CN103872951B - Permanent magnet synchronous motor torque control method based on sliding mode flux linkage observer - Google Patents

Abstract

The invention discloses a permanent magnet synchronous motor torque control method based on a sliding mode flux observer, through a 3/2 coordinate transformation module, a sliding mode flux observer, an electromagnetic torque calculation module, a rotational speed PI regulator, a rotational speed The torque PI regulator, the flux linkage adaptive module, the expected voltage calculation module, the SVPWM module and the inverter perform direct torque control on the permanent magnet synchronous motor. Using the sliding mode flux observer module to estimate the magnitude and phase of the stator flux and the rotor speed, the given torque is obtained by the flux adaptive module to obtain the given value of the stator flux, the estimated value of the stator flux magnitude and phase, and the The given value of the chain and the output of the torque PI regulator are calculated by the expected voltage to obtain the reference value of the two-phase AC voltage on the two-phase static coordinate system, and then transformed by SVPWM to obtain the switching signal to drive the voltage source inverter to realize Direct torque control of permanent magnet synchronous motors.

Description

Torque Control Method of Permanent Magnet Synchronous Motor Based on Sliding Mode Flux Observer

technical field

The invention belongs to the field of permanent magnet motor control, in particular to a permanent magnet synchronous motor torque control system based on a sliding mode flux observer.

Background technique

Permanent magnet synchronous motors have the advantages of small size, high efficiency, easy maintenance and strong adaptability to the environment, and are widely used in many high-performance drive fields. Direct torque control has attracted much attention because of its fast torque response, simple system structure and strong robustness to parameter changes. The stator flux linkage needs to be obtained in the direct torque control of the permanent magnet synchronous motor, and the accuracy of the flux linkage signal determines the control performance of the system. Therefore, how to accurately observe the stator flux linkage is particularly important for the high-performance permanent magnet synchronous motor direct torque control speed regulation system. In traditional direct torque control, the voltage model or current model is generally used to calculate the stator flux linkage. However, in the voltage model, due to the integration of the back EMF of the stator winding, when the motor is running at low speed, the estimation accuracy of the stator flux linkage is seriously reduced, and even the system cannot work; in the current model, the rotor position needs to be known, adding additional position sensor, which will increase the cost of the control system, reduce the reliability of the system, and also limit the use of permanent magnet synchronous motors. In addition, in the direct control of the traditional hysteresis comparison, there are still shortcomings such as large torque and flux linkage fluctuations, and the switching frequency is not fixed. Moreover, when the motor is running at no load, reactive current is introduced, which leads to a decrease in the power factor of the motor. . Therefore, in order to solve the above problems, it is necessary to propose a new flux linkage observation method under the premise of increasing the switching frequency and reducing the direct axis current at no-load, so as to improve the dynamic and static performance of the permanent magnet synchronous motor direct torque control system , reliability, robustness and anti-interference ability.

Contents of the invention

Technical problem: Aiming at the deficiencies of the above-mentioned existing technologies, a permanent magnet synchronous motor torque control method based on a sliding mode flux observer is provided. On the premise of increasing the switching frequency and reducing the direct axis current at no-load, the permanent Robustness and anti-disturbance ability of direct torque control of magnetic synchronous motor.

Technical solution: permanent magnet synchronous motor torque control method based on sliding mode flux observer, through 3/2 coordinate transformation module, sliding mode flux observer, electromagnetic torque calculation module, speed PI regulator, torque PI adjustment The inverter, the flux linkage adaptive module, the expected voltage calculation module, the SVPWM module and the inverter perform direct torque control on the permanent magnet synchronous motor, including the following specific steps:

Step 1), detect the three-phase current _ia , _ib , _ic and the three-phase voltage u _a , _ub , _uc of the permanent magnet synchronous motor, and obtain the current in the two-phase static AC coordinate after the 3/2 coordinate transformation components i _α , i _β and voltage components u _α , u _β , and then send the current components i _α , i _β and voltage components u _α , u _β to the sliding mode flux observer, and send the current components i _α , i _β is sent to the electromagnetic torque calculation module;

Step 2), according to the current components i _α , i _β and voltage components u _α , u _β , the sliding mode flux linkage observer module estimates the estimated value of the stator flux linkage and stator flux phase estimates and the rotor speed estimate

Step 3), compare the given rotational speed ω ^* with the rotor speed estimate After making a difference, the given torque Te ^* is obtained after the speed PI regulator;

Step 4), according to the estimated value of the stator flux linkage size As well as the current components i _α and i _β , the electromagnetic torque calculation module obtains the actual torque Te of the motor;

Step 5), the given torque Te ^* obtains the stator flux linkage given value ψ _sref through the flux linkage adaptive module;

Step 6), after making a difference between the given torque Te ^* and the actual torque Te of the motor, the output value Δδ is obtained after the torque PI regulator;

Step 7), the output Δδ, the given value of stator flux linkage ψ _s.ref , and the estimated value of stator flux linkage and stator flux phase estimates Through the expected voltage calculation module, the two-phase AC voltage reference value on the two-phase stationary coordinate system is obtained

Step 8), according to the stator flux vector position and the two-phase AC voltage reference value After selecting the corresponding space voltage vector from the switch state table, the modulation signal is output to the inverter through the SVPWM module, and the direct torque control of the permanent magnet synchronous motor is realized through the inverter.

As a preferred version of the present invention, said step 2) includes the following specific steps:

Step 2.1), according to the current components i _α , i _β and voltage components u _α , u _β , construct a sliding mode observer to obtain the back electromotive force e _α , e _β of the motor;

Step 2.2), according to the counter electromotive force e _α and e _β , obtain the estimated position of the rotor through the rotor position calculation module

Step 2.3), according to the estimated position of the rotor Obtain the current stator flux vectors ψ _α and ψ _β through the stator flux estimation module;

Step 2.4), according to the current stator flux vectors ψ _α and ψ _β , obtain the estimated value of the stator flux through the flux observer and the rotor speed estimate

Step 2.5), according to the estimated value of the stator flux linkage Obtain the stator flux linkage phase estimation value through the flux linkage position calculation module

As an improvement of the present invention, the variable structure function of the sliding mode observer in step 2.1) is a sigmoid function.

Beneficial effects: the present invention uses sliding mode control algorithm to estimate stator flux linkage and rotor position, can accurately control stator flux linkage in real time, and realizes direct torque control of permanent magnet synchronous motor based on position sensorless control, and has the following beneficial effects:

(1) This method combines SVPWM technology and flux linkage adaptive method, so it can reduce the torque and flux linkage ripple in direct torque control, greatly increase the switching frequency to improve the current waveform, and also reduce the motor no-load Or the direct axis current component when the load is suddenly added, so as to reduce the loss of the motor and improve the efficiency of the motor;

(2) Construct a sliding mode flux observer to estimate the stator flux and rotor speed, which improves the estimation accuracy of the stator flux at low speed, thereby improving the low-speed performance of the system, while eliminating the need for a position sensor, thereby reducing the cost of the control system , which improves the reliability of the system and simplifies the system structure;

(3) For the first time, this method combines the flux adaptive method, the sliding mode flux observer and SVPWM in the direct torque control system of the permanent magnet synchronous motor, so that the control system not only retains the good dynamic and static state in the sliding mode control Performance, anti-interference ability and robustness, and also broaden the operating range of the system;

(4) The method used has a small amount of calculation and is easy to implement, which is beneficial to the engineering and practical application of the new theory.

Description of drawings

Fig. 1 is the structural block diagram of the permanent magnet synchronous motor torque control system based on the sliding mode flux observer of the present invention;

Figure 2 is a block diagram of the principle structure of the sliding mode flux observer.

detailed description

The technical solution of the present invention will be described in further detail below in conjunction with FIG. 1 and FIG. 2 .

As shown in Figure 1, the permanent magnet synchronous motor torque control system based on sliding mode flux observer in the present invention includes permanent magnet synchronous motor, 3/2 coordinate transformation, sliding mode flux observer, electromagnetic torque calculation, speed PI Regulator, Torque PI Regulator, Flux Adaptation, Expected Voltage Calculation, SVPWM Module and Inverter.

The specific implementation steps of the permanent magnet synchronous motor torque control method based on the sliding mode flux observer in the present invention are as follows:

Step 1), detect the three-phase current _ia , _ib , _ic and the three-phase voltage u _a , _ub , _uc of the permanent magnet synchronous motor, and obtain the current in the two-phase static AC coordinate after the 3/2 coordinate transformation components i _α , i _β and voltage components u _α , u _β , then send current components i _α , i _β and voltage components u _α , u _β to the sliding mode flux observer, and send current components i _α , i _β Send to the electromagnetic torque calculation module;

Step 2), according to the current components i _α , i _β and voltage components u _α , u _β , use the sliding mode flux observer module to estimate the estimated value of the stator flux linkage and stator flux phase estimates and the rotor speed estimate Its principle block diagram is shown in Figure 2, and the specific algorithm is as follows:

Step 2.1), according to the current components i _α , i _β and voltage components u _α , u _β , construct a sliding mode observer to obtain the back electromotive force e _α , e _β of the motor; among them, construct a sliding mode current observer, as follows:

The mathematical model of the permanent magnet synchronous motor is expressed in the αβ coordinate system as:

Among them, L _s is the synchronous inductance of the motor; ψ _f is the permanent magnet flux linkage; ω is the electrical angular velocity of the motor rotor; R _s is the stator resistance; e _α and e _β are the α and β axis components of the motor’s back EMF;

According to the sliding mode variable structure control theory, when the system slides on the sliding mode surface, there are:

in, is the estimated value of the current; i _s =[i _α i _β ] ^T is the actual value of the current;

In order to reduce system chattering, the sigmoid function is used instead of the switching function of the traditional sliding mode variable structure as the sliding mode variable structure function, then:

Among them, k is the sliding mode coefficient; H is the sigmoid function; with To estimate the α and β axis components of the stator current;

Define the variable structure function as follows:

Among them, S is the difference between the estimated current and the actual current; a is a real number greater than zero, which can be adjusted according to the actual situation;

Subtracting formula (3) from formula (1), the dynamic equation of the sliding mode observer can be obtained:

Among them, S _α (X) and S _β (X) are the α and β axis components of the difference between the estimated current and the actual current;

According to the existence and stability conditions of sliding mode motion, the premise that the rotor position of the motor can be estimated smoothly must meet:

but:

k＞max(|e _α |, |e _β |) (6)

Therefore, k is large enough to ensure the asymptotic stability of the sliding mode motion. When the system reaches the sliding mode surface, there are:

Substituting the above formula into formula (5) can get the counter electromotive force e _α and e _β of the motor:

Step 2.2), according to the counter electromotive force e _α and e _β , the estimated rotor position of the motor is obtained through the rotor position calculation module for:

Step 2.3), estimate the position from the rotor Combined with the current components i _α and i _β in the two-phase static coordinate system, the current stator flux vectors ψ _α and ψ _β are initially calculated by the stator flux estimation module:

Since the sliding mode current observer constructed in step 2.1) contains high-frequency components, the estimated stator flux linkage also contains high-frequency components, which need to be filtered by a low-pass filter, but the use of a low-pass filter will bring The phase delay affects the accuracy of flux linkage estimation. In order to improve the estimation accuracy of flux linkage, the present invention constructs a novel flux linkage observer;

Step 2.4), according to the current stator flux vectors ψ _α , ψ _β , obtain the estimated value of the stator flux through the flux observer and the rotor speed estimate Specific steps are as follows:

Construct a flux observer to improve the estimation accuracy of flux linkage, and use the Lyapunov theorem to analyze the stability of the flux observer, as follows:

Taking the derivative of formula (10), we can get:

Among them, ω is the electrical angular velocity of the motor rotor;

According to the above formula, the flux observer can be constructed:

Among them, l is the gain of the flux linkage observer, and its value is greater than zero; To estimate the component of the flux linkage in the αβ coordinate system; Estimate the electrical angular velocity for the rotor;

Substituting formula (7) into formula (12), we can get:

By making the difference between formula (13) and formula (11), the error equation of the flux linkage observer is obtained as:

Among them, ω is the electrical angular velocity of the motor rotor; l is the gain of the flux observer, and its value is greater than zero; To estimate the component of the flux linkage in the αβ coordinate system; Estimate the electrical angular velocity for the rotor;

Using the Lyapunov theorem to prove the stability of the flux observer, there are:

The derivative of formula (15) is:

Substituting formula (14) into formula (16), we can get:

It can be seen from formula (17) that the flux linkage observer is asymptotically stable, therefore, the estimated value of stator flux linkage can be calculated according to formula (14) and speed estimates

Step 2.5), according to the estimated value of the stator flux linkage Obtain the stator flux linkage phase estimation value through the flux linkage position calculation module

Step 3), compare the given rotational speed ω ^* with the estimated rotor speed After making a difference, the given torque Te ^* is obtained after the speed PI regulator;

Step 4), according to the estimated value of the stator flux linkage As well as the current components i _α and i _β under the two-phase static coordinates, the actual torque Te of the motor is obtained through the electromagnetic torque calculation module, as follows:

Among them, p ₀ is the number of pole pairs of the motor;

Step 5), the given torque Te ^* is obtained through the flux linkage adaptive module to obtain the given value ψ _s.ref of the stator flux linkage, as follows:

The direct-axis components ψ _sq and ψ _sd of the permanent magnet synchronous motor stator flux linkage are:

Among them, L _d and L _q are the dq axis components of the stator inductance, and i _d and i _q are the dq axis components of the stator current;

The relationship between motor torque and stator flux components is as follows:

Among them, ψ _s is the stator flux linkage, δ is the load angle;

In formula (20), let i _d =0, combined with formula (21), the given reference value ψ _sref of the stator flux linkage can be obtained as:

Step 6), after making a difference between the given torque Te ^* and the actual torque Te of the motor, the output value Δδ is obtained after the torque PI regulator;

Step 7), output Δδ, given value of stator flux linkage ψ _s.ref , estimated value of stator flux linkage and stator flux phase estimates Through the expected voltage calculation module, the two-phase AC voltage reference value on the two-phase stationary coordinate system is obtained

Step 8), according to the stator flux vector position and the two-phase AC voltage reference value After selecting the corresponding space voltage vector from the switch state table, the modulation signal is output to the inverter through the SVPWM module, and the direct torque control of the permanent magnet synchronous motor is realized through the inverter.

In the present invention, the estimation of the stator flux vector and the rotor speed adopt the sliding mode flux observer, which not only has the advantages of simple sliding mode algorithm and strong robustness, but also, compared with the traditional voltage model, the stator flux at low speed The estimation accuracy is greatly improved, and the low-speed operation performance of the motor is improved; compared with the traditional current model, no additional position sensor is needed, the cost of the control system is reduced, and the reliability of the system is improved; the given value of the stator flux linkage is obtained by the flux linkage adaptive method, Its value changes according to the size of the load, therefore, it reduces the direct axis current when the motor is running at no load or suddenly loaded with heavy load, and improves the efficiency of the motor. The invention can observe and control the stator flux linkage in real time and combine the flux linkage adaptive method and SVPWM technology, which can effectively reduce the torque and flux linkage pulsation, improve the switching frequency and motor efficiency, and broaden the operating range of the system. At the same time, it also has good Dynamic and static performance, reliability, robustness and anti-interference ability.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (2)

1. The permanent magnet synchronous motor torque control method based on the sliding mode flux linkage observer is characterized by comprising the following steps: the method comprises the following steps of carrying out direct torque control on the permanent magnet synchronous motor through an 3/2 coordinate transformation module, a sliding mode flux linkage observer, an electromagnetic torque calculation module, a rotating speed PI regulator, a torque PI regulator, a flux linkage self-adaption module, an expected voltage calculation module, an SVPWM module and an inverter, and specifically comprises the following steps:

step 1), detecting three-phase current i of the permanent magnet synchronous motor_a、i_b、i_cAnd three phase voltage u_a、u_b、u_cObtaining a current component i under a two-phase static alternating current coordinate after 3/2 coordinate transformation_α、i_βAnd a voltage component u_α、u_βThen the current component i_α、i_βAnd a voltage component u_α、u_βSending to a sliding mode flux linkage observer, and adding a current component i_α、i_βSending the data to an electromagnetic torque calculation module;

step 2), according to the current component i_α、i_βAnd a voltage component u_α、u_βThe sliding mode flux linkage observer module estimates the estimated value of the stator flux linkage sizeAnd stator flux linkage phase estimationAnd rotor speed estimateThe method comprises the following specific steps:

step 2.1), according to the current component i_α、i_βAnd a voltage component u_α、u_βConstructing a sliding-mode observer to obtain the back electromotive force e of the motor_α、e_β；

Step 2.2), based on the back electromotive force e_α、e_βObtaining the estimated position of the rotor by a rotor position calculation moduleStep 2.3), estimating the position according to the rotorObtaining a current stator flux linkage vector psi through a stator flux linkage estimation module_α、ψ_β；

Step 2.4), according to the current stator flux linkage vector psi_α、ψ_βBy magnetic flux linkage observationObtaining stator flux linkage size estimation valueAnd rotor speed estimateThe method comprises the following specific steps:

the flux linkage equation of the permanent magnet synchronous motor is derived to obtain:

$\left\{\begin{array}{c}\frac{{\mathrm{d\ψ}}_{\mathrm{\α}}}{dt}=L_s\frac{{\mathrm{di}}_{\mathrm{\α}}}{dt}-{\mathrm{\ω\ψ}}_{\mathrm{\β}}+{\mathrm{\ωL}}_s{i}_{\mathrm{\β}}\\ \frac{{\mathrm{d\ψ}}_{\mathrm{\β}}}{dt}=L_s\frac{{\mathrm{di}}_{\mathrm{\β}}}{dt}+{\mathrm{\ω\ψ}}_{\mathrm{\α}}-{\mathrm{\ωL}}_s{i}_{\mathrm{\α}}\end{array}\right.---\left(11\right)$

wherein L is_sIs a synchronous inductance of the motor; omega is the electrical angular speed of the motor rotor;

from the above equation, a flux linkage observer can be constructed:

$\left\{\begin{array}{c}\frac{d{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}}{dt}=L_s\frac{d{\hat{i}}_{\mathrm{\α}}}{dt}-\widehat{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}+\widehat{\mathrm{\ω}}{L}_s{\hat{i}}_{\mathrm{\α}}-k({\hat{i}}_{\mathrm{\α}}-i_{\mathrm{\α}})-l({\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-{\mathrm{\ψ}}_{\mathrm{\α}})\\ \frac{d{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}}{dt}=L_s\frac{d{\hat{i}}_{\mathrm{\β}}}{dt}+\widehat{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-\widehat{\mathrm{\ω}}{L}_s{\hat{i}}_{\mathrm{\β}}-k({\hat{i}}_{\mathrm{\β}}-i_{\mathrm{\β}})-l({\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}})\\ \frac{d\widehat{\mathrm{\ω}}}{dt}=({\hat{i}}_{\mathrm{\α}}-i_{\mathrm{\α}}){\hat{i}}_{\mathrm{\β}}-({\hat{i}}_{\mathrm{\β}}-i_{\mathrm{\β}}){\hat{i}}_{\mathrm{\α}}+({\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-{\mathrm{\ψ}}_{\mathrm{\α}}){\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-({\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}){\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}\end{array}\right.---\left(12\right)$

wherein l is the gain of the flux linkage observer, and the value of l is greater than zero; k is a sliding mode coefficient;andto estimate α, β axis components of the stator current;

when the system reaches the sliding mode face, we can get:

$\left\{\begin{array}{c}\frac{d{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}}{dt}=L_s\frac{d{\hat{i}}_{\mathrm{\α}}}{dt}-\widehat{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}+\widehat{\mathrm{\ω}}{L}_s{\hat{i}}_{\mathrm{\α}}-l({\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-{\mathrm{\ψ}}_{\mathrm{\α}})\\ \frac{d{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}}{dt}=L_s\frac{d{\hat{i}}_{\mathrm{\β}}}{dt}+\widehat{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-\widehat{\mathrm{\ω}}{L}_s{\hat{i}}_{\mathrm{\β}}-l({\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}})\\ \frac{d\widehat{\mathrm{\ω}}}{dt}=({\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}-{\mathrm{\ψ}}_{\mathrm{\α}}){\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-({\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}){\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}\end{array}\right.---\left(13\right)$

and (3) subtracting the formula (13) from the formula (11) to obtain an error equation of the flux linkage observer:

$\left\{\begin{array}{c}\frac{d{\widetilde{\mathrm{\ψ}}}_{\mathrm{\α}}}{dt}=-\widetilde{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}+\widehat{\mathrm{\ω}}{\widetilde{\mathrm{\ψ}}}_{\mathrm{\β}}-l{\widetilde{\mathrm{\ψ}}}_{\mathrm{\α}}\\ \frac{d{\widetilde{\mathrm{\ψ}}}_{\mathrm{\β}}}{dt}=-\widetilde{\mathrm{\ω}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}+\widehat{\mathrm{\ω}}{\widetilde{\mathrm{\ψ}}}_{\mathrm{\α}}-l{\widetilde{\mathrm{\ψ}}}_{\mathrm{\β}}\\ \frac{d\widehat{\mathrm{\ω}}}{dt}={\widetilde{\mathrm{\ψ}}}_{\mathrm{\α}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\β}}-{\widetilde{\mathrm{\ψ}}}_{\mathrm{\β}}{\widehat{\mathrm{\ψ}}}_{\mathrm{\α}}\end{array}\right.---\left(14\right)$

wherein, omega is the electrical angular velocity of the motor rotor; l is the gain of the flux linkage observer, and the value of the gain is greater than zero;

the stator flux linkage size estimation value can be calculated according to the formula (14)And rotor speed estimate

Step 2.5), estimating the size of the stator flux linkage according to the estimated value of the size of the stator flux linkageObtaining stator flux linkage phase estimation value through flux linkage position calculation module

Step 3), setting the rotating speed omega^*And said rotor speed estimateAfter difference is made, a given torque Te is obtained through a rotating speed PI regulator^*；

Step 4), estimating the size of the stator flux linkage according to the estimated valueAnd the current component i_α、i_βThe electromagnetic torque calculation module obtains the actual torque Te of the motor;

step 5), the given torque Te^*Obtaining stator flux set value psi through flux linkage self-adaptive module_sref；

Step 6) of applying the predetermined torque Te^*Obtaining an output △ through a torque PI regulator after making a difference with the actual torque Te of the motor;

step 7), the output quantity △ and the stator flux linkage given value psi_srefStator flux linkage size estimationAnd stator flux linkage phase estimationObtaining a two-phase alternating current voltage reference value on a two-phase static coordinate system through an expected voltage calculation module

Step 8) according to the stator flux linkage vector position and the two-phase alternating voltage reference valueAnd after a corresponding space voltage vector is selected from the switch state table, a modulation signal is output to the inverter through the SVPWM module, and the direct torque control of the permanent magnet synchronous motor is realized through the inverter.

2. The permanent magnet synchronous motor torque control method based on the sliding mode flux linkage observer according to claim 1, characterized in that: the variable structure function of the sliding mode observer in the step 2.1) is a sigmoid function.