阅读说明：本技术 基于mtpa无参数无位置传感的永磁同步电机控制方法 (MTPA-based parameter-free position-sensing-free permanent magnet synchronous motor control method ) 是由 刘宁 郭伟 杨妍 于 2019-10-28 设计创作，主要内容包括：本发明公开了基于MTPA无参数无位置传感的永磁同步电机控制方法,它含有一种电流控制模式,包括步骤1：接收用户输入给定电流Idq*和γ角,计算出Id_r*和Iq_r*；步骤2：根据Id_r*和Iq_r*在MTPA数据表查找对应的α角；步骤3：利用α角、Id_r*和Iq_r*计算出Id_Ref和Iq_Ref；步骤4：通过对电流Iq_Ref和电机实时运行的反馈电流Iq输入到PLL锁相环中获取θv,利用对电流Id_Ref和电机实时运行的反馈电流Id的PI处理获取Vq,因为在MTPA模式下,Vd＝0,Vdq＝Vq,利用θv和Vdq可以获取Vα和Vβ,从而实现对电流的控制,它算法精简,运算简单,减少芯片资源占用,降低成本,解决了在对电机电阻Rs、电感Lq、Lq和磁通λm有高度依赖性的的瓶颈问题。(The invention discloses a method for controlling a permanent magnet synchronous motor without parameter and position sensing based on MTPA, which comprises a current control mode, a step 1 of receiving given current Idq and a gamma angle input by a user and calculating Id _ r and Iq _ r, a step 2 of searching a corresponding α angle in an MTPA data table according to Id _ r and Iq _ r, a step 3 of calculating Id _ Ref and Iq _ Ref by using α angle, Id _ r and Iq _ r, and a step 4 of inputting the current Iq _ Ref and feedback current Iq operated by the motor in real time into a PLL phase-locked loop to obtain theta V and obtaining Vq by using PI processing of the current Id _ Ref and the feedback current Id operated by the motor in real time, wherein Vd is 0 and Vq, Vd is Vq, V α and V β can be obtained by using the theta V and the Vq in the MTPA mode, thereby realizing control of the current, reducing the current occupancy and the inductance dependence on the chip and reducing the cost of inductance.)

1. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method is characterized by comprising the following steps of: it contains a current control mode, including the following steps:

step 1: receiving given current Idq and a gamma angle input by a user, wherein the gamma angle is an included angle between a current vector Idq and a q axis, and calculating Id _ r and Iq _ r, wherein the Id _ r and the Iq _ r are a current value of the current vector Idq on a d axis and a current value of the q axis in a rotor rotating coordinate system dq, and the given current Idq and the gamma angle are data according with an MTPA mode;

step 2, searching corresponding α angles in an MTPA data table according to Id _ r and Iq _ r, wherein the α angle is an included angle between a rotor coordinate system dq and a voltage coordinate system VdVq, and the MTPA data table refers to data obtained in a mode of maximum moment per ampere;

step 3, calculating Id _ Ref and Iq _ Ref by using α angles, Id _ r and Iq _ r, wherein the Id _ Ref and the Iq _ Ref are projections of a current vector Idq on a Vd axis and a Vq axis in a voltage coordinate system VdVq;

and 4, inputting the current Iq _ Ref and the feedback current Iq of the real-time operation of the motor into a PLL phase-locked loop to acquire theta V, wherein the theta V is an included angle between a voltage vector and a static coordinate system αβ, and acquiring Vq by PI processing of the current Id _ Ref and the feedback current Id of the real-time operation of the motor, wherein Vd is 0 and Vq is Vq, and V α and V β can be acquired by utilizing the theta V and the Vdq in the MTPA mode, so that the current control is realized.

2. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method according to claim 1, characterized in that: id _ Ref and Iq _ Ref are obtained by:

Id_ref＝Id_r*×cos(α)+Iq_r*×sin(α)

Iq_ref＝-Id_r*×sin(α)+Iq_r*×cos(α)。

3. the MTPA-based parameter-free position-sensing-free permanent magnet synchronous motor control method according to claim 1 or 2, characterized in that: id _ r and Iq _ r of step 1 are calculated as follows:

Id_r*＝-Idq*×sin(γ)

Iq_r*＝Idq*×cos(γ)。

4. the MTPA-based parameter-free position-sensing-free permanent magnet synchronous motor control method according to claim 1, 2 or 3, characterized in that: the MTPA data sheet is data obtained experimentally or data obtained by theoretical calculations or data obtained by finite element analysis software of a computer.

5. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method according to claim 4, wherein: in the current control mode, when the voltage value Vq is greater than or equal to the set threshold value Vmax, the PI regulator enters a saturation state, the voltage output is limited to Vmax, Id is not controlled any more, and the state is a field weakening control mode.

6. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method is characterized by comprising the following steps of: it contains a speed control mode, including the following steps:

step 1, receiving a given speed spd instruction input by a user and a gamma angle, and enabling a vector angle of a voltage vector Vdq to rotate according to the given speed spd to obtain theta v, wherein the theta v is an included angle between the voltage vector and a static coordinate system αβ, and the gamma angle is an included angle between a current vector Idq and a q axis;

step 2, calculating Id _ r and Iq _ r according to feedback current Id and gamma angles of real-time running of the motor, wherein the Id _ r and the Iq _ r are current values of a d axis and a q axis of a current vector Idq in a rotor rotating coordinate system dq, the Id _ r and the Iq _ r are data conforming to an MTPA mode, corresponding β angles are searched in an MTPA data table by using the Id _ r and the Iq _ r, and β is an included angle between a voltage vector Vdq and the current vector Idq in the MTPA mode;

and 3, obtaining theta iv and theta V-theta i, and obtaining the voltage Vq by PI processing on the angles β and theta iv, wherein Vd is 0 and Vdq is Vq in the MTPA mode, and V α and V β can be obtained by the theta V and the Vdq, so that the control of the rotating speed is realized.

7. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method according to claim 6, wherein: the MTPA data sheet is data obtained experimentally or data obtained by theoretical calculations or data obtained by finite element analysis software of a computer.

8. The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method is characterized in that in the step 2, a feedback current Iq of the motor running in real time is used as one input of a PLL, the other input Iq of the PLL is set to be 0, Iq is the projection of a current vector Idq on a Vq axis in a VdVq coordinate system, and the output angles theta I and theta I of the PLL enable the Iq to be 0, which is the angle generated by the resolution I α and I β of the PLL.

9. The MTPA-based parameter-free position-sensing-free permanent magnet synchronous motor control method according to claim 8, wherein: θ v is obtained by:

θν＝∫spd×(pole_pair×360×Δt÷60)·dt

wherein: spd is the speed value, Pole _ pair is the motor Pole pair number, Δ t is the time variable.

10. The MTPA-based parameter-free position-sensing-free permanent magnet synchronous motor control method according to claim 9, wherein: in the speed control mode, when the voltage value Vq is greater than or equal to a set threshold value Vmax, the PI regulator enters a saturation state, the output of the PI regulator is limited to Vmax, and the PI regulator is automatically switched into a weak magnetic control mode.

The technical field is as follows:

the invention relates to a permanent magnet synchronous motor control method based on MTPA (maximum Transmission Power Amplifier) parameter-free and position-sensing-free.

Background art:

at present, the control method of the position sensor-free vector control permanent magnet synchronous motor generally has three modes, namely a constant torque control mode, a constant rotating speed control mode and a constant air volume control mode.

For example, US7525269 discloses a position sensorless 3-step motor vector controller, which only discloses a current torque control mode, performing constant torque control.

Chinese patent CN103929109(a) also discloses a constant rotation speed control method based on position sensor-free vector control of a permanent magnet synchronous motor.

As shown in fig. 1, a block diagram of a general constant torque control is shown in fig. 1, because the torque T is related to only the q-axis current, a torque calculation formula T is K × iq0, and a torque set value T is converted into a set current iq0 of the q-axis, so that the control of the constant torque can be realized by using a q-axis PI current loop for closed-loop control.

The most conventional FOC theory of the control method of the position-sensorless vector control permanent magnet synchronous motor is mostly established on a rotor coordinate system (rotor frame). When the rotor position is unknown, the position sensorless algorithm is used to estimate the rotor position so that the FOC theory can continue to work. The rotor position is estimated by adopting theory and motor related parameters, the mathematical model is complex, the operation is time-consuming and complex, a large amount of control chip (microprocessor MCU) resources are occupied, the requirement on the microprocessor MCU is high, and the cost is high. In addition, the FOC theory has high dependency on motor parameters such as motor resistance Rs, inductance Lq, Lq and magnetic flux lambda m, so that the scheme application range is narrow.

The invention content is as follows:

the invention aims to provide a MTPA (maximum Transmission Power Amplifier) -based parameter-free position-sensing-free permanent magnet synchronous motor control method, which solves the technical problems that in the prior art, the conventional FOC theory for estimating the rotor position is closely related to the related parameters of a motor by adopting a theory, a mathematical model is complex, the operation is time-consuming and complex, a large amount of control chip resources are occupied, the requirement on a microprocessor MCU (microprogrammed control Unit) is high, and the cost is high.

The object of the present invention is achieved by the following means.

The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method is characterized by comprising the following steps of: it contains a current control mode, including the following steps:

step 1: receiving given current Idq and a gamma angle input by a user, wherein the gamma angle is an included angle between a current vector Idq and a q axis, and calculating Id _ r and Iq _ r, the Idq _ r and the Iq _ r are a current value of a d axis and a current value of a q axis projected by the current vector Idq in a rotor rotating coordinate system dq, and the given current Idq and the gamma angle are data conforming to an MTPA mode;

step 2, searching corresponding α angles in an MTPA data table according to Id _ r and Iq _ r, wherein the α angle is an included angle between a rotor coordinate system dq and a voltage coordinate system VdVq, and the MTPA data table refers to data obtained in a mode of maximum moment per ampere;

step 3, calculating Id _ Ref and Iq _ Ref by using α angles, Id _ r and Iq _ r, wherein the Id _ Ref and the Iq _ Ref are projections of a current vector Idq in a voltage coordinate system VdVq;

and 4, inputting the current Iq _ Ref and the feedback current Iq of the real-time operation of the motor into a PLL phase-locked loop to obtain theta V, wherein the theta V is an included angle between a voltage vector and a static coordinate system αβ, and obtaining Vq by PI processing of the current Id _ Ref and the feedback current Id of the real-time operation of the motor, wherein Vd is 0 and Vdq is Vq in the MTPA mode, and V α and V β can be obtained by the theta V and the Vdq, so that the current control is realized.

The above-mentioned Id _ Ref and Iq _ Ref are obtained by:

Id_ref＝Id_r^*×cos(α)+Iq_r^*×sin(α)

Iq_ref＝-Id_r^*×sin(α)+Iq_r^*×cos(α)。

id _ r and Iq _ r of the above step 2 are calculated as follows:

Id_r^*＝-Idq^*×sin(γ)

Iq_r^*＝Idq^*×cos(γ)。

the MTPA data table is data obtained through experiments or data obtained through theoretical calculation or data obtained through finite element analysis software of a computer.

In the above current control mode, when the voltage Vq is greater than or equal to the set threshold Vmax, the PI regulator enters a saturation state, the voltage output is limited to Vmax, and Id is no longer controlled, which is a field weakening control mode.

The MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method is characterized by comprising the following steps of: it contains a speed control mode, including the following steps:

step 1, receiving a given speed spd instruction input by a user and a gamma angle, and enabling a vector angle of a voltage vector Vdq to rotate according to the given speed spd to obtain theta v, wherein the theta v is an included angle between the voltage vector and a static coordinate system αβ, and the gamma angle is an included angle between a current vector Idq and a q axis;

calculating Id _ r and Iq _ r according to feedback current Id and gamma angles of real-time running of the motor, wherein the Id _ r and the Iq _ r are current values of a d axis and a q axis of a current vector Idq in a rotor rotating coordinate system dq, the Id _ r and the Iq _ r are data conforming to an MTPA mode, corresponding β angles are searched in an MTPA data table by using the Id _ r and the Iq _ r, and β is an included angle between a voltage vector Vdq and the current vector Idq in the MTPA mode, so that the current vector Idq Vd and the axes are coincident to obtain an angle theta i;

and 3, obtaining theta iv and theta V-theta i, and obtaining the voltage Vq by PI processing on the angles β and theta iv, wherein Vd is 0 and Vdq is Vq in the MTPA mode, and V α and V β can be obtained by the theta V and the Vdq, so that the control of the rotating speed is realized.

The MTPA data table is data obtained through experiments or data obtained through theoretical calculation or data obtained through finite element analysis software of a computer.

In the step 2, the feedback current Iq of the real-time operation of the motor is used as one input of the PLL phase-locked loop, the other input Iq of the PLL phase-locked loop is set to 0, Iq is the projection of the current vector Idq on the Vq axis in the VdVq coordinate system, and the output angle θ I of the PLL phase-locked loop, θ I, so that Iq is 0, which is the angle generated by the PLL phase-locked loop analysis I α, I β.

The above-mentioned θ v is obtained by:

θν＝∫spd×(pole_pair×360×Δt÷60)·dt

wherein: spd is the speed value, Pole _ pair is the motor Pole pair number, Δ t is the time variable.

In the speed control mode, when the voltage value Vq is greater than or equal to a set threshold value Vmax, the PI regulator enters a saturation state, the output of the PI regulator is limited to Vmax, and the PI regulator is automatically switched into a weak magnetic control mode.

Compared with the prior art, the invention has the beneficial effects that:

1) the MTPA-based parameter-free and position-sensing-free permanent magnet synchronous motor control method does not analyze the position of a rotor by using a flux observer any more, so that the calculation time of a CPU (central processing unit) is greatly reduced, the position-free motor control becomes simpler and more direct and more intuitive, the current and speed control mode of the motor is completed by two paths of decoupled PI regulators at the same time, and the stability and the dynamic response of the control are superior to those of a multi-stage ridge-and-socket control loop;

2) in the current and speed control mode, the motor is optimized to make the current run along the calibrated MTPA track. The motor has a full-load starting function, the operation range of the motor comprises BEMF-free to field weakening control, and the function is complete.

3) The invention relates to a permanent magnet synchronous motor control method based on MTPA non-parameter and non-position sensing, wherein a PLSL-MTPA mathematical model is no longer based on a single rotor coordinate system, the algorithm projects a motor current vector on a current and voltage coordinate system simultaneously, and the non-position control is completed in a way of analyzing a vector included angle.

4) A PLSL-MTPA mathematical model of the MTPA parameter-free position-sensing-free permanent magnet synchronous motor control method is an optimized motor control technology without a position sensor of motor parameters, and the technology solves the bottleneck problem that the motor resistance Rs, the inductance Lq, the Lq and the magnetic flux lambda m have high dependency in the process of position-free and optimized control of a motor.

Description of the drawings:

fig. 1 is a control block diagram of a conventional position sensorless vector control permanent magnet synchronous motor FOC.

Fig. 2 is a perspective view of a permanent magnet synchronous motor of the present invention;

fig. 3 is a perspective view of a motor controller of the permanent magnet synchronous motor of the present invention;

fig. 4 is a cross-sectional view of a permanent magnet synchronous motor of the present invention;

FIG. 5 is a schematic block diagram of a motor controller of the permanent magnet synchronous motor of the present invention;

FIG. 6 is a corresponding circuit diagram of FIG. 5;

FIG. 7 is a schematic illustration of a stationary coordinate system ABC of a three-phase permanent magnet synchronous machine;

fig. 8 is a schematic illustration of a stationary orthogonal coordinate system αβ of a three-phase permanent magnet synchronous machine;

FIG. 9 is a relationship diagram of coordinate systems for vector control of a three-phase permanent magnet synchronous motor;

FIG. 10 is a diagram of an orthogonal coordinate system αβ in accordance with the present invention in relation to a rotor coordinate system dq;

FIG. 11 is a graph of time domain variables of thetav, thetai and thetar at the same frequency according to the present invention;

FIG. 12 is a graph plotting the angular relationship of the voltage vector and the current vector for the present invention;

FIG. 13 is a schematic diagram of the MTPA mode of the present invention;

FIG. 14 is a schematic diagram of the current control mode of the present invention;

FIG. 15 is a schematic block diagram of the current control mode of the present invention;

FIG. 16 is a schematic block diagram of the speed control mode of the present invention;

fig. 17 is a graph of the analytical data corresponding to angles α with Id _ r and Iq _ r according to the present invention;

fig. 18 is an analysis data graph of β corners corresponding to Id _ r and Iq _ r according to the present invention.

The specific implementation mode is as follows:

the present invention will be described in further detail below with reference to specific embodiments and with reference to the accompanying drawings.

As shown in fig. 2, 3, and 4, for example: the invention is supposed to be a three-phase permanent magnet synchronous motor, which comprises a motor controller 2 and a motor monomer 1, wherein the motor monomer 1 comprises a stator assembly 12, a rotor assembly 13 and a casing assembly 11, the stator assembly 13 is installed on the casing assembly 11, the rotor assembly 13 is sleeved on the inner side or the outer side of the stator assembly 12 to form the three-phase permanent magnet synchronous motor, the motor controller 2 comprises a control box 22 and a control circuit board 21 installed in the control box 22, the control circuit board 21 generally comprises a power circuit, a microprocessor, a bus voltage detection circuit and an inverter, the power circuit supplies power to each part of the circuits, the bus voltage detection circuit inputs direct current bus voltage Uabc to the microprocessor, the microprocessor controls the inverter, and the inverter controls the on-off of each phase coil winding of.

As shown in fig. 5 and 6, it is assumed that the phase line current detection circuit of the 3-phase brushless dc permanent magnet synchronous motor inputs the currents Ia, Ib, and Ic of the respective phases to the microprocessor. After an alternating current INPUT (AC INPUT) passes through a full-wave rectifying circuit composed of diodes D7, D8, D9 and D10, a direct current bus voltage Vdc bus is output at one end of a capacitor C1, the direct current bus voltage Vdc bus is related to INPUT alternating current voltage, a microprocessor INPUTs PWM signals to an inverter, the inverter is composed of electronic switching tubes Q1, Q2, Q3, Q4, Q5 and Q6, and control ends of the electronic switching tubes Q1, Q2, Q3, Q4, Q5 and Q6 are respectively controlled by 6 paths of PWM signals (P1, P2, P3, P4, P5 and P6) output by the microprocessor.

As shown in FIG. 7, the three phase motor currents Ia, Ib, Ic. have a phase angle of 120 degrees in the time domain, commonly referred to as the stationary coordinate system, the three time domain currents can be reduced to two orthogonal currents I α, I β, as shown in FIG. 8, described by a triangular vector diagram, see FIG. 9, whose mathematical relationship is:

if we stand on a rotating platform with the same frequency to observe I α, I β, and introduce a rotor rotating coordinate system dq, the positive rotation characteristic is cancelled, and only the phase characteristic is reserved.

I_d＝I_α*cos(θ)+I_β*sin(θ)

I_q＝I_β*cos(θ)-I_α*sin(θ)

- - - - (equation 2)

As shown in fig. 10, we introduce the variable θ in the PARK transformation, i.e. the observation azimuth angle we observe I α, I β, I α, I β are resolved from different observation azimuths, and the projections of the I α, I β on different rotating platforms (i.e. coordinate systems) are different, once an observation angle is selected, the PARK transformation changes the positive rotation I α, I β into direct current Id, Iq. in a permanent magnet synchronous motor without a position sensor, the selection of θ becomes the most important problem, the north pole of the rotor magnetic field is usually located at 0 degree in the motor control, the rotor rotates for 360 degrees once, and the relationship between the rotor position and the pole pair number is as follows:

θ r — pol _ pair × θ 0, where θ 0 is the rotor mechanical angle, and pol _ pair is the motor Pole pair number.

In most position sensorless permanent magnet synchronous motor controls, of course, the rotor mechanical angle is unknown. The central task of the algorithm is to estimate θ r. Once θ r is estimated, the vector control algorithm for the motor can be implemented immediately. However, the traditional algorithm for estimating the theta r by the FOC theory is extremely complex, long in operation time, complex in mathematical model and highly dependent on the parameters of the motor.

The invention relates to a MTPA (maximum power supply) parameter-free position-sensing-free permanent magnet synchronous motor control method (PLSL-MTPA), which is based on a PLSL-MTPA algorithm (MTPA). in the PLSL-MTPA, I α and I β are analyzed by using another method, namely I α and I β are analyzed by establishing a rotating platform by using different theta angles.

The invention introduces theta v and theta i which respectively represent the included angles between the voltage vector and the current vector and the static coordinate system ABC, and the included angles are shown in figure 12.

In the speed control mode, thetav is integrated from the open loop speed, which is used to generate V α, V β, which in turn generates Va, Vb, Vc., thetai phase locked loop resolves the angle that is generated by I α, I β making Iq 0.

The (I α, I β) by θ I is converted by Park according to the above equation 2 and (Id, 0):

Id＝Iα×Cos(θi)+Iβ×sin(θi)

0＝Iβ×Cos(θi)－Iα×sin(θi)

in the theory of synchronous machines, θ v, θ i, θ r are three time domain variables of the same frequency, taking phase a as an example, when va (t) leads ia (t) β, as shown in fig. 12:

Va(t)＝Vabc×cos(θv)＝Vabc×cos(wt+β)

Ia(t)＝Iabc×cos(θi)＝Iabc×cos(wt)

wherein Vabc is a voltage vector synthesized by windings of the A phase, the B phase and the C phase, a current vector synthesized by windings of the IabcA phase, the B phase and the C phase, w is an angular velocity, t is time, and β is an included angle between the voltage vector Va (t) of the A phase and the current vector Ia (t).

The relationship among thetav, thetai and thetar is as follows:

β θ v θ i- -equation 3

Thetar-thetav- α -formula 4

The time-domain relationship of θ v, θ I and θ r is shown in fig. 11, and the core of the PLSL-MTPA algorithm is to always maintain θ v and θ I at a given angle of β to form a velocity pattern according to the above formula 3, or to form a current pattern by projecting I α and I β onto a voltage coordinate system (i.e., VdVq coordinate system) according to the above formula 4 to satisfy α angle, because PLSL-MTPA always keeps Vd equal to 0 and Vdq equal to Vq to form a vector diagram between voltage, current and rotor, which is shown in fig. 13, and fig. 13 is a simplified PLSL-MTPA vector diagram.

In fig. 13, an angle α may be obtained as β + γ, where angle α is the angle between the rotor coordinate system dq and the voltage coordinate system VdVq in the MTPA mode, angle β is the angle between the voltage vector Vdq and the current vector Idq in the MTPA mode, and γ is the angle between the current vector dq and the q-axis.

In fig. 14 and 15, in the voltage coordinate system-VdVq coordinate system, Vd is always set to 0 and Vdq is set to Vq, in the current control mode, θ V can be obtained by performing PLL phase-locked loop processing on the projection of the current vector Idq of I α and I β on the q axis and the projection of the current vector Idq on the Vq axis in the VdVq coordinate system, and Vq can be obtained by PI processing on the projection of the current vector Idq of I α and I β on the d axis and the projection of the current vector Idq on the Vd axis in the VdVq coordinate system, and since Vd is set to 0 and Vdq is set to Vq, the direct current amount can be converted into positive rotation amounts V α and V β by using θ V and Vdq.

As shown in fig. 14 and 16, another control mode of PLSL-MTPA of the present invention, i.e., a speed control mode, is based on the following principle: the voltage vector Vdq is rotated according to a given speed command spd, namely, the open loop control is operated,

θν＝∫spd×(pole_pair×360×Δt÷60)·dt

wherein spd is a speed value, Pole _ pair is a motor Pole pair number, and Δ t is a time variable;

the PLL phase-locked loop generates θ i by superimposing Idq on the Vd axis (that is, Iq is 0), obtains an angle difference θ iv- θ i, and obtains a voltage vector Vdq-PI (θ iv- β), and obtains θ V and Vdq, thereby converting the positive rotation amount into a direct current amount to obtain V α, V β.

The current PI device of the above two control modes obtains Vdq by using angle or current error control, wherein: speed mode:

Δ＝θiv-β

current mode:

Δ＝I_{d_ref}-I_d

and voltage vector Vdq ═ PI (Δ), Vabc is generated from θ v and Vdq.

The two modes are calculated in different ways for thetav and Vdq.

The PLSL-MTPA static full-load starting of the invention is started by using the maximum current Idq _ Max, when the motor is in a resistance state at low speed, the current and the voltage are in the same phase, the current PI controller tends to be saturated at the maximum current, the Idq _ Max is used for driving the motor, when the rotating speed begins to rise, the back electromotive force is also enhanced, and the current voltage difference angle β is gradually not 0, so that the current PI controller enters a normal working range, the difference angle between Vdq and Idq changes along with the actual load, the motor current also responds.

The conventional FOC theory is mostly based on a rotor coordinate system (rotor frame). When the rotor position is unknown, the position-sensorless algorithm can be used for estimating the rotor position, so that the FOC theory can be continued to be used, and the PLSL-MTPA control method of the invention is different from the conventional FOC in that the PLSL-MTPA control method is separated from the dependency on a rotor coordinate system from the beginning, and an angle conversion scheme which is independent of motor parameters is adopted and the phase angle of current voltage is adjusted to realize synchronous control on the motor. The design concept greatly simplifies the control process of the motor without the position sensor.

The PLSL-MTPA control method of the invention conforms to 4 control laws:

control law 1:

under synchronous operating conditions, overall control of the synchronous machine is achieved by maintaining a controllable angle β between the current vector and the voltage vector, the β angle is also commonly referred to as the power factor angle.

Control law 2:

under synchronous operating conditions, the rotor position of the synchronous machine can be determined by adding a controllable angle α to the voltage vector, the α angle may lead or lag the voltage vector, based on the α angle already given, a voltage vector is applied to the synchronous machine, the synchronous condition of which can continue, i.e., the synchronous machine is controllable.

Law of control 3:

the unit current maximum torque MTPA control can be accomplished by converting the current command to α degrees, the generation of α degrees thereof both follow the MTPA principle and are used for control of the synchronous machine by control law 1 and control law 2.

Control law 4:

the rotor position estimated by control law 2 is the actual motor rotor position only when the current control command follows the MTPA trajectory and is converted to α degrees using the MTPA criteria.

Control law 5:

the voltage to speed ratio may be approximated as BEMF when the motor is operating at low current. The synchronous machine operating state can be determined by comparing this value with a threshold value.

The speed mode of PLSL-MTPA is actually an open loop control of the speed at which the band load can also enter and exit the weak magnetic region. In addition to being simple and optimizable, its speed and position vary only with the command. The characteristic has wide application prospect in dragging control.