A frequency converter temperature and humidity control system and control method

Abstract

The present invention discloses a frequency converter temperature and humidity control system and control method, including: a detection unit and a control unit, wherein the detection unit is used to collect the ambient temperature, ambient humidity and surface temperature of the capacitor in the frequency converter, and the control unit is electrically connected to the detection unit and the frequency converter respectively, and is used to process the ambient temperature, ambient humidity and surface temperature data and send a control signal to the frequency converter to stop or start according to the processing result. In the present invention, the controller can prevent the frequency converter from exploding due to excessive temperature of the capacitor in the intermediate circuit or excessive humidity in the frequency converter by real-time monitoring of the changes in the ambient temperature and humidity in the frequency converter and the surface temperature of the capacitor in the intermediate circuit. At the same time, these monitoring data can provide necessary and effective data references for the maintenance of the frequency converter, and finally realize the protection control of the frequency converter.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency converters, and in particular to a frequency converter temperature and humidity control system and a control method. Background Art

[0002] Frequency converter is a device that uses software control algorithms and hardware control systems to control the on and off of power semiconductor devices, thereby converting industrial frequency power into AC power of various frequencies to achieve variable speed operation of motors. It is a power converter in motion control systems. Currently, the most widely used and most widely used is the AC-DC-AC voltage type frequency converter, that is, there is a DC energy storage filter link in the middle, and generally a large-capacity electrolytic capacitor is used to achieve this function.

[0003] When the inverter is running, if the ambient temperature is greater than 40℃, the inverter will be derated by 5% for every 1℃ increase. In addition, when ripple current flows through the electrolytic capacitor for a long time, the electrode of the electrolytic capacitor will oxidize, resulting in an increase in internal resistance, which will cause an increase in leakage current, an increase in temperature rise, and an increase in heat generation, which will further cause a decrease in electrolyte and a decrease in capacity. On the one hand, the reduction in capacity will easily cause the electrolytic capacitor to resonate with the equivalent inductance (including load inductance) of the inverter circuit of the inverter, generating overvoltage and causing the inverter module and rectifier module of the inverter to be broken down; on the other hand, it will reduce the load capacity and power factor of the inverter. When the load is heavy, it will cause a sharp drop in the DC bus voltage, causing the inverter to alarm or even shut down.

[0004] If the inverter is placed in a high humidity environment for a long time, many tiny water droplets will condense on the circuit board. If the water droplets happen to be between the two electrodes of the electrolytic capacitor on the circuit board, it will inevitably cause the capacitance of the electrolytic capacitor to change or the insulation to decrease and break down. If the water droplets are on the DC bus circuit or the wiring terminals, a phase-to-phase short circuit or DC discharge explosion accident will occur during startup. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a frequency converter temperature and humidity control system and control method to achieve real-time monitoring of the ambient temperature and humidity in the frequency converter, the temperature of the capacitor, and protection control of the frequency converter.

[0006] According to the first aspect of the present invention, the inverter temperature and humidity control system includes: a detection unit and a control unit, wherein the detection unit is used to collect the ambient temperature, ambient humidity and surface temperature of the capacitor in the inverter, and the control unit is electrically connected to the detection unit and the inverter respectively, and is used to process the ambient temperature, ambient humidity and surface temperature data and send a control signal to the inverter to stop or start operation according to the processing result.

[0007] The inverter temperature and humidity control system according to the above embodiment of the present invention has at least the following beneficial effects: the controller can prevent the inverter from exploding due to excessive temperature of the capacitor in the intermediate circuit or excessive humidity in the inverter by real-time monitoring of changes in the ambient temperature and humidity in the inverter and the surface temperature of the capacitor in the intermediate circuit. At the same time, these monitoring data can provide necessary and effective data reference for the maintenance of the inverter.

[0008] According to some embodiments of the present invention, the detection unit includes: a K-type thermocouple temperature sensor, a thermocouple input module, and a temperature and humidity transmitter. The K-type thermocouple temperature sensor is arranged on the capacitor, the thermocouple input module is electrically connected to the control unit and the K-type thermocouple temperature sensor, respectively, and the temperature and humidity transmitter is arranged inside the inverter and is electrically connected to the control unit.

[0009] According to some embodiments of the present invention, the K-type thermocouple temperature sensor is RKC ST-50.

[0010] According to some embodiments of the present invention, the thermocouple input module and the temperature and humidity transmitter are both electrically connected to the control unit via a MODBUS bus.

[0011] According to some embodiments of the present invention, the thermocouple input module model is DAM-3037.

[0012] According to some embodiments of the present invention, the temperature and humidity transmitter model is TH11S-B.

[0013] According to some embodiments of the present invention, the control unit is a PLC control module, and the model of the PLC control module is S7-200 SMART.

[0014] According to some embodiments of the present invention, the inverter temperature and humidity control system also includes a human-computer interaction unit, which is electrically connected to the control unit and is used to display the ambient temperature, ambient humidity, surface temperature and capacitor temperature rise value, perform corresponding alarm actions according to the alarm information sent by the control unit, and send a control signal to the control unit to stop or start operation.

[0015] According to a second aspect of the present invention, a control method for a frequency converter temperature and humidity control system includes the following steps:

[0016] The control unit controls the inverter to start;

[0017] The control unit reads the ambient temperature, ambient humidity and surface temperature data collected by the detection unit;

[0018] The control unit makes a judgment based on the ambient humidity, and when the ambient humidity value is greater than the humidity threshold, immediately controls the inverter to stop running, and resumes the operation of the inverter after the maintenance is completed;

[0019] The control unit calculates the surface temperature rise value of the capacitor according to the ambient temperature and the surface temperature and makes a judgment. When the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor, the inverter is immediately controlled to stop running. After the maintenance is completed, the operation of the inverter is resumed.

[0020] The control method of the inverter temperature and humidity control system according to the above embodiment of the present invention has at least the following beneficial effects: the control unit calculates the surface temperature rise value of the capacitor and monitors the ambient humidity inside the inverter in real time. When it is found that the surface temperature rise value and the humidity value are both greater than the allowable value, the inverter can be controlled to stop working in time, effectively avoiding explosion accidents and extending the service life of the inverter, thereby bringing long-term economic benefits to users.

[0021] According to a third aspect of the present invention, a control method for a frequency converter temperature and humidity control system includes the following steps:

[0022] The control unit controls the inverter to start;

[0023] The control unit reads the ambient temperature, ambient humidity and surface temperature data collected by the detection unit, and reads the DC bus voltage, load voltage, load torque, load current, output frequency, output power, power semiconductor component temperature and control board temperature data collected by the inverter, and sends all the read data to the human-computer interaction unit for display;

[0024] The control unit makes a judgment based on the ambient humidity. When the ambient humidity value is greater than the humidity threshold, the control unit controls the inverter to stop running and sends a first alarm signal to the human-computer interaction unit. After the maintenance is completed, the operation of the inverter is restored and the first alarm release signal is sent to the human-computer interaction unit.

[0025] The control unit calculates the surface temperature rise value of the capacitor according to the ambient temperature and the surface temperature and sends it to the human-computer interaction unit for display, and makes a judgment according to the surface temperature rise value. When the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor, the inverter is controlled to stop running and a second alarm signal is sent to the human-computer interaction unit. After the maintenance is completed, the operation of the inverter is restored and a second alarm release signal is sent to the human-computer interaction unit.

[0026] The control method of the inverter temperature and humidity control system according to the above embodiment of the present invention has at least the following beneficial effects: the control unit calculates the core temperature rise value of the capacitor and monitors the ambient humidity inside the inverter in real time. When it is found that the surface temperature rise value and the humidity value are both greater than the allowable value, the inverter can be promptly controlled to stop working and send an alarm message to the human-computer interaction unit, thereby promptly reminding the user to handle the fault and avoid machine explosion accidents; at the same time, the user can view the changes in the operating parameters of the inverter through the human-computer interaction unit, which provides data support for timely discovering problems and eliminating faults in the bud.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 It is a structural schematic diagram of a frequency converter temperature and humidity control system according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of installing a K-type thermocouple temperature sensor in an embodiment of the present invention;

[0031] Figure 3 A flow chart of a control method of a first inverter temperature and humidity control system according to an embodiment of the present invention;

[0032] Figure 4 The figure is a flow chart of a control method of a second inverter temperature and humidity control system according to an embodiment of the present invention.

[0033] Reference numerals:

[0034] Detection unit 100, K-type thermocouple temperature sensor 101, thermocouple input module 102, temperature and humidity transmitter 103;

[0035] Inverter 200 , capacitor 300 , control unit 400 , human-machine interaction unit 500 . DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0037] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0039] refer to Figure 1 , is a frequency converter temperature and humidity control system according to an embodiment of the present invention, comprising: a detection unit 100 and a control unit 400. The detection unit 100 is used to collect the ambient temperature and ambient humidity in the frequency converter 200 and the surface temperature of the capacitor 300. The control unit 400 is electrically connected to the detection unit 100 and the frequency converter 200, respectively, and the control unit 400 is used to process the ambient temperature, ambient humidity and surface temperature data collected by the detection unit 100, and send a control signal of stopping or starting to the frequency converter 200 according to the processing result, and the frequency converter 200 parses the control signal to stop or start the operation.

[0040] In some embodiments of the present invention, the detection unit 100 includes: a K-type thermocouple temperature sensor 101, a thermocouple input module 102, and a temperature and humidity transmitter 103. The K-type thermocouple temperature sensor 101 is pasted on the end of the capacitor 300, the thermocouple input module 102 is electrically connected to the control unit 400 and the K-type thermocouple temperature sensor 101, respectively, and the temperature and humidity transmitter 103 is arranged inside the inverter 200 and is electrically connected to the control unit 400. The K-type thermocouple temperature sensor 101 converts the temperature of the measured capacitor 300 into a thermoelectromotive force signal, and the thermocouple input module 102 converts the thermoelectromotive force signal generated by the K-type thermocouple temperature sensor 101 into temperature data and sends it to the control unit 400. The temperature and humidity transmitter 103 converts the ambient temperature and humidity in the inverter 200 into a temperature signal and sends it to the control unit 400.

[0041] In some embodiments of the present invention, the specific model of the K-type thermocouple temperature sensor 101 is RKC ST-50, which is a K-type adhesive temperature sensor launched by RKC Corporation of Japan. Ordinary adhesive thermal resistors or thermocouple temperature sensors cannot be directly used due to the large size of the probe. The appearance of the miniature temperature sensor is only 3-4 mm square. Although it is very suitable for pasting on the end of the capacitor 300, the lead wire is difficult and the output signal needs to be further amplified, so it is not suitable for direct use. The probe part of RKC ST-50 has the following dimensions: width 6.7mm, length 107mm, thickness 0.34mm. It has a glass protective substrate on the outside and a K-type thermocouple wrapped inside. The diameter of the K-type thermocouple is 50μm or 100μm. The capacitor 300 is an electrolytic capacitor, and the diameter of the electrolytic capacitor is generally between 22mm and 64mm. Therefore, RKC ST-50 can be directly used and pasted on the end of the capacitor 300 (such as Figure 2 shown).

[0042] In some embodiments of the present invention, the thermocouple input module 102 and the temperature and humidity transmitter 103 are both electrically connected to the control unit 400 via the MODBUS bus. Compared with other industrial field buses, MODBUS is open for use, supports a wide variety of products, has a mature technical system, and supports more types of physical interfaces, such as RS485 and RS422 interfaces.

[0043] In some embodiments of the present invention, the specific model of the thermocouple input module model is DAM-3037, which is an eight-way thermocouple input module launched by Beijing Altai Technology Development Co., Ltd. When in use, the K-type thermocouple temperature sensor 101 can be connected through a standard length of 1 meter and a model of W-ST50A-1000-Y3 insulating sheath lead wire, and the control unit 400 is communicated with the MODBUS protocol through the built-in RS485 interface. DAM-3037 is installed at a distance of no more than 1 meter from the frequency converter 200 and fixed by a caliper. When necessary, CC1006 type silicone potting glue can be used for auxiliary pasting. The glue has a wide operating temperature range (-50℃~200℃), can be repaired, has high flexibility, and has good dustproof, moisture-proof, shockproof, insulation, thermal conductivity and other advantages. It should be noted that the frequency converters 200 of different powers have different structures of the capacitors 300 in the intermediate circuit, and the natural number is also different, so other multi-way thermocouple input modules can be selected according to actual use requirements.

[0044] In some embodiments of the present invention, the specific model of the temperature and humidity transmitter 103 is TH11S-B, which is a high-precision temperature and humidity transmitter launched by Shenzhen Yingster Technology Co., Ltd., which has the advantages of beautiful and compact appearance, simple wiring, and easy installation. In addition, TH11S-B uses imported high-precision probes to ensure the excellent measurement performance of the product. TH11S-B has its own RS485 interface and can communicate with the control unit 400 using the MODBUS protocol. The temperature and humidity transmitter 103 is installed inside the inverter 200 and needs to be reliably fixed and as far away from the DC bus as possible.

[0045] In some embodiments of the present invention, the control unit 400 is a PLC control module, the PLC control module model is S7-200 SMART, which supports the MODBUS protocol. It should be noted that other microcontrollers can also be used if high reliability, support for the MODBUS protocol, and the number of I / O points are all met.

[0046] In some embodiments of the present invention, the inverter temperature and humidity control system also includes a human-computer interaction unit 500, which can be connected to the control unit 400 through a physical interface such as RJ45, optical fiber, etc. It can display the ambient temperature, ambient humidity, surface temperature and the temperature rise value of the capacitor 300, and can also perform corresponding alarm actions according to the alarm information sent by the control unit 400. The user can remotely control the start and stop of the inverter 200 through the start / stop switch on the human-computer interaction unit 500.

[0047] The present invention proposes a first control method for a frequency converter temperature and humidity control system, such as Figure 3 As shown, the following steps are included:

[0048] The control unit 400 establishes communication with the frequency converter 200, and the control unit 400 controls the frequency converter 200 to start and transmits start-up parameters, wherein the start-up parameters include the output frequency of the frequency converter 200;

[0049] The control unit 400 establishes communication with the detection unit 100 and reads the ambient temperature, ambient humidity and surface temperature data collected by the detection unit 100;

[0050] The control unit 400 makes a judgment based on the ambient humidity. When the ambient humidity value is greater than the humidity threshold, the inverter 200 is immediately controlled to stop running. At this time, the user can blow away the condensed water droplets through preheating to prevent the machine from exploding. After the maintenance is completed, the inverter 200 is restored to run;

[0051] The control unit 400 calculates the surface temperature rise value of the capacitor 300 according to the ambient temperature and the surface temperature and makes a judgment. When the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor 300, the inverter 200 is immediately controlled to stop running. After the maintenance is completed, the operation of the inverter 200 is resumed.

[0052] The present invention proposes a second control method for a frequency converter temperature and humidity control system, such as Figure 4 As shown, the following steps are included:

[0053] The control unit 400 establishes communication with the frequency converter 200, and the control unit 400 controls the frequency converter 200 to start and transmits start-up parameters, wherein the start-up parameters include the output frequency of the frequency converter 200;

[0054] The control unit 400 establishes communication with the detection unit 100, and reads the ambient temperature, ambient humidity and surface temperature data collected by the detection unit 100, and reads the DC bus voltage, load voltage, load torque, load current, output frequency, output power, power semiconductor component temperature and control board temperature data collected by the inverter 200, and sends all the read data to the human-computer interaction unit 500 for display;

[0055] The control unit 400 makes a judgment based on the ambient humidity. When the ambient humidity value is greater than the humidity threshold, the inverter 200 is immediately controlled to stop running. At this time, the user can blow away the condensed water droplets through preheating to prevent the machine from exploding. After the maintenance is completed, the inverter 200 is restored to run;

[0056] The control unit 400 calculates the surface temperature rise value of the capacitor 300 according to the ambient temperature and the surface temperature and sends it to the human-machine interaction unit 500 for display. At the same time, a judgment is made according to the surface temperature rise value. When the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor 300, the control unit 400 controls the inverter 200 to stop running and sends a second alarm signal to the human-machine interaction unit 500. At this time, the human-machine interaction unit 500 performs a corresponding alarm action to remind the user to check the heat dissipation environment or load operation status of the inverter 200 or check the capacity of the capacitor 300, and replace the capacitor 300 if necessary; after the maintenance is completed, the operation of the inverter 200 is restored and the second alarm release signal is sent to the human-machine interaction unit 500. At this time, the human-machine interaction unit 500 releases the corresponding alarm action.

[0057] The humidity in the embodiment of the present invention refers to relative humidity. The relative humidity required for the inverter 200 to work is 5-95%, and the maximum relative humidity required for storage and transportation is also 95%. The relative humidity of the environment for long-term operation should be 40%-90%, preferably maintained at 80%, and condensation is not allowed. In the presence of corrosive gases, the maximum allowable relative humidity is 60%. The preferred humidity threshold in the embodiment of the present invention is 80%.

[0058] The capacitor 300 in the embodiment of the present invention has a rated temperature (referring to the core temperature), and the temperature during actual operation cannot exceed the rated temperature, otherwise the capacitor 300 may be broken down. Due to the different specifications, manufacturers, and manufacturing processes of different capacitors 300, it is difficult to uniformly determine the surface temperature rise limit value, so the ratio of the core temperature rise to the surface temperature rise of the capacitor 300 is obtained through experimental measurement, and then the surface temperature rise limit value is obtained based on the allowable core temperature rise value of the capacitor 300 (i.e., the difference between the rated temperature and the ambient temperature) and the ratio.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0060] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A control method for a frequency converter temperature and humidity control system, characterized in that: The inverter temperature and humidity control system comprises: A detection unit (100) for collecting the ambient temperature and ambient humidity in the frequency converter (200) and the surface temperature of the capacitor (300); a control unit (400) electrically connected to the detection unit (100) and the frequency converter (200) respectively, and used for processing data of the ambient temperature, the ambient humidity and the surface temperature and sending a control signal to the frequency converter (200) to stop or start operation according to the processing result; The detection unit (100) comprises: A K-type thermocouple temperature sensor (101), which is arranged on the capacitor (300); A thermocouple input module (102) electrically connected to the control unit (400) and the K-type thermocouple temperature sensor (101); A temperature and humidity transmitter (103), which is arranged inside the frequency converter (200) and is electrically connected to the control unit (400); The control method of the inverter temperature and humidity control system comprises the following steps: The control unit (400) controls the frequency converter (200) to start; The control unit (400) reads the ambient temperature, ambient humidity and surface temperature data collected by the detection unit (100); The control unit (400) makes a judgment based on the ambient humidity, and when the value of the ambient humidity is greater than a humidity threshold, immediately controls the frequency converter (200) to stop running, and resumes the operation of the frequency converter (200) after the maintenance is completed; The control unit (400) calculates the surface temperature rise value of the capacitor (300) based on the ambient temperature and the surface temperature and makes a judgment; when the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor (300), the inverter (200) is immediately controlled to stop running; after the maintenance is completed, the operation of the inverter (200) is resumed.

2. The control method of the inverter temperature and humidity control system according to claim 1, characterized in that: The K-type thermocouple temperature sensor (101) is RKC ST-50.

3. The control method of the inverter temperature and humidity control system according to claim 2, characterized in that: The thermocouple input module (102) and the temperature and humidity transmitter (103) are both electrically connected to the control unit (400) via a MODBUS bus.

4. The control method of the inverter temperature and humidity control system according to claim 3, characterized in that: The model of the thermocouple input module (102) is DAM-3037.

5. The control method of the inverter temperature and humidity control system according to claim 3, characterized in that: The model of the temperature and humidity transmitter (103) is TH11S-B.

6. The control method of the inverter temperature and humidity control system according to claim 1, characterized in that: The control unit (400) is a PLC control module, and the model of the PLC control module is S7-200SMART.

7. A control method for a frequency converter temperature and humidity control system, characterized in that: The inverter temperature and humidity control system comprises: A detection unit (100) for collecting the ambient temperature and ambient humidity in the frequency converter (200) and the surface temperature of the capacitor (300); a control unit (400) electrically connected to the detection unit (100) and the frequency converter (200) respectively, and used for processing data of the ambient temperature, the ambient humidity and the surface temperature and sending a control signal to the frequency converter (200) to stop or start operation according to the processing result; The detection unit (100) comprises: A K-type thermocouple temperature sensor (101), which is arranged on the capacitor (300); A thermocouple input module (102) electrically connected to the control unit (400) and the K-type thermocouple temperature sensor (101); A temperature and humidity transmitter (103), which is arranged inside the frequency converter (200) and is electrically connected to the control unit (400); The inverter temperature and humidity control system further comprises a human-machine interaction unit (500), the human-machine interaction unit (500) being electrically connected to the control unit (400), and being used for displaying the ambient temperature, ambient humidity, surface temperature and the temperature rise value of the capacitor (300), executing corresponding alarm actions according to the alarm information sent by the control unit (400), and sending a control signal for stopping operation or starting operation to the control unit (400); The control method of the inverter temperature and humidity control system comprises the following steps: The control unit (400) controls the frequency converter (200) to start; The control unit (400) reads the data of the ambient temperature, ambient humidity and surface temperature collected by the detection unit (100), and reads the data of the DC bus voltage, load voltage, load torque, load current, output frequency, output power, power semiconductor element temperature and control board temperature collected by the frequency converter (200), and sends all the read data to the human-computer interaction unit (500) for display; The control unit (400) makes a judgment based on the ambient humidity, and when the value of the ambient humidity is greater than a humidity threshold, controls the frequency converter (200) to stop running and sends a first alarm signal to the human-machine interaction unit (500); after the maintenance is completed, the operation of the frequency converter (200) is resumed and a first alarm release signal is sent to the human-machine interaction unit (500); The control unit (400) calculates the surface temperature rise value of the capacitor (300) according to the ambient temperature and the surface temperature and sends it to the human-machine interaction unit (500) for display, and makes a judgment according to the surface temperature rise value. When the surface temperature rise value is greater than the surface temperature rise limit value of the capacitor (300), the inverter (200) is controlled to stop running and a second alarm signal is sent to the human-machine interaction unit (500). After the maintenance is completed, the operation of the inverter (200) is resumed and a second alarm release signal is sent to the human-machine interaction unit (500).

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