CN114696696A - Full-speed area unified vector control method and system of permanent magnet synchronous motor - Google Patents

Abstract

The invention provides a method and a system for unified vector control of a full-speed area of a permanent magnet synchronous motor, which relate to the technical field of motor vector control, a dq axis coordinate system is subjected to integral rotation with a current angle beta along the rotation direction of the motor, the vector control of the permanent magnet synchronous motor is sequentially carried out on the basis of improved Park transformation, optimization operation of the current angle beta and improved Park inverse transformation, the maximum torque-current ratio control of a medium-low speed area and the low-speed area flux weakening control of the high-speed area are automatically realized by the same optimization operation of the current angle beta on the basis of the characteristic that the motor efficiency of a nearest working point from the center of a coordinate system is close to the highest under the condition that the working points of the medium-low speed area and the high-speed area simultaneously meet an electromagnetic torque equation, a current limit circular equation and a voltage limit elliptical equation of the motor, the unified vector control of the full-speed area can be realized, and the running stability of the permanent magnet synchronous motor in the mode switching process of different rotating speed areas is ensured.

Description

Full-speed area unified vector control method and system of permanent magnet synchronous motor

Technical Field

The invention relates to the technical field of motor vector control, in particular to a full-speed area unified vector control method and system of a permanent magnet synchronous motor.

Background

In recent years, with the improvement of social energy-saving and environment-friendly consciousness, the rapid development of power electronic technology and the improvement of the performance-price ratio of rare earth permanent magnet materials, the permanent magnet synchronous motor is widely applied to the fields of rail transit, wind power generation, electric automobiles, indoor air purification, mine tunnel ventilation and the like by virtue of the characteristics of simple structure, high efficiency and wide speed regulation range.

In the existing vector control technology of the permanent magnet synchronous motor, a base speed point of the motor needs to be calculated or detected, a medium-low speed region is determined when the running rotating speed of the motor is lower than the base speed point, and a high speed region is determined when the running rotating speed of the motor is higher than the base speed point. The medium-low speed area is usually controlled by adopting a maximum torque-current ratio, the high-speed area is limited by the direct-current end voltage of a converter, the speed regulation range of the motor needs to be widened through weak magnetic control, and the operation stability of the motor in the high-speed area is improved. The above vector control technology process needs to distinguish the medium-low speed area and the high-speed area, and then adopts different control strategies in the two areas, which increases the difficulty of programming, and may also cause the problem of system instability in the adjusting and switching process of different speed areas.

In the prior art, an implementation based on I is proposed_dFirstly, determining the basic speed of the motor, and if the motor is in a working condition below the basic speed, performing maximum torque-current ratio control; if the motor is in the working condition above the basic speed, carrying out flux weakening control; wherein, when carrying out weak magnetism control, the traditional rotating coordinate system dq axis is wholly rotated by an angle anticlockwise, a new rotating coordinate system is virtualized, and I-based realization is realized_dThe uniform vector control mode is optimized through the weak magnetic control of 0, but the method needs to acquire a base speed point, then controls the motor vector in a medium-low speed region and a high speed region based on the base speed point to be separately programmed, and needs to acquire a weak magnetic control data table of the relation between the torque and the rotation speed and the current angle in advance through measurement and calibration, so that the complexity is high.

Disclosure of Invention

In order to solve the problems that the prior vector control mode of the permanent magnet synchronous motor needs to acquire a base speed point of the motor, needs to distinguish different speed areas and has high complexity, the invention provides a full-speed area unified vector control method and a full-speed area unified vector control system of the permanent magnet synchronous motor, which do not need to calculate or detect the base speed point of the motor, automatically realize the maximum torque-current ratio control of a medium-low speed area and the field weakening control of a high-speed area, namely realize the full-speed area unified vector control of the permanent magnet synchronous motor, and ensure the running stability of the permanent magnet synchronous motor in the switching process of different rotating speed area modes.

In order to achieve the technical effects, the technical scheme of the invention is as follows:

a full-speed area unified vector control method of a permanent magnet synchronous motor, wherein the full-speed area comprises a medium-low speed area and a high-speed area, and the full-speed area unified vector control method comprises the following steps:

s1, obtaining three-phase stator current, a rotor angle theta and a real-time rotating speed omega of the permanent magnet synchronous motor in real time, and performing Clark transformation on the three-phase stator current to obtain current i_αAnd i_β；

S2, integrally rotating the dq axis coordinate system along the rotation direction of the motor with a current angle beta to obtain d_newq_newRotating the coordinate system, based on the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (2);

s3, optimizing the current angle beta, namely adjusting the current angle beta when the current i is fed back by the q axis_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

s4, setting a given signal of a d-axis regulator of the permanent magnet synchronous motor to be i_drefAnd fixed to 0, and a limit value of the sub-current is set to i_smaxGiven rotation speed of omega_refBased on the real-time rotation speed omega and the given rotation speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i_qrefCarrying out amplitude limiting processing;

s5, calculating a given signal i of the d-axis regulator_drefAnd d-axis feedback current i_dnewThe deviation of (a) is determined,PI controlling the deviation to output a signal u_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPerforming PI control on the deviation, and outputting a signal u_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing;

s6, obtaining the optimal current angle beta based on the rotor angle theta and S3, and comparing the signal u_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefTo u, to u_αrefAnd u_βrefAnd performing space pulse modulation to form a PWM signal, and driving an inverter circuit to control the rotating speed of the permanent magnet synchronous motor by using the PWM signal.

In the technical scheme, a dq axis coordinate system is integrally rotated with a current angle beta along the rotation direction of a motor to obtain a new rotation coordinate system, vector control is performed on the permanent magnet synchronous motor on the basis of improved Park transformation, optimization operation of the current angle beta and improved Park inverse transformation in sequence, and on the basis of the characteristic that the motor efficiency of a working point closest to the circle center of the coordinate system is close to the highest under the condition that the working points of a medium-low speed area and a high-speed area simultaneously meet an electromagnetic torque equation, a current limit circular equation and a voltage limit elliptical equation of the motor, the optimization operation of the current angle beta is utilized to automatically realize the maximum torque-current ratio control of the medium-low speed area and the flux weakening control of the high-speed area, the base speed point of the motor does not need to be calculated or detected, the motor does not need to be judged to work in the medium-low speed area or the high-speed area, and unified vector control of the full-speed area is realized.

Preferably, in the dq axis coordinate system, the steady-state voltage equation of the permanent magnet synchronous motor is as follows:

the electromagnetic torque equation of the permanent magnet synchronous motor is as follows:

wherein u is_d、u_qThe voltages of a d axis and a q axis of the motor are respectively; i.e. i_d、i_qD-axis current and q-axis current of the motor respectively; r is a stator resistor; l is_d、L_qD-axis and q-axis inductors respectively; omega is the electrical angular velocity, psi, of the motor_mA permanent magnet flux linkage of the motor; p is a radical of_nThe number of pole pairs of the motor is shown. Maximum current i for sustainable operation of stator windings of d-axis and q-axis current receiving motors_maxSatisfies the current limit circle equation:

d. maximum output voltage u of q-axis voltage inverter_qmaxSatisfies the relation:

wherein u is_dcFor the dc bus voltage of the inverter, the voltage limit elliptic equation is:

here, the voltage limit ellipse equation is obtained by considering that the voltage drop of the stator resistance in the high speed region is negligible with respect to the d and q axis inductance voltage drops.

Preferably, in step S2, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (a) is:

where θ represents a rotor angle and β represents a current angle of the entire rotation.

Here, due to the new d_newq_newThe rotating coordinate system is obtained on the basis that the traditional coordinate system rotates by a current angle, so the traditional Park transformation is improved, and the improved Park transformation matrix is as follows:

preferably, the specific procedure of the current angle β optimizing operation in step S3 is as follows:

s31, setting a search mark beta of a current angle beta as beta ChangFLG and setting the current angle beta as an initial value beta₀Each time the current angle beta increases or decreases, the step size is delta beta, the signal u_drefMaximum value of (1) is u_qmax；

S32, judging whether the real-time rotating speed omega of the motor reaches the given rotating speed omega or not_refSignal u_qrefWhether or not the maximum value u is reached_qmaxIf the given rotation speed is not reached and the signal u_qrefNot reaching the maximum value u_qmaxControlling the current rotating speed of the synchronous motor through a speed regulator; if the motor speed omega reaches the given speed omega_refOr signal u_qrefTo a maximum value u_qmaxIf yes, entering the current angle β optimization, and executing step S33;

s33, determining whether β ChangFLG is 1, if yes, increasing the current angle β by Δ β, and obtaining the q-axis feedback current i from step S2_qnewTo obtain the actual value i of the q-axis feedback current_{q1_new}Step S34 is executed; otherwise, reducing the current angle beta by delta beta to obtain the actual value i of the q-axis feedback current_{q2_new}Step S35 is executed;

s34, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudgment of i_{q1_new}Whether or not less than i_qminIf yes, let i_qmin＝i_{q1_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 0, go to step S36;

s35, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudging the actual value i of the q-axis feedback current_{q2_new}Whether it is small or notIn i_qminIf yes, let i_qmin＝i_{q2_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 1, go to step S36;

s36, returning to the step S32, repeating the steps S32-S35, and when the recorded current angle beta is set to the same value, taking the value as the optimal value of the current angle beta.

Here, in the whole process, if i_{q_new}Refreshing and saving the current minimum value i when gradually reducing_qmin(ii) a If i_{q_new}And if the angle is not reduced, the value of the beta ChangFLG is changed, so that the searching direction of the beta angle is changed, and the beta angle is kept near the optimal value.

Preferably, in step S4, the limit value i is determined according to the stator current_smaxTo i_qrefLimit value i of stator current when amplitude limiting processing is carried out_smaxAnd signal i_qrefSatisfies the following relationship:

i_qref≤i_smax。

preferably, the pair of signals u of step S5_drefWhen the slicing process is performed, the signal u is made_drefSatisfies the following conditions:

preferably, the pair of signals u of step S5_qrefWhen performing amplitude limiting processing, the signal u is made_qrefSatisfies the following conditions:

wherein u is_dcIs the dc bus voltage of the inverter.

Preferably, step S6 is executed to signal u based on rotor angle θ and current angle β_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefThe expression of (a) is:

where θ represents a rotor angle and β represents a current angle of the entire rotation.

The invention also provides a full-speed area unified control system of the permanent magnet synchronous motor, which comprises the following steps:

the stator current detection module is used for acquiring the stator three-phase current of the permanent magnet synchronous motor in real time;

the position detection module is used for acquiring a rotor angle theta and a real-time rotating speed omega in real time;

a Clark conversion module for Clark conversion of stator three-phase current to obtain current i_αAnd i_β；

An improved Park conversion module for integrally rotating the dq axis coordinate system along the motor rotation direction to obtain d_newq_newRotating the coordinate system, based on the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (1);

a beta optimizing module for optimizing the current angle beta by adjusting the current angle beta when the q-axis feeds back the current i_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

the speed regulator enables the motor to operate at a given rotating speed, meets the requirements of users on the speed of the permanent magnet synchronous motor under different working conditions, and is based on the real-time rotating speed omega and the given rotating speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i_qrefCarrying out amplitude limiting processing;

a current regulator comprising a d-axis current regulator and a q-axis current regulator; wherein the d-axis current regulator gives a signal i_drefFixing to 0; for calculating d-axis current given signal i_drefAnd d-axis feedback current i_dnewPerforming PI control on the deviation, and outputting a signal u_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPerforming PI control on the deviation, and outputting a signal u_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing;

improving a Park inverse transformation module, and optimizing a signal u based on the optimal current angle beta obtained by the rotor angle theta and beta optimizing module_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βref；

A space pulse modulation SVPWM module for adjusting u_αrefAnd u_βrefPerforming spatial pulse modulation to form a PWM signal;

and the inverter circuit controls the rotating speed of the permanent magnet synchronous motor based on the driving of the PWM signal.

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

the invention provides a unified vector control method and a system for a full-speed area of a permanent magnet synchronous motor, which are characterized in that a dq-axis coordinate system is integrally rotated with a current angle beta along the rotation direction of the motor to obtain a new rotation coordinate system, the vector control of the permanent magnet synchronous motor is sequentially carried out on the basis of improved Park transformation, optimization operation of the current angle beta and improved Park inverse transformation, the maximum torque-current ratio control and the low-speed area weak magnetic control in the medium-low speed area can be automatically realized by utilizing the optimization operation of the same current angle beta on the basis of the characteristic that the motor efficiency of a working point closest to the circle center of the coordinate system is close to the highest under the condition that the working points of the medium-low speed area and the high-speed area simultaneously meet the electromagnetic torque equation, the current limit circular equation and the voltage limit elliptical equation of the motor, the unified vector control in the full-speed area can be realized without calculating or detecting the base speed point of the motor or judging whether the motor works in the medium-low-speed area or the high-speed area, the operation stability of the permanent magnet synchronous motor in the mode switching process of different rotating speed areas is ensured.

Drawings

Fig. 1 is a schematic flow chart of a full-speed-range unified vector control method for a permanent magnet synchronous motor according to embodiment 1 of the present invention;

FIG. 2 shows a conventional dq-axis coordinate system and a rotation current angle β as proposed in embodiment 1 of the present inventionFormed of d_newq_newA schematic diagram of a rotating coordinate system;

fig. 3 is a schematic diagram showing a current limit circle, a voltage limit ellipse and a constant electromagnetic torque curve cluster obtained based on an electromagnetic torque equation of a permanent magnet synchronous motor proposed in embodiment 1 of the present invention;

FIG. 4 is a schematic diagram illustrating the optimization of the optimal operating point in the medium/low speed region in embodiment 1 of the present invention;

FIG. 5 is a schematic diagram illustrating the optimization of the optimal operating point of the high speed region in embodiment 1 of the present invention;

fig. 6 is a schematic diagram showing a procedure of an optimizing operation of the current angle β according to embodiment 2 of the present invention;

fig. 7 is a schematic circuit diagram showing a full-speed-range unified vector control system of a permanent magnet synchronous motor according to embodiment 3 of the present invention.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

for better illustration of the present embodiment, certain parts of the drawings may be omitted, enlarged or reduced, and do not represent actual dimensions;

it will be understood by those skilled in the art that certain well-known descriptions of the figures may be omitted.

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent;

example 1

As shown in fig. 1, the present embodiment provides a method for controlling a full-speed area of a permanent magnet synchronous motor uniformly, where the full-speed area includes a medium-low speed area and a high-speed area where the permanent magnet synchronous motor operates, and referring to fig. 1, the method for controlling a full-speed area uniformly includes the following steps: the method comprises the following steps:

s1, obtaining three-phase stator current, a rotor angle theta and a real-time rotating speed omega of the permanent magnet synchronous motor in real time, and performing Clark transformation on the three-phase stator current to obtain current i_αAnd i_β；

S2, integrally rotating the dq axis coordinate system along the rotation direction of the motor with a current angle beta to obtain d_newq_newRotating the coordinate system, based on the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (1);

s3, optimizing the current angle beta, namely adjusting the current angle beta and feeding back current i when the q axis feeds back current_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

s4, setting a given signal of a d-axis regulator of the permanent magnet synchronous motor to be i_drefAnd fixed to 0, and a limit value of the sub-current is set to i_smaxGiven rotation speed of omega_refBased on the real-time rotation speed omega and the given rotation speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i_qrefCarrying out amplitude limiting processing;

s5, calculating a given signal i of the d-axis regulator_drefAnd d-axis feedback current i_dnewPerforming PI control on the deviation, and outputting a signal u_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPI control is performed on the deviation, and a signal u is output_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing;

s6, obtaining the optimal current angle beta based on the rotor angle theta and S3, and comparing the signal u_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefTo u, to u_αrefAnd u_βrefAnd performing space pulse modulation to form a PWM signal, and driving an inverter circuit to control the rotating speed of the permanent magnet synchronous motor by using the PWM signal.

In the present embodiment, the dq axis coordinate system is rotated as a whole at a current angle β in the motor rotation direction as a whole to obtain a new rotation coordinate system d_newq_newThen, permanent magnet synchronous electricity is subjected to inverse Park transformation on the basis of improved Park transformation, optimization operation of a current angle beta and improved Park inverse transformationThe machine carries out vector control, based on the characteristic that the efficiency of the motor at the working point closest to the circle center of a coordinate system is close to the highest under the condition that the working points of the medium-low speed area and the high-speed area simultaneously meet an electromagnetic torque rotating equation, a current limit circular equation and a voltage limit elliptical equation of the motor, the maximum torque-current ratio control of the medium-low speed area and the flux weakening control of the high-speed area are automatically realized by using the set of optimization operation of the current angle beta, the base speed point of the motor does not need to be calculated or detected, the motor does not need to be judged to work in the medium-low speed area or the high-speed area, and the uniform vector control of the full-speed area is realized.

FIG. 2 is a diagram illustrating a conventional dq-axis coordinate system and d formed after rotating a current angle β as set forth in the present embodiment_newq_newA schematic diagram of a rotating coordinate system, wherein in a dq axis coordinate system, a steady-state voltage equation of the permanent magnet synchronous motor is as follows:

the electromagnetic torque equation of the permanent magnet synchronous motor is as follows:

wherein u is_d、u_qThe voltages of a d axis and a q axis of the motor are respectively; i.e. i_d、i_qD-axis current and q-axis current of the motor respectively; r is a stator resistor; l is_d、L_qD-axis and q-axis inductors respectively; omega is the electrical angular velocity, psi, of the motor_mA permanent magnet flux linkage of the motor; p is a radical of_nThe number of pole pairs of the motor is shown.

Maximum current i for sustainable operation of stator windings of d-axis and q-axis current receiving motors_maxSatisfies the current limit circle equation:

d. maximum output voltage u of q-axis voltage inverter_qmaxSatisfies the relation:

wherein u is_dcFor the dc bus voltage of the inverter, the voltage limit elliptic equation is:

the voltage limit elliptic equation is obtained by considering that the voltage drop of the stator resistance in the high-speed area can be ignored relative to the inductive voltage drop of the d axis and the q axis.

A current limit circle, a voltage limit ellipse and a constant electromagnetic torque curve cluster obtained based on an electromagnetic torque equation of the permanent magnet synchronous motor are drawn in a coordinate system with q-axis current as a longitudinal axis and d-axis current as a transverse axis to obtain a graph 3, and the traditional vector control of the permanent magnet synchronous motor is to respectively adopt different control modes to find an optimal working point for a medium-low speed region and a high-speed region in the graph 3.

In the middle and low speed region stage, the q-axis voltage does not reach the limit, so the d-axis current regulator and the q-axis current regulator can be used for independently controlling the d-axis current and the q-axis current, and thus the point on each constant torque curve where the synthesized current is minimum can be found to form a maximum torque current ratio (MTPA) curve, such as the MTPA curve formed by A, B, C points in FIG. 3; in the high-speed stage, if the motor needs to drive T₂The torque load is accelerated to the rotation speed omega₂There are two possible operating points, e.g. D and E in fig. 3, where the resultant current at point D is the minimum, which is the optimal operating point for vector control in the high-speed region; same motor driving T₃If the torque load is to be accelerated to the rotation speed omega₃There are also two possible operating points, G and F in fig. 3, where the resultant current at point G is the smallest, and the optimal operating point is found by the high-speed-region flux weakening control, which is similar to the optimal operating point D, G under various operating conditions.

Therefore, summarizing the characteristics of the optimal operating points A, B, C, D and G, it can be seen that they are the points closest to the center of the circle under the condition that the current limit circle, the voltage limit ellipse and the electromagnetic torque equation are satisfied, and the uniform vector control of the full speed region of the motor can be realized based on the common characteristic.

As shown in FIG. 4, the motor load torque in the middle and low speed region is T₁Rising to speed omega₁Obtaining an optimal working point A through MTPA control, wherein the d-axis current and the q-axis current are i respectively_{d_A}、i_{q_A}Wherein i is_{d_A}Negative, corresponding to a current angle of beta_A. If the d-axis and q-axis current coordinate systems (i) in FIG. 4 are shown_d、i_q) Rotate counterclockwise by an angle beta_AI.e. rotated forward by an angle in the direction of rotation of the motor, a new coordinate system (i) is obtained_{d_new}、i_{q_new}) Then, the current magnitude of the optimal operating point a in the new coordinate system is:

at d_newq_newFinding the optimum working point A in the coordinate system, i.e. at i_{d_new}On the premise of 0, the minimum i is found_{q_new}. Because of d_newq_newIn the coordinate system is in the conventional coordinate system (i)_d、i_q) Rotate counterclockwise by an angle beta_ATherefore, the Park transformation formula and the Park inverse transformation formula are improved.

The improved Park transformation formula is:

the improved Park inverse transformation formula is:

the optimization diagram of the optimal operating point in the high-speed region is shown in FIG. 5, and the motor load torque in the high-speed region is T₂Go up to omega₄The optimal working point D can be obtained by weak magnetic control, and D and q axes are obtained at the timeCurrent is respectively i_{d_D}、i_{q_D}Wherein i is_{d_D}Is a large negative value and corresponds to a current angle of beta_D. D-axis and q-axis current coordinate systems (i) in FIG. 5_d、i_q) Rotate counterclockwise by an angle beta_DObtaining a new coordinate system (i)_{d_new}、i_{q_new}) The current of the optimal working point D in the new coordinate system is as follows:

there is also a need for an improvement to the Park transform formula and the Park inverse transform formula. The improved Park transformation formula is:

the improved Park inverse transformation formula is:

to summarize, i.e., in step S2, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe calculation expression of (a) is:

wherein θ represents the rotor angle, β represents the current angle of the whole rotation, i.e. the modified Park transformation matrix is:

in step S4, the limit value i is determined according to the stator current_smaxTo i_qrefPoles of stator current during amplitude limitingLimit value i_smaxAnd signal i_qrefSatisfies the following relationship:

i_qref≤i_smax。

then, in step S5, the signal u is subjected to_drefWhen the slicing process is performed, the signal u is made_drefSatisfies the following conditions:

for signal u_qrefWhen performing amplitude limiting processing, the signal u is made_qrefSatisfies the following conditions:

wherein u is_dcIs the dc bus voltage of the inverter.

Step S6 on the basis of the rotor angle theta and the current angle beta, the signal u_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefThe expression of (a) is:

where θ represents a rotor angle and β represents a current angle of the entire rotation. The improved Park inverse transform matrix is:

example 2

In this embodiment, β ChangFLG is a direction flag of the current angle β search, β increases when β ChangFLG is 1, and β decreases when β ChangFLG is 0, and the specific optimization process is shown in fig. 6, and the specific process includes:

s31, setting a search mark of a current angle beta as beta ChangFLGThe current angle beta is an initial value beta₀Each time the current angle beta increases or decreases by a step size of delta beta, signal u_drefMaximum value of (1) is u_qmax；

S32, judging whether the real-time rotating speed omega of the motor reaches the given rotating speed omega or not_refSignal u_qrefWhether or not the maximum value u is reached_qmaxIf the given rotation speed is not reached and the signal u_qrefNot reaching the maximum value u_qmaxControlling the current rotating speed of the synchronous motor through a speed regulator; if the motor speed omega reaches the given speed omega_refOr signal u_qrefTo a maximum value u_qmaxIf yes, the current angle β is optimized, and step S33 is executed;

s33, judging whether the beta ChangFLG is 1, if yes, increasing the current angle beta by delta beta, and feeding back current i according to the q axis obtained in the step S2_qnewTo obtain the actual value i of the q-axis feedback current_{q1_new}Step S34 is executed; otherwise, reducing the current angle beta by delta beta to obtain the actual value i of the q-axis feedback current_{q2_new}Step S35 is executed;

s34, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudgment of i_{q1_new}Whether or not less than i_qminIf yes, let i_qmin＝i_{q1_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 0, go to step S36;

s35, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudging the actual value i of the q-axis feedback current_{q2_new}Whether or not less than i_qminIf yes, let i_qmin＝i_{q2_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 1, go to step S36;

s36, returning to the step S32, repeating the steps S32-S35, and when the recorded current angle beta is set to the same value, taking the value as the optimal value of the current angle beta.

In the whole process, if i_{q_new}Refreshing and saving the current minimum value i when gradually reducing_qmin(ii) a If i_{q_new}Changing the value of β changfrg and thus the angle of β without further reductionThe direction is searched, the beta angle is maintained to be close to the optimal value, the base speed point of the motor does not need to be calculated or detected, whether the motor works in a medium-low speed area or a high-speed area does not need to be judged, the maximum torque-current ratio control of the medium-low speed area and the flux weakening control of the high-speed area can be automatically realized through the same set of current angle optimizing criterion in a new coordinate system, and the uniform vector control of the full-speed area is realized.

Example 3

Referring to fig. 7, the present invention also provides a full-speed zone unified control system of a permanent magnet synchronous motor, the system comprising:

the stator current detection module is used for acquiring the stator three-phase current of the permanent magnet synchronous motor in real time;

the position detection module is used for acquiring a rotor angle theta and a real-time rotating speed omega in real time;

the Clark conversion module is used for performing Clark conversion on the three-phase current of the stator to obtain current i_αAnd i_β；

An improved Park conversion module for integrally rotating the dq axis coordinate system along the motor rotation direction to obtain d_newq_newRotating the coordinate system, based on the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (1);

a beta optimizing module for optimizing the current angle beta by adjusting the current angle beta when the q-axis feeds back the current i_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

the speed regulator enables the motor to operate at a given rotating speed, meets the requirements of users on the speed of the permanent magnet synchronous motor under different working conditions, and is based on the real-time rotating speed omega and the given rotating speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i_qrefCarrying out amplitude limiting processing;

a current regulator comprising a d-axis current regulator and a q-axis current regulator; wherein the d-axis current regulator gives a signal i_drefFixing to 0; calculating d-axis current given signal i_drefAnd d-axis feedback current i_dnewPerforming PI control on the deviation, and outputting a signal u_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPI control is performed on the deviation, and a signal u is output_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing; corresponding to PI in fig. 7.

Improving a Park inverse transformation module, and optimizing a signal u based on the optimal current angle beta obtained by the rotor angle theta and beta optimizing module_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd a voltage u_βref；

A space pulse modulation SVPWM module for adjusting u_αrefAnd u_βrefPerforming spatial pulse modulation to form a PWM signal;

and the inverter circuit controls the rotating speed of the permanent magnet synchronous motor based on the drive of the PWM signal.

The full-speed region unified control system can also calculate the given rotating speed omega_refAnd the difference value delta omega of the real-time rotating speed omega of the permanent magnet synchronous motor.

The examples are given solely for the purpose of clearly illustrating the invention and are not intended to limit the practice of the invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (10)

1. A full-speed area unified vector control method of a permanent magnet synchronous motor is characterized in that the full-speed area comprises a medium-low speed area and a high-speed area, and the full-speed area unified vector control method comprises the following steps:

s1, obtaining three-phase stator current, a rotor angle theta and a real-time rotating speed omega of the permanent magnet synchronous motor in real time, and performing Clark transformation on the three-phase stator current to obtain current i_αAnd i_β；

S2, integrally rotating the dq axis coordinate system along the rotation direction of the motor with a current angle beta to obtain d_newq_newRotating the coordinate system, on the basis of the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (1);

s3, optimizing the current angle beta, namely adjusting the current angle beta and feeding back current i when the q axis feeds back current_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

s4, setting a given signal of a d-axis regulator of the permanent magnet synchronous motor to be i_drefAnd fixed to 0, and a limit value of the sub-current is set to i_smaxGiven rotation speed of omega_refBased on the real-time rotation speed omega and the given rotation speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i is to_qrefCarrying out amplitude limiting processing;

s5, calculating a given signal i of the d-axis regulator_drefAnd d-axis feedback current i_dnewPerforming PI control on the deviation, and outputting a signal u_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPerforming PI control on the deviation, and outputting a signal u_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing;

s6, obtaining an optimal current angle beta based on the rotor angle theta and the S3, and comparing the signal u_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefTo u, to u_αrefAnd u_βrefAnd performing space pulse modulation to form a PWM signal, and driving an inverter circuit to control the rotating speed of the permanent magnet synchronous motor by using the PWM signal.

2. The method of claim 1, wherein in the dq axis coordinate system, the steady state voltage equation of the PMSM is:

the electromagnetic torque equation of the permanent magnet synchronous motor is as follows:

wherein u is_d、u_qThe voltages of a d axis and a q axis of the motor are respectively; i.e. i_d、i_qD-axis current and q-axis current of the motor respectively; r is a stator resistor; l is_d、L_qD-axis and q-axis inductors respectively; omega is the electrical angular velocity, psi, of the motor_mA permanent magnet flux linkage of the motor; p is a radical of_nThe number of pole pairs of the motor is shown.

3. The method of claim 2, wherein the d-axis and q-axis currents are controlled by a maximum i current of the motor stator winding capable of continuously running_maxSatisfies the current limit circular equation:

d. maximum output voltage u of q-axis voltage inverter_qmaxSatisfies the relation:

wherein u is_dcFor the dc bus voltage of the inverter, the voltage limit elliptic equation is:

4. the method of claim 1, wherein in step S2, the current i is applied_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe calculation expression of (a) is:

where θ represents a rotor angle and β represents a current angle of the entire rotation.

5. The method of claim 4, wherein the specific procedure of the current angle β optimization operation of step S3 is as follows:

s31, setting a search mark beta of a current angle beta as beta ChangFLG and setting the current angle beta as an initial value beta₀Each time the current angle beta increases or decreases, the step size is delta beta, the signal u_drefMaximum value of (1) is u_qmax；

S32, judging whether the real-time rotating speed omega of the motor reaches the given rotating speed omega or not_refSignal u_qrefWhether or not the maximum value u is reached_qmaxIf the given rotation speed is not reached and the signal u_qrefNot reaching the maximum value u_qmaxControlling the current rotating speed of the synchronous motor through a speed regulator; if the motor speed omega reaches the given speed omega_refOr signal u_qrefTo a maximum value u_qmaxIf yes, the current angle β is optimized, and step S33 is executed;

s33, determining whether β ChangFLG is 1, if yes, increasing the current angle β by Δ β, and obtaining the q-axis feedback current i from step S2_qnewTo obtain the actual value i of the q-axis feedback current_{q1_new}Step S34 is executed; otherwise, reducing the current angle beta by delta beta to obtain the actual value i of the q-axis feedback current_{q2_new}Step S35 is executed;

s34, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudgment ofi_{q1_new}Whether or not less than i_qminIf yes, let i_qmin＝i_{q1_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 0, go to step S36;

s35, setting the minimum value of the q-axis current searched under the current working condition as i_qminJudging the actual value i of the q-axis feedback current_{q2_new}Whether or not less than i_qminIf yes, let i_qmin＝i_{q2_new}Recording the current angle β, and executing step S36; otherwise, let β ChangFLG be 1, go to step S36;

s36, returning to the step S32, repeating the steps S32-S35, and when the recorded current angle beta is set to the same value, taking the value as the optimal value of the current angle beta.

6. The method of claim 5, wherein the stator current limit value i is determined according to the step S4_smaxTo i_qrefLimit value i of stator current when amplitude limiting processing is carried out_smaxAnd signal i_qrefSatisfies the following relationship:

i_qref≤i_smax。

7. the method of claim 6, wherein the pair signal u of step S5 is a full speed region unified vector control method for PMSM_drefWhen the slicing process is performed, the signal u is made_drefSatisfies the following conditions:

8. the method of claim 7, wherein the pair signal u of step S5 is a full-speed-region unified vector control signal_qrefWhen performing amplitude limiting processing, the signal u is made_qrefSatisfies the following conditions:

wherein u is_dcIs the dc bus voltage of the inverter.

9. The method of claim 8, wherein the step S6 is performed on the signal u based on the rotor angle θ and the current angle β_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βrefThe expression of (a) is:

where θ represents a rotor angle and β represents a current angle of the entire rotation.

10. A full-speed zone unified control system of a permanent magnet synchronous motor, the full-speed zone unified control system comprising:

the stator current detection module is used for acquiring the stator three-phase current of the permanent magnet synchronous motor in real time;

the position detection module is used for acquiring a rotor angle theta and a real-time rotating speed omega in real time;

the Clark conversion module is used for performing Clark conversion on the three-phase current of the stator to obtain current i_αAnd i_β；

An improved Park conversion module for integrally rotating the dq axis coordinate system along the motor rotation direction to obtain d_newq_newRotating the coordinate system, based on the rotor angle theta and the current angle beta, for the current i_αAnd i_βCarrying out improved Park conversion to obtain d-axis feedback current i_dnewAnd q-axis feedback current i_qnewThe computational expression of (1);

a beta optimizing module for optimizing the current angle beta by adjusting the current angle beta when the q-axis feeds back the current i_qnewWhen the current angle beta is minimum, the current angle beta is an optimal value;

the speed regulator enables the motor to operate at a given rotating speed, meets the requirements of users on the speed of the permanent magnet synchronous motor under different working conditions, and is based on the real-time rotating speed omega and the given rotating speed omega_refObtaining a given signal i of the q-axis regulator_qrefAccording to the limit value i of the stator current_smaxTo i_qrefCarrying out amplitude limiting processing;

a current regulator comprising a d-axis current regulator and a q-axis current regulator; wherein the d-axis current regulator gives a signal i_drefFixing to 0; d-axis current set signal i_drefAnd d-axis feedback current i_dnewPI control is performed on the deviation, and a signal u is output_drefAnd to the signal u_drefCarrying out amplitude limiting processing; calculating q-axis current given signal i_qrefWith q-axis feedback current i_qnewPerforming PI control on the deviation, and outputting a signal u_qrefAnd to the signal u_qrefCarrying out amplitude limiting processing;

improving a Park inverse transformation module, and optimizing a signal u based on the optimal current angle beta obtained by the rotor angle theta and beta optimizing module_qrefAnd signal u_qrefCarrying out improved Park inverse transformation to obtain a voltage u_αrefAnd voltage u_βref；

A space pulse modulation SVPWM module for adjusting u_αrefAnd u_βrefPerforming space pulse modulation to form a PWM signal;

and the inverter circuit controls the rotating speed of the permanent magnet synchronous motor based on the driving of the PWM signal.

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