Variable frequency motor rotating speed control method and device, variable frequency motor, compressor and air conditioner

Abstract

The application discloses a variable frequency motor rotating speed control method and device, a variable frequency motor, a compressor and an air conditioner, relates to the field of air conditioners, and solves the problem that resonance is caused by critical rotating speed in the speed regulation process of a variable frequency motor in the prior art. The variable frequency motor rotating speed control method comprises the following steps: obtaining real-time rotating speed and initial critical rotating speed of the variable frequency motor; comparing the real-time rotating speed of the variable frequency motor with the initial critical rotating speed; when the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is within a preset range, adjusting the real-time rotating speed of the variable frequency motor, and making the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed be outside the preset range. The method can avoid the variable frequency motor running at or near the initial critical rotating speed, thereby effectively avoiding the resonance caused by the critical rotating speed in the speed regulation process of the variable frequency motor, achieving the purpose of motor shock absorption and noise reduction, and effectively improving the service life of the variable frequency motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the air conditioning technical field, especially to a variable frequency motor speed control method and device, a variable frequency motor, a compressor and an air conditioner. BACKGROUND

[0002] With the market demand for air conditioner energy efficiency is higher and higher, commercial screw, centrifugal large central air conditioning also launched variable frequency unit, and the market penetration rate of variable frequency unit is also higher and higher. Variable frequency unit adjusts the speed of permanent magnet synchronous variable frequency motor through pressure and frequency regulation, so as to adjust the refrigerating capacity of the unit, ensure that the refrigerating capacity of the unit matches the demand refrigerating capacity, and achieve the purpose of energy saving. It can be seen that in order to ensure that the refrigerating capacity of the unit matches the demand refrigerating capacity, the speed of the permanent magnet synchronous variable frequency motor needs to be continuously adjusted between 0 and rated speed, and there is a possibility of keeping a certain speed for a long time.

[0003] The rotor itself has a natural resonance frequency. When the vibration frequency of the rotor reaches the resonance frequency point or multiple of the resonance frequency point during rotation, resonance phenomenon will occur, and the speed point at this time is the critical speed point. Due to the existence of the critical speed of the motor rotor, the permanent magnet synchronous variable frequency motor will run at its critical speed for a long time during speed regulation, and the motor rotor will resonate at the critical speed, causing the rotor to vibrate violently, which seriously affects the service life of the rotor and related bearings and other components.

[0004] Therefore, it becomes a technical problem to be solved by those skilled in the art to provide a technology that can effectively avoid resonance of the variable frequency motor caused by critical speed during speed regulation. SUMMARY

[0005] One of the purposes of the present application is to provide a variable frequency motor speed control method, which solves the technical problem of resonance of the variable frequency motor caused by critical speed during speed regulation in the prior art. The many technical effects produced by the preferred technical solution of the present application are described in detail below.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The variable frequency motor speed control method of the present application comprises the following steps:

[0008] Obtaining the real-time speed and the initial critical speed of the variable frequency motor;

[0009] Comparing the real-time speed of the variable frequency motor with the initial critical speed;

[0010] When the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is within the preset range, the real-time rotating speed of the variable frequency motor is adjusted so that the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is outside the preset range.

[0011] According to a preferred embodiment, when the real-time rotating speed of the variable frequency motor is equal to the initial critical rotating speed, the real-time rotating speed of the variable frequency motor is adjusted so that the real-time rotating speed of the variable frequency motor is greater than the initial critical rotating speed or the real-time rotating speed of the variable frequency motor is less than the initial critical rotating speed.

[0012] According to a preferred embodiment, the step of obtaining the initial critical rotating speed of the variable frequency motor comprises the following steps:

[0013] When the variable frequency motor is started for the first time, the rotating speed of the variable frequency motor is gradually increased from zero to the rated rotating speed;

[0014] The vibration amplitude of the variable frequency motor at each rotating speed is obtained;

[0015] The rotating speed at which the vibration amplitude of the variable frequency motor is maximum is recorded, and this rotating speed is the initial critical rotating speed of the variable frequency motor.

[0016] According to a preferred embodiment, the variable frequency motor rotating speed control method further comprises the step of correcting the initial critical rotating speed.

[0017] According to a preferred embodiment, the step of correcting the initial critical rotating speed comprises the following steps:

[0018] The rotating speed of the variable frequency motor is gradually increased from zero to the rated rotating speed, the real-time vibration amplitude of the variable frequency motor at each rotating speed is obtained, and the real-time critical rotating speed at which the real-time vibration amplitude is maximum is determined;

[0019] The real-time critical rotating speed is compared with the initial critical rotating speed of the variable frequency motor;

[0020] If the relative error between the real-time critical rotating speed and the initial critical rotating speed of the variable frequency motor exceeds the error setting value, the real-time critical rotating speed is determined as the current critical rotating speed of the variable frequency motor.

[0021] According to a preferred embodiment, if the real-time critical rotating speed is different from the initial critical rotating speed of the variable frequency motor, the real-time critical rotating speed is determined as the current critical rotating speed of the variable frequency motor.

[0022] The variable frequency motor rotating speed control method provided by the application has at least the following beneficial technical effects:

[0023] The variable frequency motor rotating speed control method of the application comprises the following steps: obtaining the real-time rotating speed and the initial critical rotating speed of the variable frequency motor, comparing the real-time rotating speed of the variable frequency motor with the initial critical rotating speed, adjusting the real-time rotating speed of the variable frequency motor when the relative error of the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is within a preset range, and making the relative error of the real-time rotating speed of the variable frequency motor and the initial critical rotating speed be outside the preset range. The variable frequency motor can be prevented from running at or near the initial critical rotating speed, thereby effectively avoiding the resonance caused by the initial critical rotating speed in the speed regulation process of the variable frequency motor, achieving the purpose of motor shock absorption and noise reduction, and effectively improving the service life of the variable frequency motor. That is, the variable frequency motor rotating speed control method of the application solves the technical problem of resonance caused by the critical rotating speed in the speed regulation process of the variable frequency motor in the prior art.

[0024] A second object of the application is to provide a variable frequency motor rotating speed control device.

[0025] The variable frequency motor rotating speed control device of the application comprises:

[0026] The obtaining module is configured to obtain the real-time rotating speed and the initial critical rotating speed of the variable frequency motor.

[0027] The comparison module is configured to compare the real-time rotating speed of the variable frequency motor with the initial critical rotating speed.

[0028] The adjustment module is configured to adjust the real-time rotating speed of the variable frequency motor when the relative error of the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is within a preset range, and make the relative error of the real-time rotating speed of the variable frequency motor and the initial critical rotating speed be outside the preset range.

[0029] The variable frequency motor rotating speed control device provided by the application has at least the following beneficial technical effects:

[0030] The variable frequency motor rotating speed control device of the application can realize variable frequency motor rotating speed control through the functions of the obtaining module, the comparison module and the adjustment module, can prevent the variable frequency motor from running at or near the initial critical rotating speed, thereby effectively avoiding the resonance caused by the initial critical rotating speed in the speed regulation process of the variable frequency motor, achieving the purpose of motor shock absorption and noise reduction, and effectively improving the service life of the variable frequency motor.

[0031] A third object of the application is to provide a variable frequency motor.

[0032] The variable frequency motor of the present application comprises a motor body, a frequency converter, a vibration tester and a controller, wherein the vibration tester is arranged on the bearing of the rotor of the variable frequency motor, the vibration tester is used for monitoring the vibration of the rotor of the variable frequency motor, the frequency converter is connected with the motor body, the controller is connected with the frequency converter and the vibration tester, and the controller is used for executing a program to realize the steps of the variable frequency motor speed control method according to any one of the technical solutions of the present application.

[0033] The variable frequency motor provided by the present application has at least the following beneficial technical effects:

[0034] The variable frequency motor of the present application comprises a controller used for executing a program to realize the steps of the variable frequency motor speed control method according to any one of the technical solutions of the present application, so that the variable frequency motor speed control can be realized, the variable frequency motor is prevented from running at or near the initial critical speed, and thus the resonance caused by the initial critical speed during the speed regulation process of the variable frequency motor can be effectively avoided, the purpose of motor shock absorption and noise reduction is achieved, and the working life of the variable frequency motor can be effectively improved.

[0035] The fourth object of the present application is to provide a compressor.

[0036] The compressor of the present application comprises the variable frequency motor according to any one of the technical solutions of the present application.

[0037] The compressor provided by the present application has at least the following beneficial technical effects:

[0038] The compressor of the present application comprises the variable frequency motor according to any one of the technical solutions of the present application, and since the variable frequency motor has the advantages of shock absorption, noise reduction and working life improvement, the performance of the compressor of the present application can be improved.

[0039] The fifth object of the present application is to provide an air conditioner.

[0040] The air conditioner of the present application comprises the compressor according to any one of the technical solutions of the present application.

[0041] The air conditioner provided by the present application has at least the following beneficial technical effects:

[0042] The air conditioner of the present application comprises the compressor according to any one of the technical solutions of the present application, and since the performance of the compressor is improved, the performance of the air conditioner of the present application can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the protection scope of the present application.

[0044] Figure 1 is a schematic diagram of the relationship between the rotating speed and the amplitude;

[0045] Figure 2 is a flow chart of the preferred embodiment of the variable frequency motor rotating speed control method of the present application;

[0046] Figure 3 is a flow chart of another preferred embodiment of the variable frequency motor rotating speed control method of the present application;

[0047] Figure 4 is a schematic diagram of the present application when the real-time critical rotating speed appears a deviation;

[0048] Figure 5 is a flow chart of the preferred embodiment of the method for correcting the initial critical rotating speed of the present application;

[0049] Figure 6 is a module diagram of the preferred embodiment of the variable frequency motor rotating speed control device of the present application;

[0050] Figure 7 is a module diagram of the preferred embodiment of the variable frequency motor of the present application;

[0051] Figure 8 is a schematic diagram of the structure of the preferred embodiment of the compressor of the present application.

[0052] In the drawings: 101, acquisition module; 102, comparison module; 103, adjustment module; 201, motor body; 202, frequency converter; 203, vibration tester; 204, controller; 205, rotor; 2051, bearing. DETAILED DESCRIPTION

[0053] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the protection scope of the present application.

[0054] The variable frequency motor rotating speed control method, device, variable frequency motor, compressor and air conditioner of the present application will be described in detail below in combination with the accompanying drawings of the specification and embodiments 1-5. Figures 1-8 The variable frequency motor rotating speed control method, device, variable frequency motor, compressor and air conditioner of the present application will be described in detail below in combination with the accompanying drawings of the specification and embodiments 1-5.

[0055] Example 1

[0056] This embodiment provides a detailed description of the variable frequency motor speed control method of the present invention.

[0057] Figure 1 The graph showing the relationship between rotational speed and amplitude is presented. For example... Figure 1 As described above, the rotor's amplitude increases with increasing rotational speed. At a certain speed, the amplitude reaches its maximum value (response occurs). Beyond this speed, the amplitude gradually decreases with increasing speed and stabilizes within a certain range. The speed corresponding to this maximum rotor amplitude is called the rotor's critical speed. When the rotational speed continues to increase, approaching twice the critical speed, the amplitude again increases with increasing speed. When the rotational speed equals twice the critical speed, it is called the second-order critical speed. This pattern continues with the third-order, fourth-order, and so on. The rotor's critical speed depends on the lateral stiffness coefficient of the rotor shaft, the mass of the disk, and the magnitude of the axial force acting on the shaft. Therefore, different motor rotors have different critical speeds. Even for the same type of motor, differences in manufacturing, processing, and installation can lead to different critical speeds for the rotor.

[0058] Figure 2 A flowchart of a preferred embodiment of the variable frequency motor control method of this example is shown. Figure 2 As shown, the variable frequency motor speed control method of this embodiment includes the following steps:

[0059] Step 1: Obtain the real-time speed and initial critical speed of the variable frequency motor.

[0060] Step 2: Compare the real-time speed of the variable frequency motor with the initial critical speed.

[0061] Step 3: When the relative error between the real-time speed of the variable frequency motor and the initial critical speed is within a preset range, adjust the real-time speed of the variable frequency motor so that the relative error between the real-time speed and the initial critical speed is outside the preset range. For example, the preset range is 3%. That is, when the difference between the real-time speed and the initial critical speed divided by the initial critical speed is within 3%, adjust the real-time speed of the variable frequency motor so that the difference between the real-time speed and the initial critical speed divided by the initial critical speed is greater than 3%.

[0062] Preferably, when the real-time speed of the variable frequency motor is the same as the initial critical speed, the real-time speed of the variable frequency motor is adjusted to either be greater than the initial critical speed or less than the initial critical speed. Specifically, the real-time speed of the variable frequency motor is adjusted by regulating the output of the frequency converter 202.

[0063] When the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is outside the preset range, it indicates that the variable frequency motor is not running at or near the initial critical rotating speed, and thus there is no need to adjust the real-time rotating speed of the variable frequency motor.

[0064] The variable frequency motor rotating speed control method of the embodiment includes obtaining the real-time rotating speed and the initial critical rotating speed of the variable frequency motor, comparing the real-time rotating speed of the variable frequency motor with the initial critical rotating speed, and adjusting the real-time rotating speed of the variable frequency motor when the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed is within the preset range. The step of making the relative error between the real-time rotating speed of the variable frequency motor and the initial critical rotating speed outside the preset range can avoid the variable frequency motor running at or near the initial critical rotating speed, thereby effectively avoiding the resonance of the variable frequency motor caused by the initial critical rotating speed in the speed regulation process, achieving the purpose of motor shock absorption and noise reduction, and effectively improving the service life of the variable frequency motor. That is, the variable frequency motor rotating speed control method of the embodiment solves the technical problem of resonance of the variable frequency motor caused by the critical rotating speed in the speed regulation process in the prior art.

[0065] According to a preferred embodiment, obtaining the initial critical rotating speed of the variable frequency motor includes the following steps: when the variable frequency motor is started for the first time, gradually increasing the rotating speed of the variable frequency motor from zero to the rated rotating speed; obtaining the vibration amplitude of the variable frequency motor at each rotating speed; and recording the rotating speed at which the vibration amplitude of the variable frequency motor is maximum, which is the initial critical rotating speed of the variable frequency motor, as shown in FIG. 1. Figure 3 Preferably, the initial critical rotating speed of the variable frequency motor includes the first-order initial critical rotating speed, the second-order initial critical rotating speed, and the N-order initial critical rotating speed within the rated rotating speed of the variable frequency motor.

[0066] Since the initial critical rotating speed of the motor rotor of the variable frequency motor is determined after the variable frequency motor is manufactured. The variable frequency motor rotating speed control method of the preferred technical solution of the embodiment gradually increases the rotating speed of the variable frequency motor from zero to the rated rotating speed when the variable frequency motor is started for the first time, records the vibration amplitude of the variable frequency motor at each rotating speed in the process, and determines the rotating speed at which the vibration amplitude of the variable frequency motor is maximum, which is the initial critical rotating speed of the variable frequency motor. The variable frequency motor rotating speed control method of the preferred technical solution of the embodiment can provide an accurate basis for subsequent control of the rotating speed of the variable frequency motor by determining the initial critical rotating speed of the variable frequency motor.

[0067] According to a preferred embodiment, the variable frequency motor rotating speed control method further includes the step of correcting the initial critical rotating speed. Figure 5 A flowchart of the preferred embodiment of the method for correcting the initial critical rotating speed of the embodiment is shown in FIG. 2. Figure 5As shown, the step of correcting the initial critical speed includes the following steps: gradually increasing the speed of the variable frequency motor from zero to the rated speed, obtaining the real-time vibration amplitude of the variable frequency motor at each speed, and determining the real-time critical speed when the real-time vibration amplitude is maximum; comparing the real-time critical speed with the initial critical speed of the variable frequency motor; if the relative error of the real-time critical speed and the initial critical speed of the variable frequency motor exceeds the relative error setting value, determining the real-time critical speed as the current critical speed of the variable frequency motor. If the relative error of the real-time critical speed and the initial critical speed of the variable frequency motor is within the error setting value range, it indicates that the initial critical speed of the variable frequency motor has not deviated and does not need to be corrected.

[0068] Preferably, the relative error setting value can be 1%, but is not limited thereto, and can also be other setting values. More preferably, the error setting value is 0, that is, when the real-time critical speed is less than the initial critical speed of the variable frequency motor, and the real-time critical speed is greater than the initial critical speed of the variable frequency motor, the real-time critical speed is determined as the current critical speed of the variable frequency motor. Figure 4 A schematic diagram of the real-time critical speed deviation of the embodiment is shown. As shown in FIG. 2, the initial critical speed of the variable frequency motor deviates, which can be a positive deviation (i.e., the real-time critical speed is greater than the initial critical speed of the variable frequency motor) or a negative deviation (i.e., the real-time critical speed is less than the initial critical speed of the variable frequency motor). Figure 4

[0069] The components such as the motor rotor and the bearing are continuously aging after a long time of operation, and the vibration characteristics thereof change over time after maintenance or replacement. The variable frequency motor speed control method of the preferred technical solution of the embodiment further includes the step of correcting the initial critical speed. When it is found that the deviation of the initial critical speed exceeds the error setting value, the initial critical speed is corrected, so that the resonance caused by the initial critical speed can be avoided during the operation of the variable frequency motor, the purpose of motor shock absorption and noise reduction is achieved, and the working life of the variable frequency motor can be effectively improved.

[0070] Embodiment 2

[0071] The variable frequency motor speed control device of the embodiment is described in detail.

[0072] The variable frequency motor speed control device of the embodiment includes an obtaining module 101, a comparison module 102, and an adjusting module 103, as shown in FIG. 3. Preferably, the obtaining module 101 is used to obtain the real-time speed and the initial critical speed of the variable frequency motor; the comparison module 102 is used to compare the real-time speed of the variable frequency motor with the initial critical speed; and the adjusting module 103 is used to adjust the real-time speed of the variable frequency motor when the relative error of the real-time speed of the variable frequency motor and the initial critical speed is within the preset range, and to make the relative error of the real-time speed of the variable frequency motor and the initial critical speed outside the preset range. Figure 6 ​​

[0073] The variable frequency motor speed control device of the embodiment can realize variable frequency motor speed control, avoid the variable frequency motor running at or near the initial critical speed, effectively avoid the resonance caused by the initial critical speed in the speed regulation process of the variable frequency motor, achieve the purpose of motor shock absorption and noise reduction, and effectively improve the service life of the variable frequency motor.

[0074] Embodiment 3

[0075] The variable frequency motor of the embodiment is described in detail.

[0076] The variable frequency motor of the embodiment includes a motor body 201, a frequency converter 202, a vibration tester 203, and a controller 204, as shown in Figure 7 Preferably, the vibration tester 203 is arranged on the bearing 2051 of the rotor 205 of the variable frequency motor, the vibration tester 203 is used to monitor the vibration of the rotor 205 of the variable frequency motor, the frequency converter 202 is connected with the motor body 201, the controller 204 is connected with the frequency converter 202 and the vibration tester 203, and the controller 204 is used to execute a program to realize the steps of the variable frequency motor speed control method of any one of the technical solutions in Embodiment 1, as shown in Figure 7 and Figure 8 The frequency converter 202 is used to drive the motor body 201 to run. Preferably, the variable frequency motor of the embodiment is a permanent magnet synchronous variable frequency motor.

[0077] The variable frequency motor of the embodiment includes the controller 204 used to execute a program to realize the steps of the variable frequency motor speed control method of any one of the technical solutions in Embodiment 1, so that the variable frequency motor speed control can be realized, the variable frequency motor can be avoided to run at or near the initial critical speed, the resonance caused by the initial critical speed in the speed regulation process of the variable frequency motor can be effectively avoided, the purpose of motor shock absorption and noise reduction can be achieved, and the service life of the variable frequency motor can be effectively improved.

[0078] Embodiment 4

[0079] The compressor of the embodiment is described in detail.

[0080] The compressor of the embodiment includes the variable frequency motor of any one of the technical solutions in Embodiment 3, as shown in Figure 8 The remaining structure of the compressor can be the same as the prior art, and will not be described here.

[0081] The compressor of the embodiment includes the variable frequency motor of any one of the technical solutions in Embodiment 3, and the variable frequency motor has the advantages of shock absorption, noise reduction, and service life improvement, so that the performance of the compressor of the embodiment can be improved.

[0082] Embodiment 5

[0083] The air conditioner of the present application is described in detail in this embodiment.

[0084] The air conditioner of this embodiment includes the compressor of any one of the technical solutions in Embodiment 4. The remaining structure of the air conditioner can be the same as the prior art, and will not be described here.

[0085] The air conditioner of this embodiment includes the compressor of any one of the technical solutions in Embodiment 4. Due to the improved performance of the compressor, the performance of the air conditioner of this embodiment can be improved.

[0086] It can be understood that the same or similar parts in the above embodiments can be mutually referred to, and the content not described in detail in some embodiments can be referred to the same or similar content in other embodiments.

[0087] It should be noted that in the description of the present application, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" or "multiple" is at least two.

[0088] It should be understood that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or a middle element can be present at the same time; when an element is referred to as "connected" to another element, it can be directly connected to the other element or a middle element can be present at the same time, in addition, "connected" used herein can include wireless connection; the phrase "and / or" used herein includes any unit and all combinations of the associated listed items.

[0089] Any process or method descriptions in flow charts or otherwise described herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for performing specific logic functions or steps in the process, and the various embodiments of the present application include additional implementations in which the order of steps can be different, including use of the same or different code modules, segments, or portions of code, and the described processes can be performed in an order different than that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as will be understood by those having ordinary skill in the art.

[0090] It should be understood that each part of the present application can be realized by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be realized by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if realized by hardware, and as in another embodiment, it can be realized by any one or a combination of the following technologies known in the art: discrete logic circuit with logic gate circuit for implementing logic function on data signal, application specific integrated circuit with suitable combination logic gate circuit, programmable gate array (PGA), field programmable gate array (FPGA) and the like.

[0091] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment method can be completed by a program instructing the relevant hardware, and the program can be stored in a computer readable storage medium, and when executed, includes one or a combination of steps of the embodiment method.

[0092] In addition, each functional unit in each embodiment of the present application can be integrated into one processing module, or each unit can exist physically, or two or more units can be integrated into one module. The above-mentioned integrated module can be realized in the form of hardware or in the form of software functional module. The integrated module, if realized in the form of software functional module and sold or used as an independent product, can also be stored in a computer readable storage medium.

[0093] The above-mentioned storage medium can be a read-only memory, a magnetic disk or an optical disk, etc.

[0094] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above-mentioned terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0095] Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A method for controlling the speed of a variable frequency motor, characterized in that, Includes the following steps: Obtain the real-time speed and initial critical speed of the variable frequency motor; The real-time speed of the variable frequency motor is compared with the initial critical speed; When the relative error between the real-time speed of the variable frequency motor and the initial critical speed is within the preset range, adjust the real-time speed of the variable frequency motor so that the relative error between the real-time speed of the variable frequency motor and the initial critical speed is outside the preset range. It also includes the step of correcting the initial critical speed; Correcting the initial critical speed involves the following steps: The speed of the variable frequency motor is gradually increased from zero to the rated speed. The real-time vibration amplitude of the variable frequency motor at each speed is obtained, and the real-time critical speed at which the real-time vibration amplitude is the largest is determined. The real-time critical speed is compared with the initial critical speed of the variable frequency motor. If the relative error between the real-time critical speed and the initial critical speed of the variable frequency motor exceeds the error setting value, the real-time critical speed is determined as the current critical speed of the variable frequency motor.

2. The variable frequency motor speed control method according to claim 1, characterized in that, When the real-time speed of the variable frequency motor is the same as the initial critical speed, adjust the real-time speed of the variable frequency motor to make it greater than the initial critical speed, or make it less than the initial critical speed.

3. The variable frequency motor speed control method according to claim 1, characterized in that, Obtaining the initial critical speed of a variable frequency motor includes the following steps: When the variable frequency motor is started for the first time, the speed of the variable frequency motor is gradually increased from zero to the rated speed. Obtain the vibration amplitude of the variable frequency motor at various speeds; Record the rotational speed at which the vibration amplitude of the variable frequency motor is at its maximum. This rotational speed is the initial critical speed of the variable frequency motor.

4. The variable frequency motor speed control method according to claim 1, characterized in that, If the real-time critical speed is different from the initial critical speed of the variable frequency motor, the real-time critical speed is determined as the current critical speed of the variable frequency motor.

5. A variable frequency motor speed control device, characterized in that, For implementing the variable frequency motor speed control method according to any one of claims 1-4, the control device comprises: The acquisition module is used to acquire the real-time speed and initial critical speed of the variable frequency motor; The comparison module is used to compare the real-time speed of the variable frequency motor with the initial critical speed. The adjustment module is used to adjust the real-time speed of the variable frequency motor when the relative error between the real-time speed and the initial critical speed is within a preset range, and to keep the relative error between the real-time speed and the initial critical speed outside the preset range.

6. A variable frequency motor, characterized in that, include: The system comprises a motor body, a frequency converter, a vibration tester, and a controller. The vibration tester is mounted on the bearing of the variable frequency motor rotor and is used to monitor the vibration of the rotor. The frequency converter is connected to the motor body. The controller is connected to the frequency converter and the vibration tester, and the controller is used to execute a program to implement the steps of the variable frequency motor speed control method according to any one of claims 1 to 4.

7. A compressor, characterized in that, Including the variable frequency motor as described in claim 6.

8. An air conditioner, characterized in that, Includes the compressor described in claim 7.

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