A Sensorless Control Method and Control System for Permanent Magnet Synchronous Motor

Abstract

The present invention discloses a position sensorless control method and control system for a permanent magnet synchronous motor, belonging to the field of motor control technology. The method comprises: estimating rotor information through an EKF; obtaining an estimated rotor speed based on the rotor position and rotor speed; using the difference between the rotor speed and the speed feedback as the input variable of the rotor PI controller; constructing an observer using the rotor speed and a sliding mode variable structure control function obtained using a sliding mode observer, determining a switching function and a switching surface, obtaining a control function, and using both as input variables of a flux linkage PI controller; outputting d-axis and q-axis reference signals in sequence according to the flux linkage PI controller and the rotor PI controller; obtaining a three-phase stator voltage by subjecting the reference signal to a Park inverse transform and an improved Clark inverse transform; and performing SVPWM modulation on the three-phase stator voltage to enable the permanent magnet synchronous motor to obtain a circular magnetic field with a constant amplitude, thereby ultimately causing the motor to operate. The present invention has the technical effects of low cost and high control accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and more particularly to a position sensorless control method and control system for a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motor (PMSM) has many advantages such as small size, light weight, high power density, high power factor, high efficiency, high torque / inertia ratio, high reliability and easy maintenance, and is widely used.

[0003] In traditional permanent magnet synchronous motor control methods, a rotor position sensor is usually installed on the PMSM rotor shaft to monitor load speed information and position feedback signals. However, this approach will inevitably bring many problems. For example, due to the limitations of the working environment, corresponding requirements are put forward for environmental indicators such as temperature, vibration, and humidity; the configuration of the rotor position sensor will increase the system investment in terms of cost and maintenance expenses; the reliability of the rotor position sensor needs to be improved, which will affect the overall operational stability of the system.

[0004] Based on this, how to provide a position sensorless control method and control system for a permanent magnet synchronous motor is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a position sensorless control method and control system for a permanent magnet synchronous motor to solve the technical problems existing in the above-mentioned prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a position sensorless control method for a permanent magnet synchronous motor, comprising the following steps:

[0008] S100: Estimating rotor information through EKF, where the rotor information includes rotor position and rotor speed;

[0009] S200: Obtaining an estimated rotor speed according to the rotor position and the rotor speed;

[0010] S300: Using the difference between the rotor speed and the speed feedback as an input variable of a rotor PI controller;

[0011] S400: Using the rotor speed as an input variable, a sliding mode variable structure control function is obtained by using a sliding mode observer to construct an observer, a switching function and a switching surface are determined, and a control function is obtained, which are used as input variables of a flux linkage PI controller;

[0012] S500: Outputting d-axis and q-axis reference signals in sequence according to the flux linkage PI controller and the rotor PI controller;

[0013] S600: The reference signal is sequentially subjected to Park inverse transformation and improved Clark inverse transformation to obtain a three-phase stator voltage;

[0014] S700: Perform SVPWM modulation on the three-phase stator voltage to enable the permanent magnet synchronous motor to obtain a circular magnetic field with a constant amplitude, and ultimately cause the motor to operate.

[0015] Preferably, the step S100 includes the following steps:

[0016] S110: Establish the EKF model of PMSM:

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] Where, L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient;

[0022] S120: Determine the state variables and input variables as follows:

[0023] ;

[0024] ;

[0025] ;

[0026] S130: Establish linear equation:

[0027] ;

[0028] in:

[0029] ;

[0030] S140: Measurement -β coordinate system, and use it as the output variable to establish the measurement equation:

[0031] ;

[0032] in, ;

[0033] S150: Get The corresponding Jacobian matrix:

[0034] ;

[0035] S160: Get The corresponding Jacobian matrix:

[0036] ;

[0037] S170: Based on steps S110 - S160 , a rotor position and speed simulation model is established, and a rotor position signal and a rotor speed signal are output.

[0038] Preferably, the step S400 includes the following steps:

[0039] S410: Constructing a sliding mode observer:

[0040] ;

[0041] in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function;

[0042] S420: Determine the switching function and switching surface:

[0043] ;

[0044] ;

[0045] in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ;

[0046] S430: Solve the control function:

[0047] ;

[0048] Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, it is an adjustable parameter;

[0049] S440: The rotor speed and the solved control function are used as input variables of a flux linkage PI controller.

[0050] Preferably, the S500 includes:

[0051] The flux linkage PI controller outputs the d-axis reference signal u d ;

[0052] The rotor PI controller outputs the q-axis reference signal u q .

[0053] The S600 includes:

[0054] S610: After Park inverse transform:

[0055] The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get:

[0056] ;

[0057] ;

[0058] in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor;

[0059] S620: Improved Clark inverse transform:

[0060] ;

[0061] 、 、 is the three-phase stator voltage.

[0062] In another aspect, the present invention provides a position sensorless control system for a permanent magnet synchronous motor, comprising:

[0063] An estimation module, configured to estimate rotor information using an EKF, wherein the rotor information includes rotor position and rotor speed;

[0064] a calculation module, connected to the estimation module, configured to obtain an estimated rotor speed based on the rotor position and the rotor speed;

[0065] a rotor PI control module, connected to the calculation module, and configured to use the difference between the rotor speed and the speed feedback as an input variable of the rotor PI controller;

[0066] a flux linkage PI control module, connected to the calculation module, for taking the rotor speed as an input variable, using a sliding mode observer to obtain a sliding mode variable structure control function to construct an observer, determine a switching function and a switching surface, and obtain a control function, which is also used as an input variable of the flux linkage PI controller;

[0067] an output module, connected to the rotor PI control module and the flux PI control module, and configured to sequentially output reference signals of the d-axis and the q-axis according to the flux PI controller and the rotor PI controller;

[0068] a processing module, connected to the output module, for sequentially subjecting the reference signal to Park inverse transformation and improved Clark inverse transformation to obtain a three-phase stator voltage;

[0069] The modulation module is connected to the processing module and is used to perform SVPWM modulation on the three-phase stator voltage so that the permanent magnet synchronous motor obtains a circular magnetic field with constant amplitude and finally causes the motor to run.

[0070] Preferably, the estimation module includes:

[0071] The first building unit is used to build the EKF model of PMSM:

[0072] ;

[0073] ;

[0074] ;

[0075] ;

[0076] Where, L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient;

[0077] Determination unit, used to determine the state variables and input variables as:

[0078] ;

[0079] ;

[0080] ;

[0081] The second building unit is used to build the linear equation:

[0082] ;

[0083] in:

[0084] ;

[0085] The third building unit is used to measure -β coordinate system, and use it as the output variable to establish the measurement equation:

[0086] ;

[0087] in, ;

[0088] The first calculation unit is used to obtain The corresponding Jacobian matrix:

[0089] ;

[0090] The second calculation unit is used to obtain The corresponding Jacobian matrix:

[0091] ;

[0092] An output unit is used to establish a rotor position and speed simulation model based on the first establishing unit, the determining unit, the second establishing unit, the third establishing unit, the first calculating unit and the second calculating unit, and output a rotor position signal and a rotor speed signal.

[0093] Preferably, the magnetic flux PI control module includes:

[0094] The first building block is used to build a sliding mode observer:

[0095] ;

[0096] in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function;

[0097] The second determining unit is used to determine the switching function and the switching surface:

[0098] ;

[0099] ;

[0100] in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ;

[0101] The third calculation unit is used to solve the control function:

[0102] ;

[0103] Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, is an adjustable parameter,

[0104] The input unit is used to use the rotor speed and the solved control function as input variables of the flux linkage PI controller.

[0105] Preferably, the output module includes:

[0106] The first output unit is used for the flux linkage PI controller to output the d-axis reference signal u d ;

[0107] The second output unit is used for the rotor PI controller to output the q-axis reference signal u q .

[0108] Preferably, the processing module includes:

[0109] The first transformation unit is used for Park inverse transformation:

[0110] The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get:

[0111] ;

[0112] ;

[0113] in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor;

[0114] The second transform unit is used for the improved Clark inverse transform:

[0115] ;

[0116] 、 、 is the three-phase stator voltage.

[0117] As can be seen from the above technical solution, compared with the prior art, the present invention provides a position sensorless control method and control system for a permanent magnet synchronous motor. By obtaining the motor's electrical parameters, the rotor position parameter motion characteristics are derived. This eliminates the need to purchase expensive rotor position sensors, reduces the cost of building a control system, improves environmental interference resistance, and eliminates the need for motor modification, allowing the motor to operate according to designed operating conditions without being affected by the additional rotor position sensor. The method cleverly integrates intelligent algorithms with motor control, effectively resists load disturbances, outputs relatively accurate estimates, and achieves more precise control of the magnetic synchronous motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0119] Figure 1 is a flow chart of the method of the present invention;

[0120] Figure 2 Schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0121] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0122] See attached Figure 1As shown, an embodiment of the present invention discloses a position sensorless control method for a permanent magnet synchronous motor, comprising the following steps:

[0123] S100: rotor information estimated by EKF, including rotor position and rotor speed;

[0124] S200: Obtaining an estimated rotor speed based on the rotor position and the rotor speed;

[0125] S300: taking the difference between the rotor speed and the speed feedback as the input variable of the rotor PI controller;

[0126] S400: Using the rotor speed as an input variable, a sliding mode variable structure control function is obtained by using a sliding mode observer to construct an observer, a switching function and a switching surface are determined, and a control function is obtained, which is also used as an input variable of a flux linkage PI controller;

[0127] S500: Outputting d-axis and q-axis reference signals in sequence according to the flux linkage PI controller and the rotor PI controller;

[0128] S600: The reference signal is sequentially subjected to Park inverse transformation and improved Clark inverse transformation to obtain the three-phase stator voltage;

[0129] S700: Perform SVPWM modulation on the three-phase stator voltage to enable the permanent magnet synchronous motor to obtain a circular magnetic field with a constant amplitude, and ultimately cause the motor to operate.

[0130] In a specific embodiment, S100 includes the following steps:

[0131] S110: Establish the EKF model of PMSM:

[0132] ;

[0133] ;

[0134] ;

[0135] ;

[0136] Where, L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient;

[0137] Among them, this embodiment adopts a non-salient pole PMSM. Before establishing the EKF model of PMSM, first - The coordinate system obtains the rotor of the three-phase PMSM - Stator voltage equation, stator flux equation and electromagnetic torque equation in the coordinate system.

[0138] S120: Determine the state variables and input variables as follows:

[0139] ;

[0140] ;

[0141] ;

[0142] S130: Establish linear equation:

[0143] ;

[0144] in:

[0145] ;

[0146] S140: Measurement -β coordinate system, and use it as the output variable to establish the measurement equation:

[0147] ;

[0148] in, ;

[0149] S150: Get The corresponding Jacobian matrix:

[0150] ;

[0151] S160: Get The corresponding Jacobian matrix:

[0152] ;

[0153] S170: Based on steps S110 - S160 , a rotor position and speed simulation model is established, and a rotor position signal and a rotor speed signal are output.

[0154] In a specific embodiment, S400 includes the following steps:

[0155] S410: Constructing a sliding mode observer:

[0156] ;

[0157] in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function;

[0158] S420: Determine the switching function and switching surface:

[0159] ;

[0160] ;

[0161] in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ;

[0162] S430: Solve the control function:

[0163] ;

[0164] Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, is an adjustable parameter,

[0165] S440: The rotor speed and the solved control function are used as input variables of a flux linkage PI controller.

[0166] Specifically, traditional position estimation methods based on the PMSM's fundamental equations include the back-EMF method and the flux linkage method. Both methods suffer from computational blind spots. Specifically, when the PMSM is operating at low speeds, the induced back-EMF is very small and easily overwhelmed by interference signals, resulting in large errors. This invention uses an EKF model of the PMSM to rapidly estimate the motor's rotor position and speed, improving estimation accuracy. Furthermore, a sliding-mode observer accelerates the response of the load torque and current, improving the motor's speed regulation during sudden load changes.

[0167] In a specific embodiment, S500 includes:

[0168] The flux PI controller outputs the reference signal u of the d-axis d ;

[0169] The rotor PI controller outputs the reference signal u of the q axis q .

[0170] In a specific embodiment, S600 includes:

[0171] S610: After Park inverse transform:

[0172] The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get:

[0173] ;

[0174] ;

[0175] in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor;

[0176] S620: Improved Clark inverse transform:

[0177] ;

[0178] 、 、 is the three-phase stator voltage.

[0179] Specifically, since the back EMF in the sliding mode observer also tracks the actual motor back EMF value, it can be extracted through a filter.

[0180] More specifically, the present invention simplifies the algorithm for determining the sign of the three-phase voltage value by using Park inverse transformation and improved Clark inverse transformation. 、 、 The size of the sign can determine the sector where the voltage vector is located at this time, and then directly give the corresponding basic voltage vector action time T1 / T2, and this value is proportional to 、 、 The values of two phases greatly simplify the algorithm process of conventional methods such as linear combination method, and at the same time have the technical effect of effectively reducing the current fluctuation of the motor.

[0181] See attached Figure 2 As shown, on the other hand, the present invention provides a permanent magnet synchronous motor position sensorless control system, comprising:

[0182] An estimation module is used to estimate the rotor information through EKF, where the rotor information includes the rotor position and rotor speed;

[0183] a calculation module, connected to the estimation module, for obtaining an estimated rotor speed according to the rotor position and the rotor speed;

[0184] A rotor PI control module is connected to the calculation module and is used to use the difference between the rotor speed and the speed feedback as an input variable of the rotor PI controller;

[0185] The flux linkage PI control module is connected to the calculation module and is used to take the rotor speed as the input variable, use the sliding mode observer to obtain the sliding mode variable structure control function to construct the observer, determine the switching function and switching surface, and obtain the control function, which is also used as the input variable of the flux linkage PI controller;

[0186] An output module is connected to the rotor PI control module and the flux PI control module, and is used to output reference signals of the d-axis and the q-axis in sequence according to the flux PI controller and the rotor PI controller;

[0187] The processing module is connected to the output module and is used to obtain the three-phase stator voltage by sequentially performing Park inverse transformation and improved Clark inverse transformation on the reference signal;

[0188] The modulation module is connected to the processing module and is used to perform SVPWM modulation on the three-phase stator voltage so that the permanent magnet synchronous motor obtains a circular magnetic field with constant amplitude and finally causes the motor to operate.

[0189] In a specific embodiment, the estimation module includes:

[0190] The first building unit is used to build the EKF model of PMSM:

[0191] ;

[0192] ;

[0193] ;

[0194] ;

[0195] Where, L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient;

[0196] Determination unit, used to determine the state variables and input variables as:

[0197] ;

[0198] ;

[0199] ;

[0200] The second building unit is used to build the linear equation:

[0201] ;

[0202] in:

[0203] ;

[0204] The third building unit is used to measure -β coordinate system, and use it as the output variable to establish the measurement equation:

[0205] ;

[0206] in, ;

[0207] The first calculation unit is used to obtain The corresponding Jacobian matrix:

[0208] ;

[0209] The second calculation unit is used to obtain The corresponding Jacobian matrix:

[0210] ;

[0211] An output unit is used to establish a rotor position and speed simulation model based on the first establishing unit, the determining unit, the second establishing unit, the third establishing unit, the first calculating unit and the second calculating unit, and output a rotor position signal and a rotor speed signal.

[0212] In a specific embodiment, the flux linkage PI control module includes:

[0213] The first building block is used to build a sliding mode observer:

[0214] ;

[0215] in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function;

[0216] The second determining unit is used to determine the switching function and the switching surface:

[0217] ;

[0218] ;

[0219] in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ;

[0220] The third calculation unit is used to solve the control function:

[0221] ;

[0222] Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, is an adjustable parameter, input unit, used to take the rotor speed and the solved control function as input variables of the flux PI controller.

[0223] In a specific embodiment, the output module includes:

[0224] The first output unit is used for the flux linkage PI controller to output the reference signal u of the d-axis d ;

[0225] The second output unit is used for the rotor PI controller to output the reference signal u of the q axis q .

[0226] In a specific embodiment, the processing module includes:

[0227] The first transformation unit is used for Park inverse transformation:

[0228] The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get:

[0229] ;

[0230] ;

[0231] in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor;

[0232] The second transform unit is used for the improved Clark inverse transform:

[0233] ;

[0234] 、 、 is the three-phase stator voltage.

[0235] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0236] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A position sensorless control method for a permanent magnet synchronous motor, characterized in that: The following steps are involved: S100: Estimating rotor information through EKF, where the rotor information includes rotor position and rotor speed; S200: Obtaining an estimated rotor speed according to the rotor position and the rotor speed; S300: Using the difference between the rotor speed and the speed feedback as an input variable of a rotor PI controller; S400: Using the rotor speed as an input variable, a sliding mode variable structure control function is obtained by using a sliding mode observer to construct an observer, a switching function and a switching surface are determined, and a control function is obtained, which are used as input variables of a flux linkage PI controller; S5 00: The flux PI controller and the rotor PI controller sequentially output the reference signals of the d-axis and the q-axis; S600: The reference signal is sequentially subjected to Park inverse transformation and improved Clark inverse transformation to obtain a three-phase stator voltage; S700: Performing SVPWM modulation on the three-phase stator voltage to enable the permanent magnet synchronous motor to obtain a circular magnetic field with a constant amplitude, thereby ultimately causing the motor to operate; The step S400 includes the following steps: S410: Constructing a sliding mode observer: ； in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function; S420: Determine the switching function and switching surface: ； ； in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ; S430: Solve the control function: ； Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, is an adjustable parameter, S440: The rotor speed and the solved control function are used as input variables of a flux linkage PI controller.

2. A position sensorless control method for a permanent magnet synchronous motor according to claim 1, characterized in that: The S100 includes the following steps: S110: Establish the EKF model of PMSM: ； ； ； ； Where L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient; S120: Determine the state variables and input variables as follows: ； ； ； S130: Establish linear equation: ； in: ； S140: Measurement -β coordinate system, and use it as the output variable to establish the measurement equation: ； in, ; S150: Get The corresponding Jacobian matrix: ； S160: Get The corresponding Jacobian matrix: ； S170: Based on steps S110 - S160 , a rotor position and speed simulation model is established, and a rotor position signal and a rotor speed signal are output.

3. A position sensorless control method for a permanent magnet synchronous motor according to claim 1, characterized in that: The S500 includes: The flux linkage PI controller outputs the d-axis reference signal u d ; The rotor PI controller outputs the q-axis reference signal u q .

4. A position sensorless control method for a permanent magnet synchronous motor according to claim 1, characterized in that: The S600 includes: S610: After Park inverse transform: The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get: ； ； in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor; S620: Improved Clark inverse transform: ； 、 、 is the three-phase stator voltage.

5. A permanent magnet synchronous motor position sensorless control system, characterized in that: include: An estimation module, configured to estimate rotor information using an EKF, wherein the rotor information includes rotor position and rotor speed; a calculation module, connected to the estimation module, configured to obtain an estimated rotor speed based on the rotor position and the rotor speed; a rotor PI control module, connected to the calculation module, and configured to use the difference between the rotor speed and the speed feedback as an input variable of the rotor PI controller; a flux linkage PI control module, connected to the calculation module, for taking the rotor speed as an input variable, using a sliding mode observer to obtain a sliding mode variable structure control function to construct an observer, determining a switching function and a switching surface, and obtaining a control function, which are used as input variables of a flux linkage PI controller; an output module, connected to the rotor PI control module and the flux PI control module, and configured to sequentially output reference signals of the d-axis and the q-axis according to the flux PI controller and the rotor PI controller; a processing module, connected to the output module, for sequentially subjecting the reference signal to Park inverse transformation and improved Clark inverse transformation to obtain a three-phase stator voltage; A modulation module, connected to the processing module, is used to perform SVPWM modulation on the three-phase stator voltage so that the permanent magnet synchronous motor obtains a circular magnetic field with a constant amplitude and ultimately causes the motor to operate; Wherein, the magnetic flux PI control module includes: The first building block is used to build a sliding mode observer: ； in , , is the control function, is the equivalent control function, is the sigmoid function, is the feedback gain coefficient of the equivalent control function; The second determining unit is used to determine the switching function and the switching surface: ； ； in, Estimate the stator current value, is the actual measured current value of the stator, s is the switching function, ; The third calculation unit is used to solve the control function: ； Among them, k is the gain value of the control function, that is, the sliding mode gain value, >0, is an adjustable parameter, The input unit is used to use the rotor speed and the solved control function as input variables of the flux linkage PI controller.

6. A permanent magnet synchronous motor position sensorless control system according to claim 5, characterized in that: The estimation module comprises: The first building unit is used to build the EKF model of PMSM: ； ； ； ； Where L is the inductance of the permanent magnet synchronous motor, for Shaft current, for Shaft stator voltage, for Shaft current, for Shaft stator voltage, R s is the stator resistance of the permanent magnet synchronous motor, is the air gap permeability per unit area, is the rotor mechanical angular velocity, d is the rotor friction coefficient; Determination unit, used to determine the state variables and input variables as: ； ； ； The second building unit is used to build the linear equation: ； in: ； The third building unit is used to measure - The stator current value of the coordinate system is used as the output variable to establish the measurement equation: ； in, ; The first calculation unit is used to obtain The corresponding Jacobian matrix: ； The second calculation unit is used to obtain The corresponding Jacobian matrix: ； An output unit is used to establish a rotor position and speed simulation model based on the first establishing unit, the determining unit, the second establishing unit, the third establishing unit, the first calculating unit and the second calculating unit, and output a rotor position signal and a rotor speed signal.

7. A permanent magnet synchronous motor position sensorless control system according to claim 5, characterized in that: The output module includes: The first output unit is used for the flux linkage PI controller to output the d-axis reference signal u d ; The second output unit is used for the rotor PI controller to output the q-axis reference signal u q .

8. A position sensorless control system for a permanent magnet synchronous motor according to claim 5, characterized in that: The processing module includes: The first transformation unit is used for Park inverse transformation: The coordinate system of the two phases a and β being stationary is transformed into the coordinate system of the two phases d and q being rotating, and we get: ； ； in, for Shaft current, for Shaft current, is the stator resistance, is the rotor mechanical speed value, is the rotor flux, is the electromagnetic position of the rotor; The second transform unit is used for the improved Clark inverse transform: ； 、 、 is the three-phase stator voltage.

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