Improved control method of built-in permanent magnet synchronous motor
阅读说明：本技术 内置式永磁同步电机的改进控制方法 (Improved control method of built-in permanent magnet synchronous motor ) 是由 杨高兴 张瑞峰 柴璐军 路瑶 贺志学 张吉斌 丁志勇 梁海刚 于 2019-10-29 设计创作，主要内容包括：本发明涉及永磁同步电机的控制方法,具体为内置式永磁同步电机的改进控制方法。解决现有使用参数在线辨识的永磁同步电机控制方法存在缺陷,使用不太理想的问题。本发明对转矩电流进行在线计算,根据电机动态参数进行实时修正,获得包含较准确的电机参数信息的电流计算模型,并利用该模型,进而计算得到转矩电流,且在低速和高速都可以对转矩电流进行实时修正,以此实现精确的转矩电流控制。该算法能够使电机运行在比较准确的工作点,具有良好的参数鲁棒性和动态响应特性。通过在前馈电压计算模块中对电机参数的变化情况进行在线估算,实现对参考电压的精确计算控制,提高电机控制精度。(The invention relates to a control method of a permanent magnet synchronous motor, in particular to an improved control method of a built-in permanent magnet synchronous motor. The method solves the problems that the existing permanent magnet synchronous motor control method using parameter online identification has defects and is not ideal in use. The invention carries out on-line calculation on the torque current, carries out real-time correction according to the dynamic parameters of the motor, obtains a current calculation model containing more accurate motor parameter information, further calculates to obtain the torque current by utilizing the model, and can carry out real-time correction on the torque current at low speed and high speed so as to realize accurate torque current control. The algorithm can enable the motor to operate at a more accurate working point, and has good parameter robustness and dynamic response characteristics. The change condition of the motor parameter is estimated on line in the feed-forward voltage calculation module, so that the accurate calculation control of the reference voltage is realized, and the control accuracy of the motor is improved.)
1. A control method for a built-in permanent magnet synchronous motor is characterized in that 4 modules are divided into a sampling calculation module (1), a motor parameter calculation module (2), a torque current calculation module (3) and a current feedforward decoupling calculation module (4);
1) sampling calculation module
Collecting DC bus voltage U of inverter dcAnd motor stator current i a、i b(ii) a For stator current i a、i bPerforming Clarke transformation and Park transformation to obtain a stator current D axis component i in a synchronous rotation coordinate system DAnd stator current Q axis component i Q；
The position sensor is used for acquiring the position angle theta of the motor rotor and calculating to obtain the electrical angular velocity omega of the motor rotor r；
2) Motor parameter calculation module
The input variables of the motor parameter calculation module are as follows:
i Qthe actual value of the Q-axis current of the motor stator is obtained;
i Q0the component of Q-axis current when the change rate of the inductance is turned;
L Q0setting values for inductance components of the Q shaft at normal temperature for measured values or motor design values at normal temperature;
L D0setting values for inductance components of the D shaft at normal temperature for measured values or motor design values at normal temperature;
ψ f0a flux linkage value at normal temperature, a measured value at normal temperature or a motor design set value;
t is the temperature of the magnetic steel;
rho is a curve coefficient and is 0.1-0.3%;
γ tthe magnetic steel temperature coefficient can be searched from a magnetic steel handbook;
the output variables are:
L Q(i Qt) is Q-axis inductance along with i QAnd the value of the change in the temperature t,
L D(t) is the value of D-axis inductance as a function of temperature t, L D(t)＝L D0γ tt；
ψ f(t) is the value of the flux linkage as a function of temperature t,. phi f(t)＝ψ f0γ tt；
ΔL err0Is a Q-axis inductor L at normal temperature Q0And D-axis inductance L D0Difference of (d), Δ L err0＝L Q0-L D0；
Δi Q0Is Q-axis actual current i QAnd i Q0Difference between, Δ i Q0＝i Q-i Q0；
3) Torque current calculation module
The torque current calculation module input variables are as follows:
T *setting torque for the motor;
ψ f0the flux linkage value of the motor is in a normal temperature state;
ΔL err0is an initial value L of the Q-axis inductance Q0And D-axis inductance initial value L D0The difference between the two;
Δi Q0is Q-axis actual current i QAnd i Q0The difference between them;
t is the temperature of the magnetic steel;
rho is a curve coefficient;
γ tmagnetic steel temperature coefficient;
U Smaxallowing a maximum phase voltage amplitude for the inverter;
the output variables are as follows:
the torque current calculation module is used for setting the torque T according to the input motor *Obtaining the D-axis current under the maximum torque current ratio calculation method through the maximum torque current ratio calculation method
Wherein the content of the first and second substances,
when the motor runs in a weak magnetic field, firstly, the amplitude U of the given reference voltage is calculated by using the D-axis and Q-axis given reference voltages fed back by the current feedforward decoupling calculation module S，U SAnd the maximum allowable phase voltage amplitude U of the inverter SmaxIs subjected to PI regulation, the regulator output is
q-axis set current
When i is Q＜i Q0When the temperature of the water is higher than the set temperature,
when i is Q≥i Q0When the temperature of the water is higher than the set temperature,
4) current feedforward decoupling calculation module
The input parameters of the current feedforward decoupling calculation module are as follows:
Δu Dgiven value for D-axis current
similarly, Δ u QGiven value for Q-axis current
given reference voltage output by current feedforward decoupling calculation module
2. The improved control method of interior permanent magnet synchronous motor according to claim 1, characterized in that, in 3) the torque current calculation module,
3. the improved control method of interior permanent magnet synchronous motor according to claim 1 or 2, characterized in that, in 3) the torque current calculation module,
Technical Field
The invention relates to a control method of a permanent magnet synchronous motor, in particular to an improved control method of a built-in permanent magnet synchronous motor.
Background
The traditional Maximum Torque current ratio (MTPA) control method of the built-in permanent magnet synchronous motor obtains D-axis current given value by carrying out derivation operation on a motor Torque model
because the current calculation formula in the maximum torque current ratio (MTPA) control method comprises parameters such as a permanent magnet flux linkage and a D-Q axis inductor, the parameters can change nonlinearly along with factors such as load disturbance, temperature change and magnetic circuit saturation in actual operation, and great fluctuation is brought to the current calculation of the maximum torque current ratio (MTPA) control method. Therefore, improving the calculation accuracy of the given current and the given voltage becomes one of the keys of the permanent magnet synchronous motor control.
In order to improve the accuracy of permanent magnet synchronous motor control, most scholars generally use a parameter online identification method; in recent years, researchers have proposed a maximum torque current ratio control method based on virtual signal injection, which includes analyzing the relationship between motor torque and power, using a detected value instead of a motor parameter, injecting a high frequency current signal into a torque formula, passing the torque signal including the high frequency signal through a band pass filter and a low pass filter according to a taylor series expansion formula to obtain a torque versus current angle change rate required for a maximum torque current ratio, and passing the torque versus current angle change rate through an integrator to be controlled to be zero, thereby realizing the maximum torque current ratio control. The calculation method for obtaining the MTPA angle by the method has the advantages of low convergence speed, long dynamic response time, complex algorithm, complex signal analysis process, poor dynamic response and poor practical application.
Disclosure of Invention
The invention solves the problems that the existing permanent magnet synchronous motor control method using parameter online identification has defects and is not ideal to use, and provides an improved control method of a built-in permanent magnet synchronous motor. The control method accurately distributes the motor current controlled by the motor by accurately determining the motor parameters in real time, so as to accurately control the motor, and the motor has good steady-state control precision and dynamic response speed; and the method is simple and has no complicated calculation process.
The invention is realized by adopting the following technical scheme: the control method of the built-in permanent magnet synchronous motor comprises the following steps of dividing the control method into 4 modules which are respectively a
1) sampling calculation module
Collecting DC bus voltage U of inverter dcAnd motor stator current i a、i b(ii) a For stator current i a、i bPerforming Clarke transformation and Park transformation to obtain a stator current D axis component i in a synchronous rotation coordinate system DAnd stator current Q axis component i Q；
The position angle theta of the motor rotor is collected through a position sensor (a rotary transformer), and the electrical angular velocity omega of the motor rotor is obtained through calculation r；
2) Motor parameter calculation module
The input variables of the motor parameter calculation module are as follows:
i Qthe actual value of the Q-axis current of the motor stator is obtained;
i Q0the component of Q-axis current when the change rate of the inductance is turned;
L Q0the inductance component of the Q axis under the normal temperature state (or rated temperature) is generally a measured value or a motor design given value under the normal temperature;
L D0the inductance component of the D axis under the normal temperature state (or rated temperature) is generally a measured value or a motor design given value under the normal temperature;
ψ f0the flux linkage value is a flux linkage value under a normal temperature state (or a rated temperature), and is generally a measured value or a motor design given value under the normal temperature;
t is the temperature of the magnetic steel;
rho is a curve coefficient, and is generally 0.1-0.3%;
γ tthe magnetic steel temperature coefficient can be searched from a magnetic steel handbook;
the output variables are:
L Q(i Qt) is Q-axis inductance along with i QAnd the value of the change in the temperature t,
L D(t) is the value of D-axis inductance as a function of temperature t, L D(t)＝L D0γ tt；
ψ f(t) is the value of the flux linkage as a function of temperature t,. phi f(t)＝ψ f0γ tt；
ΔL err0Is a Q-axis inductor L at normal temperature Q0And D-axis inductance L D0Difference of (d), Δ L err0＝L Q0-L D0；
Δi Q0Is Q-axis actual current i QAnd i Q0Difference between, Δ i Q0＝i Q-i Q0；
3) Torque current calculation module
The torque current calculation module input variables are as follows:
T *setting torque for the motor;
ψ f0the flux linkage value of the motor is in a normal temperature state;
ΔL err0is an initial value L of the Q-axis inductance Q0And D-axis inductance initial value L D0The difference between the two;
Δi Q0is Q-axis actual current i QAnd i Q0The difference between them;
t is the temperature of the magnetic steel;
rho is a curve coefficient;
γ tmagnetic steel temperature coefficient;
U Smaxin order to allow maximum amplitude of phase voltage for inverter, the control method
The output variables are as follows:
the torque current calculation module is used for setting the torque T according to the input motor *Obtaining the D-axis current under the maximum torque current ratio (MTPA) calculation method through the maximum torque current ratio (MTPA) calculation method
D-axis gives current:
wherein the content of the first and second substances,
When the motor operates in a weak magnetic region (generally, a non-weak magnetic region below a rated rotating speed and a weak magnetic region above the rated rotating speed), firstly, a D-axis and a Q-axis given reference voltage fed back by a current feedforward decoupling calculation module are utilized to calculate the amplitude U of the given reference voltage S，U SAnd the maximum allowable phase voltage amplitude U of the inverter SmaxIs subjected to PI regulation, the regulator output is
q-axis set current
When i is Q＜i Q0When the temperature of the water is higher than the set temperature,
when i is Q≥i Q0When the temperature of the water is higher than the set temperature,
4) current feedforward decoupling calculation module
The input parameters of the current feedforward decoupling calculation module are as follows:
Δu Dgiven value for D-axis current
similarly, Δ u QGiven value for Q-axis current
given reference voltage output by current feedforward decoupling calculation module
The control method of the built-in permanent magnet synchronous motor solves the problems that the existing motor control algorithm is easily influenced by parameter change, has poor dynamic performance, is complex in algorithm and the like; the method can ensure the stable operation of the built-in permanent magnet synchronous motor, and the control method is simple and effective, high in precision and strong in usability.
1) The invention carries out on-line calculation on the torque current, carries out real-time correction according to the dynamic parameters of the motor, obtains a current calculation model containing more accurate motor parameter information, further calculates to obtain the torque current by utilizing the model, and can carry out real-time correction on the torque current at low speed and high speed so as to realize accurate torque current control. The algorithm can enable the motor to operate at a more accurate working point, and has good parameter robustness and dynamic response characteristics.
2) On the basis of a traditional permanent magnet synchronous motor vector control algorithm, motor parameters are fitted, torque current is accurately calculated and distributed, and the accurate control of the built-in permanent magnet synchronous motor is realized by utilizing the calculated torque current.
3) The precise calculation control of the reference voltage is realized in the current feedforward decoupling calculation module according to the change condition of the motor parameters (permanent magnet flux linkage, D-axis inductance and Q-axis inductance), and the motor control precision is improved.
4) Compared with the existing method, the method has the functions of dynamically adjusting the motor parameters and accurately calculating the torque current, improves the accuracy of the given voltage of the motor, has good parameter robustness, does not need complicated steps of signal injection, signal extraction and the like, simplifies the method for controlling the torque current, does not need to consider the influence of system bandwidth, and has simple algorithm, high calculation speed and good dynamic performance.
Drawings
Fig. 1 is a control block diagram of an improved method of an interior permanent magnet synchronous motor according to the present invention.
Detailed Description
The control method of the built-in permanent magnet synchronous motor comprises the following steps of dividing the control method into 4 modules (shown in figure 1) which are respectively a
1) sampling calculation module
Collecting DC bus voltage U of inverter dcAnd motor stator current i a、i b(ii) a For stator current i a、i bPerforming Clarke transformation and Park transformation to obtain a stator current D axis component i in a synchronous rotation coordinate system DAnd stator current Q axis component i Q；
The position angle theta of the motor rotor is collected through a position sensor (a rotary transformer), and the electrical angular velocity omega of the motor rotor is obtained through calculation r；
2) Motor parameter calculation module
The motor parameter calculation module is mainly a functional module for calculating parameters such as motor flux linkage, inductance and the like in real time;
the motor parameter calculation module is specifically shown in fig. 1, and input variables thereof are:
i Qthe actual value of the Q-axis current of the motor stator is obtained;
i Q0the component of Q-axis current when the change rate of the inductance is turned;
L Q0the inductance component of the Q axis under the normal temperature state (or rated working condition) is generally a measured value or a motor design given value under the normal temperature;
L D0the inductance component of the D axis under the normal temperature state (or rated working condition) is generally a measured value or a motor design given value under the normal temperature;
ψ f0the flux linkage value is a flux linkage value under a normal temperature state (or a rated working condition), and is generally a measured value or a motor design given value under the normal temperature;
t is the magnetic steel temperature, which is a value obtained by embedding a temperature sensor in the motor stator at present; the temperature change of the motor magnetic steel is relatively smooth, so that the motor magnetic steel can be regarded as a fixed value in a short time;
rho is a curve coefficient, and an approximate value is obtained by fitting a curve by adopting a finite element analysis method under the Ansoft environment, wherein the approximate value is generally 0.1-0.3%;
γ tthe magnetic steel temperature coefficient can be searched from a magnetic steel handbook;
the output variables are:
L Q(i Qt) is Q-axis inductance along with i QAnd the value of the temperature t change;
L D(t) is the value of the D-axis inductance as a function of temperature t;
ψ f(t) is the value of the flux linkage as a function of temperature t;
ΔL err0is a Q-axis inductor L at normal temperature Q0And D-axis inductance L D0A difference of (d);
Δi Q0is Q-axis actual current i QAnd i Q0The difference between them;
the three motor parameters needed in the control of the permanent magnet synchronous motor are a permanent magnet flux linkage, a quadrature axis inductance and a direct axis inductance respectively.
The permanent magnet is embedded in the D-axis magnetic circuit in the permanent magnet synchronous motor, so that the D-axis magnetic flux needs to penetrate through the iron core and the air gap as well as the permanent magnet, the Q-axis magnetic flux only needs to penetrate through the iron core and the air gap, and the magnetic permeability of the permanent magnet is close to that of air due to the fact that the magnetic permeability of the iron core is high, the magnetic resistance of the D-axis magnetic circuit is larger than that of the Q-axis magnetic circuit, and therefore Q-axis inductance L is caused QInductance L greater than D axis D. In addition, the Q-axis magnetic circuit is more easily saturated than the D-axis magnetic circuit, and therefore, with the Q-axis current i QIncrease of L QWill be significantly reduced, and L DCurrent i along D axis DThe variation of (c) is relatively small.
Acquiring a motor flux linkage and a quadrature-direct axis inductance by adopting a finite element analysis method in an Ansoft environment;
wherein the direct axis inductance and the flux linkage are approximately constant; the quadrature axis inductance is greatly influenced by the quadrature axis current and has a nonlinear relation, and an approximate fitting curve is as follows:
in the above formula, when the Q-axis current is i QWhen the temperature is small, the Q-axis magnetic circuit does not enter a saturation state, so the quadrature axis inductance is basically a constant and is a constant which slowly changes along with the temperature change; with i being QIncreasing the Q-axis magnetic circuit to saturation, decreasing the quadrature axis inductance, and increasing the turning point i QThe value is denoted as i Q0；
The permanent magnet flux linkage is influenced by the temperature of the magnetic steel, and the AC-DC axis inductance is also influenced by the temperature of the magnetic steel and the AC-DC axis current. The dynamic parameters of the motor adopting a finite element analysis method in an Ansoft environment can be expressed as follows:
for D axis inductance L DCurrent i along D axis DHas small change, is obvious only along with the change of the temperature, and has specific D-axis inductance L DThe curve with temperature is given by:
L D(t)＝L D0γ tt
magnetic linkage psi fThe curve with temperature is given by:
ψ f(t)＝ψ f0γ tt
q-axis inductor L QThe curves are expressed as follows:
delta L for inductance difference between Q axis and D axis errExpressed, the expression formula is as follows:
Δi Q0representing Q-axis current i QAnd i Q0The difference between them, the expression is as follows:
Δi Q0＝i Q-i Q0
ΔL err0represents the initial value L of the Q-axis inductance Q0And D-axis inductance initial value L D0The difference, the expression is as follows:
ΔL err0＝L Q0-L D0
3) torque current calculation module
The torque current calculation module is mainly a module for calculating the D-axis given current and the Q-axis given current in real time according to the given torque;
the input variables are as follows:
T *setting torque for the motor;
ψ f0the flux linkage value of the motor is under the normal temperature state (or rated working condition);
ΔL err0is an initial value L of the Q-axis inductance Q0And D-axis inductance initial value L D0The difference between the two;
Δi Q0is Q-axis actual current i QAnd i Q0The difference between them;
t is the temperature of the magnetic steel;
rho is a curve coefficient;
γ tis the temperature coefficient of the magnetic steel;
U Smaxin order to allow maximum amplitude of phase voltage for inverter, the control method
The output variables are as follows:
the torque current calculation module is used for setting the torque T according to the input motor *Obtaining the D-axis current under the maximum torque current ratio (MTPA) calculation method through the maximum torque current ratio (MTPA) calculation method
wherein the content of the first and second substances,
When the motor operates in a weak magnetic region (generally, a non-weak magnetic region below a rated rotating speed and a weak magnetic region above the rated rotating speed), firstly, a D-axis and a Q-axis given reference voltage fed back by a current feedforward decoupling calculation module are utilized to calculate the amplitude U of the given reference voltage S，U SAnd the maximum allowable phase voltage amplitude U of the inverter SmaxIs subjected to PI regulation, the regulator output is
the D-axis and Q-axis given reference voltage amplitude expression fed back by the current feedforward decoupling calculation module is as follows:
current of Q axis
for a given electromagnetic torque T of the machine *And motor stator D-axis current
In the above formula fIs a permanent magnet flux linkage; l is D，L QActual values of D-axis and Q-axis inductors are respectively obtained; p is the number of pole pairs;
if a more accurate Q-axis current is to be obtained
simplifying the above formula, the expression can be obtained as follows:
when i is Q＜i Q0And then, the given value expression of the stator Q-axis current is as follows:
when i is Q≥i Q0And then, the given value expression of the stator Q-axis current is as follows:
in the above formula, the parameter psi f0、ΔL err0、Δi Q0、γ tT can be obtained from module 2;
as can be seen from the above formula, the temperature t of the magnetic steel is generally a slow variation, and the current is in the Q axis
4) Current feedforward decoupling calculation module
The input parameters of the current feedforward decoupling calculation module are as follows:
the expression of the current feedforward decoupling calculation module is as follows:
Δu Dgiven value for D-axis current
similarly, Δ u QGiven value for Q-axis current And Q-axis current feedback value i QThe difference value is output through a result output by a PI regulator, namely Q-axis current closed-loop regulation output;
substituting the module input variables into the expression to obtain the expression as follows:
given reference voltage output by current feedforward decoupling calculation module
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