Flux weakening control method for permanent magnet synchronous motor
阅读说明：本技术 永磁同步电机弱磁控制方法 (Flux weakening control method for permanent magnet synchronous motor ) 是由 唐婷婷 王声纲 任艳华 朱绯 潘军 陈跃 杨正 王璠 于 2019-09-19 设计创作，主要内容包括：本发明实施例公开一种永磁同步电机弱磁控制方法,涉及永磁同步电机领域,该方法包括：获取永磁同步电机的直流母线电压、d轴参考电压和q轴参考电压；根据所述直流母线电压,确定弱磁开启电压阈值；确定退弱磁电压阈值,所述退弱磁电压阈值小于所述弱磁开启电压阈值；根据所述d轴参考电压和所述q轴参考电压确定目标电压；将所述目标电压与所述弱磁开启电压阈值及所述退弱磁电压阈值比较,确定d轴弱磁电流；根据所述d轴弱磁电流,控制所述永磁同步电机。本发明实施例能够消除电机正常控制和弱磁控制切换的电流跳动,以提高电机运行的稳定性。本发明实施例用于永磁同步电机弱磁控制。(The embodiment of the invention discloses a flux weakening control method for a permanent magnet synchronous motor, which relates to the field of permanent magnet synchronous motors and comprises the following steps: acquiring direct-current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor; determining a weak magnetic start voltage threshold according to the direct current bus voltage; determining a field weakening voltage threshold value, wherein the field weakening voltage threshold value is smaller than the field weakening starting voltage threshold value; determining a target voltage according to the d-axis reference voltage and the q-axis reference voltage; comparing the target voltage with the weak magnetic opening voltage threshold and the weak magnetic removing voltage threshold to determine d-axis weak magnetic current; and controlling the permanent magnet synchronous motor according to the d-axis weak magnetic current. The embodiment of the invention can eliminate the current jump of the switching of normal control and flux weakening control of the motor so as to improve the running stability of the motor. The embodiment of the invention is used for flux weakening control of the permanent magnet synchronous motor.)
1. A flux weakening control method for a permanent magnet synchronous motor is characterized by comprising the following steps:
Acquiring direct-current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor;
determining a weak magnetic start voltage threshold according to the direct current bus voltage;
Determining a field weakening voltage threshold value, wherein the field weakening voltage threshold value is smaller than the field weakening starting voltage threshold value;
Determining a target voltage according to the d-axis reference voltage and the q-axis reference voltage;
Comparing the target voltage with the weak magnetic opening voltage threshold and the weak magnetic removing voltage threshold to determine d-axis weak magnetic current;
And controlling the permanent magnet synchronous motor according to the d-axis weak magnetic current.
2. the method of claim 1, wherein comparing the voltage to the field weakening on voltage threshold and the field weakening voltage threshold, and wherein determining a d-axis field weakening current comprises:
If U iss>U1Then, Iflux＝Iflux-ΔId；
if U iss<U2Then, Iflux＝Iflux+ΔIdAt this time, if Iflux>0, then order Iflux＝0；
If U is2≤Us≤U1then keep current Ifluxthe value is unchanged;
wherein, Usis the target voltage, U1for said field weakening switching-on voltage threshold, U2Is the de-weakening magnetic voltage threshold, IfluxFor said d-axis field weakening current,. DELTA.Idthe preset change step length of the d-axis weak magnetic current is obtained.
3. The method of claim 1 or 2, wherein determining the field weakening turn-on voltage threshold value from the dc bus voltage comprises:
Determining the maximum output voltage threshold of the main circuit inverter according to the direct-current bus voltage;
and determining a weak magnetic opening voltage threshold according to the maximum output voltage threshold.
4. The method of claim 3, wherein determining the maximum output voltage threshold of the main circuit inverter from the DC bus voltage comprises:
According toDetermining the maximum output voltage threshold, wherein UmaxIs the maximum output voltage threshold, UdcIs the dc bus voltage.
5. The method of claim 4, wherein determining a flux weakening turn-on voltage threshold from the maximum output voltage threshold comprises:
According toDetermining the weak magnetic turn-on voltage threshold, wherein U1For said field weakening switching-on voltage threshold, UdcFor said DC bus voltage, UminIs a set value.
6. The method of claim 5, wherein U isminSet to 10.
7. the method of claim 1, wherein the determining a degaussing voltage threshold comprises:
According to U2＝U1- Δ U determines the degaussing voltage threshold, wherein U2For said weakening magnetic voltage threshold, U1and delta U is a set value for the weak magnetic start voltage threshold value.
8. the method of claim 7, wherein Δ U is set to 10.
9. The method of claim 1, wherein the d-axis reference voltage and the q-axis reference voltage are determined from an output of a current loop.
10. The method of claim 1 or 9, wherein determining a target voltage from the d-axis reference voltage and the q-axis reference voltage comprises:
according toThe target voltage is determined and the voltage of the target is,Wherein, UsIs the target voltage, UdFor the d-axis reference voltage, UqIs the q-axis reference voltage.
Technical Field
The invention relates to the field of permanent magnet synchronous motors, in particular to a flux weakening control method of a permanent magnet synchronous motor.
background
The permanent magnet synchronous motor can operate in a high-speed range and is widely applied to the industrial field. When the permanent magnet synchronous motor works at a higher frequency, the rotating speed is often influenced to be increased due to the voltage limit output by the inverter and the space vector of the motor control voltage exceeding a voltage limit circle. At present, the rotating speed is mostly controlled by weak magnetism, namely: when the control voltage reaches the voltage limit which can be output by the inverter, the stator current is adjusted, the stator straight-axis demagnetizing current component is increased, the magnetomotive force generated by the reverse straight-axis current generates a demagnetizing effect on the permanent magnet to weaken the straight-axis magnetic field, and the speed is increased.
In the switching process of normal control and weak magnetic control of the motor, current mutation often occurs to influence the running stability of the motor.
disclosure of Invention
The embodiment of the invention provides a flux weakening control method for a permanent magnet synchronous motor, which can improve the running stability of the motor.
The embodiment of the invention adopts the following technical scheme:
A flux weakening control method for a permanent magnet synchronous motor comprises the following steps:
Acquiring direct-current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor;
Determining a weak magnetic start voltage threshold according to the direct current bus voltage;
Determining a field weakening voltage threshold value, wherein the field weakening voltage threshold value is smaller than the field weakening starting voltage threshold value;
Determining a target voltage according to the d-axis reference voltage and the q-axis reference voltage;
Comparing the target voltage with the weak magnetic opening voltage threshold and the weak magnetic removing voltage threshold to determine d-axis weak magnetic current;
And controlling the permanent magnet synchronous motor according to the d-axis weak magnetic current.
optionally, the comparing the voltage with the field weakening starting voltage threshold and the field weakening voltage threshold, and determining the d-axis field weakening current includes:
If U iss>U1then, Iflux＝Iflux-ΔId；
If U iss<U2Then, Iflux＝Iflux+ΔIdAt this time, if Iflux>0, then order Iflux＝0；
if U is2≤Us≤U1Keep current Ifluxthe value is unchanged;
wherein, UsIs the target voltage, U1For said field weakening switching-on voltage threshold, U2Is the de-weakening magnetic voltage threshold, IfluxFor said d-axis field weakening current,. DELTA.IdThe preset change step length of the d-axis weak magnetic current is obtained.
Optionally,. DELTA.IdSet to 0.05.
optionally, the determining the threshold of the weak magnetic turn-on voltage according to the dc bus voltage includes:
Determining the maximum output voltage threshold of the main circuit inverter according to the direct-current bus voltage;
And determining a weak magnetic opening voltage threshold according to the maximum output voltage threshold.
Optionally, the determining the maximum output voltage threshold of the main circuit inverter according to the dc bus voltage includes:
According toDetermining the maximum output voltage threshold, wherein Umaxis the maximum output voltage threshold, UdcIs the dc bus voltage.
Optionally, the determining the weak magnetic turn-on voltage threshold according to the maximum output voltage threshold includes:
according toDetermining the weak magnetic turn-on voltage threshold, wherein U1For said field weakening switching-on voltage threshold, Udcfor said DC bus voltage, UminIs a set value.
optionally, Uminset to 10.
Optionally, the determining the field weakening voltage threshold includes:
According to U2＝U1- Δ U determines the degaussing voltage threshold, wherein U2For said weakening magnetic voltage threshold, U1And delta U is a set value for the weak magnetic start voltage threshold value.
Optionally, Δ U is set to 10.
Optionally, the d-axis reference voltage and the q-axis reference voltage are determined according to an output of the current loop.
optionally, the determining a target voltage according to the d-axis reference voltage and the q-axis reference voltage includes:
According toThe target voltage is determined and the voltage of the target is,Wherein, Usis the target voltage, UdFor the d-axis reference voltage, UqIs the q-axis reference voltage.
The permanent magnet synchronous motor field weakening control method based on the technical scheme includes the steps of obtaining direct current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor, determining a field weakening starting voltage threshold according to the direct current bus voltage, determining a field weakening voltage threshold, determining a field weakening current threshold smaller than the field weakening starting voltage threshold, determining target voltage according to the d-axis reference voltage and the q-axis reference voltage, comparing the target voltage with the field weakening starting voltage threshold and the field weakening voltage threshold, determining d-axis field weakening current, and controlling the permanent magnet synchronous motor according to the d-axis field weakening current. Therefore, d-axis weak magnetic current is determined according to the current bus voltage, d-axis reference voltage and q-axis reference voltage, and the permanent magnet synchronous motor is controlled based on the d-axis weak magnetic current, so that the running stability of the motor is improved.
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 flux weakening control of a permanent magnet synchronous motor according to an 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.
The embodiment of the invention provides a permanent magnet synchronous motor field weakening control method, which comprises the steps of obtaining direct current bus voltage and d-axis and q-axis reference voltages, and obtaining a field weakening starting voltage threshold value U according to the relation between the direct current bus voltage and the maximum voltage amplitude value capable of being output by a main circuit inverter1Setting a voltage threshold U for weakening magnetism2Obtaining the voltage U from the d-axis and q-axis reference voltagessCompare UsAnd a voltage threshold value U1And a voltage threshold U2To generate a d-axis reference current. And voltage thresholds of the flux-weakening and flux-weakening are different, and a voltage difference exists, so that the phenomenon that the flux-weakening and flux-weakening are continuously fed and the flux-weakening and flux-weakening are not stable under certain special conditions can be avoided. When the embodiment of the invention performs flux weakening and flux weakening,d-axis weak magnetic current Ifluxis gradually changed. The invention can eliminate the current jump of the normal control and the weak magnetic control switching of the motor, and reduce the unstable phenomenon, thereby improving the stability of the motor operation.
As shown in fig. 1, an embodiment of the present invention provides a method for controlling field weakening of a permanent magnet synchronous motor, including:
11. Acquiring direct-current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor;
12. Determining a weak magnetic start voltage threshold according to the direct current bus voltage;
13. Determining a field weakening voltage threshold value, wherein the field weakening voltage threshold value is smaller than the field weakening starting voltage threshold value;
14. determining a target voltage according to the d-axis reference voltage and the q-axis reference voltage;
15. Comparing the target voltage with the weak magnetic opening voltage threshold and the weak magnetic removing voltage threshold to determine d-axis weak magnetic current;
16. And controlling the permanent magnet synchronous motor according to the d-axis weak magnetic current.
The method for controlling the field weakening of the permanent magnet synchronous motor comprises the steps of obtaining direct current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor, determining a field weakening starting voltage threshold according to the direct current bus voltage, determining a field weakening voltage threshold, wherein the field weakening voltage threshold is smaller than the field weakening starting voltage threshold, determining target voltage according to the d-axis reference voltage and the q-axis reference voltage, comparing the target voltage with the field weakening starting voltage threshold and the field weakening voltage threshold, determining d-axis field weakening current, and controlling the permanent magnet synchronous motor according to the d-axis field weakening current. Therefore, d-axis weak magnetic current is determined according to the current bus voltage, d-axis reference voltage and q-axis reference voltage, and the permanent magnet synchronous motor is controlled based on the d-axis weak magnetic current, so that the running stability of the motor is improved.
In one embodiment, the comparing the voltage to the field weakening turn-on voltage threshold and the field weakening voltage threshold, and the determining the d-axis field weakening current comprises:
if U iss>U1Then, Iflux＝Iflux-ΔId；
If U iss<U2Then, Iflux＝Iflux+ΔIdAt this time, if Iflux>0, then order Iflux＝0；
if U is2≤Us≤U1Keep current IfluxThe value is unchanged;
wherein, UsIs the target voltage, U1for said field weakening switching-on voltage threshold, U2Is the de-weakening magnetic voltage threshold, IfluxFor said d-axis field weakening current,. DELTA.IdThe preset change step length of the d-axis weak magnetic current is obtained. Wherein, Delta IdThe value may be set to 0.05, or may be set to other values according to a specific application scenario, which is not limited in the embodiment of the present invention.
In one embodiment, the determining the field weakening turn-on voltage threshold value according to the dc bus voltage includes:
Determining the maximum output voltage threshold of the main circuit inverter according to the direct-current bus voltage;
And determining a weak magnetic opening voltage threshold according to the maximum output voltage threshold.
in one embodiment, the determining the maximum output voltage threshold of the main circuit inverter from the dc bus voltage includes:
According todetermining the maximum output voltage threshold, wherein UmaxIs the maximum output voltage threshold, UdcIs the dc bus voltage.
Optionally, the determining the weak magnetic turn-on voltage threshold according to the maximum output voltage threshold includes:
According toDetermining the weak magnetic turn-on voltage threshold, wherein U1For said field weakening to switch on the voltage thresholdValue UdcFor said DC bus voltage, Uminis a set value.
in one embodiment, UminThe value is set to 10, and may also be set to other values according to a specific application scenario, which is not limited in the embodiment of the present invention.
in one embodiment, the determining the demagnetization voltage threshold comprises:
according to U2＝U1- Δ U determines the degaussing voltage threshold, wherein U2For said weakening magnetic voltage threshold, U1and delta U is a set value for the weak magnetic start voltage threshold value.
In an embodiment, Δ U may be specifically adjusted according to an actual situation, for example, Δ U is set to 10, and may also be set to other values according to a specific application scenario, which is not limited in the embodiment of the present invention.
In one embodiment, the d-axis reference voltage and the q-axis reference voltage are determined from the output of a current loop.
In one embodiment, the determining a target voltage from the d-axis reference voltage and the q-axis reference voltage comprises:
According tothe target voltage is determined and the voltage of the target is,Wherein, UsIs the target voltage, Udfor the d-axis reference voltage, UqIs the q-axis reference voltage.
The permanent magnet synchronous motor field weakening control method based on the technical scheme includes the steps of obtaining direct current bus voltage, d-axis reference voltage and q-axis reference voltage of the permanent magnet synchronous motor, determining a field weakening starting voltage threshold according to the direct current bus voltage, determining a field weakening voltage threshold, determining a field weakening current threshold smaller than the field weakening starting voltage threshold, determining target voltage according to the d-axis reference voltage and the q-axis reference voltage, comparing the target voltage with the field weakening starting voltage threshold and the field weakening voltage threshold, determining d-axis field weakening current, and controlling the permanent magnet synchronous motor according to the d-axis field weakening current. Therefore, the current jump before the switching of the normal control and the flux weakening control of the motor is eliminated, and the running stability of the motor is improved.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
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