Permanent magnet synchronous motor sensorless system MTPA control method based on double-shaft injection

Abstract

The invention discloses a permanent magnet synchronous motor sensorless system MTPA control method based on double-shaft injection, and belongs to the technical field of permanent magnet synchronous motor MTPA control. The method aims at solving the problem that in sensorless control, the optimal current vector angle tracking precision of MTPA control is reduced under the influence of position observation errors, motor saturation nonlinearity and a cross coupling effect. Comprising the following steps: injecting a high-frequency voltage signal into an observation shafting, obtaining a rotor position tracking error signal, and obtaining a rotor position observation signal and a rotating speed observation signal; introducing a current vector compensation angle on the basis of the rotor position observation signal to obtain a compensated rotor position signal, and establishing an MTPA shaft system; an auxiliary high-frequency voltage signal is injected into an MTPA shaft system; and constructing an MTPA shafting motor torque equation considering the position observation error and the cross coupling effect, constructing an MTPA shafting efficiency optimization operation control criterion, and adaptively calculating a current vector compensation angle. The method is used for motor sensorless system control.

Description

Technical Field

[0001] The invention relates to a permanent magnet synchronous motor sensorless system MTPA control method based on dual-axis injection, belonging to the technical field of permanent magnet synchronous motor MTPA control. Background Art

[0002] Permanent magnet synchronous motors have become the key to improving the energy efficiency of motor drive systems due to their advantages such as high efficiency and high power density. They are currently widely used in industrial manufacturing, smart home and other fields. In order to reduce system cost and volume, improve system reliability in harsh environments and broaden its application scope, position sensorless control technology has received widespread attention. At the same time, the maximum torque current ratio control (MTPA) strategy has become an important way to optimize motor efficiency by optimizing the current distribution of the motor to minimize the motor current under a given torque demand.

[0003] MTPA control mainly includes analytical method, table lookup method, search method and signal injection method. However, while reducing the system size and cost, the position sensorless control technology also brings greater challenges to the accuracy of MTPA control. Due to the existence of saturation nonlinearity and cross-coupling effects, the motor parameters of permanent magnet synchronous motors will change with the change of operating conditions. The mismatch between the actual motor parameters and the control parameters will cause observation errors in the observed position of position sensorless control, affecting the control performance of the system. At the same time, the implementation of MTPA control depends on accurate motor parameters, and the existence of motor parameter uncertainty and position observation error will reduce the tracking accuracy of the optimal current vector angle of traditional MTPA control, and it is impossible to achieve the ideal maximum torque current ratio control. Therefore, studying the current vector angle tracking accuracy improvement strategy when the position observation error exists and the parameters are uncertain is of great significance to the realization of high-performance and high-efficiency sensorless systems. Summary of the invention

[0004] Aiming at the problem that the optimal current vector angle tracking accuracy of MTPA control is reduced under the influence of position observation error and the motor's own saturation nonlinearity and cross-coupling effect in position sensorless control, the present invention provides a MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection.

[0005] The present invention provides a sensorless MTPA control method for a permanent magnet synchronous motor based on dual-axis injection, comprising:

[0006] Injecting a high-frequency voltage signal into the observation shaft system, extracting the high-frequency response current of the observation shaft system, and obtaining the high-frequency response current amplitude of the observation shaft system, and constructing a rotor position tracking error signal based on the high-frequency response current amplitude; and calculating the rotor position observation signal and the speed observation signal from the rotor position tracking error signal;

[0007] A current vector compensation angle is introduced on the basis of the rotor position observation signal to obtain a compensated rotor position signal, and an MTPA shaft system is established as a new vector control shaft system based on the compensated rotor position signal;

[0008] Inject an auxiliary high-frequency voltage signal into the MTPA shaft system to extract the high-frequency response current amplitude of the MTPA shaft system; construct the MTPA shaft system motor torque equation taking into account the position observation error and cross-coupling effect based on the dq shaft system motor torque equation, and construct the MTPA shaft system efficiency optimization operation control criterion by combining the high-frequency response current amplitude and speed observation signal of the MTPA shaft system; adaptively calculate the current vector compensation angle based on the MTPA shaft system efficiency optimization operation control criterion, so that the MTPA shaft system finally converges to the shaft system with the optimal current vector angle, and realizes MTPA control;

[0009] The current vector compensation angle is set to a non-zero initial value.

[0010] According to the MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection of the present invention, the high-frequency voltage signal injected into the observation shaft system is a high-frequency sinusoidal voltage signal:

[0011]

[0012] In the formula To observe the high-frequency sinusoidal voltage signal of the d-axis of the shaft system, To observe the high-frequency sinusoidal voltage signal of the q-axis of the shaft system, U h To observe the amplitude of the high-frequency sinusoidal voltage signal of the shaft system, ω h is the frequency of the observed shaft high-frequency sinusoidal voltage signal; t is the time;

[0013] The high-frequency response current of the observed shaft system is extracted as:

[0014]

[0015] In the formula is the d-axis high-frequency response current of the observed axis system, is the q-axis high-frequency response current of the observed axis system, L d is the d-axis self-inductance of the dq axis system, L q is the q-axis self-inductance of the dq-axis system, L dq is the mutual inductance caused by the cross-coupling effect of the dq axis system, L 0 is the mean inductance, L 1 is the differential inductance, L 0 =(L d +L q ) / 2,L 1 =(L d -L q ) / 2; is the rotor position observation error, θe is the actual rotor position signal, is the rotor position observation signal,

[0016] According to the MTPA control method of the permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the high-frequency response current amplitude of the observed shaft system is:

[0017]

[0018] In the formula is the d-axis high-frequency response current amplitude of the observed shaft system, To observe the q-axis high-frequency response current amplitude of the shaft system, LPF represents low-pass filter;

[0019] The rotor position tracking error signal is obtained by normalizing the high-frequency response current amplitude of the observed shaft system:

[0020]

[0021] Where ε is the rotor position tracking error signal, θ zm is the position observation deviation caused by the cross-coupling effect:

[0022]

[0023] The rotor position tracking error signal ε is obtained by the position and speed estimator to obtain the rotor position observation signal and speed observation signal

[0024]

[0025] According to the MTPA control method of the permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the method for obtaining the MTPA shaft system motor torque equation is:

[0026] The relationship between the inductance and permanent magnet flux between the dq shaft system and the MTPA shaft system is:

[0027]

[0028] In the formula is the d-axis self-inductance of the MTPA shaft system, is the q-axis self-inductance of the MTPA shaft system, is the mutual inductance of the MTPA shaft system, J is an orthogonal matrix, J = [0-1; 1 0]; is the permanent magnet flux of MTPA shaft system d-axis, is the q-axis permanent magnet flux of the MTPA shaft system, ψ f is the permanent magnet flux of the dq axis system, is the difference of the rotor position signal between the dq shaft system and the MTPA shaft system;

[0029] MTPA shaft motor torque equation T e for:

[0030]

[0031] Where n p Indicates the number of motor pole pairs; is the d-axis stator current of the MTPA shaft system, is the q-axis stator current of the MTPA shaft system.

[0032] According to the MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection of the present invention, the auxiliary high-frequency voltage signal includes an auxiliary high-frequency sinusoidal voltage signal:

[0033]

[0034] In the formula The d-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, The q-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, is the auxiliary high-frequency sinusoidal voltage signal amplitude, is the frequency of the auxiliary high-frequency sinusoidal voltage signal.

[0035] According to the MTPA control method of the permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the high-frequency response current amplitude of the MTPA shaft system is:

[0036]

[0037] In the formula is the d-axis high-frequency response current amplitude of the MTPA shaft system, is the q-axis high-frequency response current amplitude of the MTPA shaft system.

[0038] According to the MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection of the present invention, the current vector compensation angle is expressed as θ cmp :

[0039]

[0040] According to the MTPA control method of the permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the current vector compensation angle θ cmp Medium Inductance Difference The calculation method is:

[0041]

[0042] According to the MTPA control method of the permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the method for constructing the MTPA shaft system efficiency optimization operation control criterion is:

[0043] Make the MTPA shaft system d-axis stator current According to the steady-state voltage equation, the q-axis permanent magnet flux of the MTPA shaft system is obtained

[0044]

[0045]

[0046] In the formula is the fundamental frequency stator voltage signal of the d-axis of the MTPA shaft system;

[0047] Combined with MTPA shaft inductance difference and MTPA shaft system q-axis permanent magnet flux The criterion for optimizing the operation control of MTPA shafting efficiency is as follows:

[0048]

[0049] In the formula is the optimal current vector angle.

[0050] According to the MTPA control method of a permanent magnet synchronous motor sensorless system based on dual-axis injection of the present invention, the MTPA shaft system efficiency optimization operation control criterion is combined with a proportional-integral regulator to adaptively calculate the current vector compensation angle.

[0051] Beneficial effects of the present invention: The method of the present invention constructs a dual-axis high-frequency signal injection mechanism for the observation axis system and the MTPA axis system, which can realize position observation and optimal current vector angle tracking respectively. By extracting the high-frequency response current of the MTPA axis system, the efficiency optimization operation criterion is constructed, and then the current vector angle error adaptive compensation adjustment mechanism is designed, so that the MTPA axis system finally converges to the optimal current vector axis system, and accurate MTPA control is achieved. The proposed method is different from the traditional MTPA control method that realizes current distribution in the dq axis system, but realizes optimal current vector tracking in the MTPA axis system, which improves the optimal current vector angle tracking accuracy of the position sensorless system when the position observation error exists, and reduces the algorithm's dependence on motor parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is an overall control block diagram of the MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection according to the present invention; is the MTPA shaft rotor position signal, ω eref is the speed given value, is the q-axis current given value of the MTPA shaft system, which is equal to the speed controller output. is the given value of MTPA shaft system d-axis current, is the q-axis fundamental frequency stator voltage of the MTPA shaft system, u α is the stator voltage of the α-axis of the stationary shaft system, u β is the stator voltage of the β-axis of the stationary shaft system, t d is the dead time, U dc is the bus voltage, i a is the stator current of phase A, i c is the C-phase stator current, i α is the stator current of the α-axis of the stationary shaft system, i β is the stator current of the β-axis of the stationary shaft system, i αf is the fundamental frequency current of the stator of the α-axis of the stationary shaft system, i βf is the fundamental frequency stator current of the β-axis of the stationary shaft system, It is the high-frequency stator current component of the α-axis of the stationary shaft system generated by the MTPA shaft system injection signal. It is the high-frequency stator current component of the β-axis of the stationary shaft system generated by the MTPA shaft system injection signal. The high-frequency stator current component of the α-axis of the stationary shaft system generated by the injection signal of the observed shaft system is The high-frequency stator current component of the β-axis of the stationary shaft system generated by the injection signal of the observed shaft system;

[0053] Figure 2 is a schematic diagram of the reference coordinate system in the method of the present invention; the α-β axis system in the figure is the stationary axis system, d e -q e The axis system is the observation axis system, the dq axis system is the rotation axis system, and the d zm -q zm The shaft system is a non-mutual inductance shaft system, d M -q M The shaft system is MTPA shaft system;

[0054] Figure 3 Schematic diagram of the control shaft system before adjustment in the method of the present invention; s is the stator current vector, β dq is the optimal current vector angle in the dq axis system;

[0055] Figure 4 is a schematic diagram of the control shaft system after adjustment in the method of the present invention;

[0056] Figure 5 This is an experimental waveform diagram when the motor is running at 100r / min and the load is continuously added and subtracted without using the compensation method of the present invention;

[0057] Figure 6It is an experimental waveform diagram of the compensation method of the present invention when the motor is running at 100r / min and the load is continuously added and subtracted;

[0058] Figure 7 It is a block diagram of the MTPA shaft system efficiency optimization operation control criterion combined with the proportional-integral regulator to adaptively calculate the current vector compensation angle. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0060] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0061] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0062] Specific implementation method 1. Combination Figures 1 to 4 As shown, the present invention provides a MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection, comprising:

[0063] Injecting a high-frequency voltage signal into the observation shaft system, extracting the high-frequency response current of the observation shaft system, and obtaining the high-frequency response current amplitude of the observation shaft system through a demodulation method, and constructing a rotor position tracking error signal based on the high-frequency response current amplitude; and calculating the rotor position observation signal and the speed observation signal from the rotor position tracking error signal;

[0064] A current vector compensation angle is introduced on the basis of the rotor position observation signal to obtain a compensated rotor position signal, and an MTPA shaft system is established as a new vector control shaft system based on the compensated rotor position signal;

[0065] Inject an auxiliary high-frequency voltage signal into the MTPA shaft system to extract the high-frequency response current amplitude of the MTPA shaft system; construct the MTPA shaft system motor torque equation taking into account the position observation error and cross-coupling effect based on the dq shaft system motor torque equation, and construct the MTPA shaft system efficiency optimization operation control criterion by combining the high-frequency response current amplitude and speed observation signal of the MTPA shaft system; adaptively calculate the current vector compensation angle based on the MTPA shaft system efficiency optimization operation control criterion, so that the MTPA shaft system finally converges to the shaft system with the optimal current vector angle, and realizes MTPA control;

[0066] The current vector compensation angle is set to a non-zero initial value.

[0067] Combination Figure 1 To further illustrate this embodiment, Figure 1 The main contents include dual closed-loop vector control, dual-axis high-frequency sinusoidal signal injection based on the observed axis system and MTPA axis system, high-frequency response current extraction, rotor position tracking error signal construction, rotor position and speed observation and optimal current vector angle tracking. The dual closed-loop vector control of the control system includes the speed outer loop and the current inner loop. The given speed and the observed speed are controlled by the speed outer loop to obtain the reference current. The reference current signal and the sampled feedback current signal are used to obtain the voltage signal required for motor control through the current inner loop, and the voltage signal is modulated through the SVPWM module. The modulated signal is sent to the inverter to realize motor control. The rotor position and speed are observed by injecting high-frequency voltage signals into the stator winding, extracting high-frequency response current to construct the position error tracking signal and realizing it through the phase-locked loop. The new vector control axis system is constructed by introducing the current vector compensation angle based on the observed position. The current vector compensation angle is adaptively adjusted by extracting the MTPA axis system efficiency optimization criterion and combining the proportional integral regulator to realize MTPA control.

[0068] Furthermore, the high-frequency voltage signal injected into the observation shaft system is a high-frequency sinusoidal voltage signal:

[0069]

[0070] In the formula To observe the high-frequency sinusoidal voltage signal of the d-axis of the shaft system, To observe the high-frequency sinusoidal voltage signal of the q-axis of the shaft system, U h To observe the amplitude of the high-frequency sinusoidal voltage signal of the shaft system, ω h is the frequency of the observed shaft high-frequency sinusoidal voltage signal; t is the time;

[0071] Further, combined with Figure 1 The stator current of the three-phase stationary shaft system of the permanent magnet synchronous motor is subjected to Clark transformation to obtain the current signal of the stationary shaft system, and then decoupled to obtain the high-frequency response current of the stationary shaft system, and the high-frequency response current of the observed shaft system is obtained by Park transformation:

[0072]

[0073] In the formula is the d-axis high-frequency response current of the observed axis system, is the q-axis high-frequency response current of the observed axis system, L d is the d-axis self-inductance of the dq axis system, L q is the q-axis self-inductance of the dq-axis system, L dq is the mutual inductance caused by the cross-coupling effect of the dq axis system, L 0 is the mean inductance, L1 is the differential inductance, L 0 =(L d +L q ) / 2,L 1 =(L d -L q ) / 2; is the rotor position observation error, θ e is the actual rotor position signal, is the rotor position observation signal,

[0074] Furthermore, the high-frequency response current amplitude of the observed shaft system is:

[0075]

[0076] In the formula is the d-axis high-frequency response current amplitude of the observed shaft system, To observe the q-axis high-frequency response current amplitude of the shaft system, LPF represents low-pass filter;

[0077] The high-frequency response current amplitude of the observed shaft system containing the rotor position information is normalized to obtain the rotor position tracking error signal:

[0078]

[0079] Where ε is the rotor position tracking error signal, θ zm is the position observation deviation caused by the cross-coupling effect:

[0080]

[0081] The rotor position tracking error signal ε is obtained by the position and speed estimator (phase-locked loop) to obtain the rotor position observation signal and speed observation signal

[0082] According to the basic dq axis motor torque equation, the observation axis motor torque equation considering the position observation error and cross-coupling effect is constructed, and the corresponding efficiency optimization operation criterion is established; the relationship between the inductance and permanent magnet flux between the dq axis and the observation axis is:

[0083]

[0084] In the formula and is the dq axis self-inductance of the observed axis system, To observe the mutual inductance of the shaft system; and is the dq-axis permanent magnet flux of the observed axis system; ψ fis the magnetic flux of the permanent magnet in the dq axis system; J is an orthogonal matrix, which can be expressed as J = [0 -1; 1 0].

[0085] The observed shaft motor torque equation is:

[0086]

[0087] and They are the observed shaft stator currents respectively.

[0088] The control criterion for optimizing the operation of the observed shafting efficiency is:

[0089]

[0090] Furthermore, the method for obtaining the MTPA shaft motor torque equation is:

[0091] The relationship between the inductance and permanent magnet flux between the dq shaft system and the MTPA shaft system is:

[0092]

[0093] In the formula is the d-axis self-inductance of the MTPA shaft system, is the q-axis self-inductance of the MTPA shaft system, is the mutual inductance of the MTPA shaft system, J is an orthogonal matrix, J = [0-1; 1 0]; is the permanent magnet flux of MTPA shaft system d-axis, is the q-axis permanent magnet flux of the MTPA shaft system, ψ f is the permanent magnet flux of the dq axis system, is the difference of the rotor position signal between the dq shaft system and the MTPA shaft system;

[0094] MTPA shaft motor torque equation T e for:

[0095]

[0096] Where n p Indicates the number of motor pole pairs; is the d-axis stator current of the MTPA shaft system, is the q-axis stator current of the MTPA shaft system.

[0097] Further, combined with Figure 2 As described above, a current vector compensation angle is introduced based on the estimated rotor position and the MTPA axis system is established as a new vector control axis system.

[0098] In this embodiment, the auxiliary high-frequency voltage signal injected into the MTPA shaft system includes an auxiliary high-frequency sinusoidal voltage signal:

[0099]

[0100] In the formula The d-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, The q-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, is the auxiliary high-frequency sinusoidal voltage signal amplitude, is the frequency of the auxiliary high-frequency sinusoidal voltage signal.

[0101] The high-frequency response current amplitude of the MTPA shaft system is:

[0102]

[0103] In the formula is the d-axis high-frequency response current amplitude of the MTPA shaft system, is the q-axis high-frequency response current amplitude of the MTPA shaft system.

[0104] Furthermore, the current vector compensation angle is expressed as θ cmp :

[0105]

[0106] Current vector compensation angle θ cmp Medium Inductance Difference The calculation method is:

[0107]

[0108] Finally, the method for constructing the criterion for optimizing the operation control of the MTPA shafting efficiency is as follows:

[0109] Make the MTPA shaft system d-axis stator current According to the steady-state voltage equation, the q-axis permanent magnet flux of the MTPA shaft system is obtained

[0110]

[0111]

[0112] In the formula is the fundamental frequency stator voltage signal of the d-axis of the MTPA shaft system;

[0113] Combined with MTPA shaft inductance difference and MTPA shaft system q-axis permanent magnet flux The criterion for optimizing the operation control of MTPA shafting efficiency is as follows:

[0114]

[0115] In the formula is the optimal current vector angle.

[0116] As an example, combining Figure 7 As shown in Figure 1, the MTPA shaft system efficiency optimization operation control criterion is combined with the proportional integral regulator to adaptively calculate the current vector compensation angle. p_M represents the proportionality coefficient, k i_M represents the integral coefficient, and 1 / s represents the integral operation.

[0117] Combination Figure 3 and Figure 4 As shown in FIG. 1 , through the adaptive adjustment of the current vector compensation angle, the MTPA axis system finally coincides with the axis system where the optimal current vector angle is located, thus realizing MTPA control when the position observation error exists.

[0118] Embodiment: In order to further verify the beneficial effects of the present invention, a specific embodiment is described below:

[0119] The test was conducted on a permanent magnet synchronous motor pair test platform. The 2.2kW permanent magnet synchronous motor was coaxially connected to the induction motor, and the induction motor provided the load torque. The main parameters of the permanent magnet synchronous motor used were: rated voltage 380V, rated current 4.4A, rated torque 14N·m, rated speed 1500r / min, d-axis inductance 22mH, q-axis inductance 52mH, motor pole pair number 3, rotor flux 0.46Wb, and motor stator resistance 1.8Ω.

[0120] Figure 5 and Figure 6 The figure shows the experimental waveform of the continuous addition and subtraction of the load when the motor is running at 100r / min. It can be seen that when the method of the present invention is not used, the MTPA angle error is -2.8°, -4.3° and -6.8° under 33%, 66% and 100% rated load conditions respectively. After the method of the present invention is adopted, during the continuous load change process, the MTPA angle error always converges to around 1.4°, and the MTPA compensation angle is 4.3°, 7.7° and 10.8° respectively. It can be seen from the experimental results that under different load conditions, the method of the present invention can obtain the optimal current vector angle when the position error exists.

[0121] Finally, it should be noted that although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A sensorless MTPA control method for a permanent magnet synchronous motor based on dual-axis injection, characterized in that: include: Injecting a high-frequency voltage signal into the observation shaft system, extracting the high-frequency response current of the observation shaft system, and obtaining the high-frequency response current amplitude of the observation shaft system, and constructing a rotor position tracking error signal based on the high-frequency response current amplitude; The rotor position observation signal and the speed observation signal are obtained by calculating the rotor position tracking error signal; A current vector compensation angle is introduced on the basis of the rotor position observation signal to obtain a compensated rotor position signal, and an MTPA shaft system is established as a new vector control shaft system based on the compensated rotor position signal; Inject an auxiliary high-frequency voltage signal into the MTPA shaft system to extract the high-frequency response current amplitude of the MTPA shaft system; construct the MTPA shaft system motor torque equation taking into account the position observation error and cross-coupling effect based on the dq shaft system motor torque equation, and construct the MTPA shaft system efficiency optimization operation control criterion by combining the high-frequency response current amplitude and speed observation signal of the MTPA shaft system; adaptively calculate the current vector compensation angle based on the MTPA shaft system efficiency optimization operation control criterion, so that the MTPA shaft system finally converges to the shaft system with the optimal current vector angle, and realizes MTPA control; The current vector compensation angle is set to a non-zero initial value.

2. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 1 is characterized in that: The high-frequency voltage signal injected into the observation shaft system is a high-frequency sinusoidal voltage signal: In the formula To observe the high-frequency sinusoidal voltage signal of the d-axis of the shaft system, To observe the high-frequency sinusoidal voltage signal of the q-axis of the shaft system, U h To observe the amplitude of the high-frequency sinusoidal voltage signal of the shaft system, ω h is the frequency of the observed shaft high-frequency sinusoidal voltage signal; t is the time; The high-frequency response current of the observed shaft system is extracted as: In the formula is the d-axis high-frequency response current of the observed axis system, is the q-axis high-frequency response current of the observed axis system, L d is the d-axis self-inductance of the dq axis system, L q is the q-axis self-inductance of the dq-axis system, L dq is the mutual inductance caused by the cross-coupling effect of the dq axis system, L0 is the average inductance, L1 is the differential inductance, L0=(L d +L q ) / 2, L1=(L d -L q ) / 2; is the rotor position observation error, θ e is the actual rotor position signal, is the rotor position observation signal, 3. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 2 is characterized in that: The high-frequency response current amplitude of the observed shaft system is: In the formula is the d-axis high-frequency response current amplitude of the observed shaft system, To observe the q-axis high-frequency response current amplitude of the shaft system, LPF represents low-pass filter; The rotor position tracking error signal is obtained by normalizing the high-frequency response current amplitude of the observed shaft system: Where ε is the rotor position tracking error signal, θ zm is the position observation deviation caused by the cross-coupling effect: The rotor position tracking error signal ε is used to obtain the rotor position observation signal through the position and speed estimator. and speed observation signal 4. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 3 is characterized in that: The method to obtain the MTPA shaft motor torque equation is: The relationship between the inductance and permanent magnet flux between the dq shaft system and the MTPA shaft system is: In the formula is the d-axis self-inductance of the MTPA shaft system, is the q-axis self-inductance of the MTPA shaft system, is the mutual inductance of the MTPA shaft system, J is an orthogonal matrix, J = [0-1; 1 0]; is the permanent magnet flux of MTPA shaft system d-axis, is the q-axis permanent magnet flux of the MTPA shaft system, ψ f is the permanent magnet flux of the dq axis system, is the difference of the rotor position signal between the dq shaft system and the MTPA shaft system; MTPA shaft motor torque equation T e for: Where n p Indicates the number of motor pole pairs; is the d-axis stator current of the MTPA shaft system, is the q-axis stator current of the MTPA shaft system.

5. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 4 is characterized in that: The auxiliary high-frequency voltage signal includes an auxiliary high-frequency sinusoidal voltage signal: In the formula The d-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, The q-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, is the auxiliary high-frequency sinusoidal voltage signal amplitude, is the frequency of the auxiliary high-frequency sinusoidal voltage signal.

6. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 5 is characterized in that: The high-frequency response current amplitude of the MTPA shaft system is: In the formula is the d-axis high-frequency response current amplitude of the MTPA shaft system, is the q-axis high-frequency response current amplitude of the MTPA shaft system.

7. The MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection according to claim 6 is characterized in that: The current vector compensation angle is expressed as θ cmp :

8. The MTPA control method for a permanent magnet synchronous motor sensorless system based on dual-axis injection according to claim 7 is characterized in that: Current vector compensation angle θ cmp Medium Inductance Difference The calculation method is:

9. The MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection according to claim 8, characterized in that: The method for constructing the criterion for optimizing the operation control of the MTPA shafting efficiency is as follows: Make the MTPA shaft system d-axis stator current According to the steady-state voltage equation, the q-axis permanent magnet flux of the MTPA shaft system is obtained In the formula is the fundamental frequency stator voltage signal of the d-axis of the MTPA shaft system; Combined with MTPA shaft inductance difference and MTPA shaft system q-axis permanent magnet flux The criterion for optimizing the operation control of MTPA shafting efficiency is as follows: In the formula is the optimal current vector angle.

10. The MTPA control method for a sensorless permanent magnet synchronous motor system based on dual-axis injection according to claim 9, characterized in that: The MTPA shafting efficiency optimization operation control criterion is combined with the proportional-integral regulator to adaptively calculate the current vector compensation angle.

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