Spindle motor control method, system, device and storage medium for CNC machine tools

Abstract

The present invention discloses a spindle motor control method, system, device and storage medium for a numerically controlled machine tool, the method comprising: when detecting that a frequency converter is started, controlling the spindle motor in accordance with an FVC mode; collecting a first measured speed of the spindle motor through an encoder, and obtaining a first estimated speed and a first estimated magnetic field position of the spindle motor through an SVC estimation module; when the mean between the first estimated speed and the first measured speed is greater than an upper threshold value; controlling the spindle motor in accordance with the first estimated speed and the first estimated magnetic field position in accordance with an SVC mode. When the estimated speed of the spindle motor obtained by the SVC estimation module is greater than the upper threshold value, the present invention switches the FVC mode to the SVC mode, and controls the spindle motor in accordance with the estimated speed and the estimated magnetic field position in accordance with the SVC mode, thereby avoiding the problem of motor loss of control caused by failure of magnetic field position detection due to belt slippage in FVC control.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a spindle motor control method, system, device and storage medium for a numerically controlled machine tool. Background Art

[0002] CNC machine tools are increasingly widely used in industrial production. The main transmission system of CNC machine tools includes spindle motors, transmission systems and spindle components. Compared with the main transmission system of ordinary machine tools, the structure is relatively simple, because all or most of the speed change functions are undertaken by the stepless speed regulation of the spindle motor. Multi-purpose and versatile CNC machine tools require a wide speed regulation range for the spindle motor, requiring not only low speed and high torque, but also high speed, so the selection and control of the spindle motor are particularly important. Some CNC machine tools have requirements for spindle position control, such as directional accurate stop. The transmission system is a flexible connection. When the speed is very high, there is a situation of belt slippage. At this time, the speed of the spindle motor and the speed of the spindle are not unified. The speed of the spindle motor is greater than the speed of the spindle, and it may even be much greater. The encoder detects the information of the spindle. If the spindle motor is closed-loop vector controlled (FVC) according to the information detected by the encoder at this time, the speed and magnetic field position will undoubtedly be wrong, which will lead to the motor out of control. Therefore, how to avoid FVC control out of control has become an urgent problem to be solved.

[0003] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The main purpose of the present invention is to provide a spindle motor control method, system, device and storage medium for a CNC machine tool, aiming to solve the technical problem of how to avoid FVC control out of control.

[0005] To achieve the above object, the present invention provides a spindle motor control method for a CNC machine tool, wherein the spindle platform comprises a machine tool spindle and a spindle motor, and an encoder is installed on the machine tool spindle;

[0006] The spindle motor control method of the CNC machine tool comprises the following steps:

[0007] When the inverter is detected to be started, the spindle motor is controlled according to the FVC mode;

[0008] Acquire a first measured rotation speed of the spindle motor through an encoder, and obtain a first estimated rotation speed and a first estimated magnetic field position of the spindle motor through an SVC estimation module;

[0009] When the average of the first estimated speed and the first measured speed is greater than an upper threshold, switching the FVC mode to the SVC mode;

[0010] The spindle motor is controlled by the SVC method according to the first estimated rotation speed and the first estimated magnetic field position.

[0011] Optionally, before the step of switching the FVC mode to the SVC mode when the average of the first estimated speed and the first measured speed is greater than an upper limit threshold, the step further includes:

[0012] determining whether a speed difference between the first measured speed and the first estimated speed is less than a preset speed difference threshold;

[0013] If so, it is determined whether the first estimated rotation speed is greater than an upper limit threshold.

[0014] Optionally, when the average of the first estimated speed and the first measured speed is greater than an upper limit threshold, the step of switching the FVC mode to the SVC mode includes:

[0015] When the average of the first estimated rotation speed and the first measured rotation speed is greater than an upper limit threshold, determining an angle difference between a first measured magnetic field position of the spindle motor acquired by the encoder and the first estimated magnetic field position;

[0016] Determine whether the angle difference is greater than a preset angle threshold;

[0017] If so, it is determined that the belt is slipping, and the FVC mode is switched to the SVC mode.

[0018] Optionally, after the step of determining whether the angle difference is greater than a preset angle threshold, the method further includes:

[0019] When the angle difference is less than or equal to the preset angle threshold, it is determined that the belt does not slip.

[0020] Optionally, after the step of controlling the spindle motor in the SVC manner according to the first estimated rotation speed and the first estimated magnetic field position, the method further includes:

[0021] Acquire a second measured rotation speed and a second measured magnetic field position of the spindle motor by the encoder, and acquire a second estimated rotation speed of the spindle motor by the SVC estimation module;

[0022] determining whether a speed difference between the second measured speed and the second estimated speed is less than a preset speed difference threshold;

[0023] If yes, when the second estimated speed is less than a lower threshold, switching the SVC mode to the FVC mode;

[0024] The spindle motor is controlled by the FVC method according to the second measured rotation speed and the second measured magnetic field position.

[0025] In addition, to achieve the above-mentioned purpose, the present invention also proposes a spindle motor control system for a CNC machine tool, wherein the spindle platform comprises a machine tool spindle and a spindle motor, and an encoder is installed on the machine tool spindle;

[0026] The spindle motor control system of the CNC machine tool comprises:

[0027] A startup module, used for controlling the spindle motor in accordance with the FVC mode when detecting that the frequency converter is started;

[0028] an acquisition module, configured to acquire a first measured rotation speed of the spindle motor through an encoder, and acquire a first estimated rotation speed and a first estimated magnetic field position of the spindle motor through an SVC estimation module;

[0029] a switching module, configured to switch the FVC mode to the SVC mode when the average of the first estimated rotation speed and the first measured rotation speed is greater than an upper threshold;

[0030] A control module is used to control the spindle motor through the SVC method according to the first estimated rotation speed and the first estimated magnetic field position.

[0031] In addition, to achieve the above-mentioned purpose, the present invention also proposes a spindle motor control device for a CNC machine tool, the device comprising: a memory, a processor, and a spindle motor control program for a CNC machine tool stored in the memory and executable on the processor, the spindle motor control program for the CNC machine tool being configured to implement the steps of the spindle motor control method for a CNC machine tool as described above.

[0032] In addition, to achieve the above-mentioned purpose, the present invention also proposes a storage medium, on which a spindle motor control program for a CNC machine tool is stored. When the spindle motor control program for the CNC machine tool is executed by a processor, the steps of the spindle motor control method for the CNC machine tool as described above are implemented.

[0033] The spindle platform of the present invention comprises a machine tool spindle and a spindle motor, and an encoder is installed on the machine tool spindle. When the frequency converter is detected to be started, the spindle motor is first controlled according to the FVC mode, and then the first measured speed of the spindle motor is collected by the encoder, and the first estimated speed and the first estimated magnetic field position of the spindle motor are obtained by the SVC estimation module. When the mean value between the first estimated speed and the first measured speed is greater than the upper limit threshold, the FVC mode is switched to the SVC mode, and then the spindle motor is controlled by the SVC mode according to the first estimated speed and the first estimated magnetic field position. Compared with the prior art in which the spindle motor is controlled by the FVC mode according to the information detected by the encoder, there is no doubt that the speed and the magnetic field position will be wrong, resulting in the motor being out of control. When the mean value between the estimated speed of the spindle motor and the first measured speed obtained by the SVC estimation module is greater than the upper limit threshold, the present invention switches the FVC mode to the SVC mode, and controls the spindle motor by the SVC mode according to the estimated speed and the estimated magnetic field position, thereby avoiding the problem of FVC control out of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a spindle motor control device for a CNC machine tool in a hardware operating environment involved in an embodiment of the present invention;

[0035] Figure 2 It is a flow chart of a first embodiment of a method for controlling a spindle motor of a CNC machine tool according to the present invention;

[0036] Figure 3 A system block diagram of a first embodiment of a spindle motor control method for a CNC machine tool according to the present invention;

[0037] Figure 4 It is a FVC control block diagram of a spindle motor of a CNC machine tool according to a first embodiment of a spindle motor control method of a CNC machine tool of the present invention;

[0038] Figure 5 It is a control block diagram of the SVC of the spindle motor of a CNC machine tool according to the first embodiment of the spindle motor control method of the CNC machine tool of the present invention;

[0039] Figure 6 The FVC and SVC switching conditions of the first embodiment of the spindle motor control method for a CNC machine tool of the present invention adopt a hysteresis loop structure diagram;

[0040] Figure 7 It is a structural block diagram of the first embodiment of the spindle motor control system of a CNC machine tool of the present invention.

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

[0042] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0043] Reference Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of a spindle motor control device for a CNC machine tool in the hardware operating environment involved in the embodiment of the present invention.

[0044] like Figure 1 As shown, the spindle motor control device of the CNC machine tool 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 display screen (DisPlay), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also 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), or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk storage. The memory 1005 may also be a storage system independent of the aforementioned processor 1001.

[0045] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the spindle motor control device of the numerically controlled machine tool, and may include more or less components than those shown in the figure, or combine certain components, or arrange the components differently.

[0046] like Figure 1 As shown, the memory 1005 as a storage medium may include an operating system, a network communication module, a user interface module, and a spindle motor control program for a numerically controlled machine tool.

[0047] exist Figure 1In the spindle motor control device of the CNC machine tool shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the spindle motor control device of the CNC machine tool of the present invention can be set in the spindle motor control device of the CNC machine tool, and the spindle motor control device of the CNC machine tool calls the spindle motor control program of the CNC machine tool stored in the memory 1005 through the processor 1001, and executes the spindle motor control method of the CNC machine tool provided in the embodiment of the present invention.

[0048] The embodiment of the present invention provides a spindle motor control method for a CNC machine tool, referring to Figure 2 , Figure 2 It is a flow chart of the first embodiment of the spindle motor control method of a CNC machine tool according to the present invention.

[0049] In this embodiment, reference Figure 3 , Figure 3 The system block diagram of the first embodiment of the spindle motor control method of the CNC machine tool of the present invention is composed of an encoder detection module, a spindle platform, a transmission belt, a spindle motor, a frequency converter and a power supply. The encoder detection module is used to detect the position and speed of the spindle motor; the spindle platform is used for processing CNC machine tool products; the transmission belt connects the spindle motor and the spindle, and the rotation of the spindle motor drives the belt to rotate and then drives the spindle to rotate; the power supply supplies power to the frequency converter, and the frequency converter controls the spindle motor. The usual control method is FVC or open-loop vector control (SVC); FVC control has a wide speed regulation range due to the presence of the encoder, and has excellent performance at both low and high speeds. However, in the system involved in the present invention, the encoder is not installed on the motor shaft, but on the spindle after the belt transmission stage.

[0050] It should also be noted that the spindle platform includes a machine tool spindle and a spindle motor. The encoder is installed on the machine tool spindle. The spindle motor drives the machine tool spindle to rotate. The spindle platform is the power system of the CNC machine tool. The rotation of the spindle motor drives the machine tool spindle to move, so that the spindle platform starts working and performing production tasks.

[0051] The spindle motor control method of the CNC machine tool comprises the following steps:

[0052] Step S10: When it is detected that the frequency converter is started, the spindle motor is controlled in accordance with the FVC mode.

[0053] It is easy to understand that the execution subject of this embodiment can be a spindle motor control system of a CNC machine tool with functions such as data processing, network communication and program running, or other computer equipment with similar functions, etc., and this embodiment is not limited.

[0054] It should also be understood that the frequency converter is in operation. When the frequency converter is started, the spindle motor is first controlled in accordance with the FVC method according to the speed and magnetic field position detected by the encoder. Figure 4 , Figure 4 This is a FVC control block diagram of a spindle motor of a CNC machine tool according to a first embodiment of a spindle motor control method for a CNC machine tool of the present invention.

[0055] The FVC method is adopted to realize the startup and medium and low speed control of the spindle motor. At this time, the algorithm of the SVC estimation module is also executed normally, but the speed and magnetic field position estimated by the SVC estimation module are not used for control.

[0056] Step S20: acquiring a first measured rotation speed of the spindle motor through an encoder, and acquiring a first estimated rotation speed and a first estimated magnetic field position of the spindle motor through an SVC estimation module.

[0057] It should also be noted that the first measured rotation speed and the first measured magnetic field position of the spindle motor are collected in real time by the encoder, and the first estimated rotation speed and the first estimated magnetic field position of the spindle motor are acquired in real time by the SVC estimation module at the same time as the encoder.

[0058] It should be understood that if there is no error in the algorithm in the SVC estimation module, the first measured speed is similar to the first estimated speed.

[0059] Further, it is determined whether the speed difference between the first measured speed and the first estimated speed is less than a preset speed difference threshold. If so, it is proved that the algorithm estimation in the SVC estimation module is correct, and it is determined whether the first estimated speed is greater than an upper limit threshold.

[0060] The preset speed difference threshold is customized by the user according to the actual scenario, and can be 1% of the first measured speed, or 2% of the first measured speed, etc., which is not limited in this embodiment.

[0061] The upper limit threshold can be customized by the user according to the actual scenario, which can be 1000 rpm, 1500 rpm, etc.

[0062] Step S30: When the average value between the first estimated rotational speed and the first measured rotational speed is greater than an upper threshold, switching the FVC mode to the SVC mode.

[0063] Further, when the average value between the first estimated rotational speed and the first measured rotational speed is greater than the upper limit threshold, or the first estimated rotational speed is greater than the upper limit threshold, determine the angle difference between the first measured magnetic field position of the spindle motor collected by the encoder and the first estimated magnetic field position; judge whether the angle difference is greater than a preset angle threshold; if so, determine that the belt is slipping, and switch the FVC mode to the SVC mode; when the angle difference is less than or equal to the preset angle threshold, determine that the belt is not slipping.

[0064] The preset angle threshold may be a user-defined setting, and may be 45 degrees, or 40 degrees, etc., and this embodiment does not limit this.

[0065] Step S40: controlling the spindle motor through the SVC method according to the first estimated rotation speed and the first estimated magnetic field position.

[0066] In this embodiment, when it is detected that the average value between the first estimated rotation speed and the first measured rotation speed is greater than the upper limit threshold, it is necessary to switch the FVC mode to the SVC mode.

[0067] In the specific implementation, the speed and magnetic field position estimated by SVC replace the speed and magnetic field position calculated by encoder detection. In this way, when the speed continues to increase, the SVC method is adopted. Even if the belt slips, the SVC method still estimates the correct motor speed and position. Then, the spindle motor is controlled by the SVC method according to the first estimated speed and the first estimated magnetic field position. Figure 5 , Figure 5 This is a control block diagram of the SVC of a spindle motor of a CNC machine tool according to the first embodiment of the spindle motor control method of the CNC machine tool of the present invention.

[0068] Furthermore, after the spindle motor is controlled by the SVC mode according to the first estimated rotational speed and the first estimated magnetic field position, the second measured rotational speed and the second measured magnetic field position of the spindle motor are collected by the encoder, and the second estimated rotational speed of the spindle motor is obtained by the SVC estimation module; it is determined whether the rotational speed difference between the second measured rotational speed and the second estimated rotational speed is less than a preset rotational speed difference threshold; if so, when the second estimated rotational speed is less than a lower limit threshold, or the average value between the second estimated rotational speed and the second measured rotational speed is less than the lower limit threshold, the SVC mode is switched to the FVC mode; and the spindle motor is controlled by the FVC mode according to the second measured rotational speed and the second measured magnetic field position.

[0069] refer to Figure 6 , Figure 6The switching conditions of FVC and SVC of the first embodiment of the spindle motor control method of the CNC machine tool of the present invention adopt a hysteresis structure diagram. In order to ensure the rapidity of the switching between the FVC and SVC modes, instantaneous switching is adopted, that is, the speed and magnetic field position do not adopt a strategy such as ramp transition during switching, but directly replace the value of one mode with the value of another mode. This is because the motor speed is already relatively high when switching, and the speed and magnetic field position estimated by SVC can be very accurate, that is, the value estimated by SVC is very close to the speed and magnetic field position detected by the encoder, so it can be switched directly. In order to ensure the stability of the switching between the FVC and SVC modes, the judgment condition of the switching adopts a speed hysteresis, and the upper and lower thresholds of the switching are set to ensure that the switching condition will not be repeatedly triggered near the switching point.

[0070] It should also be understood that the lower threshold can be a user-defined value of 500 rpm, etc., and the upper threshold needs to have a difference with the lower threshold and cannot be the same. If the upper threshold is consistent with the lower threshold, the detected speed will fluctuate, and the FVC mode and the SVC mode will switch back and forth, resulting in instability. Therefore, the upper threshold needs to be greater than the lower threshold, and there is a difference between the upper threshold and the lower threshold (i.e., a hysteresis strategy). A hysteresis strategy is adopted between the two thresholds to prevent repeated triggering of switching conditions near the switching point.

[0071] In the specific implementation, when the frequency converter controls the spindle motor to decelerate and stop from high speed, the spindle motor just starts to run in high-speed SVC mode. As the speed decreases, when the speed reaches the set switching lower limit threshold, the motor speed and magnetic field position calculated by the encoder detection replace the speed and magnetic field position estimated by the SVC, so that it switches to the FVC mode, which can ensure the performance of medium and low speeds and meet certain position control requirements (such as directional accurate stop function).

[0072] In this embodiment, the spindle platform includes a machine tool spindle and a spindle motor, and the encoder is installed on the machine tool spindle. When the inverter is detected to be started, the spindle motor is first controlled according to the FVC mode, and then the first measured speed of the spindle motor is collected by the encoder, and the first estimated speed and the first estimated magnetic field position of the spindle motor are obtained by the SVC estimation module. When the average value between the first estimated speed and the first measured speed is greater than the upper limit threshold, the FVC mode is switched to the SVC mode, and then the spindle motor is controlled by the SVC mode according to the first estimated speed and the first estimated magnetic field position. Compared with the prior art in which the spindle motor is controlled by the FVC mode according to the information detected by the encoder, there is no doubt that the speed and the magnetic field position will be wrong, resulting in the motor being out of control. In this embodiment, when the estimated speed of the spindle motor obtained by the SVC estimation module is greater than the upper limit threshold, the FVC mode is switched to the SVC mode, and the spindle motor is controlled by the SVC mode according to the estimated speed and the estimated magnetic field position, thereby avoiding the problem of FVC control out of control.

[0073] Reference Figure 7 , Figure 7 It is a structural block diagram of the first embodiment of the spindle motor control system of a CNC machine tool of the present invention.

[0074] like Figure 7 As shown, the spindle platform includes a machine tool spindle and a spindle motor, an encoder is installed on the machine tool spindle, and the spindle motor control system of the CNC machine tool proposed in the embodiment of the present invention includes:

[0075] In this embodiment, reference Figure 3 , Figure 3 The system block diagram of the first embodiment of the spindle motor control method of the CNC machine tool of the present invention is composed of an encoder detection module, a spindle platform, a transmission belt, a spindle motor, a frequency converter and a power supply. The encoder detection module is used to detect the position and speed of the spindle motor; the spindle platform is used for processing CNC machine tool products; the transmission belt connects the spindle motor and the spindle, and the rotation of the spindle motor drives the belt to rotate and then drives the spindle to rotate; the power supply supplies power to the frequency converter, and the frequency converter controls the spindle motor. The usual control method is FVC or open-loop vector control (SVC); FVC control has a wide speed regulation range due to the presence of the encoder, and has excellent performance at both low and high speeds. However, in the system involved in the present invention, the encoder is not installed on the motor shaft, but on the spindle after the belt transmission stage.

[0076] It should also be noted that the spindle platform includes a machine tool spindle and a spindle motor. The encoder is installed on the machine tool spindle. The spindle motor drives the machine tool spindle to rotate. The spindle platform is the power system of the CNC machine tool. The rotation of the spindle motor drives the machine tool spindle to move, so that the spindle platform starts working and performing production tasks.

[0077] The startup module 7001 is used to control the spindle motor in accordance with the FVC mode when detecting that the frequency converter is started.

[0078] It should also be understood that the frequency converter is in operation. When the frequency converter is started, the spindle motor is first controlled in accordance with the FVC method according to the speed and magnetic field position detected by the encoder. Figure 4 , Figure 4 This is a FVC control block diagram of a spindle motor of a CNC machine tool according to a first embodiment of a spindle motor control method for a CNC machine tool of the present invention.

[0079] The FVC method is adopted to realize the startup and medium and low speed control of the spindle motor. At this time, the algorithm of the SVC estimation module is also executed normally, but the speed and magnetic field position estimated by the SVC estimation module are not used for control.

[0080] The acquisition module 7002 is used to collect the first measured rotation speed of the spindle motor through an encoder, and acquire the first estimated rotation speed and the first estimated magnetic field position of the spindle motor through an SVC estimation module.

[0081] It should also be noted that the first measured rotation speed and the first measured magnetic field position of the spindle motor are collected in real time by the encoder, and the first estimated rotation speed and the first estimated magnetic field position of the spindle motor are acquired in real time by the SVC estimation module at the same time as the encoder.

[0082] It should be understood that if there is no error in the algorithm in the SVC estimation module, the first measured speed is similar to the first estimated speed.

[0083] Further, it is determined whether the speed difference between the first measured speed and the first estimated speed is less than a preset speed difference threshold. If so, it is proved that the algorithm estimation in the SVC estimation module is correct, and it is determined whether the first estimated speed is greater than an upper limit threshold.

[0084] The preset speed difference threshold is customized by the user according to the actual scenario, and can be 1% of the first measured speed, or 2% of the first measured speed, etc., which is not limited in this embodiment.

[0085] The upper limit threshold can be customized by the user according to the actual scenario, which can be 1000 rpm, 1500 rpm, etc.

[0086] The switching module 7003 is used to switch the FVC mode to the SVC mode when the first estimated rotation speed is greater than an upper limit threshold.

[0087] Further, when the first estimated rotational speed is greater than the upper limit threshold, the angle difference between the first measured magnetic field position of the spindle motor collected by the encoder and the first estimated magnetic field position is determined; whether the angle difference is greater than a preset angle threshold is judged; if so, it is determined that the belt is slipping, and the FVC mode is switched to the SVC mode; when the angle difference is less than or equal to the preset angle threshold, it is determined that the belt is not slipping.

[0088] The preset angle threshold may be a user-defined setting, and may be 45 degrees, or 40 degrees, etc., and this embodiment does not limit this.

[0089] The control module 7004 is used to control the spindle motor through the SVC method according to the first estimated rotation speed and the first estimated magnetic field position.

[0090] In this embodiment, when it is detected that the first estimated rotation speed is greater than the upper limit threshold, it is necessary to switch the FVC mode to the SVC mode.

[0091] In the specific implementation, the speed and magnetic field position estimated by SVC replace the speed and magnetic field position calculated by encoder detection. In this way, when the speed continues to increase, the SVC method is adopted. Even if the belt slips, the SVC method still estimates the correct motor speed and position. Then, the spindle motor is controlled by the SVC method according to the first estimated speed and the first estimated magnetic field position. Figure 5 , Figure 5 This is a control block diagram of the SVC of a spindle motor of a CNC machine tool according to the first embodiment of the spindle motor control method of the CNC machine tool of the present invention.

[0092] Furthermore, after the spindle motor is controlled by the SVC mode according to the first estimated rotational speed and the first estimated magnetic field position, the second measured rotational speed and the second measured magnetic field position of the spindle motor are collected by the encoder, and the second estimated rotational speed of the spindle motor is obtained by the SVC estimation module; it is determined whether the rotational speed difference between the second measured rotational speed and the second estimated rotational speed is less than a preset rotational speed difference threshold; if so, when the second estimated rotational speed is less than a lower limit threshold, the SVC mode is switched to the FVC mode; and the spindle motor is controlled by the FVC mode according to the second measured rotational speed and the second measured magnetic field position.

[0093] refer to Figure 6 , Figure 6The switching conditions of FVC and SVC of the first embodiment of the spindle motor control method of the CNC machine tool of the present invention adopt a hysteresis structure diagram. In order to ensure the rapidity of the switching between the FVC and SVC modes, instantaneous switching is adopted, that is, the speed and magnetic field position do not adopt a strategy such as ramp transition during switching, but directly replace the value of one mode with the value of another mode. This is because the motor speed is already relatively high when switching, and the speed and magnetic field position estimated by SVC can be very accurate, that is, the value estimated by SVC is very close to the speed and magnetic field position detected by the encoder, so it can be switched directly. In order to ensure the stability of the switching between the FVC and SVC modes, the judgment condition of the switching adopts a speed hysteresis, and the upper and lower thresholds of the switching are set to ensure that the switching condition will not be repeatedly triggered near the switching point.

[0094] It should also be understood that the lower threshold can be a user-defined value of 500 rpm, etc., and the upper threshold needs to have a difference with the lower threshold and cannot be the same. If the upper threshold is consistent with the lower threshold, the detected speed will fluctuate, and the FVC mode and the SVC mode will switch back and forth, resulting in instability. Therefore, the upper threshold needs to be greater than the lower threshold, and there is a difference between the upper threshold and the lower threshold (i.e., a hysteresis strategy). A hysteresis strategy is adopted between the two thresholds to prevent repeated triggering of switching conditions near the switching point.

[0095] In the specific implementation, when the frequency converter controls the spindle motor to decelerate and stop from high speed, the spindle motor just starts to run in high-speed SVC mode. As the speed decreases, when the speed reaches the set switching lower limit threshold, the motor speed and magnetic field position calculated by the encoder detection replace the speed and magnetic field position estimated by the SVC, so that it switches to the FVC mode, which can ensure the performance of medium and low speeds and meet certain position control requirements (such as directional accurate stop function).

[0096] In this embodiment, the spindle platform includes a machine tool spindle and a spindle motor, and the encoder is installed on the machine tool spindle. When the frequency converter is detected to be started, the spindle motor is first controlled according to the FVC mode, and then the first measured speed of the spindle motor is collected through the encoder, and the first estimated speed and the first estimated magnetic field position of the spindle motor are obtained through the SVC estimation module. When the first estimated speed is greater than the upper limit threshold, the FVC mode is switched to the SVC mode, and then the spindle motor is controlled by the SVC mode according to the first estimated speed and the first estimated magnetic field position. Compared with the prior art in which the spindle motor is controlled by the FVC mode according to the information detected by the encoder, there is no doubt that the speed and the magnetic field position will be wrong, resulting in the motor being out of control. In this embodiment, when the estimated speed of the spindle motor obtained by the SVC estimation module is greater than the upper limit threshold, the FVC mode is switched to the SVC mode, and the spindle motor is controlled by the SVC mode according to the estimated speed and the estimated magnetic field position, thereby avoiding the problem of FVC control out of control.

[0097] Other embodiments or specific implementations of the spindle motor control system of the CNC machine tool of the present invention can refer to the above-mentioned method embodiments, which will not be described in detail here.

[0098] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0099] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0100] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0101] 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 specification 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 spindle motor control method for a CNC machine tool, characterized in that: The spindle platform includes a machine tool spindle and a spindle motor, and an encoder is installed on the machine tool spindle; The spindle motor control method of the CNC machine tool comprises the following steps: When the inverter is detected to be started, the spindle motor is controlled according to a closed-loop vector control FVC mode; Acquire a first measured rotation speed of the spindle motor through an encoder, and obtain a first estimated rotation speed and a first estimated magnetic field position of the spindle motor through an open-loop vector control SVC estimation module; When the average value between the first estimated speed and the first measured speed is greater than an upper threshold, switching the closed-loop vector control FVC mode to an open-loop vector control SVC mode; Controlling the spindle motor by the open-loop vector control (SVC) method according to the first estimated rotation speed and the first estimated magnetic field position; Wherein, when the average value between the first estimated speed and the first measured speed is greater than an upper limit threshold, the step of switching the closed-loop vector control FVC mode to the open-loop vector control SVC mode includes: When the average of the first estimated rotation speed and the first measured rotation speed is greater than an upper limit threshold, determining an angle difference between a first measured magnetic field position of the spindle motor acquired by the encoder and the first estimated magnetic field position; Determine whether the angle difference is greater than a preset angle threshold; If yes, it is determined that the belt is slipping, and the closed-loop vector control FVC mode is switched to an open-loop vector control SVC mode; When the angle difference is less than or equal to the preset angle threshold, it is determined that the belt does not slip.

2. The method according to claim 1, characterized in that Before the step of switching the closed-loop vector control FVC mode to the open-loop vector control SVC mode when the average value between the first estimated speed and the first measured speed is greater than an upper limit threshold, the method further includes: determining whether a speed difference between the first measured speed and the first estimated speed is less than a preset speed difference threshold; If so, it is determined whether the average of the first estimated rotational speed and the first measured rotational speed is greater than an upper threshold.

3. The method according to claim 1, characterized in that After the step of controlling the spindle motor by the open-loop vector control SVC method according to the first estimated rotation speed and the first estimated magnetic field position, the method further includes: Acquiring a second measured rotation speed and a second measured magnetic field position of the spindle motor by means of the encoder, and acquiring a second estimated rotation speed of the spindle motor by means of the open-loop vector control SVC estimation module; determining whether a speed difference between the second measured speed and the second estimated speed is less than a preset speed difference threshold; If yes, when the second estimated speed is less than a lower limit threshold, the open-loop vector control SVC mode is switched to the closed-loop vector control FVC mode; The spindle motor is controlled by the closed-loop vector control (FVC) method according to the second measured rotation speed and the second measured magnetic field position.

4. A spindle motor control system for a CNC machine tool, characterized in that: The spindle platform includes a machine tool spindle and a spindle motor, and an encoder is installed on the machine tool spindle; The spindle motor control system of the CNC machine tool comprises: A starting module, used to control the spindle motor in a closed-loop vector control FVC manner when detecting that the frequency converter is started; An acquisition module, used for acquiring a first measured rotation speed of the spindle motor through an encoder, and acquiring a first estimated rotation speed and a first estimated magnetic field position of the spindle motor through an open-loop vector control SVC estimation module; A switching module, configured to switch the closed-loop vector control FVC mode to an open-loop vector control SVC mode when the average value between the first estimated speed and the first measured speed is greater than an upper threshold value; a control module, configured to control the spindle motor through the open-loop vector control (SVC) method according to the first estimated rotation speed and the first estimated magnetic field position; The spindle motor control system of the CNC machine tool is a step of implementing the spindle motor control method of the CNC machine tool according to any one of claims 1 to 3.

5. A spindle motor control device for a CNC machine tool, characterized in that: The device comprises: a memory, a processor, and a spindle motor control program for a CNC machine tool stored in the memory and executable on the processor, wherein the spindle motor control program for the CNC machine tool is configured to implement the steps of the spindle motor control method for a CNC machine tool as claimed in any one of claims 1 to 3.

6. A storage medium, characterized in that: The storage medium stores a spindle motor control program for a CNC machine tool, and when the spindle motor control program for a CNC machine tool is executed by a processor, the steps of the spindle motor control method for a CNC machine tool according to any one of claims 1 to 3 are implemented.

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