Temperature control method and control panel of variable frequency heat pump of industrial oil cooler

Abstract

The invention provides a temperature control method for a variable frequency heat pump of an industrial oil cooler and a control panel. The method comprises the steps that when the set temperature is smaller than or equal to the difference between the environment temperature and the first preset temperature, the variable frequency heat pump is in a no-load or on-load state, auxiliary electric heating is stopped, and a compressor is started for refrigeration; when the set temperature is larger than or equal to the difference between the environment temperature and the second preset temperature and smaller than or equal to the sum of the environment temperature and the third preset temperature, auxiliary electric heating and compressor refrigeration are started at the same time when the variable-frequency heat pump is in a no-load state, and compressor refrigeration is started and auxiliary electric heating is stopped when the variable-frequency heat pump is in a loaded state; when the set temperature is larger than or equal to the sum of the environment temperature and the fourth preset temperature, auxiliary electric heating is started and compressor refrigeration is stopped when the variable-frequency heat pump is in a no-load state, and auxiliary electric heating is stopped and compressor refrigeration is started when the variable-frequency heat pump is in a loaded state; constant-temperature control is achieved by controlling electric heating and the compressor in stages, and the accuracy and stability of constant-temperature control are improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of heat pump control, and in particular to a temperature control method and a control board for a variable frequency heat pump of an industrial oil cooler. Background Art

[0002] Industrial oil coolers are designed to cool industrial machine tools by controlling the temperature of the circulating oil. When the machine is not in operation, it is considered unloaded. When it is running, it generates heat, acting as if it is under load. Constant temperature control is achieved through a variable-frequency heat pump combined with electric heating, with the heat pump providing cooling and the electric heating providing heating. To maintain the operating temperature of the industrial oil cooler, temperature control accuracy must be maintained within ±0.2°C of the set temperature, placing high demands on the precision and stability of the constant temperature control. Summary of the Invention

[0003] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0004] The purpose of this application is to solve one of the technical problems existing in the related art to at least a certain extent. The embodiment of this application provides a temperature control method and a control board for a variable frequency heat pump of an industrial oil cooler, which improves the accuracy and stability of constant temperature control.

[0005] An embodiment of the first aspect of the present application provides a temperature control method for a variable frequency heat pump of an industrial oil cooler, comprising:

[0006] Get the set temperature and ambient temperature of the variable frequency heat pump;

[0007] When the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the variable frequency heat pump is in no-load or loaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on;

[0008] When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the variable frequency heat pump is in an unloaded state, the auxiliary electric heating and the compressor cooling are turned on; when the variable frequency heat pump is in a loaded state, the compressor cooling is turned on and the auxiliary electric heating is turned off;

[0009] When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the variable frequency heat pump is in an unloaded state, the auxiliary electric heating is turned on and the compressor cooling is turned off; and when the variable frequency heat pump is in a loaded state, the auxiliary electric heating is turned off and the compressor cooling is turned on;

[0010] The second preset temperature is lower than the first preset temperature, and the third preset temperature is lower than the fourth preset temperature.

[0011] According to certain embodiments of the first aspect of the present application, when the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the frequency of the compressor is controlled in the following manner:

[0012] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased;

[0013] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

[0014] According to certain embodiments of the first aspect of the present application, when the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the frequency of the compressor is controlled in the following manner:

[0015] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval;

[0016] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval;

[0017] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

[0018] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the frequency of the compressor is controlled in the following manner:

[0019] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased;

[0020] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

[0021] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the frequency of the compressor is controlled in the following manner:

[0022] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval;

[0023] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval;

[0024] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

[0025] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, it is determined whether the compressor is unloaded or loaded in the following manner:

[0026] When the time during which the frequency of the compressor is less than or equal to 35 Hz is greater than or equal to a first time threshold, it is determined that the compressor is in an unloaded state;

[0027] When the time during which the frequency of the compressor is greater than or equal to 40 Hz is greater than or equal to a first time threshold, it is determined that the compressor is under load.

[0028] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the frequency of the compressor is controlled in the following manner:

[0029] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased;

[0030] When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

[0031] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the frequency of the compressor is controlled in the following manner:

[0032] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval;

[0033] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval;

[0034] When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

[0035] According to certain embodiments of the first aspect of the present application, when the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, it is determined whether the compressor is unloaded or loaded in the following manner:

[0036] When the oil temperature rise rate is greater than or equal to 0.09 degrees Celsius per second and the time is greater than or equal to the second time threshold, it is determined that the compressor is under load;

[0037] When the oil temperature rise rate is less than or equal to 0.06 degrees Celsius per second and the time is greater than or equal to the second time threshold, it is determined that the compressor is in no-load state.

[0038] An embodiment of the second aspect of the present application is a control board, which applies the temperature control method of the variable frequency heat pump of the industrial oil cooler as described in the embodiment of the first aspect of the present application.

[0039] The above scheme has at least the following beneficial effects: when the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the variable frequency heat pump is in no-load or loaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on; when the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the variable frequency heat pump is in no-load state, the auxiliary electric heating and compressor cooling are turned on, and the variable frequency heat pump is in loaded state, the compressor cooling is turned on and the auxiliary electric heating is turned off; when the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the variable frequency heat pump is in no-load state, the auxiliary electric heating is turned on and the compressor cooling is turned off, and the variable frequency heat pump is in loaded state, the auxiliary electric heating is turned off and the compressor cooling is turned on; constant temperature control is achieved by controlling the electric heating and compressor in stages, thereby improving the accuracy and stability of constant temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0041] Figure 1 This is a step diagram of the temperature control method of the variable frequency heat pump of the industrial oil cooler;

[0042] Figure 2 This is a schematic diagram of the control panel;

[0043] Figure 3 This is the circuit diagram of the MCU of the control board;

[0044] Figure 4 This is the circuit diagram of the communication circuit of the control board;

[0045] Figure 5 This is the circuit diagram of the drive side of the control board;

[0046] Figure 6 This is the circuit diagram of the main control side of the control board;

[0047] Figure 7 This is the circuit diagram of the host computer communication circuit of the control board;

[0048] Figure 8 This is a circuit diagram of the control board's setup circuit. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0050] It should be noted that although the device schematics illustrate functional module divisions and the flowcharts illustrate logical sequences, in certain circumstances, the steps shown or described may be performed in a sequence that differs from the module divisions in the device or the sequence in the flowcharts. The terms "first," "second," and the like in the specification, claims, or accompanying drawings are used to distinguish similar items and are not necessarily used to describe a specific sequence or precedence.

[0051] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0052] An embodiment of the present application provides a temperature control method for a variable frequency heat pump of an industrial oil cooler.

[0053] Reference Figure 1 The temperature control method of the variable frequency heat pump of the industrial oil cooler includes the following steps:

[0054] Step S100, obtaining the set temperature and ambient temperature of the variable frequency heat pump;

[0055] Step S200: When the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the variable frequency heat pump is in no-load or loaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on;

[0056] Step S300: When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the auxiliary electric heating and the compressor cooling are turned on when the variable frequency heat pump is in an unloaded state; and when the variable frequency heat pump is in a loaded state, the compressor cooling is turned on and the auxiliary electric heating is turned off;

[0057] Step S400: When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the auxiliary electric heating is turned on and the compressor cooling is turned off when the variable frequency heat pump is in an unloaded state; and when the variable frequency heat pump is in a loaded state, the auxiliary electric heating is turned off and the compressor cooling is turned on;

[0058] The second preset temperature is lower than the first preset temperature, and the third preset temperature is lower than the fourth preset temperature.

[0059] In this embodiment, constant temperature control is achieved by controlling the electric heating and the compressor in stages, thereby improving the accuracy and stability of the constant temperature control.

[0060] The set temperature of the variable frequency heat pump is input by the user through an input device (such as a key, etc.) and stored in the memory of the industrial oil cooler. When the set temperature of the variable frequency heat pump needs to be obtained, the set temperature of the variable frequency heat pump is read from the memory.

[0061] The ambient temperature is obtained through the ambient temperature sensor.

[0062] Through three stages, the variable frequency heat pump of the industrial oil cooler is controlled according to the set temperature of the variable frequency heat pump and the ambient temperature to achieve constant temperature control.

[0063] In the first stage, when the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the variable frequency heat pump is in no-load or loaded state, the auxiliary electric heating is turned off, and the compressor is turned on for cooling.

[0064] In this embodiment, the first preset temperature is 10 degrees Celsius. Of course, in other embodiments, the first preset temperature can be set to other values ​​according to actual needs. Specifically, when the set temperature is ≤ the ambient temperature -10°C, the variable frequency heat pump is in an unloaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on; when the set temperature is ≤ the ambient temperature -10°C, the variable frequency heat pump is in a loaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on.

[0065] When the set temperature is ≤ -10°C (-10°C) from the ambient temperature, the ambient temperature is much higher than the set temperature. Therefore, even when the variable frequency heat pump is unloaded, there is no need to activate auxiliary electric heating; simply turning on the compressor for cooling can maintain a constant temperature. When the machine tool is running, which is equivalent to having a heat source, and the variable frequency heat pump is loaded, simply turning on the compressor for cooling and slightly increasing the compressor frequency can maintain a constant temperature.

[0066] When the set temperature is ≤ -10°C from the ambient temperature, the compressor is always on, regardless of whether the variable frequency heat pump is unloaded or loaded. The compressor frequency is controlled as follows: When the difference between the oil temperature and the set temperature is greater than 1°C, and the oil cooling rate is less than the preset target cooling rate, the compressor frequency is increased. When the difference between the oil temperature and the set temperature is greater than 1°C, and the oil cooling rate is greater than or equal to the preset target cooling rate, the compressor frequency is decreased. When the difference between the oil temperature and the set temperature is between 0.2°C and 1°C, the compressor frequency is increased at preset intervals as the oil temperature rises. When the oil temperature decreases, the compressor frequency is decreased at preset intervals. When the oil temperature remains constant, the compressor frequency is increased if the oil temperature is greater than the set temperature, and decreased if the oil temperature is less than the set temperature.

[0067] In this embodiment, the target cooling rate is set to -0.02°C / second, and the preset time interval is 3 seconds. Of course, in other embodiments, the target cooling rate and the preset time interval can be set to other values ​​according to actual production requirements.

[0068] Specifically, when the oil temperature differs from the set temperature by more than 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 2°C, the target cooling rate is -0.02°C / second. If the cooling rate is less than -0.02°C / second, the compressor frequency is increased to increase cooling capacity. If the cooling rate is greater than or equal to -0.02°C / second, the compressor frequency is decreased to reduce cooling capacity.

[0069] When the oil temperature differs from the set temperature by 1°C to 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 1°C, the target cooling rate is -0.01°C / second. If the cooling rate is less than -0.01°C / second, the compressor frequency is increased to increase the cooling capacity. If the cooling rate is greater than or equal to -0.01°C / second, the compressor frequency is decreased to reduce the cooling capacity.

[0070] When the oil temperature differs from the set temperature by 0.2°C to 1°C, the compressor frequency is adjusted every 3 seconds based on the temperature change. If the oil temperature rises every 3 seconds, the compressor frequency increases by 0.1Hz; if the oil temperature drops every 3 seconds, the compressor frequency decreases by 0.1Hz. If the oil temperature remains constant for more than 10 seconds, the compressor frequency is adjusted based on the difference between the oil temperature and the set temperature. For example, if the oil temperature is above the set temperature, the compressor frequency is increased by 0.1Hz; if the oil temperature is below the set temperature, the compressor frequency is decreased by 0.1Hz.

[0071] In the second stage, when the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the variable frequency heat pump is in no-load state, and the auxiliary electric heating and compressor cooling are turned on; when the variable frequency heat pump is in load state, the compressor cooling is turned on and the auxiliary electric heating is turned off.

[0072] In this embodiment, the second preset temperature is 9 degrees Celsius. Of course, in other embodiments, the second preset temperature can be set to other values ​​based on actual needs, but the condition must be met: the second preset temperature is less than the first preset temperature. The third preset temperature is 9 degrees Celsius. Of course, in other embodiments, the third preset temperature can be set to other values ​​based on actual needs, but the condition must be met: the third preset temperature is less than the fourth preset temperature. Specifically, when the ambient temperature is -9°C ≤ the set temperature ≤ the ambient temperature +9°C, the variable frequency heat pump is unloaded, and the auxiliary electric heating and compressor cooling are activated. When the variable frequency heat pump is loaded, the compressor cooling is activated and the auxiliary electric heating is deactivated.

[0073] When the ambient temperature is -9°C ≤ set temperature ≤ ambient temperature +9°C, the ambient temperature is similar to the set temperature. Even if the variable frequency heat pump is unloaded, both the auxiliary electric heating and the compressor cooling must be turned on simultaneously to stabilize the temperature. In this case, the auxiliary electric heating is always on, and the compressor stabilizes the temperature by adjusting its frequency. However, when the machine tool is running, which is equivalent to having a heat source, the variable frequency heat pump is loaded, and only the compressor cooling can be turned on; the auxiliary electric heating is not required.

[0074] If it is unloaded, the compressor frequency will be relatively low. If it is loaded, the compressor will run at a relatively high frequency. Whether the compressor is unloaded or loaded is determined in the following manner: when the frequency of the compressor is less than or equal to 35 Hz and the time is greater than or equal to the first time threshold, the compressor is determined to be unloaded; when the frequency of the compressor is greater than or equal to 40 Hz and the time is greater than or equal to the first time threshold, the compressor is determined to be loaded. In this embodiment, the first time threshold is 30 seconds. Of course, in other embodiments, the first time threshold can be set to other values ​​according to actual production needs. Specifically, when the compressor frequency is ≤35Hz for 30 consecutive seconds, it is determined to be unloaded; when the compressor frequency is ≥40Hz for 30 consecutive seconds, it is determined to be loaded.

[0075] When the ambient temperature is -9°C ≤ set temperature ≤ ambient temperature +9°C, the compressor is always on, regardless of whether the variable frequency heat pump is unloaded or loaded. The compressor frequency is controlled as follows: When the difference between the oil temperature and the set temperature is greater than 1°C, and the oil cooling rate is less than the preset target cooling rate, the compressor frequency is increased. When the difference between the oil temperature and the set temperature is greater than 1°C, and the oil cooling rate is greater than or equal to the preset target cooling rate, the compressor frequency is decreased. When the difference between the oil temperature and the set temperature is between 0.2°C and 1°C, the compressor frequency is increased at preset intervals as the oil temperature rises. When the oil temperature falls, the compressor frequency is decreased at preset intervals. If the oil temperature remains constant, the compressor frequency is increased if the oil temperature is greater than the set temperature, and decreased if the oil temperature is less than the set temperature.

[0076] In this embodiment, the target cooling rate is set to -0.02°C / second, and the preset time interval is 3 seconds. Of course, in other embodiments, the target cooling rate and the preset time interval can be set to other values ​​according to actual production requirements.

[0077] Specifically, when the oil temperature differs from the set temperature by more than 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 2°C, the target cooling rate is -0.02°C / second. If the cooling rate is less than -0.02°C / second, the compressor frequency is increased to increase cooling capacity. If the cooling rate is greater than or equal to -0.02°C / second, the compressor frequency is decreased to reduce cooling capacity.

[0078] When the oil temperature differs from the set temperature by 1°C to 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 1°C, the target cooling rate is -0.01°C / second. If the cooling rate is less than -0.01°C / second, the compressor frequency is increased to increase the cooling capacity. If the cooling rate is greater than or equal to -0.01°C / second, the compressor frequency is decreased to reduce the cooling capacity.

[0079] When the oil temperature differs from the set temperature by 0.2°C to 1°C, the compressor frequency is adjusted every 3 seconds based on the temperature change. If the oil temperature rises every 3 seconds, the compressor frequency increases by 0.1Hz; if the oil temperature drops every 3 seconds, the compressor frequency decreases by 0.1Hz. If the oil temperature remains constant for more than 10 seconds, the compressor frequency is adjusted based on the difference between the oil temperature and the set temperature. For example, if the oil temperature is above the set temperature, the compressor frequency is increased by 0.1Hz; if the oil temperature is below the set temperature, the compressor frequency is decreased by 0.1Hz.

[0080] In the third stage, when the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, if the variable frequency heat pump is in no-load state, the auxiliary electric heating is turned on and the compressor cooling is turned off; if the variable frequency heat pump is in load state, the auxiliary electric heating is turned off and the compressor cooling is turned on.

[0081] In this embodiment, the fourth preset temperature is 10 degrees Celsius. Of course, in other embodiments, the fourth preset temperature can be set to other values ​​based on actual needs, but the following conditions must be met: the second preset temperature is less than the first preset temperature. The third preset temperature is less than the fourth preset temperature. Specifically, when the set temperature is ≥ the ambient temperature + 10°C, the auxiliary electric heating is turned on and the compressor cooling is turned off when the variable frequency heat pump is unloaded. When the variable frequency heat pump is loaded, the auxiliary electric heating is turned off and the compressor cooling is turned on.

[0082] When the set temperature is ≥ ambient temperature + 10°C (higher than ambient temperature), and the variable frequency heat pump is unloaded, only the auxiliary electric heating is turned on to raise the oil temperature without turning on the compressor. However, when the machine tool is running, which is equivalent to having a heat source, the variable frequency heat pump is loaded. In this case, only the compressor is turned on to keep the temperature down, without turning on the auxiliary electric heating.

[0083] When the set temperature is ≥ the ambient temperature + 10°C, the compressor is judged to be unloaded or loaded in the following manner: when the oil temperature rise rate is greater than or equal to 0.09 degrees Celsius per second for a period greater than or equal to a second time threshold, the compressor is judged to be loaded; when the oil temperature rise rate is less than or equal to 0.06 degrees Celsius per second for a period greater than or equal to the second time threshold, the compressor is judged to be unloaded. In this embodiment, the second time threshold is 30 seconds. Of course, in other embodiments, the second time threshold can be set to other values ​​based on actual production requirements.

[0084] When the compressor is unloaded, only the auxiliary electric heater is turned on, so the temperature rise rate is only about 0.05°C / second. However, if the compressor is loaded, the temperature rise rate will reach about 0.1°C / second or more. Therefore, when the compressor is unloaded, the temperature rise rate can be used to determine whether the compressor is unloaded or loaded. Specifically, if the temperature rise rate is ≥0.09°C / second for 30 consecutive seconds, it is judged to be loaded, and if the temperature rise rate is ≤0.06°C / second for 30 consecutive seconds, it is judged to be unloaded.

[0085] When the set temperature is ≥ ambient temperature + 10°C, and it is determined to be loaded, it is equivalent to having a heat source. Only turning on the compressor for cooling can stabilize the temperature, without turning on auxiliary electric heating. The compressor frequency is controlled as follows: When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1°C, and the oil temperature cooling rate is less than the preset target cooling rate, the compressor frequency is increased; when the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1°C, and the oil temperature cooling rate is greater than or equal to the preset target cooling rate, the compressor frequency is reduced; when the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2°C and 1°C, the compressor frequency is increased at preset time intervals as the oil temperature rises; the compressor frequency is reduced at preset time intervals as the oil temperature decreases; if the oil temperature remains unchanged, the compressor frequency is increased if the oil temperature is greater than the set temperature, and decreased if the oil temperature is less than the set temperature.

[0086] In this embodiment, the target cooling rate is set to -0.02°C / second, and the preset time interval is 3 seconds. Of course, in other embodiments, the target cooling rate and the preset time interval can be set to other values ​​according to actual production requirements.

[0087] Specifically, when the oil temperature differs from the set temperature by more than 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 2°C, the target cooling rate is -0.02°C / second. If the cooling rate is less than -0.02°C / second, the compressor frequency is increased to increase cooling capacity. If the cooling rate is greater than or equal to -0.02°C / second, the compressor frequency is decreased to reduce cooling capacity.

[0088] When the oil temperature differs from the set temperature by 1°C to 2°C, the compressor cooling is controlled based on the cooling rate. For example, when the oil temperature is ≥ the set temperature + 1°C, the target cooling rate is -0.01°C / second. If the cooling rate is less than -0.01°C / second, the compressor frequency is increased to increase the cooling capacity. If the cooling rate is greater than or equal to -0.01°C / second, the compressor frequency is decreased to reduce the cooling capacity.

[0089] When the oil temperature differs from the set temperature by 0.2°C to 1°C, the compressor frequency is adjusted every 3 seconds based on the temperature change. If the oil temperature rises every 3 seconds, the compressor frequency increases by 0.1Hz; if the oil temperature drops every 3 seconds, the compressor frequency decreases by 0.1Hz. If the oil temperature remains constant for more than 10 seconds, the compressor frequency is adjusted based on the difference between the oil temperature and the set temperature. For example, if the oil temperature is above the set temperature, the compressor frequency is increased by 0.1Hz; if the oil temperature is below the set temperature, the compressor frequency is decreased by 0.1Hz.

[0090] Another embodiment of the present application provides a control panel.

[0091] The control panel applies the temperature control method of the variable frequency heat pump of the industrial oil cooler as above.

[0092] Reference Figure 2 The control board is provided with an MCU, and multiple interfaces are configured for the MCU, including an interface for the ground wire, an interface for the live wire, an interface for the neutral wire, an interface for the bypass electronic expansion valve, an interface for the water pump, an interface for the crankshaft electric heating, an interface for the electric heating, an interface for the remote control switch, an interface for the high-pressure switch, an interface for the phase sequence switch, an interface for the water flow switch, an interface for the exhaust temperature sensor, an interface for the return air temperature sensor, an interface for the ambient temperature sensor, an interface for the outlet water temperature sensor, an interface for the inlet water temperature sensor, an interface for the wiring control, an interface for the fault output, and a reserved interface.

[0093] Circuit reference of the MCU of the control board Figure 3 ; Circuit reference for the communication circuit of the control board Figure 4 ; The circuit reference of the drive side of the control board Figure 5 ; Circuit reference for the main control side of the control board Figure 6 ; Circuit reference for the host computer communication circuit of the control board Figure 7 ; Circuit reference for setting circuit of control board Figure 8 .

[0094] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present application. These equivalent modifications or substitutions.

Claims

1. A temperature control method for a variable frequency heat pump of an industrial oil cooler, characterized in that: include: Get the set temperature and ambient temperature of the variable frequency heat pump; When the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the variable frequency heat pump is in no-load or loaded state, the auxiliary electric heating is turned off, and the compressor cooling is turned on; When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the variable frequency heat pump is in an unloaded state, the auxiliary electric heating and the compressor cooling are turned on; when the variable frequency heat pump is in a loaded state, the compressor cooling is turned on and the auxiliary electric heating is turned off; When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the variable frequency heat pump is in an unloaded state, the auxiliary electric heating is turned on and the compressor cooling is turned off; and when the variable frequency heat pump is in a loaded state, the auxiliary electric heating is turned off and the compressor cooling is turned on; The second preset temperature is lower than the first preset temperature, and the third preset temperature is lower than the fourth preset temperature.

2. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased; When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

3. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is less than or equal to the difference between the ambient temperature and the first preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

4. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased; When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

5. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

6. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the difference between the ambient temperature and the second preset temperature, and the set temperature is less than or equal to the sum of the ambient temperature and the third preset temperature, it is determined whether the compressor is unloaded or loaded in the following manner: When the time during which the frequency of the compressor is less than or equal to 35 Hz is greater than or equal to a first time threshold, it is determined that the compressor is in an unloaded state; When the time during which the frequency of the compressor is greater than or equal to 40 Hz is greater than or equal to a first time threshold, it is determined that the compressor is under load.

7. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, and the oil temperature cooling rate is lower than the preset target cooling rate, the frequency of the compressor is increased; When the difference between the oil temperature of the industrial oil cooler and the set temperature is greater than 1 degree Celsius, the oil temperature cooling rate is greater than or equal to the preset target cooling rate, and the frequency of the compressor is reduced.

8. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, the frequency of the compressor is controlled in the following manner: When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature rises and the frequency of the compressor is increased at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature decreases and the frequency of the compressor is reduced at a preset time interval; When the difference between the oil temperature of the industrial oil cooler and the set temperature is between 0.2 degrees Celsius and 1 degree Celsius, the oil temperature remains unchanged. When the oil temperature is greater than the set temperature, the frequency of the compressor is increased, and when the oil temperature is less than the set temperature, the frequency of the compressor is reduced.

9. The temperature control method of the variable frequency heat pump of the industrial oil cooler according to claim 1, characterized in that: When the set temperature is greater than or equal to the sum of the ambient temperature and the fourth preset temperature, whether the compressor is unloaded or loaded is determined in the following manner: When the oil temperature rise rate is greater than or equal to 0.09 degrees Celsius per second and the time is greater than or equal to the second time threshold, it is determined that the compressor is under load; When the oil temperature rise rate is less than or equal to 0.06 degrees Celsius per second and the time is greater than or equal to the second time threshold, it is determined that the compressor is in no-load state.

10. A control panel, characterized in that: A temperature control method for a variable frequency heat pump of an industrial oil cooler using the method described in any one of claims 1 to 9.

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