed step control method for a variable frequency compressor provided in Embodiment 2 of the present invention;

[0039] Figure 4 This is a flowchart of another speed step control method for a variable frequency compressor provided in Embodiment 2 of the present invention;

[0040] Figure 5 This is a structural block diagram of a speed step control device for a variable frequency compressor provided in Embodiment 3 of the present invention. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0042] Example 1

[0043] Figure 1 This is a flowchart of a speed step size control method for a variable frequency compressor provided in Embodiment 1 of the present invention. This embodiment is applicable to situations where the speed step size of the variable frequency compressor is adjusted, such as by reducing it. The variable frequency compressor is used in environmental testing equipment. This method can be executed by a speed step size control device for the variable frequency compressor. This device can be implemented by software and / or hardware. The device can be integrated into the controller of the refrigeration system. The method specifically includes the following steps:

[0044] Step 110: Obtain the current condensing pressure of the inner chamber of the environmental test equipment and the condensing pressure at a preset time before the current time.

[0045] The current condensing pressure and the condensing pressure at a preset time before the current time can be collected in real time by a pressure sensor installed inside the environmental test equipment. The speed step control device is electrically connected to the pressure sensor to obtain the current condensing pressure and the condensing pressure at a preset time before the current time inside the environmental test equipment.

[0046] Step 120: Determine the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time.

[0047] Specifically, the rate of change of the current condensing pressure P_cond_(n) and the condensing pressure TPV(n-1) at the preset time is [P_cond_(n)-P_cond_(n-1)] / [t(n)-t(n-1)], where t(n) is the current time and t(n-1) is the preset time.

[0048] Step 130: Control the speed step of the variable frequency compressor according to the rate of change, the preset condensing pressure deviation, and the preset step correction value.

[0049] For example, Figure 2 This is a schematic diagram of a refrigeration system provided in Embodiment 1 of the present invention. (Reference) Figure 2 The refrigeration system includes a controller 10, a variable frequency compressor 20, a condenser, and an evaporator 30. The controller 10 is electrically connected to the variable frequency compressor 20. The condenser is connected to the evaporator 30 and the variable frequency compressor 20 via piping. The evaporator 30 is connected to the variable frequency compressor 20 via piping. The speed step control device, as described in any embodiment of the present invention, is integrated into the controller 10. The refrigeration system also includes an electronic expansion valve, which is located in the passage connecting the evaporator and the variable frequency compressor.

[0050] Specifically, the controller 10 can control the magnitude of the speed step reduction of the variable frequency compressor 20. For example, when the rate of change is greater than or equal to the preset condensing pressure deviation, the preset adjustment value of the speed step is adjusted to the minimum value of the preset speed change step. If the adjusted preset adjustment value is less than or equal to the maximum value of the preset speed change step, then the preset adjustment value at this time is used as the speed step of the variable frequency compressor.

[0051] It should be noted that each preset value in this embodiment can be set according to the actual speed step size control requirements, and is not limited here.

[0052] The variable frequency compressor speed step size control method provided in this embodiment obtains the current condensing pressure of the inner chamber of the environmental test equipment and the condensing pressure at a preset time before the current time; determines the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time; and controls the speed step size of the variable frequency compressor based on the rate of change, the preset condensing pressure deviation, and the preset step size correction value. This variable frequency compressor speed step size control method, based on the determined rate of change, the preset condensing pressure deviation, and the preset step size correction value, can improve the reliability of speed step size control of the variable frequency compressor, thereby saving energy and improving energy-saving effect.

[0053] Example 2

[0054] Figure 3 This is a flowchart of a speed step size control method for a variable frequency compressor provided in Embodiment 2 of the present invention. This embodiment is applicable to situations where the speed step size of the variable frequency compressor is adjusted, such as by reducing it. The variable frequency compressor is used in environmental testing equipment. This method can be executed by a speed step size control device for the variable frequency compressor. This device can be implemented by software and / or hardware. The device can be integrated into the controller of the refrigeration system. The method specifically includes the following steps:

[0055] Step 210: Obtain the current condensing pressure of the inner chamber of the environmental test equipment and the condensing pressure at a preset time before the current time.

[0056] Step 220: Determine the difference between the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time.

[0057] Step 230: Use the ratio of the difference to the time difference between the current time and the preset time as the rate of change.

[0058] Step 240: When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is less than the preset third step length correction value, then the preset adjustment value of the speed step length is adjusted to the product of the preset first step length correction value and the first value.

[0059] The preset step size correction values ​​include a preset first step size correction value, a preset second step size correction value, and a preset third step size correction value. The first value is the absolute value obtained by multiplying the rate of change by the preset second step size correction value.

[0060] Step 250: When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is less than the preset third step length correction value, then the preset adjustment value of the speed step length is adjusted to the product of the preset first step length correction value and the second value.

[0061] The second value is the product of the absolute value of the rate of change and the preset second step size correction value.

[0062] Step 260: If the preset adjustment value of the speed step is less than or equal to the preset minimum speed change step, then adjust the preset adjustment value to the preset minimum speed change step.

[0063] Step 270: When the adjusted preset adjustment value is greater than the preset maximum speed change step size, the preset maximum speed change step size is used as the speed step size of the variable frequency compressor.

[0064] Step 280: When the adjusted preset adjustment value is less than or equal to the maximum preset speed change step size, the adjusted preset adjustment value is used as the speed step size of the variable frequency compressor.

[0065] Step 290: If the preset adjustment value is greater than the preset minimum speed change step size and less than or equal to the preset maximum speed change step size, then the preset adjustment value at this time shall be used as the speed step size of the variable frequency compressor.

[0066] Step 291: If the preset adjustment value of the speed step is greater than the preset maximum value of the speed change step, then the preset maximum value of the speed change step is used as the speed step of the variable frequency compressor.

[0067] Step 292: When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is greater than or equal to zero, adjust the preset adjustment value of the speed step size to the preset minimum speed change step size.

[0068] Step 293: If the preset adjustment value of the speed step is less than or equal to the maximum preset speed change step value, then the preset adjustment value at this time shall be used as the speed step of the variable frequency compressor.

[0069] Step 294: If the preset adjustment value of the speed step is greater than the preset maximum value of the speed change step, then the preset maximum value of the speed change step is used as the speed step of the variable frequency compressor.

[0070] Figure 4 This is a flowchart of another speed step control method for a variable frequency compressor provided in Embodiment 2 of the present invention. (See reference) Figure 4 The method includes the following steps:

[0071] Step 1: Obtain the current condensing pressure P_cond_(n) of the inner chamber of the environmental test equipment and the condensing pressure TPV(n-1) at the preset time before the current time.

[0072] Step 2: Determine the rate of change of P_cond_(n) and TPV(n-1) as dP_cond_t_diff as [P_cond_(n)-P_cond_(n-1)] / [t(n)-t(n-1)], and that P_cond_(n) is less than P_diff_1.

[0073] Where P_diff_1 is the preset condensation pressure deviation.

[0074] Step 3: Determine whether [P_cond_(n)-P_cond_(n-1)] / [t(n)-t(n-1)] is less than 0; if yes, proceed to step 4; if no, proceed to step 12.

[0075] Step 4: Determine if dP_cond_t_diff is less than P_rpm_step_change_corr_3; if yes, proceed to step 5; if no, proceed to step 6.

[0076] P_rpm_step_change_corr_3 is the preset third step size correction value.

[0077] Step 5: Adjust f(a,b,c,...)_3 to P_rpm_step_change_corr_1*ROUND((ABS(P_rpm_step_change_corr_2*dP_cond_t_diff)),1), and then execute Step 7.

[0078] Where f(a,b,c,...)_3 is the preset adjustment value of the speed step size, P_rpm_step_change_corr_1 is the preset first step size correction value, P_rpm_step_change_corr_2 is the preset second step size correction value, ROUND is the rounding operation, and ABS is the absolute value operation.

[0079] Step 6: Adjust f(a,b,c,...)_3 to P_rpm_step_change_corr_1*ROUND((ABS(P_rpm_step_change_corr_2*dP_cond_t_diff)),1), and then execute Step 7.

[0080] Where P_rpm_step_change_corr_1 is the preset first step length correction value, P_rpm_step_change_corr_2 is the preset second step length correction value, ROUND is the rounding operation, and ABS is the absolute value operation.

[0081] Step 7: Determine whether f(a,b,c,...)_3 is less than or equal to Δrpm_step_decrease_min; if yes, proceed to step 8; if no, proceed to step 9.

[0082] Wherein, △rpm_step_decrease_min is the preset minimum step size for speed change.

[0083] Step 8: Adjust f(a,b,c,...)_3 to △rpm_step_decrease_min.

[0084] Step 9: Determine whether f(a,b,c,...)_3 is less than or equal to Δrpm_step_decrease_max; if yes, proceed to step 10; if no, proceed to step 11.

[0085] Wherein, △rpm_step_decrease_max is the maximum preset speed change step size.

[0086] Step 10: Use f(a,b,c,...)_3 as the speed step size of the variable frequency compressor.

[0087] Step 11: Use △rpm_step_decrease_max as the speed step size of the variable frequency compressor.

[0088] Step 12: Adjust f(a,b,c,...)_3 to △rpm_step_decrease_min, and return to Step 9.

[0089] It should be noted that each preset value in this embodiment can be set according to the actual speed step size control requirements, and is not limited here.

[0090] The variable frequency compressor speed step size control method provided in this embodiment controls the speed step size of the variable frequency compressor based on the determined rate of change, the preset condensing pressure deviation, and the preset step size correction value. This can improve the reliability of the speed step size control of the variable frequency compressor, thereby saving energy and improving energy-saving effect.

[0091] Example 3

[0092] Figure 5This is a structural block diagram of a speed step control device for a variable frequency compressor provided in Embodiment 3 of the present invention. The variable frequency compressor is applied to environmental testing equipment. The speed step control device includes: a data acquisition module 310, a rate determination module 320, and a step control module 330. The data acquisition module 310 is used to acquire the current condensing pressure of the inner chamber of the environmental testing equipment and the condensing pressure at a preset time prior to the current time. The rate determination module 320 is used to determine the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time. The step control module 330 is used to control the speed step of the variable frequency compressor based on the rate of change, a preset condensing pressure deviation, and a preset step correction value.

[0093] Based on the above implementation, the rate determination module 320 includes a difference determination unit and a rate determination unit. The difference determination unit is used to determine the difference between the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time. The rate determination unit is used to use the ratio of the difference to the time difference between the current time and the preset time as the rate of change.

[0094] Optionally, the preset step size correction value includes a preset first step size correction value, a preset second step size correction value, and a preset third step size correction value; the step size control module 330 includes a first adjustment unit, a second adjustment unit, and a third adjustment unit. The first adjustment unit is used to adjust the preset adjustment value of the speed step size to the product of the preset first step size correction value and a first value when the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, and the rate of change is less than the preset third step size correction value; the second adjustment unit is used to adjust the preset adjustment value of the speed step size to the product of the preset first step size correction value and a second value when the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, and the rate of change is less than the preset third step size correction value; the second value is the product of the absolute value of the rate of change and the preset second step size correction value; the third adjustment unit is used to adjust the speed step size of the variable frequency compressor according to the preset adjustment value of the speed step size.

[0095] Optionally, the third adjustment unit includes: a first adjustment subunit, a second adjustment subunit, and a third adjustment subunit. The first adjustment subunit is used to adjust the preset adjustment value to the preset minimum speed change step if the preset adjustment value of the speed step is less than or equal to the preset minimum speed change step. The second adjustment subunit is used to use the preset maximum speed change step as the speed step of the variable frequency compressor when the adjusted preset adjustment value is greater than the preset maximum speed change step. The third adjustment subunit is used to use the adjusted preset adjustment value as the speed step of the variable frequency compressor when the adjusted preset adjustment value is less than or equal to the preset maximum speed change step.

[0096] Optionally, the third adjustment unit includes a fourth adjustment subunit and a fifth adjustment subunit. The fourth adjustment subunit is used to take the preset adjustment value as the speed step of the variable frequency compressor if the preset adjustment value is greater than the preset minimum speed change step size and less than or equal to the preset maximum speed change step size. The fifth adjustment subunit is used to take the preset maximum speed change step size as the speed step of the variable frequency compressor if the preset adjustment value of the speed step size is greater than the preset maximum speed change step size.

[0097] Optionally, the step size control module 330 includes a fourth adjustment unit and a fifth adjustment unit. The fourth adjustment unit is used to adjust the preset adjustment value of the speed step size to the preset minimum speed change step size when the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is greater than or equal to zero. The fifth adjustment unit is used to adjust the speed step size of the variable frequency compressor according to the preset adjustment value of the speed step size.

[0098] Optionally, the fifth adjustment unit includes a sixth adjustment subunit and a seventh adjustment subunit. The sixth adjustment subunit is used to take the preset adjustment value of the speed step size as the speed step size of the variable frequency compressor if the preset adjustment value of the speed step size is less than or equal to the preset maximum speed change step size. The seventh adjustment subunit is used to take the preset maximum speed change step size as the speed step size of the variable frequency compressor if the preset adjustment value of the speed step size is greater than the preset maximum speed change step size.

[0099] The speed step control device for the variable frequency compressor provided in this embodiment belongs to the same inventive concept as the speed step control method for the variable frequency compressor provided in any embodiment of the present invention, and has corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the speed step control method for the variable frequency compressor provided in any embodiment of the present invention.

[0100] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for controlling the speed step size of a variable frequency compressor, characterized in that, The variable frequency compressor is used in environmental testing equipment, and the speed step control method includes: Obtain the current condensation pressure of the inner chamber of the environmental testing equipment and the condensation pressure at a preset time before the current time; Based on the current condensing pressure and the condensing pressure at the preset time, determine the rate of change of the current condensing pressure and the condensing pressure at the preset time; The speed step size of the variable frequency compressor is controlled according to the rate of change, the preset condensing pressure deviation, and the preset step size correction value. The preset step size correction value includes a preset first step size correction value, a preset second step size correction value, and a preset third step size correction value; The step of controlling the speed step of the variable frequency compressor based on the rate of change, the preset condensing pressure deviation, and the preset step correction value includes: When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is less than the preset third step length correction value, then the preset adjustment value of the rotation speed step length is adjusted to the product of the preset first step length correction value and the first value; the first value is the value obtained by taking the absolute value of the product of the rate of change and the preset second step length correction value. When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is less than zero, if the rate of change is greater than or equal to the preset third step length correction value, then the preset adjustment value of the rotation speed step is adjusted to the product of the preset first step length correction value and the second value; the second value is the product of the absolute value of the rate of change and the preset second step length correction value. The speed step size of the variable frequency compressor is adjusted according to the preset adjustment value of the speed step size.

2. The speed step size control method according to claim 1, characterized in that, The step of determining the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time includes: The difference between the current condensing pressure and the condensing pressure at the preset time is determined based on the current condensing pressure and the condensing pressure at the preset time. The rate of change is defined as the ratio of the difference to the time difference between the current time and the preset time.

3. The speed step size control method according to claim 1, characterized in that, The step of adjusting the speed step of the variable frequency compressor according to the preset adjustment value of the speed step includes: If the preset adjustment value of the speed step size is less than or equal to the preset minimum speed change step size, then the preset adjustment value is adjusted to the preset minimum speed change step size. When the adjusted preset adjustment value is greater than the preset maximum speed change step size, the preset maximum speed change step size is used as the speed step size of the variable frequency compressor. When the adjusted preset adjustment value is less than or equal to the maximum preset speed change step size, the adjusted preset adjustment value is used as the speed step size of the variable frequency compressor.

4. The speed step size control method according to claim 1, characterized in that, The step of adjusting the speed step of the variable frequency compressor according to the preset adjustment value of the speed step includes: If the preset adjustment value is greater than the minimum preset speed change step size and less than or equal to the maximum preset speed change step size, then the preset adjustment value at this time is taken as the speed step size of the variable frequency compressor. If the preset adjustment value of the speed step is greater than the preset maximum value of the speed change step, then the preset maximum value of the speed change step is used as the speed step of the variable frequency compressor.

5. The speed step size control method according to claim 1, characterized in that, The step of controlling the speed step of the variable frequency compressor based on the rate of change, the preset condensing pressure deviation, and the preset step correction value includes: When the current condensing pressure is less than the preset condensing pressure deviation and the rate of change is greater than or equal to zero, the preset adjustment value of the speed step size is adjusted to the preset minimum speed change step size. The speed step size of the variable frequency compressor is adjusted according to the preset adjustment value of the speed step size.

6. The speed step size control method according to claim 5, characterized in that, The step of adjusting the speed step of the variable frequency compressor according to the preset adjustment value of the speed step includes: If the preset adjustment value of the speed step is less than or equal to the maximum preset speed change step value, then the preset adjustment value at this time is taken as the speed step of the variable frequency compressor. If the preset adjustment value of the speed step is greater than the preset maximum value of the speed change step, then the preset maximum value of the speed change step is used as the speed step of the variable frequency compressor.

7. A speed step control device for a variable frequency compressor, used to execute the speed step control method for a variable frequency compressor as described in any one of claims 1-6, characterized in that, The variable frequency compressor is used in environmental testing equipment, and the speed step control device includes: The data acquisition module is used to acquire the current condensation pressure of the inner chamber of the environmental test equipment and the condensation pressure at a preset time before the current time; A rate determination module is used to determine the rate of change of the current condensing pressure and the condensing pressure at the preset time based on the current condensing pressure and the condensing pressure at the preset time. The step size control module is used to control the speed step size of the variable frequency compressor based on the change rate, the preset condensing pressure deviation, and the preset step size correction value.

8. A refrigeration system, characterized in that, The device includes a controller, a variable frequency compressor, a condenser, and an evaporator. The controller is electrically connected to the variable frequency compressor. The condenser is connected to the evaporator and the variable frequency compressor via a pipeline. The evaporator is connected to the variable frequency compressor via a pipeline. The speed step control device as described in claim 7 is integrated into the controller.

9. The refrigeration system according to claim 8, characterized in that, It also includes an electronic expansion valve, which is disposed in the passage connecting the evaporator and the variable frequency compressor.

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