Observer-based permanent magnet synchronous motor cascade control system and parameter setting method

Abstract

The invention provides a permanent magnet synchronous motor cascade control system based on an observer and a parameter setting method, and belongs to the technical field of permanent magnet synchronous motor control. Firstly, a basic dynamic equation of the surface-mounted permanent magnet synchronous motor on a two-phase synchronous rotation orthogonal coordinate system is deduced; then, a novel disturbance observer is constructed for estimating the concentrated disturbance of the system. And finally, establishing an augmentation system containing observer dynamics, and designing cascade controller parameters according to a nominal system of the augmentation system. According to the method, the parameter uncertainty and unknown disturbance of the permanent magnet synchronous motor can be accurately estimated, the feed-forward compensation value of the permanent magnet synchronous motor is compounded into the design of the feedback controller, and the gain parameter setting method is simple, easy to implement and suitable for the design of a high-performance servo control system of the permanent magnet synchronous motor.

Description

Technical Field

[0001] The present application relates to the technical field of permanent magnet synchronous motor control, and in particular to an observer-based permanent magnet synchronous motor cascade control system and a parameter setting method. Background Art

[0002] In recent years, with the rapid development of power electronics, automatic control and computer technologies, AC servo control systems have gradually replaced DC drive control systems in the field of high-performance speed regulation. Permanent magnet synchronous motors have a dominant position in AC speed regulation systems due to their high power density and fast dynamic response speed. However, during the operation of permanent magnet synchronous motors, electrical and mechanical parameters will inevitably change, and the influence of external load disturbances will cause controller parameters to mismatch, thereby deteriorating the performance of the control system. In order to make the designed permanent magnet synchronous motor servo system have good dynamic performance, the composite control strategy based on the observer has become a research hotspot in the field of motor control. However, the traditional cascade control strategy based on the observer has a relatively complex gain parameter setting and a large number of gain parameters. The observer constructed by the existing method does not consider the unmodeled dynamics, and usually depends on the actual parameters of the controlled object, which inevitably differs from the nominal parameters. In addition, there is a lack of theoretical analysis of the augmented system containing the observer dynamics, which makes it difficult to take into account the rapid convergence and accurate estimation of the observer, and it is impossible to achieve effective feedforward compensation and high-precision control of the system. It can be seen that the design of the disturbance observer and the setting of the controller parameters play a vital role in improving the dynamic performance of the control system.

[0003] The disturbance observer (DO) estimates the concentrated disturbance to the system online based on the input and output dynamics of the controlled object. By adopting a composite control strategy, that is, feed-forwarding the real-time estimated value of the disturbance into the design of the feedback controller, the research of high-performance servo control algorithms can be achieved. Among many feedback controllers, proportional integral (PI) control is widely used because of its simple structure and easy parameter tuning and implementation. Therefore, it is very important to design a permanent magnet synchronous motor cascade control system based on an observer and a parameter tuning method. Summary of the invention

[0004] The present application provides an observer-based permanent magnet synchronous motor cascade control system and a parameter tuning method, which can be used to solve the technical problem that the gain parameter tuning of the traditional observer-based cascade control strategy is relatively complex.

[0005] The present application provides a permanent magnet synchronous motor cascade control system based on an observer, the system includes a speed tracking error module, a speed loop PI controller PI_m module, a speed loop disturbance observer DO_m module, a q-axis current tracking error module, a q-axis current loop PI controller PI_q module, a q-axis current loop disturbance observer DO_q module, a d-axis current tracking error module, a d-axis current loop PI controller PI_d module, a d-axis current loop disturbance observer DO_d module, a q-axis current dynamic module, a d-axis current dynamic module, and a speed dynamic module;

[0006] The speed tracking error module is based on the given speed command and the feedback speed signal ω m , calculate the difference to get the speed tracking error e m , and sent to the speed loop PI controller PI_m module;

[0007] The speed loop PI controller PI_m module performs proportional integral operation on the input signal to obtain the corresponding speed loop control signal u m , and sent to the speed loop disturbance observer DO_m module and the q-axis current tracking error module at the same time;

[0008] The speed loop disturbance observer DO_m module is based on the speed loop control signal u m and the feedback speed signal ω m , get the disturbance estimate of the velocity loop And sent to the q-axis current tracking error module;

[0009] The q-axis current tracking error module is based on the given q-axis current command And the feedback q-axis current signal i q , calculate the difference to get the q-axis current tracking error e q , and sent to the q-axis current loop PI controller PI_q module;

[0010] The q-axis current loop PI controller PI_q module performs proportional integral operation on the input signal to obtain the corresponding q-axis current loop control signal u qo , and sent to the q-axis current loop disturbance observer DO_q module and the q-axis current dynamic module at the same time;

[0011] The q-axis current loop disturbance observer DO_q module is based on the q-axis current loop control signal u qo And the feedback q-axis current signal i q , get the disturbance estimate of the q-axis current loop And sent to the q-axis current dynamic module;

[0012] The d-axis current tracking error module is based on the given d-axis current command and the feedback d-axis current signal id , calculate the difference to get the d-axis current tracking error e d , and sent to the d-axis current loop PI controller PI_d module;

[0013] The d-axis current loop PI controller PI_d module performs proportional integral operation on the input signal to obtain the corresponding d-axis current loop control signal u do , and sent to the d-axis current loop disturbance observer DO_d module and the d-axis current dynamic module at the same time;

[0014] The d-axis current loop disturbance observer DO_d module is based on the d-axis current loop control signal u do and the feedback d-axis current signal i d , get the disturbance estimate of the d-axis current loop And sent to the d-axis current dynamic module;

[0015] The q-axis current dynamic module is based on the input q-axis signal and q-axis current loop disturbance f q , the response is the q-axis current signal i q , and sent to the q-axis current tracking error module, the q-axis current loop disturbance observer DO_q module and the speed dynamic module at the same time;

[0016] The d-axis current dynamic module is based on the input d-axis signal and the d-axis current loop disturbance f d , the response is the d-axis current signal i d , and sent to the d-axis current tracking error module and the d-axis current loop disturbance observer DO_q module at the same time;

[0017] The q-axis current signal i input by the speed dynamic module q and the velocity loop disturbance f d , the response is the speed signal ω m , and sent to the speed tracking error module and the speed loop disturbance observer DO_m module at the same time.

[0018] The present application provides a permanent magnet synchronous motor cascade control system based on an observer and a parameter setting method, the method is performed by a permanent magnet synchronous motor cascade control system based on an observer provided by the present application, and the method includes:

[0019] Step 1: Establish the basic dynamic equation of the permanent magnet synchronous motor in a two-phase synchronous rotating orthogonal coordinate system;

[0020] Step 2: construct a new disturbance observer;

[0021] Step 3: Determine the cascade control law based on the nominal system.

[0022] Furthermore, the basic dynamic equation of the permanent magnet synchronous motor in the two-phase synchronous rotating orthogonal coordinate system in step 1 is:

[0023]

[0024] Among them, d / dt is the differential operator; i d and i q are the currents of the d-axis and q-axis stator windings respectively; R s and L s are the resistance and inductance of the stator winding respectively; u d and u q are the voltages of the d-axis and q-axis stator windings respectively; f d =-ω e L s i q and f q =ω e (L s i d +ψ f ) are the current loop disturbances of the d-axis and q-axis respectively; ψ f is the permanent magnet flux; F is the viscous friction coefficient; J is the moment of inertia; K T =3p n ψ f / 2 is the electromagnetic torque coefficient; p n is the number of magnetic pole pairs; f m =(T m +K T e q ) / K T is the velocity loop disturbance; T m is the load torque disturbance; is the q-axis current tracking error, is the given q-axis current command; ω e and ω m are the electrical angular velocity and the mechanical angular velocity respectively, and satisfy ω e =p n ω m .

[0025] Furthermore, in step 1, to decouple ω e For current i d and i q The back EMF is modeled as a disturbance of the current loop; the q-axis current tracking error e q Introduced into the mechanical dynamic equation, it forms a load torque disturbance T m The modeled current loop and speed loop disturbances have the same gain as the control input.

[0026] Furthermore, the new disturbance observer constructed in step 2 is as follows:

[0027]

[0028] Among them, DO_d and DO_q are the disturbance observers of the d-axis and q-axis current loops respectively; DO_m is the disturbance observer of the speed loop; ξ d and q are the observer variables of the d-axis and q-axis current loops respectively; m is the observer variable of the speed loop; l c and l s are the observer gains of the current loop and the speed loop respectively;

[0029] Considering that actual industrial controlled objects inevitably have parameter uncertainties, such as unmodeled dynamics and parameter changes, etc. Therefore, the present invention designs a novel disturbance observer based on nominal parameters (indicated by an additional subscript "n") and information of the dynamic system.

[0030] Furthermore, the new disturbance observer constructed in step 2 has the following transfer function:

[0031]

[0032] Wherein, “(s)” represents the Laplace transform of the corresponding variable, and “s” is the Laplace transform operator;

[0033] The disturbance observer is essentially a first-order low-pass filter, which can realize accurate real-time estimation and compensation of unknown disturbances, and the convergence speed is proportional to the observer gain.

[0034] Furthermore, in step 2, the dynamic system equations and the constructed new disturbance observer are combined to obtain the following augmented system:

[0035]

[0036] Among them, ε c =1 / l c and ε s =1 / l s are the singular perturbation parameters of the current loop and velocity loop augmented systems respectively;

[0037] According to the famous singular perturbation theory, when the observer gain is large enough, the augmented system is equivalent to the quasi-steady-state equation shown below:

[0038]

[0039] The novel disturbance observer makes the augmented system including the observer dynamics behave as a nominal system, and the control performance is not affected by unknown disturbances and motor parameter uncertainties.

[0040] Furthermore, the PI controller designed in step 3 is as follows:

[0041]

[0042] Among them, u do and u qo are the d-axis and q-axis current loop control signals respectively; u m is the speed loop control signal; e d and e q are the d-axis and q-axis current tracking errors respectively; e m is the speed tracking error; K Pc =ω c L sn and K Ic =ω c R sn are the proportional and integral gains of the current loop, ω c is the bandwidth of the current loop; K Ps =ω s J n / K Tn and K Is =ω s F n / K Tn are the proportional and integral gains of the speed loop, ω s is the bandwidth of the speed loop.

[0043] Furthermore, for the observer gain in step 2 and the controller parameters in step 3, the parameter tuning method is as follows:

[0044]

[0045] Among them, T s is the interrupt execution cycle; T cn =L sn / R sn is the nominal electrical time constant of the current loop.

[0046] From the above constraints, it can be seen that the present invention only needs to give the bandwidth ω of the current loop c , it is possible to adjust all parameters of the disturbance observer and cascade controller, reducing the difficulty and number of parameter adjustment, and has the advantages of easy design and implementation. In addition, since the observer gains of the current loop and the speed loop are both greater than their corresponding bandwidths, the rapid convergence of the observer is guaranteed, and high-precision estimation and effective feedforward compensation can be performed for unknown disturbances and uncertainties in motor parameters.

[0047] 1. Based on the two-phase synchronous rotating orthogonal coordinate system, the cross-coupled back-EMF and q-axis current tracking error are introduced into the modeling of current loop and speed loop disturbances respectively, and a more accurate electrical and mechanical dynamic model is obtained.

[0048] 2. The constructed disturbance observer has low-pass filtering characteristics, which can realize the estimation of permanent magnet synchronous motor parameter uncertainty and external load disturbance.

[0049] 3. A new disturbance observer is designed based on the nominal parameters and information of the dynamic system, which realizes the tuning of the bandwidth-based cascade controller parameters, reduces the difficulty and number of parameter adjustments, and has the advantages of easy design and implementation, which is suitable for the design of high-performance servo control systems for permanent magnet synchronous motors.

[0050] 4. According to the famous singular perturbation theory, the introduction of the novel disturbance observer constructed by the present invention makes the augmented system including the observer dynamics behave as a nominal system, and its control performance is not affected by unknown disturbances and motor parameter uncertainties. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a block diagram of a permanent magnet synchronous motor cascade control system based on a disturbance observer. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0053] A cascade control system of permanent magnet synchronous motor based on observer, such as Figure 1 As shown, it includes a speed tracking error module, a speed loop PI controller PI_m module, a speed loop disturbance observer DO_m module, a q-axis current tracking error module, a q-axis current loop PI controller PI_q module, a q-axis current loop disturbance observer DO_q module, a d-axis current tracking error module, a d-axis current loop PI controller PI_d module, a d-axis current loop disturbance observer DO_d module, a q-axis current dynamic module, a d-axis current dynamic module, and a speed dynamic module, wherein:

[0054] The speed tracking error module is based on the given speed command and the feedback speed signal ω m , calculate the difference to get the speed tracking error e m , and sent to the speed loop PI controller PI_m module;

[0055] The speed loop PI controller PI_m module performs proportional integral operation on the input signal to obtain the corresponding speed loop control signal u m, and sent to the speed loop disturbance observer DO_m module and the q-axis current tracking error module at the same time;

[0056] The speed loop disturbance observer DO_m module is based on the speed loop control signal u m and the feedback speed signal ω m , get the disturbance estimate of the velocity loop And sent to the q-axis current tracking error module;

[0057] The q-axis current tracking error module is based on the given q-axis current command And the feedback q-axis current signal i q , calculate the difference to get the q-axis current tracking error e q , and sent to the q-axis current loop PI controller PI_q module;

[0058] The q-axis current loop PI controller PI_q module performs proportional integral operation on the input signal to obtain the corresponding q-axis current loop control signal u qo , and sent to the q-axis current loop disturbance observer DO_q module and the q-axis current dynamic module at the same time;

[0059] The q-axis current loop disturbance observer DO_q module is based on the q-axis current loop control signal u qo And the feedback q-axis current signal i q , get the disturbance estimate of the q-axis current loop And sent to the q-axis current dynamic module;

[0060] The d-axis current tracking error module is based on the given d-axis current command and the feedback d-axis current signal i d , calculate the difference to get the d-axis current tracking error e d , and sent to the d-axis current loop PI controller PI_d module;

[0061] The d-axis current loop PI controller PI_d module performs proportional integral operation on the input signal to obtain the corresponding d-axis current loop control signal u do , and sent to the d-axis current loop disturbance observer DO_d module and the d-axis current dynamic module at the same time;

[0062] The d-axis current loop disturbance observer DO_d module is based on the d-axis current loop control signal u do and the feedback d-axis current signal i d , get the disturbance estimate of the d-axis current loop And sent to the d-axis current dynamic module;

[0063] The q-axis current dynamic module is based on the input q-axis signal and q-axis current loop disturbance f q, the response is the q-axis current signal i q , and sent to the q-axis current tracking error module, the q-axis current loop disturbance observer DO_q module and the speed dynamic module at the same time;

[0064] The d-axis current dynamic module is based on the input d-axis signal and the d-axis current loop disturbance f d , the response is the d-axis current signal i d , and sent to the d-axis current tracking error module and the d-axis current loop disturbance observer DO_q module at the same time;

[0065] The q-axis current signal i input by the speed dynamic module q and the velocity loop disturbance f d , the response is the speed signal ω m , and sent to the speed tracking error module and the speed loop disturbance observer DO_m module at the same time.

[0066] A permanent magnet synchronous motor cascade control system and parameter setting method based on an observer, the method is executed by the above system, and specifically comprises the following steps:

[0067] Step 1: Establish the basic dynamic equations of the permanent magnet synchronous motor in the two-phase synchronous rotating orthogonal coordinate system.

[0068] First, based on the mathematical model of the permanent magnet synchronous motor in the three-phase stationary ABC coordinate system, the dynamic equations of the permanent magnet synchronous motor in the two synchronous rotating orthogonal dq coordinate systems are obtained through vector transformation as shown below:

[0069]

[0070] Among them, u d and u q are the voltages of the d-axis and q-axis stator windings respectively; R s is the resistance of the stator winding; i d and i q are the currents of the d-axis and q-axis stator windings respectively; L d and L q are the inductances of the d-axis and q-axis stator windings respectively; d / dt is the differential operator; ψ f is the permanent magnet flux; T e is the electromagnetic torque; p n is the number of magnetic pole pairs; J is the moment of inertia; F is the viscous friction coefficient; T m is the load torque disturbance; ω e and ω m are the electrical angular velocity and the mechanical angular velocity respectively, and satisfy ω e =p n ω m .

[0071] Secondly, the present invention takes the surface-mounted permanent magnet synchronous motor as the research object, which satisfies the constraint relationship L d =L q =L s (L s is the inductance of the stator winding). Therefore, the mathematical model of the permanent magnet synchronous motor can be simplified to the electrical dynamic equation shown below:

[0072]

[0073] And the corresponding mechanical dynamic equation, namely

[0074]

[0075] Among them, K T =3p n ψ f / 2 is the electromagnetic torque coefficient.

[0076] Then, according to equation (5), with ω e Multiply L s i q , L s i d and ψ f The cross-coupled back electromotive force of the d-axis and q-axis is formed respectively. e For current i d and i q In order to avoid the influence of the back electromotive force, the present invention models the back electromotive force as a disturbance of the current loop. Therefore, the current dynamics are as follows:

[0077]

[0078] Among them, f d =-ω e L s i q and f q =ω e (L s i d +ψ f ) are the current loop disturbances of the d-axis and q-axis respectively.

[0079] Finally, considering that the output of the speed outer loop is the q-axis given signal, and the mechanical dynamic equation (6) contains the q-axis current signal i q Therefore, the error between them is introduced into the mechanical dynamic equation as shown below:

[0080]

[0081] Among them, f m =(T m+K T e q ) / K T is the velocity loop disturbance, and is the q-axis current tracking error, is the given q-axis current command.

[0082] Step 2: Construct a new disturbance observer.

[0083] First, based on the Figure 1 As shown in the block diagram of the permanent magnet synchronous motor cascade control system based on the disturbance observer of the present invention, each loop has the same structure and form. Therefore, the control law satisfies the following relationship:

[0084]

[0085] in, and are the disturbance estimates of the d-axis and q-axis current loops respectively; is the disturbance estimate of the speed loop.

[0086] Secondly, based on the nominal parameters (indicated by the additional subscript “n”) and information of the dynamic systems (7) to (9), a new disturbance observer is designed as follows:

[0087]

[0088] Among them, DO_d and DO_q are the disturbance observers of the d-axis and q-axis current loops respectively; DO_m is the disturbance observer of the speed loop; ξ d and q are the observer variables of the d-axis and q-axis current loops respectively; m is the observer variable of the speed loop; l c and l s are the observer gains of the current loop and speed loop respectively.

[0089] Then, by combining equations (7) to (10) and the novel disturbance observer (11) to (13) constructed above, we can obtain the following transfer function:

[0090]

[0091]

[0092] Wherein, “(s)” represents the Laplace transform of the corresponding variable, and “s” is the Laplace transform operator.

[0093] Finally, by combining the dynamic system (7)~(9) and the constructed new disturbance observer (11)~(13), we can get the augmented system as shown below:

[0094]

[0095] Among them, ε c =1 / l c and ε s =1 / l s are the singular perturbation parameters of the current loop and velocity loop augmented system respectively.

[0096] According to the famous singular perturbation theory, let ε c = 0 and ε s = 0, we can get the quasi-steady-state solution of the boundary layer system of the augmented system (17)~(19). From this, we can get the quasi-steady-state equation as follows:

[0097]

[0098] Step 3: Determine the cascade control law based on the nominal system.

[0099] For the nominal systems (20) to (22), the PI controllers for the current loop and the speed loop are designed as follows:

[0100]

[0101] Among them, u do and u qo are the d-axis and q-axis current loop control signals respectively; u m is the speed loop control signal; e d and e q are the d-axis and q-axis current tracking errors respectively; e m is the speed tracking error; K Pc =ω c L sn and K Ic =ω c R sn are the proportional and integral gains of the current loop, ω c is the bandwidth of the current loop; K Ps =ω s J n / K Tn and K Is =ω s F n / K Tn are the proportional and integral gains of the speed loop, ω s is the bandwidth of the speed loop.

[0102] Since the current dynamics of the permanent magnet synchronous motor are much faster than the mechanical dynamics, it satisfies the following relationship:

[0103] T cn <<T sn (twenty four)

[0104] Among them, T cn =L sn / R sn and T sn =J n / F n are the nominal electrical and mechanical time constants of the current loop and speed loop respectively.

[0105] Based on the analysis of the observer gain in step 2 and the time constant constraint shown in (24), the following method for tuning the observer and controller parameters is given:

[0106]

[0107] Among them, T s To interrupt the execution cycle.

[0108] From (25), it can be seen that the present invention only needs to give the bandwidth ω of the current loop c , it is possible to adjust all parameters of the disturbance observer and cascade controller, reducing the difficulty and number of parameter adjustment, and has the advantages of easy design and implementation. In addition, since the observer gains of the current loop and the speed loop are both greater than their corresponding bandwidths, the rapid convergence of the observer is guaranteed, and high-precision estimation and effective feedforward compensation can be performed for unknown disturbances and uncertainties in motor parameters.

[0109] In this implementation, in order to verify the effectiveness and advantages of the designed system, take T s =0.1ms, the inverter switching frequency is 10kHz.

[0110] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0111] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

[0112] The above-described embodiments of the present application do not constitute a limitation on the protection scope of the present application.

Claims

1. A permanent magnet synchronous motor cascade control system based on an observer, characterized in that: The system includes a speed tracking error module, a speed loop PI controller PI_m module, a speed loop disturbance observer DO_m module, a q-axis current tracking error module, a q-axis current loop PI controller PI_q module, a q-axis current loop disturbance observer DO_q module, a d-axis current tracking error module, a d-axis current loop PI controller PI_d module, a d-axis current loop disturbance observer DO_d module, a q-axis current dynamic module, a d-axis current dynamic module, and a speed dynamic module; The speed tracking error module is based on the given speed command and the feedback speed signal ω m , calculate the difference to get the speed tracking error e m , and sent to the speed loop PI controller PI_m module; The speed loop PI controller PI_m module performs proportional integral operation on the input signal to obtain the corresponding speed loop control signal u m , and sent to the speed loop disturbance observer DO_m module and the q-axis current tracking error module at the same time; The speed loop disturbance observer DO_m module is based on the speed loop control signal u m and the feedback speed signal ω m , get the disturbance estimate of the velocity loop And sent to the q-axis current tracking error module; The q-axis current tracking error module is based on the given q-axis current command And the feedback q-axis current signal i q , calculate the difference to get the q-axis current tracking error e q , and sent to the q-axis current loop PI controller PI_q module; The q-axis current loop PI controller PI_q module performs proportional integral operation on the input signal to obtain the corresponding q-axis current loop control signal u qo , and sent to the q-axis current loop disturbance observer DO_q module and the q-axis current dynamic module at the same time; The q-axis current loop disturbance observer DO_q module is based on the q-axis current loop control signal u qo And the feedback q-axis current signal i q , get the disturbance estimate of the q-axis current loop And sent to the q-axis current dynamic module; The d-axis current tracking error module is based on the given d-axis current command and the feedback d-axis current signal i d , calculate the difference to get the d-axis current tracking error e d , and sent to the d-axis current loop PI controller PI_d module; The d-axis current loop PI controller PI_d module performs proportional integral operation on the input signal to obtain the corresponding d-axis current loop control signal u do , and sent to the d-axis current loop disturbance observer DO_d module and the d-axis current dynamic module at the same time; The d-axis current loop disturbance observer DO_d module is based on the d-axis current loop control signal u do and the feedback d-axis current signal i d , get the disturbance estimate of the d-axis current loop And sent to the d-axis current dynamic module; The q-axis current dynamic module is based on the input q-axis signal and q-axis current loop disturbance f q , the response is the q-axis current signal i q , and sent to the q-axis current tracking error module, the q-axis current loop disturbance observer DO_q module and the speed dynamic module at the same time; The d-axis current dynamic module is based on the input d-axis signal and the d-axis current loop disturbance f d , the response is the d-axis current signal i d , and sent to the d-axis current tracking error module and the d-axis current loop disturbance observer DO_q module at the same time; The q-axis current signal i input by the speed dynamic module q and the velocity loop disturbance f d , the response is the speed signal ω m , and sent to the speed tracking error module and the speed loop disturbance observer DO_m module at the same time.

2. A parameter setting method for a permanent magnet synchronous motor cascade control based on an observer, the method being executed by the permanent magnet synchronous motor cascade control system based on an observer according to claim 1, characterized in that: The method comprises: Step 1: Establish the basic dynamic equation of the permanent magnet synchronous motor in a two-phase synchronous rotating orthogonal coordinate system; Step 2: construct a new disturbance observer; Step 3: Determine the cascade control law based on the nominal system.

3. The method for parameter setting of cascade control of permanent magnet synchronous motor based on observer according to claim 2, characterized in that: The basic dynamic equation of the permanent magnet synchronous motor in the two-phase synchronous rotating orthogonal coordinate system in step 1 is: Among them, d / dt is the differential operator; i d and i q are the currents of the d-axis and q-axis stator windings respectively; R s and L s are the resistance and inductance of the stator winding respectively; u d and u q are the voltages of the d-axis and q-axis stator windings respectively; f d =-ω e L s i q and f q =ω e (L s i d +ψ f ) are the current loop disturbances of the d-axis and q-axis respectively; ψ f is the permanent magnet flux; F is the viscous friction coefficient; J is the moment of inertia; K T =3p n ψ f / 2 is the electromagnetic torque coefficient; p n is the number of magnetic poles; f m =(T m +K T e q ) / K T is the velocity loop disturbance; T m is the load torque disturbance; is the q-axis current tracking error, is the given q-axis current command; ω e and ω m are the electrical angular velocity and the mechanical angular velocity respectively, and satisfy ω e =p n ω m .

4. The method for parameter setting of cascade control of a permanent magnet synchronous motor based on an observer according to claim 3, characterized in that: In step 1, to decouple ω e For current i d and i q The back EMF is modeled as a disturbance of the current loop; the q-axis current tracking error e q Introduced into the mechanical dynamic equation, it forms a load torque disturbance T m The modeled current loop and speed loop disturbances have the same gain as the control input.

5. The method for parameter setting of cascade control of permanent magnet synchronous motor based on observer according to claim 2, characterized in that: The new disturbance observer constructed in step 2 is as follows: Among them, DO_d and DO_q are the disturbance observers of the d-axis and q-axis current loops respectively; DO_m is the disturbance observer of the speed loop; ξ d and q are the observer variables of the d-axis and q-axis current loops respectively; m is the observer variable of the speed loop; l c and l s are the observer gains for the current loop and the speed loop, respectively; parameters containing an additional subscript "n" indicate nominal parameters.

6. The method for parameter setting of cascade control of permanent magnet synchronous motor based on observer according to claim 5, characterized in that: The new disturbance observer constructed in step 2 has the following transfer function: Where "(s)" represents the Laplace transform of the corresponding variable, and "s" is the Laplace transform operator; The disturbance observer is essentially a first-order low-pass filter that can achieve accurate real-time estimation and compensation of unknown disturbances, and the convergence speed is proportional to the observer gain.

7. The method for parameter setting of cascade control of a permanent magnet synchronous motor based on an observer according to claim 5, characterized in that: In step 2, the dynamic system equations and the constructed new disturbance observer are combined to obtain the following augmented system: Among them, ε c =1 / l c and ε s =1 / l s are the singular perturbation parameters of the current loop and velocity loop augmented systems respectively; According to the famous singular perturbation theory, when the observer gain is large enough, the augmented system is equivalent to the quasi-steady-state equation shown below: The novel disturbance observer makes the augmented system including the observer dynamics behave as a nominal system, and the control performance is not affected by unknown disturbances and motor parameter uncertainties.

8. The method for parameter setting of cascade control of a permanent magnet synchronous motor based on an observer according to claim 2, characterized in that: The PI controller designed in step 3 is as follows: Among them, u do and u qo are the d-axis and q-axis current loop control signals respectively; u m is the speed loop control signal; e d and e q are the d-axis and q-axis current tracking errors respectively; e m is the speed tracking error; K Pc =ω c L sn and K Ic =ω c R sn are the proportional and integral gains of the current loop, ω c is the bandwidth of the current loop; K Ps =ω s J n / K Tn and K Is =ω s F n / K Tn are the proportional and integral gains of the speed loop, ω s is the bandwidth of the speed loop.

9. The method for parameter setting of cascade control of a permanent magnet synchronous motor based on an observer according to claim 2, characterized in that: For the observer gain in step 2 and the controller parameters in step 3, the parameter tuning method is as follows: Among them, T s is the interrupt execution cycle; T cn =L sn / R sn is the nominal electrical time constant of the current loop.

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