Sensorless mtpa control method for permanent magnet synchronous motor based on dual-axis injection

Abstract

A kind of permanent magnet synchronous motor sensorless system MTPA control method based on double-shaft injection belongs to permanent magnet synchronous motor MTPA control technical field.The present application is aimed at the problem of optimal current vector angle tracking precision reduction under the influence of position observation error and motor own saturation nonlinearity and cross coupling effect in position sensorless control.MTPA control includes injecting high-frequency voltage signal to observation shaft system, obtaining rotor position tracking error signal, and obtaining rotor position observation signal and speed observation signal;Rotor position signal after compensation is obtained by introducing current vector compensation angle based on rotor position observation signal, and MTPA shaft system is established;Auxiliary high-frequency voltage signal is injected in MTPA shaft system;MTPA shaft system motor torque equation considering position observation error and cross coupling effect is constructed, and MTPA shaft system efficiency optimization operation control criterion is constructed, and current vector compensation angle is adaptively calculated.The present application is used for motor sensorless system control.

Description

TECHNICAL FIELD

[0001] The application relates to a sensorless system MTPA control method based on double-axis injection of a permanent magnet synchronous motor and belongs to the technical field of MTPA control of the permanent magnet synchronous motor. BACKGROUND

[0002] The permanent magnet synchronous motor has become the key to improving the energy efficiency of a motor drive system due to high efficiency and high power density, and has been widely applied in industrial manufacturing, smart home and other fields. In order to reduce the system cost and volume, improve the reliability of the system in a harsh environment and broaden the application range, the sensorless control technology has been widely concerned. Meanwhile, the maximum torque current ratio (MTPA) strategy has become an important motor efficiency optimization method by optimizing the current distribution of the motor to minimize the motor current under a given torque demand.

[0003] The MTPA control mainly includes analytical method, lookup table method, search method and signal injection method, however, the sensorless control technology reduces the system volume and cost while also bringing greater challenges to the accuracy of the MTPA control. Due to the existence of saturation nonlinearity and cross-coupling effect, the motor parameters will change with the change of the running condition. The mismatch between the actual parameters of the motor and the control parameters will cause the observation error of the observed position of the sensorless control, and affect the control performance of the system. Meanwhile, the implementation of the MTPA control depends on the accurate motor parameters, and the existence of the motor parameter uncertainty and the position observation error will reduce the tracking accuracy of the optimal current vector angle of the traditional MTPA control, and the ideal maximum torque current ratio control cannot be realized. Therefore, it is of great significance to study the current vector angle tracking accuracy improvement strategy under the existence of the position observation error and the parameter uncertainty for realizing the high-performance and high-efficiency sensorless system. SUMMARY

[0004] In view of the problem that the optimal current vector angle tracking accuracy of the MTPA control is reduced under the influence of the position observation error and the saturation nonlinearity and cross-coupling effect of the motor in the sensorless control, the application provides a sensorless system MTPA control method based on double-axis injection of a permanent magnet synchronous motor.

[0005] The sensorless system MTPA control method based on double-axis injection of the permanent magnet synchronous motor provided by the application comprises the following steps of,

[0006] A high-frequency voltage signal is injected into an observation shaft system, a high-frequency response current of the observation shaft system is extracted, a high-frequency response current amplitude of the observation shaft system is obtained, and a rotor position tracking error signal is constructed based on the high-frequency response current amplitude; a rotor position observation signal and a speed observation signal are calculated from the rotor position tracking error signal;

[0007] The rotor position observation signal is compensated by introducing a current vector compensation angle to obtain a compensated rotor position signal, and a MTPA shaft system is established based on the compensated rotor position signal as a new vector control shaft system;

[0008] An auxiliary high-frequency voltage signal is injected into the MTPA shaft system, and a high-frequency response current amplitude of the MTPA shaft system is extracted; a MTPA shaft system motor torque equation considering position observation error and cross-coupling effect is constructed according to a motor torque equation of the dq shaft system, and a MTPA shaft system efficiency optimal operation control criterion is constructed in combination with the high-frequency response current amplitude of the MTPA shaft system and a speed observation signal; the current vector compensation angle is adaptively calculated according to the MTPA shaft system efficiency optimal operation control criterion, so that the MTPA shaft system finally converges to a shaft system where the optimal current vector angle is located, and the MTPA control is realized.

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

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

[0011]

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

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

[0014]

[0015] In the formula, is a high-frequency response current of the d-axis of the observation shaft system, is a high-frequency response current of the q-axis of the observation shaft system, L d is a d-axis self-inductance of the dq shaft system, L q is a q-axis self-inductance of the dq shaft system, L dq is a mutual inductance caused by the cross-coupling effect of the dq shaft system, L0 is an average inductance, L1 is a difference inductance, L0=(L d +L q ) / 2, L1=(L d -L q ) / 2; is a rotor position observation error, θ e is an actual rotor position signal, is a rotor position observation signal,

[0016] The sensorless system MTPA control method of the dual-axis injection-based permanent magnet synchronous motor according to the present application is characterized in that the high-frequency response current amplitude of the observed shaft system is:

[0017]

[0018] wherein is the d-axis high-frequency response current amplitude of the observed shaft system, is the q-axis high-frequency response current amplitude of the observed shaft system, and LPF represents a 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] wherein 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 input into the position and speed estimator to obtain the rotor position observation signal and the speed observation signal

[0024]

[0025] The sensorless system MTPA control method of the dual-axis injection-based permanent magnet synchronous motor according to the present application is characterized in that the method for obtaining the MTPA shaft system motor torque equation is:

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

[0027]

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

[0029] The MTPA shaft system motor torque equation Te is:

[0030]

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

[0032] According to the dual-axis injection-based sensorless system MTPA control method of the permanent magnet synchronous motor of the application, the auxiliary high-frequency voltage signal comprises an auxiliary high-frequency sinusoidal voltage signal:

[0033]

[0034] wherein is the MTPA shaft d-axis auxiliary high-frequency sinusoidal voltage signal injected, is the MTPA shaft q-axis auxiliary high-frequency sinusoidal voltage signal injected, is the auxiliary high-frequency sinusoidal voltage signal amplitude, is the auxiliary high-frequency sinusoidal voltage signal frequency.

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

[0036]

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

[0038] According to the dual-axis injection-based sensorless system MTPA control method of the permanent magnet synchronous motor of the application, the current vector compensation angle is represented as θ cmp :

[0039]

[0040] According to the dual-axis injection-based sensorless system MTPA control method of the permanent magnet synchronous motor of the application, the current vector compensation angle θ cmp is calculated by the method of:

[0041]

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

[0043] MTPA shaft d-axis stator current MTPA shaft q-axis permanent magnet flux linkage is obtained according to the steady-state voltage equation

[0044]

[0045]

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

[0047] MTPA shaft inductance difference MTPA shaft q-axis permanent magnet flux linkage The MTPA shaft efficiency optimization operation control criterion is constructed as:

[0048]

[0049] In the formula Optimal current vector angle.

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

[0051] The method constructs a double-axis high-frequency signal injection mechanism of the observation shaft and the MTPA shaft, can realize position observation and optimal current vector angle tracking respectively, constructs an efficiency optimization operation criterion by extracting the high-frequency response current of the MTPA shaft, and then designs a current vector angle error adaptive compensation adjustment mechanism, so that the MTPA shaft finally converges to the optimal current vector shaft, and accurate MTPA control is realized. BRIEF DESCRIPTION OF DRAWINGS

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

[0053] Figure 2 is the schematic diagram of the reference coordinate system in the method of the present application; in the diagram, the α-β axis system is a static axis system, the d e -q e axis system is an observation axis system, the d-q axis system is a rotating axis system, the d zm -q zm axis system is a non-interaction axis system, the d M -q M axis system is an MTPA axis system;

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

[0055] Figure 4 is the schematic diagram of the control axis system after adjustment in the method of the present application;

[0056] Figure 5 is the experimental waveform diagram of the motor running at 100 r / min with continuous load increase and decrease without compensation by the method of the present application;

[0057] Figure 6 is the experimental waveform diagram of the motor running at 100 r / min with continuous load increase and decrease with compensation by the method of the present application;

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

[0059] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0060] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0061] The present application will be further described below in combination with the drawings and specific embodiments, but is not limited to the present application.

[0062] Specific embodiment one, in combination Figures 1 to 4 As shown in the figure, the present application provides a sensorless system MTPA control method of a permanent magnet synchronous motor based on double-axis injection, comprising:

[0063] A high-frequency voltage signal is injected into the observation shaft system, the high-frequency response current of the observation shaft system is extracted, and the high-frequency response current amplitude of the observation shaft system is obtained through a demodulation method. A rotor position tracking error signal is constructed based on the high-frequency response current amplitude; the rotor position observation signal and the speed observation signal are calculated from the rotor position tracking error signal;

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

[0065] An auxiliary high-frequency voltage signal is injected into the MTPA shaft system, and the high-frequency response current amplitude of the MTPA shaft system is extracted; an MTPA shaft system motor torque equation considering position observation error and cross-coupling effect is constructed according to the dq shaft system motor torque equation, and an MTPA shaft system efficiency optimal operation control criterion is constructed in combination with the high-frequency response current amplitude of the MTPA shaft system and the speed observation signal; the current vector compensation angle is adaptively calculated according to the MTPA shaft system efficiency optimal operation control criterion, so that the MTPA shaft system finally converges to the shaft system where the optimal current vector angle is located, and the MTPA control is realized;

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

[0067] In combination Figure 1 The present embodiment is further described, Figure 1The main control system includes double closed loop vector control, double shaft system high frequency sinusoidal signal injection based on observation shaft system and MTPA shaft system, high frequency response current extraction, rotor position tracking error signal construction, rotor position and speed observation and optimal current vector angle tracking. The double closed loop vector control of the control system includes speed outer loop and 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 feedback current signal obtained by sampling are controlled by the current inner loop to obtain the voltage signal required for motor control. The modulated signal is sent to the inverter to realize motor control through the SVPWM module. The observation of rotor position and speed is realized by injecting high frequency voltage signal into the stator winding, extracting high frequency response current, constructing position error tracking signal and realizing it through phase-locked loop. The new vector control shaft system is constructed by introducing current vector compensation angle based on the observation position. The current vector compensation angle is self-adaptively adjusted by extracting MTPA shaft system efficiency optimization criterion and combining proportional integral regulator, so as to realize MTPA control.

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

[0069]

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

[0071] Further, in combination with Figure 1 the stator current of the permanent magnet synchronous motor under the three-phase static shaft system is subjected to Clark transformation to obtain the current signal under the static shaft system, then decoupling processing is carried out to obtain the high frequency response current under the static shaft system, and the high frequency response current of the observation shaft system is obtained through Park transformation:

[0072]

[0073] In the formula, is the high frequency response current of the d-axis of the observation shaft system, is the high frequency response current of the q-axis of the observation shaft system, L d is the self-inductance of the d-axis of the dq shaft system, L q is the self-inductance of the q-axis of the dq shaft system, L dq is the mutual inductance caused by the cross coupling effect of the dq shaft system, L0 is the average inductance, L1 is the difference inductance, L0=(L d +L q ) / 2, L1=(L d -L q) / 2; is the rotor position observation error, e is the rotor actual position signal, is the rotor position observation signal,

[0074] Further, the high frequency response current amplitude of the observation axis system is:

[0075]

[0076] wherein is the d-axis high frequency response current amplitude of the observation axis system, is the q-axis high frequency response current amplitude of the observation axis system, and LPF represents a low pass filter;

[0077] The rotor position tracking error signal is obtained by normalizing the high frequency response current amplitude of the observation axis system containing rotor position information:

[0078]

[0079] wherein 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 the speed observation signal

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

[0083]

[0084] wherein and is the observation axis system dq-axis self-inductance, is the observation axis system mutual inductance; and is the observation axis system dq-axis permanent magnet flux linkage; ψ f is the dq-axis system permanent magnet flux linkage; J is an orthogonal matrix, which can be expressed as J = [0 -1; 1 0].

[0085] The observation axis system motor torque equation is:

[0086]

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

[0088] The observed shaft system efficiency optimal operation control criterion is:

[0089]

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

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

[0092]

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

[0094] The MTPA shaft system motor torque equation T e is:

[0095]

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

[0097] Further, in combination with Figure 2 on the basis of the estimated rotor position, a current vector compensation angle is introduced and the MTPA shaft system is established as a new vector control shaft system.

[0098] In the 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, is the d-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, is the q-axis auxiliary high-frequency sinusoidal voltage signal injected into the MTPA shaft system, is the amplitude of the auxiliary high-frequency sinusoidal voltage signal, is the frequency of the auxiliary high-frequency sinusoidal voltage signal.

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

[0102]

[0103] where 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] Further, the current vector compensation angle is denoted as cmp :

[0105]

[0106] The current vector compensation angle cmp is calculated as

[0107] Finally, the method for constructing the efficiency optimal operation control criterion of the MTPA shaft system is

[0108]

[0109] is the d-axis stator current of the MTPA shaft system, is the q-axis permanent magnet flux linkage of the MTPA shaft system,

[0110]

[0111]

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

[0113] is the inductance difference of the MTPA shaft system, and is the q-axis permanent magnet flux linkage of the MTPA shaft system, the efficiency optimal operation control criterion of the MTPA shaft system is constructed as

[0114]

[0115] where is the optimal current vector angle.

[0116] As an example, as shown in Figure 7 , the efficiency optimal operation control criterion of the MTPA shaft system adaptively calculates the current vector compensation angle in combination with a proportional-integral regulator. In the figure, k p_M represents the proportional coefficient, k​i_M represents an integral coefficient, and 1 / s represents an integral operation.

[0117] Combining Figure 3 and Figure 4 As shown in the figure, through adaptive adjustment of the current vector compensation angle, the final MTPA axis system coincides with the axis system where the optimal current vector angle is located, and MTPA control is realized when the position observation error exists.

[0118] Embodiment: In order to further verify the beneficial effects of the present application, the following will be described with a specific embodiment:

[0119] The experiment was verified on a permanent magnet synchronous motor drag experiment platform. A 2.2kW permanent magnet synchronous motor was coaxially connected with an induction motor, and the induction motor provided a 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 As shown in the figure, when the method of the present application is not used, the MTPA angle error is-2.8°, -4.3° and-6.8° under the conditions of 33%, 66% and 100% rated load, respectively. After the method of the present application is used, the MTPA angle error converges to about 1.4° during the continuous change of the load, and the MTPA compensation angle is 4.3°, 7.7° and 10.8°, respectively. From the experimental results, it can be seen that under different load conditions, the method of the present application can obtain the optimal current vector angle when the position error exists.

[0121] Finally, it should be noted that although the present application has been described herein with reference to particular embodiments, it should be understood that these examples are merely illustrative of the principles and applications of the present application. It should therefore be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It should be understood that the features described in connection with one embodiment can be used in conjunction with other embodiments described herein. It should also be understood that features described in connection with separate embodiments can be used in other described embodiments.

Claims

1. A sensorless system MTPA control method for a permanent magnet synchronous motor based on dual-axis injection, characterized in that, The method comprises the following steps: Injecting a high-frequency voltage signal into an observation shaft system, extracting a high-frequency response current of the observation shaft system, and obtaining a 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; Calculating a rotor position observation signal and a rotor speed observation signal from the rotor position tracking error signal; Introducing a current vector compensation angle into the rotor position observation signal to obtain a compensated rotor position signal, and establishing an MTPA shaft system as a new vector control shaft system based on the compensated rotor position signal; Injecting an auxiliary high-frequency voltage signal into the MTPA shaft system, extracting a high-frequency response current amplitude of the MTPA shaft system, constructing an MTPA shaft system motor torque equation considering position observation error and cross-coupling effect according to a dq shaft system motor torque equation, constructing an MTPA shaft system efficiency optimal operation control criterion combined with the high-frequency response current amplitude of the MTPA shaft system and the rotor speed observation signal, and adaptively calculating a current vector compensation angle according to the MTPA shaft system efficiency optimal operation control criterion, so that the MTPA shaft system finally converges to an optimal current vector angle shaft system, and MTPA control is realized; The current vector compensation angle is set to a non-zero initial value; The method for constructing the MTPA shaft system efficiency optimal operation control criterion is: MTPA shaft set d-axis stator current MTPA shaft set q-axis permanent magnet flux linkage from steady state voltage equation wherein is the MTPA shafting d-axis fundamental frequency stator voltage signal; is the speed observation signal, is the MTPA shafting q-axis self-inductance, is the MTPA shafting q-axis stator current, is the auxiliary high frequency sinusoidal voltage signal amplitude, is the MTPA shafting d-axis high frequency response current amplitude, is the auxiliary high frequency sinusoidal voltage signal frequency, is the MTPA shafting q-axis high frequency response current amplitude, θ cmp is the current vector compensation angle; Combining mtpa shaft system inductance difference And mtpa shaft system q-axis permanent magnet flux linkage The construction mtpa shaft system efficiency optimization operation control criterion is: wherein is the MTPA shafting d-axis self-induction, is the optimal current vector angle, T e is the MTPA shafting motor torque equation, n p is the motor pole pair number.

2. The sensorless system MTPA control method for a two-axis injection-based permanent magnet synchronous motor according to claim 1, characterized by, The high-frequency voltage signal injected into the observation shaft system is a high-frequency sinusoidal voltage signal: wherein Ud is the observed shaft system d-axis high frequency sinusoidal voltage signal, Uq is the observed shaft system q-axis high frequency sinusoidal voltage signal, U h U is the observed shaft system high frequency sinusoidal voltage signal amplitude, ω h is the observed shaft system high frequency sinusoidal voltage signal frequency; t is time; The high-frequency response current extracted from the observation shaft system is: wherein is the d-axis high frequency response current of the shaft system, is the q-axis high frequency response current of the shaft 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 difference inductance, L0 = (L d + L q ) / 2, L1 = (L d - L q ) / 2; is the rotor position observation error, θ e is the rotor actual position signal, is the rotor position observation signal, 3. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 2, characterized by, The high-frequency response current amplitude of the observation shaft system is: In the formula is the d-axis high-frequency response current amplitude of the shaft system, and is the q-axis high-frequency response current amplitude of the shaft system, and LPF represents a low-pass filter. The rotor position tracking error signal is obtained by normalizing the high-frequency response current amplitude of the observation shaft system: where ε is the rotor position tracking error signal, θ zm Position observation bias due to cross-coupling effect: The rotor position tracking error signal ε is passed through a position speed estimator to obtain a rotor position observation signal and a speed observation signal 4. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 3, characterized by, The method for obtaining the MTPA shaft system motor torque equation is: The relationship between inductance and permanent magnet flux linkage between the dq shaft system and the MTPA shaft system is: wherein is the MTPA shafting mutual inductance, J is the orthogonal matrix, J = [0 -1 ; 1 0]; is the MTPA shafting d-axis permanent magnet flux linkage, ψ f is the dq shafting permanent magnet flux linkage, is the difference between the rotor position signals of the dq shafting and the MTPA shafting; MTPA shafting motor torque equation T e is: In the formula is the d-axis stator current for the MTPA shaft system.

5. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 4, characterized by, The auxiliary high-frequency voltage signal includes an auxiliary high-frequency sinusoidal voltage signal: wherein is a d-axis auxiliary high-frequency sinusoidal voltage signal injected to the MTPA shafting, is a q-axis auxiliary high-frequency sinusoidal voltage signal injected to the MTPA shafting.

6. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 5, characterized by, The high-frequency response current amplitude of the MTPA shaft system is:

7. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 6, characterized by, Current vector compensation angle θ cmp is:

8. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 7, characterized by, Current vector compensation angle θ cmp Inductance difference The calculation method is:

9. The sensorless system MTPA control method of a two-axis injection-based permanent magnet synchronous motor according to claim 8, characterized by, The MTPA shaft system efficiency optimal operation control criterion is combined with a proportional-integral regulator to adaptively calculate the current vector compensation angle.

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