Motor restart control method and device, computer equipment and storage medium

Abstract

The invention relates to the technical field of motor control, and provides a motor restart control method and device, computer equipment and a storage medium. The method comprises the following steps: acquiring a residual magnetism voltage amplitude of a motor during shutdown; determining the rotor frequency of the motor based on the residual magnetism voltage amplitude; under the condition that the rotor frequency is not changed, the residual magnetism voltage amplitude is increased to the preset frequency converter voltage amplitude according to a preset first step length; and controlling the motor to start again by using a preset frequency converter voltage amplitude and the rotor frequency. According to the motor restart control method provided by the invention, the current impact during motor restart can be reduced.

Description

Technical Field

[0001] This application relates to the technical field of motor control, and particularly to a control method, device, computer device and storage medium for motor restart. Background Art

[0002] In industrial applications, momentary loss of input power, i.e., momentary power failure or voltage sag, usually occurs. When the momentary loss of input power occurs, the motor may stop running immediately.

[0003] Due to the large inertia of the motor, the motor will still rotate for a long time after stopping. In scenarios that require frequent start and stop, the motor needs to come to a complete stop before it can be restarted, otherwise it will cause a large current impact, resulting in overcurrent or overload faults, affecting work efficiency, and seriously damaging the frequency converter in severe cases. Therefore, related technologies usually calculate the rotor frequency by converting a sine wave into a square wave when there is residual magnetism in the motor.

[0004] However, related technologies only consider the angle and frequency of the residual magnetism voltage but not the amplitude of the residual magnetism voltage when the residual magnetism voltage is large. In the case of no residual magnetism condition, the rotational speed calculation may be incorrect due to a small torque calculation, and thus the restart current impact will be large. Summary of the Invention

[0005] Embodiments of this application provide a control method, device, computer device and storage medium for motor restart, aiming to solve the technical problem of restart current impact caused by inaccurate rotational speed calculation in related technologies.

[0006] In a first aspect, embodiments of this application provide a control method for motor restart, the method including:

[0007] Obtain the amplitude of the residual magnetism voltage of the motor when it stops;

[0008] Based on the amplitude of the residual magnetism voltage, determine the rotor frequency of the motor;

[0009] When the rotor frequency remains unchanged, increase the amplitude of the residual magnetism voltage to the preset amplitude of the frequency converter voltage in accordance with a preset first step length;

[0010] Use the preset amplitude of the frequency converter voltage and the rotor frequency to control the motor to start again.

[0011] A further technical solution thereof is that the obtaining the amplitude of the residual magnetism voltage of the motor when it stops includes:

[0012] Obtain the phase voltage of the motor;

[0013] Based on the phase voltage, obtain the amplitude of the residual magnetism voltage of the motor when it stops.

[0014] A further technical solution is that determining the rotor frequency of the motor based on the residual magnetism voltage amplitude includes:

[0015] Judging whether the residual magnetism voltage amplitude meets a first preset requirement;

[0016] If the residual magnetism voltage amplitude meets the first preset requirement, the residual magnetism voltage amplitude of the motor at shutdown is obtained based on the phase voltage;

[0017] If the residual magnetism voltage amplitude does not meet the first preset requirement, the stator of the motor is excited until it is determined that the voltage amplitude after excitation meets the first preset requirement, and then the residual magnetism voltage amplitude of the motor at shutdown is obtained based on the phase voltage.

[0018] A further technical solution is that the exciting the stator of the motor until it is determined that the voltage amplitude after excitation meets the first preset requirement includes:

[0019] Gradually increasing the voltage of the stator of the motor from zero voltage and determining the current amplitude after excitation;

[0020] When the current amplitude after excitation meets a second preset requirement, the motor is decreased from the default stator frequency to obtain a decreased stator frequency;

[0021] Judging whether the decreased stator frequency meets an excitation stop instruction;

[0022] If the decreased stator frequency meets the excitation stop instruction, it is determined that the voltage amplitude after excitation meets the first preset requirement, the excitation operation of the stator of the motor is stopped, and the voltage amplitude after excitation is used as the residual magnetism voltage amplitude.

[0023] A further technical solution is that the judging whether the decreased stator frequency meets the excitation stop instruction includes:

[0024] Obtaining the power change rate of the motor;

[0025] Judging whether the power change rate of the motor is zero;

[0026] If the power change rate of the motor is zero, it is determined that the decreased stator frequency meets the excitation stop instruction.

[0027] A further technical solution is that the obtaining the power change rate of the motor includes:

[0028] Obtaining the power of the motor and the cut-off frequency of the high-pass filter;

[0029] Based on the power of the motor and the cut-off frequency of the high-pass filter, obtaining the power change rate of the motor.

[0030] A further technical solution thereof is that obtaining the power of the motor includes:

[0031] Obtaining the excitation voltage, excitation current and power factor of the motor;

[0032] Based on the excitation voltage, the excitation current and the power factor, obtaining the power of the motor.

[0033] In a second aspect, an embodiment of the present application further provides a control device for motor restart, which includes a unit for executing the above method.

[0034] In a third aspect, an embodiment of the present application further provides a computer device, which includes a memory and a processor. A computer program is stored on the memory, and when the processor executes the computer program, the above method is implemented.

[0035] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium. The storage medium stores a computer program, and when the computer program is executed by a processor, the above method can be implemented.

[0036] An embodiment of the present application provides a control method, device, computer device and storage medium for motor restart. Among them, the method includes: obtaining the residual magnetism voltage amplitude of the motor when it stops; determining the rotor frequency of the motor based on the residual magnetism voltage amplitude; when the rotor frequency remains unchanged, increasing the residual magnetism voltage amplitude to the preset inverter voltage amplitude according to a preset first step length; using the preset inverter voltage amplitude and the rotor frequency to control the motor to start again. In the embodiment of the present application, since the residual magnetism voltage amplitude of the motor when it stops is obtained and the residual magnetism voltage amplitude is increased to the preset inverter voltage amplitude, that is, the residual magnetism voltage amplitude inside the motor is matched with the output voltage amplitude of the inverter (i.e., the preset inverter voltage amplitude), current impact caused by voltage difference can be avoided; and when the rotor frequency remains unchanged, the residual magnetism voltage amplitude is gradually increased according to the preset first step length, so that the motor can smoothly transition to the normal operation state, and further, current impact caused by voltage mutation can be effectively avoided. Description of the Drawings

[0037] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0038] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] One or more embodiments are exemplarily illustrated by the pictures in the corresponding accompanying drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements, unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0040] Figure 1 Schematic flowchart of the first embodiment of a control method for motor restart provided by the present application;

[0041] Figure 2 Schematic diagram of the images of power, frequency, and slip provided by the embodiments of the present application;

[0042] Figure 3 Schematic diagram of the structure of a computer device provided by the embodiments of the present application. Detailed implementation manners

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0044] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0045] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0046] It should also be understood that the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. As used in the specification of this application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0047] It should be further understood that the term "and / or" used in the specification of this application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0048] As used in this specification and the appended claims, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrases "if determined" or "if [the described condition or event] is detected" can be interpreted as meaning "once determined", "in response to determining", "once [the described condition or event] is detected", or "in response to detecting [the described condition or event]" depending on the context.

[0049] In industrial application scenarios, momentary loss of input power, i.e., momentary power failure or voltage sag, usually occurs. When momentary loss of input power occurs, the motor may stop running immediately.

[0050] Due to the relatively large inertia of the motor, the motor will still rotate for a long time after stopping. In scenarios where frequent start and stop are required, the motor needs to come to a complete stop before it can be restarted, otherwise it will cause a large current impact, resulting in overcurrent or overload faults, affecting work efficiency, and seriously damaging the frequency converter in severe cases. Therefore, related technologies usually calculate the rotor frequency by converting a sine wave into a square wave when there is residual magnetism in the motor.

[0051] However, related technologies only consider the angle and frequency of the residual magnetism voltage but not the amplitude of the residual magnetism voltage when the residual magnetism voltage is large. In the case of no residual magnetism working condition, the rotational speed calculation may be incorrect due to a small torque calculation, which may lead to a large restart current impact.

[0052] To solve the technical problem of the restart current impact caused by inaccurate rotational speed calculation in related technologies, this application provides a control method for motor restart, which can reduce the current impact when the motor restarts.

[0053] Refer to Figure 1 , Figure 1 is a schematic flowchart of the first embodiment of a control method for motor restart provided by this application. The method includes:

[0054] Step 110: Obtain the amplitude of the residual magnetism voltage of the motor when it stops.

[0055] Step 120: Determine the rotor frequency of the motor based on the residual magnetism voltage amplitude.

[0056] Step 130: Without changing the rotor frequency, increase the residual magnetism voltage amplitude to the preset frequency converter voltage amplitude in accordance with a preset first step size.

[0057] In some embodiments, the preset first step size may be 1V, 2V, 3V, 4V, 5V, 6V, etc., and can be specifically set according to actual situations, and the present application does not make limitations herein.

[0058] Step 140: Control the motor to start again by using the preset frequency converter voltage amplitude and the rotor frequency.

[0059] In this embodiment, since the residual magnetism voltage amplitude of the motor when it stops is obtained and the residual magnetism voltage amplitude is increased to the preset frequency converter voltage amplitude, that is, the residual magnetism voltage amplitude inside the motor is made to match the output voltage amplitude of the frequency converter (i.e., the preset frequency converter voltage amplitude), current impact caused by voltage difference can be avoided; and without changing the rotor frequency, the residual magnetism voltage amplitude is gradually increased in accordance with the preset first step size, enabling the motor to smoothly transition to the normal operating state, and thus current impact caused by voltage mutation can be effectively avoided.

[0060] In some embodiments, step 110 may include the following step 111 and step 112:

[0061] Step 111: Obtain the phase voltage of the motor.

[0062] Step 112: Obtain the residual magnetism voltage amplitude of the motor when it stops based on the phase voltage.

[0063] Among them, the motor may be a multi-phase motor, such as a three-phase motor.

[0064] Taking a three-phase motor as an example, the specific operations of step 111 and step 112 can refer to the second embodiment of a control method for motor restart provided in the present application, and the method includes:

[0065] Step 210: Obtain the residual magnetism voltage amplitude of the motor when it stops.

[0066] Among them, the motor may be an asynchronous motor.

[0067] Among them, obtaining the residual magnetism voltage amplitude of the motor when it stops in step 210 includes step 211 and step 212:

[0068] Step 211: Obtain the a-phase voltage, b-phase voltage, and c-phase voltage of the motor.

[0069] Step 212: Based on the a-phase voltage, the b-phase voltage, and the c-phase voltage, obtain the residual magnetism voltage amplitude of the motor when it stops.

[0070] Among them, for step 212, the following formula 1 can be specifically adopted:

[0071]

[0072] Among them, U mag is the residual magnetism voltage amplitude, u a is the a-phase voltage, u b is the b-phase voltage, u c is the c-phase voltage.

[0073] Step 220: Based on the residual magnetism voltage amplitude, determine the rotor frequency of the motor.

[0074] In some embodiments, step 220 may include the following steps:

[0075] Step 221: Determine whether the residual magnetism voltage amplitude meets the first preset requirement.

[0076] After calculating the residual magnetism voltage amplitude, the voltage amplitude ratio can be obtained according to the ratio of the residual magnetism voltage amplitude to the rated voltage. Based on this, the first preset requirement can be to determine whether the voltage amplitude ratio is greater than the first preset value.

[0077] Among them, the first preset value can be 5%, 6%, 7%, etc., and can be specifically set according to the actual situation. This application does not make a limitation here.

[0078] Assume that the voltage amplitude ratio is 7% and the first preset value is 5%. Then, the voltage amplitude ratio 7% > the first preset value 5%, and it can be considered that the residual magnetism voltage amplitude meets the first preset requirement.

[0079] If the residual magnetism voltage amplitude meets the first preset requirement, then execute step 222 and step 223.

[0080] Step 222: Based on the a-phase voltage and the b-phase voltage, obtain the phase.

[0081] In some embodiments, step 222 can specifically adopt the following formula 2:

[0082]

[0083] Among them, θ is the phase.

[0084] Step 223: Based on the phase, obtain the rotor frequency of the motor.

[0085] In some embodiments, step 223 can adopt the following formula 3:

[0086]

[0087] Wherein, f is the rotor frequency of the motor, K represents the moment in the discretized difference process, θ(k) represents the phase at the current moment, θ(k - 1) represents the phase at the previous moment, and T s is the discretization period.

[0088] In some embodiments, if the residual magnetism voltage amplitude does not meet the first preset requirement, the stator of the motor is excited until it is determined that the voltage amplitude after excitation meets the first preset requirement, and then return to the above steps 222 and 223 to calculate the rotor frequency.

[0089] Wherein, exciting the stator of the motor until it is determined that the voltage amplitude after excitation meets the first preset requirement may include the following steps 224 to 227.

[0090] Step 224: Gradually increase the voltage of the stator of the motor starting from zero voltage, and determine the current amplitude after excitation.

[0091] Assume that the voltage amplitude ratio is 3%, and the first preset value is 5%. Then, the voltage amplitude ratio 3% < the first preset value 5%, it can be considered that the residual magnetism voltage amplitude does not meet the first preset requirement. Assume that the excitation applied to the motor is 10%, then the voltage amplitude after excitation of the motor is 10%.

[0092] Step 225: When the current amplitude after excitation meets the second preset requirement, the motor is decreased from the default stator frequency to obtain the decreased stator frequency.

[0093] Wherein, the second preset requirement may be that the current amplitude range after excitation is about 30%, and the default stator frequency may be 50 Hz.

[0094] For steps 224 and 225, assume that the residual magnetism voltage amplitude is 3% and the first preset value is 5%. It can be judged that the residual magnetism voltage amplitude 3% is less than the first preset value 5%. Then, the voltage amplitude of the motor is increased from 0 according to the preset second step length. Assume that the total applied excitation voltage amplitude is 10%, then the voltage amplitude after excitation is 10%. Assume that the current amplitude after excitation at this time is 35%, then it can be considered that the second preset requirement is met. Keep the voltage amplitude of 10% after excitation unchanged, and decrease the motor from the default stator frequency.

[0095] Wherein, the preset second step length may be 1V, 2V, 3V, 4V, 5V, 6V, etc., and can be specifically set according to the actual situation. This application does not make a limitation here.

[0096] Step 226: Determine whether the decreased stator frequency satisfies the excitation stop command.

[0097] In some embodiments, step 226 may include the following steps 01-step 03:

[0098] Step 01: Obtain the power change rate of the motor.

[0099] In some embodiments, step 01 of obtaining the power change rate of the motor includes steps 11 and 12:

[0100] Step 11: Obtain the power of the motor and the cut-off frequency of the high-pass filter.

[0101] In some embodiments, obtaining the power of the motor in step 11 includes the following 1)-2):

[0102] 1) Obtain the excitation voltage, excitation current and power factor of the motor.

[0103] 2) Based on the excitation voltage, the excitation current and the power factor, obtain the power of the motor.

[0104] For 1)-2), the following formula 4 can be used:

[0105] P = UIcosφ, formula 4.

[0106] Where, P is the power of the motor; U is the excitation voltage; I is the excitation current, cosφ represents the power factor, and φ represents the phase difference between the voltage and the current.

[0107] For 1)-2), according to the mechanical characteristics of the motor, refer to Figure 2 , when the slip s w of the motor is positive, the power is positive. When the slip s w gradually decreases, the power increases. When the power reaches the peak value and then starts to decrease, when the slip is 0, the power is also 0. During the process of the slip s w gradually decreasing, the distance from the power peak to the slip s w being 0 is very close. Therefore, when it is detected that the power reaches the peak value, that is, when the slip of the asynchronous motor is approximately zero, the excitation is stopped.

[0108] Since the slip s w being 0 means the wave is blocked, the stator frequency fs is close to the rotor frequency fr. Therefore, after the wave is blocked, a relatively large residual magnetism voltage can be excited. That is, when the slip s w is 0, the excitation is stopped, and the amplitude of the voltage after excitation is relatively large.

[0109] Step 12: Based on the power of the motor and the cut-off frequency of the high-pass filter, obtain the power change rate of the motor.

[0110] Among them, step 12 can adopt the following formula 5:

[0111]

[0112] Among them, ΔP is the power change rate of the motor, s is the integral operator, ω c is the cut-off frequency of the high-pass filter, and P is the power of the motor.

[0113] Step 02: Determine whether the power change rate of the motor is zero.

[0114] That is, determine whether ΔP is zero.

[0115] Step 03: If the power change rate of the motor is zero, it is determined that the decreased stator frequency satisfies the field stop command.

[0116] Step 227: If the decreased stator frequency satisfies the field stop command, it is determined that the voltage amplitude after excitation satisfies the first preset requirement, the field excitation operation on the stator of the motor is stopped, and the voltage amplitude after excitation is used as the residual magnet voltage amplitude.

[0117] Step 230: With the rotor frequency unchanged, increase the residual magnet voltage amplitude to the preset inverter voltage amplitude according to a preset first step size.

[0118] In some embodiments, the preset inverter voltage amplitude can be found from a preset voltage-frequency ratio curve, i.e., the V-F curve.

[0119] Among them, the preset voltage-frequency ratio curve can include multiple rotor frequencies during normal operation of the motor and the corresponding voltage amplitudes for each rotor frequency.

[0120] Therefore, according to the preset target rotor frequency, the preset inverter voltage amplitude can be found from the preset voltage-frequency ratio curve.

[0121] Since the calculated voltage and frequency are not proportional when the motor has residual magnet voltage, after obtaining the residual magnet voltage amplitude and rotor frequency of the motor, it is necessary to gradually switch to the normal operating state in the preset voltage-frequency ratio curve. Therefore, keeping the rotor frequency unchanged and gradually increasing the voltage can make the motor switch to the normal operating state.

[0122] That is to say, when the residual magnet voltage amplitude increases to the corresponding preset inverter voltage amplitude in the VF curve, the speed tracking state is exited, and the motor switches to the normal operating state.

[0123] Step 240: Control the motor to start again by using the preset inverter voltage amplitude and the rotor frequency.

[0124] According to the above embodiments, different methods are adopted in this application to calculate the rotor frequency of the motor with or without residual magnetism. When the motor downtime is short and there is still residual magnetism voltage (i.e., the amplitude of the residual magnetism voltage meets the first preset requirement), the rotor frequency and angle are calculated in real time based on the detected motor voltage, and then PWM pulses are generated with the calculated amplitude and phase of the residual magnetism voltage to control the motor, ensuring that the starting current of the motor is smooth and the impact is small; when the motor downtime is long, the back electromotive force of the motor decays to zero (i.e., the amplitude of the residual magnetism voltage does not meet the first preset requirement). Since the motor still has a high rotational speed, in this application, the motor is excited with a varying frequency and a voltage with a fixed amplitude. When the stator frequency of the motor approaches the rotor frequency, the wave is blocked. At this time, the motor can generate a relatively large residual magnetism voltage, and then the amplitude and angle of the residual magnetism voltage are calculated, and PWM pulses are generated with this angle and amplitude to drive the motor to restart. In this way, the rotor frequency of the motor can be accurately determined at different rotational speeds of the motor, ensuring the smoothness of the starting current, thereby reducing the current impact during motor restart.

[0125] Corresponding to the above control method for motor restart, this application also provides a control device for motor restart. The control device for motor restart includes a unit for executing the control method for motor restart in the above embodiments, and the control device for motor restart can be configured in terminals such as desktop computers, tablet computers, laptops, etc.

[0126] As Figure 3 shown, an embodiment of this application provides a computer device, including a processor 111, a communication interface 112, a memory 113, and a communication bus 114. Among them, the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114.

[0127] The memory 113 is used to store computer programs.

[0128] In an embodiment of this application, when the processor 111 executes the program stored on the memory 113, it implements the control method for motor restart provided in any of the foregoing method embodiments, including:

[0129] Obtain the amplitude of the residual magnetism voltage of the motor when it stops.

[0130] Based on the amplitude of the residual magnetism voltage, determine the rotor frequency of the motor.

[0131] Without changing the rotor frequency, increase the amplitude of the residual magnetism voltage to the preset amplitude of the inverter voltage according to a preset first step size.

[0132] Use the preset amplitude of the inverter voltage and the rotor frequency to control the motor to start again.

[0133] Those of ordinary skill in the art can understand that all or part of the processes in the methods of implementing the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a storage medium, and the storage medium is a computer-readable storage medium. The computer program is executed by at least one processor in the computer system to implement the process steps of the embodiments of the above methods.

[0134] Therefore, the embodiments of the present application also provide a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the motor restart control method provided in any of the foregoing method embodiments, including:

[0135] Obtain the residual magnetism voltage amplitude of the motor when it stops;

[0136] Based on the residual magnetism voltage amplitude, determine the rotor frequency of the motor;

[0137] When the rotor frequency remains unchanged, increase the residual magnetism voltage amplitude to the preset frequency converter voltage amplitude in accordance with a preset first step size;

[0138] Use the preset frequency converter voltage amplitude and the rotor frequency to control the motor to start again.

[0139] The storage medium is a physical, non-transitory storage medium, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk, or an optical disc, etc., which are various physical storage media that can store program codes. The computer-readable storage medium can be non-volatile or volatile.

[0140] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0141] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of each unit is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0142] The steps in the method embodiments of the present application can be adjusted, combined, and deleted according to actual needs. The units in the device embodiments of the present application can be combined, divided, and deleted according to actual needs. In addition, in each embodiment of the present application, each functional unit can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0143] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application.

[0144] In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0145] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, provided that these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these changes and modifications.

[0146] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and these modifications or substitutions should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A control method for motor restart, characterized in that, The method includes: Obtaining the residual magnetism voltage amplitude of the motor when it stops; Determining the rotor frequency of the motor based on the residual magnetism voltage amplitude; When the rotor frequency remains unchanged, increasing the residual magnetism voltage amplitude to the preset frequency converter voltage amplitude according to a preset first step length; Using the preset frequency converter voltage amplitude and the rotor frequency to control the motor to start again.

2. The method according to claim 1, wherein The obtaining the residual magnetism voltage amplitude of the motor when it stops includes: Obtaining the phase voltage of the motor; Obtaining the residual magnetism voltage amplitude of the motor when it stops based on the phase voltage.

3. The method according to claim 2, wherein Determining the rotor frequency of the motor based on the residual magnetism voltage amplitude includes: Judging whether the residual magnetism voltage amplitude meets a first preset requirement; If the residual magnetism voltage amplitude meets the first preset requirement, obtaining the residual magnetism voltage amplitude of the motor when it stops based on the phase voltage; If the residual magnetism voltage amplitude does not meet the first preset requirement, exciting the stator of the motor until it is determined that the voltage amplitude after excitation meets the first preset requirement, and then obtaining the residual magnetism voltage amplitude of the motor when it stops based on the phase voltage.

4. The method according to claim 3, wherein The exciting the stator of the motor until it is determined that the voltage amplitude after excitation meets the first preset requirement includes: Gradually increasing the voltage of the stator of the motor from zero voltage and determining the current amplitude after excitation; When the current amplitude after excitation meets a second preset requirement, decreasing the motor from the default stator frequency to obtain the decreased stator frequency; Judging whether the decreased stator frequency meets the excitation stop instruction; If the decreased stator frequency meets the excitation stop instruction, it is determined that the voltage amplitude after excitation meets the first preset requirement, stop the excitation operation of the stator of the motor, and use the voltage amplitude after excitation as the residual magnetism voltage amplitude.

5. The method according to claim 4, characterized in that, The judging whether the decreased stator frequency meets the excitation stop instruction includes: Obtaining the power change rate of the motor; Judging whether the power change rate of the motor is zero; If the power change rate of the motor is zero, it is determined that the decreased stator frequency meets the excitation stop instruction.

6. The method according to claim 5, characterized in that The obtaining the power change rate of the motor includes: Obtaining the power of the motor and the cut-off frequency of the high-pass filter; Obtaining the power change rate of the motor based on the power of the motor and the cut-off frequency of the high-pass filter.

7. The method according to claim 5, wherein The obtaining the power of the motor includes: Obtaining the excitation voltage, excitation current and power factor of the motor; Obtaining the power of the motor based on the excitation voltage, the excitation current and the power factor.

8. A control device for motor restart, characterized in that, It includes a unit for executing the method according to any one of claims 1-7.

9. A computer device, characterized in that, The computer device includes a memory and a processor, a computer program is stored on the memory, and when the processor executes the computer program, the method according to any one of claims 1-7 is implemented.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1-7 can be implemented.

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