A brushless motor electrical angle recognition method and system

Abstract

This application provides a method and system for identifying the electrical angle of a brushless motor. The method includes: establishing a simplified circuit principle model and mathematical model; transforming the brushless motor mathematical model into a brushless motor mathematical model in the Park coordinate system; deriving the steady-state electromagnetic torque mathematical model of the brushless motor; applying a micro-current to the brushless motor through an inverter and rotating it, taking its position as the relative electrical angle zero point; calculating the d-axis and q-axis components of the micro-current in the Park coordinate system; and then calculating the rotor electrical angle calibration value and the absolute electrical angle zero point. Through the above method, the absolute zero point of the brushless motor rotor can be calculated, thus determining the rotor's specific position; when the rotor's magnetic poles are exactly at the gap in the rotor's magnetic field, an external force is applied in a timely manner to drive the motor, ensuring its normal operation.

Description

Technical Field

[0001] This disclosure generally relates to the field of brushless motor electrical angle identification technology, and specifically to a brushless motor electrical angle identification method and system. Background Technology

[0002] Brushless DC motors consist of two parts, generally including an armature winding and permanent magnet poles. The armature winding is located on the stator, and the permanent magnet poles are located on the rotor. Compared to brushed motors, they eliminate the need for brushes. They feature simple structure, stable operation, high power density, and ease of maintenance, while also possessing the excellent performance of DC motors such as fast response speed and high starting torque. Brushless DC torque motors are widely used in optoelectronic equipment such as infrared search systems.

[0003] Existing brushless motors contain three coils on their rotors, requiring three-phase current to be applied. Therefore, the rotor's magnetic poles must correspond to the magnetic field generated by the armature windings on the stator. When the rotor's magnetic poles are precisely at the gaps in the rotor's magnetic field, an additional force is needed to drive the rotor to start. Therefore, determining the rotor's zero position is a key problem that needs to be solved. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a method for online identification of the electrical angle of a brushless motor.

[0005] This application provides a method for online identification of the electrical angle of a brushless motor, including:

[0006] A simplified circuit principle model of a direct brushless motor is established;

[0007] The mathematical model of the brushless motor is derived based on the simplified circuit principle model.

[0008] The brushless motor mathematical model is transformed into a brushless motor mathematical model in the Park coordinate system;

[0009] The steady-state electromagnetic torque mathematical model of the brushless motor is derived based on the mathematical model of the brushless motor in the Parker coordinate system.

[0010] By applying a micro-current to the brushless motor through the inverter, the rotor of the brushless motor is made to rotate, and the position after rotation is taken as the relative electrical angle zero position.

[0011] Calculate the d-axis component of the microcurrent relative to the Parker transform coordinate system; calculate the q-axis component of the microcurrent relative to the Parker transform coordinate system;

[0012] The rotor electrical angle calibration value is calculated based on the d-axis component, the q-axis component, and the micro-current.

[0013] The absolute electrical angle zero position is obtained by subtracting the rotor electrical angle calibration value from the relative electrical angle zero position.

[0014] According to the technical solution provided in the embodiments of this application, the mathematical model of the steady-state electromagnetic torque of the brushless motor is represented by formula (I);

[0015]

[0016] Among them, T e P is the output torque of the motor, P is the number of electrode pairs of the brushless motor, and ψ is the output torque of the motor. m For the magnetic flux linkage of the motor magnet, i d Let i be the d-axis driving current in the Parker transform coordinate system. q L is the q-axis driving current in the Parker transformed coordinate system. d L is the d-axis equivalent inductance. q This is the q-axis equivalent inductance.

[0017] According to the technical solution provided in the embodiments of this application, the d-axis component of the micro-current relative to the Parker transformation coordinate system and the q-axis component of the micro-current relative to the Parker transformation coordinate system are calculated according to formula (II);

[0018]

[0019] Among them, i d Let i be the d-axis driving current in the Parker transform coordinate system. q Let θ be the q-axis driving current in the Parker transform coordinate system, and θ be the angle between the d-axis and the α-axis.

[0020] This application, in another aspect, provides an online identification system for the electrical angle of a brushless motor, including the brushless motor electrical angle identification method as described in claim 1, and further comprising:

[0021] Embedded software is used to determine the electrical angle and drive the brushless motor to rotate; the specific determination process of the embedded software includes:

[0022] S4.1: Obtain the electrical angle position information of the brushless motor rotor, wherein the electrical angle position information includes: the d-axis component and the q-axis component;

[0023] S4.2: Judgment: If the brushless motor rotor is at the absolute electrical angle zero position, proceed directly to S4.6; otherwise, proceed to the next step.

[0024] S4.3: Online identification function for the relative electrical angle zero position of the brushless motor;

[0025] S4.4: Use an inverter to apply a micro-current to the rotor of the brushless motor to drive the brushless motor to rotate to the relative electrical angle zero position; and calculate the rotor electrical angle calibration value;

[0026] S4.5: Determination: If the brushless motor rotor is at the absolute electrical angle zero position, proceed to the next step; otherwise, return to S4.4.

[0027] S4.6: Switch to absolute electrical angle zero and drive the brushless motor to rotate.

[0028] According to the technical solution provided in the embodiments of this application, multiple rotor electrical angle calibration values ​​are obtained by performing multiple calculations using the embedded software and then averaging them to obtain the average rotor electrical angle calibration value; then, the absolute electrical angle zero position is calculated based on the average rotor electrical angle calibration value.

[0029] According to the technical solution provided in the embodiments of this application, an incremental encoder is used to drive the brushless motor rotor to start; after the brushless motor rotor starts, it switches to a conventional drive device to drive the brushless motor rotor to rotate continuously.

[0030] The beneficial effects of this application are as follows:

[0031] A simplified circuit principle model and mathematical model are established, transforming the brushless motor mathematical model into a brushless motor mathematical model in the Park coordinate system. A steady-state electromagnetic torque mathematical model for the brushless motor is derived. A micro-current is applied to the brushless motor via an inverter, causing it to rotate, and its position is taken as the relative electrical angle zero point. The d-axis and q-axis components of the micro-current in the Park coordinate system are calculated respectively. Furthermore, the rotor electrical angle calibration value and absolute electrical angle zero point are calculated. Through the above method, the absolute zero point of the brushless motor rotor can be calculated, thus determining the rotor's specific position. When the rotor's magnetic poles are exactly at the gap in the rotor's magnetic field, an external force is applied in a timely manner to drive the motor, ensuring its normal operation. Attached Figure Description

[0032] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the structure of an online identification method for the electrical angle of a brushless motor provided in this application;

[0034] Figure 2 This is a schematic diagram of the structure of an online electrical angle identification system for a brushless motor provided in this application;

[0035] Figure 3 Simplified circuit diagram of a brushless motor

[0036] Figure 4 The equivalent d-axis circuit model diagram of a brushless motor;

[0037] Figure 5This is the equivalent q-axis circuit model diagram of a brushless motor. Detailed Implementation

[0038] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] Please refer to Figure 1 , Figure 3 and Figure 4 This is a schematic diagram of an online electrical angle identification method for a brushless motor provided in this embodiment, including:

[0042] S1: Establish a simplified circuit principle model for a direct brushless motor;

[0043] S2: The mathematical model of the brushless motor is derived based on the simplified circuit principle model.

[0044] S3: Transform the brushless motor mathematical model into a brushless motor mathematical model in the Park coordinate system;

[0045] S4: Based on the mathematical model of the brushless motor in the Parker coordinate system, the mathematical model of the steady-state electromagnetic torque of the brushless motor is derived.

[0046] S5: Apply a micro-current to the brushless motor through the inverter to make the brushless motor rotor rotate, and take the position after rotation as the relative electrical angle zero position.

[0047] S6: Calculate the d-axis component of the micro-current relative to the Parker transform coordinate system; calculate the q-axis component of the micro-current relative to the Parker transform coordinate system;

[0048] S7: The rotor electrical angle calibration value is calculated based on the d-axis component, the q-axis component, and the micro-current.

[0049] S8: Obtain the absolute electrical angle zero position by subtracting the rotor electrical angle calibration value from the relative electrical angle zero position.

[0050] In some implementations, the rotor electrical angle calibration value is related to the input micro-current. The magnitude of the rotor electrical angle calibration value is controlled by adjusting the micro-current, generally ensuring that the rotor electrical angle calibration value is no greater than 10 degrees.

[0051] In some implementations... Figure 3 Terminals A, B, and C are connected to the three-phase current respectively, and M represents a brushless motor.

[0052] In some implementations... Figure 4 and Figure 5 In this diagram, Ud represents the equivalent power source along the d-axis, R represents the equivalent resistance, id represents the current component along the d-axis, Ld represents the equivalent inductance along the d-axis, ω represents the electrical angle, and ψ represents the equivalent current component along the d-axis. d The d-axis component represents the magnetic flux linkage of the motor magnet. Uq represents the equivalent power supply along the q-axis, iq represents the current component along the q-axis, Lq represents the equivalent inductance along the q-axis, and ψ... q This represents the q-axis component of the magnetic flux linkage of the motor magnet.

[0053] Specific calculation and derivation process: Formula (I) is derived from formulas (III) and (IV);

[0054]

[0055]

[0056] Among them, u d For the d-axis voltage, u q i is the q-axis voltage; d i is the d-axis current; q U is the q-axis current; u0 is the zero-sequence voltage; i0 is the zero-sequence current; L d For d-axis inductance; L q R is the q-axis inductance. s ω is the stator phase resistance; e ψ is the rotor's electric angular velocity. f is the flux linkage of the rotor fundamental excitation through the stator winding; p is the differential operator.

[0057] Furthermore, the mathematical model of the steady-state electromagnetic torque of the brushless motor is represented by formula (I);

[0058]

[0059] Among them, T e P is the output torque of the motor, P is the number of electrode pairs of the brushless motor, and ψ is the output torque of the motor. m For the magnetic flux linkage of the motor magnet, i d Let i be the d-axis driving current in the Parker transform coordinate system. q L is the q-axis driving current in the Parker transformed coordinate system. d L is the d-axis equivalent inductance. q This is the q-axis equivalent inductance.

[0060] Furthermore, the d-axis component and the q-axis component of the micro-current in the Parker transformation coordinate system are calculated according to formula (II).

[0061]

[0062] Among them, i d Let i be the d-axis driving current in the Parker transform coordinate system. q Let θ be the q-axis driving current in the Parker transform coordinate system, and θ be the angle between the d-axis and the α-axis.

[0063] Specifically, the angle θ between the d-axis and the α-axis is the rotor electrical angle calibration value.

[0064] Specifically, mathematically speaking, the Park transformation transforms the abc coordinate system to the dq0 coordinate system, transforming ua, ub, uc, ia, ib, ic, magnetic linkage a, magnetic linkage b, and magnetic linkage c into the dq0 coordinate system; the reverse is the inverse Park transformation.

[0065] From a physical perspective, the Park transformation projects the currents ia, ib, and ic onto the α and β axes, respectively, and onto the d and q axes, thus representing the stator currents onto the direct and quadrature axes. For steady-state conditions, after this transformation, iq and id remain constant, facilitating calculations.

[0066] Example 2

[0067] Please refer to Figure 2 This is a schematic diagram of an online electrical angle identification system for a brushless motor provided in this embodiment, which includes the brushless motor electrical angle identification method as described in claim 1, and further includes:

[0068] Embedded software is used to determine the electrical angle and drive the brushless motor to rotate; the specific determination process of the embedded software includes:

[0069] S4.1: Obtain the electrical angle position information of the brushless motor rotor, wherein the electrical angle position information includes: the d-axis component and the q-axis component;

[0070] S4.2: Judgment: If the brushless motor rotor is at the absolute electrical angle zero position, proceed directly to S4.6; otherwise, proceed to the next step.

[0071] S4.3: Online identification function for the relative electrical angle zero position of the brushless motor;

[0072] S4.4: Use an inverter to apply a micro-current to the rotor of the brushless motor to drive the brushless motor to rotate to the relative electrical angle zero position; and calculate the rotor electrical angle calibration value;

[0073] S4.5: Determination: If the brushless motor rotor is at the absolute electrical angle zero position, proceed to the next step; otherwise, return to S4.4.

[0074] S4.6: Switch to absolute electrical angle zero and drive the brushless motor to rotate.

[0075] In some implementations, the relative electrical angle zero-position online identification function includes formula (I) and formula (II), as well as the entire process of deriving the formulas.

[0076] Specifically, by using embedded software to calculate and derive the absolute electrical angle zero position of the brushless motor rotor, it is possible to quickly find zero and maximize the driving efficiency of the brushless motor.

[0077] Furthermore, multiple calculations are performed using the embedded software to obtain multiple rotor electrical angle calibration values, and the average value is taken to obtain the average rotor electrical angle calibration value; then, the absolute electrical angle zero position is calculated based on the average rotor electrical angle calibration value.

[0078] In some implementations, the absolute electrical angle zero point is calculated by averaging multiple calculations using the embedded software. This avoids single-shot errors that could lead to failure in zero finding and improves the accuracy of the zero finding results.

[0079] Furthermore, an incremental encoder is used to drive the brushless motor rotor to start; after the brushless motor rotor starts, it switches to a conventional drive device to drive the brushless motor rotor to rotate continuously.

[0080] In some implementations, an incremental encoder is used to start the brushless motor rotor, and then a conventional drive device is switched to keep the brushless motor rotor rotating. The incremental encoder can use the initial position of the brushless motor rotor as the zero position to start the brushless motor rotor to start rotating. After the brushless motor rotor starts rotating, it can be calculated to convert the initial position to the absolute zero position, ultimately achieving the zero-finding effect.

[0081] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for identifying the electrical angle of a brushless motor, characterized in that, include: Establish a simplified circuit principle model for a brushless motor; The mathematical model of the brushless motor is derived based on the simplified circuit principle model. The brushless motor mathematical model is transformed into a brushless motor mathematical model in the Park coordinate system; The steady-state electromagnetic torque mathematical model of the brushless motor is derived based on the mathematical model of the brushless motor in the Parker coordinate system. By applying a micro-current to the brushless motor through the inverter, the rotor of the brushless motor is made to rotate, and the position after rotation is taken as the relative electrical angle zero position. Calculate the microcurrent in the Park transform coordinate system. Axial components and Axial components; According to the above Axis component, the The rotor electrical angle calibration value is calculated from the shaft component and the micro-current. The absolute electrical angle zero position is obtained by subtracting the rotor electrical angle calibration value from the relative electrical angle zero position.

2. The brushless motor electrical angle identification method according to claim 1, characterized in that, The mathematical model of the steady-state electromagnetic torque of the brushless motor is expressed by formula (I): (one); in, For the motor output torque, This represents the number of electrode pairs in a brushless motor. For the magnetic flux of the motor magnet, In the Park transform coordinate system Shaft drive current, In the Park transform coordinate system Shaft drive current, for Shaft equivalent inductance, for Shaft equivalent inductance.

3. The brushless motor electrical angle identification method according to claim 1, characterized in that, The micro-current relative to the Parker transform coordinate system The axis components and the micro-current relative to the Park transform coordinate system The shaft components are calculated according to formula (II); (two); in, In the Park transform coordinate system Shaft drive current, In the Park transform coordinate system Shaft drive current, for shaft and The angle between axes.

4. A brushless motor electrical angle identification system, characterized in that, A method for performing an electrical angle identification of a brushless motor as described in claim 1 includes: Embedded software is used to determine the electrical angle and drive the brushless motor to rotate; the specific determination process of the embedded software includes: S4.1: Obtain the electrical angle position information of the brushless motor rotor, the electrical angle position information including: Axis component, the Axial components; S4.2: Judgment: If the brushless motor rotor is at the absolute electrical angle zero position, proceed directly to S4.6; otherwise, proceed to the next step. S4.3: Online identification function for the relative electrical angle zero position of the brushless motor; S4.4: Use an inverter to apply a micro-current to the rotor of the brushless motor to drive the brushless motor to rotate to the relative electrical angle zero position; and calculate the rotor electrical angle calibration value; S4.5: Determine: If the brushless motor rotor is at the absolute electrical angle zero position, proceed to the next step; otherwise, return to S4.

4. S4.6: Switch to the absolute electrical angle zero position and drive the brushless motor to rotate.

5. The brushless motor electrical angle identification system according to claim 4, characterized in that, Multiple rotor electrical angle calibration values ​​are obtained by performing multiple calculations using the embedded software and then averaging them to obtain the average rotor electrical angle calibration value; then, the absolute electrical angle zero position is calculated based on the average rotor electrical angle calibration value.

6. The brushless motor electrical angle identification system according to claim 4, characterized in that, An incremental encoder is used to drive the brushless motor rotor to start; after the brushless motor rotor starts, it switches to a conventional drive device to drive the brushless motor rotor to rotate continuously.

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