阅读说明：本技术 永磁同步电机的控制方法、系统、介质及终端 (Control method, system, medium and terminal of permanent magnet synchronous motor ) 是由 马少才 黄继慢 陈文峰 于 2020-05-29 设计创作，主要内容包括：本发明提供一种永磁同步电机的控制方法、系统、介质及终端；所述方法包括以下步骤：将永磁同步电机的预设转速与实时转速做差,并将差值输入至PI调节器；确定实时三相电压对应电压矢量的幅角及电压矢量所在的扇区；计算得到瞬时有功功率实际值和瞬时无功功率实际值；建立优化开关矢量表；从优化开关矢量表中选择相应的电压矢量组,并根据电压矢量组获取控制信号,以实现控制功能；本发明可直接从开关矢量表中选择合适的空间电压矢量实现对瞬时功率直接控制,进而达到调速的目的,在有功功率稳态波动得到显著减小的同时,无功功率的稳态波动也得到明显地抑制,进而转矩稳态波动也得到抑制,系统的控制性能得以改善,达到节能的目的。(The invention provides a control method, a system, a medium and a terminal of a permanent magnet synchronous motor; the method comprises the following steps: the method comprises the following steps of (1) making a difference between a preset rotating speed and a real-time rotating speed of the permanent magnet synchronous motor, and inputting the difference to a PI regulator; determining the amplitude of a voltage vector corresponding to the real-time three-phase voltage and a sector where the voltage vector is located; calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value; establishing an optimized switch vector table; selecting a corresponding voltage vector group from the optimized switch vector table, and acquiring a control signal according to the voltage vector group to realize a control function; the invention can directly select proper space voltage vector from the switch vector table to realize the direct control of instantaneous power, thereby achieving the purpose of speed regulation, obviously inhibiting the steady-state fluctuation of reactive power while obviously reducing the steady-state fluctuation of active power, further inhibiting the steady-state fluctuation of torque, improving the control performance of the system and achieving the purpose of energy conservation.)

1. A control method of a permanent magnet synchronous motor is characterized by comprising the following steps:

acquiring the real-time rotating speed of a permanent magnet synchronous motor and the real-time three-phase voltage and the real-time three-phase current of the permanent magnet synchronous motor under a two-phase static coordinate system;

the difference value is obtained between the preset rotating speed of the permanent magnet synchronous motor and the real-time rotating speed, the difference value is input into a PI regulator, and the output of the PI regulator is used as the instantaneous active power preset value; recording the preset value of the instantaneous reactive power as zero;

determining the argument of a voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage, and determining a sector where the voltage vector is located according to the argument;

calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current;

establishing an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector;

and selecting a corresponding voltage vector group from the optimized switch vector table, and acquiring a control signal according to the voltage vector group to realize a control function.

2. The method of claim 1, wherein obtaining the real-time rotational speed of the PMSM comprises:

establishing a voltage equation and a back electromotive force equation of the permanent magnet synchronous motor under the two-phase static coordinate system;

the voltage equation is:

the back electromotive force equation is:

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system respectively_α、e_βThe components of the back electromotive force on the α axis and the β axis of the two-phase stationary coordinate system, respectively, R_sIs a stator phase resistance; l is_sIs a stator phase inductance; k is a radical of_eIs the back electromotive force coefficient; omega_rIs the rotor electrical angular velocity; theta_rIs the rotor position angle;

acquiring a current equation according to the voltage equation;

the current equation is:

defining a sliding mode surface;

the slip form surface is:

wherein the content of the first and second substances,the components of the estimated three-phase current on the α axis and the β axis of the two-phase stationary coordinate system, respectively, and x represents a state variableS_αβ(x) Representing the operation of two-row and one-column matrixes on the state variable x under a two-phase static coordinate system; s represents a slip form surface;

constructing a sliding-mode observer according to the current equation;

the sliding-mode observer is as follows:

wherein k is a sliding mode gain coefficient; sigmoid function ofWherein a is a constant greater than zero;

calculating the real-time rotating speed according to the back electromotive force equation;

the calculation formula is as follows:

wherein the content of the first and second substances,components of the back electromotive force estimated for the sliding mode observer on the α axis and the β axis of the two-phase stationary coordinate system, respectively;representing an estimated rotor position angle calculated from the back electromotive force estimated by the sliding mode observer; ω represents the real-time rotational speed.

3. The control method of the permanent magnet synchronous motor according to claim 1, wherein the argument of the voltage vector corresponding to the real-time three-phase voltage is determined according to the real-time three-phase voltage, and the calculation formula is as follows:

wherein θ represents the argument; u. of_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase stationary coordinate system, respectively.

4. The control method of the permanent magnet synchronous motor according to claim 1, wherein an instantaneous active power actual value and an instantaneous reactive power actual value are calculated according to the real-time three-phase voltage and the real-time three-phase current, and the calculation formula is as follows:

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system are respectively, p represents the actual value of the instantaneous active power, and q represents the actual value of the instantaneous reactive power.

5. The control method of a permanent magnet synchronous motor according to claim 1, wherein the step of establishing an optimized switching vector table based on the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector comprises the steps of:

comparing the instantaneous active power preset value with the instantaneous active power actual value to obtain the active power change rate;

comparing the instantaneous reactive power preset value with the instantaneous reactive power actual value to obtain the reactive power change rate;

and establishing the optimized switching vector table according to the active power change rate and the reactive power change rate corresponding to the voltage vectors in different sectors and a preset switching vector table.

6. The control method of the permanent magnet synchronous motor according to claim 1, wherein selecting a corresponding voltage vector group from the optimized switching vector table and obtaining a control signal according to the voltage vector group to realize a control function comprises the steps of:

calculating the action time of the corresponding voltage vector in the voltage vector group, wherein the calculation formula is as follows:

wherein the voltage vector group comprises two effective working vectors and a zero vector; p is a radical of^k+1、q^k+1Respectively representing the actual value of the instantaneous active power and the actual value of the instantaneous reactive power at the moment of k + 1; p is a radical of^k、q^kRespectively representing the actual value of the instantaneous active power and the actual value of the instantaneous reactive power at the moment k; p is a radical of^ref、q^refRespectively representing instantaneous active power reference value and instantaneous reactive power reference value, let p^k+1＝p^ref，q^k+1＝q^ref；f_p1、f_p2、f_p0Respectively representing active power change rates corresponding to two effective working vectors and a zero vector at the moment k; f. of_q1、f_q2、f_q0Respectively representing the reactive power change rates corresponding to two effective working vectors and a zero vector at the moment k; t is t₁、t₂、t₀Respectively representing the action time of two effective working vectors and a zero vector; t is t_scRepresenting a control cycle;

and converting the action time into the control signal through PWM to realize a control function.

7. The control method of a permanent magnet synchronous motor according to claim 6, wherein when the sum of the action times of two effective working vectors is greater than one control period in one switching period, the calculation formula of the action times of the two effective working vectors and the zero vector is:

wherein, t₁'、t₂'、t₀' respectively indicates that in a switching period, when the sum of action time of two effective working vectors is more than a control period, two effective working vectorsThe action time of the working vector and said zero vector.

8. A control system of a permanent magnet synchronous motor, comprising: the device comprises an acquisition module, an output module, a determination module, a calculation module, an establishment module and a control module;

the acquisition module is used for acquiring the real-time rotating speed of the permanent magnet synchronous motor and the real-time three-phase voltage and the real-time three-phase current of the permanent magnet synchronous motor under a two-phase static coordinate system;

the output module is used for making a difference between the preset rotating speed of the permanent magnet synchronous motor and the real-time rotating speed, inputting the difference value into the PI regulator, and taking the output of the PI regulator as an instantaneous active power preset value; recording the preset value of the instantaneous reactive power as zero;

the determining module is used for determining the argument of a voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage and determining a sector where the voltage vector is located according to the argument;

the calculation module is used for calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current;

the establishing module is used for establishing an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector;

and the control module is used for selecting a corresponding voltage vector group from the optimized switch vector table and acquiring a control signal according to the voltage vector group so as to realize a control function.

9. A storage medium on which a computer program is stored, characterized in that the computer program, when executed by a processor, implements the control method of a permanent magnet synchronous machine according to any one of claims 1 to 7.

10. A terminal, comprising: a processor and a memory;

the memory is used for storing a computer program;

the processor is configured to execute the computer program stored in the memory to cause the terminal to execute the control method of the permanent magnet synchronous motor according to any one of claims 1 to 7.

Technical Field

The invention belongs to the field of motor control, and particularly relates to a control method, a control system, a control medium and a control terminal of a permanent magnet synchronous motor.

Background

The permanent magnet synchronous motor is a synchronous motor which generates a synchronous rotating magnetic field by permanent magnet excitation, the permanent magnet is used as a rotor to generate a rotating magnetic field, and a three-phase stator winding is reacted through an armature under the action of the rotating magnetic field to induce three-phase symmetrical current; when the kinetic energy of the rotor is converted into electric energy, the permanent magnet synchronous motor is used as a generator; in addition, when three-phase symmetrical current is introduced to the stator side, the three-phase stator current generates a rotating magnetic field in the space due to the fact that the phase difference of the three-phase stator is 120 in the space position, the rotor rotates under the action of electromagnetic force to move, electric energy is converted into kinetic energy at the moment, and the permanent magnet synchronous motor serves as a motor.

The permanent magnet synchronous motor has the advantages of higher torque density, power density, high efficiency, wide speed regulation range and low noise, and is widely applied to the fields of transportation, compressors, wind power generation and the like, and the high-performance control scheme mainly comprises direct torque control and vector control; the direct torque control strategy has the advantages of simple control structure, no complex coordinate transformation, good robustness, small motor parameter dependence and the like, but because the direct torque control strategy takes rapidity as a main target, the stator flux linkage is often controlled to be constant, so that the stator flux linkage is too large at low load, the energy conservation is not facilitated, and the input power factor is also low; the vector control is a control method based on grid voltage directional space voltage vector synthesis, the clack transformation (i.e. the three-phase currents of a, b and c of a stator are projected under a static alpha beta two-phase coordinate system), Park's coordinate transformation (Park's transformation, which is the most commonly used coordinate transformation for analyzing the operation of the synchronous motor at present, Park's transformation projects the three-phase currents of a stator to a direct axis (d axis) rotating along with a rotor, an orthogonal axis (q axis) and a zero axis (0 axis) perpendicular to a dq plane, thereby realizing the diagonalization of a stator inductance matrix, namely the transformation of an abc coordinate system to a dq coordinate system, the inverse transformation of a Park coordinate (the inverse operation of the Park's transformation), a plurality of PI regulators and a complex modulation strategy, most of a plurality of loads are in steady-state operation, and the system has low dynamic performance, and has a great demand for energy conservation in steady-state operation; at present, energy conservation is the main national policy in China, and the research of a control method which has the advantages of simple control, simple and convenient calculation and energy conservation like the direct torque control is very important.

Disclosure of Invention

In view of the above drawbacks of the prior art, an object of the present invention is to provide a method, a system, a medium, and a terminal for controlling a permanent magnet synchronous motor, which are used to solve the problems of complicated operation and energy consumption in controlling the permanent magnet synchronous motor in the prior art.

In order to achieve the above and other related objects, the present invention provides a method for controlling a permanent magnet synchronous motor, comprising the steps of: acquiring the real-time rotating speed of a permanent magnet synchronous motor and the real-time three-phase voltage and the real-time three-phase current of the permanent magnet synchronous motor under a two-phase static coordinate system; the difference value is obtained between the preset rotating speed of the permanent magnet synchronous motor and the real-time rotating speed, the difference value is input into a PI regulator, and the output of the PI regulator is used as the instantaneous active power preset value; recording the preset value of the instantaneous reactive power as zero; determining the argument of a voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage, and determining a sector where the voltage vector is located according to the argument; calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current; establishing an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector; and selecting a corresponding voltage vector group from the optimized switch vector table, and acquiring a control signal according to the voltage vector group to realize a control function.

In an embodiment of the present invention, the obtaining the real-time rotation speed of the permanent magnet synchronous motor includes the following steps: establishing a voltage equation and a back electromotive force equation of the permanent magnet synchronous motor under the two-phase static coordinate system; the voltage equation is:

the back electromotive force equation is:

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system respectively_α、e_βThe components of the back electromotive force on the α axis and the β axis of the two-phase stationary coordinate system, respectively, R_sIs a stator phase resistance; l is_sIs a stator phase inductance; k is a radical of_eIs the back electromotive force coefficient; omega_rIs the rotor electrical angular velocity; theta_rIs the rotor position angle;

acquiring a current equation according to the voltage equation; the current equation is:

defining a sliding mode surface; the slip form surface is:

wherein the content of the first and second substances,the components of the estimated three-phase current on the α axis and the β axis of the two-phase stationary coordinate system, respectively, and x represents a state variableRepresenting the operation of two-row and one-column matrixes on the state variable x under a two-phase static coordinate system; s represents a slip form surface;

constructing a sliding-mode observer according to the current equation; the sliding-mode observer is as follows:

wherein k is a sliding mode gain coefficient; sigmoid function ofWherein a is a constant greater than zero;

calculating the real-time rotating speed according to the back electromotive force equation; the calculation formula is as follows:

wherein the content of the first and second substances,components of the back electromotive force estimated for the sliding mode observer on the α axis and the β axis of the two-phase stationary coordinate system, respectively;representing an estimated rotor position angle calculated from the back electromotive force estimated by the sliding mode observer; ω represents the real-time rotational speed.

In an embodiment of the present invention, the argument of the voltage vector corresponding to the real-time three-phase voltage is determined according to the real-time three-phase voltage, and a calculation formula is as follows:

wherein θ represents the argument; u. of_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase stationary coordinate system, respectively.

In an embodiment of the present invention, an instantaneous active power actual value and an instantaneous reactive power actual value are obtained by calculation according to the real-time three-phase voltage and the real-time three-phase current, and a calculation formula is as follows:

p＝1.5(u_βi_β+u_αi_α)

q＝1.5(u_βi_α-u_αi_β)；

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system are respectively, p represents the actual value of the instantaneous active power, and q represents the actual value of the instantaneous reactive power.

In an embodiment of the present invention, the establishing an optimized switching vector table according to the preset instantaneous active power value, the preset instantaneous reactive power value, the actual instantaneous active power value, the actual instantaneous reactive power value and the sector includes the following steps: comparing the instantaneous active power preset value with the instantaneous active power actual value to obtain the active power change rate; comparing the instantaneous reactive power preset value with the instantaneous reactive power actual value to obtain the reactive power change rate; and establishing the optimized switching vector table according to the active power change rate and the reactive power change rate corresponding to the voltage vectors in different sectors and a preset switching vector table.

In an embodiment of the present invention, selecting a corresponding voltage vector group from the optimized switching vector table, and obtaining a control signal according to the voltage vector group to implement a control function includes the following steps: calculating the action time of the corresponding voltage vector in the voltage vector group, wherein the calculation formula is as follows:

wherein the voltage vector group comprises two effective working vectors and a zero vector; p is a radical of^k+1、q^k+1Respectively representing the actual value of the instantaneous active power and the actual value of the instantaneous reactive power at the moment of k + 1; p is a radical of^k、q^kRespectively representing the actual value of the instantaneous active power and the actual value of the instantaneous reactive power at the moment k; p is a radical of^ref、q^refRespectively representing instantaneous active power reference value and instantaneous reactive power reference value, let p^k+1＝p^ref，q^k+1＝q^ref；f_p1、f_p2、f_p0Respectively representing active power change rates corresponding to two effective working vectors and a zero vector at the moment k; f. of_q1、f_q2、f_q0Respectively representing the reactive power change rates corresponding to two effective working vectors and a zero vector at the moment k; t is t₁、t₂、t₀Respectively representing the action time of two effective working vectors and a zero vector; t is t_scRepresenting a control cycle;

and converting the action time into the control signal through PWM to realize a control function.

In an embodiment of the present invention, when the sum of the action times of the two effective working vectors is greater than one control cycle in one switching cycle, the calculation formula of the action times of the two effective working vectors and the zero vector is:

wherein, t₁'、t₂'、t₀' respectively indicates the action time of two effective working vectors and the action time of a zero vector when the sum of the action time of the two effective working vectors is larger than one control period in one switching period.

The invention provides a control system of a permanent magnet synchronous motor, which comprises: the device comprises an acquisition module, an output module, a determination module, a calculation module, an establishment module and a control module; the acquisition module is used for acquiring the real-time rotating speed of the permanent magnet synchronous motor and the real-time three-phase voltage and the real-time three-phase current of the permanent magnet synchronous motor under a two-phase static coordinate system; the output module is used for making a difference between the preset rotating speed of the permanent magnet synchronous motor and the real-time rotating speed, inputting the difference value into the PI regulator, and taking the output of the PI regulator as an instantaneous active power preset value; recording the preset value of the instantaneous reactive power as zero; the determining module is used for determining the argument of a voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage and determining a sector where the voltage vector is located according to the argument; the calculation module is used for calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current; the establishing module is used for establishing an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector; and the control module is used for selecting a corresponding voltage vector group from the optimized switch vector table and acquiring a control signal according to the voltage vector group so as to realize a control function.

The present invention provides a storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described control method of a permanent magnet synchronous motor.

The present invention provides a terminal, including: a processor and a memory; the memory is used for storing a computer program; the processor is used for executing the computer program stored in the memory so as to enable the terminal to execute the control method of the permanent magnet synchronous motor.

As described above, the control method, system, medium and terminal of the permanent magnet synchronous motor according to the present invention have the following advantages:

(1) the invention adopts a direct power control mode to realize the control of the permanent magnet synchronous motor, not only has a simple control form like the traditional direct torque control, but also can lead the reactive power control of the input motor to be close to zero, thereby achieving the aim of unit power factor operation, greatly improving the operation performance of the permanent magnet synchronous motor and improving the operation efficiency;

(2) compared with the traditional control method adopting space voltage vector synthesis, the method does not need park coordinate transformation and park coordinate inverse transformation, and can directly select proper space voltage vectors from a switch vector table according to the requirements of active power and reactive power change to realize the direct control of instantaneous power so as to achieve the aim of speed regulation;

(3) the invention aims to simultaneously inhibit the problem pulsation of active power and reactive power, obviously inhibit the steady-state fluctuation of the reactive power while obviously reducing the steady-state fluctuation of the active power, further inhibit the steady-state fluctuation of torque, improve the control performance of a system and achieve the aim of saving energy.

Drawings

Fig. 1 is a flowchart illustrating a control method of a permanent magnet synchronous motor according to an embodiment of the present invention.

Fig. 2 is a flowchart illustrating an embodiment of the present invention for obtaining a real-time rotation speed of a pmsm.

Fig. 3 shows a flow chart of the present invention for establishing an optimized switching vector table in one embodiment.

Fig. 4 is a schematic diagram illustrating the effect of different voltage vectors on active power in different sectors according to an embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating the effect of different voltage vectors on reactive power in different sectors according to an embodiment of the present invention.

FIG. 6 is a flow chart illustrating obtaining control signals according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a control system of a permanent magnet synchronous motor according to an embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a terminal according to an embodiment of the invention.

Fig. 9 is a block diagram illustrating the operation of the method for controlling a permanent magnet synchronous motor according to an embodiment of the present invention.

Fig. 10 is a waveform diagram of the instantaneous active power input to the stator winding according to an embodiment of the present invention.

Fig. 11 is a waveform diagram of the reactive power of the present invention in one embodiment.

FIG. 12 is a waveform diagram of three-phase current in one embodiment of the present invention.

FIG. 13 is a waveform illustrating the torque of the present invention in one embodiment.

FIG. 14 is a waveform illustrating the rotation speed of the motor according to an embodiment of the present invention.

Description of the reference symbols

71 acquisition module

72 output module

73 determination module

74 calculation module

75 building block

76 control module

81 processor

82 memory

S1-S6

S11-S15

S51-S53

S61-S62

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

The control method, the system, the medium and the terminal of the permanent magnet synchronous motor realize the control of the permanent magnet synchronous motor by adopting a direct power control mode, have a simple control form like the traditional direct torque control, and can enable the reactive power control of the input motor to be close to zero, thereby achieving the aim of unit power factor operation, greatly improving the operation performance of the permanent magnet synchronous motor and improving the operation efficiency; compared with the traditional control method adopting space voltage vector synthesis, the method does not need park coordinate transformation and park coordinate inverse transformation, and can directly select proper space voltage vectors from a switch vector table according to the requirements of active power and reactive power change to realize the direct control of instantaneous power so as to achieve the aim of speed regulation; the invention aims to simultaneously inhibit the problem pulsation of active power and reactive power, obviously inhibit the steady-state fluctuation of the reactive power while obviously reducing the steady-state fluctuation of the active power, further inhibit the steady-state fluctuation of torque, improve the control performance of a system and achieve the aim of saving energy.

As shown in fig. 1, in an embodiment, the method for controlling a permanent magnet synchronous motor of the present invention includes the following steps:

and step S1, acquiring the real-time rotating speed of the permanent magnet synchronous motor and the real-time three-phase voltage and the real-time three-phase current of the permanent magnet synchronous motor under the two-phase static coordinate system.

As shown in fig. 2, in an embodiment, the obtaining of the real-time rotation speed of the permanent magnet synchronous motor includes the following steps:

and step S11, establishing a voltage equation and a back electromotive force equation of the permanent magnet synchronous motor under the two-phase static coordinate system.

It should be noted that, neglecting iron core saturation, disregarding hysteresis and eddy current loss, setting the permanent magnet conductivity of the permanent magnet synchronous motor to be zero, and establishing a voltage equation and a back electromotive force equation of the permanent magnet synchronous motor in a two-phase static coordinate system.

Specifically, the voltage equation is:

the back electromotive force equation is:

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system respectively_α、e_βThe components of the back electromotive force on the α axis and the β axis of the two-phase stationary coordinate system, respectively, R_sIs a stator phase resistance; l is_sIs a stator phase inductance; k is a radical of_eIs the back electromotive force coefficient; omega_rIs the rotor electrical angular velocity; theta_rIs the rotor position angle.

And step S12, acquiring a current equation according to the voltage equation.

In order to observe the back electromotive force by using a sliding-mode observer, the voltage equation in step S11 is rewritten into a state equation of current.

Specifically, the current equation is:

and step S13, defining a sliding mode surface.

Specifically, according to the sliding mode control theory, a sliding mode surface is defined, and the sliding mode surface is:

wherein the content of the first and second substances,the components of the estimated three-phase current on the α axis and the β axis of the two-phase stationary coordinate system, respectively, and x represents a state variableRepresenting the operation of two-row and one-column matrixes on the state variable x under a two-phase static coordinate system; s denotes a slip form face.

It should be noted that Sliding Mode Control (SMC) is also called variable structure control, and is essentially a special type of nonlinear control, and the nonlinearity is represented as discontinuity of the control, and this control strategy is different from other controls in that the "structure" of the system is not fixed, but can be changed continuously and purposefully according to the current state of the system (such as deviation and its derivatives) in a dynamic process, so as to force the system to move according to the state trajectory of a predetermined "sliding mode".

And step S14, constructing a sliding mode observer according to the current equation.

Specifically, according to the current equation in step S12, a sliding-mode observer is constructed, where the sliding-mode observer is:

wherein k is a sliding mode gain coefficient; sigmoid function ofWherein a is a constant greater than zero;

and step S15, calculating the real-time rotating speed according to the back electromotive force equation.

Specifically, the calculation formula is:

wherein the content of the first and second substances,components of the back electromotive force estimated for the sliding mode observer on the α axis and the β axis of the two-phase stationary coordinate system, respectively;representing an estimated rotor position angle calculated from the back electromotive force estimated by the sliding mode observer; ω represents the real-time rotational speed.

Step S2, making a difference between the preset rotating speed of the permanent magnet synchronous motor and the real-time rotating speed, inputting the difference value into a PI regulator, and taking the output of the PI regulator as the instantaneous active power preset value; the instantaneous reactive power preset value is recorded as zero.

Specifically, the difference is made between the real-time rotating speed obtained in step S1 and the preset rotating speed, and then the difference is input into the PI regulator, and the output of the PI regulator is used as the instantaneous active power preset value.

Further, to maintain unity power factor operation, the instantaneous reactive power preset value is recorded as zero.

And step S3, determining the argument of the voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage, and determining the sector where the voltage vector is located according to the argument.

The sector is formed by dividing a plane 360 ° into 6 regions on average, and 0 ° -60 °, 60 ° -120 °, 120 ° -180 ° -240 °, 240 ° -360 ° correspond to one sector respectively, and after the amplitude angle of the voltage vector is determined, the sector in which the voltage vector is located can be directly determined according to the amplitude angle.

In an embodiment, the argument of the voltage vector corresponding to the real-time three-phase voltage is determined according to the real-time three-phase voltage, and the calculation formula is as follows:

wherein θ represents the argument; u. of_α、u_βRespectively real-time three-phase voltage is static at two phasesThe α and β axes of the coordinate system.

And step S4, calculating to obtain an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current.

Specifically, based on the instantaneous power theory, an instantaneous active power actual value and an instantaneous reactive power actual value are calculated and obtained on the premise that the real-time three-phase voltage and the real-time three-phase current are known.

In an embodiment, an instantaneous active power actual value and an instantaneous reactive power actual value are obtained by calculation according to the real-time three-phase voltage and the real-time three-phase current, and the calculation formula is as follows:

p＝1.5(u_βi_β+u_αi_α)

q＝1.5(u_βi_α-u_αi_β)；

wherein i_α、i_βThe components of the real-time three-phase current on the α axis and the β axis of the two-phase static coordinate system, u_α、u_βThe components of the real-time three-phase voltage on the α axis and the β axis of the two-phase static coordinate system are respectively, p represents the actual value of the instantaneous active power, and q represents the actual value of the instantaneous reactive power.

And step S5, establishing an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value and the sector.

As shown in fig. 3, in an embodiment, the creating an optimized switching vector table according to the preset instantaneous active power value, the preset instantaneous reactive power value, the actual instantaneous active power value, the actual instantaneous reactive power value, and the sector includes the following steps:

and step S51, comparing the instantaneous active power preset value with the instantaneous active power actual value to obtain the active power change rate.

And step S52, comparing the instantaneous reactive power preset value with the instantaneous reactive power actual value to obtain the reactive power change rate.

Step S53, establishing the optimized switching vector table according to the active power change rate and the reactive power change rate corresponding to the voltage vectors in different sectors and a preset switching vector table.

It should be noted that, in the two-phase stationary coordinate system, the three-phase voltage vector includes 8 cases, as shown in table 1 below.

TABLE 1 table of 8 voltage vector values under two-phase stationary coordinate system

As shown in fig. 4 and 5, the active power change rate and the reactive power change rate under different voltage vectors in table 1 can be obtained according to step S51 and step S52.

Further, the table of preset switching vectors is shown in table 2 below.

TABLE 2 Preset switch vector table

Sector area	p increase q increase	p increases and q decreases	Decrease in p by increase in q	Reduction of p by q
					0°～60°	V0，V4	V0，V6	V2，V0	V1，V0
60°～120°	V0，V5	V1，V0	V3，V0	V2，V0
					120°～180°	V0，V6	V0，V2	V4，V0	V3，V0
180°～240°	V1，V0	V0，V3	V5，V0	V4，V0
					240°～300°	V0，V2	V0，V4	V6，V0	V5，V0
300°～360°	V0，V3	V0，V5	V1，V0	V6，V0

It should be noted that, in the preset switching vector table, an effective working vector and a zero vector are selected from the vector table according to the changes of active power and reactive power in a control period, but in the method, the action time of each voltage vector is calculated only according to the reference value of the active power, the steady state fluctuation of the active power is improved, and further the torque fluctuation is improved, but the reactive power fluctuation is large, and particularly in a high-power occasion, the control performance of the system is influenced.

From fig. 4 and 5, the effect of different voltage vectors on the rate of change of active power and the rate of change of reactive power in different sectors can be seen; specifically, in each sector, two effective working vectors corresponding to four variation trends, namely active power and reactive power increase, active power increase and reactive power decrease, active power decrease and reactive power increase, active power and reactive power decrease, are provided instead of one, namely, a combination of two effective working vectors and a zero vector can be obtained in each different sector according to different power changes, and then 24 groups of vector combinations can be obtained in an interval of 0-360 degrees of three-phase voltage of the stator.

Specifically, an optimized switching vector table is established according to the variation trend of the active power and the reactive power under the action of different voltage vectors in different sectors in fig. 4 and 5, as shown in table 3 below.

TABLE 3 optimized switching vector table

It should be noted that, when the direct power control method of optimizing the switching vector table is adopted, the steady-state fluctuation of the active power is obviously reduced, and the steady-state fluctuation of the reactive power is also obviously suppressed, so that the steady-state fluctuation of the torque is also suppressed, and the performance of the system is improved.

And step S6, selecting a corresponding voltage vector group from the optimized switching vector table, and acquiring a control signal according to the voltage vector group to realize a control function.

As shown in fig. 6, in an embodiment, selecting a corresponding voltage vector group from the optimized switching vector table, and obtaining a control signal according to the voltage vector group to implement a control function includes the following steps:

and step S61, calculating the acting time of the corresponding voltage vector in the voltage vector group.

Specifically, a voltage vector group is selected from an optimization switch vector table according to a sector where the voltage vector is located and the change trend of the required power, the voltage vector group comprises two effective working vectors and a zero vector, the action time of the two effective working vectors and the action time of the zero vector are calculated, and the calculation formula is as follows:

wherein the voltage vector group comprises two effective working vectors and a zero vector; p is a radical of^k+1、q^k+1Respectively representing the actual value of the instantaneous active power and the actual value of the instantaneous reactive power at the moment of k + 1; p is a radical of^k、q^kRespectively representing instantaneous active power at time kActual value of rate and actual value of instantaneous reactive power; p is a radical of^ref、q^refRespectively representing instantaneous active power reference value and instantaneous reactive power reference value, let p^k+1＝p^ref，q^k+1＝q^ref；f_p1、f_p2、f_p0Respectively representing active power change rates corresponding to two effective working vectors and a zero vector at the moment k; f. of_q1、f_q2、f_q0Respectively representing the reactive power change rates corresponding to two effective working vectors and a zero vector at the moment k; t is t₁、t₂、t₀Respectively representing the action time of two effective working vectors and a zero vector; t is t_scRepresenting a control cycle.

Further, in order to reduce the switching loss and improve the system operation efficiency, the calculation formula of the action time is improved as follows on the principle of reducing the switching times:

in one embodiment, when the sum of the action times of the two effective working vectors is greater than one control cycle in one switching cycle, the calculation formula of the action times of the two effective working vectors and the zero vector is as follows:

wherein, t₁'、t₂'、t₀' respectively indicates the action time of two effective working vectors and the action time of a zero vector when the sum of the action time of the two effective working vectors is larger than one control period in one switching period.

It should be noted that, the variable subscript bands 0 are all corresponding zero vectors; while subscript bands 1 and 2 correspond to two valid working vectors, respectively.

And step S62, converting the action time into the control signal through PWM modulation so as to realize a control function.

The control method of the permanent magnet synchronous motor of the present invention is further verified by the following specific examples.

As shown in fig. 9, in an embodiment, the control method of the permanent magnet synchronous motor is applied to the structure shown in fig. 9 (i.e. the control method of the permanent magnet synchronous motor according to the present invention is implemented depending on the structure in fig. 9), and specifically includes a permanent magnet synchronous motor, an inverter switching tube, a PI regulator, a sliding mode observer, and an optimized switching vector table; the sliding mode observer is used for calculating the real-time rotating speed of the permanent magnet synchronous motor; the PI regulator is used for receiving a difference value between a preset rotating speed and a real-time rotating speed and generating an instantaneous active power preset value; and selecting a voltage vector from the optimized switching vector table, calculating the action time of the voltage vector, and finally converting the action time into a control signal through PWM (pulse width modulation) so as to realize that the control signal controls a switching tube of the inverter.

Specifically, the preset rotation speed n^*Making a difference with the real-time rotating speed n, and taking the difference value as an inner loop instantaneous active power preset value p through the output of a PI regulator^*(ii) a Instantaneous reactive power preset value q for keeping unit power factor operation^*0, determining amplitude angle theta of voltage vector according to sampled three-phase voltage, determining sector according to amplitude angle theta, and comparing αβ voltage u under two-phase static coordinate system_α、u_βAnd current i_α、i_βPerforming power calculation to obtain an instantaneous active power actual value p and an instantaneous reactive power actual value q; presetting the instantaneous active power p^*Instantaneous reactive power preset value q^*Comparing the instantaneous active power actual value p and the instantaneous reactive power actual value q to obtain the variation trend of the active power and the reactive power; and according to the influence of each voltage vector of the sector on the change rate of active power and reactive power, selecting an optimized voltage vector from an optimized switching vector table, calculating the action time of the voltage vector, and finally converting the action time into a control signal through PWM (pulse width modulation) for driving an inverter switching tube.

As shown in fig. 10 to 13, when the permanent magnet synchronous motor is accelerated, the permanent magnet synchronous motor is accelerated at the maximum torque allowed, and the instantaneous active power input by the stator winding linearly increases along with the rotating speed; when the speed is stable, the active power and the torque are basically kept stable, and the reactive power can be controlled to be close to zero, thereby indicating the effectiveness of the reactive power.

As shown in fig. 14, the rotational speed of the permanent magnet synchronous motor is kept stable during operation.

It should be noted that the protection scope of the control method of the permanent magnet synchronous motor according to the present invention is not limited to the execution sequence of the steps listed in this embodiment, and all the solutions implemented by adding, subtracting, and replacing the steps in the prior art according to the principle of the present invention are included in the protection scope of the present invention.

As shown in fig. 7, in an embodiment, the control system of the permanent magnet synchronous motor of the present invention includes an obtaining module 71, an output module 72, a determining module 73, a calculating module 74, a establishing module 75, and a control module 76.

The obtaining module 71 is configured to obtain a real-time rotation speed of the permanent magnet synchronous motor, and a real-time three-phase voltage and a real-time three-phase current of the permanent magnet synchronous motor in the two-phase stationary coordinate system.

The output module 72 is configured to make a difference between the preset rotation speed of the permanent magnet synchronous motor and the real-time rotation speed, input the difference to a PI regulator, and use the output of the PI regulator as a preset instantaneous active power value; the instantaneous reactive power preset value is recorded as zero.

The determining module 73 is configured to determine an argument of a voltage vector corresponding to the real-time three-phase voltage according to the real-time three-phase voltage, and determine a sector where the voltage vector is located according to the argument.

The calculating module 74 is configured to calculate an instantaneous active power actual value and an instantaneous reactive power actual value according to the real-time three-phase voltage and the real-time three-phase current.

The establishing module 75 is configured to establish an optimized switching vector table according to the instantaneous active power preset value, the instantaneous reactive power preset value, the instantaneous active power actual value, the instantaneous reactive power actual value, and the sector.

The control module 76 is configured to select a corresponding voltage vector group from the optimized switching vector table, and obtain a control signal according to the voltage vector group to implement a control function.

It should be noted that the structures and principles of the obtaining module 71, the output module 72, the determining module 73, the calculating module 74, the establishing module 75, and the controlling module 76 correspond to the steps in the control method of the permanent magnet synchronous motor one to one, and therefore, the description is omitted here.

It should be noted that the division of the modules of the above system is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And these modules can be realized in the form of software called by processing element; or may be implemented entirely in hardware; and part of the modules can be realized in the form of calling software by the processing element, and part of the modules can be realized in the form of hardware. For example, the x module may be a processing element that is set up separately, or may be implemented by being integrated in a chip of the system, or may be stored in a memory of the system in the form of program code, and the function of the x module may be called and executed by a processing element of the system. Other modules are implemented similarly. In addition, all or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software.

For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more Digital Signal Processors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), etc. For another example, when one of the above modules is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

The storage medium of the present invention stores thereon a computer program that realizes the above-described control method of the permanent magnet synchronous motor when executed by a processor. The storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic disk, U-disk, memory card, or optical disk.

As shown in fig. 8, the terminal of the present invention includes a processor 81 and a memory 82.

The memory 82 is used for storing computer programs; preferably, the memory 82 includes: various media that can store program codes, such as ROM, RAM, magnetic disk, U-disk, memory card, or optical disk.

The processor 81 is connected to the memory 82 and configured to execute the computer program stored in the memory 82, so that the terminal executes the control method of the permanent magnet synchronous motor.

Preferably, the Processor 81 may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; the integrated Circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components.

It should be noted that the control system of the permanent magnet synchronous motor of the present invention can implement the control method of the permanent magnet synchronous motor of the present invention, but the implementation device of the control method of the permanent magnet synchronous motor of the present invention includes, but is not limited to, the structure of the control system of the permanent magnet synchronous motor as illustrated in the present embodiment, and all the structural modifications and substitutions of the prior art made according to the principle of the present invention are included in the scope of the present invention.

In summary, the control method, system, medium and terminal of the permanent magnet synchronous motor of the present invention realize the control of the permanent magnet synchronous motor by adopting a direct power control mode, which not only has a simple control form as the traditional direct torque control, but also enables the reactive power control of the input motor to approach zero, thereby achieving the goal of unit power factor operation, greatly improving the operation performance of the permanent magnet synchronous motor, and improving the operation efficiency; compared with the traditional control method adopting space voltage vector synthesis, the method does not need park coordinate transformation and park coordinate inverse transformation, and can directly select proper space voltage vectors from a switch vector table according to the requirements of active power and reactive power change to realize the direct control of instantaneous power so as to achieve the aim of speed regulation; the invention aims to simultaneously inhibit the problem pulsation of active power and reactive power, the steady-state fluctuation of the reactive power is obviously inhibited while the steady-state fluctuation of the active power is obviously reduced, further the steady-state fluctuation of torque is inhibited, the control performance of a system is improved, and the aim of saving energy is fulfilled; therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.