Motor control method and system

Abstract

The application provides a motor control method and system, comprising: injecting a high-frequency alternating voltage signal on a d-axis voltage, estimating an initial value of a rotor angle of a motor; applying a positive direct current component on a q-axis voltage, continuously estimating the rotor angle of the motor, and obtaining a rotor angle trend of the motor; and judging a magnetic pole direction according to the rotor angle trend and a current rotating speed of the motor, so as to obtain a rotor magnetic pole polarity.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology, and in particular to a motor control method and system. Background Technology

[0002] In the field of motors, brushless DC motors (BLDC) and permanent magnet synchronous motors are widely used, gradually replacing DC motors and other motors due to their high power density, small size, and high efficiency. Meanwhile, sensorless starting control (FOC) is becoming increasingly prevalent. Sensorless control eliminates the need for position sensors, reducing costs. However, improving motor starting performance in sensorless control has become a key concern in the industry.

[0003] When the motor operates at zero and low speeds, the back electromotive force (EMF) is small, making it impossible to accurately calculate the motor's angle and speed. The pulsed high-frequency injection method, however, can effectively track the rotor's position. This method is highly adaptable to motor parameters and robust. However, in position estimation, it is necessary to determine the rotor's magnetic pole position, making the accuracy of this determination crucial. Traditional magnetic pole determination methods typically rely on the motor's saturated salient pole effect. By injecting positive and negative pulses of equal amplitude, the slope or magnitude of the d-axis current is judged to determine the magnetic pole direction. This method requires a high degree of salient pole effect from the motor. In BLDC and permanent magnet synchronous motors, the salient pole effect is often not significant, leading to problems with the accuracy of the determined magnetic pole position. Summary of the Invention

[0004] The purpose of this invention is to provide a motor control method and system to solve the problem that it is difficult to determine the rotor magnetic pole polarity using the pulse high-frequency injection method in existing brushless DC motors and permanent magnet synchronous motors.

[0005] To solve the above-mentioned technical problems, the present invention provides a motor control method, comprising:

[0006] A high-frequency AC voltage signal is injected into the d-axis voltage to estimate the initial value of the motor's rotor angle;

[0007] A positive DC component is applied to the q-axis voltage, and the rotor angle of the motor is continuously estimated to obtain the rotor angle trend of the motor.

[0008] The direction of the magnetic poles is determined based on the rotor angle trend and the current speed of the motor to obtain the rotor magnetic pole polarity.

[0009] Optionally, in the motor control method described above,

[0010] The step of applying a positive DC component to the q-axis voltage and continuously estimating the rotor angle of the motor to obtain the rotor angle trend of the motor includes:

[0011] By applying a positive DC component to the q-axis voltage, a set of rotor angles θ1, θ2...θx of the motor are estimated successively.

[0012] Calculate a set of angle differences between two adjacent estimated times: Δθ1 = θ1 - θcalc, Δθ2 = θ2 - θ1, ..., Δθx = θx - θx-1; where θcalc is the initial value of the rotor angle.

[0013] Whenever one of the angle differences is greater than zero, the positive count is incremented;

[0014] Whenever one of the angle differences is less than zero, the reverse count is incremented;

[0015] When the forward count or reverse count is greater than N, the forward count or reverse count greater than N represents the rotor angle trend of the motor.

[0016] Optionally, in the motor control method described above,

[0017] The current speed of the motor is the speed corresponding to the rotor angle that serves as the minuend in the angle difference corresponding to the forward or reverse counting when it increases to greater than N.

[0018] Optionally, in the motor control method, determining the magnetic pole direction based on the rotor angle trend and the current motor speed to obtain the rotor magnetic pole polarity includes:

[0019] When the rotor angle trend is a positive count greater than N, and the current speed is greater than the first threshold, the rotor magnetic pole polarity of the motor is N pole;

[0020] When the rotor angle trend is a negative count greater than N, and the current speed is less than the second threshold, the rotor magnetic pole polarity of the motor is S pole;

[0021] Wherein, the first threshold is greater than 0, the second threshold is less than 0, and N is a positive integer.

[0022] Optionally, the motor control method further includes:

[0023] The current rotor angle of the motor is calculated based on the rotor magnetic pole polarity and the initial value of the rotor angle.

[0024] Optionally, in the motor control method, calculating the current rotor angle of the motor based on the rotor magnetic pole polarity and the initial rotor angle value includes:

[0025] When the rotor magnetic pole polarity is N, the current rotor angle of the motor is: θ = θcalc;

[0026] When the rotor magnetic pole polarity is S pole, the current rotor angle of the motor is: θ=θcalc+π;

[0027] Where θ is the current rotor angle of the motor, and θcalc is the initial value of the rotor angle.

[0028] Optionally, the motor control method further includes:

[0029] When the rotor magnetic pole polarity is N, the current rotor angle of the motor is: θ = θcur;

[0030] When the rotor magnetic pole polarity is S pole, the current rotor angle of the motor is: θ=θcur+π;

[0031] Wherein, θ is the current rotor angle of the motor, and θcur is the rotor angle corresponding to the current rotational speed.

[0032] Optionally, in the motor control method described above,

[0033] The amplitude of the positive DC component is between 0.5% and 2% of the bus voltage.

[0034] Optionally, in the motor control method described above,

[0035] The frequency range of the high-frequency AC voltage signal is between 500Hz and 2KHz, and the amplitude is between 1% and 20% of the input bus voltage.

[0036] The present invention also provides a motor control system implementing the motor control method described above, comprising:

[0037] Inverter circuit;

[0038] The SVPWM module is configured to control the inverter circuit;

[0039] The coordinate transformation module is configured to work in conjunction with the current loop and the speed loop to process the sampled current in the inverter circuit and then control the SVPWM module.

[0040] The position detection error information extraction module is configured to detect the current signal iq on the q-axis through a bandpass filter and a lowpass filter and then provide it to the phase-locked loop.

[0041] A phase-locked loop (PLL) is configured to obtain angular velocity information ωc based on the current signal iq on the q-axis, and then obtain rotor angle information through an integration stage, providing this information to the speed loop and magnetic pole determination module; and

[0042] The magnetic pole determination module is configured to determine the magnetic pole polarity based on the estimated rotor angle information θ and angular velocity information ωc (current rotational speed) and provide it to the coordinate transformation module.

[0043] In the motor control method and system provided by this invention, a high-frequency injection starting method for determining rotor position based on speed and angle trend is provided. By applying a positive DC component to the q-axis voltage of the (sensorless FOC motor), the rotor angle of the motor is calculated, and the rotor angle trend of the motor is obtained. The magnetic pole direction is determined based on the rotor angle trend and the current speed of the motor. By applying a positive DC component to the q-axis voltage, the magnetic pole direction is determined based on the calculated current speed and rotor angle trend, which greatly improves the accuracy of magnetic pole determination and does not rely on the salient pole effect of the motor, thus having a wide range of applications.

[0044] Compared with the prior art, the present invention has the following substantial features and significant advantages: The rotor magnetic pole determination method of the present invention can accurately determine both brushless DC motors and permanent magnet synchronous motors. The determination method is simple, highly reliable, and does not rely on the salient pole effect of the motor. Other determination methods cannot accurately determine the magnetic pole polarity when the salient pole effect of the motor is not obvious, while the method of the present invention can accurately determine the magnetic pole polarity in this case, with higher reliability and determination accuracy, greatly improving the adaptability of the motor. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of a motor control method according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram illustrating the principle of a motor control method according to an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the structure of a motor control system according to an embodiment of the present invention. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0049] It should be noted that the components in the various figures may be shown exaggeratedly for illustrative purposes and are not necessarily to scale. In each figure, the same reference numerals are used for components that are identical or have the same function.

[0050] In this invention, unless otherwise specified, "arranged on," "arranged above," and "arranged on" do not exclude the possibility of an intermediate element between them. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain cases, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0051] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0052] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0053] It should also be noted that, in the embodiments of the present invention, only a portion of the components or parts may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, necessary components or parts can be added as needed for specific scenarios. Furthermore, unless otherwise stated, features in different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0054] It should also be noted that, within the scope of this invention, the terms "same," "equal," and "equal to" do not imply that the two values ​​are absolutely equal, but rather allow for a certain reasonable margin of error. In other words, the terms also encompass "substantially the same," "substantially equal," and "substantially equal to." Similarly, in this invention, the directional terms "perpendicular to," "parallel to," etc., also encompass the meanings of "substantially perpendicular to" and "substantially parallel to."

[0055] Furthermore, the numbering of the steps in the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps may be executed in different orders.

[0056] The motor control method and system proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0057] The purpose of this invention is to provide a motor control method and system to solve the problem that it is difficult to determine the rotor magnetic pole polarity using the pulse high-frequency injection method in existing brushless DC motors and permanent magnet synchronous motors.

[0058] To achieve the above objectives, the present invention provides a motor control method and system, comprising: injecting a high-frequency AC voltage signal onto the d-axis voltage to estimate the initial value of the motor rotor angle; applying a positive DC component onto the q-axis voltage to continuously estimate the rotor angle of the motor and obtain the rotor angle trend of the motor; and determining the magnetic pole direction based on the rotor angle trend and the current speed of the motor to obtain the rotor magnetic pole polarity.

[0059] Figures 1-3 Embodiments of the present invention are provided, and the specific implementation steps are as follows: Figure 1As shown, this embodiment provides a motor control method, mainly applied to sensorless FOC motors operating at low speeds, including: injecting a high-frequency AC voltage signal onto the d-axis voltage to estimate the initial value of the motor's rotor angle; applying a positive DC component onto the q-axis voltage to continuously estimate the motor's rotor angle and obtain the rotor angle trend; and determining the magnetic pole direction based on the rotor angle trend and the motor's current speed to obtain the rotor magnetic pole polarity.

[0060] Specifically, in the motor control method, applying a positive DC component to the q-axis voltage and continuously estimating the rotor angle of the motor to obtain the rotor angle trend includes: applying a positive DC component to the q-axis voltage and successively estimating a set of rotor angles θ1, θ2...θx; calculating a set of angle differences between two adjacent estimation times Δθ1 = θ1 - θcalc, Δθ2 = θ2 - θ1...Δθx = θx - θx-1; where θcalc is the initial value of the rotor angle; whenever an angle difference is greater than zero, the forward count increases; whenever an angle difference is less than zero, the reverse count increases; when the forward count or reverse count is greater than N, the forward count or reverse count greater than N represents the rotor angle trend of the motor. The current speed of the motor is the speed corresponding to the rotor angle that is the minuend in the angle difference corresponding to when the forward count or reverse count increases to greater than N.

[0061] Furthermore, in the motor control method, determining the magnetic pole direction based on the rotor angle trend and the current speed of the motor to obtain the rotor magnetic pole polarity includes: when the rotor angle trend is a positive count greater than N, and the current speed is greater than a first threshold, the rotor magnetic pole polarity of the motor is N pole; when the rotor angle trend is a negative count greater than N, and the current speed is less than a second threshold, the rotor magnetic pole polarity of the motor is S pole; wherein, the first threshold is greater than 0, the second threshold is less than 0, and N is a positive integer. It also includes: calculating the current rotor angle of the motor based on the rotor magnetic pole polarity and the initial value of the rotor angle.

[0062] Specifically, in the motor control method, calculating the current rotor angle of the motor based on the rotor magnetic pole polarity and the initial rotor angle value includes: when the rotor magnetic pole polarity is N, the current rotor angle of the motor is: θ = θcalc; when the rotor magnetic pole polarity is S, the current rotor angle of the motor is: θ = θcalc + π; where θ is the current rotor angle of the motor and θcalc is the initial rotor angle value.

[0063] Furthermore, the motor control method further includes: when the rotor magnetic pole polarity is N, the current rotor angle of the motor is: θ = θcur; when the rotor magnetic pole polarity is S, the current rotor angle of the motor is: θ = θcur + π; where θ is the current rotor angle of the motor, and θcur is the rotor angle corresponding to the current rotational speed.

[0064] Specifically, in the motor control method described above, the amplitude of the positive DC component is between 0.5% and 2% of the bus voltage. The frequency range of the high-frequency AC voltage signal is between 500Hz and 2kHz, and the amplitude is between 1% and 20% of the input bus voltage.

[0065] The present invention also provides a motor control system implementing the motor control method described above, comprising: an inverter circuit; an SVPWM module configured to control the inverter circuit; a coordinate transformation module configured to be combined with a current loop and a speed loop to process the sampled current in the inverter circuit and then control the SVPWM module; a position detection error information extraction module configured to detect the current signal iq on the q-axis through a bandpass filter and a lowpass filter and then provide it to a phase-locked loop; a phase-locked loop configured to obtain angular velocity information ωc based on the current signal iq on the q-axis, and then obtain rotor angle information through an integration element, and provide it to a speed loop and a magnetic pole determination module; and a magnetic pole determination module configured to determine the magnetic pole polarity based on the estimated rotor angle information θ and the angular velocity information ωc (current rotational speed), and provide it to the coordinate transformation module.

[0066] In the motor control method and system provided by this invention, a high-frequency injection starting method for determining rotor position based on speed and angle trend is provided. By applying a positive DC component to the q-axis voltage of the (sensorless FOC motor), the rotor angle of the motor is calculated, and the rotor angle trend of the motor is obtained. The magnetic pole direction is determined based on the rotor angle trend and the current speed of the motor. By applying a positive DC component to the q-axis voltage, the magnetic pole direction is determined based on the calculated current speed and rotor angle trend, which greatly improves the accuracy of magnetic pole determination and does not rely on the salient pole effect of the motor, thus having a wide range of applications.

[0067] Compared with the prior art, the present invention has the following substantial features and significant advantages: The rotor magnetic pole determination method of the present invention can accurately determine both brushless DC motors and permanent magnet synchronous motors. The determination method is simple, highly reliable, and does not rely on the salient pole effect of the motor. Other determination methods cannot accurately determine the magnetic pole polarity when the salient pole effect of the motor is not obvious, while the method of the present invention can accurately determine the magnetic pole polarity in this case, with higher reliability and determination accuracy, greatly improving the adaptability of the motor.

[0068] Specifically, in the motor control method described above, the sensorless FOC motor is a permanent magnet synchronous motor; this embodiment provides a method for determining the rotor magnetic pole polarity of a permanent magnet synchronous motor, which specifically includes the following steps:

[0069] Step one: In the motor control method described above, the rotor position is tracked using a pulsed high-frequency injection method to obtain the initial value of the estimated rotor angle. Tracking the rotor position using the pulsed high-frequency injection method includes: injecting a high-frequency AC voltage signal Ud onto the d-axis of the estimated synchronous rotating coordinate system; detecting the current signal iq on the q-axis; and obtaining the initial value of the estimated rotor angle through signal extraction and processing, a PI controller, and an integration stage. Specifically, injecting a high-frequency AC voltage signal Ud onto the d-axis of the estimated synchronous rotating coordinate system... dinj High-frequency AC voltage signal U dinj The frequency range is between 500Hz and 2KHz, and the amplitude is between 1% and 20% of the input bus voltage.

[0070] Step two: After obtaining the initial value of the estimated rotor angle, determine the rotor magnetic pole polarity to ascertain whether the current initial value of the estimated rotor angle needs calibration compensation based on the rotor magnetic pole polarity. In the motor control method described above, determining the rotor magnetic pole polarity includes: applying a positive DC voltage component Uq to the estimated synchronous rotating coordinate system q-axis. The amplitude of this DC component must be small enough to prevent significant motor rotation (some processes even require no motor rotation at all). In this embodiment, the DC voltage component is between 0.5% and 2% of the bus voltage; obtaining the estimated rotor angle and / or rotor speed after applying the DC voltage component using a high-frequency injected angle estimator; and recording the rotor angle change trend and / or rotor speed change trend within the response time Δt.

[0071] Furthermore, the motor control method further includes: providing the rotor speed to a low-pass filter to obtain the difference Δθ between two adjacent estimated rotor angles and the rotor speed n; determining whether the number of times the rotor angle increases within the response time is greater than N based on the difference in rotor angles; determining whether the number of times the rotor angle decreases within the response time is greater than N based on the difference in rotor angles; determining whether the rotor speed within the response time is greater than a first threshold based on the rotor speed n; and / or determining whether the rotor speed within the response time is less than a second threshold based on the rotor speed n; wherein the first threshold is greater than 0 and the second threshold is less than 0.

[0072] Optionally, the motor control method further includes: if the number of times the rotor angle increases is greater than N and / or the rotor speed is greater than a first threshold, then the rotor magnetic pole polarity is determined to be N; if the number of times the rotor angle decreases is greater than N and / or the rotor speed is less than a second threshold, then the rotor magnetic pole polarity is determined to be S. The calculation method for the difference Δθ between two adjacent estimated rotor angles includes: when a DC voltage component is applied to the q-axis, the initial rotor angle is θcalc. After the q-axis DC voltage component is applied, the current angle calculated by the phase-locked loop is θ1, then Δθ1 = θ1 - θcalc; the angle calculated by the phase-locked loop next time is θ2, then Δθ2 = θ2 - θ1; ​​and so on, to obtain a series of rotor angle differences Δθ1, Δθ2, ... Δθx.

[0073] Step three, in the motor control method described above, also includes: if Δθ1 is greater than 0, the number of times the rotor angle increases is incremented by 1; if Δθ1 is less than 0, the number of times the rotor angle decreases is incremented by 1, and so on for Δθ1, Δθ2, ..., Δθx; when the number of times the rotor angle increases is greater than the count value N and the current speed is greater than a certain positive value ωpos, it is determined that the rotor magnetic pole polarity is N at this time, and the final angle is equal to the currently calculated angle, i.e., θ = θcalc;

[0074] Step 4: When the number of times the rotor angle decreases is greater than the count value N and the current speed is less than a certain negative value ωneg, it is determined that the rotor magnetic pole polarity is S pole at this time. The final angle at this time is the angle compensation of the current calculated angle by 180°, that is, θ=θcalc+π.

[0075] like Figure 2 As shown, the motor control method further includes: α-β as a two-phase stationary coordinate system, and dq as the actual rotating coordinate system. The estimated rotating coordinate system is given by θ, where the actual rotor position is θ and the estimated rotor position is θ. The estimation error is then... The form of pulsed high-frequency voltage injection is as follows:

[0076]

[0077] In the formula, u inj For the total injected voltage vector, u dinj For the injected d-axis voltage component, u qinj The injected q-axis voltage component; the injected high-frequency voltage signal is a high-frequency cosine signal U. dinj =U inj *cosω h t; where U inj Let cosω be the magnitude of the injected d-axis voltage. h t represents the injected d-axis AC voltage component, ω h The angular frequency of the AC voltage; from Figure 2 The relationship between the estimated coordinates and the actual coordinate system can be derived:

[0078]

[0079]

[0080] In the above formula, For the estimated dq-axis voltage, u d ,u q This represents the actual dq-axis voltage. For the estimated dq-axis current, i d i q Given the actual dq-axis current; the relationship between iq and θerr is derived:

[0081]

[0082] Where Icp is the positive-sequence component of the high-frequency current, and Icn is the negative-sequence component of the high-frequency current; it can be seen from the formula that when θ err When it approaches 0, The rotor position is obtained by using the convergence of the q-axis current to 0.

[0083] like Figure 3 As shown, this embodiment also provides a motor control system implementing the motor control method described above, including: an inverter circuit; an SVPWM module configured to control the inverter circuit; a coordinate transformation module configured to be combined with a current loop and a speed loop to process the sampled current in the inverter circuit and then control the SVPWM module; a position detection error information extraction module configured to detect the current signal iq on the q-axis through a bandpass filter and a lowpass filter and then provide it to the phase-locked loop; a phase-locked loop configured to obtain angular velocity information ωc based on the current signal iq on the q-axis, and then obtain rotor angle information through an integration element, and provide it to the speed loop and the magnetic pole determination module; and a magnetic pole determination module configured to determine the magnetic pole polarity based on the estimated angle information θ and the angular velocity information ωc, and provide it to the coordinate transformation module.

[0084] When implemented in FOC, the specific implementation is as follows: Figure 3As shown. ia,ib,ic are the detected three-phase currents, iα,iβ are the currents in the stationary coordinate system, ω*c is the given speed, ωc is the estimated speed, i*d is the given d-axis current, and id is the feedback d-axis current. i*q is the given q-axis current, and iq is the feedback q-axis current. ud is the d-axis voltage output by the control loop, and uq is the q-axis voltage output by the control loop. Uinjcosωht is the injected d-axis AC voltage, and uqinj is the DC component applied to the q-axis. uα,uβ are the output voltages in the stationary coordinate system. sinωht is the function for extracting current information, and iqh is the q-axis current signal output after passing through a bandpass filter. f(Δθerr) is the extracted angle error signal. BPF is the bandpass filter, LPF is the low-pass filter, PI is the proportional-integral controller, the speed loop is the loop controller for controlling the speed, the current loop is the controller for controlling the output current, and SVPWM is the space vector modulation section.

[0085] A high-frequency AC voltage signal Uinjcosωht is injected onto the d-axis of the estimated synchronous rotating coordinate system. Then, the current signal iq on the q-axis is detected. The current containing rotor position information is obtained by extracting the position error signal. This current is then controlled by a phase-locked loop (PLL) PI controller to obtain the angular velocity information ωc. Finally, the rotor angle information is obtained through integration. After a delay t1, the PLL has fully converged. A small positive DC voltage component Uq is then applied to the q-axis. After a response time t2, based on the trends in angle and speed changes, the difference Δθ between two adjacent estimated angles and the speed n are obtained. The speed needs to pass through a low-pass filter to reduce interference. It is determined whether the number of increases or decreases in angle changes during this period exceeds a certain count value N. Simultaneously, it is determined whether the current speed is greater than a certain positive value or less than a certain negative value. Combining these two conditions, the polarity of the current rotor magnetic poles is determined to be either N or S.

[0086] Specifically, in the motor control system, the coordinate transformation module converts the detected three-phase currents ia, ib, ic into currents iα, iβ in the stationary coordinate system, and converts the currents iα, iβ in the stationary coordinate system into the feedback d-axis current id and the feedback q-axis current iq.

[0087] The position detection error information extraction module is configured to detect the current signal iq on the q-axis through a bandpass filter and a lowpass filter, and then provide it to the PI controller of the phase-locked loop to obtain the angular velocity information ωc. The rotor angle information is then obtained through an integration stage.

[0088] The angular velocity information ωc is used as the estimated rotational speed. The difference between the given rotational speed ω*c and the estimated rotational speed ωc is provided to the velocity loop to obtain the given q-axis current i*q.

[0089] The difference between the given d-axis current i*d and the feedback d-axis current id, and the difference between the given q-axis current i*q and the feedback q-axis current iq are provided to the current loop to obtain the d-axis voltage ud and the q-axis voltage uq output by the current loop.

[0090] The difference between the d-axis voltage ud output by the current loop and the injected d-axis AC voltage Uinjcosωht, and the difference between the q-axis voltage uq output by the current loop and the DC component uqinj applied on the q-axis are provided to the coordinate transformation module to obtain the output voltage uα,uβ in the stationary coordinate system.

[0091] After a delay of t1, the phase-locked loop converges and a positive DC voltage component Uq is applied to the q-axis. After a response time of t2, based on the rotor angle change trend and speed change trend at this time, the difference Δθ between the two adjacent estimated angles and the speed n are obtained, thereby determining the current rotor magnetic pole polarity.

[0092] This invention belongs to the field of motor control, and specifically relates to a high-frequency injection starting method for determining rotor position based on speed and angle trends. By applying a positive DC voltage to the q-axis, the rotor's changing trend, after calculation by a phase-locked loop, is reflected in the calculated speed and angle information. Determining the current magnetic pole polarity based on these trends provides a more reliable assessment. Furthermore, this method does not rely on the salient pole effect of the motor and is fully applicable to both brushless DC motors and permanent magnet synchronous motors.

[0093] In summary, the above embodiments have provided detailed descriptions of different configurations of the motor control method and system. Of course, this invention includes, but is not limited to, the configurations listed in the above embodiments. Any modifications made based on the configurations provided in the above embodiments are within the scope of protection of this invention. Those skilled in the art can apply the knowledge gained from the above embodiments to other situations.

[0094] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0095] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method of controlling an electric machine, characterized by, include: A high-frequency AC voltage signal is injected into the d-axis voltage to estimate the initial value of the motor's rotor angle; A positive DC component is applied to the q-axis voltage, and the rotor angle of the motor is continuously estimated to obtain the rotor angle trend of the motor. as well as The direction of the magnetic poles is determined based on the rotor angle trend and the current speed of the motor to obtain the rotor magnetic pole polarity. The step of applying a positive DC component to the q-axis voltage and continuously estimating the rotor angle of the motor to obtain the rotor angle trend of the motor includes: A positive direct current component is applied on the q-axis voltage, and a group of rotor angles θ1, θ2, … θn of the motor are estimated in sequence x ; A set of angle differences Δθ1=θ1-θcalc, Δθ2=θ2-θ1... Δθx=θx-θx-1 is calculated for two adjacent estimated times; wherein θcalc is the initial value of the rotor angle. x -θ x-1 ; wherein θcalc is the initial value of the rotor angle. Whenever one of the angle differences is greater than zero, the positive count is incremented; Whenever one of the angle differences is less than zero, the reverse count is incremented; When the forward count or reverse count is greater than N, the forward count or reverse count greater than N represents the rotor angle trend of the motor.

2. The motor control method of claim 1, wherein, The current speed of the motor is the speed corresponding to the rotor angle that serves as the minuend in the angle difference corresponding to the forward or reverse counting when it increases to greater than N.

3. The motor control method as described in any one of claims 1-2, characterized in that, The step of determining the magnetic pole direction based on the rotor angle trend and the current speed of the motor to obtain the rotor magnetic pole polarity includes: When the rotor angle trend is a positive count greater than N, and the current speed is greater than the first threshold, the rotor magnetic pole polarity of the motor is N pole; When the rotor angle trend is a negative count greater than N, and the current speed is less than the second threshold, the rotor magnetic pole polarity of the motor is S pole; Wherein, the first threshold is greater than 0, the second threshold is less than 0, and N is a positive integer.

4. The motor control method as described in claim 1, characterized in that, Also includes: The current rotor angle of the motor is calculated based on the rotor magnetic pole polarity and the initial rotor angle value.

5. The motor control method as described in claim 4, characterized in that, The step of calculating the current rotor angle of the motor based on the initial value, according to the rotor magnetic pole polarity and the initial value of the rotor angle, includes: When the rotor magnetic pole polarity is N, the current rotor angle of the motor is: α = θcalc; When the rotor magnetic pole polarity is S pole, the current rotor angle of the motor is: α = θcalc + π; Where α is the current rotor angle of the motor based on the initial value, and θcalc is the initial value of the rotor angle.

6. The motor control method as described in claim 1, characterized in that, Also includes: When the rotor magnetic pole polarity is N, the current rotor angle of the motor based on the current speed is: β=θcur; When the rotor magnetic pole polarity is S pole, the current rotor angle of the motor based on the current speed is: β=θcur +π; Wherein, β is the current rotor angle of the motor based on the current speed, and θcur is the rotor angle corresponding to the current speed.

7. The motor control method as described in claim 1, characterized in that: The amplitude of the positive DC component is between 0.5% and 2% of the bus voltage.

8. The motor control method as described in claim 1, characterized in that: The frequency range of the high-frequency AC voltage signal is between 500Hz and 2KHz, and the amplitude is between 1% and 20% of the input bus voltage.

9. A motor control system implementing the motor control method as described in claim 1, characterized in that, include: Inverter circuit; The SVPWM module is configured to control the inverter circuit; The coordinate transformation module is configured to work in conjunction with the current loop and the speed loop to process the sampled current in the inverter circuit and then control the SVPWM module. The position detection error information extraction module is configured to detect the current signal iq on the q-axis through a bandpass filter and a lowpass filter and then provide it to the phase-locked loop. The phase-locked loop is configured to obtain angular velocity information ωc based on the current signal iq on the q-axis, and then obtain rotor angle information through an integration element, which is then provided to the speed loop and magnetic pole determination module. as well as The magnetic pole determination module is configured to determine the magnetic pole polarity based on the estimated rotor angle information θ and angular velocity information ωc, and provide this information to the coordinate transformation module.

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