CN104767455B - A kind of hybrid exciting synchronous motor position-sensor-free direct torque control method - Google Patents

Abstract

The invention discloses a direct torque control method for a hybrid excitation synchronous motor without a position sensor. A sliding film observer is used to estimate the rotational speed and initial position of the hybrid excitation synchronous motor. The overall control idea is based on the direct torque control method. Judging the motor operating area according to the speed, the motor runs in the low speed area, and adopts i _d = 0 control. When the load torque is less than or equal to the rated torque, there is no need for magnetization control; when the load torque is greater than the rated torque, the magnetization control is performed . The motor runs in the high-speed area and adopts field-weakening control. First, keep _id = 0, and use the excitation current if to carry out field-weakening _; when the field current if reaches the rated value, use the _d -axis current _id to carry out field-weakening. The position sensorless direct torque control of the hybrid excitation synchronous motor reduces the cost and improves the reliability and torque quick response capability of the drive system.

Description

A Sensorless Direct Torque Control Method for Hybrid Excitation Synchronous Motor

technical field

The invention belongs to the technical field of electric transmission, and relates to a direct torque strategy without a position sensor, in particular to a control method for a hybrid excitation synchronous motor.

Background technique

Hybrid excitation synchronous motor is a kind of wide speed regulation motor developed on the basis of permanent magnet synchronous motor and electric excitation synchronous motor. Its main purpose is to solve the problem that the air gap magnetic field of permanent magnet synchronous motor is difficult to adjust. The hybrid excitation synchronous motor has two excitation sources, one is permanent magnet and the other is electric excitation. The magnetic potential generated by the permanent magnet is the main magnetic potential, and the magnetic potential generated by the excitation winding is the auxiliary magnetic potential. This motor combines the advantages of permanent magnet synchronous and electric excitation synchronous motors. The two excitation sources interact in the air gap of the motor to generate the main magnetic flux. When the electric excitation coil is fed with positive excitation current, positive electromagnetic rotation is generated. The torque increases the motor torque; on the contrary, when the electric excitation coil passes the reverse excitation current, a reverse magnetic field is generated to weaken the air gap magnetic field to achieve the purpose of weakening the magnetic field and increasing the speed, thus widening the speed regulation range of the motor.

At present, there are few studies on the control method and drive system of hybrid excitation synchronous motors at home and abroad, which basically focus on vector control, and it is controlled by sensors. Based on vector control, it can be classified into _three categories. is the field weakening strategy, and the last one is the efficiency optimal strategy. The advantage of the above control strategy is continuous control, which is relatively smooth; the disadvantage is that the torque dynamic response is not fast enough, and the rotation coordinate transformation is required, which is more complicated. Due to the presence of sensors, the control system is expensive, prone to failure, and low in reliability.

Contents of the invention

Technical problem: The present invention provides a sensorless direct torque control method with faster torque dynamic response, high system reliability and low cost.

Technical solution: The position sensorless direct torque control method of the hybrid excitation synchronous motor of the present invention comprises the following steps:

(1) Three Hall current sensors and two voltage sensors respectively collect phase current _ia , _ib and excitation current if, bus voltage U _DC and excitation voltage U _f from the main circuit of the motor, and _pass the collected signals through voltage Follow, filter, bias and overvoltage protection signals are conditioned and sent to the controller;

(2) A/D conversion is performed on the phase currents i _a and i _b sent to the controller, and the α-axis current i in the two-phase stationary coordinate system is obtained through the 3/2 transformation from the three-phase coordinate system to the two-phase stationary coordinate system _α and β axis current i _β ; using the U _DC sent to the controller and the switch states S _a , S _b , S _c , determine the α axis voltage u _α and β axis voltage u _β in the two-phase stationary coordinate system according to the following formula :

Among them, S _a , S _b , and S _c are the switching states of the upper and lower switching tubes of the inverter three-phase bridge arms a, b, and c, respectively. When the upper bridge arm is turned on, the value is 1; when the lower bridge arm is turned on, the value 0;

(3) Using the i _α , i _β , u _α , u _β obtained in step (2), calculate the actual electromagnetic torque estimated value T _e , the actual stator flux linkage estimated value ψ _s , and the stator flux linkage working value respectively according to the following formulas: Sector estimate θ _i :

Among them, ψ _α and ψ _β are the stator α-axis flux linkage and β-axis flux linkage in the two-phase stationary coordinate system, respectively, R _s is the armature winding resistance, and p is the number of pole pairs of the motor;

According to the following formulas, the estimated value of the actual speed n and the estimated value of the rotor position angle θ _e are respectively calculated:

where _K1 is the fixed observation gain, is the observation error current of the stator α-axis, is the stator β-axis observation error current, are the observed currents on the α-axis and β-axis respectively, sign() is the sign function, e _α and e _β are the counter electromotive forces of the α-axis and β-axis respectively, and ω _e is the electrical angular velocity;

(4) Subtract the speed n estimated in step 3) from the given speed n _ref , input the obtained speed deviation Δn into the speed regulator to obtain the electromagnetic torque reference value T _eref , and convert the electromagnetic torque reference value T _eref and the estimated speed n are sent to the current distributor to determine whether the actual speed is less than the rated speed, if so, the motor runs in the low speed zone, and enters step 5); otherwise, the motor runs in the high speed zone, and enters step 6);

(5) Determine whether the load torque satisfies T _L ≤ T _N , determine the stator flux reference value ψ _sref and the electromagnetic torque reference value T _eref , and then enter step (7), where T _L is the load torque and T _N is the rated Torque, as follows;

When T _{L ≤} T _N , there is no need for magnetization control, if if = 0, use i _d = 0 control, and carry out current distribution according to the following current distribution scheme:

Then the reference value of the stator flux linkage is obtained

When T _L >T _N , the q-axis current has reached the rated value, and magnetization control is required, so i _q =i _qN , and the d-axis current i _d =0 is used for control, and the current distribution is performed according to the following current distribution scheme:

Then the reference value of the stator flux linkage is obtained as:

Among them, i _dref and i _qref are the d-axis and q-axis current reference values respectively, i _qN is the rated value of the q-axis current; i _fref is the excitation current reference value; L _d and L _q are the d-axis and q-axis inductances respectively, M _f is the mutual inductance between the armature and the field winding; ψ _m is the flux linkage of the permanent magnet; _{ψ d} , ψ _q are the flux linkages of the _d -axis and q-axis respectively; _sref is the stator flux reference value;

(6) First judge whether the rotational speed is less than the field-weakening base speed n _flux , if so, keep the d-axis current i _d = 0, adopt the field current i _f to weaken the field, and carry out current distribution according to the following current distribution scheme:

Reference value of stator flux linkage

If the given speed reaches the field-weakening base speed n _flux and the excitation current if reaches the rated value, continue to use the _{d-axis current i d to} weaken the field, and carry out current distribution according to the following current distribution scheme:

Reference value of stator flux linkage

Among them, I _fN is the rated value of excitation current, ω _eN is the rated electrical angular velocity;

(7) Subtract the actual stator flux estimated value ψ _s obtained in step (3) from the stator flux reference value ψ _sref to obtain the stator flux deviation Δψ _s , _and subtract the step ( 3) The actual electromagnetic torque estimated value T _e is obtained to obtain the electromagnetic torque deviation ΔT _e , and then Δψ _s is sent to the hysteresis comparator to obtain the torque control signal τ, and ΔT _e is sent to the hysteresis comparator to obtain the flux linkage control Signal φ, three control signals τ, φ, θ select the switching state through the switch table to drive the main power converter;

At the same time, the excitation current if collected in step (1) is sent to the DC excitation pulse width modulation module together with the excitation current reference value _{i fref} obtained in step (5) or (6) after signal conditioning and A/D conversion , the operation outputs 4 pulse width modulation signals to drive the excitation power converter.

In a preferred solution of the method of the present invention, the DC excitation pulse width modulation module in step 7) is a space vector pulse width modulation module.

Beneficial effects: Most of the existing hybrid excitation synchronous motor control methods are based on vector control. Although the control method is simple and convenient, the torque response is slow, and most of them adopt the position sensor strategy. Therefore, this kind of control method makes the reliability of the control system low, and the price is relatively high. The present invention uses the positionless direct torque control method from step 3) to step 6), so that the hybrid excitation synchronous motor runs in the entire operating region, and has high reliability and torque dynamic response. Therefore, the present invention has the following advantages relative to the existing control method:

(1) This method adopts direct torque control, which makes the torque dynamic response faster;

(2) Compared with position sensor control, the present invention adopts position sensorless control, improves system reliability, and greatly reduces cost;

(3) Compared with vector control, this control method makes the hybrid excitation motor obtain a wide application prospect in electric vehicles.

Description of drawings

Fig. 1 is a logic flow diagram of the inventive method;

Fig. 2 is a system block diagram of the inventive method;

Fig. 3 is a structural block diagram realizing the method of the present invention;

Fig. 4 is a judgment diagram of speed and position angle without position.

Detailed ways

The present invention will be further described below in conjunction with embodiment and accompanying drawing.

Fig. 2 is the system block diagram that realizes the position sensorless direct torque control method of hybrid excitation synchronous motor of the present invention, and this control system consists of AC power supply, rectifier, voltage stabilizing capacitor, DSP controller, main power converter, auxiliary power converter, current It is composed of a voltage sensor and a hybrid excitation synchronous motor.

The AC power supplies power to the entire system. After being rectified by the rectifier, the voltage is filtered and stabilized, and sent to the main and auxiliary power converters. The Hall voltage sensor collects the bus voltage and sends it to the controller after conditioning. The output terminals of the main and auxiliary power converters are connected to the hybrid excitation synchronous motor, and the Hall current transformer collects the phase current and excitation current, and sends them to the controller after conditioning, and sends them to the controller to calculate the rotor position angle and speed after processing. The controller outputs 10 channels of PWM signals to drive the main and excitation power converters respectively.

The position sensorless direct torque control method of the hybrid excitation synchronous motor of the present invention is shown in Figure 3, specifically comprising the following steps:

(1) Three Hall current sensors and two voltage sensors respectively collect phase current _ia , _ib and excitation current if, bus voltage U _DC and excitation voltage U _f from the main circuit of the motor, and _pass the collected signals through voltage Signals such as following, filtering, bias and overvoltage protection are conditioned and sent to the controller.

(2) A/D conversion is performed on the phase currents i _a and i _b sent to the controller, and the α-axis current i in the two-phase stationary coordinate system is obtained through the 3/2 transformation from the three-phase coordinate system to the two-phase stationary coordinate system _α and β axis current i _β ; using the U _DC sent to the controller and the switch states S _a , S _b , S _c , determine the α axis voltage u _α and β axis voltage u _β in the two-phase stationary coordinate system according to the following formula : as shown in the following formula.

Among them, S _a , S _b , and S _c are the switching states of the upper and lower switching tubes of the inverter three-phase bridge arms a, b, and c, respectively. When the upper bridge arm is turned on, the value is 1; when the lower bridge arm is turned on, the value 0; (3) Use i _α , i _β , u _α , u _β obtained in step 2) to estimate actual speed n, actual torque T _e , actual stator flux linkage ψ _s , rotor position θ _e and sector θ _i , details as follows

The voltage equation of the hybrid excitation synchronous motor in the αβ coordinate system is

Flux linkage equation

Stator flux linkage

Put formula (4) into formula (3) to get

torque equation

The actual stator flux linkage can be estimated by formula (5), the actual electromagnetic torque can be estimated by formula (6), and the working sector can be estimated by formula (7).

Among them, ψ _α and ψ _β are the stator α-axis flux linkage and β-axis flux linkage in the two-phase stationary coordinate system respectively, R _s is the _armature winding resistance, T _e is the electromagnetic torque, if is the field winding current, ω _e is the electrical angular velocity, M _f is the mutual inductance between the armature and the field winding, and ψ _m is the flux linkage of the permanent magnet.

Design a synovial film observer to estimate the rotational speed n and the rotor position angle θ _e , as shown in Fig. 4, and the details are as follows:

Establish the mathematical model of the synovium observer:

where _K1 is the fixed observation gain, are the observed currents of the α-axis and β-axis respectively, Observe the error current, sign() is a sign function.

Subtract formula (2) from formula (8) to get

When the synovium observer is stable, we can get

Among them, e _α and e _β are the back electromotive force of the α axis and the β axis respectively.

Use low-pass filter to extract continuous equivalent signal from the switching value of formula (10) thus available

From this, the estimated value of the rotor position angle θ _e can be obtained as

Thus, the speed estimation value n can be obtained as

Among them, p is the number of motor pole pairs.

(4) Subtract the speed n estimated in step 3) from the given speed n ^* , and input the obtained speed deviation Δn into the speed regulator to obtain the torque reference value Set the torque reference value to and the estimated rotational speed n are sent to the current distributor to determine whether the actual rotational speed is less than the rated rotational speed, if so, the motor operates in the low-speed area, and enter step 5), otherwise, enter step 6).

(5) The control strategy of the hybrid excitation synchronous motor in the low-speed area is analyzed below, as follows;

In the d-q coordinate system, the mathematical model of the hybrid excitation synchronous motor is shown in formula (14) to formula (16) Flux linkage equation:

Voltage equation:

Torque equation:

Among them, id and i _q are the _d -axis and q-axis currents respectively; L _d and L _q are the inductances of the d-axis and q-axis respectively; u _d and u _q are the voltages of the d-axis and q-axis respectively, and u _f is the excitation winding Voltage; R _f is the excitation winding resistance; ψ _d , ψ _q , ψ _f are respectively d-axis, q-axis and the flux linkage of the excitation winding.

When T _L ≤ T _N , there is no need for magnetization control, so if if = 0, use i _d = 0 control, combined with formula (16 ₎ , the following current distribution can be obtained:

The reference value of stator flux linkage is

Put formula (17) into formula (18) to get

When T _L > T _N , the q-axis current has reached the rated value, and magnetization control is required, so i _q = i _qN , using i _d = 0 control, combined with formula (16), the following current distribution can be obtained:

Put formula (20) into formula (18) to get

Among them, i _dref and i _qref are the d-axis and q-axis current reference values respectively, i _qN is the rated value of the q-axis current; i _fref is the excitation current reference value; T _eref is the electromagnetic torque reference value, ψ _s is the stator magnetic Chain, ψ _sref is the reference value of stator flux linkage.

After the calculation in step 5), directly enter step 7) for control.

(6) When the hybrid excitation motor enters the high-speed zone, the back EMF base value is

E _base = ω _eN ψ _m (22)

The q-axis back EMF is

E _q ＝ω _e (ψ _m +L _d i _d +M _f i _f ) (23)

Let formula (22) be equal to formula (23), we can get

First judge whether the rotational speed is less than the field-weakening base speed n _flux , if so, keep the d-axis current i _d = 0, and use the field current i _f to weaken the field, and the following current distribution can be obtained:

Put formula (25) into formula (18) to get

If the rotational speed reaches the field-weakening base speed _nflux and the excitation current reaches the rated value, the following results are obtained:

Continue to use the d-axis current i _d to weaken the field, so the following current distribution can be obtained:

Put formula (27) into formula (18) to get

Among them, I _fN is the rated value of the excitation current, ω _eN is the rated electrical angular velocity, E _base is the base value of the back EMF, and E _q is the back EMF of the q-axis.

After step 6) calculation, directly enter step 7) for control.

(7) Subtract the estimated stator flux linkage value ψ _s in step (3) from the stator flux linkage reference value ψ _sref to obtain the stator flux linkage deviation Δψ _s , and subtract step (3) from the electromagnetic torque reference value T _eref The electromagnetic torque estimation value T _e in the electromagnetic torque deviation ΔT _e is obtained, and then Δψ _s is sent to the hysteresis comparator to obtain the torque control signal τ, and ΔT _e is sent to the hysteresis comparator to obtain the flux linkage control signal φ. The three control signals τ, φ, θ are selected through the switch table shown in Table 1 to select the appropriate switch state to drive the main power converter;

Table 1 Inverter switch table

At the same time, the excitation current if collected in step (1) is sent to the DC excitation pulse width modulation module together with the excitation current reference value _{i fref} obtained in steps (5) and (6) after signal conditioning and A/D conversion. The operation outputs 4 pulse width modulation signals to drive the excitation power converter.

The foregoing embodiments are only preferred implementations of the present invention. It should be pointed out that those skilled in the art can make several improvements and equivalent replacements without departing from the principle of the present invention. Technical solutions requiring improvement and equivalent replacement all fall within the protection scope of the present invention.

Claims (2)

1. a hybrid excitation synchronous motor position sensorless direct torque control method, is characterized in that, the method comprises the following steps: (1) Three Hall current sensors and two voltage sensors respectively collect phase current _ia , _ib and excitation current if, bus voltage U _DC and excitation voltage U _f from the main circuit of the motor, and _pass the collected signals through voltage Follow, filter, bias and overvoltage protection signals are conditioned and sent to the controller; (2) A/D conversion is performed on the phase currents i _a and i _b sent to the controller, and the α-axis current i in the two-phase stationary coordinate system is obtained through the 3/2 transformation from the three-phase coordinate system to the two-phase stationary coordinate system _α and β axis current i _β ; using the U _DC sent to the controller and the switch states S _a , S _b , S _c , determine the α axis voltage u _α and β axis voltage u _β in the two-phase stationary coordinate system according to the following formula : <mrow><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>u</mi><mi>&amp;alpha;</mi></msub></mtd></mtr><mtr><mtd><msub><mi>u</mi><mi>&amp;beta;</mi></msub></mtd></mtr></mtable></mfenced><mo>=</mo><mfrac><msub><mi>U</mi><mrow><mi>D</mi><mi>C</mi></mrow></msub><mn>3</mn></mfrac><mfenced open = "[" close = "]"><mtable><mtr><mtd><mn>2</mn></mrow>mtd><mtd><mrow><mo>-</mo><mn>1</mn></mrow></mtd><mtd><mrow><mo>-</mo><mn>1</mn></mrow></mtd></mtr><mtr><mtd><mn>0</mn></mtd><mtd><msqrt><mn>3</mn></mn>msqrt></mtd><mtd><mrow><mo>-</mo><msqrt><mn>3</mn></msqrt></mrow></mtd></mtr></mtable></mfenced><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>S</mi><mi>a</mi></msub></mtd></mtr><mtr><mtd><msub><mi>S</mi><mi>b</mi></msub></mtd></mtr><mtr><mtd><msub><mi>S</mi><mi>c</mi></msub></mtd></mtr></mtable></mfenced></mrow> Among them, S _a , S _b , and S _c are the switching states of the upper and lower switching tubes of the inverter three-phase bridge arms a, b, and c, respectively. When the upper bridge arm is turned on, the value is 1; when the lower bridge arm is turned on, the value 0; (3) Using the i _α , i _β , u _α , u _β obtained in step (2), calculate the actual electromagnetic torque estimated value T _e , the actual stator flux linkage estimated value ψ _s , and the stator flux linkage working value respectively according to the following formulas: Sector estimate θ _i : <mrow><msub><mi>&amp;psi;</mi><mi>s</mi></msub><mo>=</mo><msqrt><mrow><msup><mrow><mo>(</mo><mo>&amp;Integral;</mo><mo>(</mo><msub><mi>u</mi><mi>&amp;alpha;</mi></msub><mo>-</mo><msub><mi>R</mi><mi>s</mi></msub><msub><mi>i</mi><mi>&amp;alpha;</mi></msub><mo>)</mo><mi>d</mi><mi>t</mi><mo>)</mo></mrow><mn>2</mn></msup><mo>+</mo><msup><mrow><mo>(</mo><mo>&amp;Integral;</mo><mo>(</mo><msub><mi>u</mi><mi>&amp;beta;</mi></msub><mo>-</mo><msub><mi>R</mi><mi>s</mi></msub><msub><mi>i</mi><mi>&amp;beta;</mi></msub><mo>)</mo><mi>d</mi><mi>t</mi><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt></mrow> <mrow><msub><mi>T</mi><mi>e</mi></msub><mo>=</mo><mfrac><mn>3</mn><mn>2</mn></mfrac><mi>p</mi><mrow><mo>(</mo><msub><mi>&amp;psi;</mi><mi>&amp;alpha;</mi></msub><msub><mi>i</mi><mi>&amp;beta;</mi></msub><mo>-</mo><msub><mi>&amp;psi;</mi><mi>&amp;beta;</mi></msub><msub><mi>i</mi><mi>&amp;alpha;</mi></msub><mo>)</mo></mrow></mrow> <mrow><msub><mi>&amp;theta;</mi><mi>i</mi></msub><mo>=</mo><mi>a</mi><mi>r</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>n</mi><mrow><mo>(</mo><mfrac><msub><mi>&amp;psi;</mi><mi>&amp;alpha;</mi></msub><msub><mi>&amp;psi;</mi><mi>&amp;beta;</mi></msub></mfrac><mo>)</mo></mrow></mrow> Among them, ψ _α and ψ _β are the stator α-axis flux linkage and β-axis flux linkage in the two-phase stationary coordinate system, respectively, R _s is the armature winding resistance, and p is the number of pole pairs of the motor; According to the following formulas, the estimated value of the actual speed n and the estimated value of the rotor position angle θ _e are respectively calculated: <mrow><msub><mi>&amp;theta;</mi><mi>e</mi></msub><mo>=</mo><mi>a</mi><mi>r</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>n</mi><mrow><mo>(</mo><mfrac><msub><mi>e</mi><mi>&amp;alpha;</mi></msub><msub><mi>e</mi><mi>&amp;beta;</mi></msub></mfrac><mo>)</mo></mrow><mo>=</mo><mi>a</mi><mi>r</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>n</mi><mrow><mo>(</mo><mfrac><mrow><mo>(</mo><msub><mi>K</mi><mn>1</mn></msub><mi>s</mi><mi>i</mi><mi>g</mi><mi>n</mi><mo>(</mo><msub><mover><mi>i</mi><mo>&amp;OverBar;</mo></mover><mi>&amp;alpha;</mi></msub><mo>)</mo><mo>)</mo></mrow><mrow><mo>(</mo><msub><mi>K</mi><mn>1</mn></msub><mi>s</mi><mi>i</mi><mi>g</mi><mi>n</mi><mo>(</mo><msub><mover><mi>i</mi><mo>&amp;OverBar;</mo></mover><mi>&amp;beta;</mi></msub><mo>)</mo><mo>)</mo></mrow></mfrac><mo>)</mo></mrow></mrow> <mrow><mi>n</mi><mo>=</mo><mfrac><mn>30</mn><mrow><mi>p</mi><mi>&amp;pi;</mi></mrow></mfrac><msub><mi>&amp;omega;</mi><mi>e</mi></msub><mo>=</mo><mfrac><mn>30</mn><mrow><mi>p</mi><mi>&amp;pi;</mi></mrow></mfrac><mfrac><mrow><msub><mi>d&amp;theta;</mi><mi>e</mi></msub></mrow><mrow><mi>d</mi><mi>t</mi></mrow></mfrac><mo>=</mo><mfrac><mn>30</mn><mrow><mi>p</mi><mi>&amp;pi;</mi></mrow></mfrac><mfrac><mrow><mi>d</mi><mi></mi><mi>a</mi><mi>r</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>n</mi><mrow><mo>(</mo><mfrac><msub><mi>e</mi><mi>&amp;alpha;</mi></msub><msub><mi>e</mi><mi>&amp;beta;</mi></msub></mfrac><mo>)</mo></mrow></mrow><mrow><mi>d</mi><mi>t</mi></mrow></mfrac></mrow> where _K1 is the fixed observation gain, is the observation error current of the stator α-axis, is the stator β-axis observation error current, are the observed currents on the α-axis and β-axis respectively, sign() is the sign function, e _α and e _β are the counter electromotive forces of the α-axis and β-axis respectively, and ω _e is the electrical angular velocity; (4) Subtract the estimated rotational speed n in step 3) from the given rotational speed n _ref , input the obtained rotational speed deviation Δn into the speed regulator to obtain the electromagnetic torque reference value T _eref , and convert the electromagnetic torque reference value to _Teref and the estimated speed n are sent to the current distributor to determine whether the actual speed is less than the rated speed, if so, the motor runs in the low speed zone, and enters step 5); otherwise, the motor runs in the high speed zone, and enters step 6); (5) Determine whether the load torque satisfies T _L ≤ T _N , determine the stator flux reference value ψ _sref and the electromagnetic torque reference value T _eref , and then enter step (7), where T _L is the load torque and T _N is the rated Torque, as follows; When T _{L ≤} T _N , there is no need for magnetization control, if if = 0, use i _d = 0 control, and carry out current distribution according to the following current distribution scheme: <mfenced open = "{" close = ""><mtable><mtr><mtd><msub><mi>i</mi><mrow><mi>d</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mn>0</mn></mtd></mtr><mtr><mtd><msub><mi>i</mi><mrow><mi>q</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><mrow><mn>2</mn><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub></mrow><mrow><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub></mrow></mfrac></mtd></mtr><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>f</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mn>0</mn></mrow></mtd></mtr></mtable></mfenced> Then the reference value of the stator flux linkage is obtained <mrow><msub><mi>&amp;psi;</mi><mrow><mi>s</mi><mi>r</mi><mi>e</mi><mi>f</mi>mi></mrow></msub><mo>=</mo><msqrt><mrow><msubsup><mi>&amp;psi;</mi><mi>m</mi><mn>2</mn></msubsup><mo>+</mo><msup><mrow><mo>(</mo><mfrac><mrow><mn>2</mn><msub><mi>L</mi><mi>q</mi></msub><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub></mrow><mrow><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub></mrow></mfrac><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt></mrow> When T _L >T _N , the q-axis current has reached the rated value, and magnetization control is required, so i _q =i _qN , and the d-axis current i _d =0 is used for control, and the current distribution is performed according to the following current distribution scheme: <mfenced open = "{" close = ""><mtable><mtr><mtd><msub><mi>i</mi><mrow><mi>d</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mn>0</mn></mtd></mtr><mtr><mtd><msub><mi>i</mi><mrow><mi>f</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><mrow><mn>2</mn><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>-</mo><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub><msub><mi>i</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub></mrow><mrow><mn>3</mn><msub><mi>pM</mi><mi>f</mi></msub><msub><mi>i</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub></mrow></mfrac></mtd></mtr><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>q</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><msub><mi>i</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub></mrow></mtd></mtr></mtable></mfenced> Then the reference value of the stator flux linkage is obtained as: <mrow><msub><mi>&amp;psi;</mi><mrow><mi>s</mi><mi>r</mi><mi>e</mi><mi>f</mi>mi></mrow></msub><mo>=</mo><msqrt><mrow><msup><mrow><mo>(</mo><msub><mi>&amp;psi;</mo>mi><mi>m</mi></msub><mo>+</mo><mfrac><mrow><mn>2</mn><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>-</mo><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub><msub><mi>i</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub></mrow><mrow><mn>3</mn><msub><mi>pi</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub></mrow></mfrac><mo>)</mo></mrow><mn>2</mn></msup><mo>+</mo><msup><mrow><mo>(</mo><msub><mi>L</mi><mi>q</mi></msub><msub><mi>i</mi><mrow><mi>q</mi><mi>N</mi></mrow></msub><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt></mrow> Among them, i _dref and i _qref are the d-axis and q-axis current reference values respectively, i _qN is the rated value of the q-axis current; i _fref is the excitation current reference value; L _d and L _q are the d-axis and q-axis inductances respectively, M _f is the mutual inductance between the armature and the field winding; ψ _m is the flux linkage of the permanent magnet; ψ _d , ψ _q are the d-axis and q-axis flux linkages respectively; ψ _s is the stator flux linkage, and ψ _sref is the reference value of the stator flux linkage ; (6) First judge whether the given speed is less than the field-weakening base speed n _flux , if so, keep the d-axis current i _d = 0, adopt the field current i _f to weaken the field, and carry out current distribution according to the following current distribution scheme: <mfenced open = "{" close = ""><mtable><mtr><mtd><msub><mi>i</mi><mrow><mi>q</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><mrow><mn>2</mn><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mrow><mrow><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub></mrow></mfrac></mtd></mtr><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>d</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mn>0</mn></mrow></mtd></mtr><mtr><mtd><msub><mi>i</mi><mrow><mi>f</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><msub><mi>&amp;psi;</mi><mi>m</mi></msub><msub><mi>M</mi><mi>f</mi></msub></mfrac><mo>(</mo><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>-</mo><mn>1</mn><mo>)</mo></mtd></mtr></mtable></mfenced> Then the reference value of the stator flux linkage is obtained as: <mrow><msub><mi>&amp;psi;</mi><mrow><mi>s</mi><mi>r</mi><mi>e</mi><mi>f</mi>mi></mrow></msub><mo>=</mo><msqrt><mrow><msup><mrow><mo>(</mo><msub><mi>&amp;psi;</mo>mi><mi>m</mi></msub><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>)</mo></mrow><mn>2</mn></msup><mo>+</mo><msup><mrow><mo>(</mo><mfrac><mrow><mn>2</mn><msub><mi>L</mi><mi>q</mi></msub><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mrow><mrow><mn>3</mn><msub><mi>p&amp;psi;</mi><mi>m</mi></msub><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub></mrow></mfrac><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt></mrow> If the given speed reaches the field-weakening base speed _nflux , then the excitation current if reaches the rated value, continue to use the _{d-axis current i d field} -weakening, and carry out current distribution according to the following current distribution scheme: <mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>q</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><mrow><mn>2</mn><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub></mrow><mrow><mn>3</mn><mi>p</mi><mo>{</mo><msub><mi>&amp;psi;</mi><mi>m</mi></msub><mo>+</mo><mfrac><mrow><mo>(</mo><msub><mi>L</mi><mi>d</mi></msub><mo>-</mo><msub><mi>L</mi><mi>q</mi></msub><mo>)</mo></mrow><msub><mi>L</mi><mi>d</mi></msub></mfrac><mo>&amp;lsqb;</mo><mrow><mo>(</mo><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>-</mo><mn>1</mn><mo>)</mo></mrow><msub><mi>&amp;psi;</mi><mi>m</mi></msub><mo>+</mo><msub><mi>M</mi><mi>f</mi></msub><msub><mi>I</mi><mrow><mi>r</mi><mi>N</mi></mrow></msub><mo>&amp;rsqb;</mo><mo>-</mo><msub><mi>M</mi><mi>f</mi></msub><msub><mi>I</mi><mrow><mi>r</mi><mi>N</mi></mrow></msub><mo>}</mo></mrow></mfrac></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>f</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mo>-</mo><msub><mi>I</mi><mrow><mi>f</mi><mi>N</mi></mrow></msub></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>i</mi><mrow><mi>d</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub><mo>=</mo><mfrac><mn>1</mn><msub><mi>L</mi><mi>d</mi></msub></mfrac><mo>&amp;lsqb;</mo><mrow><mo>(</mo><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>-</mo><mn>1</mn><mo>)</mo></mrow><msub><mi>&amp;psi;</mi><mi>m</mi></msub><mo>+</mo><msub><mi>M</mi><mi>f</mi></msub><msub><mi>I</mi><mrow><mi>f</mi><mi>N</mi></mrow></msub><mo>&amp;rsqb;</mo></mrow></mtd></mtr></mtable></mfenced> Reference value of stator flux linkage <mrow><msub><mi>&amp;psi;</mi><mrow><mi>s</mi><mi>r</mi><mi>e</mi><mi>f</mi>mi></mrow></msub><mo>=</mo><msqrt><mrow><msup><mrow><mo>(</mo><msub><mi>&amp;psi;</mo>mi><mi>m</mi></msub><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>)</mo></mrow><mn>2</mn></msup><mo>+</mo><msup><mrow><mo>(</mo><mfrac><mrow><mn>2</mn><msub><mi>L</mi><mi>q</mi></msub><msub><mi>T</mi><mrow><mi>e</mi><mi>r</mi><mi>e</mi><mi>f</mi></mrow></msub></mrow><mrow><mn>3</mn><mi>p</mi><mo>{</mo><msub><mi>&amp;psi;</mi><mi>m</mi></msub><mo>+</mo><mfrac><mrow><mo>(</mo><msub><mi>L</mi><mi>d</mi></msub><mo>-</mo><msub><mi>L</mi><mi>q</mi></msub><mo>)</mo></mrow><msub><mi>L</mi><mi>d</mi></msub></mfrac><mo>&amp;lsqb;</mo><mrow><mo>(</mo><mfrac><msub><mi>&amp;omega;</mi><mrow><mi>e</mi><mi>N</mi></mrow></msub><msub><mi>&amp;omega;</mi><mi>e</mi></msub></mfrac><mo>-</mo><mn>1</mn><mo>)</mo></mrow><msub><mi>&amp;psi;</mi><mi>m</mi></msub><mo>+</mo><msub><mi>M</mi><mi>f</mi></msub><msub><mi>I</mi><mrow><mi>f</mi><mi>N</mi></mrow></msub><mo>&amp;rsqb;</mo><mo>-</mo><msub><mi>M</mi><mi>f</mi></msub><msub><mi>I</mi><mrow><mi>f</mi><mi>N</mi></mrow></msub><mo>}</mo></mrow></mfrac><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt></mrow> Among them, I _fN is the rated value of excitation current, ω _eN is the rated electrical angular velocity; (7) Subtract the actual stator flux estimated value ψ _s obtained in step (3) from the stator flux reference value ψ _sref to obtain the stator flux deviation Δψ _s , and subtract the step from the electromagnetic torque reference value T _eref The actual electromagnetic torque estimation value T _e in (3) is used to obtain the electromagnetic torque deviation △T _e , and then △ψ _s is sent to the hysteresis comparator to obtain the torque control signal τ, and △T _e is sent to the hysteresis comparator Get the flux linkage control signal φ, and the three control signals τ, φ, θ select the switch state through the switch table to drive the main power converter; At the same time, the excitation current if collected in step (1) is sent to the DC excitation pulse width modulation module together with the excitation current reference value _{i fref} obtained in step (5) or (6) after signal conditioning and A/D conversion , the operation outputs 4 pulse width modulation signals to drive the excitation power converter. 2. The position sensorless direct torque control method of a hybrid excitation synchronous motor according to claim 1, characterized in that the DC excitation pulse width modulation module in the step (7) is a space vector pulse width modulation module.