阅读说明：本技术 一种永磁同步电机v/f控制定子电阻补偿方法及系统 (permanent magnet synchronous motor V/F control stator resistance compensation method and system ) 是由 华青松 徐晓通 何袁生 丁茂起 李力 于 2019-09-09 设计创作，主要内容包括：本申请提供了一种永磁同步电机V/F控制定子电阻补偿方法及系统,其采用的补偿算法是在传统V/F控制算法的定子电压前加入正反馈环节用于电压补偿构成闭环控制,具体做法是采集永磁同步电机的三相电流,利用Park变换和Clark变换将三相电流变换到以定子电压矢量为d轴的同步旋转坐标上,得到同步旋转坐标下的分解电流I<Sub>d</Sub>,I<Sub>d</Sub>乘上定子电阻R<Sub>s</Sub>,得到定子电阻压降△U,用于电压补偿,提高了定子电压,使电机启动转矩增大,保证了电机能顺利启动,提高了电机的启动性能和低速性能。本申请的技术方案简单实用,具有广泛的应用前景。(The application provides permanent magnet synchronous motor V/F control stator resistance compensation methods and systems, the compensation algorithm is that a positive feedback link is added before the stator voltage of the traditional V/F control algorithm for voltage compensation to form closed-loop control, the specific method is to collect the three-phase current of the permanent magnet synchronous motor, the three-phase current is converted to the synchronous rotation coordinate with the stator voltage vector as the d axis by utilizing Park conversion and Clark conversion, and the decomposition current I under the synchronous rotation coordinate is obtained d ，I d Multiplied by the stator resistance R s The stator resistance voltage drop △ U is obtained and used for voltage compensation, the stator voltage is improved, the starting torque of the motor is increased, smooth starting of the motor is guaranteed, and the starting performance and the low-speed performance of the motor are improved.)

1, permanent magnet synchronous motor V/F control stator resistance compensation method, characterized by, the method includes:

s1, obtaining a stator resistance voltage drop compensation relation based on the parameters of the motor when the motor operates in a low-speed area;

s2, obtaining a stator voltage U modulus value based on the resistance voltage drop compensation and the motor back electromotive force E;

s3, obtaining a motor voltage angle theta based on given frequency, generating output voltage through a PWM unit based on the motor voltage angle theta and a stator voltage U-mode value, and transmitting the output voltage to a motor;

s4, collecting three-phase current of the motor, converting the three-phase current to a synchronous rotation coordinate with a stator voltage vector as a d axis through coordinate conversion, and obtaining a decomposition current I under the synchronous rotation coordinate_dBased on the I_dStator resistor R_sTo obtain a fixedAnd the sub-resistor voltage drop is used for voltage compensation.

2. The method according to claim 1, wherein in S1, the compensation relation of the resistance drop is:

ΔU＝I_dR_s

wherein, Delta U is stator resistance voltage drop, I_dFor resolving currents in synchronous rotation coordinates, R_sIs the stator resistance.

3. The method according to claim 1, wherein in S2, the counter electromotive force E of the motor is a product of a given frequency and a voltage frequency coefficient;

the pressure frequency coefficient K is as follows: k4.44 x K_EPhi, wherein K_EIs a proportionality constant and phi is a main flux.

4. The method of claim 3, wherein the stator voltage modulo is a sum of the motor back-emf E and a stator resistive voltage drop.

5. The method according to claim 3, wherein in the S3, the motor voltage angle θ is obtained by integrating the given frequency.

6. The method according to claim 1, wherein in S4, the transformation of the three-phase current to the synchronous rotation coordinate with the stator voltage vector as the d-axis by coordinate transformation is performed by:

firstly, the three-phase current is converted into a static coordinate system, and then the current in the static coordinate system is converted into a synchronous rotating coordinate with a stator voltage vector as a d axis.

7, permanent magnet synchronous machine V/F control stator resistance compensation system, characterized in that, the system includes:

the voltage-frequency conversion module is used for obtaining a counter electromotive force E of the motor based on a given frequency;

the integration module is used for obtaining a motor voltage angle theta based on the given frequency;

the compensation module is used for obtaining a stator voltage U modulus value based on the motor back electromotive force E and the stator resistance voltage drop; the compensation module is connected with the voltage-frequency conversion module and the stator resistor to receive the counter electromotive force E of the motor and the voltage drop of the stator resistor;

the PWM module is connected with the compensation module, the integration module and the motor and used for generating output voltage and transmitting the output voltage to the motor;

and the coordinate transformation module is connected with the integration module and the motor and used for transforming the three-phase current to a synchronous rotation coordinate with the stator voltage vector as a d axis based on the motor voltage angle theta and obtaining the decomposition current in the synchronous rotation coordinate.

8. The system of claim 7, wherein the stator resistance drop is obtained from the stator resistance and a resolved current at a synchronous rotation coordinate.

9. The system of claim 7, wherein the motor voltage angle θ is obtained by integrating the given frequency.

Technical Field

The invention belongs to the technical field of permanent magnet synchronous motor V/F control, and particularly relates to novel permanent magnet synchronous motor V/F control stator resistance compensation methods and systems.

Background

The control method of the permanent magnet synchronous motor is mainly divided into vector control, direct torque control, scalar control (V/F control), vector control and direct torque control, the control precision is high, the dynamic response is fast, but the algorithm is complex and expensive, the dependence degree on motor parameters is high, the scalar control algorithm is simple and reliable, the control is not dependent on motor parameters, and the control method is very suitable for fan water pump type loads.

Accordingly, the present invention provides simplified methods and systems for compensating for the voltage drop across the stator resistor, so as to greatly reduce the complexity of the control while ensuring a good control effect.

Disclosure of Invention

The technical problem to be solved by the invention is to provide permanent magnet synchronous motor V/F control stator resistance compensation methods and systems, to improve the starting performance and low speed performance of the motor, to solve the above-mentioned deficiencies in the prior art, the invention provides the following technical solutions:

, the invention provides a V/F control stator resistance compensation method for a permanent magnet synchronous motor, which comprises the following steps:

s1, obtaining a stator resistance voltage drop compensation relation based on the parameters of the motor when the motor operates in a low-speed area;

s2, obtaining a stator voltage U modulus value based on the resistance voltage drop compensation and the motor back electromotive force E;

s3, obtaining a motor voltage angle theta based on given frequency, generating output voltage through a PWM unit based on the motor voltage angle theta and a stator voltage U-mode value, and transmitting the output voltage to a motor;

s4, collecting three-phase current of the motor, converting the three-phase current to a synchronous rotation coordinate with a stator voltage vector as a d axis through coordinate conversion, and obtaining a decomposition current I under the synchronous rotation coordinate_dBased on the I_dStator resistor R_sAnd obtaining the resistance voltage drop of the stator for voltage compensation.

Preferably, in S1, the resistance drop compensation relationship is:

ΔU＝IdRs

wherein, Delta U is stator resistance voltage drop, I_dFor resolving currents in synchronous rotation coordinates, R_sIs the stator resistance.

Preferably, in S2, the counter-electromotive force E of the motor is a product of a given frequency and a voltage frequency coefficient;

the pressure frequency coefficient K is as follows: k4.44 x K_EPhi, wherein K_EIs a proportionality constant and phi is a main flux.

Preferably, the stator voltage modulus U is the sum of the motor back electromotive force E and the stator resistance voltage drop.

Preferably, in S3, the motor voltage angle θ is obtained by integrating the given frequency.

Preferably, in S4, the transformation of the three-phase current to the synchronous rotation coordinate with the stator voltage vector as the d-axis by coordinate transformation is performed by:

firstly, the three-phase current is converted into a static coordinate system, and then the current in the static coordinate system is converted into a synchronous rotating coordinate with a stator voltage vector as a d axis.

In addition, the invention also discloses a resistance compensation system for the V/F control stator of the permanent magnet synchronous motors, which is characterized by comprising the following components:

the voltage-frequency conversion module is used for obtaining a counter electromotive force E of the motor based on a given frequency;

the integration module is used for obtaining a motor voltage angle theta based on the given frequency;

the compensation module is used for obtaining a stator voltage U modulus value based on the motor back electromotive force E and the stator resistance voltage drop; the compensation module is connected with the voltage-frequency conversion module and the stator resistor to receive the counter electromotive force E of the motor and the voltage drop of the stator resistor;

the PWM module is connected with the compensation module, the integration module and the motor and used for generating output voltage and transmitting the output voltage to the motor;

and the coordinate transformation module is connected with the integration module and the motor and used for transforming the three-phase current to a synchronous rotation coordinate with the stator voltage vector as a d axis based on the motor voltage angle theta and obtaining the decomposition current in the synchronous rotation coordinate.

Preferably, the stator resistance voltage drop is obtained by the stator resistance and the resolved current in the synchronous rotation coordinate.

Preferably, the motor voltage angle θ is obtained by integrating the given frequency.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects that a positive feedback link is added before the stator voltage of the traditional V/F control method for voltage compensation to form closed-loop control, the stator voltage is improved, the starting torque of the motor is increased, the motor can be started smoothly, and the starting performance and the low-speed performance of the motor are improved.

Drawings

FIG. 1 is a voltage vector diagram of a motor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a stator resistance compensation structure according to an embodiment of the present invention;

FIG. 3 is a graph of the conventional V/F controlled steady state current voltage waveform at a low speed of 120r/min according to an embodiment of the present invention;

FIG. 4 is a graph of the V/F controlled steady state current voltage waveform at a low speed of 120r/min according to an embodiment of the present invention;

FIG. 5 is a waveform of the V/F controlled rotation speed according to the embodiment of the present invention;

FIG. 6 is a torque waveform of V/F control according to the embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only partial embodiments of of the present invention, rather than all embodiments.

The present invention will be further described in with reference to the following drawings and examples.