阅读说明：本技术 一种新型双滑模观测器spmsm无传感器复合控制方法 (Novel SPMSM sensorless compound control method of double-sliding-mode observer ) 是由 彭思齐 蒋雨函 于 2020-11-12 设计创作，主要内容包括：本发明提供了一种新型双滑模观测器的永磁同步电机无传感器复合控制方法,本发明设计了两种滑模观测器,其一提供了一种新型指数型分段滑模函数对反电动势进行观测。其二设计了一种滑模观测器观测负载转矩对分段PI控制器进行参数微调,同时将估计负载转矩引入q轴进行前馈补偿。在q轴电流内环设计了二阶滑模控制器,提高了q轴电流的跟踪性能,间接控制电磁转矩。本发明所提供的新型指数型分段滑模函数,更有利于反电动势观测,削弱了系统抖振现象；负载滑模观测器观测负载转矩对分段PI控制器进行参数微调同时进行前馈补偿,提高系统带负载能力；二阶滑模控制器减小了转矩脉动。本发明在永磁同步电机的中高速域无传感器控制中具有优良的动稳态性能和广泛的应用价值。(The invention provides a novel sensorless compound control method for a permanent magnet synchronous motor of a double-sliding-mode observer, and designs two sliding-mode observers, wherein one of the sliding-mode observers provides a novel exponential segmented sliding-mode function to observe back electromotive force. And secondly, a sliding mode observer is designed to observe the load torque to carry out parameter fine adjustment on the segmented PI controller, and meanwhile, the estimated load torque is introduced into a q axis to carry out feedforward compensation. A second-order sliding mode controller is designed in the q-axis current inner ring, so that the tracking performance of the q-axis current is improved, and the electromagnetic torque is indirectly controlled. The novel exponential type segmented sliding mode function provided by the invention is more favorable for counter electromotive force observation, and the buffeting phenomenon of the system is weakened; the load sliding mode observer observes the load torque to carry out parameter fine adjustment on the segmented PI controller and feed-forward compensation at the same time, so that the load carrying capacity of the system is improved; the second order sliding mode controller reduces torque ripple. The invention has excellent dynamic and steady state performance and wide application value in the medium and high speed domain sensorless control of the permanent magnet synchronous motor.)

1. A novel double-sliding-mode observer compound control method realizes sensorless control of a permanent magnet synchronous motor in a medium-high speed domain, and is characterized by comprising the following steps:

(1) sampling three-phase current i_abcVoltage u_abcObtaining the current i under a static coordinate system through Clark coordinate transformation_αβVoltage u_αβIntegrating the current state equation of the reconstructed permanent magnet synchronous motor to obtain the current value of the estimated static coordinate systemWill estimate the current value of the stationary coordinate systemAnd the current value i of the actual static coordinate system_αβPerforming a difference operation to obtain a current error valueError value of currentIs set as a slip form surface s_αβFinally according to a novel exponential sectional sliding mode function z(s)_αβ) The back electromotive force was observed.

(2) A load sliding-mode observer is designed to observe load torque at mechanical angular velocityAnd the fed-back q-axis current as input, and outputting the estimated load torqueTo be provided withThe magnitude of the load torque is used as a judgment condition to switch parameters of the rotating speed outer ring segmented PI controller, and the estimated load torque is simultaneously usedAdding to the q-axis estimated currentTo perform feed forward compensation.

(3) By q-axis current error valueAnd as a sliding mode surface, a second-order sliding mode controller is designed to indirectly control the electromagnetic torque.

2. The novel composite control method of the double sliding-mode observer for the permanent magnet synchronous motor according to claim 1 is characterized in that a novel exponential segmented sliding-mode function is provided, the characteristic of the novel exponential segmented sliding-mode function is more favorable for observation of back electromotive force, and buffeting is weakened, wherein the novel exponential segmented sliding-mode function is expressed as:

where σ is the boundary layer thickness, s_αβIs a slip form surface.

3. The novel composite control method of the double-sliding-mode observer for the permanent magnet synchronous motor is characterized in that the load sliding-mode observer is designed to observe load torque to carry out parameter fine adjustment on a segmented PI controller, and meanwhile, the estimated load torque is added into a q axis to carry out feedforward compensation.

4. The novel composite control method of the double-sliding-mode observer realizes sensorless control of the permanent magnet synchronous motor in a medium-high speed domain according to claim 1, and is characterized in that a quadrature axis current inner loop uses a second-order sliding-mode controller of a super-twisting algorithm. Designing q-axis current error as sliding mode surface

Designing a q-axis current controller:

。

Technical Field

The invention belongs to the field of control of permanent magnet synchronous motors, relates to a novel sensorless compound control method of a double-sliding-mode observer, and particularly relates to a system model for realizing sensorless control in a high-speed domain of a permanent magnet synchronous motor by the novel double-sliding-mode observer compound control method which is simple, easy to implement and good in effect.

Background

Surface-mounted Permanent Magnet Synchronous motors (SPMSM) are mainly classified into surface-mounted Permanent Magnet Synchronous motors (SPMSM) and Interior Permanent Magnet Synchronous Motors (IPMSM). The speed-regulating device has the characteristics of simple structure, small volume, high power density, high efficiency and easiness in maintenance, and the excellent speed-regulating performance of the speed-regulating device enables the speed-regulating device to be widely applied to various fields, such as industrial manufacturing, intelligent robots, new energy automobiles and the like. With the wider application of the permanent magnet synchronous motor, the requirement on the control performance of the permanent magnet synchronous motor is higher and higher. At present, a plurality of scholars mainly concentrate on two aspects of structural design and control performance of a motor, a good control algorithm can greatly improve the performance of a system, and the control methods commonly used for the permanent magnet synchronous motor mainly comprise vector control (FOC) and Direct Torque Control (DTC). The vector control common PI controller realizes double closed loop control, decomposes a current vector into an exciting current and a torque current by measuring a stator current vector of the permanent magnet synchronous motor and then performing coordinate transformation, indirectly controls the flux linkage and the torque of the permanent magnet synchronous motor, and has the characteristics of high precision and good dynamic and stable performance. The direct torque control is usually based on bang-bang control, the flux linkage and the torque of the permanent magnet synchronous motor are directly controlled, coordinate transformation and current control in vector control are omitted, and the method has better rapidity.

In order to realize the high-performance double-closed-loop vector control of the permanent magnet synchronous motor, the aim of obtaining real-time and accurate rotating speed information and rotor position information is to install mechanical sensors such as photoelectric encoders mostly. However, the mechanical sensor has the problems of high cost, high possibility of damage, high dependence of the system on the mechanical sensor, poor severe performance of the working environment and the like. Therefore, in order to solve various problems brought by mechanical sensors, the position and the speed of a rotor are estimated through an algorithm to replace the mechanical sensors to realize a permanent magnet synchronous motor double closed-loop vector control strategy. Therefore, the research on the sensorless control algorithm of the permanent magnet synchronous motor becomes a modern hot trend.

To realize sensorless permanent magnet synchronous motors, two methods are usually used: one is based on signal injection, and the principle is to estimate the rotor position by using the saliency of the motor, and the following are commonly used: a pulsating voltage injection method, a rotating high-frequency voltage injection method; the other method is to use an observer to observe the back electromotive force in the dynamic model to extract the rotor position information. According to the mathematical model of the permanent magnet synchronous motor, the back electromotive force is known to be related to the electrical angular velocity, so that the back electromotive force is obvious only at medium and high speeds, which is beneficial to observation and extraction. Compared with the other two methods, the sliding-mode observer method has more remarkable advantages and more mature development in a sensorless control system. However, the traditional sliding mode observer has the problems of serious buffeting phenomenon and poor loading capacity, so that the control performance of the whole system is poor. Therefore, the sliding mode observer control algorithm which is more excellent in dynamic and steady state performance, less in buffeting phenomenon and higher in loading capacity has wider practical application value.

Disclosure of Invention

The invention aims to solve the problems that a rotating speed loop and a current loop PI controller have poor tracking performance and difficult parameter adjustment in the double-closed-loop vector control process of a permanent magnet synchronous motor and a traditional sliding-mode observer has buffeting and poor loading capacity.

The invention provides a novel exponential type sectional sliding mode function to replace a switch function in a traditional sliding mode observer, a rotating speed outer ring provides a sectional PI controller, a sliding mode load observer is designed to observe load torque to carry out parameter fine adjustment on the sectional PI controller, the observed load torque is introduced into a q axis to carry out feedforward compensation, and a q axis current inner ring provides a second-order sliding mode controller of a super-twisting algorithm.

The technical scheme adopted for solving the technical problems is as follows:

the invention provides a novel sensorless compound control method of a double sliding mode observer, aiming at weakening buffeting phenomenon and improving dynamic steady state performance and loaded capacity of a system, comprising the following steps:

the novel exponential type subsection sliding mode function is provided for observing back electromotive force, and the expression of the novel exponential type subsection sliding mode function is as follows:

where σ is the boundary layer thickness, s_αβIs a slip form surface.

The function has the saturation characteristic of an opening and closing function outside a boundary layer, has the small-part step characteristic at the boundary layer, can accelerate the speed of the system approaching the sliding mode surface on the premise of ensuring that the function does not penetrate through the sliding mode surface, has the characteristics of index approaching law and continuity inside the boundary layer, is slower in approaching when approaching the sliding mode surface, is not easy to penetrate through the sliding mode surface, and avoids the phenomenon of multiple fluctuation up and down along the sliding mode surface in the convergence process of the system, so that the buffeting phenomenon can be well weakened. Stability analysis is carried out on the Lyapunov by adopting a Lyapunov stability criterion:

the slip form surface is arranged asReconstructing a current state equation of the permanent magnet synchronous motor:

subtracting the reconstructed current state equation from the mathematical model of the permanent magnet synchronous motor to obtain a current error state equation:

wherein K is a sliding mode gain; r_s，L_sRespectively a stator resistor and an inductor; i.e. i_α,i_β，u_α,u_βStator current and voltage under a static coordinate system respectively; e.g. of the type_α,e_βComponents of back electromotive force on the alpha, beta axes, w_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage, theta_eIn electrical degrees.

When in useWhen the current is estimated to be equal to the actual current, the back electromotive force can be observed by using a novel exponential sectional sliding mode function, namely:

the stability analysis is carried out on the novel exponential type segmented sliding mode observer according to the Lyapunov stability criterion, and a Lyapunov function is selectedIf the condition is satisfiedThe system is gradually stabilized on the sliding mode surface, and the sliding mode exists, so the method comprises the following steps:

whereinBeing a negative definite matrix, an inductive matrixCounter electromotive force matrix

Because of the fact thatIf it is to satisfyOnly need to satisfyThe calculation only needs to satisfy the sliding mode gain K > max (| e)_α,e_βI) to obtain the final product. A novel exponential type segmented sliding mode observer designed for selecting accurate sliding mode gain K through a trial and error method meets the Lyapunov stability criterion, and has asymptotic stability.

Considering that the temperature of the motor is increased in the process of operating with a load and the inductance parameter is reduced along with the temperature, the parameter setting of the rotating speed outer ring PI controller is changed, and the system can better adapt to no-load operation and on-load operation. In consideration of the immeasurability of the load in the practical application process, the invention designs the sliding-mode observer to observe the load torque in real time, so as to realize the sectional PI parameter fine tuning and feedforward compensation. The design and Lyapunov stability analysis of the load sliding-mode observer is as follows:

reconstructing according to a torque dynamic state equation of the permanent magnet synchronous motor, observing load torque by using a sliding mode observer, and designing a sliding mode observer equation:

wherein the sliding mode control law is U ═ a₁sign(s_w)-a₂s_w；a₁，a₂Are control parameters.

Subtracting the permanent magnet synchronous motor torque dynamic state equation from the sliding-mode observer equation to obtain a torque dynamic error state equation:

wherein the slip form surface is set to mechanical angular velocity errorLoad torque error To estimate mechanical angular velocity; j is moment of inertia; t is_eIs an electromagnetic torque;to estimate the load torque; l is a control parameter. Selecting a Lyapunov function according to a Lyapunov stability criterionThe system needs to satisfy the stability conditionThe following can be obtained:

wherein the control parameter a₁，a₂The tuning process is analyzed as follows:

(1) when the mechanical angular velocity error e₁When is more than 0, only the requirement is satisfiedCan meet the criterion of Lyapunov stability.

When e₂When is more than 0, only the requirement is satisfieda₂≥0。

When e₂When less than 0, only the requirement is satisfieda₂≥0。

(2) When the mechanical angular velocity error e₁When less than 0, only the requirement is satisfiedCan meet the criterion of Lyapunov stability.

When e₂When is more than 0, only the requirement is satisfieda₂≥0。

When e₂When less than 0, only the requirement is satisfieda₂≥0。

Therefore, the designed load sliding-mode observer can reach and be stabilized on the sliding-mode surface according to the equivalent control principle, namelyWhile controlling the parameter a₁，a₂In a control range ofa₂Not less than 0, fine tuning is carried out according to a trial-and-error method, and the correct a is selected₁， a₂. Stabilized behind the slip form faceObtained after solvingWherein c is a constant, when l is less than 0, the load torque error converges to 0 at an exponential approach speed, i.e. the observed load torque can track the actual load torque in real time.

In summary, the estimated mechanical angular velocityAnd q-axis feedback current i_qInputting the control parameters into a designed load sliding mode observer, setting the range l of the control parameters to be less than 0,a₂and (4) the load torque is not less than 0, and correct control parameters are debugged according to a trial-and-error method, so that the real-time observation of the load torque is realized.

The problem that torque pulsation is large in the process of controlling the double closed-loop vector of the permanent magnet synchronous motor due to poor tracking performance of a PI controller is considered. Calculating formula T according to electromagnetic torque_e＝1.5p_nψ_fi_qQ-axis current i_qAnd electromagnetic torque T_eA linear relationship is presented. According to the invention, a second-order sliding mode controller is designed on the q axis to improve the tracking performance of q axis current and indirectly reduce torque ripple. The invention sets the quadrature axis current sliding mode surface asAccording to a specific expression of a second-order sliding mode controller of a super-twisting algorithm, a q-axis current controller can be designed as follows:wherein K_p，K_iSign () is a switching function for design parameters.

The invention provides a novel SPMSM sensorless compound control method of a double sliding-mode observer, which carries out Matlab/simulink simulation verification by using a permanent magnet synchronous motor model, wherein the parameter of the permanent magnet synchronous motor is stator resistance R_s2.875 Ω, stator inductance L_s0.0085H, permanent magnet linkage psi_f0.175, 4 pole pair number p, 0.001N · M moment of inertia J, and a 5N · M load at 0.2 s.

The invention has the following technical characteristics:

1. the thickness sigma of the boundary layer of the novel exponential type segmented slip-form function is 0.002, and the slip-form gain coefficient K is 200.

2. The parameter setting a of the load sliding mode observer₁＝10000，a₂＝500。

3. Setting parameters of a second-order sliding mode controller of the super-twisting algorithm: k_p＝180，K_i＝20。

The novel sensorless compound control system model of the double sliding-mode observer has the beneficial effects that:

1. the novel exponential type segmented sliding mode function is provided, the buffeting phenomenon is weakened, the observation of counter electromotive force is facilitated, and the system stability is improved.

2. A segmented PI controller is provided at the outer ring of the rotating speed, a sliding mode observer is designed to observe load torque to carry out parameter fine adjustment on the segmented PI controller, so that the segmented PI controller is suitable for two different working conditions of no-load operation and sudden load, meanwhile, the load torque is introduced into a q axis to carry out feedforward compensation, and the load carrying capacity of a system is improved.

3. The q-axis current inner loop provides second-order sliding mode control of a super-twisting algorithm, so that the q-axis current tracking performance is improved, and torque ripple is reduced.

Drawings

The invention is further illustrated with reference to the following figures and examples.

Fig. 1 and fig. 1 are schematic block diagrams of a PMSM composite control method of a novel double sliding-mode observer provided by the invention.

Fig. 2 is a diagram of a novel exponential segmented sliding mode function according to the present invention.

Fig. 3 and fig. 3 are schematic block diagrams of the novel exponential segmented sliding-mode observer provided by the invention.

Fig. 4 and fig. 4 are flow charts of the segmented PI controller according to the present invention.

Fig. 5 and fig. 5(a) are rotation speed diagrams of the novel dual sliding mode observer SPMSM sensorless compound control method provided by the invention.

Fig. 5(b) is a rotation speed diagram of the conventional sliding-mode observer SPMSM sensorless control method.

FIG. 6 and FIG. 6(a) are the rotation speed error diagrams of the novel dual sliding mode observer SPMSM sensorless compound control method according to the present invention.

FIG. 6(b) is a diagram of the rotational speed error of the conventional sliding-mode observer SPMSM sensorless control method.

Fig. 7(a) is an electromagnetic torque diagram of the new double sliding mode observer SPMSM sensorless compound control method according to the present invention.

Fig. 7(b) is an electromagnetic torque diagram of a conventional sliding-mode observer SPMSM sensorless control method.

Fig. 8 and fig. 8 are rotor position diagrams of the new double sliding mode observer SPMSM sensorless compound control method according to the present invention.

FIG. 9 is a graph of estimated load torque of a load sliding mode observer according to the present invention

Fig. 10 is a load torque error diagram between the estimated load torque and the actual load torque of the load sliding mode observer proposed by the present invention.

Detailed Description

Sampling three-phase current i_abcVoltage u_abcObtaining the current i under a static coordinate system through Clark transformation_αβVoltage u_αβAnd obtaining an estimated current value after performing integral operation on the reconstructed current state equationThen sample the current i with the actual_αβSubtracting to obtain the current error value The input of the novel exponential type subsection sliding mode function provided by the invention is processed by a sliding mode gain K, and the high order harmonic is filtered by a low pass filter to obtain the estimated back electromotive force At this time Andinputting the electrical angle into a divider to perform division operation to obtain an estimated electrical angleThe estimated electrical angle value is obtained through the calculation of an arc tangent functionWill be provided withAndfirst square sum and then square root to obtainDivision by the permanent magnet flux linkage psi by a divider_fObtaining an estimated electrical angular velocityBy estimated electrical angle valuesAnd estimated electrical angular velocityAnd realizing a double closed-loop vector control strategy of the permanent magnet synchronous motor.

In the process of motor load operation, the temperature of the motor can rise, the inductance parameter of the motor can change greatly, and a single PI controller is difficult to adapt to two working conditions of no load and load. The invention will estimate the electrical angular velocityConversion into estimated mechanical angular velocityPost-sum feedback q-axis current i_qThe load torque is input into a load sliding mode observer designed by the invention together to obtain an estimated load torqueWill estimate the load torqueAnd (3) fine tuning the rotating speed outer ring segmented PI parameters as a judgment condition, wherein the specific implementation process is as follows:

(1) when estimated load torqueAnd when the error tolerance epsilon is smaller than the set error tolerance epsilon, adopting a rotating speed outer ring PI parameter of no-load operation.

(2) When estimated load torqueAnd when the error tolerance is larger than the set error tolerance epsilon, adopting a rotating speed outer ring PI parameter which runs with load. While simultaneously estimating the load torqueAnd performing feed-forward compensation on the input q-axis. When the system is loaded suddenly, the rotating speed is suddenly reduced, and the response is fast. The load resistance of the system is improved.

Estimated q-axis current obtained by rotating speed outer ring segmented PI controllerQ-axis actual current i under synchronous rotating coordinate system with feedback_qSubtracting to obtain a current error valueError value of currentInput into the second order sliding mode controller to obtain the estimated q-axis voltage

In summary, the embodiment of the invention provides a novel composite control method of a double-sliding-mode observer, which realizes sensorless control of a permanent magnet synchronous motor in a medium-high speed domain. The novel exponential type segmented slip form function is designed, the saturation characteristic of the switch function is achieved outside the boundary layer, the boundary layer has a small step characteristic, continuity and index approaching law are achieved in the boundary layer, fluctuation of the slip form surface is avoided for multiple times, and observed counter electromotive force is more accurate. Will estimate the back electromotive force Estimating the rotor position by an arc tangent function to obtain an estimated rotor position angleAnd estimating electrical angular velocityThe buffeting phenomenon is weakened, and the precision is improved. Then estimating the electrical angular velocityThe load sliding mode observer is used as the input of the load sliding mode observer, the estimated load torque is output to carry out parameter fine adjustment on the segmented PI controller, and meanwhile, the estimated load torque is introduced into q-axis current estimated by q-axis to carry out feed-forward compensation, so that the system can adapt to two working conditions of no-load operation and sudden load, and the load resisting capacity of the system is improved. The current inner ring is designed with a second-order sliding mode controller to improve the tracking performance of the q-axis current and indirectly controlElectromagnetic torque is generated, and torque pulsation is reduced.

The application effect of the invention is described in detail by combining a Matlab/simulink simulation diagram as follows:

compared with fig. 5(a) and fig. 5(b), the rotation speed diagram of the sliding mode observer is smoother, the buffeting phenomenon can be well weakened, when 5N · M load is suddenly added at 0.2s, the rotation speed sudden drop is smaller, the rotation speed recovery is faster, and the sliding mode observer has better load carrying capacity; comparing fig. 6(a) and fig. 6(b) to fig. 6(a), the error of the present invention is smaller than that of the conventional sliding-mode observer, and the error of the present invention is nearly 0; comparing fig. 7(a) and fig. 7(b), the electromagnetic torque ripple of the present invention is smaller compared to the conventional sliding mode observer; fig. 9 shows that the load sliding mode observer designed by the invention can observe the actual load torque in real time, and has accurate observation effect and fast response; analysis of fig. 10 the error between the estimated load torque and the actual load torque of fig. 10 is close to 0. The simulation graphs show that the novel SPMSM sensorless compound control method of the double sliding mode observer can weaken buffeting, and has better dynamic and steady performance and load carrying capacity, so that the correctness and the effectiveness of the method are proved.