Direct-current brushless motor high-precision position control method and system based on electrical angle control

Abstract

The invention discloses a direct current brushless motor high-precision position control method and system based on electrical angle control, and relates to the technical field of motor control methods. According to the direct-current brushless motor high-precision position control method based on electrical angle control, a target position is converted into an electrical angle target value, electrical angle integral feedback and a dynamic stepping adjustment mechanism are combined, and sensorless direct position closed-loop control is achieved. According to the direct current brushless motor high-precision position control method based on the electrical angle control, a control method based on the electrical angle is adopted, high-precision position control independent of a high-precision physical sensor is achieved, the system cost is remarkably reduced, and the anti-interference capability is improved. Meanwhile, by introducing an ultra-low-speed motion control mode and an exception handling mechanism, the stability problem of traditional PID control at a low speed is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control methods, in particular to a high-precision position control method and system for a DC brushless motor based on electric angle control. BACKGROUND

[0002] With the development of industrial automation and precision manufacturing, DC brushless motors are widely used in robots, numerical control machine tools, precision optical platforms and other fields due to their high efficiency, low noise and long service life.

[0003] Traditional DC brushless motor position servo must install a high-precision mechanical position sensor such as a 17-bit or more optical encoder or magnetic grid on the motor shaft or load end, and realize positioning through a multi-level nested structure of "mechanical angle -> position loop PID -> speed loop PID -> current loop PID", which has the following disadvantages:

[0004] First, the sensor has high cost, large size, poor anti-pollution and anti-shock, and its reliability decreases in clean or harsh environments such as semiconductors, medical treatment, aerospace, etc.

[0005] Second, the resolution of the mechanical sensor and the installation error directly determine the positioning accuracy of the system, and it is difficult to meet the needs of high precision and low cost at the same time.

[0006] Third, the multi-level PID in series causes large response delay, and the system is prone to crawling, jittering or even out of step at low or ultra-low speed, and is sensitive to load disturbance and current limiting, so it cannot achieve precise position control at low or ultra-low speed. In view of the deficiencies of the prior art, the present application provides a high-precision position control method and system for a DC brushless motor based on electric angle control to solve the above problems. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a high-precision position control method and system for a DC brushless motor based on electric angle control, which adopts a control method based on electric angle to achieve high-precision position control without relying on high-precision physical sensors, significantly reducing system cost and improving anti-interference ability. At the same time, by introducing an ultra-low speed motion control mode and an abnormal processing mechanism, the stability problem of traditional PID control at low speed is solved.

[0008] To achieve the above purpose, the present application realizes the following technical scheme: a high-precision position control method for a DC brushless motor based on electric angle control, comprising the following steps:

[0009] S1: receiving an externally input target position control quantity, a speed limit value and a current limit value;

[0010] S2: converting the target position control quantity into an absolute position target value in units of motor electric angle;

[0011] S3: Obtain an integral value of a current motor electrical angle as an absolute position feedback value;

[0012] S4: Calculate a difference between the absolute position target value and the absolute position feedback value to obtain a position control error;

[0013] S5: Determine an electrical angle increment of a current vector control period according to the position control error, an electrical angle step value limit, and a current limit value;

[0014] S6: Add the current electrical angle value and the electrical angle increment to update an electrical angle value of a next control period;

[0015] S7: Perform current sampling, coordinate transformation, and PID current regulation based on the updated electrical angle value to generate a three-phase voltage control signal;

[0016] S8: Output a three-phase motor driving signal through pulse width modulation to complete a vector control period.

[0017] Preferably, the conversion process in step S2 comprises:

[0018] If the absolute position control mode, directly calculate the electrical angle absolute position target value according to the target position control quantity;

[0019] If the relative position control mode, fuse the target position control quantity and the current electrical angle value to obtain the electrical angle absolute position target value.

[0020] Preferably, the target position control quantity is a load end position in radian units, and the conversion formula to electrical angle units is:

[0021]

[0022] Wherein, is the electrical angle position target value, is the load end target position, N is the reduction ratio, P is the motor pole pair number, and K is the electrical angle resolution.

[0023] Preferably, the electrical angle integral value in step S3 is obtained in the following manner:

[0024] If the motor is equipped with a high-precision position sensor, obtain the initial electrical angle value based on the sensor data;

[0025] If the motor is not equipped with a position sensor, obtain the initial electrical angle value through a non-inductive position estimation algorithm.

[0026] Preferably, the determination of the electrical angle step value in step S5 further comprises:

[0027] The single increment and maximum value of the electrical angle step value are dynamically adjusted according to the motor load state and the current limit value.

[0028] Preferably, the current sampling in step S7 comprises:

[0029] According to the current electrical angle value, a phase current sampling mode is selected, and Clarke transformation and Park transformation are performed to obtain current feedback values in the dq coordinate system.

[0030] Preferably, the method further comprises a super-low-speed motion control mode, wherein:

[0031] The speed control quantity is converted into an electrical angle step value, and the calculation formula is:

[0032]

[0033] wherein, is the electrical angle step value, is a load end speed control quantity, and F is a vector control frequency.

[0034] Preferably, in the super-low-speed motion control mode, the calculation formula of the minimum speed of the motor is:

[0035] .

[0036] Preferably, the method further comprises an abnormality processing mechanism:

[0037] If it is detected that the electrical angle error exceeds a threshold value, the driving current is dynamically adjusted or the electrical angle step value is limited to prevent the motor from jumping.

[0038] The second aspect of the application discloses a high-precision position control system of a DC brushless motor based on electrical angle control, which is applied to the high-precision position control method of the DC brushless motor based on electrical angle control and comprises:

[0039] A control data receiving module receives a target position control quantity, a speed limit value and a current limit value input from outside;

[0040] An electrical angle conversion module converts the target position control quantity into an absolute position target value in units of motor electrical angle;

[0041] An electrical angle integration module is configured to obtain an integral value of a current motor electrical angle as an absolute position feedback value;

[0042] An error calculation module is configured to calculate a difference between the absolute position target value and the absolute position feedback value to obtain a position control error;

[0043] An electrical angle increment control module is configured to determine an electrical angle increment of a current vector control period according to the position control error, an electrical angle step limit, and a current limit value;

[0044] An electrical angle update module is configured to add the current electrical angle value and the electrical angle increment to update an electrical angle value of a next control period;

[0045] A vector control module is configured to perform current sampling, coordinate transformation, and PID current regulation based on the updated electrical angle value to generate a three-phase voltage control signal;

[0046] A drive output module is configured to output a three-phase motor drive signal through pulse width modulation to complete one vector control period.

[0047] Technical effects and advantages of the present application:

[0048] 1. The DC brushless motor high-precision position control method based on electrical angle control converts the target position control quantity input from the outside into an absolute position target value in units of motor electrical angle, and uses the electrical angle integral value as the absolute position feedback value, to realize direct control of the motor position. This method eliminates the need for expensive high-precision position sensors, and instead achieves high-resolution position closed-loop control through purely electrical control means, significantly reducing system cost. At the same time, since the control process does not rely on physical sensors, the system's anti-interference ability is enhanced, and the control response is more direct and faster, thereby improving the accuracy and stability of position control.

[0049] 2. The DC brushless motor high-precision position control method based on electrical angle control proposes a super-low speed motion control mode, which converts the speed control quantity into an electrical angle step value to achieve smooth operation of the motor at extremely low speeds. In this mode, the motor's minimum speed is only limited by the control frequency and the electrical angle resolution, and can reach a few percent per minute or even lower, and the speed control accuracy and stability are completely determined by the clock and calculation accuracy of the electronic system, avoiding the crawling and jitter phenomena that may occur in traditional PID control at low speeds, providing a solution for scenarios that require extremely low speed and smooth operation, such as biological microscope observation.

[0050] 3. The DC brushless motor high-precision position control method based on electrical angle control includes an abnormality handling mechanism that can dynamically adjust the drive current or limit the electrical angle step value when the electrical angle error is detected to exceed the threshold value, effectively preventing motor stepping and improving the robustness and long-term reliability of the system. This mechanism ensures that the motor maintains stable control performance under various load conditions and abnormal operating conditions, reducing system failures and downtime caused by control failure. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0052] Figure 1 The flow chart of the method of the present application;

[0053] Figure 2 The position control mode determination chart of the present application;

[0054] Figure 3 The electric angle acquisition mode determination chart of the present application;

[0055] Figure 4 The electric angle increment control logic chart of the present application;

[0056] Figure 5 The current sampling and conversion flow chart of the present application;

[0057] Figure 6 The ultra-low speed motion control mode chart of the present application;

[0058] Figure 7 The abnormality processing mechanism logic chart of the present application. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below with the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0060] The present embodiment discloses a high-precision position control method of a DC brushless motor based on electric angle control. According to the drawings attached Figure 1 to the drawings attached Figure 7 The method comprises the following steps:

[0061] S1: receiving an externally input target position control quantity, a speed limit value and a current limit value;

[0062] S2: converting the target position control quantity into an absolute position target value in units of motor electric angle;

[0063] S3: obtaining an integral value of the current motor electric angle as an absolute position feedback value;

[0064] S4: Calculate the difference between the absolute position target value and the absolute position feedback value to obtain the position control error;

[0065] S5: Determine the electrical angle increment for the current vector control period based on the position control error, the electrical angle step limit, and the current limit value;

[0066] S6: Add the current electrical angle value and the electrical angle increment to update the electrical angle value for the next control period;

[0067] S7: Based on the updated electrical angle value, perform current sampling, coordinate transformation, and PID current regulation to generate three-phase voltage control signals;

[0068] S8: Output three-phase motor drive signals through pulse width modulation to complete one vector control period.

[0069] The above method constructs the control flow framework of the present application. The method receives the target position control quantity, speed limit value, and current limit value input from the outside, converts the target position into an electrical angle target value, and combines electrical angle integral feedback and dynamic step adjustment mechanism to realize direct position closed-loop control without sensors.

[0070] The principle of the method is to convert the traditional position loop control that relies on high-precision physical sensors into "virtual position" control based on the electrical characteristics of the motor (electrical angle). S1 is the control entrance, which receives upper-layer application instructions. S2 is the key conversion step, which maps the physical position (such as millimeters, radians) understood by the user to the electrical angle value relied on by the internal control of the motor, establishing a bridge between the external physical world and the internal electrical control. S3 continuously tracks the absolute electrical angle position of the motor rotor by integrating the electrical angle increment. This method converts speed information into position information, i.e., electrical angle change rate, without directly measuring the absolute position.

[0071] S4 and S5 constitute the core of the position loop, but unlike traditional PID, the output is not a direct speed or torque command, but an electrical angle increment. This is equivalent to directly planning the exact electrical phase that the rotor should be in the next control period, achieving "direct control" of the position rather than "indirect regulation", thereby responding faster and more accurately. S6 updates the electrical angle set value. S7 and S8 are standard vector control (FOC) processes, which function to generate the required torque to drive the rotor to the electrical angle position set by S6. The advantage of the entire scheme is that it eliminates the need for expensive high-precision position sensors, achieves extremely high-resolution position closed-loop control through pure electrical control, significantly reduces system cost, the system is not affected by sensor noise, and the anti-interference ability is enhanced, the control response is more direct.

[0072] The conversion process in step S2 includes:

[0073] If it is an absolute position control mode, the absolute position target value of the electric angle is directly calculated according to the target position control quantity; the absolute position mode is suitable for the scene of known target points, such as the robot returning to the zero point.

[0074] If it is a relative position control mode, the target position control quantity and the current electric angle value are fused to calculate the absolute position target value of the electric angle. The relative position mode is suitable for incremental motion, such as the machine tool feeding X millimeters, which needs to fuse the increment and the current position to calculate the new absolute target value. The advantage of this design is to improve the flexibility and applicability of the control method, so as to cover a wider range of application scenarios.

[0075] The target position control quantity is the load end position in radian units, and the conversion formula to the electric angle unit is:

[0076]

[0077] wherein, is the electric angle position target value, is the load end target position, N is the reduction ratio, P is the motor pole pair number, and K is the electric angle resolution.

[0078] The principle of this formula is based on the physical relationship between the motor and the mechanical transmission system: the physical displacement (radian) of the load end is enlarged by the reduction ratio (N) to the mechanical angle displacement of the motor shaft, the mechanical angle of the motor shaft is converted into the electric angle through the pole pair number (P), and finally multiplied by the electric angle resolution (K) to digitize the analog electric angle into high-precision digital quantity. The value of K is usually determined by the data processing bits of the controller, such as 16 bits, which is 65536. The advantage of this formula is that all mechanical and electrical parameters that affect the final precision are taken into account, and an accurate, calculable and predictable model is given, so that the theoretical position resolution that the system can achieve can be estimated in the design stage.

[0079] The acquisition method of the electric angle integral value in step S3 includes:

[0080] If the motor is equipped with a high-precision position sensor, the initial electric angle value is obtained based on the sensor data;

[0081] If the motor is not equipped with a position sensor, the initial electric angle value is obtained through a non-inductive position estimation algorithm.

[0082] At system startup, a reliable initial electrical angle value must be obtained to start the integration process. If there is a high-precision sensor, such as an optical encoder or a magnetic encoder, it can be directly obtained, with the highest precision and the most stable startup. If not, the "non-inductive position estimation" technique is used, which is usually based on the salient pole effect of the motor or high-frequency injection method, etc., to estimate the initial position of the rotor by detecting the inductance change of the motor winding. The advantage of this acquisition method is that it clearly shows that the present invention can be used for inductive (higher performance) and non-inductive (lower cost) systems, widening the application range.

[0083] The determination of the electrical angle step value in step S5 also includes:

[0084] The single increment and maximum value of the electrical angle step value are dynamically adjusted according to the motor load state and the current limit value.

[0085] The electrical angle step value (i.e., the electrical angle planned to advance in each control period) determines the instantaneous speed and torque requirements of the motor. A large step value means that the motor needs to rotate quickly, requiring more torque. If the load is heavy or the current limit is low, a large step may cause the motor to lose step (unable to follow the instructions) or overcurrent. Therefore, the present mechanism dynamically limits the size of the step value according to the real-time load and current capacity. The advantage is that it ensures the stability and reliability of the system, preventing control failure in heavy load or insufficient power supply conditions, and is an intelligent safety buffer mechanism.

[0086] The current sampling in step S7 includes:

[0087] According to the current electrical angle value, select the phase current sampling mode, and perform Clarke transformation and Park transformation to obtain the current feedback value in the dq coordinate system.

[0088] The above steps define the standard FOC process for current sampling. Clarke transformation converts the three-phase stationary coordinate system (a, b, c) current to the two-phase stationary coordinate system (α, β). Park transformation further converts the two-phase stationary coordinate system (α, β) to the two-phase rotating coordinate system (d, q) that rotates with the rotor, where the q-axis current directly corresponds to the motor torque, and the d-axis current corresponds to the excitation component. The principle of this step is to simplify the complex AC motor control to torque (Iq) and excitation (Id) control similar to DC motors, which is the basis for achieving high-performance vector control. The advantage is that the control is decoupled, efficient, and has good torque response.

[0089] The method further includes a super-low speed motion control mode, wherein:

[0090] The speed control quantity is converted to an electrical angle step value, and the calculation formula is:

[0091]

[0092] in, This is the electrical angle step value. F is the speed control variable at the load end, and F is the vector control frequency.

[0093] In ultra-low speed motion control mode, the formula for calculating the minimum motor speed is:

[0094] .

[0095] The principle of ultra-low speed motion control mode is to transmit speed commands. Converted into electrical angle step commands for each control cycle The derivation logic of this formula is: load-side speed The speed of the motor shaft (radians / second) needs to be multiplied by the reduction ratio N. The mechanical angular velocity of the motor shaft needs to be converted into electrical angular velocity by multiplying by the number of pole pairs P. Then, it needs to be converted into electrical angle increment for each control cycle by dividing by the control frequency F. Finally, it needs to be multiplied by the resolution K to digitize it. Depend on The formula is derived by working backwards to calculate the theoretical minimum speed (i.e., the speed when each control cycle steps by one minimum electrical angle unit). Its advantages are: the speed control accuracy and stability are entirely determined by the clock and calculation accuracy of the electronic system, unaffected by traditional factors such as sensor accuracy, mechanical friction, and gear backlash. Therefore, it can achieve extremely smooth, precise, and very low rotational speeds. The theoretical minimum speed is only limited by the control frequency and electrical angle resolution, reaching a few percent of revolutions per minute or even lower.

[0096] The method also includes an exception handling mechanism:

[0097] If the detected electrical angle error exceeds the threshold, the drive current is dynamically adjusted or the electrical angle step value is limited to prevent the motor from skipping steps. With a sensor, the error of the electrical angle integral value (i.e., integral drift) can be monitored in real time via sensor feedback, and correction is performed once the error exceeds the tolerance. Without a sensor, step value limiting and current limiting are used to fundamentally prevent step loss. Its advantage lies in improving the robustness of the entire system and ensuring long-term operational reliability.

[0098] The second aspect of this invention discloses a high-precision position control system for a brushless DC motor based on electrical angle control, applicable to a high-precision position control method for a brushless DC motor based on electrical angle control, comprising:

[0099] The control data receiving module receives externally input target position control values, speed limit values, and current limit values.

[0100] The electrical angle conversion module converts the target position control quantity into an absolute position target value in the electrical angle of the motor;

[0101] An electric angle integral module is configured to obtain an integral value of a current electric angle of the motor as an absolute position feedback value.

[0102] An error calculation module is configured to calculate a difference between the absolute position target value and the absolute position feedback value to obtain a position control error.

[0103] An electric angle increment control module is configured to determine an electric angle increment of a current vector control period according to the position control error, an electric angle step limit, and a current limit value.

[0104] An electric angle updating module is configured to add the current electric angle value and the electric angle increment to update an electric angle value of a next control period.

[0105] A vector control module is configured to perform current sampling, coordinate transformation, and PID current regulation based on the updated electric angle value to generate a three-phase voltage control signal.

[0106] A drive output module is configured to output a three-phase motor drive signal through pulse width modulation to complete one vector control period.

[0107] Embodiment 1: High-precision absolute positioning control (for a precision platform);

[0108] Application scenario: a certain precision optical adjustment platform requires high positioning accuracy and controllable cost.

[0109] System parameters:

[0110] Motor pole pair number P = 4;

[0111] Reduction gear reduction ratio N = 100;

[0112] Controller electric angle resolution K = 65536 (16 bits);

[0113] Vector control frequency F = 10 kHz;

[0114] Control target: accurately rotate the load arm by 0.001°.

[0115] Implementation process:

[0116] S1: receive target position instruction θ = 0.001° ≈ 1.745e-5 rad.

[0117] S2 / S3: calculate the absolute electric angle target value using the formula:

[0118] θ_e = 1.745e-5 × (100 × 4 × 65536) / (2 × 3.1416) ≈ 72.7 (minimum electric angle units)

[0119] The current electrical angle feedback value (obtained by integration) is θ_{e_feedback}=5000.

[0120] S4: Position error Error = 72.7 - 5000 = -4927.3. The system determines that the motion is reversed.

[0121] S5: The control algorithm calculates the electrical angle increment Δθ_e=-50 (i.e. moving 50 minimum electrical angle units in the reverse direction) for the next control period according to the error size and the preset acceleration curve.

[0122] S6: Update the electrical angle setpoint: θ_e_setpoint=5000+(-50)=4950.

[0123] S7 / S8: The FOC algorithm controls the motor to generate torque to move the rotor to the position of electrical angle 4950.

[0124] Repeat S4-S8 for each control period until the error Error tends to zero.

[0125] Effect: The final positioning resolution of the load end R=360 / (100×4×65536)≈0.0137 arcseconds, which is much higher than the target value 0.001° (3.6 arcseconds), easily meeting the requirements. The entire system does not use high-cost optical encoders, but relies only on the motor's own Hall sensor for initial positioning, and then switches to the non-inductive integration mode operation.

[0126] Example 2: Ultra-low-speed smooth running (for microscope stage);

[0127] Application scenario: Biological microscope automatic scanning stage, which needs ultra-low-speed smooth motion to avoid vibration affecting observation.

[0128] System parameters:

[0129] Motor pole pairs P=4;

[0130] Reduction box reduction ratio N=120;

[0131] Electrical angle resolution K=65536;

[0132] Vector control frequency F=8kHz;

[0133] Control target: Achieve 0.02 RPM ultra-low-speed scanning of the stage.

[0134] Implementation process:

[0135] Receive speed command V_m=0.02 RPM. It needs to be converted to radians per second first: V_m=0.02×2π / 60≈0.002094 rad / s.

[0136] The required electrical angle step value is calculated using the formula:

[0137] Δθ_e = (2π x 4 x 65536 x 120) / (0.002094 x 8000) ≈ 2.36e6 / 16.752 ≈ 140,900 (units of minimum electrical angle / control period).

[0138] The single increment and maximum value of the electrical angle step value are dynamically adjusted according to the motor load state and current limit value, and the controller limits the electrical angle step value to a maximum of 1000 per period.

[0139] In practice, the system will adopt a smaller target speed or a higher control frequency. By The theoretical capacity is calculated using the formula:

[0140] V_min = (60 x 8000) / (4 x 65536 x 120) ≈ 480,000 / 31,457,280 ≈ 0.01526 RPM.

[0141] The system sets the target speed to 0.016 RPM, slightly higher than the minimum theoretical value. Recalculate the step value:

[0142] Δθ_e = (2π x 4 x 65536 x 120) / ((0.016 x 2π / 60) x 8000) = (2π x 4 x 65536 x 120) / ((0.001675) x 8000) ≈ 1.58.

[0143] That is, the electrical angle set value is increased by only about 1.58 minimum units per control period.

[0144] The system slowly and accurately updates the electrical angle set value every period, and the FOC algorithm produces a small and accurate torque to drive the motor to rotate.

[0145] Effect: The motor load end rotates extremely smoothly at a speed of 0.016 RPM, and it takes about 3750 seconds (62.5 minutes) to rotate one circle. Since speed control is essentially frequency control of electrical angle steps, its smoothness only depends on the clock accuracy of the controller, avoiding the crawling and jitter phenomenon of traditional PID at low speed, providing a disturbance-free stable environment for microscope observation.

[0146] In summary, the high-precision position control method of the direct current brushless motor based on the electric angle control converts the target position control quantity inputted from outside into an absolute position target value in units of motor electric angle, and uses the electric angle integral value as an absolute position feedback value to realize direct control of the motor position.

[0147] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as the modifications, equivalent replacements, improvements, etc. are within the spirit and principles of the present application, they should be included in the protection scope of the present application.

Claims

1. A high-precision position control method for a brushless DC motor based on electrical angle control, characterized in that, Includes the following steps: S1: Receives external input of target position control value, speed limit value, and current limit value; S2: Convert the target position control quantity into an absolute position target value in motor electrical angles; S3: Obtain the integral value of the current motor electrical angle as the absolute position feedback value; S4: Calculate the difference between the absolute position target value and the absolute position feedback value to obtain the position control error; S5: Determine the electrical angle increment of the current vector control cycle based on the position control error, electrical angle step value limit, and current limit value; S6: Add the current electrical angle value to the electrical angle increment and update it to the electrical angle value for the next control cycle; S7: Based on the updated electrical angle value, perform current sampling, coordinate transformation and PID current regulation to generate a three-phase voltage control signal; S8: Outputs a three-phase motor drive signal through pulse width modulation to complete one vector control cycle.

2. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The conversion process described in step S2 includes: If it is an absolute position control mode, the target value of the electrical angle absolute position is directly calculated based on the target position control quantity; If it is a relative position control mode, the target position control quantity is fused with the current electrical angle value to obtain the target value of the absolute electrical angle position.

3. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 2, characterized in that, The formula for converting the target position control quantity, which is the load end position in radians, to electrical degrees is as follows: in, The target value for electrical angle position. Where N is the target position at the load end, P is the reduction ratio, and K is the number of motor pole pairs.

4. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The method for obtaining the electrical angle integral value in step S3 includes: If the motor is equipped with a high-precision position sensor, the initial electrical angle value is obtained based on the sensor data; If the motor is not equipped with a position sensor, the initial electrical angle value is obtained through a sensorless position estimation algorithm.

5. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The determination of the electrical angle step value in step S5 also includes: The single increment and maximum value of the electrical angle step value are dynamically adjusted according to the motor load status and current limit value.

6. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The current sampling in step S7 includes: Select the phase current sampling mode based on the current electrical angle value, and perform Clarke and Park transformations to obtain the current feedback value in the dq coordinate system.

7. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The method also includes an ultra-low speed motion control mode, wherein: The speed control quantity is converted into an electrical angle step value, and its calculation formula is as follows: in, This is the electrical angle step value. F is the speed control variable at the load end, and F is the vector control frequency.

8. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 7, characterized in that, The formula for calculating the minimum motor speed in the ultra-low speed motion control mode is as follows: 。 9. The high-precision position control method for a brushless DC motor based on electrical angle control according to claim 1, characterized in that, The method also includes an exception handling mechanism: If the detected electrical angle error exceeds the threshold, the drive current will be dynamically adjusted or the electrical angle step value will be limited to prevent the motor from skipping steps.

10. A high-precision position control system for a brushless DC motor based on electrical angle control, applied to the high-precision position control method for a brushless DC motor based on electrical angle control as described in any one of claims 1-9, characterized in that, include: The control data receiving module receives externally input target position control values, speed limit values, and current limit values. The electrical angle conversion module converts the target position control quantity into an absolute position target value in motor electrical angles; The electrical angle integration module is used to obtain the integral value of the current motor electrical angle as the absolute position feedback value; The error calculation module is used to calculate the difference between the absolute position target value and the absolute position feedback value to obtain the position control error; The electrical angle increment control module is used to determine the electrical angle increment of the current vector control cycle based on the position control error, the electrical angle step value limit, and the current limit value. The electrical angle update module is used to add the current electrical angle value to the electrical angle increment and update it to the electrical angle value for the next control cycle. The vector control module is used to perform current sampling, coordinate transformation and PID current regulation based on the updated electrical angle value, and generate three-phase voltage control signals. The drive output module is used to output a three-phase motor drive signal through pulse width modulation to complete one vector control cycle.

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