阅读说明：本技术 变频电机控制方法 (Variable frequency motor control method ) 是由 陈跃 涂小平 王声纲 朱绯 高向军 于 2019-11-20 设计创作，主要内容包括：本发明实施例公开一种变频电机控制方法,能够提高电机带背压启动能力,减少带背压启动失败。本发明实施例通过获取变频电机α轴电压、β轴电压,并获取α轴电流、β轴电流,根据α轴电压、β轴电压、α轴电流、β轴电流,确定变频电机转子轴误差,根据转子轴误差确定变频电机的转子转速和转子位置,根据转子转速和转子位置对变频电机进行控制。从而实现根据变频电机的电压电流确定转子转速和转子位置,进一步根据转子转速和转子位置对变频电机进行控制,从而能够提高电机带背压启动能力,减少带背压启动失败。本发明实施例主要用于变频电机控制。(The embodiment of the invention discloses a control method of a variable frequency motor, which can improve the back pressure starting capability of the motor and reduce the failure of the back pressure starting. According to the embodiment of the invention, the rotor shaft error of the variable frequency motor is determined according to the alpha shaft voltage, the beta shaft voltage, the alpha shaft current and the beta shaft current by acquiring the alpha shaft voltage and the beta shaft voltage of the variable frequency motor, the rotor speed and the rotor position of the variable frequency motor are determined according to the rotor shaft error, and the variable frequency motor is controlled according to the rotor speed and the rotor position. Therefore, the rotor speed and the rotor position are determined according to the voltage and the current of the variable frequency motor, the variable frequency motor is further controlled according to the rotor speed and the rotor position, the starting capacity of the motor with back pressure can be improved, and the failure of starting with the back pressure is reduced. The embodiment of the invention is mainly used for controlling the variable frequency motor.)

1. A method for controlling a variable frequency motor is characterized by comprising the following steps:

obtaining alpha-axis voltage V of variable frequency motor_αBeta axis voltage V_αAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_β；

According to the alpha-axis voltage V_αThe beta axis voltage V_αThe alpha axis first current I_αThe beta axis first current I_βDetermining a second current of the alpha shaft of the variable frequency motor

According to the second current of the alpha shaft of the variable frequency motor

determining the rotor position theta of the variable frequency motor according to the rotor rotating speed omega of the variable frequency motor;

and controlling the variable frequency motor according to the rotor rotating speed omega and the rotor position theta.

2. The method according to claim 1, wherein the obtaining of the alpha-axis voltage V of the variable frequency motor_αBeta axis voltage V_βAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_βThe method comprises the following steps:

establishing a real model of the variable frequency motor:

wherein the content of the first and second substances,

obtaining the alpha-axis voltage V of the variable frequency motor according to the real model of the variable frequency motor_αBeta axis voltage V_βAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_β。

3. The method of claim 2, wherein the establishing a real model of the variable frequency motor comprises:

determining an alpha axis and a beta axis of the variable frequency motor as fixed coordinate axes, determining a d axis and a q axis as rotating coordinate axes rotating along with a motor rotor, and obtaining a motor equation of the variable frequency motor, wherein the d axis is consistent with the motor rotor in direction:

wherein the p-operator represents a differential operation, the p-operator being based on

further, it is obtained that:

obtaining

4. The method of claim 2, wherein the voltage V is based on the alpha axis_αThe beta axis voltage V_αThe alpha axis first current I_αThe beta axis first current I_βDetermining a second alpha-axis current of the variable frequency motorSecond beta axis current

establishing a sliding mode observer model according to the real model of the variable frequency motor;

determining the second alpha-axis current of the variable frequency motor according to the sliding mode observer modelSecond beta axis current

5. The method according to claim 4, wherein the determining the second alpha-axis current of the variable frequency motor is performed according to the sliding-mode observer model

obtaining the following data according to the sliding mode observer model:

further, obtaining a second alpha-axis current of the variable frequency motor

6. the method of claim 4, wherein the second current is based on an alpha axis of the inverter motor

according to the electromotive force e of the variable frequency motor_α、e_βDetermining the back electromotive force e of the variable frequency motor_α'、e_β'；

According to the changeCounter electromotive force e of frequency motor_α'、e_β', determining the rotor shaft error delta theta of the variable frequency motor.

7. Method according to claim 6, characterized in that said electromotive force e according to said variable frequency motor_α、e_βDetermining the back electromotive force e of the variable frequency motor_α'、e_β' comprising:

according to

the electromotive force e of the variable frequency motor_αAnd e_βLow-pass filtering is carried out to obtain the back electromotive force e of the variable frequency motor_α'、e_β'：

Wherein n1(t) and n2(t) are back electromotive force harmonic parts.

8. Method according to claim 7, characterized in that said back electromotive force e according to said variable frequency motor_α'、e_βDetermining the rotor shaft error delta theta of the variable frequency motor comprises the following steps:

according to

9. The method of any of claims 6 to 8, wherein said determining a rotor speed ω of the variable frequency motor from the rotor shaft error Δ θ comprises:

and locking the rotor shaft error delta theta to 0 according to a phase-locked loop to obtain the rotor rotating speed omega of the variable frequency motor.

10. The method of any one of claims 6 to 8, wherein determining the rotor position θ of the inverter motor from the rotor speed ω of the inverter motor comprises:

determining a rotor position theta of the variable frequency motor according to theta ═ ω dt.

Technical Field

The invention relates to the field of household appliance motor control, in particular to a variable frequency motor control method.

Background

The rotating speed and the position are often required to be detected in the control over center of the variable frequency motor. At present, the rotating speed and the position of a motor are mostly estimated by adopting a shaft error through a phase-locked loop control technology, and because the estimation algorithm is slow in convergence, when the motor is started with back pressure, the current waveform is disordered when the motor is dragged to the moment of no-position control switching, and the failure of starting with the back pressure is easily caused.

Disclosure of Invention

The embodiment of the invention provides a control method of a variable frequency motor, which can improve the back pressure starting capability of the motor and reduce the failure of the back pressure starting.

The embodiment of the invention adopts the following technical scheme:

a variable frequency motor control method comprises the following steps:

obtaining alpha-axis voltage V of variable frequency motor_αBeta axis voltage V_αAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_β；

According to the alpha-axis voltage V_αThe beta axis voltage V_αThe alpha axis first current I_αThe beta axis first current I_βDetermining a second current of the alpha shaft of the variable frequency motor

Beta axis second current

According to the second current of the alpha shaft of the variable frequency motorBeta axis second currentDetermining the rotor shaft error delta theta of the variable frequency motor, and determining the rotor rotating speed omega of the variable frequency motor according to the rotor shaft error delta theta;

determining the rotor position theta of the variable frequency motor according to the rotor rotating speed omega of the variable frequency motor;

and controlling the variable frequency motor according to the rotor rotating speed omega and the rotor position theta.

Optionally, the voltage V of the alpha axis of the variable frequency motor is obtained_αBeta axis voltage V_βAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_βThe method comprises the following steps:

establishing a real model of the variable frequency motor:

wherein the content of the first and second substances,

L_dis the d-axis inductance, L of the variable frequency motor_qThe motor q-axis inductance, r is the variable frequency motor phase resistance, omega is the current rotating speed of the variable frequency motor, theta is the rotor position angle of the variable frequency motor, and K_EIs the back electromotive force constant of the variable frequency motor;

obtaining the alpha-axis voltage V of the variable frequency motor according to the real model of the variable frequency motor_αBeta axis voltage V_βAnd obtaining a first current I of the alpha shaft of the variable frequency motor_αBeta axis first current I_β。

Optionally, the establishing a real model of the inverter motor includes:

determining an alpha axis and a beta axis of the variable frequency motor as fixed coordinate axes, determining a d axis and a q axis as rotating coordinate axes rotating along with a motor rotor, and obtaining a motor equation of the variable frequency motor, wherein the d axis is consistent with the motor rotor in direction:

wherein the p-operator represents a differential operation, the p-operator being based on

And

and performing coordinate transformation to obtain:

further, it is obtained that:

obtaining

Wherein L is_dIs the d-axis inductance, L of the variable frequency motor_qThe variable frequency motor q-axis inductance, r, omega, theta, K and theta are the phase resistance, the current rotating speed, the position angle and the position angle of the rotor of the variable frequency motor respectively_EAnd establishing a real model of the variable frequency motor for the counter electromotive force constant of the variable frequency motor.

Optionally, the voltage V is based on the alpha axis_αThe beta axis voltage V_αThe alpha axis first current I_αThe beta axis first current I_βDetermining a second alpha-axis current of the variable frequency motor

Second beta axis currentThe method comprises the following steps:

establishing a sliding mode observer model according to the real model of the variable frequency motor;

determining the second alpha-axis current of the variable frequency motor according to the sliding mode observer model

Second beta axis current

Optionally, the second α -axis current of the variable frequency motor is determined according to the sliding-mode observer model

Second beta axis current

The method comprises the following steps:

obtaining the following data according to the sliding mode observer model:

further, obtaining a second alpha-axis current of the variable frequency motorSecond beta axis current

Wherein the content of the first and second substances,

optionally, the second current is based on the alpha axis of the variable frequency motor

Beta axis second current

Determining the variable frequency motor rotor shaft error Δ θ comprises:

according to the electromotive force e of the variable frequency motor_α、e_βDetermining the back electromotive force e of the variable frequency motor_α'、e_β'；

According to the back electromotive force e of the variable frequency motor_α'、e_β', determining the rotor shaft error delta theta of the variable frequency motor.

Optionally, the electromotive force e of the variable frequency motor is used_α、e_βDetermining the back electromotive force e of the variable frequency motor_α'、e_β' comprising:

according to

Determining the back electromotive force e of the variable frequency motor_α'、e_β', wherein e_α、e_βFor the electromotive force of the variable frequency motor, K is a coefficient introduced for stability, and sign is a sign function;

the electromotive force e of the variable frequency motor_αAnd e_βLow-pass filtering is carried out to obtain the back electromotive force e of the variable frequency motor_α'、e_β'：

Wherein n1(t) and n2(t) are back electromotive force harmonic parts.

Optionally, the counter electromotive force e of the variable frequency motor is used_α'、e_βDetermining the rotor shaft error delta theta of the variable frequency motor comprises the following steps:

according to

And determining the rotor shaft error delta theta of the variable frequency motor, wherein theta 'is the error between the real d-axis position and the estimated d' -axis position of the rotor.

Optionally, the determining the rotor speed ω of the inverter motor according to the rotor shaft error Δ θ includes:

and locking the rotor shaft error delta theta to 0 according to a phase-locked loop to obtain the rotor rotating speed omega of the variable frequency motor.

Optionally, the determining the rotor position θ of the inverter motor according to the rotor rotation speed ω of the inverter motor includes:

determining a rotor position theta of the variable frequency motor according to theta ═ ω dt.

According to the control method of the variable frequency motor based on the technical scheme, the rotor shaft error of the variable frequency motor is determined according to the alpha shaft voltage, the beta shaft voltage, the alpha shaft current and the beta shaft current by obtaining the alpha shaft voltage and the beta shaft voltage of the variable frequency motor, the rotor speed and the rotor position of the variable frequency motor are determined according to the rotor shaft error, and the variable frequency motor is controlled according to the rotor speed and the rotor position. Therefore, the rotor speed and the rotor position are determined according to the voltage and the current of the variable frequency motor, the variable frequency motor is further controlled according to the rotor speed and the rotor position, the starting capacity of the motor with back pressure can be improved, and the failure of starting with the back pressure is reduced.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a flowchart of a method for controlling a variable frequency motor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an axial coordinate transformation provided by an embodiment of the present invention;

fig. 3 is a schematic diagram of the true position and the estimated position of the rotor according to the embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.