Control method of permanent magnet synchronous motor

文档序号：1523761 发布日期：2020-02-11 浏览：12次中文

阅读说明：本技术 永磁同步电机的控制方法 (Control method of permanent magnet synchronous motor ) 是由张瑞峰柴璐军王晓妮杨高兴詹哲军梁海刚贺志学于 2019-10-29 设计创作，主要内容包括：本发明涉及交流电机的控制方法,具体为永磁同步电机的控制方法。解决现有永磁同步电机的控制方法中因使用的电机参数不准确造成电机输出的转矩精度和电机运行效率被影响的问题。该控制方法通过电机定子温度T,使用在线查表得到定子电阻Rs(T)；通过电机定子温度T、电流幅值Is、电流矢量角β,使用在线查表得到定子电感Ld(T)和Lq(T)；使用磁链观测模型实时计算出磁链值Ψf(Tr),从而提高了电机控制和解耦的准确性；利用转矩闭环的输出结果重新分配了给定的定子电流,维持了永磁同步电机按照较优的控制轨迹运行,降低了电机的发热和损耗。实现了电机的解耦控制、增强了电机控制系统的鲁棒性。(The invention relates to a control method of an alternating current motor, in particular to a control method of a permanent magnet synchronous motor. The problem that the torque precision of motor output and the motor operation efficiency are influenced due to inaccurate motor parameters in the existing control method of the permanent magnet synchronous motor is solved. The control method obtains the stator resistance through the temperature T of the motor stator by using an online table look-up R s (T) (ii) a Through the temperature T and the current amplitude of the stator of the motor I s Current vector angle β Obtaining stator inductance using online table lookup L d (T) And L q (T) (ii) a Real-time calculation of flux linkage values using flux linkage observation models Ψ f (T r ) Therefore, the accuracy of motor control and decoupling is improved; the given stator current is redistributed by utilizing the output result of the torque closed loop, the permanent magnet synchronous motor is maintained to run according to a better control track, and the heating and the loss of the motor are reduced. The decoupling control of the motor is realized, and the robustness of a motor control system is enhanced.)

1. The control method of the permanent magnet synchronous motor is characterized in that a control block diagram of the control method comprises a rotary transformer module (1), a temperature sensor module (2), a stator resistance calculation module (3), a Clark conversion module (4), a Park conversion module (5), a stator inductance calculation table look-up module (6), a permanent magnet flux linkage calculation module (7), a torque calculation module (8), a current calculation module (9), a given current generation module (10), a robust decoupling controller module (11), a PWM modulation module (12) and a three-phase inverter bridge module (13);

1) rotary transformer module

The rotary transformer is arranged on the permanent magnet synchronous motor, the rotor position theta of the permanent magnet synchronous motor is obtained through measurement of the rotary transformer, and the rotating speed w of the permanent magnet synchronous motor is obtained through differentiation of the rotor position theta _e；

2) Temperature sensor module

A temperature sensor is embedded in the motor stator, and the real-time stator temperature T of the motor is obtained by the temperature sensor;

3) stator resistance calculation module

Motor stator resistance R caused by motor temperature change _sTesting and drawing a temperature resistance comparison table of the motor stator, acquiring a real-time temperature value T of the stator through a temperature sensor, and acquiring a stator resistor R by inquiring the temperature resistance comparison table of the motor stator _s(T)；

4) Clark conversion module

Collecting two-phase stator current i _a、i _bObtaining stator current i through Clark conversion _α、i _β；

5) Park conversion module

Stator current i _α、i _βObtaining the current i under the d-q static coordinate system through Park conversion _d、i _q；

6) Stator inductance calculation table look-up module

Stator inductance L _dAnd L _qWith the motor stator temperature T and the amplitude I of the stator current _SAnd phase β of stator current _SThree variables are related;

firstly, the stator inductance L is manufactured at different temperature points within a certain temperature interval _d、L _qWith I _SAnd β _SA table of changes;

then using the real-time collected stator temperature T and the amplitude I of the stator current _SAnd phase β of stator current _SObtaining the stator inductance L by looking up the table _d(T)、L _q(T)；

7) Permanent magnet flux linkage calculation module

The input of the permanent magnet flux linkage calculation module is as follows: current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), stator voltage u 'of the last calculation cycle' _d，u’ _qPermanent magnet flux linkage psi calculated in the previous calculation cycle _f’(T _r) Rotational speed w _e(ii) a Output Ψ of the permanent magnet flux linkage calculation Module _f(T _r) The calculation method is as follows:

wherein: k _{p_Ψf}And K _{i_Ψf}Is a control parameter that is a function of,

debugging to obtain K _{p_Ψf}And K _{i_Ψf}The process of (2) is as follows: given K _{i_Ψf}A smaller parameter (e.g., 0.001), the parameter K is adjusted first _{p_Ψf}Psi making the output derived _f(T _r) In a state of constant amplitude oscillation, then the parameter K is adjusted _{i_Ψf}To make the output Ψ _f(T _r) Convergence, parameter K obtained at this time _{p_Ψf}And K _{i_Ψf}Is a control parameter;

8) torque calculation module

The input to the torque calculation module is the current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), rotational speed w _e，Ψ _f(T _r)；

Output of torque computing module-electromagnetic torque T _ebThe following calculation formula is obtained:

T _ex1＝1.5n _pi _q[(L _d(T)-L _q(T))i _d]

in the formula, n _pIs the number of pole pairs of the motor;

T _ex2＝1.5n _pi _q[(L _d(T ₀)-L _q(T ₀))i _d]

in the formula, L _d(T ₀) And L _q(T ₀) The values of the stator inductances under rated operating conditions are respectively;

T _ex＝T _ex1-T _ex2

T _est＝1.5n _pi _q[ψ _f(T _r)+(L _d(T ₀)-L _q(T ₀))i _d]

T _eb＝T _ex+T _est

9) current calculation module

Target torque T ^* _eAfter amplitude limiting and ramp processing, the given torque T is obtained ^* _e1；

T ^* _e1、T _ebStator inductance L _d(T), stator inductance L _q(T)、Ψ _f(T _r) And n _pIs the input of the current calculation module;

given torque T ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β;

T ^* _e1and T _ebThe difference of (a) is output as delta β through a PI regulator;

the final current angle β is obtained ₁Calculated by the following formula:

β ₁＝β+Δβ

10) given current generation module

The input of the given current generation module is a given current value I ^*And current angle β ₁；

The calculation process is as follows:

11) robust decoupling controller

The input parameter of the robust decoupling controller is current i _d ^*、i _q ^*、i _d、i _qStator resistor R _s(T), stator inductance L _d(T) and L _q(T), permanent magnet flux linkage Ψ _f(T _r) And a rotational speed w _eThe output parameter is the stator voltage u _d、u _q；

Intermediate variable u of control algorithm _d1、u _q1The calculation process is as follows:

in the formula, β _xIs a control parameter, which is expressed as follows:

β _x＝β _b×f _kx

in the formula, β _bIs a reference value of a control parameter, selected between 0.1 and 1.0, f _kxIs the switching frequency of the inverter;

intermediate variable u of control algorithm _d2、u _q2The calculation process is as follows:

in the formula, delta _d、δ _qThe calculation formula of (a) is as follows:

in the formula, lambda is a control parameter, and the control parameter lambda is selected by adopting a trial and error method; i.e. i _d1、i _q1As intermediate variables in the algorithmic process, i _d1、i _q1The calculation formula of (a) is as follows:

wherein, delta' _d、δ’ _qIs the variable calculated in the last calculation period (or called the last beat);

voltage u _d、u _qThe calculation process of (2) is as follows:

K _Ris a damping coefficient;

12) PWM modulation module

PWM modulation moduleIs a stator voltage u _d、u _qDc bus voltage u _dcRotational speed w _eAnd an angle θ; the output of the PWM modulation module is 6 paths of PWM waves, and the three-phase inverter bridge module is driven to work.

2. The control method of the permanent magnet synchronous motor according to claim 1, wherein in 6) the stator inductance calculation look-up table module:

considering i _qAt 0, the program is computationally problematic, so that the denominator is given a particularly small number k _α。

3. The control method of the permanent magnet synchronous motor according to claim 2, wherein in 6) the stator inductance calculation look-up table module: amplitude I of stator current _SAnd phase β of stator current _SRespectively low-pass filtering to obtain filtered values I _SLPFAnd β _SLPF。

4. The control method of the permanent magnet synchronous motor according to claim 2, wherein in 6) the stator inductance calculation look-up table module: the temperature interval is the interval of [ -30 ℃, 160 ℃ ] and the temperature values of each integral multiple of ten are taken as the temperature points, so that in the interval of [ -30 ℃, 160 ℃ ], twenty temperature points are present: -30 ℃, 20 ℃, 10 ℃, 0 ℃, 10 ℃, 20 ℃, … …, 150 ℃ and 160 ℃.

5. The control method of the permanent magnet synchronous motor according to claim 3, wherein in 6) the stator inductance calculation look-up table module: the temperature interval is the interval of [ -30 ℃, 160 ℃ ] and the temperature values of each integral multiple of ten are taken as the temperature points, so that in the interval of [ -30 ℃, 160 ℃ ], twenty temperature points are present: -30 ℃, 20 ℃, 10 ℃, 0 ℃, 10 ℃, 20 ℃, … …, 150 ℃ and 160 ℃.

6. The control method of the permanent magnet synchronous motor according to claim 4, wherein the process of making the table is: the tested permanent magnet synchronous motor and the counter-dragging motor are coaxial or connected through a gear box, the counter-dragging motor operates below a rated rotating speed, and different I of the permanent magnet synchronous motor is given under the condition that the rotating speed is stable and the temperature of a stator is at a certain temperature point _S，I _S>0 and β _S，90°<β _S<180 DEG, measured by high frequency injection method, of different I _SAnd β _SCorresponding motor stator inductance L _d、L _q(ii) a Changing the temperature of the stator to obtain a plurality of groups of stator inductances L at different temperature points _d、L _qWith I _SAnd β _SA table of changes.

7. The control method of a permanent magnet synchronous motor according to claim 5, wherein the process of making a table is: the tested permanent magnet synchronous motor and the counter-dragging motor are coaxial or connected through a gear box, the counter-dragging motor operates below a rated rotating speed, and different I of the permanent magnet synchronous motor is given under the condition that the rotating speed is stable and the temperature of a stator is at a certain temperature point _SLPF，I _SLPF>0 and β _SLPF，90°<β _SLPF<180 DEG, measured by high frequency injection method, of different I _SLPFAnd β _SLPFCorresponding motor stator inductance L _d、L _q(ii) a Changing the temperature of the stator to obtain a plurality of groups of stator inductances L at different temperature points _d、L _qWith I _SLPFAnd β _SLPFA table of changes.

8. The control method of the permanent magnet synchronous motor according to claim 6, wherein in 6) the stator inductance calculation look-up table module: the table lookup procedure is as follows: when the stator temperature T acquired in real time is not equal to the temperature value of any temperature point, two temperature points T closest to the stator temperature T are selected _x、T _x+10Stator inductance L _d、L _qWith I _SAnd β _SUsing the changed table as a look-up tableA table and a second table; when the stator temperature T acquired in real time is equal to the temperature value of a certain temperature point, selecting the temperature point T equal to the stator temperature T _xStator inductance L _d、L _qWith I _SAnd β _STable of changes, temperature point T adjacent to temperature increasing side of the temperature point _x+10Stator inductance L _d、L _qWith I _SAnd β _SA changed table, a first table and a second table used as table lookup; according to the amplitude I of the collected stator current _SAnd phase β of stator current _SLooking up L in the first table _d1(T) and L _q1(T), finding L in the second table _d2(T) and L _q2(T); l is obtained as follows _d(T) and L _q(T)：

9. The control method of the permanent magnet synchronous motor according to claim 7, wherein in 6) the stator inductance calculation look-up table module: the table lookup procedure is as follows: when the stator temperature T acquired in real time is not equal to the temperature value of any temperature point, two temperature points T closest to the stator temperature T are selected _x、T _x+10Stator inductance L _d、L _qWith I _SLPFAnd β _SLPFThe changed tables are used as a first table and a second table for table lookup; when the stator temperature T acquired in real time is equal to the temperature value of a certain temperature point, selecting the temperature point T equal to the stator temperature T _xStator inductance L _d、L _qWith I _SLPFAnd β _SLPFTable of changes, temperature point T adjacent to temperature increasing side of the temperature point _x+10Stator inductance L _d、L _qWith I _SLPFAnd β _SLPFA changed table, a first table and a second table used as table lookup; according to the collected I _SLPFAnd β _SLPFLooking up L in the first table _d1(T) and L _q1(T), finding L in the second table _d2(T) and L _q2(T); according to the followingThe following formula gives L _d(T) and L _q(T)：

10. Method for controlling a permanent magnet synchronous machine according to any of claims 1-9, characterized in that, 9) in the current calculation module, a torque T is given ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β are calculated as follows:

obtaining a per unit value base value t through operation _ebAnd i _bxWherein i _bxIs the per unit value base value of the current, passing through i _bx＝ψ _f(T _r)/(L _q(T)-L _d(T)) calculating; t is t _ebIs a per unit value base value of torque, which can be expressed by t _eb＝n _pψ _f(T _r)i _bxCalculating to obtain;

given torque

in per unit value, the relationship between torque and current of the control algorithm is expressed as:

A given current value I ^*By the formula

current angle β passing through

in view of

Technical Field

The invention relates to a control method of a motor, in particular to a control method of a permanent magnet synchronous motor.

Background

The permanent magnet synchronous motor has the advantages of high efficiency, energy conservation, high power density and the like, and is widely applied to the field of rail transit. For a permanent magnet synchronous motor, the most important performance requirement is to generate accurate torque and realize high-efficiency control under various environments, and one of the most important factors influencing the torque precision and the high-efficiency control of the permanent magnet motor is the change of motor parameters in the motor operation process, which causes the mismatching of a motor control algorithm and a controlled motor. The change of motor parameters is mainly caused by the magnetic saturation effect of an iron core caused by the change of the working temperature of the motor and the stator current, thereby causing the stator inductance L in the motor parameters _d、L _qStator resistor R _sAnd a permanent magnet flux linkage Ψ _fA change in (c). The traditional vector control method is widely used in permanent magnet synchronous motor control, but does not consider temperature to motor parameter R _s、Ψ _fAnd iron core saturation effect pair L _d、L _qThe accuracy of the torque output from the motor and the efficiency of the motor operation will be greatly affected.

Disclosure of Invention

The invention solves the problem that the torque precision of the motor output and the motor operation efficiency are influenced due to inaccurate motor parameters in the existing control method of the permanent magnet synchronous motor, and provides the control method of the permanent magnet synchronous motor. Meanwhile, on the basis of accurately determining the motor parameters, a robust decoupling control method for the permanent magnet synchronous motor is provided, decoupling control of the motor is achieved, and robustness of a motor control system is enhanced.

The invention is realized by adopting the following technical scheme: the control block diagram of the optimization control method of the permanent magnet synchronous motor comprises a rotary transformer module, a temperature sensor module, a stator resistance calculation module, a Clark conversion module, a Park conversion module, a stator inductance calculation table look-up module, a permanent magnet flux linkage calculation module, a torque calculation module, a current calculation module, a given current generation module, a robust decoupling controller module, a PWM (pulse width modulation) module and a three-phase inverter bridge module;

1) rotary transformer module

2) Temperature sensor module

A temperature sensor is embedded in the motor stator, and the real-time stator temperature T of the motor is obtained by the temperature sensor;

3) stator resistance calculation module

4) Clark conversion module

Collecting two-phase stator current i _a、i _bObtaining stator current i through Clark conversion _α、i _β；

5) Park conversion module

Stator current i _α、i _βObtaining the current i under the d-q static coordinate system through Park conversion _d、i _q；

6) Stator inductance calculation table look-up module

StatorInductor L _dAnd L _qWith the motor stator temperature T and the amplitude I of the stator current _SAnd phase β of stator current _SThree variables are related;

firstly, the stator inductance L is manufactured at different temperature points within a certain temperature interval _d、L _qWith I _SAnd β _SA table of changes;

7) Permanent magnet flux linkage calculation module

The input of the permanent magnet flux linkage calculation module is as follows: current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), stator voltage u 'of the last calculation cycle (or title to last beat)' _d，u’ _qThe permanent magnet flux linkage Ψ calculated in the previous calculation cycle (or referred to as the previous beat) _f’(T _r) Rotational speed w _e. Output Ψ of the permanent magnet flux linkage calculation Module _f(T _r) The calculation method is as follows:

wherein: k _{p_Ψf}And K _{i_Ψf}Is a control parameter that is a function of, respectively representing the estimated current values, T being the acquisition time, T _rRepresents the actual operating temperature of the permanent magnet;

And

calculated by the following formula:

8) torque calculation module

The input to the torque calculation module is the current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), rotational speed w _e，Ψ _f(T _r)；

Output of torque computing module-electromagnetic torque T _ebThe following calculation formula is obtained:

T _ex1＝1.5n _pi _q[(L _d(T)-L _q(T))i _d]

in the formula, n _pIs the pole pair number of the motor.

T _ex2＝1.5n _pi _q[(L _d(T ₀)-L _q(T ₀))i _d]

In the formula, L _d(T ₀) And L _q(T ₀) The values of the stator inductances in the nominal operating mode are in each case.

T _ex＝T _ex1-T _ex2

T _est＝1.5n _pi _q[ψ _f(T _r)+(L _d(T ₀)-L _q(T ₀))i _d]

T _eb＝T _ex+T _est

9) Current calculation module

Target torque T ^* _eAfter amplitude limiting and ramp processing, the given torque T is obtained ^* _e1；

T ^* _e1、T _ebStator inductance L _d(T), stator inductance L _q(T)、Ψ _f(T _r) And n _pIs the input of the current calculation module;

given torque T ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β (shown in FIG. 3);

given torque T ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β are calculated as follows:

Given torque

And its per unit value t _enPassing through type

Represents; electric current

And its per unit value i _dnCan pass through

Represents; electric current

And its per unit value i _qnCan pass through

Represents the current of

And current

Is to calculate I ^*An intermediate variable of (d);

in per unit value, the relationship between torque and current of the control algorithm is expressed as:

by commanding a given torque

Becomes per unit value t _enIn a format of, and then by a formula

Solving to obtain current

Per unit value of i _dnAnd finally, the formula of

Given current can be calculated Electric current

Per unit value of i _qnCan be represented by the formula t _en＝i _qn(1-i _dn) Is calculated to be t at this time _enAnd i _dnIs a known amount, and then a formula

Given current can be calculated

A given current value I ^*By the formula

Calculating to obtain;

current angle β passing through Calculating to obtain;

in view of

At 0, the program is computationally problematic, so that the denominator is given a particularly small number k _b，k _bMay be equal to 0.0000001;

T ^* _e1and T _ebThe difference is output to be delta β through a PI regulator, delta β is a compensation value of a given current angle, and the given current angle is corrected by identifying real-time torque and comparing the real-time torque with the given torque;

the final current angle β is obtained ₁Calculated by the following formula:

β ₁＝β+Δβ

10) given current generation module

The input of the given current generation module is a given current value I ^*And current angle β ₁；

The calculation process is as follows:

11) robust decoupling controller

Intermediate variable u of control algorithm _d1、u _q1The calculation process is as follows:

in the formula, β _xIs a control parameter, control parameter β _xVarying with modulation strategy, control parameter β _xProportional to the switching frequency, which is expressed as follows:

β _x＝β _b×f _kx

in the formula, β _bIs a reference value of a control parameter, selected between 0.1 and 1.0, f _kxIs the switching frequency of the inverter;

u is calculated by the above control algorithm _d1、u _q1The decoupling control of the permanent magnet synchronous motor is realized;

intermediate variable u of control algorithm _d2、u _q2The calculation process is as follows:

in the formula, delta _d、δ _qIs a key part of a robust controller, and the calculation formula is as follows:

in the formula, lambda is a control parameter, and the control parameter lambda is selected by a trial and error method, and can be 80; i.e. i _d1、i _q1As intermediate variables in the algorithmic process, i _d1、i _q1The calculation formula of (a) is as follows:

wherein, delta' _d、δ’ _qIs the variable calculated in the last calculation period (or called the last beat);

voltage u _d、u _qThe calculation process of (2) is as follows:

in order to enhance the stability of the control system and realize control decoupling, the term R is respectively added to the dq axis _S(T)×k _R×i _dAnd R _S(T)×k _R×i _q+Ψ _f(T _r)w _e，K _RThe damping coefficient is 0.9;

12) PWM modulation module

The input of the PWM modulation module is a stator voltage u _d、u _qDc bus voltage u _dcRotational speed w _eAnd an angle θ; the output of the PWM modulation module is 6 paths of PWM waves, and the three-phase inverter bridge module is driven to work.

The invention has the following beneficial effects:

(1) the invention passes the temperature T and the current amplitude I of the stator of the motor _sThe current vector angle β is looked up on line to obtain the accurate stator resistance R of the motor parameter _s(T), stator inductance L _d(T) and L _q(T) calculating the flux linkage value Ψ in real time using a flux linkage observation model _f(T _r) Detection equipment for the temperature of the rotor is omitted, and the accuracy of motor control and decoupling is improved; and the given stator current is redistributed by utilizing the output result of the torque closed loop, so that the permanent magnet synchronous motor is kept to run in a better track, and the heating and the loss of the motor are reduced.

(2) By using a robust decoupling control method in the current loop, the anti-interference performance of system control is improved, and decoupling control of the permanent magnet synchronous motor is realized.

Drawings

FIG. 1 is a control block diagram of the control method of the present invention;

FIG. 2 is a block diagram of a flow of a stator inductance calculation look-up table module;

FIG. 3 is a control block diagram of a current calculation module;

FIG. 4 is a control block diagram of a robust decoupling controller;

fig. 5 is a schematic diagram of a segment modulation algorithm.

Detailed Description

The control block diagram (as shown in fig. 1) of the control method of the permanent magnet synchronous motor comprises a rotary transformer module 1, a temperature sensor module 2, a stator resistance calculation module 3, a Clark conversion module 4, a Park conversion module 5, a stator inductance calculation look-up table module 6, a permanent magnet flux linkage calculation module 7, a torque calculation module 8, a current calculation module 9, a given current generation module 10, a robust decoupling controller module 11, a PWM modulation module 12 and a three-phase inverter bridge module 13;

1) rotary transformer module

2) Temperature sensor module

A temperature sensor is embedded in the motor stator, and the real-time stator temperature T of the motor is obtained by the temperature sensor;

3) stator resistance calculation module

4) Clark conversion module

Collecting two-phase stator current i _a、i _bObtaining stator current i through Clark conversion _α、i _β；

5) Park conversion module

Stator current i _α、i _βObtaining the current i under the d-q static coordinate system through Park conversion _d、i _q；

6) Stator inductance calculation table look-up module

The change of the stator current can cause the magnetic saturation effect of the stator core, and the stator inductance L is changed along with the change of the d-axis current and the q-axis current _d、L _qWill change and the stator temperature T of the motor will also have an influence on the stator inductance. To getTo a more accurate stator inductance parameter L _dAnd L _qObtaining stator inductance L by using table look-up method _dAnd L _q；

Stator inductance L _dAnd L _qWith the motor stator temperature T and the amplitude I of the stator current _SAnd phase β of stator current _SThree variables are related (as shown in fig. 2);

wherein:

considering i _qAt 0, the program is computationally problematic, so that the denominator is given a particularly small number k _α，k _αMay be equal to 0.0000001;

further, the amplitude I of the stator current _SAnd phase β of stator current _SRespectively low-pass filtering to obtain filtered values I _SLPFAnd β _SLPF。

Firstly, the stator inductance L is manufactured at different temperature points within a certain temperature interval _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) The changed tables (the number of the tables is consistent with the number of the temperature points set in the temperature interval, and the table corresponding to each temperature point reflects the stator inductance L _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) Content of the change); in specific implementation, the temperature range is-30 ℃ and 160 DEG C]Interval, and taking the temperature value of integral multiple of each ten as the temperature point, so that the temperature is between minus 30 ℃ and 160 DEG C]Interval, there are twenty temperature points: -30 ℃, -20 ℃, -10 ℃, 0 ℃, 10 ℃, 20 ℃, … …, 150 ℃, 160 ℃; the specific process of making the table is as follows: the tested permanent magnet synchronous motor and the counter-dragging motor are coaxial or connected through a gear box, the counter-dragging motor operates below the rated rotating speed, and different current instructions I of the permanent magnet synchronous motor are given under the conditions that the rotating speed is stable and the temperature of a stator is at a certain temperature point (taking-20 ℃ as an example) _S，I _S>0 and β _S，90°<β _S<180°(or I) _SLPF，I _SLPF>0 and β _SLPF，90°<β _SLPF<180 degree (Current i) ^* _d、i ^* _q) By high frequency injection of different I _SAnd β _S(or I) _SLPFAnd β _SLPF) Corresponding motor stator inductance L _d、L _q(ii) a Changing the temperature of the stator to obtain a plurality of groups of stator inductances L at different temperature points _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) A table of changes.

Then using the real-time collected stator temperature T and the amplitude I of the stator current _SAnd phase β of stator current _S(or I) _SLPFAnd β _SLPF) Obtaining real-time stator inductance L by querying the table _d(T)、L _q(T); the table lookup procedure is as follows: when the stator temperature T acquired in real time is not equal to the temperature value of any temperature point, two temperature points T closest to the stator temperature T are selected _x、T _x+10Stator inductance L _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) The first table and the second table used as the table look-up table (e.g., stator temperature T of 23 deg.C, selected temperature point T) _x20 ℃ and T _x+10Table at 30 ℃ as first and second tables); when the stator temperature T acquired in real time is equal to the temperature value of a certain temperature point, selecting the temperature point T equal to the stator temperature T _xStator inductance L _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) Table of changes, temperature point T adjacent to temperature increasing side of the temperature point _x+10Stator inductance L _d、L _qWith I _SAnd β _S(or I) _SLPFAnd β _SLPF) A changed table, a first table and a second table used as table lookup; according to the amplitude I of the collected stator current _SAnd phase β of stator current _S(or I) _SLPFAnd β _SLPF) Looking up L in the first table _d1(T) and L _q1(T), finding L in the second table _d2(T) and L _q2(T)；L is obtained as follows _d(T) and L _q(T)：

L _d(T) and L _q(T) is the current operating condition (current temperature T, current I) _SAnd β _S(or I) _SLPFAnd β _SLPF) Motor stator inductance value.

7) Permanent magnet flux linkage calculation module

The permanent magnet material in the permanent magnet synchronous motor rotor is greatly influenced by temperature change, and the change relation between the permanent magnet flux linkage of the motor and the temperature can be expressed as

Wherein: Ψ _f(T ₀) Is the permanent magnet flux linkage psi under the rated working condition _f(T _r) Is the permanent magnet flux linkage, T, at the actual operating temperature of the motor ₀May be taken at 20 ℃ T _rIs the actual operating temperature of the permanent magnet and α is the temperature coefficient of remanence.

Because the permanent magnet of the motor is arranged on the rotor of the motor, the actual working temperature of the motor cannot be obtained, and the flux linkage value psi is obtained in real time by adopting a flux linkage observation model _f(T _r) The input of the permanent magnet flux linkage calculation module is as follows: current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), stator voltage u 'of the last calculation cycle (or title to last beat)' _d，u’ _qThe permanent magnet flux linkage Ψ calculated in the previous calculation cycle (or referred to as the previous beat) _f’(T _r) Rotational speed w _eOutput Ψ of the permanent magnet flux linkage calculation Module _f(T _r) The calculation method is as follows:

and

calculated by the following formula:

8) torque calculation module

The input to the torque calculation module is the current i _d、i _qStator resistance R _s(T), stator inductance L _d(T) and L _q(T), rotational speed w _e，Ψ _f(T _r)；

Output of torque computing module-electromagnetic torque T _ebThe following calculation formula is obtained:

T _ex1＝1.5n _pi _q[(L _d(T)-L _q(T))i _d]

in the formula, n _pIs the number of pole pairs of the motor;

T _ex2＝1.5n _pi _q[(L _d(T ₀)-L _q(T ₀))i _d]

in the formula, L _d(T ₀) And L _q(T ₀) The values of the stator inductances under rated operating conditions are respectively;

T _ex＝T _ex1-T _ex2

T _est＝1.5n _pi _q[ψ _f(T _r)+(L _d(T ₀)-L _q(T ₀))i _d]

T _eb＝T _ex+T _est

9) current calculation module

Target torque T ^* _eAfter amplitude limiting and ramp processing, the given torque T is obtained ^* _e1；

T ^* _e1、T _ebStator inductance L _d(T) and L _q(T)、Ψ _f(T _r) And n _pIs the input of the current calculation module;

given torque T ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β (shown in FIG. 3);

given torque T ^* _e1Obtaining a given current value I through a calculation module ^*And current angle β are calculated as follows:

Given torque

And its per unit value t _enCan pass through

Represents; electric current And its per unit value i _dnCan pass through

Represents; electric current

And its per unit value i _qnCan pass through

Represents the current of And current

Is to calculate I ^*An intermediate variable of (d);

in per unit value, the relationship between torque and current of the control algorithm is expressed as:

by applying a given torque

Becomes per unit value t _enIn a format of, and then by a formula

Solving to obtain current

Per unit value of i _dnAnd finally, the formula of

Given current can be calculated

Electric current

Per unit value of i _qnCan be represented by the formula t _en＝i _qn(1-i _dn) Is calculated to be t at this time _enAnd i _dnIs a known amount, and then a formula

Given current can be calculated

A given current value I ^*By the formula Calculating to obtain;

current angle β passing through

Calculating to obtain;

in view of At 0, the program is computationally problematic, so that the denominator is given a particularly small number k _b，k _bMay be equal to 0.0000001;

the final current angle β is obtained ₁Calculated by the following formula:

β ₁＝β+Δβ

10) given current generation module

The input of the given current generation module is a given current value I ^*And current angle β ₁；

The calculation process is as follows:

11) robust decoupling controller

The robust decoupling controller realizes decoupling control of the permanent magnet synchronous motor on one hand and improves the anti-interference function of motor control on the other hand, and the input parameter of the robust decoupling controller is current i _d ^*、i _q ^*、i _d、i _qStator resistor R _s(T), stator inductance L _d(T) and L _q(T), permanent magnet flux linkage Ψ _f(T _r) And a rotational speed w _eWith stator voltage u as an output parameter _d、u _q；

A robust decoupling controller is shown in fig. 4.

Intermediate variable u of control algorithm _d1、u _q1The calculation process is as follows:

in the formula, β _xIs a control parameter, control parameter β _xVarying with modulation strategy, control parameter β _xProportional to the switching frequency, which is expressed as follows:

β _x＝β _b×f _kx

in the formula, β _bIs a control parameter reference value selected from 0.1-1.0 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0; preferably 0.5), f _kxIs the switching frequency of the inverter;

u is calculated by the above control algorithm _d1、u _q1The decoupling control of the permanent magnet synchronous motor is realized;

intermediate variable u of control algorithm _d2、u _q2The calculation process is as follows:

in the formula, delta _d、δ _qIs a key part of a robust controllerThe calculation formula is as follows:

in the formula, lambda is a control parameter, and the control parameter lambda is selected by a trial and error method, and can be 80. i.e. i _d1、i _q1As intermediate variables in the algorithmic process, i _d1、i _q1The calculation formula of (a) is as follows:

wherein, delta' _d、δ’ _qIs the variable calculated in the last calculation period (or called the last beat);

voltage u _d、u _qThe calculation process of (2) is as follows:

12) PWM modulation module

The input of the PWM modulation module is a stator voltage u _d、u _qDc bus voltage u _dcRotational speed w _eAnd an angle theta. The output of the PWM modulation module is 6 paths of PWM waves, and the three-phase inverter bridge module is driven to work.

Due to the restriction of conditions such as heat dissipation, the modulation algorithm of the high-power permanent magnet synchronous motor is limited by the switching frequency, and a segmented modulation strategy combining multiple modulation modes is generally adopted. A schematic diagram of the segmented modulation strategy is shown in fig. 5.

The segmented modulation is divided into asynchronous modulation and synchronous modulation, the synchronous modulation can be divided into multiple segments under the limitation of switching frequency, and finally square wave modulation is carried out. Under square wave modulation, the voltage utilization rate is high and harmonic waves are small. In the synchronous segmented modulation algorithm, available modulation algorithms include SPWM modulation, specific subharmonic elimination PWM (SHEPWM) modulation and the like, and various modulation algorithms have advantages, disadvantages and application ranges.

The control method provided by the invention can be realized in a DSP chip, the control of the permanent magnet synchronous motor is realized by two-stage interruption, a motor control algorithm (namely, steps 1-11) is operated in one-stage interruption, and the design control period is 250 us; and operating the PWM algorithm of the motor in the other stage of interruption, wherein the interruption period is related to the operation frequency of the motor according to the current modulation strategy.

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Control method of permanent magnet synchronous motor

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