Start control method and system for permanent magnet synchronous motor

Abstract

The invention discloses a starting control method and system for a permanent magnet synchronous motor, and the method comprises the steps: defining an initial position in an open-loop state, positioning a rotor winding at the initial position, and recording a first electrical angle difference between an open-loop given coordinate system and an actual coordinate system; analyzing the change state of the first electrical angle difference, adding a starting current to the motor, and switching the motor from an open-loop state to a closed-loop state until the motor accelerates to reach a target rotating speed; current regulation is carried out on the motor, so that the q-axis current of the motor is kept unchanged under the condition that the second electrical angle difference of the closed-loop given coordinate system relative to the actual coordinate system is reduced to zero; and when the d-axis current of the motor is reduced to 0, starting is completed. Smooth switching from an I / F open-loop state to a closed-loop state is realized, and impact of current and rotating speed is reduced.

Description

Technical Field

[0001] The present invention relates to the field of PMSM starting technology, and in particular to a starting control method and system for a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motor (PMSM) has the characteristics of simple structure, high power density, strong overload capacity and easy maintenance. It has been widely used in industrial robots, electric vehicles, aerospace and other fields.

[0003] During the startup of a permanent magnet synchronous motor, the motor's back electromotive force is low, which makes it difficult for the sensorless control algorithm based on the back electromotive force to accurately estimate the position and speed of the rotor. Therefore, high-frequency injection, V / F control, I / F control and other methods are usually used as alternatives until the motor reaches a certain speed, and then switch to sensorless control based on back electromotive force.

[0004] However, in order to achieve rapid start-up of the motor in the prior art, the slope of the current drop needs to be as large as possible, but this will have a large impact on the current and speed, resulting in system instability and the risk of the motor losing step. Summary of the invention

[0005] The purpose of the present invention is to provide a simple solution that can achieve smooth switching from an open-loop state to a closed-loop state without causing a large impact on the current and the rotation speed.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a starting control method for a permanent magnet synchronous motor, including: defining an initial position in an open-loop state and positioning the rotor winding at the initial position, recording a first electrical angle difference between the open-loop given coordinate system and the actual coordinate system; analyzing the changing state of the first electrical angle difference, and adding a starting current to the motor until the motor accelerates to reach the target speed, and then switching the motor from an open-loop state to a closed-loop state; regulating the motor current so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero; and completing the startup when the d-axis current of the motor drops to 0.

[0007] Preferably, in the step of defining the initial position in the open-loop state and positioning the rotor winding at the initial position, and recording the first electrical angle difference between the open-loop given coordinate system and the actual coordinate system, it includes: in the open-loop state, controlling the rotation direction and the initial position of the rotor by controlling the magnitude and direction of the DC voltage applied to the stator winding, so that the initial position in the open-loop state lags behind the initial position of the rotor actual coordinate system by 90°; and recording the first electrical angle difference that characterizes the electrical angle deviation between the rotor position in the open-loop state and the actual rotor position.

[0008] Preferably, the first electrical angle difference is calculated using the following expression:

[0009] △θ1=θ-θ *

[0010] ω * =∫Δωdt

[0011] θ * =∫ω * dt

[0012] Among them, △θ1 represents the first electrical angle difference, θ represents the electrical angle of the rotor in the actual coordinate system, and θ * Represents the electrical angle in the open-loop given coordinate system, ω * represents the angular velocity in the open-loop given coordinate system, △ω represents the angular acceleration in the open-loop given coordinate system, and t represents time.

[0013] Preferably, the step of analyzing the changing state of the first electrical angle difference and adding a starting current to the motor includes: adding a starting current to the motor according to the changing trend of the first electrical angle difference so that the rotor speed increases from 0 to a target speed, wherein the target speed is determined based on the difference between the electromagnetic torque of the motor and the load torque.

[0014] Preferably, the rising state of the rotor speed is determined using the following expression:

[0015]

[0016] Among them, T e Represents electromagnetic torque, n p represents the number of pole pairs, i q represents the q-axis current in the actual coordinate system, ψ i represents the stator flux, θ represents the electrical angle of the rotor in the actual coordinate system, ω represents the angular velocity in the actual coordinate system, T L represents the load torque, J represents the moment of inertia of the rotor, and t represents time.

[0017] Preferably, the step of switching the motor from an open-loop state to a closed-loop state also includes: performing a coordinate transformation on the electrical angle before switching to ensure that the electrical angle of the motor remains unchanged before and after the switching, including: at the same time when the open-loop operation is switched to the closed-loop operation, the closed-loop given coordinate system is instantly aligned with the open-loop given coordinate system, and the rotor position in the closed-loop given coordinate system is equal to the rotor position in the open-loop given coordinate system, and at the same time, the rotor position in the closed-loop given coordinate system after the assignment is Park transformed.

[0018] Preferably, in the step of regulating the motor current so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero, the step includes: when the second electrical angle difference is set to zero, projecting the current component in the closed-loop given coordinate system to the actual coordinate system to ensure that the q-axis current component value in the actual coordinate system remains unchanged during the switching process, and projecting the integral value of the PI controller on the current loop in the closed-loop given coordinate system to the actual coordinate system to ensure that the integral value of the PI controller in the actual coordinate system remains unchanged during the switching process.

[0019] Preferably, the q-axis and d-axis components are projected using the following expressions:

[0020] A=A′cos△θ2

[0021] B=B′sin△θ2

[0022] Among them, △θ2 represents the second electrical angle difference, A represents the q-axis component of the parameter to be projected in the actual coordinate system, A′ represents the q′-axis component of the parameter to be projected in the closed-loop given coordinate system, B represents the d-axis component of the parameter to be projected in the actual coordinate system, and B′ represents the d′-axis component of the parameter to be projected in the closed-loop given coordinate system.

[0023] On the other hand, an embodiment of the present invention provides a computer-readable storage medium, characterized in that it contains a series of instructions for executing the method steps described above.

[0024] In addition, an embodiment of the present invention also provides a starting control system for a permanent magnet synchronous motor, including: an open-loop state data acquisition module, which is configured to define the initial position in the open-loop state and position the rotor winding at the initial position, and record the first electrical angle difference between the open-loop given coordinate system and the actual coordinate system; a state switching control module, which is configured to analyze the changing state of the first electrical angle difference, and add a starting current to the motor until the motor accelerates to reach the target speed, and then switches the motor from the open-loop state to the closed-loop state; a closed-loop control module, which is configured to regulate the current of the motor so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero; a starting completion module, which is configured to complete the starting when the d-axis current of the motor drops to 0.

[0025] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0026] The present invention proposes a new I / F starting method for permanent magnet synchronous motor based on smooth switching strategy. The present invention first switches to the closed loop state and ensures that the angle remains unchanged before and after the switching, so as to achieve smooth switching between the open loop state and the closed loop state. Secondly, the current is adjusted by setting the electrical angle difference to 0 and projecting to ensure that the q-axis current value and the current loop integral remain unchanged before and after the switching, thereby reducing the current and speed impact. Finally, the d-axis current value is slowly reduced to 0 to achieve i d = 0. Compared with other methods, the algorithm of the present invention is simpler, and the smooth switching from the I / F open-loop state to the closed-loop state is achieved by first switching to the closed-loop state and then adjusting the current, thereby reducing the impact of the current and the speed.

[0027] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 Schematic diagram of the overall steps of the startup control method for a permanent magnet synchronous motor according to an embodiment of the present application.

[0030] Figure 2 Schematic diagram of coordinate system switching steps in a startup control method for a permanent magnet synchronous motor according to an embodiment of the present application.

[0031] Figure 3A schematic diagram of the implementation principle of the startup control method for a permanent magnet synchronous motor according to an embodiment of the present application.

[0032] Figure 4 It is a structural schematic diagram of a starting control system for a permanent magnet synchronous motor according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0034] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be performed in a sequence different from that here.

[0035] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0036] In order to solve the problems in the above-mentioned background technology, the embodiment of the present application proposes a new I / F starting method for a permanent magnet synchronous motor based on a smooth switching strategy. The method includes: in an open-loop state, positioning the rotor to the initial position, obtaining the electrical angle difference, and adding the starting current to increase the speed; when accelerating to the target speed, switching to a closed-loop state, at the switching moment, using the electrical angle before the switching to perform coordinate transformation to ensure that the angle remains unchanged before and after the switching; reducing the electrical angle difference to 0, while adjusting the current, projecting the current target value in a given coordinate system and the integral in the current loop to the actual coordinate system to ensure that the axis current value remains unchanged before and after the switching; slowly reducing the d-axis current to 0 to complete the startup. The present invention realizes the smooth switching from I / F open-loop control to closed-loop control, which not only improves the stability of the system, but also reduces the impact of current and speed.

[0037] Figure 3 Schematic diagram of the implementation principle of the startup control method for a permanent magnet synchronous motor according to an embodiment of the present application. Figure 3, the working principle of the original PMSM controller is explained. In the actual control process, the outer loop is the speed loop, which uses the detected speed ω as feedback; the inner loop is the current loop, which uses current sampling to obtain the stator three-phase current i a 、i b and i c , and then through Clark transformation and Park transformation, the stator current i in the dq synchronous reference frame is obtained d and i q As feedback. Given speed ω * The given value of the q-axis stator current is obtained by subtracting the actual speed ω through the PI controller. The d-axis current given value is 0. The given values ​​of the two current components and the measured value i q 、i d After the difference is made, the stator voltage u in the dq synchronous reference system is obtained through the PI controller. d * and u q * , the two are transformed by Park inverse transformation to obtain the stator voltage u in the αβ coordinate system α and u β , which is input into SVPWM to obtain the three-phase duty cycle signal, and controls the on and off of the inverter switch tube, thereby realizing the control of PMSM.

[0038] Figure 1 Schematic diagram of the overall steps of the startup control method for a permanent magnet synchronous motor according to an embodiment of the present application. Figure 1 The specific steps and implementation principles of the motor starting control method described in the embodiment of the present invention are explained.

[0039] like Figure 1 As shown, in step S110, an initial position in an open-loop state is defined and the rotor winding is positioned at the initial position, thereby recording a first electrical angle difference between the open-loop given coordinate system and the actual coordinate system.

[0040] In step S110, in the open-loop state, the rotation direction and initial position of the rotor are controlled by controlling the magnitude and direction of the DC voltage applied to the stator winding, so that the initial position in the open-loop state lags behind the initial position of the actual rotor coordinate system by 90°. At the same time, the first electrical angle difference representing the electrical angle deviation between the rotor position in the open-loop state and the actual rotor position is recorded.

[0041] Specifically, first, a sufficiently large DC voltage is passed through the stator winding in the open loop state to position the rotor to a given initial position, and the electrical angle difference between the actual rotor position and the given rotor position is calculated, see Figure 2 (a) In Figure 2 middle, I qs Represents the component of the stator current on the q-axis.

[0042] Define the open loop given coordinate system as d * q * Coordinate system, the actual coordinate system of the rotor is the dq coordinate system, and the first electrical angle difference between the two-phase coordinate systems is:

[0043] △θ1=θ-θ * (1)

[0044] Wherein, △θ1 represents the first electrical angle difference; θ represents the electrical angle of the rotor in the actual coordinate system (i.e., the actual rotor position); θ * It represents the electrical angle in the open-loop given coordinate system, that is, the rotor position given by the open-loop position generator.

[0045] In actual application, by controlling the magnitude and direction of the DC voltage applied to the stator winding, the magnetic flux distribution in the air gap is accurately controlled, and then the rotation direction and initial position of the rotor are controlled, so that d * q * The initial position of the coordinate system (ie, the open-loop given coordinate system) lags behind the initial position of the dq coordinate system (ie, the actual rotor coordinate system) by 90°.

[0046] Among them, the speed provided by the open-loop position generator, that is, the angular acceleration in the given coordinate system of the loop is:

[0047] ω * =∫Δωdt (2)

[0048] Among them, ω * represents the angular velocity in the open-loop given coordinate system, t represents the time, and △ω represents the angular acceleration in the open-loop given coordinate system.

[0049] The electrical angle provided by the open-loop generator, that is, the electrical angle in the open-loop given coordinate system is:

[0050] θ * = ∫ω * dt (3).

[0051] Step S120, analyzing the change state of the first electrical angle difference monitored in step S110, and adding a starting current to the motor until the motor accelerates to reach the target speed, and then switching the motor from an open-loop state to a closed-loop state.

[0052] In one embodiment, Figure 3 As shown, according to the change trend of the first electrical angle difference, a starting current is added to the motor so that the speed of the rotor (eg angular acceleration) increases from 0 to the target speed. The target speed is determined according to the difference between the electromagnetic torque of the motor and the load torque.

[0053] like Figure 3 As shown in FIG. 1 , the speed ramp corresponds to the speed ramping up from 0 to the target speed position in S120. In the open-loop given coordinate system, the starting current is added, and the speed is ramped up from 0 to the target speed.

[0054] The voltage equation of the surface-mounted permanent magnet synchronous motor in the dq coordinate system is:

[0055]

[0056] Among them, u d represents the projection of the stator voltage on the d-axis; u q represents the projection of the stator voltage on the q axis; R represents the stator resistance; i d 、i q Represent the d-axis current and q-axis current respectively; L d , L q Respectively represent the equivalent inductance of the motor on the d-axis and q-axis; ω e represents the electrical angular velocity; ψ i Represents the stator flux.

[0057] In one embodiment, the rising state of the rotor speed is determined using the following expression:

[0058]

[0059]

[0060] Among them, T e Represents electromagnetic torque, n p represents the number of pole pairs, i q represents the q-axis current in the actual coordinate system, θ represents the electrical angle of the rotor in the actual coordinate system, ω represents the angular velocity in the actual coordinate system, T L represents the load torque, and J represents the moment of inertia of the rotor.

[0061] From formula (5), we can see that when the motor load torque increases, the rotor angular acceleration will decrease. * q * The initial position of the coordinate system lags behind the initial position of the dq coordinate system, and △θ1 will also decrease accordingly, resulting in The component on the q axis increases, and the electromagnetic torque increases accordingly, resulting in an increase in the rotor angular acceleration. If the current is greater than the peak current required during the starting process, it can reach a balance again. If the motor load torque decreases, similarly, it can eventually reach a balance state.

[0062] In the step of switching the motor from an open-loop state to a closed-loop state, the step further includes: performing coordinate transformation on the electrical angle before the switching to ensure that the electrical angle of the motor remains unchanged before and after the switching. Specifically, after the motor speed is accelerated to a target speed, the motor is switched to a closed-loop state, and at the switching moment, the electrical angle before the switching is used to perform coordinate transformation to ensure that the angle remains unchanged before and after the switching.

[0063] A closed-loop given coordinate system (ie, d′q′ coordinate system) is defined, and the rotor position in the closed-loop given coordinate system is θ′.

[0064] At the moment when the open-loop operation switches to the closed-loop operation, the closed-loop given coordinate system is instantly aligned with the open-loop given coordinate system, and the rotor position in the closed-loop given coordinate system is equal to the rotor position in the open-loop given coordinate system. At the same time, the rotor position in the closed-loop given coordinate system after the assignment is Park transformed. In other words, at the moment when the open-loop operation switches to the closed-loop operation, the d′q′ coordinate system is instantly aligned with the d′q′ coordinate system. * q * coordinate system, and let θ′=θ * .

[0065] Specifically, the second angle difference Δθ2 at the switching moment is recorded.

[0066] Then, θ′ is used as the angle of voltage and current Park transformation to ensure that the electrical angle remains unchanged before and after switching, such as Figure 2 (b) shown. Among them, I s represents the stator current vector, I ds ,I qs They represent the components of the stator current on the d-axis and q-axis respectively.

[0067] The specific formula is:

[0068]

[0069] Where C represents the Park transformation matrix.

[0070] Next, in step S130, the motor current is adjusted so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero.

[0071] In step S130, when the second electrical angle difference is set to zero, the current component in the closed-loop given coordinate system is projected to the actual coordinate system to ensure that the q-axis current component value in the actual coordinate system remains unchanged during the switching process, and the integral value of the PI controller on the current loop in the closed-loop given coordinate system is projected to the actual coordinate system to ensure that the integral value of the PI controller in the actual coordinate system remains unchanged during the switching process.

[0072] The second electrical angle difference is reduced to 0, and the current is adjusted at the same time. The current target value in the given coordinate system and the integral in the current loop are projected to the actual coordinate system to ensure that the q-axis current value remains unchanged before and after the switching.

[0073] like Figure 2 As shown in (c), let the second electrical angle difference △θ = 0, and at the same time, the current component i′ on the d′q′ coordinate system d and i q ′ is projected onto the dq coordinate system to ensure that i in the dq coordinate system during the switching process q The component value remains unchanged; at the same time, the integral value of the PI controller on the d′ axis and q′ axis in the current loop is projected onto the dq coordinate system to ensure that the integral value of the PI controller in the dq coordinate system remains unchanged during the switching process.

[0074] In one embodiment, the q-axis and d-axis components are projected using the following expressions:

[0075] A=A′cos△θ2 (8)

[0076] B=B′sin△θ2 (9)

[0077] Wherein, △θ2 represents the second electrical angle difference, A represents the q-axis component of the parameter to be projected (the integral value of the current or PI controller) in the actual coordinate system, A′ represents the q′-axis component of the parameter to be projected in the closed-loop given coordinate system, B represents the d-axis component of the parameter to be projected (the integral value of the current or PI controller) in the actual coordinate system, and B′ represents the d′-axis component of the parameter to be projected in the closed-loop given coordinate system. The second electrical angle difference is obtained by calculating the difference between the electrical angle of the rotor in the actual coordinate system and the electrical angle in the closed-loop given coordinate system.

[0078] Finally, in step S140, when the d-axis current of the motor drops to 0, the startup is completed.

[0079] like Figure 2 As shown in (d), the motor current is controlled and the d-axis current is slowly reduced to 0, thereby completing the startup.

[0080] After the startup is completed (ie, step S140), at this time, the estimated rotor position (ie, electrical angle) is the same as the actual rotor position (electrical angle), so the actual rotor position can be switched to the estimated rotor position.

[0081] Based on the above motor starting control method, an embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed to run a starting control method for a permanent magnet synchronous motor. The computer program can run computer instructions, and the computer instructions include computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc.

[0082] Computer-readable storage media may include: any entity or device that can carry computer program code, recording media, USB flash drives, mobile hard disks, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0083] It should be noted that the content contained in computer-readable storage media can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, the content contained in computer-readable storage media does not include electrical carrier signals and telecommunication signals.

[0084] On the other hand, based on the above motor starting control method, an embodiment of the present invention further provides a starting control system for a permanent magnet synchronous motor. The motor starting control system is used to implement the above motor starting control method.

[0085] Figure 4 Schematic diagram of the structure of the starting control system for a permanent magnet synchronous motor according to an embodiment of the present application. Figure 4 As shown, the motor starting control system described in the embodiment of the present invention includes: an open-loop state data acquisition module 41, a state switching control module 42, a closed-loop control module 43 and a starting completion module 44.

[0086] Specifically, the open-loop state data acquisition module 41 is implemented according to the method described in the above step S110, and is configured to define the initial position in the open-loop state and position the rotor winding at the initial position, and record the first electrical angle difference between the open-loop given coordinate system and the actual coordinate system; the state switching control module 42 is implemented according to the method described in the above step S120, and is configured to analyze the changing state of the first electrical angle difference, and add a starting current to the motor until the motor accelerates to reach the target speed, and then switches the motor from the open-loop state to the closed-loop state; the closed-loop control module 43 is implemented according to the method described in the above step S130, and is configured to adjust the current of the motor so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero; the startup completion module 44 is implemented according to the method described in the above step S140, and is configured to complete the startup when the d-axis current of the motor drops to 0.

[0087] The present invention discloses a novel I / F starting method for a permanent magnet synchronous motor based on a smooth switching strategy. The present invention first switches to a closed-loop state and ensures that the angle remains unchanged before and after the switching, thereby achieving smooth switching between the open-loop state and the closed-loop state. Secondly, the current is adjusted by setting the electrical angle difference to 0 and projecting the current value of the q-axis current and the current loop integral to remain unchanged before and after the switching, thereby reducing the current and speed impact. Finally, the d-axis current value is slowly reduced to 0 to achieve i d = 0. Compared with other methods, the algorithm of the present invention is simpler, and the smooth switching from the I / F open-loop state to the closed-loop state is achieved by first switching to the closed-loop state and then adjusting the current, thereby reducing the impact of the current and the speed.

[0088] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0089] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0090] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it 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 a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0091] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0092] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0093] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A startup control method for a permanent magnet synchronous motor, characterized in that: include: Define an initial position in an open-loop state and position the rotor winding at the initial position, and record a first electrical angle difference between the open-loop given coordinate system and the actual coordinate system; Analyze the change state of the first electrical angle difference, and add a starting current to the motor until the motor accelerates to reach a target speed, and then switch the motor from an open-loop state to a closed-loop state; By regulating the current of the motor, the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero; When the d-axis current of the motor drops to 0, the startup is completed.

2. The startup control method according to claim 1, characterized in that: In the step of defining an initial position in an open-loop state and positioning the rotor winding at the initial position, and recording a first electrical angle difference between the open-loop given coordinate system and the actual coordinate system, the method comprises: In the open-loop state, the rotation direction and initial position of the rotor are controlled by controlling the magnitude and direction of the DC voltage applied to the stator winding, so that the initial position in the open-loop state lags behind the initial position of the actual coordinate system of the rotor by 90°; A first electrical angle difference representing the electrical angle deviation between the rotor position in the open-loop state and the actual rotor position is recorded.

3. The startup control method according to claim 2, characterized in that: The first electrical angle difference is calculated using the following expression: △θ1=θ-θ * oh * =∫Δωdt θ * =∫ω * dt Among them, △θ1 represents the first electrical angle difference, θ represents the electrical angle of the rotor in the actual coordinate system, and θ * Represents the electrical angle in the open-loop given coordinate system, ω * represents the angular velocity in the open-loop given coordinate system, △ω represents the angular acceleration in the open-loop given coordinate system, and t represents time.

4. The startup control method according to any one of claims 1 to 3, characterized in that: The step of analyzing the change state of the first electrical angle difference and adding a starting current to the motor includes: According to the changing trend of the first electrical angle difference, a starting current is added to the motor so that the rotor speed increases from 0 to a target speed, wherein the target speed is determined according to the difference between the electromagnetic torque of the motor and the load torque.

5. The startup control method according to claim 4, characterized in that: The following expression is used to determine the rising state of the rotor speed: Among them, T e Represents electromagnetic torque, n p represents the number of pole pairs, i q represents the q-axis current in the actual coordinate system, ψ i represents the stator flux, θ represents the electrical angle of the rotor in the actual coordinate system, ω represents the angular velocity in the actual coordinate system, T L represents the load torque, J represents the moment of inertia of the rotor, and t represents time.

6. The startup control method according to claim 4 or 5, characterized in that: The step of switching the motor from an open-loop state to a closed-loop state also includes: The electrical angle before switching is transformed to ensure that the electrical angle of the motor remains unchanged before and after switching, including: At the same time when the open-loop operation switches to the closed-loop operation, the closed-loop given coordinate system is instantly aligned with the open-loop given coordinate system, and the rotor position in the closed-loop given coordinate system is equal to the rotor position in the open-loop given coordinate system. At the same time, the rotor position in the closed-loop given coordinate system after the assignment is subjected to Park transformation.

7. The startup control method according to claim 4 or 5, characterized in that: The step of regulating the current of the motor so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero includes: When the second electrical angle difference is set to zero, the current component in the closed-loop given coordinate system is projected to the actual coordinate system to ensure that the q-axis current component value in the actual coordinate system remains unchanged during the switching process, and the integral value of the PI controller on the current loop in the closed-loop given coordinate system is projected to the actual coordinate system to ensure that the integral value of the PI controller in the actual coordinate system remains unchanged during the switching process.

8. The startup control method according to claim 7, characterized in that: The q-axis and d-axis components are projected using the following expressions: A=A′cos△θ2 B=B′sin△θ2 Among them, △θ2 represents the second electrical angle difference, A represents the q-axis component of the parameter to be projected in the actual coordinate system, A′ represents the q′-axis component of the parameter to be projected in the closed-loop given coordinate system, B represents the d-axis component of the parameter to be projected in the actual coordinate system, and B′ represents the d′-axis component of the parameter to be projected in the closed-loop given coordinate system.

9. A computer-readable storage medium, characterized in that: It contains a series of instructions for executing the method steps as claimed in any one of claims 1 to 8.

10. A starting control system for a permanent magnet synchronous motor, characterized in that: include: An open-loop state data acquisition module, configured to define an initial position in an open-loop state and position the rotor winding at the initial position, and record a first electrical angle difference between an open-loop given coordinate system and an actual coordinate system; a state switching control module, configured to analyze the change state of the first electrical angle difference, and add a starting current to the motor until the motor accelerates to reach a target speed, and then switch the motor from an open-loop state to a closed-loop state; A closed-loop control module is configured to adjust the current of the motor so that the q-axis current of the motor remains unchanged when the second electrical angle difference between the closed-loop given coordinate system and the actual coordinate system is reduced to zero; The startup completion module is configured to complete the startup when the d-axis current of the motor drops to 0.

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