Method and device for calibrating zero position of electric angle of permanent magnet synchronous motor under limited rotation angle constraint and readable storage medium thereof

Abstract

The invention discloses a permanent magnet synchronous motor electrical angle zero calibration method and device under limited rotation angle constraint and a readable storage medium thereof, and relates to the technical field of motor servo control, and the method comprises the following steps: applying a direct current to a motor straight shaft, enabling a motor rotor to be aligned with an electrical angle zero point, and recording a reading as an initial zero assumption value; the motor is controlled to move by a preset angle in the positive direction from the position corresponding to the initial zero assumed value, and a feedback value is read; calculating a difference value between the feedback value and the initial zero assumed value, and judging whether the direction of the encoder is correct or not according to the plus or minus of the difference value; when it is judged that the direction of the encoder is correct, the motor is controlled to reversely move by a preset angle, and the feedback value is read again; the method has the beneficial effects that the problems of multiplicity of solutions and directivity of the zero position of the motor in the limited space are solved, and the limitation of a traditional calibration method on the rotation space of the motor is overcome.

Description

Technical Field

[0001] This invention relates to the field of motor servo control technology, and in particular to a method, apparatus and readable storage medium for zero-position calibration of electrical angle of permanent magnet synchronous motor under finite rotation angle constraints. Background Technology

[0002] Permanent magnet synchronous motors are widely used in robotics, precision automation, aerospace and other fields due to their high power density and high efficiency. In many applications, the mechanical rotation range of the motor is limited to a very small angle (e.g., less than 30°), such as robot joints, servo motors, valve actuators, etc.

[0003] To achieve high-precision servo control of a motor (such as field-oriented control), the primary prerequisite is obtaining an accurate absolute rotor position, i.e., calibrating the motor's zero position. Traditional calibration methods have the following limitations:

[0004] Index signal method (Z-pulse method): Requires the motor to rotate at least 360°, using the encoder's Z-phase signal to locate the zero position. This is completely impossible to achieve on motors with limited rotation angles.

[0005] A simple DC alignment method involves applying a DC current to the motor's d-axis to attract the rotor to a known electrical angular zero. However, for motors with more than one pole pair (P represents the pole pair number), there exists an electrical angular "zero" every 360° / P within the mechanical space. Within narrow mechanical constraints, the zero found by DC alignment may be invalid because it is outside the mechanical stop. Furthermore, this method cannot automatically identify and correct problems caused by incorrect wiring leading to reverse motor rotation.

[0006] Therefore, existing technologies cannot automatically and reliably complete the precise calibration of the motor's zero position within a limited turning angle, which brings great inconvenience to equipment debugging. Summary of the Invention

[0007] The main objective of this invention is to propose a method, apparatus, and readable storage medium for zero-position calibration of the electrical angle of a permanent magnet synchronous motor under finite rotation angle constraints, aiming to solve the technical problem of being unable to automatically and reliably complete the accurate calibration of the motor's zero position within a finite rotation angle.

[0008] To achieve the above objectives, the present invention proposes a method for zero-position calibration of the electrical angle of a permanent magnet synchronous motor under finite rotation angle constraints, comprising the following steps:

[0009] Initial alignment steps: Apply DC current to the direct shaft of the motor to align the motor rotor to a zero position at an electrical angle, and record the reading fed back by the position sensor at this time as the initial zero position assumption value;

[0010] Forward movement and data acquisition steps: Control the motor to move from the position corresponding to the initial zero position assumption value in the positive direction by a preset angle, and read the actual feedback value of the position sensor at this time;

[0011] Direction determination steps: Calculate the difference between the actual feedback value and the initial zero position assumption value, and determine whether the direction of the motor encoder is correct based on the sign of the difference;

[0012] Effective zero-position verification and determination steps: When the encoder direction is determined to be correct, the control motor moves in the opposite direction by the preset angle, and the feedback value of the position sensor is read again; by analyzing the relationship between this feedback value and the initial zero-position assumption value, the initial zero-position assumption value is verified to be within the effective mechanical space, and the final absolute zero position is determined accordingly.

[0013] In one embodiment, the effective zero-position verification and determination step specifically includes:

[0014] If the motor can move the preset angle in the opposite direction, the initial zero position assumption value is determined to be valid and is identified as the final zero position.

[0015] If the motor's movement in the opposite direction is blocked by a mechanical limit, the initial zero-position assumption value is compensated for by an angle to obtain a new zero-position assumption value. The forward movement and acquisition steps, the direction judgment steps, and this step are repeated until a valid zero position that can be verified is found.

[0016] In one embodiment, the angle compensation value is less than the mechanical angle corresponding to one electrical cycle of the motor.

[0017] In one embodiment, the direction determination step includes:

[0018] If the difference is positive, the encoder direction is determined to be correct;

[0019] If the difference is negative, the encoder direction is determined to be incorrect, and a direction correction step is performed.

[0020] In one embodiment, the orientation correction step includes:

[0021] The raw angle values ​​read by the position sensor are subjected to a complementary operation to correct the direction at the software level;

[0022] The new angle value obtained after correction is used as the new zero-point reference, and the forward movement and acquisition steps are returned to restart the verification process.

[0023] In one embodiment, the preset angle is 1 / 1000 to 1 / 2 of the mechanical angle limited by the motor.

[0024] In one embodiment, the mechanical rotation range angle is less than or equal to the mechanical angle corresponding to one electrical cycle of the motor, and the preset angle is less than or equal to 2°.

[0025] In one embodiment, during the initial alignment step, the applied direct-axis DC current intensity is 1 / 10 to 1 / 2 of the motor's rated current.

[0026] Secondly, this invention provides a system for calibrating the electrical angle zero position of a permanent magnet synchronous motor under finite rotation angle constraints, used to implement the above-mentioned motor small angle zero position calibration method, the system comprising:

[0027] The control unit is configured to perform the various steps of the method;

[0028] The driver, electrically connected to the control unit, is used to receive control commands and apply corresponding voltage or current to the motor;

[0029] A position sensor is used to detect the position information of the motor rotor in real time and feed it back to the control unit.

[0030] Thirdly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, is capable of implementing the steps of the above-described method.

[0031] The technical solution of this invention combines DC alignment and forward / reverse movement verification, and uses logical judgment to intelligently solve the problems of multiple solutions for motor zero position and directionality in a limited space. It overcomes the limitations of traditional calibration methods on the motor rotation space, improves the practicality of the calibration method, and adopts a preset angle smaller than the mechanical limit angle during calibration. By setting the angle compensation value related to the mechanical angle of the motor electrical cycle, the effective zero position is gradually searched, which can automatically identify and correct encoder direction errors, improve the efficiency and accuracy of calibration, and reduce the difficulty of equipment debugging. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating the method for zero-position calibration of the electrical angle of a permanent magnet synchronous motor under finite rotation angle constraints provided by the present invention.

[0034] Figure 2 The judgment block diagram of the method for zero-position calibration of electrical angle of permanent magnet synchronous motor under finite rotation angle constraint provided by the present invention

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that if directional indicators (such as up, down, left, right, front, back, etc.) are involved in the embodiments of this invention, these directional indicators are only used to explain the relative positional relationships and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. Unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0038] Furthermore, if the embodiments of the present invention involve descriptions using terms such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the use of "and / or" or "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0039] The method for zero-position calibration of electrical angle of permanent magnet synchronous motor under finite rotation angle constraint proposed in this invention includes the following steps:

[0040] Initial alignment steps: Apply DC current to the direct shaft of the motor to align the motor rotor to a zero position at an electrical angle, and record the reading fed back by the position sensor at this time as the initial zero position assumption value;

[0041] Forward movement and data acquisition steps: Control the motor to move from the position corresponding to the initial zero position assumption value in the positive direction by a preset angle, and read the actual feedback value of the position sensor at this time;

[0042] Direction determination steps: Calculate the difference between the actual feedback value and the initial zero position assumed value, and determine whether the direction of the motor encoder is correct based on the sign of the difference;

[0043] Valid zero-position verification and determination steps: When the encoder direction is determined to be correct, the control motor moves in the opposite direction by a preset angle, and the feedback value of the position sensor is read again; by analyzing the relationship between this feedback value and the initial zero-position assumption value, the initial zero-position assumption value is verified to be within the effective mechanical space, and the final absolute zero position is determined accordingly.

[0044] In one embodiment, the valid zero-point verification and determination step specifically includes:

[0045] If the motor can move a preset angle in the opposite direction, the initial zero position assumption value is determined to be valid and is identified as the final zero position.

[0046] If the motor's movement in the opposite direction is blocked by a mechanical limit, the initial zero position assumption value is compensated for by angle to obtain a new zero position assumption value. The forward movement and acquisition steps, the direction judgment steps, and this step are repeated until a valid zero position that can be verified is found.

[0047] In one embodiment, the angle compensation value is less than the mechanical angle corresponding to one electrical cycle of the motor.

[0048] In one embodiment, the direction determination step includes:

[0049] If the difference is positive, the encoder direction is determined to be correct;

[0050] If the difference is negative, the encoder direction is determined to be incorrect, and a direction correction step is performed.

[0051] In one embodiment, the orientation correction step includes:

[0052] The raw angle values ​​read by the position sensor are subjected to a complementary operation to correct the direction at the software level;

[0053] The new angle value obtained after correction is used as the new zero reference, and the forward movement and acquisition steps are returned to restart the verification process.

[0054] In one embodiment, the preset angle is 1 / 1000 to 1 / 2 of the mechanical angle limited by the motor.

[0055] In one embodiment, the mechanical rotation range angle is less than or equal to the mechanical angle corresponding to one electrical cycle of the motor, and the preset angle is less than or equal to 2°.

[0056] In one embodiment, during the initial alignment step, the applied direct-axis DC current intensity is 1 / 10 to 1 / 2 of the motor's rated current.

[0057] Secondly, this invention provides a system for zero-position calibration of the electrical angle of a permanent magnet synchronous motor under finite rotation angle constraints, used to implement the above-mentioned small-angle zero-position calibration method for the motor. The system includes:

[0058] The control unit is configured to execute the various steps of the method;

[0059] The driver, electrically connected to the control unit, is used to receive control commands and apply corresponding voltage or current to the motor;

[0060] A position sensor is used to detect the position information of the motor rotor in real time and feed it back to the control unit.

[0061] Thirdly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the implementation of the steps of the above-described method.

[0062] The following description, using a preferred embodiment, illustrates the content related to the above embodiments:

[0063] Example 1:

[0064] The overall process of the method is as follows Figure 2 As shown, the main steps include:

[0065] S1: Initial DC Alignment

[0066] The control driver applies a direct-axis current to the motor (setting the q-axis voltage Uq = 0 and the d-axis voltage Ud to 1 / 5 of its rated value) to stably align the rotor to the d-axis position at an electrical angle. The reading fed back by the position sensor (such as an absolute encoder) at this point is recorded and used as the initial zero-position assumption value Z0.

[0067] S2: Forward Movement and Data Acquisition

[0068] The control motor moves from the Z0 position obtained from S1 in the positive direction by a preset angle C (C is less than the mechanical limit angle of the motor), that is, to the commanded position Z0+C. The actual feedback value A of the position sensor at this time is read.

[0069] S3: Directional Consistency Judgment

[0070] Calculate the difference (A-Z0) between the actual feedback value A and the initial zero position value Z0, and determine the encoder direction based on the difference:

[0071] Case 1: Correct direction. If (A-Z0)>0, it means the actual direction of the motor is consistent with the control command, and the encoder direction is correct. Then proceed to step S4.

[0072] Case 2: Incorrect direction. If (A-Z0) < 0, it means the actual direction of the motor is opposite to the control command. Then, execute step S5 to correct the direction.

[0073] Case 3: Cannot be determined. If (A≈Z0), it means the motor is not moving in the positive direction. Then proceed to step S5.

[0074] S4: Verification and determination of valid zeros (resolving multiple solutions)

[0075] Provided the direction is correct, control the motor to move in the opposite direction by a preset angle C, that is, to reach the command position Z0-C, and read the actual feedback value B at this time.

[0076] S41: If B < Z0, it indicates that the motor can move normally in both forward and reverse directions, and the initial zero position assumed value Z0 is within the effective mechanical space. Then, determine that Z0 is the final effective zero position.

[0077] S42: If B ≈ Z0, it indicates that the motor is blocked by mechanical limit when moving in the reverse direction and fails to reach the commanded position. This proves that the electrical cycle point corresponding to the initial Z0 is invalid (outside the mechanical stop). At this time, apply an angle compensation value to the zero position angle assumed value (set as 0 + n×D, where D is a small angle step and n is the number of times of adding the compensation value) to obtain a new zero position assumed value Z0_new. Repeat steps S2 to S4 until the condition B < Z0 is satisfied. At this time, the effective zero position is the initial Z0 - n×D.

[0078] S5: Encoder direction correction

[0079] When it is judged as the wrong direction in S3, perform a complementary operation on the original angle value read by the position sensor. The specific method of the complementary operation is: the new angle value = 360° - the original angle value, so as to correct the direction at the software level. Assign the corrected new zero position value (360 - Z0) to Z0, and then return to step S2 to restart the entire verification process with the new and correctly directed zero position reference.

[0080] Next, in combination with the second preferred embodiment, the content involved in the above embodiment will be described:

[0081] Embodiment 2:

[0082] In this embodiment, a permanent magnet synchronous motor with a pole pair number P = 3 and a mechanical limit of 30° is taken as an example. The magnetic encoder used can output 3600 unique position codes per rotation, that is, 360° mechanical angle, i.e., the encoder value N = mechanical angle × 10.

[0083] S1: Apply direct current to the motor through the driver (Uq = 0, Ud = rated value / 5), and align the motor rotor to the d-axis. Read the absolute encoder value and record it as the initial zero position assumed value Z0 = 2500 (counting unit).

[0084] S2: Command the motor to move forward by a preset angle C = 2° (corresponding to an increase in encoder count), that is, move to the position 2500 + C, and read the actual feedback value A = 2520.

[0085] S3: Calculate A - Z0 = 20 > 0, judge that the direction is correct, and enter S4.

[0086] S4: Command the motor to move backward by 2°, to the position 2500 - C, and read the actual feedback value B.

[0087] Scenario 1 (Success): B = 2480. Since 2480 < 2500, verification passed. Zero-position calibration successful.

[0088] The final effective zero is 2500.

[0089] Scenario 2 (Iteration Required): B ≈ 2500. This indicates that reverse movement is blocked, and Z0 is invalid. Set D = 1°, and start trying from 1. The new zero position is assumed to be Z0_new = 2500 + 10 = 2510. Repeat S2-S4. When trying until n = 5, Z0_new = 2550. At this point, after moving forward, A = 2570, and after moving backward, B = 2530 < 2550, verifying success. The final valid zero position is the initial Z0 - n × D × 10 = 2500 - 50 = 2450.

[0090] Theoretical Analysis of DC Alignment Method

[0091] DC alignment, commonly referred to as "rotor initial position positioning" or "d-axis alignment" in permanent magnet synchronous motor control, is theoretically based on the torque generation principle of permanent magnet synchronous motors.

[0092] electromagnetic torque formula

[0093] The electromagnetic torque formula for a permanent magnet synchronous motor can be simplified to:

[0094] Te=(3 / 2)·P·[Ψpm·Iq+(Ld-Lq)·Id·Iq]

[0095] Te: Electromagnetic torque

[0096] P: Number of pole pairs of the motor

[0097] Ψpm: Magnetic flux linkage generated by a permanent magnet (a fixed value)

[0098] Ld, Lq: Direct-axis (d-axis) and quadrature-axis (q-axis) inductances

[0099] Id, Iq: Direct-axis and quadrature-axis currents

[0100] When we set the q-axis current (Iq) to 0, the result of the entire torque formula is Te = 0. This means that the motor will not generate any tangential torque for rotation.

[0101] The physical process of D-axis alignment

[0102] Uq = 0: This is equivalent to controlling Iq = 0. According to the formula, the torque Te is 0 at this time, and the motor has no tendency to rotate.

[0103] Applying a Ud (Id≠0): This will generate a fixed current field in the stator winding of the motor, which is equivalent to a stationary magnetic field.

[0104] Mathematical Model of Motor in Stationary Coordinate System and Alignment Target

[0105] The voltage equations and flux linkage equations of the permanent magnet synchronous motor in the stationary α-β coordinate system are as follows:

[0106] Voltage equation:

[0107] U α =R s i α +dψ α / dt

[0108] U β =R s i β +dψ β / dt

[0109] U α U β Components of stator voltage on the α and β axes

[0110] R s Stator phase resistance

[0111] i α i β Components of stator current on the α and β axes

[0112] ψ α , ψ β Components of stator flux linkage on the α and β axes

[0113] dψ α / dt: Differential of stator flux linkage with respect to time

[0114] The flux linkage equation (which includes the effect of the rotor permanent magnet flux linkage) is as follows:

[0115] ψ α =L s i α +ψ pm cos(θ e )

[0116] ψ β =L s i β +ψ pm sin(θ e )

[0117] ψ α , ψ β Components of stator flux linkage on the α and β axes

[0118] i α i β Components of stator current on the α and β axes

[0119] θe: Rotor electrical angle

[0120] Ψpm: Permanent magnet magnetic flux

[0121] Ls: refers to the stator synchronous inductance under specific assumptions.

[0122] The theoretical goal of alignment: to achieve the rotor position angle θ by injecting a DC signal. e It is precisely positioned to 0 (or a known fixed value). When alignment is complete, the d-axis (rotor pole axis) coincides with the α-axis (stator A-phase winding axis).

[0123] Steady-state model and magnetic field relationship under DC excitation

[0124] When a constant voltage vector (U) is applied to the motor d U q =0) and wait for the system to reach steady state. Since the current derivative is zero, the voltage equation in the dq coordinate system simplifies to:

[0125] U d =R s I d

[0126] U q =R s I q +ω e ψ pm =0

[0127] Ud, Uq: d-axis and q-axis components of the stator voltage.

[0128] Id, Iq: d-axis and q-axis components of the stator current.

[0129] R s Stator phase resistance

[0130] ω e : The electric angular velocity of the rotor

[0131] ψ pm Permanent magnet magnetic flux

[0132] Because the rotor is forcibly locked and the speed ω e =0, the second equation directly yields I q =0. The obtainable "U" q =0 is equivalent to control I q =0" is completely consistent.

[0133] At this time, the amplitude of the stator synthesized magnetomotive force (MMF) generated inside the motor is F. s =N·I s (Fs Stator magnetomotive force, N is the number of winding turns, I s The current flowing through the stator windings is fixed in a direction coinciding with the d-axis. The magnetomotive force F generated by the rotor permanent magnets... r Under the influence of the magnetic field, it will align with the stator magnetomotive force, so that the axes of the two coincide, thereby achieving a stable state with the minimum magnetic circuit reluctance and the lowest system magnetic common energy.

[0134] The theoretical essence of DC alignment is to utilize the interaction between the static magnetic field generated by the Id current and the magnetic field of the rotor permanent magnet to force the rotor to be positioned at the d-axis electrical zero position. It provides an accurate initial reference point (Z0) for the entire calibration process.

[0135] It should be understood that the terms "one embodiment" or "one example" throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in one example" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0136] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0137] 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 this application. 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 is particularly important to note that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can 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.

[0138] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for calibrating the electrical angle zero position of a permanent magnet synchronous motor under limited rotation angle constraint, characterized in that, The method comprises the following steps: An initial alignment step: a direct-axis direct current is applied to the direct axis of the motor, so that the motor rotor is aligned to a zero position at an electrical angle, and a reading value of a position sensor feedback at this time is recorded as an initial zero assumption value; A forward movement and collection step: the motor is controlled to move a preset angle in a positive direction from a position corresponding to the initial zero assumption value, and an actual feedback value of the position sensor at this time is read; A direction judgment step: a difference between the actual feedback value and the initial zero assumption value is calculated, and whether the direction of the motor encoder is correct is judged according to a positive or negative situation of the difference; An effective zero verification and determination step: when it is judged that the direction of the encoder is correct, the motor is controlled to move the preset angle in a reverse direction, and a feedback value of the position sensor is read again; whether the initial zero assumption value is located in an effective mechanical space is verified by analyzing a relationship between the feedback value and the initial zero assumption value, and a final absolute zero is determined according to the verification.

2. The method for permanent magnet synchronous motor electrical angle zero position calibration under finite rotation angle constraint according to claim 1, characterized in that, The effective zero verification and determination step specifically comprises: If the motor can move the preset angle in the reverse direction, it is determined that the initial zero assumption value is effective, and the initial zero assumption value is determined as the final zero; If the movement of the motor in the reverse direction is blocked by mechanical limiting, an angle compensation is performed on the initial zero assumption value to obtain a new zero assumption value, and the forward movement and collection step, the direction judgment step and the step are repeatedly executed until an effective zero that can pass the verification is found.

3. The method for permanent magnet synchronous motor electrical angle zero position calibration under finite rotation angle constraint according to claim 2, characterized in that: The angle compensation value is less than a mechanical angle corresponding to one electrical period of the motor.

4. The method of permanent magnet synchronous motor electrical angle zero position calibration under limited rotation angle constraint of claim 1, wherein: In the direction judgment step: If the difference is positive, it is determined that the direction of the encoder is correct; If the difference is negative, it is determined that the direction of the encoder is incorrect, and a direction correction step is executed.

5. The method for permanent magnet synchronous motor electrical angle zero position calibration under finite rotation angle constraint according to claim 4, characterized in that: The direction correction step comprises: A complementary operation is performed on an original angle value read by the position sensor to correct the direction at a software level; A new angle value obtained after the correction is taken as a new zero reference, and the forward movement and collection step is returned to restart the verification process.

6. The method of permanent magnet synchronous motor electrical angle zero position calibration under limited rotation angle constraint of claim 1, wherein: The preset angle is 1 / 1000 to 1 / 2 of a limited mechanical angle of the motor.

7. The method of permanent magnet synchronous motor electrical angle zero position calibration under finite rotation angle constraint according to claim 6, characterized in that: The mechanical rotation range angle is less than or equal to a mechanical angle corresponding to one electrical period of the motor, and the preset angle is less than or equal to 2°.

8. The method of permanent magnet synchronous motor electrical angle zero position calibration under limited rotation angle constraint of claim 1, wherein: In the initial alignment step, an intensity of the applied direct-axis direct current is 1 / 10 to 1 / 2 of a rated current of the motor.

9. A system for calibrating the electrical angle zero position of a permanent magnet synchronous motor under limited rotation angle constraints, for implementing the method for calibrating the small angle zero position of a motor according to any one of claims 1 to 8, characterized in that: The system comprises: A control unit configured to execute various steps of the method; A driver electrically connected with the control unit, used for receiving a control instruction and applying a corresponding voltage or current to the motor; A position sensor used for detecting position information of the motor rotor in real time and feeding back to the control unit.

10. A computer readable storage medium storing a computer program, characterized in that: The computer program, when executed by a processor, can implement the steps of the method in any one of claims 1 to 8.

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