Permanent magnet synchronous motor initial position calibration method based on magnetic encoder

Abstract

The application discloses a kind of permanent magnet synchronous motor initial position calibration methods based on magnetic encoder, including whether the motor phase sequence is correct according to motor electric angle given value variation and the mechanical angle variation of magnetic encoder feedback;After determining that the motor phase sequence is correct, the given motor electric angle, the mechanical angle of magnetic encoder feedback, the motor electric angle variation and the mechanical angle variation of magnetic encoder feedback in the rotation of motor forward rotation and reverse rotation are recorded;Average angle difference is calculated according to the data recorded in the rotation of motor forward and reverse;The first corrected electric angle is obtained by correcting motor electric angle according to the mechanical angle of magnetic encoder feedback and the average angle difference.The application calculates average angle difference according to the data recorded in the rotation of motor forward and reverse, and then calibrates the initial position of permanent magnet synchronous motor, avoids the problem that encoder feedback permanent magnet synchronous motor rotor position is not accurate, and improves the control precision of permanent magnet synchronous motor.

Description

Technical Field

[0001] This invention relates to the field of motor drive control technology, and in particular to a method for initial position calibration of a permanent magnet synchronous motor based on a magnetic encoder. Background Technology

[0002] With the development of permanent magnet material technology and the advancement of power electronics and drive device technology, permanent magnet synchronous motors (PMSMs) are now widely used in industrial manufacturing, aerospace, robotics, and other fields. PMSMs generally employ rotor field-oriented control, and real-time rotor position information is a prerequisite for precise control. Currently, photoelectric encoders or rotary transformers are commonly used to collect position information, but these are bulky and costly. Magnetic encoders offer significant advantages in terms of small size and low cost; however, due to the influence of installation accuracy, the position angle feedback from the magnetic encoder has a certain error, resulting in a deviation between the electrical angle input when controlling the motor rotation and the actual electrical angle when the motor reaches the desired position. Existing initial position calibration methods for PMSMs cannot eliminate the problem of inaccurate rotor position feedback from the magnetic encoder caused by installation accuracy issues, thus affecting the control accuracy of the PMSM. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this invention is to provide an initial position calibration method and device for a permanent magnet synchronous motor that can eliminate the influence of mechanical friction, cogging torque effect, and magnetic encoder installation accuracy on the encoder feedback position during motor rotation, thereby avoiding the problem of inaccurate encoder feedback of the rotor position of the permanent magnet synchronous motor.

[0004] To achieve the above objectives, a first aspect of the present invention provides an initial position calibration method for a permanent magnet synchronous motor based on a magnetic encoder, comprising the following steps:

[0005] The correctness of the motor phase sequence is determined by the change in the setpoint of the motor's electrical angle and the change in the mechanical angle fed back by the magnetic encoder.

[0006] After confirming that the motor phase sequence is correct, record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, the change in motor electrical angle, and the change in mechanical angle fed back by the magnetic encoder during one revolution of the motor in the forward direction.

[0007] Record the given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one reverse rotation of the motor.

[0008] Calculate the average angle difference based on the data recorded from one clockwise rotation of the motor and one counterclockwise rotation of the motor.

[0009] The first corrected electrical angle is obtained by correcting the motor electrical angle based on the mechanical angle fed back by the magnetic encoder and the average angle difference.

[0010] Furthermore, it also includes:

[0011] The second corrected electrical angle is obtained by performing a moving average filter on the corrected first corrected electrical angle.

[0012] Furthermore, it also includes:

[0013] The corrected second corrected electrical angle is corrected using data recorded by the motor rotating one revolution in the forward direction and data recorded by the motor rotating one revolution in the reverse direction to obtain the third corrected electrical angle.

[0014] Furthermore, the recording of the given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one revolution of the motor includes:

[0015] Given a direct-axis current i d The rated current of the motor is i, and the quadrature-axis current is i. q The given motor electrical angle θ is 0. ref Set the value to 0 and record the mechanical angle θ fed back by the magnetic encoder at this time. fb ;

[0016] Increase the given motor electrical angle according to the predetermined change in motor electrical angle until the motor rotates one revolution in the forward direction. Record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, and the change in mechanical angle each time.

[0017] Furthermore, the recording of the given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one reverse rotation of the motor includes:

[0018] Adjust the given motor electrical angle according to the predetermined change in motor electrical angle until the motor electrical angle decreases to 0°, and record each given motor electrical angle, the mechanical angle fed back by the magnetic encoder, and the change in mechanical angle.

[0019] Furthermore, the average angle difference is calculated based on the data recorded from one revolution of the motor in the forward direction and one revolution of the motor in the reverse direction, including:

[0020] The number of motor pole pairs p is calculated according to the first predetermined formula based on the recorded change in the electrical angle of the motor and the change in the mechanical angle fed back by the magnetic encoder.

[0021] The mechanical angle fed back by the magnetic encoder is converted into the electrical angle of the encoder by using the number of pole pairs p of the motor;

[0022] Calculate the electrical angle offset based on the transformed encoder electrical angle and the given motor electrical angle;

[0023] The electrical angle offset calculated based on the encoder electrical angle and the given motor electrical angle for each change is used to calculate the average electrical angle difference according to the second predetermined formula.

[0024] Furthermore, the first predetermined formula is:

[0025]

[0026] Where, ∑Δθ ref ∑Δθ is the sum of all recorded changes in the electrical angle of the motor. fb p is the sum of the mechanical angle changes recorded by all magnetic encoders, where p is the number of pole pairs of the motor.

[0027] Furthermore, the second predetermined formula is:

[0028]

[0029] Where, θ′ fbn θ′ is the mechanical angle fed back by the magnetic encoder. refn For a given electrical angle of the motor, p × θ′ fbn Let θ be the encoder electrical angle of the change, n be the number of mechanical angles fed back by the encoder, and θ be the encoder feedback angle. err_dc The electrical angle is the average angle difference.

[0030] A second aspect of the present invention provides an electronic device comprising:

[0031] One or more processors; and

[0032] A storage device for storing one or more programs, which, when executed by the one or more processors, cause the one or more processors to perform the method as described in the first aspect.

[0033] A third aspect of the present invention provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect.

[0034] This invention calculates the average angle difference based on data recorded from one revolution of the motor in the forward direction and one revolution of the motor in the reverse direction, and then calibrates the initial position of the permanent magnet synchronous motor. This can eliminate the influence of mechanical friction, cogging torque effect and magnetic code installation accuracy on the encoder feedback position during motor rotation, avoid the problem of inaccurate encoder feedback of the permanent magnet synchronous motor rotor position, and improve the control accuracy of the permanent magnet synchronous motor.

[0035] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of an embodiment of the present invention: an initial position calibration method for a permanent magnet synchronous motor based on a magnetic encoder. Detailed Implementation

[0038] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the invention will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0039] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the invention.

[0040] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0041] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0042] like Figure 1 As shown, the first aspect of the present invention provides an initial position calibration method for a permanent magnet synchronous motor based on a magnetic encoder, comprising the following steps:

[0043] Step S100: Determine whether the motor phase sequence is correct based on the change in the motor electrical angle setpoint and the change in the mechanical angle fed back by the magnetic encoder;

[0044] Step S110: After confirming that the motor phase sequence is correct, record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, the change in motor electrical angle, and the change in mechanical angle fed back by the magnetic encoder during one revolution of the motor in the forward direction.

[0045] Step S120: Record the given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one reverse rotation of the motor.

[0046] Step S130: Calculate the average angle difference based on the data recorded by the motor rotating one revolution in the forward direction and the data recorded by the motor rotating one revolution in the reverse direction;

[0047] Step S140: Correct the motor electrical angle based on the mechanical angle fed back by the magnetic encoder and the average angle difference to obtain the first corrected electrical angle.

[0048] In one embodiment of the present invention, step S100 specifically includes: giving a direct-axis current i d The rated current of the motor is i, and the quadrature-axis current is i. q The given value of the electric angle of the motor is θ, which is 0. ref If the given electrical angle is 0, gradually increase the motor electrical angle. That is, if the change in the given electrical angle of the motor is positive, the motor will rotate gradually following the change in the given electrical angle. The mechanical angle fed back by the magnetic encoder is obtained in real time. If the change in the mechanical angle fed back by the magnetic encoder increases, the phase sequence is correct. Otherwise, swap the phases of any two phases in the motor and repeat the above steps until the motor phase sequence is correct.

[0049] In one embodiment of the present invention, step S110 specifically includes:

[0050] Given a direct-axis current i d The rated current of the motor is i, and the quadrature-axis current is i. q The given motor electrical angle θ is 0. ref Set the value to 0 and record the mechanical angle θ fed back by the magnetic encoder at this time. fb ;

[0051] The given motor electrical angle is increased according to the predetermined change in motor electrical angle until the motor rotates one revolution in the forward direction. For example, the change in motor electrical angle Δθ each time... ref =10°. As the given electrical angle increases, the motor rotates in the forward direction. Record the given electrical angle of the motor and the mechanical angle fed back by the magnetic encoder, as well as the change in the mechanical angle, for each rotation. Due to the influence of cogging torque and mechanical friction, there is a certain tracking error between the current angle and the mechanical angle of the motor rotor rotation. To eliminate the tracking error, the motor is rotated in the reverse direction.

[0052] In one embodiment of the present invention, step S120 specifically includes: adjusting a given motor electrical angle down according to a predetermined change in motor electrical angle until the motor electrical angle decreases to 0°, for example, each change in motor electrical angle is Δθ. ref = -10°, as the given electrical angle decreases, the motor rotates in the opposite direction until the motor electrical angle decreases to 0°. Record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, and the change in the mechanical angle each time, so as to eliminate the influence of mechanical friction.

[0053] In one embodiment of the present invention, step S130 specifically includes:

[0054] The number of motor pole pairs p is calculated according to a first predetermined formula based on the recorded changes in the electrical angle of the motor and the changes in the mechanical angle fed back by the magnetic encoder. The first predetermined formula is:

[0055]

[0056] Where, ∑Δθ ref ∑Δθ is the sum of all recorded changes in the electrical angle of the motor. fb p is the sum of the mechanical angle changes recorded by all magnetic encoders, where p is the number of pole pairs of the motor.

[0057] The mechanical angle fed back by the magnetic encoder is transformed into the encoder electrical angle p×θ' by using the number of pole pairs p of the motor. fb Encoder electrical angle p×θ' fb Subtract the given electrical angle θ′ of the motor refn Therefore, the electrical angle offset θ is calculated. err_dc .

[0058] The average electrical angle difference is calculated based on the electrical angle offset calculated from the encoder electrical angle and the given motor electrical angle for each change, according to a second predetermined formula. The second predetermined formula is:

[0059]

[0060] Where, θ′ fbn θ′ is the mechanical angle fed back by the magnetic encoder. refn For a given electrical angle of the motor, p × θ′ fbn Let θ be the encoder electrical angle of the change, n be the number of mechanical angles fed back by the encoder, and θ be the encoder feedback angle. err_dc The electrical angle is the average angle difference.

[0061] Step S140: Correct the motor electrical angle based on the mechanical angle fed back by the magnetic encoder and the average angle difference to obtain a first corrected electrical angle. For example, the first corrected electrical angle is calculated using the following formula.

[0062] θ′ fbe =p×θ′fb -θ err_dc

[0063] Furthermore, due to the presence of cogging torque, the motor rotor tends to remain in a fixed position, causing periodic torque fluctuations that result in additional torque ripples and affect positioning accuracy during calibration. To eliminate the cogging torque effect, a moving average filter is applied to the first corrected electrical angle after the above correction to obtain the second corrected electrical angle. To filter out the cogging torque effect, the window width of the moving average filter is set to one electrical cycle, resulting in the filtered second corrected electrical angle θ'. fbe滤波后 .

[0064] The second corrected electrical angle, after sliding filtering, has eliminated interference from cogging torque effects and only includes nonlinear interference from the magnetic encoder installation. To compensate for this nonlinear interference, a third corrected electrical angle is obtained by correcting the second corrected electrical angle using data recorded from one revolution of the motor in the forward direction and one revolution in the reverse direction. Specifically, a table is created showing the second corrected electrical angles corresponding to each previously given electrical angle. When the motor rotor rotates to the corresponding electrical angle, the electrical angle at that position is corrected using a lookup table to obtain the third corrected electrical angle, thus eliminating nonlinear errors caused by the magnetic encoder installation.

[0065] A second aspect of the present invention provides an electronic device comprising:

[0066] One or more processors; and

[0067] A storage device for storing one or more programs, which, when executed by the one or more processors, cause the one or more processors to perform the method as described in the first aspect.

[0068] A third aspect of the present invention provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect.

[0069] For example, electronic devices include a central processing unit (CPU), which can perform various appropriate actions and processes based on programs stored in read-only memory (ROM) or programs loaded from memory into random access memory (RAM). RAM also stores various programs and data required for system operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0070] The following components are connected to the I / O interface: input sections including touchscreens; output sections including cathode ray tubes (CRTs), liquid crystal displays (LCDs), and speakers; storage sections including hard drives; and communication sections including network interface cards such as LAN cards and modems. The communication sections perform communication processing via networks such as the Internet or Bluetooth. Drives are also connected to the I / O interface as needed. Removable media, such as disks, optical discs, magneto-optical discs, semiconductor memory, TF cards, etc., are installed on the drive as needed so that computer programs read from them can be installed into the storage section as required.

[0071] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium. When the computer program is executed by a central processing unit (CPU), it performs the functions defined in the system of this application.

[0072] In summary, this invention can automatically calibrate the initial position angle of the magnetic encoder, while eliminating the influence of mechanical friction and cogging torque effect on the identification accuracy. Furthermore, it uses a lookup table method to compensate for nonlinear errors caused by the installation accuracy of the magnetic encoder, effectively improving the rotor position feedback accuracy of the magnetic encoder, thereby enhancing the position control accuracy of the permanent magnet synchronous motor.

[0073] It should be noted that the computer-readable medium shown in this invention can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this invention, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0074] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0075] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0076] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, portable hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the control method according to the embodiments of the present invention.

[0077] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0078] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for initial position calibration of a permanent magnet synchronous motor based on a magnetic encoder, characterized in that, Includes the following steps: The correctness of the motor phase sequence is determined by the change in the setpoint of the motor's electrical angle and the change in the mechanical angle fed back by the magnetic encoder. After confirming that the motor phase sequence is correct, record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, the change in motor electrical angle, and the change in mechanical angle fed back by the magnetic encoder during one revolution of the motor in the forward direction. Record the given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one reverse rotation of the motor. Calculate the average angle difference based on the data recorded from one clockwise rotation of the motor and one counterclockwise rotation of the motor. The average angle difference is calculated based on data recorded from one revolution of the motor in the forward direction and one revolution of the motor in the reverse direction, including: The number of motor pole pairs p is calculated according to the first predetermined formula based on the recorded change in the electrical angle of the motor and the change in the mechanical angle fed back by the magnetic encoder. The mechanical angle fed back by the magnetic encoder is converted into the electrical angle of the encoder by using the number of pole pairs p of the motor; Calculate the electrical angle offset based on the transformed encoder electrical angle and the given motor electrical angle; The electrical angle offset calculated based on the encoder electrical angle and the given motor electrical angle for each change is used to calculate the average electrical angle difference according to the second predetermined formula. The first corrected electrical angle is obtained by correcting the motor electrical angle based on the mechanical angle fed back by the magnetic encoder and the average angle difference.

2. The initial position calibration method for a permanent magnet synchronous motor as described in claim 1, characterized in that, Also includes: The second corrected electrical angle is obtained by performing a moving average filter on the corrected first corrected electrical angle.

3. The initial position calibration method for a permanent magnet synchronous motor as described in claim 2, characterized in that, Also includes: The corrected second corrected electrical angle is corrected using data recorded by the motor rotating one revolution in the forward direction and data recorded by the motor rotating one revolution in the reverse direction to obtain the third corrected electrical angle.

4. The initial position calibration method for a permanent magnet synchronous motor as described in claim 1, characterized in that, The recording includes the following: a given electrical angle of the motor, the mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder during one revolution of the motor in the forward direction: Given a direct-axis current i d The rated current of the motor is i, and the quadrature-axis current is i. q The given motor electrical angle θ is 0. ref Set the value to 0 and record the mechanical angle θ fed back by the magnetic encoder at this time. fb ; Increase the given motor electrical angle according to the predetermined change in motor electrical angle until the motor rotates one revolution in the forward direction. Record the given motor electrical angle, the mechanical angle fed back by the magnetic encoder, and the change in mechanical angle each time.

5. The initial position calibration method for a permanent magnet synchronous motor as described in claim 4, characterized in that, The recording includes the following: a given electrical angle of the motor during one reverse rotation of the motor, a mechanical angle fed back by the magnetic encoder, the change in the electrical angle of the motor, and the change in the mechanical angle fed back by the magnetic encoder. Adjust the given motor electrical angle according to the predetermined change in motor electrical angle until the motor electrical angle decreases to 0°, and record each given motor electrical angle, the mechanical angle fed back by the magnetic encoder, and the change in mechanical angle.

6. The initial position calibration method for a permanent magnet synchronous motor as described in claim 1, characterized in that, The first predetermined formula is: in, This is the sum of all recorded changes in the electrical angle of the motor. p is the sum of the mechanical angle changes recorded by all magnetic encoders, where p is the number of pole pairs of the motor.

7. The initial position calibration method for a permanent magnet synchronous motor as described in claim 1, characterized in that, The second predetermined formula is: in, The mechanical angle fed back by the magnetic encoder. Given the electrical angle of the motor, Let n be the encoder electrical angle of the change, and n be the number of mechanical angle feedbacks from the encoder. The electrical angle is the average angle difference.

8. An electronic device, characterized in that, include: One or more processors; as well as A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to perform the method as described in any one of claims 1-7.

9. A computer-readable medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-7.

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