阅读说明：本技术 一种pmslm在低速段的无位置传感器控制方法 (Position-sensorless control method of PMSLM (permanent magnet synchronous Motor) at low-speed stage ) 是由 宋同月 颜建虎 孙芮 池松 姚超 周怡 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种PMSLM在低速段的无位置传感器控制方法,具体步骤：首先构建永磁同步直线电机的矢量控制系统,将旋转高频电压矢量信号从两相静止坐标系α轴和β轴注入,通过带通滤波器(BPF)将高频响应电流i<Sub>αout</Sub>和i<Sub>βout</Sub>滤出,再通过高频同步轴系高通滤波器(SFF),从而滤出高频负序电流i<Sub>αOUT</Sub>和i<Sub>βOUT</Sub>；其次不同工作点时,预先测量出不同两相旋转坐标系下的直轴电流i<Sub>d</Sub>、交轴电流i<Sub>q</Sub>对应的不同交直轴耦合因子γ,并通过最小二乘法拟合出γ与i<Sub>d</Sub>、i<Sub>q</Sub>的近似关系式,利用此式解出不同的γ；最后通过γ对i<Sub>αOUT</Sub>和i<Sub>βOUT</Sub>的关系式,解耦电机真实动子位置θ<Sub>r</Sub>和因交直轴耦合产生的位置偏差θ<Sub>m</Sub>,通过锁相环估计出动子位置。本发明消除了交直轴耦合效应,提高了旋转高频注入法估算精度。(The invention discloses a position-sensorless control method of a PMSLM (permanent magnet synchronous Motor) at a low-speed stage, which comprises the following specific steps: firstly, a vector control system of a permanent magnet synchronous linear motor is constructed, rotating high-frequency voltage vector signals are injected from an alpha axis and a beta axis of a two-phase static coordinate system, and a high-frequency response current i is transmitted through a band-pass filter (BPF) αout And i βout Filtering, and passing through high-frequency synchronous shafting high-pass filter (SFF), thereby filtering out high-frequency negative sequence current i αOUT And i βOUT (ii) a Secondly, when different working points are arranged, the direct-axis current i under different two-phase rotating coordinate systems is measured in advance d Quadrature axis current i q Corresponding different quadrature-direct axis coupling factors gamma, and fitting gamma and i by a least square method d 、i q The approximate relational expression of (a) is utilized to solve different gamma; finally passing through gamma pair i αOUT And i βOUT The actual rotor position theta of the decoupling motor r And the position deviation theta generated by quadrature-direct axis coupling m And estimating the position of the rotor through a phase-locked loop. The invention eliminates the quadrature-direct axis coupling effect and improves the estimation precision of the rotary high-frequency injection method.)

1. A position-sensorless control method of a PMSLM (permanent magnet synchronous Motor) at a low-speed stage is characterized by comprising the following specific steps:

step 1, constructing a vector control system of the PMSLM, injecting a rotating high-frequency voltage vector signal from an alpha axis and a beta axis of a two-phase static coordinate system, and passing a high-frequency response current i through a band-pass filter_αoutAnd i_βoutFiltering, and passing through high-frequency synchronous shafting high-pass filter to filter out high-frequency negative sequence current i_αOUTAnd i_βOUT；

Step 2, pre-measuring the direct-axis current i under different two-phase rotating coordinate systems at different working points_dQuadrature axis current i_qCorresponding different quadrature-direct axis coupling factors gamma, and fitting gamma and i by a least square method_d、i_qThe approximate relational expression of (a) is utilized to solve gamma under different conditions;

step 3, through gamma to i_αOUTAnd i_βOUTThe actual rotor position theta of the decoupling motor_rAnd the position deviation theta generated by quadrature-direct axis coupling_mAnd estimating the position of the rotor by a phase-locked loop improved by a heterodyne method.

2. The PMSLM position sensorless control method in a low speed section according to claim 1, characterized in that in step 1, the position sensorless vector control system based on the rotating high frequency voltage vector is constructed as follows:

according to i_dThe direct-axis current is given as 0 under the concept of 0-vector control, the quadrature-axis current takes the estimated speed as the speed closed-loop feedback output quantity as input, and the two-phase static voltage alpha-axis voltage u is obtained after coordinate transformation_αiBeta axis voltage u_βiThree fundamental wave voltages are output through SVPWM and a three-phase inverter and injected into a winding of the PMSLM, meanwhile, a rotating high-frequency voltage vector signal is also injected into the winding of the PMSLM, and high-frequency response current i filtered by a band-pass filter_αoutAnd i_βoutThe high-frequency synchronous shafting high-pass filter filters out high-frequency negative sequence current i under a two-phase rotating dq coordinate system, wherein the rotating angular speed of the high-frequency synchronous shafting is the same as the high-frequency rotating voltage_αOUTAnd i_βOUT。

3. The PMSLM position sensorless control method in a low speed section according to claim 1, characterized in that: high frequency negative sequence current i_αOUTAnd i_βOUTIncluding mover position information.

4. The PMSLM position sensorless control method in low speed section according to claim 1, characterized in that in step 2, the specific method is as follows:

the PMSLM can stably run at a certain working point under the traditional vector control with a position sensor, and at the moment, a direct-axis current i is correspondingly obtained_dAnd quadrature axis current i_qAt the moment, rotating high-frequency voltage vector signals are injected into the alpha axis and the beta axis of the two-phase static coordinate system, and the true rotor position theta obtained by the position sensor is obtained_mAnd a high-frequency negative-sequence current i_αOUTAnd i_βOUTSimultaneous equations to obtain corresponding different cross-direct axis coupling factors gamma, which are related to the working point, and a gamma and i are pre-fitted by least square method_d、i_qThe relational expression (c) of (c).

γ＝F(i_d,i_q)。

5. The method for controlling a position sensorless PMSLM in a low speed section according to claim 1 or 4, wherein in the step 3, the specific method is as follows:

by gamma pair of i_αOUTAnd i_βOUTThe actual rotor position theta of the decoupling motor_mAnd the position deviation theta generated by quadrature-direct axis coupling_errAnd outputting the position of the rotor to an improved phase-locked loop through a heterodyne method to estimate the position of the rotor:

in the above formula, the true mover position θ_mEstimate mover position θ_est，L_sIs a differential mode inductance, omega_hfFor injecting the rotational angular velocity of the rotating high-frequency voltage vector signal, t is the time, K is a constant related to the injection voltage and the motor parameter, i_αOUT、

the above two formulas are subtracted to obtain:

ε＝ηsin(2θ_m-2θ_est)

the mover position estimation error exists in epsilon, eta is a positive coefficient, and the mover position estimation error delta theta is made to be theta_m-θ_estWhen estimating mover position θ_estApproximation to true mover position θ_mWhen the speed is higher than the speed threshold value, the epsilon is approximately in direct proportion to delta theta, and the estimated rotor electric speed v is obtained through a proportional integral PI regulator of a phase-locked loop_estAnd obtaining the mover estimated mover position theta after the second integration_est。

Technical Field

The invention belongs to the field of motor control, and particularly relates to a position-sensorless control method of a PMSLM (permanent magnet synchronous Motor) at a low-speed stage, which is mainly applied to some special equipment doing linear motion.

Background

In traditional industrial production, linear motion usually requires a rotating motor to cooperate with complex mechanical transmission structures and conversion devices such as a coupler, a ball screw, a ball nut and the like, the efficiency is low, the robustness is poor, and the speed regulation range is greatly limited. Compared with a traditional transmission system, a Permanent Magnet Synchronous Linear Motor (PMSLM) has a higher speed regulation range; and an intermediate transmission mechanism is omitted, so that the positioning and motion control are more accurate, the robustness system is better, the system efficiency is higher, and a reliable platform is provided for linear motion under certain occasions with high speed and high efficiency. A high-precision vector control system of a permanent magnet synchronous linear motor needs to acquire the position and the speed of a motor rotor accurately in real time. The conventional vector control system utilizes mechanical sensors to acquire mover position and speed information, but the mechanical sensors not only increase the cost of the driving system, but also are easily affected by environmental factors such as temperature and humidity, and even cannot be used under certain conditions. In view of the above problems caused by position sensors, a position sensor-less control technique of PMSLM is in urgent need to be solved. The main idea of the low-speed section is to inject a rotating high-frequency voltage vector signal into a motor winding, and a response signal related to the position information of the rotor can be extracted through a detection separation technology, so that the position information and the speed of the rotor can be estimated.

The principle of the high-frequency injection method is that salient pole characteristics of the motor are utilized, and the back electromotive force fundamental wave model independent of the motor can obtain better operation performance at a low-speed section. However, when the motor load is large and the quadrature-direct axis coupling effect is strong, a large position estimation error related to the coupling effect occurs in the high-frequency signal injection method, which seriously affects the control accuracy and may cause the motor to lose step under certain conditions. The quadrature-direct axis coupling effect caused by different working points is in a nonlinear relation, so that how to find out the influence of the quadrature-direct axis coupling effect on the inductance under a certain current working point and accurately decouple the real rotor position in the rotor position estimation process is profound and far-reaching to the accuracy of PMSLM position-free control.

Disclosure of Invention

The invention aims to provide a position-sensorless control method of a PMSLM (permanent magnet synchronous motor) at a low-speed stage, aiming at the problem of the AC-DC axis coupling effect generated when a rotating high-frequency voltage vector signal is injected into a motor winding, on the basis of the traditional high-frequency signal injection method, the AC-DC axis coupling factors under different working points are measured in advance, and the AC-DC axis coupling factors are combined with a heterodyne method to improve a phase-locked loop structure so as to eliminate the coupling effect.

The technical solution for realizing the purpose of the invention is as follows: a position-sensorless control method of a PMSLM (permanent magnet synchronous Motor) at a low-speed stage comprises the following specific steps:

step 1, constructing a vector control system of the PMSLM, injecting a rotating high-frequency voltage vector signal from an alpha axis and a beta axis of a two-phase static coordinate system, and passing a high-frequency response current i through a band-pass filter_αoutAnd i_βoutFiltering, and passing through high-frequency synchronous shafting high-pass filter to filter out high-frequency negative sequence current i_αOUTAnd i_βOUT；

Step 2, pre-measuring the direct-axis current i under different two-phase rotating coordinate systems at different working points_dQuadrature axis current i_qCorresponding different quadrature-direct axis coupling factors gamma, and fitting gamma and i by a least square method_d、i_qThe approximate relational expression of (a) is utilized to solve gamma under different conditions; .

Step 3, through gamma to i_αOUTAnd i_βOUTThe actual rotor position theta of the decoupling motor_rAnd the position deviation theta generated by quadrature-direct axis coupling_mAnd estimating the position of the rotor by a phase-locked loop improved by a heterodyne method.

Compared with the prior art, the invention has the remarkable advantages that:

1) the invention considers the error of the rotary high-frequency injection method in the rotor position estimation under the condition that the permanent magnet synchronous linear motor causes different degrees of quadrature-direct axis coupling effect under different loads.

2) The invention firstly continuously changes the working point under the vector control operation of the position sensor, then injects the rotating high-frequency voltage vector signal, and processes the high-frequency negative sequence current by utilizing the real rotor position to obtain the quadrature-direct axis coupling factor.

3) Through the phase-locked loop based on the heterodyne method, the influence of quadrature-direct axis coupling on position estimation is effectively eliminated, and the position estimation precision is improved.

Drawings

FIG. 1 is a flow chart of a position sensorless control method of a PMSLM of the present invention at low speed.

FIG. 2 is a block diagram of PMSLM vector control based on a rotating high-frequency signal injection method according to the present invention.

FIG. 3 is a schematic diagram of the negative sequence high frequency current extraction of the present invention.

FIG. 4 is a schematic diagram of the measurement of the quadrature-direct axis coupling factor of the present invention.

Fig. 5 is a structural diagram of a phase-locked loop based on a heterodyne method according to the present invention.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

Compared with a traditional transmission system, a Permanent Magnet Synchronous Linear Motor (PMSLM) has a higher speed regulation range; and an intermediate transmission mechanism is omitted, so that the positioning and motion control are more accurate, the robustness system is better, the system efficiency is higher, and a reliable platform is provided for linear motion under certain occasions with high speed and high efficiency. A high-precision vector control system of a permanent magnet synchronous linear motor needs to acquire the position and the speed of a motor rotor accurately in real time. The conventional vector control system utilizes mechanical sensors (such as a grating scale, a hall sensor and the like) to acquire the position and speed information of the mover, but the mechanical sensors not only increase the cost of the driving system, but also are easily affected by environmental factors such as temperature and humidity, and even cannot be used under certain conditions. In view of the above problems caused by position sensors, a position sensor-less control technique of PMSLM is urgently needed to be solved. The main idea of the low-speed section is to inject a rotating high-frequency voltage vector signal into a motor winding, and a response signal related to the position information of the rotor can be extracted through a detection separation technology, so that the position information and the speed of the rotor can be estimated.

The principle of the high-frequency injection method is that salient pole characteristics of the motor are utilized, and the back electromotive force fundamental wave model independent of the motor can obtain better operation performance at a low-speed section. However, when the motor load is large and the quadrature-direct axis coupling effect is strong, a large position estimation error related to the coupling effect occurs in the high-frequency signal injection method, which seriously affects the control accuracy and may cause the motor to lose step under certain conditions. The quadrature-direct axis coupling effect caused by different working points is in a nonlinear relation, so the influence of the quadrature-direct axis coupling effect on the inductance is found out at a certain current working point, and the real rotor position is accurately decoupled in the rotor position estimation process.

The invention considers the influence of the quadrature-direct axis coupling effect in the high-frequency signal injection method, separates the influence generated by the coupling effect through the phase-locked loop improved by the heterodyne method, measures the quadrature-direct axis coupling factors of different working points in advance and can obtain the dynamic control performance with higher precision.

With reference to fig. 1 and fig. 2, the method for controlling a position-less sensor of a PMSLM at a low speed stage according to the present invention includes the following steps:

step 1, constructing a vector control system of a PMSLM (permanent magnet synchronous linear motor), injecting a rotating high-frequency voltage vector signal from an alpha axis and a beta axis of a two-phase static coordinate system, and passing a high-frequency response current i through a band-pass filter_αoutAnd i_βoutFiltering, and passing through high-frequency synchronous shafting high-pass filter to filter out high-frequency negative sequence current i_αOUTAnd i_βOUT：

Firstly, the current response form under the excitation of the high-frequency voltage vector signal is rotated. Assuming that three-phase windings of the permanent magnet synchronous linear motor are completely symmetrical, iron core saturation is neglected, eddy current loss and hysteresis loss are neglected, then a high-frequency voltage model of the permanent magnet synchronous linear motor in a dq coordinate system (a direct axis and a quadrature axis) of rotor magnetic field orientation can be obtained as follows:

in the formula (1), L_MIs dq-axis mutual inductance, and is an AC-DC axis coupling inductor L_c＝L_M，u_d、i_dRespectively, the direct-axis voltage and current u_q、i_qRespectively quadrature axis voltage and current, L_d、L_qRespectively a direct axis inductor and a quadrature axis inductor.

Transforming the two-phase rotating coordinate system into the two-phase static coordinate system through coordinate transformation, and injecting a rotating high-frequency voltage vector signal into an alpha beta coordinate system of the two-phase static coordinate system of the formula to obtain the following formula (2):

definition of theta_errThe position deviation caused by the quadrature-direct axis coupling is as follows:

u in formula (2)_α、i_αRespectively alpha axis voltage and current, u_β、i_βBeta axis voltage and current, theta_mFor true mover position, θ_errCommon mode inductance L for position deviation due to quadrature-direct axis coupling_a＝(L_d+L_q) /2, differential mode inductance L_s＝(L_d-L_q)/2. When a rotating high frequency voltage vector of equation (4) is injected from the α β coordinate system, a high frequency current response is produced as shown in equation (5), equation (6) being in the form of its current response vector, where u is_αhfIs an alpha-axis high-frequency voltage vector, u_βhIs a beta axis high frequency voltage vector, V_hfFor injecting a rotating high-frequency voltage vector signal amplitude, omega_hfFor injecting rotating high-frequency voltage vector signalsAngular velocity of the sign, t is time, K is a constant related to the injection voltage and motor parameters,to synthesize the current vector, j is the imaginary unit.

As can be seen from equation (6), the high-frequency current response includes a positive sequence component and a negative sequence component, but only the negative sequence component includes mover position information, and thus also includes a position shift due to quadrature-direct axis coupling. FIG. 3 is a high-frequency negative-sequence current extraction schematic diagram, in which a two-phase stationary coordinate system response current i of a motor is firstly calculated_α、i_βFiltering with band-pass filter (BPF) to obtain high-frequency response current i in formula (5)_αoutAnd i_βoutThen filtering the high-frequency current by using a high-frequency synchronous shafting high-pass filter (SFF) to obtain a high-frequency negative sequence current component i_αOUTAnd i_βOUT。

The specific process is as follows: the high-frequency current is firstly converted into high-frequency synchronous shafting, so that the original high-frequency positive sequence current can be converted into a direct-current component, and the original negative sequence current rotation angular velocity can be changed into pi x v_m/τ-2ω_hf，v_mThe rotor speed is taken as the speed, and tau is the motor polar distance. Filtering the direct current quantity by a high-pass filter, and then converting the direct current quantity back to an alpha beta shaft system to obtain alpha-axis and beta-axis high-frequency negative sequence current i shown in a formula (7)_αOUTAnd i_βOUT。

Step 2, notWhen the working point is the same, the direct-axis current i under different two-phase rotating coordinate systems is measured in advance_dQuadrature axis current i_qCorresponding different quadrature-direct axis coupling factors gamma, and fitting gamma and i by a least square method_d、i_qThe approximate relational expression of (2) is used to solve γ in different cases.

Where γ is defined as L_c/Ls, it can be seen that gamma couples the inductance L with the quadrature-direct axis_cSum-mode and difference-mode inductance L₂In this regard, when the motor is loaded differently and the control strategy is different, the motor will operate at different current operating points, which will affect L_d、L_qAnd L_cThe size of (2).

To address this problem, a simple method of pre-measuring γ is presented. Firstly, the motor is operated under the vector control of a position sensor, the load and the control strategy are changed, the motor is operated at a certain working point needing to be measured, then a rotating high-frequency voltage vector is injected into an alpha-beta shaft system, a high-frequency negative sequence current component is filtered out in the step 1, and then the real rotor position theta is utilized according to the position shown in figure 4_mProcessing the negative sequence current component:

i_αOUT·cos(2θ_m-ω_hft)+i_βOUT·sin(2θ_m-ω_hft)＝KL_c (8)

i_αOUT·sin(2θ_m-ω_hft)-i_βOUT·cos(2θ_m-ω_hft)＝KL_s (9)

the motor works at different current working points, corresponding gamma values are respectively measured, and then the gamma and i shown in the formula (11) can be fitted by using a function after coordinate transformation_d、i_qBefore step 3, the relation according to i in step 2 is completed_d、i_qObtaining the gamma value under the current working point

γ＝F(i_d,i_q) (11)

Step 3, through gamma to i_αOUTAnd i_βOUTThe actual rotor position theta of the decoupling motor_rAnd the position deviation theta generated by quadrature-direct axis coupling_mAnd estimating the position of the rotor by a phase-locked loop improved by a heterodyne method.

As can be seen from the equation (7), when the high-frequency negative-sequence current is directly treated by the heterodyne method, θ is introduced_errThe detection error of/2, therefore, it is necessary to quantitatively analyze the influence of the quadrature-direct axis coupling effect on the inductance. Handling negative sequence current components according to the improved phase locked loop structure of fig. 5

In the above formula, L_sIs a differential mode inductance, omega_hfFor injecting the rotational angular velocity of the rotating high-frequency voltage vector signal, t is the time, K is a constant related to the injection voltage and the motor parameter, i_αOUT、i_βOUTHigh-frequency negative-sequence currents of the alpha and beta axes, L, respectively_cIs an AC-DC axis coupling inductor.

By subtracting the two moieties of formula (12), one can obtain:

the mover position estimation error exists in epsilon, eta is a positive coefficient, and the mover position estimation error delta theta is made to be theta_m-θ_estWhen estimating mover position θ_estApproximation to true mover position θ_mWhen the speed is higher than the speed threshold value, epsilon is approximately proportional to delta theta, and the estimated rotor electric speed v can be obtained through a proportional integral PI regulator of a phase-locked loop_estThe mover position theta can be estimated by the mover after the second integration_estThe improved phase-locked loop structure in FIG. 5 is used to process the negative sequence current component, so as to effectively eliminate the influence of the quadrature-direct axis coupling effect.