阅读说明：本技术 一种内置式永磁同步电机最大转矩电流比控制方法 (Method for controlling maximum torque current ratio of built-in permanent magnet synchronous motor ) 是由 史婷娜 陈志伟 阎彦 王志强 谷鑫 于 2020-03-23 设计创作，主要内容包括：本发明公开一种内置式永磁同步电机最大转矩电流比控制方法,包括以下步骤：1)通过采样得到电机的三相定子电流i<Sub>a</Sub>、i<Sub>b</Sub>、i<Sub>c</Sub>,然后通过坐标变换得到d、q坐标系下的电流i<Sub>dr</Sub>、i<Sub>qr</Sub>；通过旋转变压器获取电机的转子位置角θ和机械转速ω<Sub>r</Sub>；2)提取转矩对电流角的导数信息dT<Sub>e</Sub>/dβ,并将导数信息dT<Sub>e</Sub>/dβ作为积分器的输入,产生d轴电流的给定值i<Sub>dref</Sub>,在给定转矩T<Sub>eref</Sub>下,得到q轴电流的给定值i<Sub>qref</Sub>；将PI控制器的输出加上前馈解耦项,得到d轴定子电压参考值v<Sub>dref</Sub>和q轴定子电压参考值v<Sub>qref</Sub>；3)采用电压空间矢量脉宽调制方法得到6路PWM脉冲触发信号,控制两电平电压源型逆变器工作,从而驱动电机旋转。(The invention discloses a method for controlling the maximum torque current ratio of a built-in permanent magnet synchronous motor, which comprises the following steps: 1) obtaining three-phase stator current i of motor by sampling a 、i b 、i c Then obtaining the current i under d and q coordinate systems through coordinate transformation dr 、i qr (ii) a Obtaining rotor position angle theta and mechanical rotation speed omega of motor through rotary transformer r (ii) a 2) Extracting derivative information dT of torque to current angle e D β, and the derivative information dT e The/d β is used as the input of the integrator to generate the given value i of the d-axis current dref At a given torque T eref Then, a given value i of the q-axis current is obtained qref (ii) a Adding a feedforward decoupling term to the output of the PI controller to obtain a d-axis stator voltage reference value v dref And q-axis statorPressure reference value v qref (ii) a 3) And 6 paths of PWM pulse trigger signals are obtained by adopting a voltage space vector pulse width modulation method, and the two-level voltage source type inverter is controlled to work, so that the motor is driven to rotate.)

1. A control method for the maximum torque current ratio of a built-in permanent magnet synchronous motor is characterized by comprising the following steps:

1) obtaining three-phase stator current i of motor by sampling_a、i_b、i_cThen obtaining the current i under d and q coordinate systems through coordinate transformation_dr、i_qr(ii) a Obtaining a rotor position angle theta and a mechanical rotation speed omega of a motor through a rotary transformer installed on the motor_r；

2) Defining the given torque value of the motor as T_erefActual torque of the motor is T_e(ii) a Extracting derivative information dT of torque to current angle_eD β, and the derivative information dT_eThe/d β is used as the input of the integrator to generate the given value i of the d-axis current_drefAt a given torque T_erefThen, a given value i of the q-axis current is obtained_qref(ii) a D-axis current is set to a given value i_drefMinus d-axis current i_drObtaining d-axis current error value, and setting q-axis current to a given value i_qrefMinus the q-axis current i_qrObtaining a q-axis current error value, respectively taking the d-axis current error value and the q-axis current error value as the input of a PI (proportional integral) controller, and adding a feedforward decoupling term to the output of the PI controller to obtain a d-axis stator voltage reference value v_drefAnd q-axis stator voltage referenceValue v_qref；

3) Combining the rotor position angle theta obtained in the step 1) and the d-axis stator voltage reference value v obtained in the step 2)_drefAnd q-axis stator voltage reference v_qrefAs the input of the voltage space vector pulse width modulation method, 6 paths of PWM pulse trigger signals are obtained by adopting the voltage space vector pulse width modulation method, and the two-level voltage source type inverter is controlled to work, so that the motor is driven to rotate.

2. The maximum torque current ratio control method of the interior permanent magnet synchronous motor according to claim 1, characterized in that in step 2), a given value i of q-axis current_qrefIs generated by the following formula:

in the formula, L_d、L_qIs the motor inductance value under the d-q coordinate system; lambda [ alpha ]_fIs a permanent magnet flux linkage; n is_pThe number of pole pairs of the motor is shown.

3. The maximum torque to current ratio control method of interior permanent magnet synchronous motor according to claim 1, characterized in that the derivative information dT of torque to current angle in step 2)_eThe extraction of/d β is as follows:

d, q axis current i of motor_d、i_qThe following relationship exists with respect to the current angle β

In the formula I_sIs the stator current amplitude, i_d、i_qActual d and q axis currents i of the motor respectively_drAnd i_qrThe current value after being filtered by a low-pass filter;

and is also provided with

Can be obtained by the two formulas

Accurate derivative information of the torque to the current angle can be obtained through the method.

4. The method for controlling the maximum torque current ratio of the interior permanent magnet synchronous motor according to claim 3, wherein the partial derivative information of the torque to the d-axis current and the q-axis current is extracted as follows:

(401) reference value v of d-axis stator voltage_drefAnd q-axis stator voltage reference v_qrefAdding upper dead zone compensation to obtain v_{d_com}And v_{q_com}V is to be_{d_com}、v_{q_com}And d-axis current i_drAnd q-axis current i_qrAs the input quantity of the low-pass filter, and then obtaining the output quantity v of the low-pass filter_d、v_q、i_dAnd i_q(ii) a The output quantity of the filter is utilized to obtain the actual torque value T of the motor through the following formula_e：

Wherein R is the motor stator resistance value omega_eThe electrical angular velocity of the motor;

(402) complementary square-wave signals Δ i of defined appropriate amplitude and frequency₁(t) and Δ i₂(t) are each independently

Wherein A is a value of suitable magnitude, T is time, N is any positive real number, T_sIs the control period of the system;

superimposing the square wave signal of the above form on i obtained by step (401)_q、i_dThen, get i_qAnd i_dTorque equation after injection of Square wave signals, as shown below

In the formula, T_e ^h(i_d,i_q+Δi₁(t))、T_e ^h(i_d,i_q+Δi₂(t))、T_e ^h(i_d+Δi₁(t),i_q) And T_e ^h(i_d+Δi₂(t),i_q) Respectively superposing square wave signals to obtain actual torque signals of the motor;

by T_e ^h(i_d,i_q+Δi₁(t)) is an example, at point (i)_d、i_q) The vicinity is periodically changed to point (i)_d、i_q) Performing binary Taylor series expansion

Known from mathematical formula

The above formula does not contain i_qTerms, and therefore their second and higher partial derivatives are all 0, the developed binary Taylor series expression can be expressed as

By the same token, i can be obtained_qInjection of Δ i₂Torque expression of (t)

Adding the two formulas and subtracting the actual torque value T of the motor_eTo obtain

In the same manner, obtain

5. The maximum torque current ratio control method of the interior permanent magnet synchronous motor according to claim 4, wherein the torque T is_eThe expressions and the torque expressions injected with square wave signals should avoid the influence of motor parameters, and the specific expression is as follows:

(501) when the motor parameters are known, the torque T is adjusted_eSubstituting the expression and the torque expression of the injected square wave signal into the formula obtained in claim 4:

the required torque T can be obtained_eTo i_dAnd i_qThe offset information of the magnetic resonance imaging system is obtained by the need of the AC and DC axis inductor L in the offset calculation process_d、L_qPermanent magnet flux linkage lambda_fInformation, torque T, to avoid the effect of parameter changes on the derivation information_eThe expression and the torque expression of the injected square wave signal are transformed as follows

(502) Substituting the equation involved in step (501) into the torque T_eThe expression and the torque expression of the injected square wave signal can be obtained

Because the d-axis inductance L is compared with the q-axis inductance change in the MTPA phase_dSmall change, small Δ i₁(t) and Δ i₂And (t) the influence of d-axis inductance change on the acquisition of the offset information can be weakened.

Technical Field

The invention relates to the field of motor control, in particular to a built-in permanent magnet synchronous motor maximum torque current ratio control method based on virtual complementary square wave signal injection.

Background

The built-in Permanent Magnet Synchronous Motor (PMSM) has the characteristics of compact structure and high power density, and is widely applied to an electric vehicle driving system. For an interior permanent magnet synchronous motor, in order to fully utilize reluctance Torque, a Maximum Torque current ratio (MTPA) control method is often adopted. The determination of the maximum torque to current ratio operating point depends on the motor parameters. However, the parameters of the interior permanent magnet synchronous motor are influenced by environment, flux linkage saturation and cross coupling, and the interior permanent magnet synchronous motor presents a high nonlinear characteristic. How to weaken the influence of the motor parameters on the determination of the MTPA point becomes the key of the research content. At a constant current vector magnitude, there is an optimum current angle to maximize the motor output torque, which is called the MTPA angle, and the mathematical relationship shows that the derivative of torque to current angle is zero. Therefore, a derivative of torque with respect to current angle of zero is a characteristic of the electric machine operating in a maximum torque to current ratio regime. How to extract the derivative information of the torque to the current angle becomes the key for realizing the maximum torque current ratio of the motor. The MTPA control method based on virtual signal injection is a widely applied maximum torque-current ratio control method, and the currently used control methods of the virtual signal injection method mainly include two methods: 1) MTPA control method based on virtual sine wave signal injection, 2) MTPA control method based on virtual single square wave signal injection. The MTPA control method based on virtual sinusoidal signal injection is characterized in that a sinusoidal signal is superposed on a detected current angle, then derivative information of torque to the current angle is obtained through a low-pass filter and a band-pass filter, the difference between the derivative information and a given value is zero, then a PI controller is used for adjusting a d-axis current given value, and finally the derivative of the torque to the current angle is zero, namely the motor realizes the maximum torque-current ratio control. However, the dynamic performance of the control system is affected by the use of more filters. The MTPA control method based on virtual single square wave signal injection is characterized in that a square wave signal is superposed on a detected current angle, and the rest part of the superposed signal minus a torque value is regarded as derivative information of torque to the current angle. The control method reduces the use of filters and improves the rapidity of a control system. However, since the torque is a trigonometric function with respect to the current angle, the remaining part is considered that the derivative information of the torque with respect to the current angle is inaccurate, and thus it is difficult to obtain an accurate maximum torque to current ratio operating point.

Therefore, how to accurately acquire the derivative information of the torque to the current angle becomes the key for realizing the maximum torque-current ratio control of the interior permanent magnet synchronous motor based on the virtual signal injection method.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a maximum torque-current ratio control method of a built-in permanent magnet synchronous motor, which can accurately extract the derivative information of torque to current angle.

The purpose of the invention is realized by the following technical scheme:

a maximum torque current ratio control method for a built-in permanent magnet synchronous motor comprises the following steps:

1) obtaining three-phase stator current i of motor by sampling_a、i_b、i_cThen obtaining the current i under d and q coordinate systems through coordinate transformation_dr、i_qr(ii) a Obtaining a rotor position angle theta and a mechanical rotation speed omega of a motor through a rotary transformer installed on the motor_r；

2) Defining the given torque value of the motor as T_erefActual torque of the motor is T_e(ii) a Extracting derivative information dT of torque to current angle_eD β, and the derivative information dT_eThe/d β is used as the input of the integrator to generate the given value i of the d-axis current_drefAt a given torque T_erefThen, a given value i of the q-axis current is obtained_qref(ii) a D-axis current is set to a given value i_drefMinus d-axis current i_drObtaining d-axis current error value, and setting q-axis current to a given value i_qrefMinusq-axis current i_qrObtaining a q-axis current error value, respectively taking the d-axis current error value and the q-axis current error value as the input of a PI (proportional integral) controller, and adding a feedforward decoupling term to the output of the PI controller to obtain a d-axis stator voltage reference value v_drefAnd q-axis stator voltage reference v_qref；

3) Combining the rotor position angle theta obtained in the step 1) and the d-axis stator voltage reference value v obtained in the step 2)_drefAnd q-axis stator voltage reference v_qrefAs the input of the voltage space vector pulse width modulation method, 6 paths of PWM pulse trigger signals are obtained by adopting the voltage space vector pulse width modulation method, and the two-level voltage source type inverter is controlled to work, so that the motor is driven to rotate.

Further, the given value i of the q-axis current in the step 2)_qrefIs generated by the following formula:

in the formula, L_d、L_qIs the motor inductance value under the d-q coordinate system; lambda [ alpha ]_fIs a permanent magnet flux linkage; n is_pThe number of pole pairs of the motor is shown.

Further, the derivative information dT of the torque to the current angle in step 2)_eThe extraction of/d β is as follows:

d, q axis current i of motor_d、i_qThe following relationship exists with respect to the current angle β

In the formula I_sIs the stator current amplitude, i_d、i_qActual d and q axis currents i of the motor respectively_drAnd i_qrThe current value after being filtered by a low-pass filter;

and is also provided with

Can be obtained by the two formulas

Accurate derivative information of the torque to the current angle can be obtained through the method.

Further, the partial derivative information of the torque to the d-axis current and the q-axis current is extracted as follows:

(401) reference value v of d-axis stator voltage_drefAnd q-axis stator voltage reference v_qrefAdding upper dead zone compensation to obtain v_{d_com}And v_{q_com}V is to be_{d_com}、v_{q_com}And d-axis current i_drAnd q-axis current i_qrAs the input quantity of the low-pass filter, and then obtaining the output quantity v of the low-pass filter_d、v_q、i_dAnd i_q(ii) a The output quantity of the filter is utilized to obtain the actual torque value T of the motor through the following formula_e：

Wherein R is the motor stator resistance value omega_eThe electrical angular velocity of the motor;

(402) complementary square-wave signals Δ i of defined appropriate amplitude and frequency₁(t) and Δ i₂(t) are each independently

Wherein A is a value of suitable magnitude, T is time, N is any positive real number, T_sIs the control period of the system;

superimposing the square wave signal of the above form on i obtained by step (401)_q、i_dThen, get i_qAnd i_dTorque equation after injection of Square wave signals, as shown below

In the formula, T_e ^h(i_d,i_q+Δi₁(t))、T_e ^h(i_d,i_q+Δi₂(t))、T_e ^h(i_d+Δi₁(t),i_q) And T_e ^h(i_d+Δi₂(t),i_q) Respectively superposing square wave signals to obtain actual torque signals of the motor;

by T_e ^h(i_d,i_q+Δi₁(t)) is an example, at point (i)_d、i_q) The vicinity is periodically changed to point (i)_d、i_q) Performing binary Taylor series expansion

Known from mathematical formula

The above formula does not contain i_qTerms, and therefore their second and higher partial derivatives are all 0, the developed binary Taylor series expression can be expressed as

By the same token, i can be obtained_qInjection of Δ i₂Torque expression of (t)

The two formulas are combinedAdding and subtracting the actual torque value T of the motor_eTo obtain

In the same manner, obtain

Further, torque T_eThe expressions and the torque expressions injected with square wave signals should avoid the influence of motor parameters, and the specific expression is as follows:

(501) when the motor parameters are known, the torque T is adjusted_eSubstituting the expression and the torque expression of the injected square wave signal into the formula obtained in claim 4:

the required torque T can be obtained_eTo i_dAnd i_qThe offset information of the magnetic resonance imaging system is obtained by the need of the AC and DC axis inductor L in the offset calculation process_d、L_qPermanent magnet flux linkage lambda_fInformation, torque T, to avoid the effect of parameter changes on the derivation information_eThe expression and the torque expression of the injected square wave signal are transformed as follows

(502) Substituting the equation involved in step (501) into the torque T_eThe expression and the torque expression of the injected square wave signal can be obtained

Because the d-axis inductance L is compared with the q-axis inductance change in the MTPA phase_dSmall change, small Δ i₁(t) and Δ i₂And (t) the influence of d-axis inductance change on the acquisition of the offset information can be weakened.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. different from the existing method of directly injecting a square wave signal along the current angle, the method extracts the partial derivative information of the torque to the d-axis current and the q-axis current by respectively injecting a pair of complementary square wave signals to the d-axis current and the q-axis current of the motor, and then indirectly obtains the derivative information of the torque to the current angle by using a full differential equation.

2. According to the invention, the offset derivative information of the torque to the d axis and the q axis is extracted by respectively injecting a pair of complementary square wave signals into the d axis current and the q axis current of the motor, and then the derivative information of the torque to the current angle is obtained by utilizing a full differential equation, so that the use of more filters in the existing injection based on sine signals is avoided, and the rapidity of the whole control system is improved.

3. The method for controlling the maximum torque current ratio of the built-in permanent magnet synchronous motor based on the virtual complementary square wave signal injection is simple to realize, can accurately extract derivative information of torque to a current angle, can accurately realize the maximum torque current ratio control of the built-in permanent magnet synchronous motor, and improves the rapidity of a control system.

Drawings

FIG. 1 is a system block diagram of a maximum torque-to-current ratio control method of an interior permanent magnet synchronous motor based on virtual complementary square wave signal injection.

Fig. 2 is a block diagram of the derivative information extraction of the torque versus current angle of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

As shown in fig. 1, the method for controlling the maximum torque-current ratio of the interior permanent magnet synchronous motor based on the injection of the virtual complementary square wave signal of the invention comprises the following steps:

1) firstly, three-phase stator current i of the motor is obtained through sampling_a、i_b、i_cThen obtaining the current i under d and q coordinate systems through coordinate transformation_dr、i_qr(ii) a Obtaining a rotor position angle theta and a mechanical rotation speed omega of an electric machine through a rotary transformer mounted on the electric machine_r。

2) Extracting dT_eThe/d β information is used as the input of the integrator to generate the given value i of the d-axis current_drefAt a given torque T_erefGiven value of q-axis current i_qrefIs generated by the following formula:

in the formula, L_d、L_qIs the motor inductance value under the d-q coordinate system; lambda [ alpha ]_fIs a permanent magnet flux linkage; n is_pThe number of pole pairs of the motor is shown.

D-axis current is set to a given value i_drefMinus d-axis current i_drObtaining d-axis current error value, and setting q-axis current to a given value i_qrefMinus the q-axis current i_qrObtaining q-axis current error value, and respectively making d-axis current error value and q-axis current error valueFor the input of the PI controller, a feedforward decoupling term is obtained by the following formula:

v_dff＝-ω_eL_qi_q

v_qff＝ω_e(L_di_d+λ_f)

in the formula, v_dffFeedforward decoupling term, v, being the d-axis component_qffA feed forward decoupling term that is the q-axis component.

Adding the feedforward decoupling term and the output term of the PI controller to obtain a d-axis stator voltage reference value v_drefAnd q-axis stator voltage reference v_qref。

3) Combining the rotor position angle theta obtained in the step 1) and the d-axis stator voltage reference value v obtained in the step 2)_drefAnd q-axis stator voltage reference v_qrefAs the input of the voltage space vector pulse width modulation method, 6 paths of PWM pulse trigger signals are obtained by adopting the voltage space vector pulse width modulation method, and the two-level voltage source type inverter is controlled to work, so that the motor is driven to rotate.

As shown in FIG. 2, the derivative information dT of the torque versus current angle of the present invention_eThe extraction method of/d β comprises the following steps:

(1) obtaining the obtained d-axis stator voltage reference value v_drefAnd q-axis stator voltage reference v_qrefAdding upper dead zone compensation to obtain v_{d_com}And v_{q_com}V is to be_{d_com}、v_{q_com}And obtaining d-axis current i in step 1_drAnd q-axis current i_qrAs the input quantity of the low-pass filter, the output quantity v of the low-pass filter is obtained after filtering_d、v_q、i_dAnd i_q. The torque value T can be obtained by the following formula by using the output quantity of the filter_e：

Wherein R is the motor stator resistance value omega_eIs the electrical angular velocity of the motor.

(2) Defining appropriate amplitude and frequencyComplementary square wave signal Δ i₁(t) and Δ i₂(t) are each independently

Wherein A is a value of suitable magnitude, T is time, N is any positive real number, T_sIs the control period of the system.

Superimposing a square wave signal of the form described above on i obtained by (1)_q、i_dThen, get i_qAnd i_dTorque equation after injection of Square wave signals, as shown below

In the formula, T_e ^h(i_d,i_q+Δi₁(t))、T_e ^h(i_d,i_q+Δi₂(t))、T_e ^h(i_d+Δi₁(t),i_q) And T_e ^h(i_d+Δi₂(t),i_q) Respectively are motor actual torque signals after the square wave signals are superposed.

By T_e ^h(i_d,i_q+Δi₁(t)) is an example, at point (i)_d、i_q) The vicinity is periodically changed so that the point (i) is reached_d、i_q) Performing binary Taylor series expansion

Known from mathematical formula

The above formula does not contain i_qTerms, and therefore their second and above partial derivatives are all 0, the developed binary Taylor series expression can be expressed as

By the same token, i can be obtained_qInjection of Δ i₂Torque expression of (t)

Adding the two formulas and subtracting T_eCan obtain the product

In the same manner, can obtain

When the motor parameters are known, the torque T is adjusted_eThe expression and the torque expression of the injected square wave signal are substituted into the two formulas to obtain the required partial derivative information. However, since the ac and dc axis inductance and the permanent magnet flux linkage information are required in the partial derivative calculation process, the torque T is required to avoid the influence of the parameter change on the partial derivative calculation_eThe expression and the torque expression of the injected square wave signal are transformed as follows

Above formula brings in torque T_eThe expression and the torque expression of the injected square wave signal can be obtained

Although still containing the d-axis inductance term, the d-axis inductance changes less and by a small Δ i than the q-axis inductance change during the MTPA phase₁(t) and Δ i₂And (t) the influence of d-axis inductance change on the acquisition of the offset information can be weakened.

(3) The d and q axis currents have the following relationship with the current angle β

In the formula I_sIs the stator current magnitude.

And is also provided with

Can be obtained by the two formulas

Accurate derivative information of the torque to the current angle can be obtained through the method.

In summary, the method extracts the partial derivative information of the torque to the d axis and the q axis by injecting a pair of complementary square wave signals into the d axis current and the q axis current of the motor respectively, and then obtains the derivative information of the torque to the current angle by using a full differential equation, thereby realizing the maximum torque-current ratio control method of the built-in permanent magnet synchronous motor. The control method does not need excessive filters, so that the control system has better dynamic performance. Meanwhile, the extraction of the derivative information is more accurate.

The present invention is not limited to the above-described embodiments. The foregoing description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many changes and modifications to the invention without departing from the spirit and scope of the invention as defined in the appended claims.