Permanent magnet synchronous motor dead zone compensation method based on nonlinear flux observer

Abstract

The invention belongs to the technical field of AC motor transmission control, and relates to a permanent magnet synchronous motor dead zone compensation method based on a nonlinear flux observer. Measuring a motor induction current under a natural coordinate system, and obtaining an alpha-beta axis current through conversion; a non-linear flux observer in an alpha-beta coordinate system is used as a position observation model to obtain an actual rotor position estimation value, a rotating speed ring is formed, and sensorless control of the permanent magnet synchronous motor is achieved; constructing a q-axis voltage disturbance observer by measuring the phase voltage output by the inverter; taking the output of the q-axis disturbance observer as the input of a dead time calculation module to obtain a dead time estimation value; and according to the estimated value, calculating and obtaining a dead-zone compensation voltage, and compensating the output phase voltage of the inverter to realize dead-zone compensation. On the basis of a non-linear flux observer, a position-free control closed-loop structure is constructed, and instruction voltage is corrected, so that the influence of inverter dead time on the permanent magnet synchronous motor is reduced, and the position-free control performance is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of AC motor transmission control and relates to a permanent magnet synchronous motor dead zone compensation method based on a nonlinear flux observer. Background Art

[0002] Aircraft-borne pump loads include a variety of pump equipment, which are mainly used for aircraft propulsion, life support, engine operation and maintenance, etc., and generally require high power, light weight, small size, fast response time and high control accuracy. With the rapid development of aerospace, permanent magnet synchronous motors with high power density and low energy consumption have become a research hotspot for aircraft-borne pump loads, and existing airborne pump loads all use mechanical position / speed sensors to obtain the position or speed signal of the motor. In the actual operation of aircraft, airborne pump loads work in a high temperature, high pressure and high electromagnetic interference environment, which can easily cause mechanical sensors to fail, thereby causing traction system failures and causing large torque shocks. In severe cases, it will damage motor-related components, resulting in insufficient output and endangering aviation safety. Position sensorless drive technology fundamentally eliminates this safety hazard, and has the advantages of strong anti-interference ability, high integration and long service life. Compared with conventional flux observers, nonlinear flux observers have the characteristics of wide speed range applicability because their state variables are independent of speed, and have a simple structure and are easy to implement.

[0003] During the flight of an aircraft, different altitudes and speeds require different pump devices, and the working requirements of the same pump device are also different. Due to the nonlinear factors of the inverter, the utilization rate of the bus voltage cannot reach the maximum, which leads to a decrease in the motor control performance, which is particularly obvious when the motor is running alternately in forward and reverse rotation. When there is a dead zone, the motor response current waveform deteriorates, resulting in the performance of the nonlinear flux observer being affected and the effect of estimating the rotor position being deteriorated. Therefore, in a permanent magnet traction system with a permanent magnet synchronous motor as an aviation pump load, using a nonlinear flux observer as a position observer and combining it with a dead zone compensation method has important practical significance for improving the performance of position sensorless control. Summary of the invention

[0004] Purpose of the Invention

[0005] The purpose of the present invention is to provide a permanent magnet synchronous motor position sensorless dead zone compensation method based on a nonlinear flux observer, by which the stator flux is estimated through the αβ axis current, so that the rotor position angle and the rotation speed are estimated and calculated using the estimated flux, thereby realizing sensorless control of the permanent magnet synchronous motor; in addition, by obtaining the phase voltages of the three phases ABC in the natural coordinate system, the dead zone time is calculated in real time, and then the phase voltages of the three phases ABC are compensated according to the dead zone time, so as to improve the response current waveform, improve the rotor position estimation performance, and optimize the position sensorless control performance of the permanent magnet synchronous motor based on the nonlinear flux observer.

[0006] Technical Solution

[0007] The permanent magnet synchronous motor dead zone compensation method based on nonlinear flux observer is implemented in the following steps:

[0008] Step 1, measure the motor induced current in the ABC coordinate system, and obtain the αβ axis current through Clark transformation;

[0009] Step 2, using the nonlinear flux observer in the αβ coordinate system as the position observation model to obtain the actual rotor position estimation value, thereby forming a speed loop and realizing position sensorless control of the permanent magnet synchronous motor;

[0010] Step 3, constructing a q-axis voltage disturbance observer by measuring the phase voltage output by the inverter;

[0011] Step 4, using the output of the q-axis disturbance observer as the input of the dead time calculation module to obtain the dead time estimation value;

[0012] Step 5, according to the dead time estimation value, calculate and obtain the dead time compensation voltage, compensate the inverter output phase voltage, and realize the permanent magnet synchronous motor position sensorless dead time compensation based on the nonlinear flux observer.

[0013] Furthermore, step 1 is specifically as follows:

[0014] Step 1.1, the three-phase induced current i of the permanent magnet synchronous motor a 、i b 、i c Sampling is performed and Clarke transformation is performed to obtain the α-axis current i α and the β-axis current i β ; Then perform Park transformation on it to obtain the d-axis current i d and q-axis current i q , for the d-axis current i d and q-axis current i q Perform PI adjustment to obtain the d-axis voltage command value u d and q-axis voltage command value u q, and then perform inverse Park transformation to obtain the α-axis voltage command value u α and β-axis voltage command value u β .

[0015] Furthermore, step 2 is specifically as follows:

[0016] Step 2.1, establish a mathematical model of the surface mounted permanent magnet synchronous motor in the αβ coordinate system, as shown in formula (1);

[0017]

[0018] Among them, L and R s are the stator inductance and stator resistance, ω and θ respectively r are the motor angular velocity and rotor position angle, ψ m is the permanent magnet flux, T e is the electromagnetic torque, and P is the number of motor poles.

[0019] Step 2.2, define the state variable x and output y, as shown in equation (2) and equation (3);

[0020]

[0021] By taking the derivative of formula (2), we can get the relationship between formula (2) and formula (3), as shown in formula (4);

[0022]

[0023] Step 2.3, define the vector function η(x), as shown in formula (5);

[0024]

[0025] Combining formula (3), the norm of η(x) is shown in formula (6);

[0026]

[0027] Step 2.4, combining equation (4), equation (5), and equation (6), construct a nonlinear flux observer model, as shown in equation (7);

[0028]

[0029] in, and are the state variable and the derivative of the state variable of the nonlinear flux observer, γ is the observer gain and γ>0;

[0030] Step 2.5, transform equation (3) to obtain equation (8);

[0031]

[0032] Therefore, the sine and cosine components of the estimated rotor position calculated by the observer are obtained as shown in equation (9);

[0033]

[0034] In the formula, To estimate the rotor position.

[0035] Step 2.6, normalize the sine and cosine components containing the estimated rotor position, and calculate through the phase-locked loop to obtain the estimated rotor position and estimated speed This forms a speed loop.

[0036] Furthermore, step 3 is specifically as follows:

[0037] Step 3.1, establish the motor voltage equation in the dq coordinate system, as shown in equation (10);

[0038]

[0039] Among them, u dd =-ωLi q ,u qd =ω(Li d +K E ), K E is the back electromotive force constant.

[0040] When dead zone compensation is not added, the command voltage u d and u q There will be a disturbance voltage in, as shown in formula (11);

[0041]

[0042] After dead zone compensation, equation (11) will change to equation (12);

[0043]

[0044] in, are the d-axis and q-axis disturbance voltages respectively, They are the d-axis and q-axis dead zone compensation voltages respectively.

[0045] Step 3.2, since the q-axis disturbance voltage changes very little and can be ignored, its derivative is always zero, as shown in equation (13);

[0046]

[0047] Therefore, the state equation of the permanent magnet synchronous motor after adding the disturbance voltage is And the output equation y1 is shown in equation (14);

[0048]

[0049] Step 3.3, construct the q-axis disturbance observer, as shown in formula (15);

[0050]

[0051] in, G2 = -Lγ1γ2, γ1 and γ2 are the observer poles.

[0052] Furthermore, step 4 is specifically as follows:

[0053] Step 4.1, to compensate for the dead zone, in the ABC coordinate system, the dead zone compensation voltage is added to the command voltage of the three phases ABC, where the dead zone compensation voltage of phase A is shown in formula (16);

[0054]

[0055] In the formula, is the dead zone compensation voltage of phase A, T c is the dead time, T s is the sampling cycle time, U dc Bus voltage.

[0056] Step 4.2, define the transformation matrix from the ABC coordinate system to the rotation coordinate system as shown in formula (17);

[0057]

[0058] Since the q-axis dead zone compensation voltage has periodic fluctuations, the q-axis maximum dead zone compensation voltage From equation (16) and equation (17), we can get:

[0059]

[0060] Its average It is obtained by integration, as shown in formula (19);

[0061]

[0062] The average value is used instead of the maximum value, as shown in formula (20);

[0063]

[0064] Step 4.3, transform equation (20) to obtain the dead time T c , as shown in formula (21);

[0065]

[0066] Furthermore, step 5 is specifically as follows:

[0067] Step 5.1, let the output of the q-axis disturbance observer in step 3 be Equal to the q-axis average dead zone compensation voltage in step 4 Get estimated dead time As shown in formula (22);

[0068]

[0069] Step 5.2, substitute equation (22) into equation (16) to obtain the estimated dead zone compensation voltage of phase A, as shown in equation (22-1);

[0070]

[0071] Similarly, the estimated dead zone compensation voltage of phases BC is shown in equations (23) and (24);

[0072]

[0073] In step 5.3, the estimated dead zone compensation voltage of phases ABC is added to the three-phase voltage output by the inverter to achieve dead zone compensation.

[0074] Furthermore, the nonlinear flux observer is constructed based on the nonlinear model of the motor and does not rely on the motor back electromotive force model when the motor starts, thereby achieving zero-speed and low-speed starting and load operation of the motor.

[0075] Furthermore, before step 1, the motor control system should satisfy at least two-phase current sampling and bus voltage sampling functions.

[0076] Furthermore, after completing step 5, the feasibility of the method can be verified through simulation modeling or experiments.

[0077] Furthermore, the verification method includes high-speed operating conditions and low-speed operating conditions.

[0078] Furthermore, the high-speed working condition verification method is as follows: when the speed is given to be 8000rpm, when this method is used, the initial load is 0.5Nm, and the load suddenly changes to 2Nm at 1s. After compensating for the dead zone, the time required for the speed fluctuation caused by the load mutation to recover to the steady-state value is significantly reduced; in addition, compared with the waveform without dead zone compensation, the waveform fluctuation of the estimated speed after dead zone compensation is also improved, which is closer to the actual speed.

[0079] Furthermore, the above low-speed working condition verification method is specifically that, given a speed of 200rpm, the load increases with time and reaches a maximum at 0.35s, with a maximum of 2.5Nm. After using this method, the actual rotor position waveform is better than when it is not used, and the actual rotor position curve is closer to a straight line.

[0080] The beneficial effects of this application are:

[0081] The method for compensating the position sensorless dead zone of the permanent magnet synchronous motor based on the nonlinear flux observer realizes the dead zone compensation when controlling the permanent magnet synchronous motor; through the q-axis disturbance observer, the dead zone time is calculated in real time to further ensure the accuracy of the dead zone compensation; the control performance of the permanent magnet synchronous motor without position sensor based on the nonlinear flux observer is improved, and the position estimation accuracy is improved. Under high-speed conditions, the speed fluctuation is significantly improved and the fluctuation becomes smaller. Under low-speed conditions, the rotor position observation is more stable and the load capacity is significantly improved. By compensating the dead zone, the success rate of zero-speed starting is improved, and there is no need to switch to other algorithms at medium and high speeds, ensuring the consistency of the algorithm. The dead zone compensation method provides the q-axis disturbance observer, improves the ability of the permanent magnet synchronous motor to suppress disturbances, improves the control performance of the permanent magnet synchronous motor, and the dead zone compensation method is more robust. The dead zone compensation method can also improve the performance of zero-speed switching during positionless servo control, ensuring that the system is smoother when switching at zero speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 It is a block diagram of the dead zone compensation principle of a permanent magnet synchronous motor based on a nonlinear flux observer of the present invention;

[0083] Figure 2 It is the structural block diagram of nonlinear flux observer;

[0084] Figure 3 This is the dead zone compensation principle block diagram;

[0085] Figure 4 It is a waveform diagram comparing the estimated speed and the actual speed after adding the dead time at a given speed of 8000 rpm;

[0086] Figure 5 This is a waveform diagram comparing the estimated speed and the actual speed after the dead zone is compensated at a given speed of 8000 rpm; (initial 0.5 Nm, 1 second sudden change to 2 Nm)

[0087] Figure 6 This is a current waveform diagram of the present invention at 200 rpm after adding dead time;

[0088] Figure 7It is a comparison waveform diagram of the estimated rotor position and the actual rotor position after adding the dead time at 200 rpm of the present invention;

[0089] Figure 8 This is a current waveform diagram after the dead zone is compensated at 200 rpm;

[0090] Fig. 9 It is a comparison waveform diagram of the estimated rotor position and the actual rotor position after the dead zone is compensated at 200 rpm according to the present invention. DETAILED DESCRIPTION

[0091] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar originals or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0092] The present invention is based on the permanent magnet synchronous motor dead zone compensation method of the nonlinear flux observer, and its principle block diagram is as follows: Figure 1 As shown in the figure, this method builds a speed loop based on a nonlinear flux observer to realize a position sensorless closed-loop structure of a permanent magnet synchronous motor. The structure of the nonlinear flux observer is shown in Figure 2 Considering the influence of dead time on position sensorless control, a permanent magnet synchronous motor dead time compensation method based on nonlinear flux observer is designed. The detailed calculation principle of dead time compensation is shown in Figure 3 As shown; follow the steps below to implement:

[0093] Step 1, measure the motor induced current in the ABC coordinate system, and obtain the αβ axis current by transformation; specifically:

[0094] Step 1.1, the three-phase induced current i of the permanent magnet synchronous motor a 、i b 、i c Sampling is performed and Clarke transformation is performed to obtain the α-axis current i α and the β-axis current i β ; Then perform Park transformation on it to obtain the d-axis current i d and q-axis current i q , for the d-axis current i d and q-axis current iq Perform PI adjustment to obtain the d-axis voltage command value u d and q-axis voltage command value u q , and then perform inverse Park transformation to obtain the α-axis voltage command value u α and β-axis voltage command value u β .

[0095] Step 2: Use the nonlinear flux observer in the αβ coordinate system as the position observation model to obtain the actual rotor position estimate, thereby forming a speed loop and realizing position sensorless control of the permanent magnet synchronous motor, such as Figure 2 As shown; specifically:

[0096] Step 2.1, establish a mathematical model of the surface mounted permanent magnet synchronous motor in the αβ coordinate system, as shown in formula (1);

[0097]

[0098] Among them, L and R s are the stator inductance and stator resistance, ω and θ respectively r are the motor angular velocity and rotor position angle, ψ m is the permanent magnet flux, T e is the electromagnetic torque, and P is the number of motor poles.

[0099] Step 2.2, define the state variable x and output y, as shown in equation (2) and equation (3);

[0100]

[0101] By taking the derivative of formula (2), we can get the relationship between formula (2) and formula (3), as shown in formula (4);

[0102]

[0103] Step 2.3, define the vector function η(x), as shown in formula (5);

[0104]

[0105] Combining formula (3), the norm of η(x) is shown in formula (6);

[0106]

[0107] Step 2.4, combining equation (4), equation (5), and equation (6), construct a nonlinear flux observer model, as shown in equation (7);

[0108]

[0109] in, and are the state variable and the derivative of the state variable of the nonlinear flux observer, γ is the observer gain and γ>0;

[0110] Step 2.5, transform equation (3) to obtain equation (8);

[0111]

[0112] Therefore, the sine and cosine components of the estimated rotor position calculated by the observer are obtained as shown in equation (9);

[0113]

[0114] In the formula, To estimate the rotor position.

[0115] Step 2.6, normalize the sine and cosine components containing the estimated rotor position, and calculate through the phase-locked loop to obtain the estimated rotor position and estimated speed This forms a speed loop.

[0116] Step 3: construct a q-axis voltage disturbance observer by measuring the phase voltage output by the inverter; specifically:

[0117] Step 3.1, establish the motor voltage equation in the dq coordinate system, as shown in equation (10);

[0118]

[0119] Among them, u dd =-ωLi q ,u qd =ω(Li d +K E ), K E is the back electromotive force constant.

[0120] When dead zone compensation is not added, the command voltage u d and u q There will be a disturbance voltage in, as shown in formula (11);

[0121]

[0122] After dead zone compensation, equation (11) will change to equation (12);

[0123]

[0124] in, are the d-axis and q-axis disturbance voltages respectively, They are the d-axis and q-axis dead zone compensation voltages respectively.

[0125] Step 3.2, since the q-axis disturbance voltage changes very little and can be ignored, its derivative is always zero, as shown in equation (13);

[0126]

[0127] Therefore, the state equation of the permanent magnet synchronous motor after adding the disturbance voltage is And the output equation y1 is shown in equation (14);

[0128]

[0129] Step 3.3, construct the q-axis disturbance observer, as shown in formula (15);

[0130]

[0131] in, G2 = -Lγ1γ2, γ1 and γ2 are the observer poles.

[0132] Step 4: Use the output of the q-axis disturbance observer as the input of the dead time calculation module to obtain the dead time estimation value; specifically:

[0133] Step 4.1, to compensate for the dead zone, in the ABC coordinate system, the dead zone compensation voltage is added to the command voltage of the three phases ABC, where the dead zone compensation voltage of phase a is shown in formula (16);

[0134]

[0135] In the formula, is the dead zone compensation voltage of phase A, T c is the dead time, T s is the sampling cycle time, U dc Bus voltage.

[0136] Step 4.2, define the transformation matrix from the ABC coordinate system to the rotation coordinate system as shown in formula (17);

[0137]

[0138] Since the q-axis dead zone compensation voltage has periodic fluctuations, the q-axis maximum dead zone compensation voltage From equation (16) and equation (17), we can get:

[0139]

[0140] Its average It is obtained by integration, as shown in formula (19);

[0141]

[0142] The average value is used instead of the maximum value, as shown in formula (20);

[0143]

[0144] Step 4.3, transform equation (20) to obtain the dead time T c , as shown in formula (21);

[0145]

[0146] Step 5, according to the dead time estimation value, calculate and obtain the dead time compensation voltage, compensate the inverter output phase voltage, and realize the permanent magnet synchronous motor position sensorless dead time compensation based on the nonlinear flux observer. Specifically:

[0147] Step 5.1, let the output of the q-axis disturbance observer in step 3 be Equal to the q-axis average dead zone compensation voltage in step 4 Get estimated dead time As shown in formula (22);

[0148]

[0149] Step 5.2, substitute equation (22) into equation (16) to obtain the estimated dead zone compensation voltage of phase A, as shown in equation (22-1);

[0150]

[0151] Similarly, the estimated dead zone compensation voltage of phases BC is shown in equations (23) and (24);

[0152]

[0153] In step 5.3, the estimated dead zone compensation voltage of phases ABC is added to the three-phase voltage output by the inverter to achieve dead zone compensation.

[0154] When the permanent magnet synchronous motor runs in the high-speed zone and the inverter dead time is small, the position sensorless drive system is relatively less affected by the inverter dead time, while when the motor runs in the low-speed zone, the dead time will seriously affect the positionless control performance. In order to improve the sensorless control performance of the permanent magnet synchronous motor as an aircraft-borne pump load, the present invention proposes a permanent magnet synchronous motor dead zone compensation method based on a nonlinear flux observer for the sensorless control of the permanent magnet synchronous motor, so as to improve the control performance of the motor after a sudden load change during high-speed operation and the positionless control performance during low-speed operation.

[0155] The overall control structure of the present invention is as follows Figure 1As shown, the estimated speed and the estimated rotor position are solved by the nonlinear flux observer to form a position sensorless control closed-loop structure. By correcting the command voltage, the dead zone compensation effect is achieved. Figure 4 and Figure 5 The figure is the speed waveform diagram when the method is used and not used when the speed is given to be 8000rpm. Both figures have an initial load of 0.5Nm, and the load suddenly changes to 2Nm at 1s. It can be clearly seen from the figure that after compensating for the dead zone, the time required for the speed fluctuation caused by the load mutation to recover to the steady-state value is significantly reduced; in addition, compared with the waveform without dead zone compensation, the waveform fluctuation of the estimated speed after dead zone compensation is also improved, which is closer to the actual speed. Figures 6 to 9 Given a speed of 200 rpm, the load increases with time and reaches a maximum of 2.5 Nm at 0.35 s. From the comparison in the figure, it can be seen that after using this method, the actual rotor position waveform is better than when it is not used, which is reflected in the fact that the actual rotor position curve is closer to a straight line. However, there is a certain delay between the estimated rotor position and the actual rotor position in the figure. This is because there is a calculation delay, which can be eliminated by adding delay compensation.

[0156] It is understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of ordinary technicians in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and unless defined as here, will not be interpreted with idealized or overly formal meanings. The specific implementation methods described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Within the spirit and principle of the present invention, any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment of equivalent changes for application in other fields, but any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution content of the present invention, any modification, equivalent replacement, improvement, etc., made according to the technical essence of the present invention, should be included in the protection scope of the present invention.

Claims

1. A permanent magnet synchronous motor dead zone compensation method based on a nonlinear flux observer, characterized in that: Follow the steps below to implement it: Step 1, measure the motor induced current in the ABC coordinate system, and obtain the αβ axis current through Clark transformation; Step 2, using the nonlinear flux observer in the αβ coordinate system as the position observation model to obtain the actual rotor position estimation value, forming a speed loop, and realizing position sensorless control of the permanent magnet synchronous motor; Step 3, constructing a q-axis voltage disturbance observer by measuring the phase voltage output by the inverter; Step 4, using the output of the q-axis disturbance observer as the input of the dead time calculation module to obtain the dead time estimation value; Step 5: Calculate and obtain the dead time compensation voltage according to the dead time estimation value, and compensate the inverter output phase voltage.

2. The method according to claim 1, characterized in that Step 1 is as follows: Step 1.1, the three-phase induced current i of the permanent magnet synchronous motor a 、i b 、i c Sampling is performed and Clarke transformation is performed to obtain the α-axis current i α and the β-axis current i β ; Then perform Park transformation on it to obtain the d-axis current i d and q-axis current i q , for the d-axis current i d and q-axis current i q Perform PI adjustment to obtain the d-axis voltage command value u d and q-axis voltage command value u q , and then perform inverse Park transformation to obtain the α-axis voltage command value u α and β-axis voltage command value u β .

3. The method according to claim 1, characterized in that Step 2 is as follows: Step 2.1, establish a mathematical model of the surface mounted permanent magnet synchronous motor in the αβ coordinate system, as shown in formula (1); Among them, L and R s are the stator inductance and stator resistance, ω and θ respectively r are the motor angular velocity and rotor position angle, ψ m is the permanent magnet flux, T e is the electromagnetic torque, P is the number of motor poles; Step 2.2, define the state variable x and output y, as shown in equation (2) and equation (3); By taking the derivative of formula (2), we can get the relationship between formula (2) and formula (3), as shown in formula (4); Step 2.3, define the vector function η(x), as shown in formula (5); Combining formula (3), the norm of η(x) is shown in formula (6); Step 2.4, combining equation (4), equation (5), and equation (6), construct a nonlinear flux observer model, as shown in equation (7); in, and are the state variable and the derivative of the state variable of the nonlinear flux observer, γ is the observer gain and γ>0; Step 2.5, transform equation (3) to obtain equation (8); The sine and cosine components of the estimated rotor position calculated by the observer are obtained, as shown in equation (9); In the formula, To estimate the rotor position; Step 2.6, normalize the sine and cosine components containing the estimated rotor position, and calculate through the phase-locked loop to obtain the estimated rotor position and estimated speed This forms a speed loop.

4. The method according to claim 1, characterized in that Step 3 is as follows: Step 3.1, establish the motor voltage equation in the dq coordinate system, as shown in equation (10); Among them, u dd =-ωLi q ,u qd =ω(Li d +K E ), K E is the back electromotive force constant; When dead zone compensation is not added, the command voltage u d and u q There will be a disturbance voltage in, as shown in formula (11); After dead zone compensation, equation (11) will change to equation (12); in, are the d-axis and q-axis disturbance voltages respectively, They are the d-axis and q-axis dead zone compensation voltages respectively; Step 3.2, since the q-axis disturbance voltage changes very little and can be ignored, its derivative is always zero, as shown in equation (13); Therefore, the state equation of the permanent magnet synchronous motor after adding the disturbance voltage is And the output equation y1 is shown in equation (14); Step 3.3, construct the q-axis disturbance observer, as shown in formula (15); in, G2 = -Lγ1γ2, γ1 and γ2 are the observer poles.

5. The method according to claim 1, characterized in that Step 4 is as follows: Step 4.1, to compensate for the dead zone, in the ABC coordinate system, the dead zone compensation voltage is added to the command voltage of the three phases ABC, where the dead zone compensation voltage of phase A is shown in formula (16); In the formula, is the dead zone compensation voltage of phase A, T c is the dead time, T s is the sampling cycle time, U dc Bus voltage; Step 4.2, define the transformation matrix from the ABC coordinate system to the rotation coordinate system as shown in formula (17); Since the q-axis dead zone compensation voltage has periodic fluctuations, the q-axis maximum dead zone compensation voltage From equation (16) and equation (17), we can get: Its average It is obtained by integration, as shown in formula (19); The average value is used instead of the maximum value, as shown in formula (20); Step 4.3, transform equation (20) to obtain the dead time T c , as shown in formula (21); 6. The method according to claim 1, characterized in that Step 5 is as follows: Step 5.1, let the output of the q-axis disturbance observer in step 3 be Equal to the q-axis average dead zone compensation voltage in step 4 Get estimated dead time As shown in formula (22); Step 5.2, substitute equation (22) into equation (16) to obtain the estimated dead zone compensation voltage of phase A, as shown in equation (22-1); Similarly, the estimated dead zone compensation voltage of phases BC is shown in equations (23) and (24); In step 5.3, the estimated dead zone compensation voltage of phases ABC is added to the three-phase voltage output by the inverter to achieve dead zone compensation.

7. The method according to claim 1, characterized in that Before step 1, the motor control system should meet the sampling functions of at least two-phase current and bus voltage.

8. The method according to claim 1, characterized in that After completing step 5, the feasibility of the method is verified by simulation modeling or experiments, and the experimental verification method includes high-speed working conditions and low-speed working conditions.

9. The method according to claim 8, characterized in that The above-mentioned high-speed working condition verification method is specifically as follows: when the given speed is 8000rpm, when using this method, the initial load is 0.5Nm, and the load suddenly changes to 2Nm at 1s; after compensating for the dead zone, the time required for the speed fluctuation caused by the load mutation to recover to the steady-state value is significantly reduced; in addition, compared with the waveform without dead zone compensation, the waveform fluctuation of the estimated speed after dead zone compensation is also improved, which is closer to the actual speed.

10. The method according to claim 9, characterized in that The above-mentioned low-speed working condition verification method is specifically as follows: given a speed of 200 rpm, the load increases with time and reaches a maximum at 0.35 s, with a maximum of 2.5 Nm.

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