Rotor Initial Position Detection Method Based on Fixed Virtual Axis High-Frequency Pulse-Excited Square-Wave Injection

Abstract

The present invention discloses a method for detecting the initial rotor position by injecting a pulsating square wave with a fixed virtual axis at high frequency, which includes a high-frequency pulsating square wave injection module, an electrical angle adjustment module of the motor, a detection module, and an interval judgment module. A pulsating square wave high-frequency voltage signal is injected into the d'-axis in the virtual rotating coordinate system. The amplitude and frequency of the injected high-frequency voltage signal depend on the motor, and the injected voltage on the q'-axis is 0. The present invention utilizes the saturation salient pole effect of the motor to detect the rotor position of a non-salient pole motor, and there is no filtering, no adjustable parameters, and no complex calculation process. The injection of the high-frequency signal causes the rotor to generate a response current, and the response current values corresponding to different positions of the rotor are different. Therefore, the response current also contains the position information of the rotor. Further, according to the interval judgment, the interval where the rotor electrical angle is located is reduced, and finally, the unique electrical angle information is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of rotor initial position detection, and specifically to a rotor initial position detection method by injecting a high-frequency pulsating square wave on a fixed virtual axis. Background Art

[0002] Due to advantages such as simple structure, convenient operation, high reliability, and easy control, permanent magnet synchronous motors have been widely used in servo drive systems. Especially in fields such as industrial robotic arms, aerospace, and numerically controlled machine tools where high requirements are placed on motor performance and control accuracy, permanent magnet synchronous motors can be divided into surface-mounted and interior-mounted types. Most surface-mounted permanent magnet synchronous motors are non-salient pole motors and are not suitable for detecting the rotor initial position by the method of injecting high-frequency signals without sensors for field-oriented control (FOC).

[0003] This patent proposes a method for detecting the rotor initial position of a surface-mounted permanent magnet synchronous motor. The surface-mounted permanent magnet synchronous motor does not have a salient pole effect. This method utilizes the saturated salient pole effect of the motor. When the virtual axis is positioned at each angle, the magnitude of the response current is detected by injecting positive and negative square wave high-frequency voltage signals. Different response currents will be detected at different electrical angles. Therefore, the magnitude of the response current contains the initial position information. This method does not require any filters or phase-locked loops, nor does it involve excessive formula derivation. The implementation process of the method is simple and is applicable to both salient pole and non-salient pole motors. Summary of the Invention

[0004] The purpose of the present invention is to provide a rotor initial position detection method by injecting a high-frequency pulsating square wave on a fixed virtual axis, and to solve the technical problems raised in the above background art through the high-frequency pulsating square wave voltage injection method.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A rotor initial position detection method by injecting a high-frequency pulsating square wave on a fixed virtual axis, including a high-frequency pulsating square wave injection module, an electrical angle adjustment module of the motor, a detection module, and an interval judgment module. A pulsating square wave high-frequency voltage signal is injected on the d'-axis in the virtual rotating coordinate system. The amplitude and frequency of the injected high-frequency voltage signal depend on the motor, and the injected voltage on the q'-axis is 0;

[0006]

[0007] Wherein U q , U d are the voltage signals on the q-axis and d-axis respectively. n determines the injection frequency, and U m is the amplitude of the injected signal.

[0008] Preferably, the α-β is two stationary coordinate systems, d-q is called the rotating coordinate system, and d'-q' is the virtual rotating coordinate system. Let the angle between the α-axis of the two stationary coordinate systems and the d'-axis of the virtual rotating coordinate system be θ'. The direction of the rotor N pole is the direction of the d-axis of the rotating coordinate system, and the electrical angle of the motor is θ, that is, the angle between the α-axis and the d-axis. The mechanical angle is represented by θ 1 θ 1 = θ / p, where p is the number of pole pairs. Rotate the motor and adjust the electrical angle θ of the motor to 0.

[0009] Preferably, set the initial angle θ' = 0, collect the d-axis current at this time, rotate the included angle θ' counterclockwise by 30°, collect the d-axis current once until the virtual axis rotates one week, and end the sampling when θ' = 330°.

[0010] Preferably, change the electrical angle θ of the motor, rotate it counterclockwise by 30°, repeat the steps of claim 3, rotate the virtual axis counterclockwise one week, and perform current sampling every 30° until the current sampling ends when the electrical angle rotates one week θ = 330°.

[0011] Preferably, sort out the collected current samples, find the set of data with the largest change in current sampling at different mechanical angles under each virtual angle θ', and the virtual angle at this time is the optimal virtual angle θ'.

[0012] Preferably, set θ' as the angle required for the park transformation and the inverse park transformation.

[0013] Preferably, change the θ of the motor while θ' remains unchanged 1 , perform current detection every 30°, collect the i d value, and obtain the corresponding relationship between the electrical angle θ and i d .

[0014] Preferably, although the N pole of the motor rotor is not necessarily completely consistent with the stator winding direction, it must be in a certain winding axis area. Therefore, pulse signals with equal width and opposite directions are applied to the three windings respectively. The set of winding directions with the largest response current collected is the rotor pointing area. It can be judged that the rotor electrical angle θ can be reduced to 0°-60°, and combined with the high-frequency pulsating square wave injection for determining the virtual axis in the front, the unique electrical angle θ can be obtained.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The present invention utilizes the saturation salient-pole effect of the motor to detect the rotor position of a non-salient-pole motor, without filtering, adjustable parameters, or complex calculation processes. High-frequency signal injection causes the rotor to generate a response current, and the response current values corresponding to different rotor positions are different. Therefore, the response current also contains the rotor position information. Further, the interval where the rotor electrical angle is located is reduced based on interval judgment, and finally, the unique electrical angle information is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a system flowchart of the present invention;

[0018] Figure 2 is a relationship diagram of the three coordinate axes of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Please refer to FIG. 1 and Figure 2, an embodiment provided by the present invention: a method for detecting the initial position of the rotor by injecting a pulsating square wave with a fixed virtual axis at high frequency, including a high-frequency pulsating square wave injection module, an electrical angle adjustment module of the motor, a detection module, and an interval judgment module. A pulsating square wave high-frequency voltage signal is injected into the d'-axis of the virtual rotating coordinate system. The amplitude and frequency of the injected high-frequency voltage signal depend on the motor, and the injected voltage on the q'-axis is 0;

[0023]

[0024] where U q , U d are the voltage signals on the q-axis and d-axis respectively. n determines the injection frequency, and U m is the amplitude of the injected signal. Through the setting of the high-frequency pulsating square wave injection module, the pulsating square wave high-frequency voltage signal is injected into the d'-axis of the virtual rotating coordinate system;

[0025] Please refer to 1 and Figure 2 , α-β is a two-phase stationary coordinate system, d-q is called a rotating coordinate system, and d'-q' is a virtual rotating coordinate system. Let the angle between the α-axis of the two-phase stationary coordinate system and the d'-axis of the virtual rotating coordinate system be θ'. The direction pointed by the N pole of the rotor is the direction of the d-axis of the rotating coordinate system. The electrical angle of the motor is θ, that is, the angle between the α-axis and the d-axis. The mechanical angle is represented by θ 1 , θ 1 =θ / p, where p is the number of pole pairs. Rotate the motor and adjust the electrical angle θ of the motor to 0. Set the initial angle θ' = 0, collect the current on the d-axis at this time, rotate the included angle θ' counterclockwise by 30°, collect the current on the d-axis once, until the virtual axis rotates one week, and the sampling ends when θ' = 330°. Change the electrical angle θ of the motor, rotate it counterclockwise by 30°, repeat the steps of claim 3, rotate the virtual axis counterclockwise for one week, and perform current sampling every 30°, until the current sampling ends when the electrical angle rotates one week θ = 330°. Organize the collected current samples, and find the set of data with the largest change in current sampling at different mechanical angles under each virtual angle θ'. At this time, the virtual angle is the optimal virtual angle θ'. Through the setting of the electrical angle adjustment module of the motor, adjust θ to 0, rotate the d'-axis counterclockwise, and detect the i d value every 30°. Then rotate the d-axis counterclockwise, and also detect the i d value every 30°. Organize the data, and then it is possible to obtain the set of data with the largest change in current sampling at different electrical angles under each θ', and further select the optimal virtual angle θ';

[0026] Please refer to 1 and Figure 2 , set θ' as the angle required for the park transformation and the inverse park transformation. Without changing θ', change the θ 1 of the motor, perform current detection every 30°, and collect id value, the electrical angle θ and i are obtained d corresponding relationship. Through the setting of the detection module, the response current values corresponding to different true angles of the motor rotor can be detected;

[0027] Please refer to 1 and Figure 2 , since the different angles of the motor rotor and the response current values are not in a one-to-one correspondence, because each electrical angle θ corresponds to an i d value, but one i d value corresponds to multiple electrical angles θ, so interval judgment is required to make the i d value in each interval have a one-to-one correspondence with the electrical angle θ. Although the N pole of the motor rotor is not necessarily completely consistent with the stator winding direction, it must be in a certain winding axis region. Therefore, pulse signals with equal width and opposite directions are applied to the three windings respectively, and the winding direction of the group with the largest response current collected is the rotor pointing region. It can be judged that the rotor electrical angle θ can be reduced to 0°-60°. Combining with the previous fixed virtual axis high-frequency pulsating square wave injection, the unique electrical angle θ can be obtained. Through the setting of the interval judgment module, pulse signals with equal width and opposite directions are applied to the three windings respectively, and the winding direction of the group with the largest response current collected is the rotor pointing region, and the unique electrical angle θ is obtained through the interval judgment module.

[0028] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A method for detecting the initial position of a rotor by injecting a high-frequency pulsating square wave on a fixed virtual axis, which includes a high-frequency pulsating square wave injection module, an electrical angle adjustment module of the motor, a detection module, and an interval judgment module. It is characterized in that: The high-frequency pulsating square wave injection module is used to inject a pulsating square wave high-frequency voltage signal into the d'-axis of the virtual rotating coordinate system. The amplitude and frequency of the injected high-frequency voltage signal depend on the motor, and the injected voltage on the q'-axis is 0. ； where U q and U d are the voltage signals on the q-axis and d-axis respectively, n determines the injection frequency, and U m is the amplitude of the injection signal; α-β are two static coordinate systems, d-q is called the rotating coordinate system, and d'-q' is the virtual rotating coordinate system. Among them, the angle between the α-axis of the two static coordinate systems and the d'-axis of the virtual rotating coordinate system is the virtual angle θ'. The direction pointed by the rotor N pole is the direction of the d-axis of the rotating coordinate system, and the electrical angle of the motor is θ, that is, the angle between the α-axis and the d-axis. The mechanical angle is represented by θ 1 denotes, θ 1 = θ / p, where p is the number of pole pairs. Rotate the motor and adjust the electrical angle θ of the motor to 0. The electrical angle adjustment module of the motor can adjust the electrical angle of the motor and perform a detection every 30°; Change the electrical angle θ of the motor, rotate it counterclockwise by 30°, rotate the virtual axis counterclockwise for one week, and perform current sampling every 30° until the current sampling ends when the electrical angle rotates one week, θ = 330°. Sort out the collected current samples, find the group of data with the largest change in current sampling at different mechanical angles under each virtual angle θ'. At this time, the virtual angle is the optimal virtual angle θ'. Continuously change the electrical angle θ of the motor through the electrical angle adjustment module of the motor, perform detection every 30° adjustment, and when the current angle of the electrical angle θ of the motor is reached, rotate the virtual axis for one week, and collect the d-axis current every 30° adjustment. After sorting out the collected current samples, the optimal virtual angle θ' can be obtained. Set θ' as the angle required for park transformation and inverse park transformation. Change the θ of the motor while keeping θ' unchanged 1 , perform current detection every 30°, and collect i d values to obtain the corresponding relationship between the electrical angle θ and i d . The detection module is used to detect the θ of the motor when θ' remains unchanged 1 The i value every 30° d is compared to obtain the corresponding relationship between the electrical angle θ and i d ; Although the N pole of the motor rotor is not necessarily completely consistent with the stator winding direction, it must be in a certain winding axis region. Therefore, pulse signals with equal width and opposite directions are applied to the three windings respectively. The winding direction of the group with the largest response current collected is the rotor pointing region. It is judged that the electrical angle θ of the rotor can be reduced to 0° - 60°. Combining the high-frequency pulsating square wave injection on the fixed virtual axis in the front, the unique electrical angle θ can be obtained. The interval judgment module is used to judge that after applying pulse signals with equal width and opposite directions to the three windings respectively, the winding direction of the winding with the largest response current is the rotor pointing region. At this time, the range of the electrical angle θ of the rotor can be reduced to 0° - 60° through the interval judgment module. According to the method of injecting a high-frequency pulsating square wave on the fixed virtual axis, the specific value of the unique electrical angle θ can be judged.

2. The method for detecting the initial position of a rotor by injecting a high-frequency pulsating square wave on a fixed virtual axis according to claim 1. It is characterized in that: Set the initial angle of the virtual angle θ' = 0, collect the d-axis current at this time, rotate θ' counterclockwise by 30°, and collect the d-axis current once until the virtual axis rotates one week and the sampling ends when θ' = 330°.

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