Motor speed control method, device, equipment and storage medium

Abstract

The present invention discloses a motor speed control method, device, equipment and computer storage medium, which relate to the field of motor control technology. The method comprises: obtaining the current speed of the motor; comparing the current speed with a first expected speed; if the current speed is lower than the first expected speed, increasing the commutation angle of the motor to obtain a real-time commutation angle; controlling the on-off of a bidirectional thyristor in a motor control system according to the real-time commutation angle, the rotor position of the motor and a zero-crossing signal of a power supply, so that the motor operates at the first expected speed, wherein the first expected speed is greater than the motor speed corresponding to the power supply frequency; the present invention can realize the control of the motor speed by controlling the on-off of the bidirectional thyristor, simplifies the control algorithm of the motor speed control system, and solves the technical problem that the control algorithm of the existing motor speed control system is complex and has high requirements for the controller.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a motor speed control method, device, equipment and storage medium. Background Art

[0002] In related technologies, synchronous motors use an AC-DC-AC control system and an H-bridge drive circuit to invert and output AC signals of various frequencies, thereby controlling the synchronous motors to operate at different speeds. However, the control algorithm in the AC-DC-AC control system is complex and places high demands on the controller, resulting in a high cost for the motor speed control system. Summary of the Invention

[0003] The main purpose of the present invention is to provide a motor speed control method, device, equipment and storage medium, aiming to solve the technical problems of the existing motor speed control system having complex control algorithms and high requirements on the controller.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a method for controlling the speed of a motor, the method comprising:

[0006] Get the current speed of the motor;

[0007] comparing the current rotational speed with a first desired rotational speed;

[0008] If the current speed is lower than the first desired speed, the commutation angle of the motor is increased to obtain a real-time commutation angle;

[0009] According to the real-time commutation angle, the rotor position of the motor and the zero-crossing signal of the power supply, the on-off of the bidirectional thyristor in the motor control system is controlled to make the motor operate at a first desired speed, wherein the first desired speed is greater than the motor speed corresponding to the power supply frequency.

[0010] Optionally, after comparing the current rotational speed with the first expected rotational speed, the method further includes:

[0011] If the current speed is higher than the first expected speed, the commutation angle of the motor is reduced to obtain a real-time commutation angle.

[0012] Optionally, the step of controlling the on and off of a bidirectional thyristor in the motor control system according to the real-time commutation angle, the rotor position of the motor, and the zero-crossing signal of the power supply includes:

[0013] If the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, the bidirectional thyristor is controlled to conduct;

[0014] If the rotor position is not within the real-time commutation angle and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to be turned off.

[0015] Optionally, after comparing the current rotational speed with the first expected rotational speed, the method further includes:

[0016] Get the current conduction angle of the bidirectional thyristor;

[0017] Comparing the current conduction angle with the conduction angle threshold;

[0018] If the current speed is lower than the first desired speed, the commutation angle of the motor is increased to obtain a real-time commutation angle, including:

[0019] If the current conduction angle is equal to the conduction angle threshold, the step of increasing the commutation angle of the motor to obtain a real-time commutation angle is executed if the current rotational speed is lower than the first expected rotational speed.

[0020] Optionally, after comparing the current conduction angle with the conduction angle threshold, the method further includes:

[0021] If the current conduction angle is less than the conduction angle threshold, the current rotational speed is compared with a second desired rotational speed, wherein the second desired rotational speed is less than or equal to the motor rotational speed corresponding to the power supply frequency;

[0022] If the current speed is lower than the second desired speed, the current conduction angle is increased to obtain the desired conduction angle corresponding to the second desired speed;

[0023] The bidirectional thyristor is controlled to conduct at a desired conduction angle, so that the motor operates at a second desired speed.

[0024] Optionally, after the step of comparing the current rotational speed with the second expected rotational speed, the method further comprises:

[0025] If the current rotational speed is higher than the second desired rotational speed, the current conduction angle is reduced to obtain the desired conduction angle corresponding to the second desired rotational speed.

[0026] In a second aspect, the present invention further provides a motor speed control device, comprising:

[0027] Speed ​​acquisition module, used to obtain the current speed of the motor;

[0028] a speed comparison module, configured to compare the current speed with a first expected speed;

[0029] A commutation angle adjustment module is used to increase the commutation angle of the motor to obtain a real-time commutation angle if the current speed is lower than the first expected speed;

[0030] The thyristor control module is used to control the on and off of the bidirectional thyristor in the motor control system according to the real-time commutation angle, the rotor position of the motor and the zero-crossing signal of the power supply, so that the motor operates at a first desired speed, wherein the first desired speed is greater than the motor speed corresponding to the power supply frequency.

[0031] In a third aspect, the present invention also provides a motor speed control device, which includes: a memory, a processor, and a motor speed control program stored in the memory and executable on the processor, and is configured through the motor speed control program to implement the steps of any of the above-mentioned motor speed control methods.

[0032] Optionally, the motor speed control device is a dishwasher.

[0033] In a fourth aspect, the present invention further provides a computer-readable storage medium, on which a motor speed control program is stored. When the motor speed control program is executed by a processor, the steps of any of the above-mentioned motor speed control methods are implemented.

[0034] The present invention provides a motor speed control method, device, equipment and storage medium. When the current speed of the motor is less than the expected speed, the real-time commutation angle is obtained by increasing the commutation angle of the motor. The on-off of a bidirectional thyristor is controlled according to the rotor position of the motor, the real-time commutation angle and the zero-crossing signal of the power supply to control the speed of the motor. By controlling the on-off of the bidirectional thyristor, the motor speed can be controlled, the control algorithm of the motor speed control system is simplified, and the technical problem that the control algorithm of the existing motor speed control system is complex and the controller has high requirements is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0036] Figure 1 It is a structural schematic diagram of the motor speed control device of the present invention;

[0037] Figure 2 1 is a flow chart of a first embodiment of a method for controlling motor speed according to the present invention;

[0038] Figure 3 This is a flow chart of a second embodiment of a motor speed control method according to the present invention;

[0039] Figure 4 1 is a flow chart of a third embodiment of a method for controlling motor speed according to the present invention;

[0040] Figure 5 FIG. 1 is a module diagram of a first embodiment of a motor speed control device according to the present invention.

[0041] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] In the present invention, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a device or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such a device or system. In the absence of further limitations, an element defined by the phrase "comprises..." does not exclude the presence of other identical elements in the device or system comprising the element.

[0045] In view of the technical problems that the existing motor speed control system has complex control algorithms and high requirements for the controller, the present invention provides a motor speed control method. The overall idea is as follows:

[0046] The method includes: obtaining the current speed of the motor; comparing the current speed with a first expected speed; if the current speed is lower than the first expected speed, increasing the commutation angle of the motor to obtain a real-time commutation angle; and controlling the on and off of a bidirectional thyristor in a motor control system according to the real-time commutation angle, the rotor position of the motor, and a zero-crossing signal of a power supply, so that the motor operates at the first expected speed, wherein the first expected speed is greater than the motor speed corresponding to the power supply frequency.

[0047] The present invention provides a motor speed control method. When the current speed of the motor is less than the expected speed, the real-time commutation angle is obtained by increasing the commutation angle of the motor. The on-off of a bidirectional thyristor is controlled according to the rotor position of the motor, the real-time commutation angle and the zero-crossing signal of the power supply to control the speed of the motor. By controlling the on-off of the bidirectional thyristor, the motor speed can be controlled, the control algorithm of the motor speed control system is simplified, and the technical problem that the control algorithm of the existing motor speed control system is complex and the controller has high requirements is solved.

[0048] The motor speed control method, device, equipment and storage medium used in the technical implementation of the present invention are described in detail below:

[0049] Reference Figure 1 , Figure 1 It is a structural schematic diagram of the motor speed control device of the present invention;

[0050] like Figure 1 As shown, the device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a synchronous motor, and the user interface 1003 may optionally include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (Wireless-Fidelity, Wi-Fi) interface). The memory 1005 may be a high-speed random access memory (Random Access Memory, RAM) memory, or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk memory. The memory 1005 may optionally also be a storage device independent of the aforementioned processor 1001.

[0051] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation of the device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0052] like Figure 1 As shown, the memory 1005 as a storage medium may include an operating system, a data storage module, a network communication module, a user interface module and a motor speed control program.

[0053] exist Figure 1 In the device shown, the network interface 1004 is mainly used for data communication with other devices; the user interface 1003 is mainly used for data interaction with user devices; the processor 1001 and the memory 1005 in the motor speed control method of the present invention can be set in the device, and the motor speed control method calls the motor speed control program stored in the memory 1005 through the processor 1001, and executes the motor speed control method provided by the embodiment of the present invention.

[0054] The motor speed control method, device, equipment and storage medium of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Based on the above hardware structure but not limited to the above hardware structure, refer to Figure 2 , Figure 2 This is a flow chart of a first embodiment of a motor speed control method according to the present invention. This embodiment provides a motor speed control method, which includes:

[0056] Step S100: obtaining the current speed of the motor;

[0057] Step S200: comparing the current rotation speed with the first expected rotation speed;

[0058] In this embodiment, the execution subject is a motor control device, which includes a bidirectional thyristor (TRIAC) connected to a power supply and a synchronous motor, and a microcontroller chip connected to the TRIAC. The microcontroller chip stores a motor speed control algorithm. The power supply and the synchronous motor can be turned on or off by controlling the on and off of the TRIAC. The power supply is AC mains electricity, the motor is a synchronous motor, and the TRIAC is composed of two thyristors connected in reverse parallel, including an anode, a cathode, and a control electrode. When a positive voltage is applied to the anode and cathode of the TRIAC and the control electrode, the TRIAC can be controlled to conduct. Once the TRIAC is turned on, the TRIAC remains on even when the control voltage is reduced or removed. When the current between the anode and cathode of the TRIAC is less than the holding current, the TRIAC turns off. The current speed is the speed of the synchronous motor at the current time, and the first desired speed is determined based on actual usage. For example, in this embodiment, the motor speed control device is a dishwasher, and the synchronous motor can be the dishwasher's water pump motor. The first desired speed can be determined based on the water output of the water pump.

[0059] In a specific implementation, the current rotation speed of the dishwasher water pump motor is obtained, and the current rotation speed is compared with the first expected rotation speed.

[0060] Step S300: If the current speed is lower than the first expected speed, the commutation angle of the motor is increased to obtain a real-time commutation angle;

[0061] In this embodiment, one rotation of the motor corresponds to a rotation angle of the motor rotor of 0-360°. When AC power is input to the motor, the upper and lower half waves of the AC power respectively generate two electromagnetic forces, pushing and attracting, on the motor rotor. Usually, if the motor is to keep rotating in one direction, the thrust or suction must be maintained. In the motor control device, the rotation angle of the motor rotor is divided into two sectors, upper and lower. When the motor rotor position is in the upper half sector, if the power supply is in the upper half wave, thrust is generated on the motor rotor and the motor rotates forward. When the motor rotor position is in the lower half sector, if the power supply is in the lower half wave, thrust is still generated on the motor rotor and the motor keeps rotating forward. In this way, the motor realizes It rotates forward; otherwise the motor rotates in the reverse direction; among them, when the upper and lower sectors are switched, the upper and lower half waves of the power supply are required, which is generally called commutation; the corresponding motor rotor position during commutation is called the commutation angle. When the motor speed is less than or equal to the motor speed corresponding to the power supply frequency, the commutation angle is 0° and 180°. When the motor speed is required to be greater than the motor speed corresponding to the power supply frequency, by increasing the commutation angle, the motor rotation angle can exceed 360° within one power supply cycle, so that the motor speed exceeds the motor speed corresponding to the power supply frequency; it should be noted that the motor speed control device includes a Hall sensor, and the commutation angle is related to the installation of the corresponding Hall sensor.

[0062] Step S400: Controlling the on and off of the bidirectional thyristor in the motor control system according to the real-time commutation angle, the rotor position of the motor and the zero-crossing signal of the power supply, so that the motor operates at a first desired speed, wherein the first desired speed is greater than the motor speed corresponding to the power supply frequency.

[0063] In this embodiment, the motor speed control device also includes a zero-crossing detection circuit, which can detect the zero-crossing point of the power supply sinusoidal signal to obtain a zero-crossing signal. Usually, the AC power has two zero-crossing points per cycle. In addition, the rotor position of the motor can be detected by the Hall sensor.

[0064] Specifically, such as Figure 3 As shown, Figure 3 This is a flow chart of a second embodiment of the motor speed control method of the present invention. Step S400 includes:

[0065] Step S410: If the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, the bidirectional thyristor is controlled to be turned on;

[0066] Step S420: If the rotor position is not within the real-time commutation angle and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to be turned off.

[0067] In a specific implementation, if the current speed of the motor is lower than the first expected speed, the commutation angle of the motor is increased to obtain the real-time commutation angle; when the Hall sensor detects that the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, the bidirectional thyristor is controlled to be turned on; when the Hall sensor detects that the rotor position is not within the real-time commutation angle, and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to be turned off.

[0068] This embodiment provides a motor speed control method. When the current speed of the motor is less than the expected speed, the real-time commutation angle is obtained by increasing the commutation angle of the motor. The on-off of the bidirectional thyristor is controlled according to the rotor position of the motor, the real-time commutation angle and the zero-crossing signal of the power supply to control the speed of the motor. By controlling the on-off of the bidirectional thyristor, the motor speed can be controlled, which simplifies the control algorithm of the motor speed control system and solves the technical problem that the control algorithm of the existing motor speed control system is complex and has high requirements for the controller.

[0069] Specifically, such as Figure 3 As shown, Figure 3 This is a flow chart of a second embodiment of a motor speed control method according to the present invention. This embodiment provides a motor speed control method. After step 200, the method further includes:

[0070] Step S500: If the current rotational speed is higher than the first expected rotational speed, the commutation angle of the motor is reduced to obtain a real-time commutation angle.

[0071] In this embodiment, when the current speed of the motor is too high and the motor rotation angle is too large within one power cycle, the motor rotation angle within one power cycle can be reduced by reducing the commutation angle of the motor to reduce the motor speed.

[0072] In a specific implementation, if the current speed of the motor is higher than the first expected speed, the commutation angle of the motor is reduced to obtain the real-time commutation angle; when the Hall sensor detects that the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, the bidirectional thyristor is controlled to be turned on; when the Hall sensor detects that the rotor position is not within the real-time commutation angle, and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to be turned off.

[0073] This embodiment provides a motor speed control method, which reduces the speed of the synchronous motor by controlling the commutation angle, avoids the safety hazards caused by the excessive speed of the synchronous motor, and improves the reliability of the synchronous motor control.

[0074] Specifically, such as Figure 4 As shown, Figure 4 2 is a flow chart of a third embodiment of a motor speed control method according to the present invention. This embodiment provides a motor speed control method. After step S200, the method further includes:

[0075] Step S600: obtaining the current conduction angle of the bidirectional thyristor;

[0076] Step S700: comparing the current conduction angle with the conduction angle threshold;

[0077] Specifically, step S300 includes:

[0078] Step S310: If the current conduction angle is equal to the conduction angle threshold, then if the current rotational speed is lower than the first expected rotational speed, the commutation angle of the motor is increased to obtain a real-time commutation angle.

[0079] In this embodiment, in each power supply cycle, the electrical angle from the power supply zero point to the arrival of the trigger pulse of the bidirectional thyristor control electrode is called the control angle of the bidirectional thyristor, and the electrical angle of conduction in each cycle is called the conduction angle of the bidirectional thyristor. The current conduction angle of the bidirectional thyristor can be obtained through the motor control device. The conduction angle includes 0-100%. When the conduction angle is 0, the synchronous motor does not work. When the conduction angle is 100%, the speed of the synchronous motor is the speed corresponding to the input power frequency; it can be understood that the size of the control angle or conduction angle can characterize the size of the average output voltage of the bidirectional thyristor. The larger the average voltage, the greater the torque and the faster the speed of the synchronous motor; therefore, when the current conduction angle of the bidirectional thyristor is equal to the conduction angle threshold, when the motor speed needs to be greater than the motor speed corresponding to the power supply frequency, by increasing the commutation angle, the motor rotation angle can be made to exceed 360° in one power supply cycle, so that the motor speed exceeds the motor speed corresponding to the power supply frequency.

[0080] In the specific implementation, the current conduction angle of the bidirectional thyristor is obtained to determine whether the current conduction angle is equal to the conduction angle threshold. When the conduction angle is equal to the preset conduction angle threshold, the speed of the synchronous motor is the speed corresponding to the input power frequency. At this time, if you want to increase the speed of the synchronous motor, you can increase the commutation angle of the motor to obtain the real-time commutation angle; when the Hall sensor detects that the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, the bidirectional thyristor is controlled to turn on; when the Hall sensor detects that the rotor position is not within the real-time commutation angle, and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to turn off, so as to increase the motor speed to the first desired speed.

[0081] Specifically, after step S700, the method further includes:

[0082] Step S800: If the current conduction angle is less than the conduction angle threshold, the current rotational speed is compared with a second desired rotational speed, wherein the second desired rotational speed is less than or equal to the motor rotational speed corresponding to the power supply frequency;

[0083] Step S900: if the current rotational speed is lower than the second desired rotational speed, increasing the current conduction angle to obtain the desired conduction angle corresponding to the second desired rotational speed;

[0084] Step S1000: controlling the bidirectional thyristor to conduct at a desired conduction angle, so that the motor operates at a second desired speed.

[0085] In this embodiment, when the current conduction angle of the bidirectional thyristor is less than the conduction angle threshold, the motor commutation angle can be 0° and 180°. By controlling the conduction angle of the bidirectional thyristor, the average output voltage of the bidirectional thyristor can be controlled, and the speed of the synchronous motor can be controlled to change between 0 and the motor speed corresponding to the power supply frequency, that is, the second expected speed is a motor speed between 0 and the motor speed corresponding to the power supply frequency, and the expected conduction angle is 0-100%.

[0086] Specifically, step S900 includes: if the current rotation speed is higher than the second expected rotation speed, reducing the current conduction angle to obtain the expected conduction angle corresponding to the second expected rotation speed.

[0087] In a specific implementation, when the current conduction angle of the bidirectional thyristor is less than the conduction angle threshold, if the current speed is lower than the second expected speed, the current conduction angle is increased to obtain the expected conduction angle corresponding to the second expected speed; or if the current speed is higher than the second expected speed, the current conduction angle is reduced to obtain the expected conduction angle corresponding to the second expected speed; the bidirectional thyristor is controlled to conduct at the expected conduction angle so that the motor operates at the second expected speed.

[0088] This embodiment provides a motor speed control method, which realizes real-time adjustment of the synchronous motor speed by controlling the conduction angle change of a bidirectional thyristor.

[0089] Based on the same inventive concept, the embodiment of the present invention further provides a motor speed control device, referring to Figure 5 , Figure 5 This is a module diagram of a first embodiment of a motor speed control device according to the present invention; the device comprises:

[0090] The speed acquisition module 10 is used to obtain the current speed of the motor;

[0091] A speed comparison module 20 is configured to compare the current speed with a first desired speed;

[0092] a commutation angle adjustment module 30 for increasing the commutation angle of the motor to obtain a real-time commutation angle if the current speed is lower than the first desired speed;

[0093] The thyristor control module 40 is used to control the on and off of the bidirectional thyristor in the motor control system according to the real-time commutation angle, the rotor position of the motor and the zero-crossing signal of the power supply, so that the motor operates at a first desired speed, wherein the first desired speed is greater than the motor speed corresponding to the power supply frequency.

[0094] This embodiment provides a motor speed control device. When the current speed of the motor is less than the expected speed, the real-time commutation angle is obtained by increasing the commutation angle of the motor. The on-off of the bidirectional thyristor is controlled according to the rotor position of the motor, the real-time commutation angle and the zero-crossing signal of the power supply to control the speed of the motor. By controlling the on-off of the bidirectional thyristor, the motor speed can be controlled, which simplifies the control algorithm of the motor speed control system and solves the technical problem that the control algorithm of the existing motor speed control system is complex and has high requirements for the controller.

[0095] For more implementation details of the specific implementation of the above-mentioned motor speed control device, please refer to the description of the specific implementation of the motor speed control method in any one of the above-mentioned embodiments 1 to 3. For the sake of brevity of the description, they will not be repeated here.

[0096] In addition, an embodiment of the present invention further proposes a computer storage medium, on which a motor speed control program is stored, and when the motor speed control program is executed by a processor, the steps of the motor speed control method as described above are implemented. Therefore, no further description will be given here. In addition, the description of the beneficial effects of adopting the same method will not be repeated. For technical details not disclosed in the computer-readable storage medium embodiment involved in this application, please refer to the description of the method embodiment of this application. As an example, the program instructions can be deployed to be executed on one computing device, or on multiple computing devices located at one location, or on multiple computing devices distributed at multiple locations and interconnected by a communication network.

[0097] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The above-described program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The above-described storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0098] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A motor speed control method, characterized in that: The method comprises: Get the current speed of the motor; comparing the current rotational speed with a first desired rotational speed; Get the current conduction angle of the bidirectional thyristor; comparing the current conduction angle with a conduction angle threshold; If the current speed is lower than the first expected speed, increasing the commutation angle of the motor to obtain a real-time commutation angle; Controlling the on / off switching of a bidirectional thyristor in a motor control system according to the real-time commutation angle, the rotor position of the motor, and a zero-crossing signal of a power supply, so that the motor operates at the first desired speed, wherein the first desired speed is greater than a motor speed corresponding to the power supply frequency; If the current speed is lower than the first expected speed, increasing the commutation angle of the motor to obtain a real-time commutation angle includes: If the current conduction angle is equal to the conduction angle threshold, the step of increasing the commutation angle of the motor if the current rotational speed is lower than the first expected rotational speed is executed to obtain a real-time commutation angle.

2. The method according to claim 1, wherein After comparing the current rotational speed with the first expected rotational speed, the method further includes: If the current rotational speed is higher than the first expected rotational speed, the commutation angle of the motor is reduced to obtain the real-time commutation angle.

3. The method according to claim 1, wherein The step of controlling the on and off of a bidirectional thyristor in a motor control system according to the real-time commutation angle, the rotor position of the motor and the zero-crossing signal of the power supply comprises: If the rotor position is within the real-time commutation angle and the zero-crossing signal is a falling edge, controlling the bidirectional thyristor to be turned on; If the rotor position is not within the real-time commutation angle and / or the zero-crossing signal is a rising edge, the bidirectional thyristor is controlled to be turned off.

4. The method according to claim 1, wherein After comparing the current conduction angle with the conduction angle threshold, the method further includes: If the current conduction angle is less than the conduction angle threshold, comparing the current rotational speed with a second expected rotational speed, wherein the second expected rotational speed is less than or equal to the motor rotational speed corresponding to the power supply frequency; If the current speed is lower than the second desired speed, increasing the current conduction angle to obtain the desired conduction angle corresponding to the second desired speed; The bidirectional thyristor is controlled to conduct at the desired conduction angle, so that the motor operates at the second desired speed.

5. The method according to claim 4, wherein After the step of comparing the current rotational speed with the second desired rotational speed, the method further includes: If the current rotational speed is higher than the second expected rotational speed, the current conduction angle is reduced to obtain an expected conduction angle corresponding to the second expected rotational speed.

6. A motor speed control device, characterized in that: The device comprises: Speed ​​acquisition module, used to obtain the current speed of the motor; A speed comparison module is used to compare the current speed with a first expected speed; the speed comparison module is also used to obtain a current conduction angle of the bidirectional thyristor; and compare the current conduction angle with a conduction angle threshold; a commutation angle adjustment module, configured to increase the commutation angle of the motor to obtain a real-time commutation angle if the current speed is lower than the first expected speed, and further configured to increase the commutation angle of the motor to obtain a real-time commutation angle if the current conduction angle is equal to the conduction angle threshold; A thyristor control module is used to control the on and off of a bidirectional thyristor in a motor control system according to the real-time commutation angle, the rotor position of the motor, and the zero-crossing signal of the power supply, so that the motor operates at the first desired speed, wherein the first desired speed is greater than the motor speed corresponding to the power supply frequency.

7. A motor speed control device, characterized in that: The device includes: a memory, a processor, and a motor speed control program stored in the memory and executable on the processor. The motor speed control program is configured to implement the steps of the motor speed control method according to any one of claims 1 to 5.

8. The device according to claim 7, characterized in that The motor speed control device is a dishwasher.

9. A computer-readable storage medium, characterized in that The storage medium stores a motor speed control program, which, when executed by the processor, implements the steps of the motor speed control method according to any one of claims 1 to 5.

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