阅读说明：本技术 低噪声低频脉振信号注入永磁电机转子位置的检测方法 (Method for detecting position of low-noise low-frequency pulse vibration signal injected into permanent magnet motor rotor ) 是由 周洪雷 董震 董清华 王品贺 郭晓宇 于 2021-09-06 设计创作，主要内容包括：本发明涉及一种低噪声低频脉振信号注入永磁电机转子位置的检测方法,在旋转坐标系内注入低频的电压信号,根据响应电流幅值,以自适应学习方式注入电压幅值,记录最后一拍注入电压幅值为V-(inj),在观测的旋转坐标系中,对坐标系的轴注入低频脉振电压,对输出电流进行采样,提取响应电流幅值,通过观测器获取低频响应电流中包含的转子角度信息,得到转子速度,经过算法提取得到转子位置信息,实现闭环控制,得到转子位置信息。本发明能够保证系统环路控制连续性、稳定性的前提下,提取永磁电机转子位置信息,且消除了由于传统高频信号注入引起的噪声,实现了低噪声的永磁电机信号注入无位置传感器控制。(The invention relates to a method for detecting the position of a rotor of a low-noise low-frequency pulse vibration signal injected into a permanent magnet motor inj In the observed rotational coordinate system In the coordinate system And injecting low-frequency pulse vibration voltage into the shaft, sampling the output current, extracting the amplitude of the response current, acquiring rotor angle information contained in the low-frequency response current through an observer to obtain the speed of the rotor, extracting rotor position information through an algorithm to realize closed-loop control, and acquiring the position information of the rotor. The invention can extract the position information of the permanent magnet motor rotor on the premise of ensuring the continuity and stability of the system loop control, eliminates the noise caused by the traditional high-frequency signal injection and realizes the low-noise permanent magnet motor signal injection position-free sensor control.)

1. The detection method for injecting the low-noise low-frequency pulse vibration signal into the position of the permanent magnet motor rotor is characterized by comprising the following steps of:

injecting low-frequency voltage signals into a rotating coordinate system, injecting voltage amplitudes in a self-adaptive learning mode according to response current amplitudes, and recording the amplitude of the last-beat injection voltage as V_inj；

Step two, in the observed rotating coordinate systemIn the coordinate systemInjecting low-frequency pulse vibration voltage into the shaft, sampling output current, and extracting the amplitude of response current;

and step three, obtaining rotor angle information contained in the low-frequency response current through an observer to obtain the rotor speed, and obtaining rotor position information through algorithm extraction to realize closed-loop control.

2. The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor according to claim 1, wherein the method comprises the following steps: in the first step, the process of injecting the voltage amplitude in a self-adaptive learning mode comprises the steps of increasing the injection voltage amplitude by a preset step parameter in a shutdown state, monitoring the output line current,

if the response current amplitude is smaller than the preset value of the target current, keeping the preset step length parameter and continuing to increase the injection voltage;

if the response current amplitude is larger than the preset value of the target current but not more than the target current, continuing to increase the voltage amplitude by using the adjustment step size parameter until the response current exceeds the target line current;

if the response current amplitude is larger than the target current, reducing the voltage amplitude by a preset step parameter until the response current is smaller than the target line current;

finally, the voltage amplitude of the last beat of injection is recorded as V_injThe adaptive injection voltage learning ends.

3. The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor according to claim 2, wherein the method comprises the following steps: the preset step length parameter, the adjustment step length parameter and the preset value of the target current are adjusted within the range of 1-100%.

4. The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor according to claim 1, wherein the method comprises the following steps: step two, in the observed rotating coordinate systemIs/are as followsThe shaft is injected with low-frequency pulsating voltage, and the amplitude is V obtained by learning in the step one_injIn a static two-phase coordinate system, extracting a response current amplitude I with the same frequency as the injected low-frequency voltage through Fourier transform_αh,βh；

Sampling the output current, and performing Clark conversion on the output current to obtain the output current in a two-phase static coordinate system, wherein the Clark conversion formula is as follows:

wherein i_α,βRepresenting the current in a two-phase stationary frame, i_U,V,WOutputting current for three phases;

and in the two-phase static coordinate system, extracting the response current amplitude with the same frequency as the injection voltage through Fourier transform.

5. The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor according to claim 1, wherein the method comprises the following steps: in the third step, the rotor angle information contained in the low-frequency response current is solved through an angle observer, and is differentiated to obtain the rotor speed, and the rotor speed is fed back to realize closed-loop control;

the voltage equation of the motor is set as,

equation (2) is a standard RL Circuit model, where u_d,qIs d, q-axis voltage, i_d,qIs d, q-axis current, L_d,qIs d, q-axis inductance, R_sAs the resistance of the stator,

keeping the learning result of the voltage amplitude in the step one, injecting a sine wave signal on a d axis in a rotating coordinate system, and obtaining the rotating coordinate systemThe injection voltage of (1).

6. The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor according to claim 5, wherein the method comprises the following steps: in the third step, the injection voltage expression is adopted as,

wherein ω is_hIs the injection signal frequency;

by combining the formula (2) and the formula (3), the observation rotating coordinate system is obtainedThe response current in (1) is:

wherein Z is_d,q＝R_s+jω_hL_d,q，θ_eIs the actual electrical angle of the rotor, Δ θ_eIn order to observe the angular deviation, it is,

by passingThe coordinate transformation of the Park is represented,

the subscript 'h' denotes the component corresponding to the injection frequency,

from the equation (4), the rotation coordinate system of observationIn the coordinate system of (a) and (b),the shaft current includes rotor position deviation information Δ θ_eIt is converted as follows:

wherein the content of the first and second substances,

as can be seen from the equation (5), the rotation coordinate system is observedIn (1),the shaft current amplitude expresses rotor position information and can be based onThe rotor position is obtained by convergence of the shaft current amplitude.

Technical Field

The invention relates to a method for detecting the position of a permanent magnet motor rotor, in particular to a method for detecting the position of a permanent magnet motor rotor injected with a low-noise low-frequency pulse vibration signal.

Background

At present, the effective scheme of the conventional adopted permanent magnet synchronous motor low-speed sensorless control is a high-frequency injection scheme, and the conventional method adopts three schemes: 1. a high frequency rotational injection scheme; 2. a high frequency pulsating injection regime; 3. a high frequency square wave injection scheme.

Specifically, in the case of a permanent magnet motor operating at a low speed or at a zero speed, the prior art realizes the extraction of the rotor position by injecting a high-frequency voltage signal into the motor. The main difference with the solution of the invention is that the injected signal is characterized differently. The high-frequency rotation injection scheme is to inject a rotating voltage vector into a three-phase stator coordinate system to obtain rotor angle information. The high-frequency pulse oscillation injection scheme is to extract the rotor angle by injecting a high-frequency sine wave into a rotating coordinate system. The high-frequency square wave injection scheme is developed based on a high-frequency pulse oscillation injection scheme, and a high-frequency voltage square wave signal is injected into a rotating coordinate system to obtain a rotor angle. During implementation, after a high-frequency voltage signal is injected, a high-frequency response current is obtained through a signal extraction technology, and then rotor position information is obtained through algorithm extraction, so that the low-speed position-sensor-free closed-loop control of the permanent magnet motor is realized.

In view of practical implementation, the current conventional sensor-less control method for the permanent magnet motor based on signal injection needs to inject a high-frequency voltage signal into the motor. This necessarily causes harsh noise, limiting the use of this technology in noise-sensitive applications, at least not in certain household electrical appliance applications.

Meanwhile, lowering the frequency of the injection voltage is an effective means of reducing noise due to high-frequency voltage signal injection. However, such a processing method has a problem that signal extraction is difficult. In addition, some schemes realize the extraction of low-frequency signals by injecting discrete pulse signals. However, such discrete pulse signal injection may cause a torque shock. In addition, in order to extract the pulse signal, the loop control of the system is interrupted, the continuity of closed-loop regulation of the system is damaged, and the dynamic response capability of the system is reduced.

In view of the above-mentioned drawbacks, the present designer actively makes research and innovation to create a method for detecting the position of the rotor of the permanent magnet motor by injecting a low-noise low-frequency pulsating signal, so that the method has industrial value.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a method for detecting a position of a rotor of a permanent magnet motor injected with a low-noise low-frequency pulse vibration signal.

The invention discloses a method for detecting the position of a rotor of a low-noise low-frequency pulse vibration signal injected into a permanent magnet motor, which comprises the following steps of:

injecting low-frequency voltage signals into a rotating coordinate system, injecting voltage amplitudes in a self-adaptive learning mode according to response current amplitudes, and recording the amplitude of the last-beat injection voltage as V_inj；

Step two, in the observed rotating coordinate systemIn the coordinate systemInjecting low-frequency pulse vibration voltage into the shaft, sampling output current, and extracting the amplitude of response current;

and step three, obtaining rotor angle information contained in the low-frequency response current through an observer to obtain the rotor speed, and obtaining rotor position information through algorithm extraction to realize closed-loop control.

Further, the method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor is characterized in that in a self-adaptive learning mode, the voltage amplitude is injected in a process of increasing the voltage amplitude by a preset step length parameter in a shutdown state, and the output line current is monitored;

if the response current amplitude is smaller than the preset value of the target current, keeping the preset step length parameter and continuing to increase the injection voltage;

if the response current amplitude is larger than the preset value of the target current but not more than the target current, continuing to increase the voltage amplitude by using the adjustment step size parameter until the response current exceeds the target line current;

if the response current amplitude is larger than the target current, reducing the voltage amplitude by a preset step parameter until the response current is smaller than the target line current;

finally, the voltage amplitude of the last beat of injection is recorded as V_injThe adaptive injection voltage learning ends.

Furthermore, in the detection method for injecting the low-noise low-frequency pulse vibration signal into the position of the rotor of the permanent magnet motor, the preset step size parameter, the adjustment step size parameter and the preset value of the target current are adjusted within a range of 1% to 100%. And the related switching threshold values can be adjusted according to the actual processing condition, so that the requirement of final amplitude self-adaption is met.

Furthermore, the method for detecting the position of the rotor of the permanent magnet motor injected with the low-noise low-frequency pulse vibration signal includes the second step of observing the rotating coordinate systemOf a coordinate systemInjecting low-frequency pulsating voltage into the shaft, setting the frequency to be 20Hz and the amplitude to be V obtained by learning in the step one_injIn a static two-phase coordinate system, extracting a response current amplitude I with the same frequency as the injected low-frequency voltage through Fourier transform_αh,βh；

Sampling the output current, and performing Clark conversion on the output current to obtain the output current in a two-phase static coordinate system, wherein the Clark conversion formula is as follows:

wherein i_α,βRepresenting the current in a two-phase stationary frame, i_U,V,WOutputting current for three phases;

and in the two-phase static coordinate system, extracting the response current amplitude with the same frequency as the injection voltage through Fourier transform.

Furthermore, in the third step, the rotor angle information included in the low-frequency response current is solved through an angle observer, and is differentiated to obtain the rotor speed, and the rotor speed is fed back to realize closed-loop control, and during the implementation, a phase-locked loop may be used to form the angle observer. Of course, other approximate angle observers can be adopted, and data can be intuitively acquired as the preferred reference;

the voltage equation of the motor is set as,

equation (2) is a standard RL Circuit model, where u_d,qIs d, q-axis voltage, i_d,qIs d, q-axis current, L_d,qIs d, q-axis inductance, R_sAs the resistance of the stator,

keeping the learning result of the voltage amplitude in the step one, injecting a sine wave signal on a d axis in a rotating coordinate system, and obtaining the rotating coordinate systemThe injection voltage of (1).

Furthermore, in the above method for detecting the position of the rotor of the low-noise low-frequency pulsating signal injected into the permanent magnet motor, in the third step, an injection voltage expression is adopted,

wherein ω is_hIs the injection signal frequency;

by combining the formula (2) and the formula (3), the observation rotating coordinate system is obtainedThe response current in (1) is:

wherein Z is_d,q＝R_s+jω_hL_d,q，θ_eIs the actual electrical angle of the rotor, Δ θ_eIn order to observe the angular deviation, it is,

by passingRepresenting the Park coordinate transformation, the subscript 'h' represents the component corresponding to the injection frequency,

from the equation (4), the rotation coordinate system of observationIn the coordinate system of (a) and (b),the shaft current includes rotor position deviation information Δ θ_eIt is converted as follows:

wherein the content of the first and second substances,

as can be seen from the equation (5), the rotation coordinate system is observedIn (1),the shaft current amplitude expresses rotor position information and can be based onThe rotor position is obtained by convergence of the shaft current amplitude.

Furthermore, in the above method for detecting the position of the rotor of the permanent magnet motor by injecting the low-noise low-frequency pulsating signal, in the third step, the response current in the two-phase stationary coordinate system is expressed as,

furthermore, the method for detecting the position of the rotor of the permanent magnet motor by injecting the low-noise low-frequency pulse vibration signal comprises the step of detecting the position deviation delta theta in a response current expression in a two-phase static coordinate system_eWhen the ratio is smaller, the formula (6) is simplified into,

as shown in (7), the amplitude I of the signal response current can be injected into the two-phase stationary coordinate system under the condition of small position deviation_αh,βhDirectly obtain the inverse tangent operation to obtain the position information of the rotor,

the solving formula is that,

by the scheme, the invention at least has the following advantages:

1. the invention can extract the position information of the permanent magnet motor rotor on the premise of ensuring the continuity and stability of the loop control of the system.

2. The invention eliminates the noise caused by signal injection and realizes the low-noise permanent magnet motor signal injection position-free sensor control.

3. The invention can realize the position sensorless control of the permanent magnet motor in a low-speed operation range (below 2 Hz).

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of the detection implementation of the present invention.

Fig. 2 is a flow chart of the adaptive learning injection voltage.

Fig. 3 is a schematic diagram of an adaptive learning injection voltage waveform.

Fig. 4 is a schematic flow diagram responsive to current draw.

Fig. 5 is a schematic diagram of the spatial distribution of the coordinate system.

Fig. 6 is a schematic diagram of the implementation principle of the angle observer.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The method for detecting the position of the rotor of the low-noise low-frequency pulse vibration signal injected into the permanent magnet motor shown in fig. 1 to 6 is distinctive in that the method comprises the following steps:

step 1: and injecting a low-frequency voltage signal into the rotating coordinate system, and adaptively learning the amplitude of the injected voltage according to the amplitude of the response current. During implementation, it is recommended to limit the signal frequency to within 50Hz in order to reduce noise. Specifically, low-frequency voltage signals are injected into a rotating synchronous coordinate system, the amplitude of the injected voltage signals needs to be adaptive, and the amplitude of response current is guaranteed to reach about 50% of rated current of the motor. Meanwhile, in order to achieve low noise or even no noise, it is recommended to limit the injection voltage frequency within 50Hz, and this embodiment takes 20Hz as an example for the solution description. Meanwhile, the flow chart of the adaptive learning injection voltage amplitude is shown in fig. 2, and the corresponding response current waveform is shown in fig. 3.

Referring to fig. 1, on the basis of a standard permanent magnet motor control block diagram, the scheme adds a voltage injection part V_injAn injection current amplitude extraction FFT module and a phase-locked loop PLL module. It should be noted that the phase-locked loop PLL module used in the present invention is only one way of observing the rotor position. The above-described phase-locked loop may also be replaced with a module in which an arctangent operation is used as angle information acquisition. Fig. 2 includes the adaptation of injection voltage compensation, and the learning of the final injection voltage. The variation of the response current amplitude as the injection voltage increases and the final stage injection voltage amplitude adaptive adjustment process are given in fig. 3 by taking the phase line current as an illustration. When the target current exceeds the preset range, the injection voltage can be automatically reduced, so that the response current falls within the preset range, and the self-adaptive learning process of the injection voltage is realized.

The detection method for the rotor position has almost the same detection steps, and the first two steps are the same, but in the third step, the method obtains the angle after acquiring the angular speed information, and the arc tangent operation obtains the angular speed through the acquisition of the angular speed information, so that the detection of the rotor position is realized.

In the above test, the formulas of the calculations are the same, except that the known variables in the formulas change, but the final calculation yields consistent results.

When viewed in conjunction with the process of adaptively learning the injection voltage, it may comprise the steps of:

1) and under the shutdown condition, increasing the injection voltage amplitude by taking a step length of 2% as a preset step length parameter. During this period, the output line current is monitored, and if the amplitude is smaller than the preset value of 90% of the target current, the injection voltage is continuously increased with the step size of 2%.

2) If the response current amplitude is larger than the preset value of the target current by 90% but not more than the target current, the voltage amplitude is continuously increased by the step size of 1% of the adjustment step size parameter until the response current exceeds the target line current.

3) If the response current amplitude is larger than the target current, the voltage amplitude is reduced by the step size of 1% of the adjustment step size parameter until the response current is smaller than the target line current.

4) Recording the last beat injection voltage amplitude V_injThe adaptive injection voltage learning ends.

In practical implementation, the adjustment ranges of the preset step size parameter, the adjustment step size parameter, and the preset value of the target current may be set to 1% to 100%. Of course, the related switching threshold values can be adjusted according to the actual processing condition, and the requirement of final amplitude self-adaption is met.

It should be noted that the present invention may involve some special extreme detection during the implementation, and the adjustment ranges of the preset step size parameter, the adjustment step size parameter, and the preset value of the target current may be further extended on the basis of 1% to 100%. That is, the specific numerical values mentioned above are merely examples and do not limit the actual ranges thereof. In other words, during some special limit detections, the preset step size parameter and the adjustment step size parameter may be less than 1%, and under individual limit detections, the situation may also occur that exceeds 100%, which are special situations and are generally difficult to occur in the detection, so that details are not described herein. The present application is a test performed within the normal range.

Step 2: in the observed rotating coordinate systemIs/are as followsInjecting low-frequency pulsating voltage into the shaft, wherein the frequency is 20Hz, and the amplitude is V obtained by learning in the step 1_inj. Then, extracting a response current amplitude I with the same frequency as the injected low-frequency voltage in a static two-phase coordinate system through Fourier transform_αh,βh。

Then, the output current is sampled and subjected to Clark conversion to obtain the output current in the two-phase static coordinate system. Wherein, the Clark transformation formula adopted is as follows:

wherein i_α,βRepresenting the current in a two-phase stationary frame, i_U,V,WThree-phase output current. And in the two-phase static coordinate system, extracting the response current amplitude with the same frequency as the injection voltage through Fourier transform. A schematic diagram of the response current amplitude extraction process during actual implementation is shown in fig. 4. As can be seen from fig. 4, from top to bottom, there are the injected low-frequency sine wave voltage, the response current in the two-phase stationary coordinate system obtained by sampling, and the amplitude of the response current in the two-phase stationary coordinate system obtained after fourier extraction.

And step 3: and solving rotor angle information contained in the low-frequency response current through an observer (phase-locked loop), and differentiating the rotor angle information to obtain the rotor speed for feedback to realize closed-loop control. Since the motor operates at low speed, the effects of mutual inductance and back emf can be ignored, thus yielding the voltage equation for the motor as:

specifically, equation (2) is a standard RL Circuit model, where u_d,qIs d, q-axis voltage, i_d,qIs d, q-axis current, L_d,qIs d, q-axis inductance, R_sIs the stator resistance.

After learning the injection voltage amplitude, the result of learning in step 1 is held as the injection voltage amplitude, and a sine wave signal is injected on the d-axis in the rotating coordinate system. Since the actual position of the rotor is unknown, only the observed rotational coordinate system can be obtainedThe low frequency pulsating voltage is injected in the coordinate system, which is schematically shown in fig. 5. As can be seen from fig. 5, the coordinate system includes a two-phase stationary coordinate system, a real rotating coordinate system dq of the rotor of the motor, and an observing rotating coordinate system dq of the rotor

In view of practical implementation, the injection voltage expression adopted by the invention is as follows:

wherein, ω is_hIs the injection signal frequency.

Thus, based on the equations (2) and (3), the observation rotational coordinate system can be obtainedThe response currents in the coordinate system are as follows:

wherein, theta_eAs actual electrical angle of the rotor, Z_d,q＝R_s+jω_hL_d,q，Δθ_eTo observe the angular deviation. By usingRepresenting a Park coordinate transformation, with the subscript 'h' representing the component corresponding to the injection frequency,

meanwhile, as can be seen from the formula (4), the system is observed in a rotating coordinate systemIn the coordinate system, the coordinate system is provided with a plurality of coordinate systems,the shaft current includes rotor position deviation information Δ θ_eIt is converted as follows:

wherein the content of the first and second substances,

as can be seen from the equation (5), the rotation coordinate system is observedIn (1),the shaft current amplitude expresses rotor position information and can be based onThe rotor position is obtained by convergence of the shaft current amplitude.

In view of the angle observer shown in fig. 6, the implementation process of the present invention is as follows: it is first to outputThe current is sampled. Then, obtaining the response current amplitude I in the two-phase static coordinate system_αh,βh. Then, the coordinate system is subjected to Park transformation to obtain an observed rotating coordinate systemResponse current in coordinate systemThen, willThe shaft current is input into the PI regulator to make the shaft current converge to zero, and then the position information of the rotor can be obtainedThen for observing rotor positionDifferentiating to obtain observed angular velocityFinally, willAndused as a feedback signal to achieve closed loop control. Moreover, the angle observation scheme in fig. 6 is introduced based on the PLL scheme, and includes Park coordinate transformation, a PI observer, and a speed integration unit.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.