Frequency converter and control method and device thereof, motor, electric device and storage medium

Abstract

The application provides a frequency converter, a control method and device thereof, a motor, a power utilization equipment and a storage medium. The control method of the frequency converter comprises the following steps: determining the power-off duration of the frequency converter based on the Nth time that the frequency converter enters a power-off state; and controlling the frequency converter to work according to the comparison result of the ratio of the power-off duration and a preset duration and a preset threshold, wherein N is a positive integer greater than or equal to 2. The control method of the frequency converter provided by the application determines the power-off duration of the frequency converter when the frequency converter does not enter the power-off state for the first time, and then controls the frequency converter to work according to the comparison result of the ratio of the power-off duration and a preset duration and a preset threshold. In this way, the capacitance value decay degree of the bus capacitor in the frequency converter is monitored based on the power-off duration of the frequency converter, the convenience, timeliness and accuracy of monitoring the capacitance value decay degree of the bus capacitor are ensured, and the use safety and reliability of the frequency converter and the corresponding power utilization equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of bus capacitor status detection technology, and more specifically, to a frequency converter and its control method and device, a motor, electrical equipment and storage medium. Background Technology

[0002] Currently, the health status of bus electrolytic capacitors can be comprehensively assessed using their capacitance and ESR (equivalent series resistance). However, in practical applications, these parameters are difficult to reflect in system monitoring. Consequently, the timeliness and accuracy of monitoring results for bus capacitor health are low, thus reducing the safety and reliability of electrical equipment. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] Therefore, the first aspect of the present invention is to provide a control method for a frequency converter.

[0005] A second aspect of the present invention is to provide a control device for a frequency converter.

[0006] The third aspect of the present invention is to provide a frequency converter.

[0007] The fourth aspect of the present invention is to provide a frequency converter.

[0008] The fifth aspect of the present invention is to provide an electric motor.

[0009] The sixth aspect of the present invention is to provide an electrical device.

[0010] The seventh aspect of the present invention is to provide a readable storage medium.

[0011] In view of this, according to one aspect of the present invention, a control method for a frequency converter is proposed, the control method comprising: determining the power-down duration of the frequency converter based on the Nth time the frequency converter enters a power-down state; and controlling the frequency converter to operate according to a comparison result of the ratio of the power-down duration to a preset duration and a preset threshold; wherein N is a positive integer greater than or equal to 2.

[0012] The execution subject of the inverter control method provided by this invention can be the inverter control device, or it can be determined according to actual usage requirements, and is not specifically limited here. To more clearly describe the inverter control method provided by this invention, the following description uses the inverter control device as the execution subject.

[0013] The inverter control method provided by this invention is used to detect the capacitance decay of the bus electrolytic capacitor in the inverter, i.e., to detect the health status of the bus electrolytic capacitor, and to control the inverter operation based on the detection results. This allows for timely early warning when the bus electrolytic capacitor is in an abnormal state, i.e., when its capacitance decay value is large. It is understood that the bus electrolytic capacitor is one of the key components in the inverter's main circuit, and its health status is a major factor affecting the inverter's lifespan and reliability. Therefore, by detecting the health status of the bus electrolytic capacitor and issuing abnormal alarms, the operational reliability and safety of the inverter, its associated motor, and other electrical equipment can be ensured, thereby guaranteeing the service life of the inverter, motor, and electrical equipment.

[0014] Specifically, in the inverter control method provided by this invention, when the inverter enters the power-down state for the Nth time from the power-on state (i.e., the Nth time the inverter enters the power-off state), the duration of this power-off is obtained. This obtained power-off duration is then compared with a preset duration value to determine the ratio between the current power-off duration and the preset duration. Based on this, a preset threshold is compared with this ratio to determine the health status of the bus electrolytic capacitors in the inverter, i.e., the degree of capacitance attenuation, and the operation of the inverter is controlled based on the comparison result.

[0015] Wherein, N is a positive integer, and N is greater than or equal to 2. That is, when the frequency converter is not entering a power-down state for the first time, its power-down duration is obtained. Based on the comparison between the ratio of this power-down duration to a preset duration and a preset threshold, the health status of the bus electrolytic capacitors in the frequency converter, i.e., the degree of capacitance decay, is determined, and the operation of the frequency converter is controlled. In this way, by monitoring the health status of the bus electrolytic capacitors (i.e., the degree of capacitance decay) through the power-down duration of the frequency converter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors are ensured. This improves the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, thus guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0016] In summary, in the inverter control method proposed in this invention, when the inverter is not entering a power-down state for the first time, its power-down duration is obtained. Based on the comparison between the ratio of this power-down duration to a preset duration and a preset threshold, the health status of the bus electrolytic capacitor in the inverter, i.e., the degree of capacitance decay, is determined. The operation of the inverter is then controlled to provide timely warnings when the bus electrolytic capacitor is in an abnormal state, i.e., when its capacitance decay value is large. Thus, by monitoring the health status (capacitance decay) of the bus electrolytic capacitor through the inverter's power-down duration, the simplicity, timeliness, and accuracy of the monitoring are ensured. This improves the safety and reliability of the inverter, the motor, and the electrical equipment it is connected to, thereby guaranteeing the service life of the inverter, motor, and electrical equipment.

[0017] The control method for the frequency converter according to the present invention may further include the following additional technical features:

[0018] In the above technical solution, determining the power-off duration of the frequency converter specifically includes: determining a first time when the bus voltage of the frequency converter is a first voltage value, and a second time when the bus voltage of the frequency converter is a second voltage value; the difference between the second time and the first time is determined as the power-off duration.

[0019] In this technical solution, when the frequency converter is not entering a power-down state for the first time (i.e., when it is not entering a power-off state for the first time), the power-off time of the frequency converter is started, and the bus voltage of the bus electrolytic capacitor in the frequency converter is detected. Based on this, when the bus voltage of the aforementioned bus electrolytic capacitor reaches a first voltage value, the corresponding first time is obtained; and then when the bus voltage of the aforementioned bus electrolytic capacitor changes to a second voltage value, the corresponding second time is obtained. Based on this, the time difference between the second time and the first time is calculated, and this time difference is determined as the power-off duration of the frequency converter. This allows for subsequent monitoring of the health status of the bus electrolytic capacitor based on the comparison between this power-off duration and a preset duration, thereby controlling the operation of the frequency converter. This ensures the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitor, thereby improving the safety and reliability of the frequency converter and its associated motors and electrical equipment, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0020] It should be noted that the specific values ​​of the first and second voltage values ​​mentioned above can be set according to the actual situation in practical applications, and no specific restrictions are imposed here.

[0021] In any of the above technical solutions, the inverter is controlled to operate based on the comparison result of the ratio of the power outage duration to the preset duration and the preset threshold. Specifically, this includes controlling the inverter to issue an attenuation alarm based on the ratio being less than or equal to the preset threshold.

[0022] In this technical solution, when the inverter is not entering a power-down state for the first time (i.e., when the inverter is not entering a power-off state for the first time), the power-off duration is obtained by measuring the change in the bus voltage of the aforementioned bus electrolytic capacitor. The obtained power-off duration is compared with a preset duration value to determine the ratio between the current power-off duration and the preset duration. Then, a preset threshold is compared with this ratio. If the preset threshold is greater than or equal to the ratio, the inverter is controlled to issue a degradation alarm to promptly inform the user that the capacitance value of the bus electrolytic capacitor in the inverter has degraded significantly and is difficult to maintain normal operation, reminding the user to replace the bus electrolytic capacitor in the inverter. In this way, when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value of the bus electrolytic capacitor is large, an early warning is issued in time, ensuring the timeliness of monitoring the health status of the bus electrolytic capacitor. This improves the safety and reliability of the inverter and the motors and electrical equipment it is connected to, and ensures the service life of the inverter, motors and electrical equipment.

[0023] The aforementioned preset threshold values ​​can specifically be 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, etc. In practical applications, the specific value of the preset threshold can be set according to the actual situation, and no specific restrictions are imposed here.

[0024] In any of the above technical solutions, before determining the power-down duration of the frequency converter based on the Nth power-down of the frequency converter, the control method further includes: detecting the input voltage of the frequency converter based on the frequency converter stopping operation; and determining that the frequency converter has entered a power-down state based on the input voltage being zero.

[0025] In this technical solution, the control method for the aforementioned frequency converter may further include a step of determining whether the frequency converter is in a power-off state based on its operating status and input voltage. Based on this, the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, is monitored by acquiring the power-off duration. Specifically, when monitoring the health status of the bus electrolytic capacitors in the frequency converter, i.e., monitoring the capacitance decay rate, the operating status of the frequency converter can be detected. If the frequency converter is detected to be currently in a shutdown state, its input voltage is monitored. Based on this, if the current input voltage of the frequency converter is detected to be zero, it is considered that the frequency converter has entered a power-off state. At this time, the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, is monitored by acquiring the power-off duration. In this way, the accuracy of determining whether the frequency converter is in a power-off state is ensured by using the operating status and input voltage of the frequency converter. This, in turn, ensures the accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0026] In any of the above technical solutions, the preset duration is the power-off duration when the frequency converter first enters the power-off state.

[0027] In this technical solution, the specific definition of the aforementioned preset duration is defined. Specifically, the preset duration is the power-down duration when the frequency converter first enters the power-down state. This preset duration can be obtained and recorded when the frequency converter first enters the power-down state, so that the obtained initial power-down duration can be stored in the frequency converter's storage area and directly retrieved and used in subsequent processes. This ensures the simplicity and timeliness of monitoring the health status of the bus electrolytic capacitors, thereby ensuring the operational reliability and safety of the frequency converter and the motors and electrical equipment it is connected to, and thus ensuring the service life of the frequency converter, motors, and electrical equipment.

[0028] According to a second aspect of the present invention, a control device for a frequency converter is provided, the device comprising: a control unit for determining the power-down duration of the frequency converter based on the Nth time the frequency converter enters a power-down state; and a control unit for controlling the operation of the frequency converter based on a comparison result of the ratio of the power-down duration to a preset duration and a preset threshold; wherein N is a positive integer greater than or equal to 2.

[0029] The control device for a frequency converter provided by this invention is used to detect the capacitance decay of the bus electrolytic capacitor in the frequency converter, i.e., the health status of the bus electrolytic capacitor, and control the operation of the frequency converter based on the detection results. This allows for timely early warning when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value is large. It is understood that the bus electrolytic capacitor is one of the key components in the main circuit of the frequency converter, and its health status is a major factor affecting the lifespan and reliability of the frequency converter. Therefore, by detecting the health status of the bus electrolytic capacitor and issuing abnormal alarms, the operational reliability and safety of the frequency converter, its associated motor, and other electrical equipment can be ensured, thereby guaranteeing the service life of the frequency converter, motor, and electrical equipment.

[0030] Specifically, in the control device for the frequency converter provided by this invention, when the frequency converter enters the power-down state for the Nth time from the power-on state, that is, when the frequency converter enters the power-off state for the Nth time, the processing unit determines the duration of the power-off. Then, it compares the obtained power-off duration with a preset duration value to determine the duration ratio between the current power-off duration and the preset duration. Based on this, the processing unit compares a preset threshold with this duration ratio to determine the health status of the bus electrolytic capacitors in the frequency converter, that is, the degree of capacitance attenuation of the bus electrolytic capacitors in the frequency converter, according to the comparison result. Finally, the control unit controls the operation of the frequency converter based on the comparison result.

[0031] Wherein, N is a positive integer, and N is greater than or equal to 2. That is, when the frequency converter is not entering a power-down state for the first time, the processing unit determines the power-down duration and, based on the ratio between this power-down duration and a preset duration, compares it with a preset threshold to determine the health status of the bus electrolytic capacitors in the frequency converter, i.e., the degree of capacitance decay. The control unit then controls the operation of the frequency converter. In this way, by monitoring the health status of the bus electrolytic capacitors (i.e., the degree of capacitance decay) through the power-down duration of the frequency converter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors are ensured. This improves the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, thus guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0032] In summary, in the control device for the frequency converter proposed in this invention, when the frequency converter is not entering a power-down state for the first time, the processing unit determines the power-down duration and compares the ratio of this power-down duration to a preset duration with a preset threshold to determine the health status of the bus electrolytic capacitors in the frequency converter, i.e., the degree of capacitance decay. The control unit then controls the operation of the frequency converter to provide timely warnings when the bus electrolytic capacitors are in an abnormal state, i.e., when the capacitance decay value is large. Thus, by monitoring the health status (capacitance decay) of the bus electrolytic capacitors through the power-down duration of the frequency converter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors are ensured. This improves the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, thus guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0033] The control device for the frequency converter according to the present invention may further have the following additional technical features:

[0034] In the above technical solution, the control unit is specifically used to: determine the first time when the bus voltage of the frequency converter is a first voltage value, and the second time when the bus voltage of the frequency converter is a second voltage value; and determine the difference between the second time and the first time as the power outage duration.

[0035] In this technical solution, the specific method for determining the power-down duration of the frequency converter through the processing unit is defined. Specifically, when the frequency converter is not entering the power-down state for the first time (i.e., when the frequency converter is not entering the power-down state for the first time), the power-down time of the frequency converter is started, and the bus voltage of the bus electrolytic capacitor in the frequency converter is detected. Based on this, when the bus voltage of the bus electrolytic capacitor reaches a first voltage value, the corresponding first time is obtained, and then when the bus voltage of the bus electrolytic capacitor changes to a second voltage value, the corresponding second time is obtained. Based on this, the time difference between the second time and the first time is calculated, and this time difference is determined as the power-down duration of the frequency converter for this power-down. This allows for subsequent monitoring of the health status of the bus electrolytic capacitor based on the comparison between this power-down duration and a preset duration, thereby controlling the operation of the frequency converter. This ensures the ease, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the inverter and the motors and electrical equipment they are connected to, and guaranteeing the service life of the inverter, motors, and electrical equipment.

[0036] The specific values ​​of the first voltage value and the second voltage value mentioned above can be set according to the actual situation in practical applications, and no specific restrictions are imposed here.

[0037] In any of the above technical solutions, the control unit is specifically used to: control the frequency converter to issue an attenuation alarm based on the ratio being less than or equal to a preset threshold.

[0038] In this technical solution, when the inverter is not entering a power-down state for the first time (i.e., when the inverter is not entering a power-off state for the first time), the processing unit obtains the power-off duration of the inverter by measuring the change in the bus voltage of the aforementioned bus electrolytic capacitor. The obtained power-off duration is compared with a preset duration value to determine the ratio between the current power-off duration and the preset duration. A preset threshold is then compared with this ratio. If the preset threshold is greater than or equal to the ratio, the control unit controls the inverter to issue a degradation alarm, promptly informing the user that the capacitance of the bus electrolytic capacitor in the inverter has degraded significantly and is difficult to maintain normal operation, thus reminding the user to replace the bus electrolytic capacitor in the inverter. In this way, when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value of the bus electrolytic capacitor is large, an early warning is issued in time, ensuring the timeliness of monitoring the health status of the bus electrolytic capacitor. This improves the safety and reliability of the inverter and the motors and electrical equipment it is connected to, and ensures the service life of the inverter, motors and electrical equipment.

[0039] The aforementioned preset threshold values ​​can specifically be 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, etc. In practical applications, the specific value of the preset threshold can be set according to the actual situation, and no specific restrictions are imposed here.

[0040] In any of the above technical solutions, the control unit is also used to: detect the input voltage of the frequency converter based on the frequency converter stopping operation; and determine that the frequency converter has entered a power-off state based on the input voltage being zero.

[0041] In this technical solution, the aforementioned processing unit can also determine whether the frequency converter is in a power-off state based on its operating status and input voltage. Furthermore, it monitors the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, by acquiring the power-off duration. Specifically, when monitoring the health status of the bus electrolytic capacitors in the frequency converter, i.e., monitoring the capacitance decay rate, the operating status of the frequency converter can be detected. If the frequency converter is detected to be currently in a shutdown state, its input voltage is monitored. Based on this, if the current input voltage of the frequency converter is detected to be zero, it is considered that the frequency converter has entered a power-off state. At this point, the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, is monitored by acquiring the power-off duration. In this way, the accuracy of determining whether the frequency converter is in a power-off state is ensured by using the operating status and input voltage of the frequency converter. This, in turn, ensures the accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0042] In any of the above technical solutions, the preset duration is the power-off duration when the frequency converter first enters the power-off state.

[0043] In this technical solution, the specific definition of the aforementioned preset duration is defined. Specifically, the preset duration is the power-down duration when the frequency converter first enters the power-down state. This preset duration can be obtained and recorded when the frequency converter first enters the power-down state, so that the obtained initial power-down duration can be stored in the frequency converter's storage area and directly retrieved and used in subsequent processes. This ensures the simplicity and timeliness of monitoring the health status of the bus electrolytic capacitors, thereby ensuring the operational reliability and safety of the frequency converter and the motors and electrical equipment it is connected to, and thus ensuring the service life of the frequency converter, motors, and electrical equipment.

[0044] According to a third aspect of the present invention, a frequency converter is provided, comprising: a memory storing a program or instructions; and a processor, which, when executing the program or instructions, implements the steps of the frequency converter control method as described in any of the above-described technical solutions. Therefore, the frequency converter proposed in the third aspect of the present invention possesses all the beneficial effects of the frequency converter control method in any of the technical solutions of the first aspect, which will not be elaborated further here.

[0045] According to a fourth aspect of the present invention, a frequency converter is provided, comprising: a control device for the frequency converter in any of the above-described technical solutions. Therefore, the frequency converter proposed in the fourth aspect of the present invention possesses all the beneficial effects of the control device for the frequency converter in any of the technical solutions of the second aspect, which will not be elaborated further here.

[0046] According to a fifth aspect of the present invention, a motor is provided, comprising the frequency converter described in the third aspect of the technical solution above, or the frequency converter described in the fourth aspect of the technical solution above. Therefore, the motor proposed in the fifth aspect of the present invention possesses all the beneficial effects of the frequency converter described in the third aspect of the technical solution above, or the motor possesses all the beneficial effects of the frequency converter described in the fourth aspect of the technical solution above, which will not be elaborated further here.

[0047] According to a sixth aspect of the present invention, an electrical device is provided, comprising: the motor described in the fifth aspect of the technical solution above. Therefore, the electrical device proposed in the sixth aspect of the present invention possesses all the beneficial effects of the motor described in the fifth aspect of the technical solution above, which will not be elaborated further here.

[0048] The aforementioned electrical equipment is not limited to products such as electric fans, refrigerators, and washing machines, and no specific restrictions are imposed here.

[0049] According to a seventh aspect of the present invention, a readable storage medium is provided on which a program or instructions are stored, which, when executed by a processor, implement the control method of the frequency converter as described in any of the above-described technical solutions. Therefore, the readable storage medium proposed in the seventh aspect of the present invention possesses all the beneficial effects of the control method of the frequency converter in any of the technical solutions of the first aspect described above, and will not be elaborated further here.

[0050] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0051] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0052] Figure 1 One of the flowcharts of the control method of the frequency converter according to an embodiment of the present invention is shown;

[0053] Figure 2 A second schematic flowchart of the control method for a frequency converter according to an embodiment of the present invention is shown;

[0054] Figure 3 The third schematic flowchart of the inverter control method according to an embodiment of the present invention is shown;

[0055] Figure 4 The fourth schematic flowchart of the inverter control method according to an embodiment of the present invention is shown;

[0056] Figure 5 The fifth flowchart illustrates the control method of the frequency converter according to an embodiment of the present invention;

[0057] Figure 6 A structural block diagram of the control device for a frequency converter according to an embodiment of the present invention is shown;

[0058] Figure 7 One of the structural block diagrams of the frequency converter according to an embodiment of the present invention is shown;

[0059] Figure 8 A second structural block diagram of the frequency converter according to an embodiment of the present invention is shown;

[0060] Figure 9 One of the structural block diagrams of the motor according to an embodiment of the present invention is shown;

[0061] Figure 10 A second structural block diagram of the motor according to an embodiment of the present invention is shown;

[0062] Figure 11 This invention illustrates one of the structural block diagrams of an electrical device according to an embodiment of the present invention;

[0063] Figure 12 The second structural block diagram of the electrical equipment according to an embodiment of the present invention is shown. Detailed Implementation

[0064] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0065] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0066] The following is combined Figures 1 to 12 The present application provides a detailed description of the frequency converter, its control method and device, motor, electrical equipment, and storage medium provided in the embodiments of this application through specific implementation methods and application scenarios.

[0067] Example 1, Figure 1 A flowchart illustrating one embodiment of the inverter control method of the present invention is shown. The control method includes the following steps S102 to S108:

[0068] S102, Determine the power-down duration of the inverter based on the Nth time the inverter enters the power-down state;

[0069] S104 controls the inverter to operate based on the comparison result of the ratio of the power outage duration to the preset duration and the preset threshold.

[0070] Where N is a positive integer greater than or equal to 2.

[0071] The inverter control method provided by this invention is used to detect the capacitance decay of the bus electrolytic capacitor in the inverter, i.e., to detect the health status of the bus electrolytic capacitor, and to control the inverter operation based on the detection results. This allows for timely early warning when the bus electrolytic capacitor is in an abnormal state, i.e., when its capacitance decay value is large. It is understood that the bus electrolytic capacitor is one of the key components in the inverter's main circuit, and its health status is a major factor affecting the inverter's lifespan and reliability. Therefore, by detecting the health status of the bus electrolytic capacitor and issuing abnormal alarms, the operational reliability and safety of the inverter, its associated motor, and other electrical equipment can be ensured, thereby guaranteeing the service life of the inverter, motor, and electrical equipment.

[0072] Specifically, in the inverter control method provided by this invention, when the inverter enters the power-down state for the Nth time from the power-on state (i.e., the Nth time the inverter enters the power-off state), the duration of this power-off is obtained. This obtained power-off duration is then compared with a preset duration value to determine the ratio between the current power-off duration and the preset duration. Based on this, a preset threshold is compared with this ratio to determine the health status of the bus electrolytic capacitors in the inverter, i.e., the degree of capacitance attenuation, and the operation of the inverter is controlled based on the comparison result.

[0073] Wherein, N is a positive integer, and N is greater than or equal to 2. That is, when the frequency converter is not entering a power-down state for the first time, its power-down duration is obtained. Based on the comparison between the ratio of this power-down duration to a preset duration and a preset threshold, the health status of the bus electrolytic capacitors in the frequency converter, i.e., the degree of capacitance decay, is determined, and the operation of the frequency converter is controlled. In this way, by monitoring the health status of the bus electrolytic capacitors (i.e., the degree of capacitance decay) through the power-down duration of the frequency converter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors are ensured. This improves the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, thus guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0074] It is understandable that during the power outage of the frequency converter, that is, during the discharge of the bus electrolytic capacitor, there is a specific relationship between the bus voltage (i.e., capacitor voltage), the discharge duration, and the equivalent capacitance value. Specifically, the specific relationship between the bus voltage, discharge time, and equivalent capacitance value of the bus electrolytic capacitor during the discharge process can be expressed by the following formula:

[0075]

[0076] Where Uc(t) is the bus voltage of the bus electrolytic capacitor during the discharge process, U is the bus voltage before the bus electrolytic capacitor discharges (i.e., the bus voltage at t=0), t is the discharge time of the bus electrolytic capacitor, τ is the time constant, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0077] Based on this, by applying and transforming the above formula, we can obtain the following formula:

[0078]

[0079]

[0080] Where t0 is the first discharge time of the bus electrolytic capacitor, t1 is the second discharge time of the bus electrolytic capacitor, U0 is the bus voltage of the bus electrolytic capacitor at time t0, U1 is the bus voltage of the bus electrolytic capacitor at time t1, U is the bus voltage before the bus electrolytic capacitor discharges, T is the discharge time (i.e., power-off time) during which the bus voltage changes from U0 to U1, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0081] Therefore, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. The equivalent capacitance value of the bus electrolytic capacitor and the power-off duration of the inverter exhibit the same changing pattern. Thus, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to its initial capacitance value can be determined by observing the change between the power-off duration of the inverter and a preset duration. This achieves the purpose of monitoring the health status of the bus electrolytic capacitor, i.e., monitoring the degree of capacitance attenuation.

[0082] The initial capacitance value mentioned above refers to the equivalent capacitance value of the bus electrolytic capacitor when the frequency converter first enters the power-down state. In other words, the preset duration is the power-down duration when the frequency converter first enters the power-down state. This preset duration can be obtained and recorded when the frequency converter first enters the power-down state, and stored in the frequency converter's storage area for direct retrieval in subsequent processes. This ensures the simplicity and timeliness of monitoring the health status of the bus electrolytic capacitor, thereby guaranteeing the operational reliability and safety of the frequency converter, its associated motor, and other electrical equipment, ultimately ensuring the service life of the frequency converter, motor, and electrical equipment.

[0083] Specifically, in practical applications, when monitoring the health status of the bus electrolytic capacitors in the frequency converter using the above method—that is, monitoring the capacitance decay of the bus electrolytic capacitors—the operating status and input voltage of the frequency converter can be detected. When the frequency converter is in a stopped state and its input voltage is zero, it is determined that the frequency converter has entered a power-down state. Based on this, the power-down time of the frequency converter is timed, and the bus voltage of the bus electrolytic capacitors in the frequency converter is detected. The first moment when the bus voltage reaches the first voltage value and the second moment when the bus voltage reaches the second voltage value are recorded. Based on this, the number of power-downs of the frequency converter with the current bus electrolytic capacitor is determined. If this is the first power-down of the frequency converter, the initial power-down duration of the frequency converter is obtained (initial power-down duration = second moment - first moment), and this initial power-down duration is recorded and saved for later retrieval and use in the next power-down judgment process. If this power outage is the Nth (N ≥ 2) power outage of the inverter, the duration of this power outage is obtained and compared with the previously saved initial power outage duration. If the ratio of the current power outage duration to the initial power outage duration is less than or equal to a preset threshold, a capacitor attenuation warning is issued so that the user can replace the bus electrolytic capacitor in the inverter in time. If the ratio is greater than the preset threshold, no action is taken and the process proceeds to the next power outage judgment.

[0084] In summary, in the inverter control method proposed in this invention, when the inverter is not entering a power-down state for the first time, its power-down duration is obtained. Based on the comparison between the ratio of this power-down duration to a preset duration and a preset threshold, the health status of the bus electrolytic capacitor in the inverter, i.e., the degree of capacitance decay, is determined. The operation of the inverter is then controlled to provide timely warnings when the bus electrolytic capacitor is in an abnormal state, i.e., when its capacitance decay value is large. Thus, by monitoring the health status (capacitance decay) of the bus electrolytic capacitor through the inverter's power-down duration, the simplicity, timeliness, and accuracy of the monitoring are ensured. This improves the safety and reliability of the inverter, the motor, and the electrical equipment it is connected to, thereby guaranteeing the service life of the inverter, motor, and electrical equipment.

[0085] Example 2, Figure 2 A second schematic flowchart of a frequency converter control method according to an embodiment of the present invention is shown. The control method includes the following steps S202 to S206:

[0086] S202, when the inverter enters the power-off state for the Nth time, the first time when the bus voltage of the inverter is the first voltage value is obtained, and the second time when the bus voltage of the inverter is the second voltage value is obtained;

[0087] S204, the difference between the second time and the first time is determined as the power outage duration;

[0088] S206 compares the ratio of the power outage duration to the preset duration with a preset threshold, and controls the operation of the frequency converter based on the comparison result;

[0089] Where N is a positive integer greater than or equal to 2.

[0090] In this embodiment, based on Embodiment 1, the specific method for obtaining the power-down duration of the frequency converter is further defined. Specifically, when the frequency converter is not entering the power-down state for the first time (i.e., when the frequency converter is not entering the power-down state for the first time), the power-down time of the frequency converter is started, and the bus voltage of the bus electrolytic capacitor in the frequency converter is detected. Based on this, when the bus voltage of the bus electrolytic capacitor reaches a first voltage value, the corresponding first time is obtained, and then when the bus voltage of the bus electrolytic capacitor changes to a second voltage value, the corresponding second time is obtained. Based on this, the time difference between the second time and the first time is calculated, and this time difference is determined as the power-down duration of the frequency converter for this power-down. This allows for subsequent monitoring of the health status of the bus electrolytic capacitor based on the comparison between this power-down duration and a preset duration, thereby controlling the operation of the frequency converter. This ensures the ease, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the inverter and the motors and electrical equipment they are connected to, and guaranteeing the service life of the inverter, motors, and electrical equipment.

[0091] It is understandable that during the power outage of the frequency converter, that is, during the discharge of the bus electrolytic capacitor, there is a specific relationship between the bus voltage (i.e., capacitor voltage), the discharge duration, and the equivalent capacitance value. Specifically, the specific relationship between the bus voltage, discharge time, and equivalent capacitance value of the bus electrolytic capacitor during the discharge process can be expressed by the following formula:

[0092]

[0093]

[0094] Where t0 is the first discharge time of the bus electrolytic capacitor, t1 is the second discharge time of the bus electrolytic capacitor, U0 is the bus voltage of the bus electrolytic capacitor at time t0, U1 is the bus voltage of the bus electrolytic capacitor at time t1, U is the bus voltage before the bus electrolytic capacitor discharges, T is the discharge time (i.e., power-off time) during which the bus voltage changes from U0 to U1, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0095] Therefore, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. The equivalent capacitance value of the bus electrolytic capacitor and the power-off duration of the inverter exhibit the same changing pattern. Thus, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to its initial capacitance value can be determined by observing the change between the power-off duration of the inverter and a preset duration. This achieves the purpose of monitoring the health status of the bus electrolytic capacitor, i.e., monitoring the degree of capacitance attenuation.

[0096] In addition, it should be noted that the specific values ​​of the first voltage value and the second voltage value mentioned above can be set according to the actual situation in practical applications, and no specific restrictions are imposed here.

[0097] Example 3, Figure 3 A third schematic flowchart of the inverter control method according to an embodiment of the present invention is shown. The control method includes the following steps S302 to S304:

[0098] S302, determine the power-down duration of the inverter when the inverter enters the power-down state for the Nth time;

[0099] S304: If the preset threshold is greater than or equal to the ratio of the power outage duration to the preset duration, the inverter will be controlled to trigger an attenuation alarm.

[0100] Where N is a positive integer greater than or equal to 2.

[0101] In this embodiment, based on the above embodiment, the specific method of controlling the operation of the frequency converter is further defined by comparing the ratio of the power-down duration of the frequency converter to a preset duration with a preset threshold. Specifically, when the frequency converter is not entering the power-down state for the first time (i.e., when the frequency converter is not entering the power-down state for the first time), the power-down duration of the frequency converter is obtained by measuring the change in the bus voltage of the bus electrolytic capacitor. The obtained power-down duration is compared with the preset duration value to determine the ratio of the power-down duration of the frequency converter to the preset duration. Then, the preset threshold is compared with the duration ratio. If the preset threshold is greater than or equal to the duration ratio, the frequency converter is controlled to issue a degradation alarm to promptly inform the user that the capacitance value of the bus electrolytic capacitor in the frequency converter has a high degree of degradation and is difficult to maintain normal operation, reminding the user to replace the bus electrolytic capacitor in the frequency converter. In this way, when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value of the bus electrolytic capacitor is large, an early warning is issued in time, ensuring the timeliness of monitoring the health status of the bus electrolytic capacitor. This improves the safety and reliability of the inverter and the motors and electrical equipment it is connected to, and ensures the service life of the inverter, motors and electrical equipment.

[0102] It is understandable that when the bus electrolytic capacitor is in a discharging state, that is, when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. Specifically, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be expressed by the following formula:

[0103]

[0104]

[0105] Wherein, C0 is the initial equivalent capacitance value of the bus electrolytic capacitor, that is, the equivalent capacitance value determined when the inverter first loses power, C is the equivalent capacitance value determined when the inverter does not lose power for the first time, R is the equivalent discharge resistance, T0 is the power-off duration when the inverter loses power for the first time, that is, the preset duration mentioned above, T is the power-off duration when the inverter does not lose power for the first time, U0 is the first voltage value mentioned above, and U1 is the second voltage value mentioned above.

[0106] Therefore, it can be seen that the equivalent capacitance value of the bus electrolytic capacitor and the power-down duration of the frequency converter exhibit the same variation law. Specifically, the ratio of the aforementioned equivalent capacitance value to the initial equivalent capacitance value is equal to the ratio of the aforementioned power-down duration to the preset duration, that is, the aforementioned... Therefore, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to the initial equivalent capacitance value can be determined by the ratio between the power-down time of the frequency converter and the preset time.

[0107] Specifically, if the preset threshold is greater than or equal to the ratio between the power outage duration and the preset duration, it is considered that the equivalent capacitance value of the bus electrolytic capacitor has significantly decreased compared to its initial equivalent capacitance value, making it difficult to maintain normal operation. In this case, the frequency converter will issue an attenuation alarm to promptly inform the user of the abnormal situation of the bus electrolytic capacitor and remind the user to replace the bus electrolytic capacitor in the frequency converter.

[0108] Additionally, it should be noted that the aforementioned preset threshold values ​​can specifically be 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, etc. In practical applications, the specific value of the aforementioned preset threshold can be set according to the actual situation, and no specific restrictions are imposed here.

[0109] Example 4, Figure 4 A fourth schematic flowchart of a frequency converter control method according to an embodiment of the present invention is shown. The control method includes the following steps S402 to S408:

[0110] S402 detects the input voltage of the frequency converter when the frequency converter is stopped.

[0111] S404 indicates that the inverter has entered a power-down state when the input voltage is zero.

[0112] S406 determines the power-off duration of the frequency converter;

[0113] S408 compares the ratio of the power outage duration to the preset duration with a preset threshold, and controls the operation of the frequency converter based on the comparison result.

[0114] In this embodiment, the control method for the frequency converter may further include a step of determining whether the frequency converter is in a power-off state based on its operating status and input voltage. Based on this, the health status of the bus electrolytic capacitor, i.e., the capacitance decay, is monitored by acquiring the power-off duration. Specifically, when monitoring the health status of the bus electrolytic capacitor in the frequency converter, i.e., monitoring the capacitance decay, the operating status of the frequency converter can be detected. If the frequency converter is detected to be currently in a shutdown state, its input voltage is monitored. Based on this, if the current input voltage of the frequency converter is detected to be zero, it is considered that the frequency converter has entered a power-off state. At this time, the health status of the bus electrolytic capacitor, i.e., the capacitance decay, is monitored by acquiring the power-off duration. In this way, the accuracy of determining whether the frequency converter is in a power-off state is ensured by using the operating status and input voltage of the frequency converter. This, in turn, ensures the accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0115] It is understandable that in practical applications, many factors can cause a frequency converter to enter a shutdown state, such as power failure at the front end or component damage. Therefore, in the control method proposed in this invention, an input voltage is introduced. Only when the frequency converter is in a shutdown state and its input voltage is zero is it determined that the frequency converter has entered a power failure state, thus ensuring the accuracy of the power failure state determination.

[0116] Example 5, Figure 5 Fifthly, a flowchart illustrating the control method of a frequency converter according to an embodiment of the present invention is shown. The control method includes the following steps S502 to S520:

[0117] S502, the frequency converter has entered the shutdown state;

[0118] S504: The software checks whether the input voltage is 0. If it is, then execute S506; otherwise, execute S504.

[0119] S506: The software checks whether the bus voltage is equal to U0. If yes, it executes S508; otherwise, it executes S506.

[0120] S508, record the initial time t0;

[0121] S510: The software checks whether the bus voltage is equal to U1. If yes, it executes S512; otherwise, it executes S510.

[0122] S512, record the cutoff time t1;

[0123] S514: Is this the first power-on / power-off of the frequency converter? If yes, proceed to S516; otherwise, proceed to S518.

[0124] S516, save T0 = t1 - t0;

[0125] S518, calculate whether the power outage time T = t1 - t0 is less than or equal to 0.8 × T0. If yes, execute S520; otherwise, execute S502.

[0126] S520, report capacitor degradation warning.

[0127] Wherein, U0 is the first voltage value, U1 is the second voltage value, T0 is the power-off duration when the inverter first loses power, i.e. the preset duration, T is the power-off duration when the inverter does not lose power for the first time, t0 is the first time when the bus voltage of the bus electrolytic capacitor is U0, and t1 is the second time when the bus voltage of the bus electrolytic capacitor is U1.

[0128] Further, in this embodiment, the aforementioned preset threshold is 0.8. Based on this, when monitoring the health status of the bus electrolytic capacitor in the inverter, i.e., monitoring the capacitance decay of the bus electrolytic capacitor, the operating status and input voltage of the inverter can be detected. When the inverter is in a stopped state and its input voltage is zero, it is determined that the inverter has entered a power-down state. Based on this, the power-down time of the inverter is timed, and the bus voltage of the bus electrolytic capacitor in the inverter is detected. The first time t0 when the bus voltage is the first voltage value U0, and the second time t1 when the bus voltage is the second voltage value U1 are recorded. Based on this, the number of power-downs of the inverter with the current bus electrolytic capacitor is determined. If this power-down is the first power-down of the inverter, the initial power-down duration T0 of the inverter is obtained, T0 = t1 - t0, and this initial power-down duration T0 is recorded and saved for later retrieval and use in the next power-down judgment process. If this power outage is the Nth (N ≥ 2) power outage of the frequency converter, the duration of this power outage, T, is obtained, where T = t1 - t0. This power outage duration T is compared with the previously saved initial power outage duration T0. If the power outage duration T ≤ 0.8 × T0, a capacitor attenuation warning is issued so that the user can replace the bus electrolytic capacitor in the frequency converter in time. If the power outage duration T > 0.8 × T0, no action is taken and the process proceeds to the next power outage judgment.

[0129] Example 6, Figure 6A structural block diagram of a control device 600 for a frequency converter according to an embodiment of the present invention is shown. The control device includes a processing unit 602 and a control unit 604.

[0130] Processing unit 602 is used to determine the power-down duration of the inverter based on the Nth time the inverter enters the power-down state;

[0131] Control unit 604 is used to control the operation of the frequency converter based on the comparison result of the ratio of the power failure duration to the preset duration and the preset threshold.

[0132] Where N is a positive integer greater than or equal to 2.

[0133] The control device 600 for a frequency converter provided by this invention is used to detect the capacitance decay of the bus electrolytic capacitor in the frequency converter, i.e., to detect the health status of the bus electrolytic capacitor, and to control the operation of the frequency converter based on the detection results. This allows for timely warnings when the bus electrolytic capacitor is in an abnormal state, i.e., when its capacitance decay value is large. It is understood that the bus electrolytic capacitor is one of the key components in the main circuit of the frequency converter, and its health status is a major factor affecting the lifespan and reliability of the frequency converter. Therefore, by detecting the health status of the bus electrolytic capacitor and issuing abnormal alarms, the operational reliability and safety of the frequency converter, its associated motor, and other electrical equipment can be ensured, thereby guaranteeing the service life of the frequency converter, motor, and electrical equipment.

[0134] Specifically, in the control device 600 for the frequency converter provided by this invention, when the frequency converter enters the power-down state for the Nth time from the power-on state, that is, when the frequency converter enters the power-off state for the Nth time, the processing unit 602 determines the duration of the power-off, and then compares the obtained power-off duration with a preset duration value to determine the duration ratio between the current power-off duration and the preset duration. Based on this, the processing unit 602 compares a preset threshold with this duration ratio to determine the health status of the bus electrolytic capacitor in the frequency converter, that is, the degree of capacitance attenuation of the bus electrolytic capacitor in the frequency converter, according to the comparison result. Then, the control unit 604 controls the operation of the frequency converter according to the comparison result.

[0135] Wherein, N is a positive integer, and N is greater than or equal to 2. That is, when the frequency converter is not entering a power-down state for the first time, the processing unit 602 determines the power-down duration, and based on the comparison between the ratio of this power-down duration and a preset duration and a preset threshold, determines the health status of the bus electrolytic capacitors in the frequency converter, i.e., the degree of capacitance decay, and controls the operation of the frequency converter through the control unit 604. In this way, by monitoring the health status of the bus electrolytic capacitors (i.e., the degree of capacitance decay) through the power-down duration of the frequency converter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors are ensured, thereby improving the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0136] It is understandable that during the power outage of the frequency converter, that is, during the discharge of the bus electrolytic capacitor, there is a specific relationship between the bus voltage (i.e., capacitor voltage), the discharge duration, and the equivalent capacitance value. Specifically, the specific relationship between the bus voltage, discharge time, and equivalent capacitance value of the bus electrolytic capacitor during the discharge process can be expressed by the following formula:

[0137]

[0138] Where Uc(t) is the bus voltage of the bus electrolytic capacitor during the discharge process, U is the bus voltage before the bus electrolytic capacitor discharges (i.e., the bus voltage at t=0), t is the discharge time of the bus electrolytic capacitor, τ is the time constant, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0139] Based on this, by applying and transforming the above formula, we can obtain the following formula:

[0140]

[0141]

[0142] Where t0 is the first discharge time of the bus electrolytic capacitor, t1 is the second discharge time of the bus electrolytic capacitor, U0 is the bus voltage of the bus electrolytic capacitor at time t0, U1 is the bus voltage of the bus electrolytic capacitor at time t1, U is the bus voltage before the bus electrolytic capacitor discharges, T is the discharge time (i.e., power-off time) during which the bus voltage changes from U0 to U1, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0143] Therefore, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. The equivalent capacitance value of the bus electrolytic capacitor and the power-off duration of the inverter exhibit the same changing pattern. Thus, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to its initial capacitance value can be determined by observing the change between the power-off duration of the inverter and a preset duration. This achieves the purpose of monitoring the health status of the bus electrolytic capacitor, i.e., monitoring the degree of capacitance attenuation.

[0144] The initial capacitance value mentioned above refers to the equivalent capacitance value of the bus electrolytic capacitor when the frequency converter first enters the power-down state. In other words, the preset duration is the power-down duration when the frequency converter first enters the power-down state. This preset duration can be obtained and recorded when the frequency converter first enters the power-down state, and stored in the frequency converter's storage area for direct retrieval in subsequent processes. This ensures the simplicity and timeliness of monitoring the health status of the bus electrolytic capacitor, thereby guaranteeing the operational reliability and safety of the frequency converter, its associated motor, and other electrical equipment, ultimately ensuring the service life of the frequency converter, motor, and electrical equipment.

[0145] Specifically, in practical applications, when monitoring the health status of the bus electrolytic capacitors in the frequency converter using the above method—that is, monitoring the capacitance decay of the bus electrolytic capacitors—the operating status and input voltage of the frequency converter can be detected. When the frequency converter is in a stopped state and its input voltage is zero, it is determined that the frequency converter has entered a power-down state. Based on this, the power-down time of the frequency converter is timed, and the bus voltage of the bus electrolytic capacitors in the frequency converter is detected. The first moment when the bus voltage reaches the first voltage value and the second moment when the bus voltage reaches the second voltage value are recorded. Based on this, the number of power-downs of the frequency converter with the current bus electrolytic capacitor is determined. If this is the first power-down of the frequency converter, the initial power-down duration of the frequency converter is obtained (initial power-down duration = second moment - first moment), and this initial power-down duration is recorded and saved for later retrieval and use in the next power-down judgment process. If this power outage is the Nth (N ≥ 2) power outage of the inverter, the duration of this power outage is obtained and compared with the previously saved initial power outage duration. If the ratio of the current power outage duration to the initial power outage duration is less than or equal to a preset threshold, a capacitor attenuation warning is issued so that the user can replace the bus electrolytic capacitor in the inverter in time. If the ratio is greater than the preset threshold, no action is taken and the process proceeds to the next power outage judgment.

[0146] In summary, in the inverter control device 600 proposed in this invention, when the inverter is not entering a power-down state for the first time, the processing unit 602 determines the power-down duration and, based on the comparison between the ratio of the power-down duration and a preset duration and a preset threshold, determines the health status of the bus electrolytic capacitor in the inverter, i.e., the degree of capacitance decay. The control unit 604 then controls the operation of the inverter to provide timely warnings when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value is large. Thus, by monitoring the health status of the bus electrolytic capacitor, i.e., the degree of capacitance decay, through the power-down duration of the inverter, the simplicity, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitor are ensured. This improves the safety and reliability of the inverter and the motors and electrical equipment it is connected to, and guarantees the service life of the inverter, motors, and electrical equipment.

[0147] In Example 7, based on Example 6, the processing unit 602 is further configured to: determine a first time when the bus voltage of the frequency converter is a first voltage value, and a second time when the bus voltage of the frequency converter is a second voltage value; and determine the difference between the second time and the first time as the power outage duration.

[0148] In this embodiment, the specific method for determining the power-down duration of the frequency converter by the processing unit 602 is defined. Specifically, when the frequency converter is not entering the power-down state for the first time (i.e., when the frequency converter is not entering the power-down state for the first time), the power-down time of the frequency converter is started, and the bus voltage of the bus electrolytic capacitor in the frequency converter is detected. Based on this, when the bus voltage of the bus electrolytic capacitor reaches a first voltage value, the corresponding first time is obtained, and when the bus voltage of the bus electrolytic capacitor changes to a second voltage value, the corresponding second time is obtained. Based on this, the time difference between the second time and the first time is calculated, and this time difference is determined as the power-down duration of the frequency converter for this power-down. This allows for subsequent monitoring of the health status of the bus electrolytic capacitor based on the comparison between this power-down duration and a preset duration, thereby controlling the operation of the frequency converter. This ensures the ease, timeliness, and accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the inverter and the motors and electrical equipment they are connected to, and guaranteeing the service life of the inverter, motors, and electrical equipment.

[0149] It is understandable that during the power outage of the frequency converter, that is, during the discharge of the bus electrolytic capacitor, there is a specific relationship between the bus voltage (i.e., capacitor voltage), the discharge duration, and the equivalent capacitance value. Specifically, the specific relationship between the bus voltage, discharge time, and equivalent capacitance value of the bus electrolytic capacitor during the discharge process can be expressed by the following formula:

[0150]

[0151]

[0152] Where t0 is the first discharge time of the bus electrolytic capacitor, t1 is the second discharge time of the bus electrolytic capacitor, U0 is the bus voltage of the bus electrolytic capacitor at time t0, U1 is the bus voltage of the bus electrolytic capacitor at time t1, U is the bus voltage before the bus electrolytic capacitor discharges, T is the discharge time (i.e., power-off time) during which the bus voltage changes from U0 to U1, R is the equivalent discharge resistance, and C is the equivalent capacitance value of the bus electrolytic capacitor.

[0153] Therefore, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. The equivalent capacitance value of the bus electrolytic capacitor and the power-off duration of the inverter exhibit the same changing pattern. Thus, when the bus electrolytic capacitor is in a discharging state, i.e., when the inverter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to its initial capacitance value can be determined by observing the change between the power-off duration of the inverter and a preset duration. This achieves the purpose of monitoring the health status of the bus electrolytic capacitor, i.e., monitoring the degree of capacitance attenuation.

[0154] In addition, it should be noted that the specific values ​​of the first voltage value and the second voltage value mentioned above can be set according to the actual situation in practical applications, and no specific restrictions are imposed here.

[0155] Example 8: Based on the above examples, the control unit 604 is further configured to: control the frequency converter to issue an attenuation alarm when the ratio of the power failure duration to the preset duration is less than a preset threshold.

[0156] In this embodiment, the control unit 604 defines the specific method by which it controls the operation of the frequency converter by comparing the ratio of the power-down duration of the frequency converter to a preset duration with a preset threshold. Specifically, when the frequency converter is not entering a power-down state for the first time (i.e., when the frequency converter is not entering a power-down state for the first time), the processing unit 602 obtains the power-down duration of the frequency converter by measuring the change in the bus voltage of the bus electrolytic capacitor, and compares the obtained power-down duration with a preset duration value to determine the ratio of the power-down duration of the frequency converter to the preset duration. Then, it compares the preset threshold with the duration ratio. If the preset threshold is greater than or equal to the duration ratio, the control unit 604 controls the frequency converter to issue a degradation alarm, so as to inform the user in a timely manner that the capacitance value of the bus electrolytic capacitor in the frequency converter is highly degraded and it is difficult to maintain a normal working state, reminding the user to replace the bus electrolytic capacitor in the frequency converter. In this way, when the bus electrolytic capacitor is in an abnormal state, i.e., when the capacitance decay value of the bus electrolytic capacitor is large, an early warning is issued in time, ensuring the timeliness of monitoring the health status of the bus electrolytic capacitor. This improves the safety and reliability of the inverter and the motors and electrical equipment it is connected to, and ensures the service life of the inverter, motors and electrical equipment.

[0157] It is understandable that when the bus electrolytic capacitor is in a discharging state, that is, when the inverter is in a power-off state, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be represented by the power-off duration of the inverter. Specifically, the equivalent capacitance value of the bus electrolytic capacitor in the inverter can be expressed by the following formula:

[0158]

[0159]

[0160] Wherein, C0 is the initial equivalent capacitance value of the bus electrolytic capacitor, that is, the equivalent capacitance value determined when the inverter first loses power, C is the equivalent capacitance value determined when the inverter does not lose power for the first time, R is the equivalent discharge resistance, T0 is the power-off duration when the inverter loses power for the first time, that is, the preset duration mentioned above, T is the power-off duration when the inverter does not lose power for the first time, U0 is the first voltage value mentioned above, and U1 is the second voltage value mentioned above.

[0161] Therefore, it can be seen that the equivalent capacitance value of the bus electrolytic capacitor and the power-down duration of the frequency converter exhibit the same variation law. Specifically, the ratio of the aforementioned equivalent capacitance value to the initial equivalent capacitance value is equal to the ratio of the aforementioned power-down duration to the preset duration, that is, the aforementioned... Therefore, the degree of attenuation of the equivalent capacitance value of the bus electrolytic capacitor compared to the initial equivalent capacitance value can be determined by the ratio between the power-down time of the frequency converter and the preset time.

[0162] Specifically, if the preset threshold is greater than or equal to the ratio between the power outage duration and the preset duration, it is considered that the equivalent capacitance value of the bus electrolytic capacitor has significantly decreased compared to its initial equivalent capacitance value, making it difficult to maintain normal operation. In this case, the frequency converter will issue an attenuation alarm to promptly inform the user of the abnormal situation of the bus electrolytic capacitor and remind the user to replace the bus electrolytic capacitor in the frequency converter.

[0163] Additionally, it should be noted that the aforementioned preset threshold values ​​can specifically be 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, etc. In practical applications, the specific value of the aforementioned preset threshold can be set according to the actual situation, and no specific restrictions are imposed here.

[0164] In Example 9, based on the above examples, the processing unit 602 can further be used to: detect the input voltage of the frequency converter when the frequency converter stops running; and determine that the frequency converter has entered a power-off state when the input voltage is zero.

[0165] In this embodiment, the processing unit 602 can further determine whether the inverter is in a power-off state based on the inverter's operating status and input voltage. Based on this, it monitors the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, by acquiring the power-off duration. Specifically, when monitoring the health status of the bus electrolytic capacitors in the inverter, i.e., monitoring the capacitance decay rate, the inverter's operating status can be detected. If the inverter is detected to be currently in a shutdown state, its input voltage is monitored. Based on this, if the inverter's current input voltage is detected to be zero, it is considered that the inverter has entered a power-off state. At this time, the health status of the bus electrolytic capacitors, i.e., the capacitance decay rate, is monitored by acquiring the power-off duration. In this way, the accuracy of determining whether the frequency converter is in a power-off state is ensured by using the operating status and input voltage of the frequency converter. This, in turn, ensures the accuracy of monitoring the health status of the bus electrolytic capacitors, thereby improving the safety and reliability of the frequency converter and the motors and electrical equipment it is connected to, and guaranteeing the service life of the frequency converter, motors, and electrical equipment.

[0166] It is understandable that in practical applications, many factors can cause a frequency converter to enter a shutdown state, such as power failure at the front end or component damage. Therefore, in the control device proposed in this invention, an input voltage is introduced. Only when the processing unit 602 determines that the frequency converter is in a shutdown state and its input voltage is zero, is it determined that the frequency converter has entered a power failure state, thus ensuring the accuracy of the power failure state determination.

[0167] Example 10, Figure 7 A structural block diagram of a frequency converter 700 provided in an embodiment of the present invention is shown.

[0168] The frequency converter 700 includes:

[0169] Memory 702, on which programs or instructions are stored;

[0170] The processor 704 executes the above-described program or instructions to implement the steps of the inverter control method as described in any of the above embodiments.

[0171] The inverter 700 provided in this embodiment includes a memory 702 and a processor 704. When the program or instructions in the memory 702 are executed by the processor 704, they implement the steps of the inverter control method as described in any of the above embodiments. Therefore, the inverter 700 has all the beneficial effects of the inverter control method in any of the above embodiments, which will not be repeated here.

[0172] Specifically, the memory 702 and the processor 704 can be connected via a bus or other means. The processor 704 may include one or more control units, and the processor 704 may be a chip such as a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA).

[0173] Example 11, Figure 8 A structural block diagram of a frequency converter 800 provided in an embodiment of the present invention is shown, wherein the frequency converter 800 includes: a control device 600 of the frequency converter in any of the above embodiments.

[0174] The frequency converter 800 provided in this embodiment includes the control device 600 of the frequency converter in any of the above embodiments. Therefore, the frequency converter 800 has all the beneficial effects of the control device 600 of the frequency converter in any of the above embodiments, which will not be repeated here.

[0175] Example 12, Figure 9 A structural block diagram of a motor 900 provided in an embodiment of the present invention is shown. The motor 900 includes the frequency converter 700 described in the above embodiment.

[0176] The motor 900 provided in this embodiment includes the frequency converter 700 in the above embodiments. Therefore, the motor 900 possesses all the technical effects of the frequency converter 700 in the above embodiments, which will not be repeated here.

[0177] Example 13, Figure 10 A structural block diagram of a motor 1000 provided in an embodiment of the present invention is shown. The motor 1000 includes the frequency converter 800 described in the above embodiment.

[0178] The motor 1000 provided in this embodiment includes the frequency converter 800 in the above embodiments. Therefore, the motor 1000 possesses all the technical effects of the frequency converter 800 in the above embodiments, which will not be repeated here.

[0179] Example 14, Figure 11 A structural block diagram of an electrical device 1100 provided in an embodiment of the present invention is shown. The electrical device 1100 includes the motor 900 described in the above embodiment.

[0180] The electrical device 1100 provided in this embodiment includes the motor 900 in the above embodiments. Therefore, the electrical device 1100 possesses all the technical effects of the motor 900 in the above embodiments, which will not be repeated here.

[0181] Example 15, Figure 12 A structural block diagram of an electrical appliance 1200 provided in an embodiment of the present invention is shown. The electrical appliance 1200 includes the motor 1000 described in the above embodiment.

[0182] The electrical equipment 1200 provided in this embodiment includes the motor 1000 in the above embodiments. Therefore, the electrical equipment 1200 possesses all the technical effects of the motor 1000 in the above embodiments, which will not be repeated here.

[0183] It should be noted that the electrical equipment proposed in the embodiments of the present invention includes, but is not limited to, the following products: electric fans, refrigerators, and washing machines, which will not be listed here one by one.

[0184] Example sixteen, an embodiment of the seventh aspect of the present invention, provides a readable storage medium. A program or instructions are stored thereon, which, when executed by a processor, implement the steps of the inverter control method as described in any of the above embodiments.

[0185] The readable storage medium provided in this embodiment of the invention stores programs or instructions that, when executed by a processor, can implement the steps of the inverter control method as described in any of the above embodiments. Therefore, this readable storage medium possesses all the beneficial effects of the inverter control method in any of the above embodiments, which will not be elaborated further here.

[0186] Specifically, the aforementioned readable storage medium can include any medium capable of storing or transmitting information. Examples of readable storage media include electronic circuits, semiconductor memory devices, read-only memory (ROM), random access memory (RAM), compact disc read-only memory (CD-ROM), flash memory, erasable ROM (EROM), magnetic tape, floppy disk, optical disk, hard disk, fiber optic media, radio frequency (RF) links, optical data storage devices, etc. Code segments can be downloaded via computer networks such as the Internet and intranets.

[0187] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, unless otherwise expressly specified and limited. The terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0188] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0189] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0190] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for a frequency converter, characterized in that, include: The power-down duration of the frequency converter is determined based on the Nth time the frequency converter enters the power-down state. The inverter is controlled to operate based on the comparison between the ratio of the power outage duration to the preset duration and the preset threshold. Where N is a positive integer greater than or equal to 2; Before determining the power outage duration of the frequency converter based on the Nth power outage of the frequency converter, the control method further includes: Based on the inverter stopping operation, the input voltage of the inverter is detected; Based on the fact that the input voltage is zero, it is determined that the frequency converter has entered a power-off state; Among them, when the frequency converter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the frequency converter's bus electrolytic capacitor compared to the initial capacitance value is determined by the change between the power-off duration of the frequency converter and the preset duration. Determining the power-off duration of the frequency converter specifically includes: The first time when the bus voltage of the frequency converter is determined to be a first voltage value, and the second time when the bus voltage of the frequency converter is determined to be a second voltage value; The difference between the second time and the first time is determined as the power outage duration; Specifically, in the case of the inverter losing power for the first time, the initial power-down duration of the inverter is obtained, recorded and saved for subsequent retrieval and use, and used in the next power-down judgment process.

2. The control method for the frequency converter according to claim 1, characterized in that, The step of controlling the inverter to operate based on the comparison result of the ratio of the power outage duration to the preset duration and the preset threshold specifically includes: Based on the ratio being less than or equal to the preset threshold, the frequency converter is controlled to issue an attenuation alarm.

3. The control method for the frequency converter according to claim 1 or 2, characterized in that, The preset duration is the power-off duration when the frequency converter first enters the power-off state.

4. A control device for a frequency converter, characterized in that, include: The control unit is used to determine the power-off duration of the frequency converter based on the Nth time the frequency converter enters the power-off state; The control unit is used to control the inverter to operate based on the comparison result of the ratio of the power outage duration to the preset duration and the preset threshold. Where N is a positive integer greater than or equal to 2; The control unit is also used for: Based on the inverter stopping operation, the input voltage of the inverter is detected; Based on the fact that the input voltage is zero, it is determined that the frequency converter has entered a power-off state; Among them, when the frequency converter is in a power-off state, the degree of attenuation of the equivalent capacitance value of the frequency converter's bus electrolytic capacitor compared to the initial capacitance value is determined by the change between the power-off duration of the frequency converter and the preset duration. The control unit is specifically used for: The first time when the bus voltage of the frequency converter is determined to be a first voltage value, and the second time when the bus voltage of the frequency converter is determined to be a second voltage value; The difference between the second time and the first time is determined as the power outage duration; Specifically, in the case of the inverter losing power for the first time, the initial power-down duration of the inverter is obtained, recorded and saved for subsequent retrieval and use, and used in the next power-down judgment process.

5. The control device for the frequency converter according to claim 4, characterized in that, The control unit is specifically used for: Based on the ratio being less than or equal to the preset threshold, the frequency converter is controlled to issue an attenuation alarm.

6. The control device for the frequency converter according to claim 4 or 5, characterized in that, The preset duration is the power-off duration when the frequency converter first enters the power-off state.

7. A frequency converter, characterized in that, include: Memory, which stores programs or instructions; A processor that, when executing the program or instructions, implements the steps of the control method for the frequency converter as described in any one of claims 1 to 3.

8. A frequency converter, characterized in that, include: The control device for the frequency converter as described in any one of claims 4 to 6.

9. An electric motor, characterized in that, include: The frequency converter as described in claim 7 or 8.

10. An electrical appliance, characterized in that, include: The motor as described in claim 9.

11. A readable storage medium having a program or instructions stored thereon, characterized in that, When the program or instructions are executed by the processor, they implement the steps of the control method for the frequency converter as described in any one of claims 1 to 3.

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