CN112470392B - Automatic load compensation method, device, equipment and medium for asynchronous motor - Google Patents
Automatic load compensation method, device, equipment and medium for asynchronous motor Download PDFInfo
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- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H—ELECTRICITY
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Abstract
An automatic load compensation method, device, equipment and medium for an asynchronous motor comprises the following steps: acquiring a space vector angle of rotor flux linkage or rotor back electromotive voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor; according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation; and vectorization compensation is carried out on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current so as to realize dynamic load compensation of the asynchronous motor. Obviously, the stator voltage of the asynchronous motor is compensated according to the constant rotor flux, so that the asynchronous motor can be completely decoupled, the mechanical characteristics of the asynchronous motor in the process of load compensation can be obviously improved by the method, and the problems of over-compensation and under-compensation of the asynchronous motor are avoided.
Description
Technical Field
The invention relates to the technical field of motor control algorithms, in particular to an automatic load compensation method, device, equipment and medium for an asynchronous motor.
Background
The method utilizes the steady-state model of the asynchronous motor to control the output voltage and frequency of the frequency converter, has the advantages of simple realization, strong parameter robustness, simple debugging, low cost and the like, and is widely applied to frequency conversion and speed regulation occasions with low performance requirements. When the asynchronous machine is operating below the fundamental frequencyWhen the asynchronous motor runs, if the magnetic flux is too weak, the iron core of the asynchronous motor cannot be fully utilized, so that the output of the asynchronous motor is insufficient; if the magnetic flux is too large, the iron core of the asynchronous motor is saturated, the exciting current is too large, and the asynchronous motor is damaged due to overheating of the winding of the asynchronous motor in serious cases. The most effective method for solving the problem is as follows: when the asynchronous motor runs below the fundamental frequency, the back electromotive force E of the asynchronous motor is adjusted g And a given frequency f of the frequency converter s The ratio of (A) to (B) is set to be a constant value, and the air gap flux linkage is ensured to be constant.
When the motor runs at high frequency, the back electromotive force of the asynchronous motor is high, the voltage drop of the stator winding resistance and the leakage inductance of the asynchronous motor can be ignored, and the motor is approximately considered as U s ≈E g And when operating at low frequency, the stator voltage U of the asynchronous machine s And a back-emf set voltage E g Both are relatively small, and the stator impedance and leakage inductance voltage drop in the asynchronous motor cannot be ignored. At this time, in order to avoid the problem that the magnetic flux of the asynchronous motor is weak or the load capacity is reduced, the stator voltage U of the asynchronous motor can be artificially adjusted s Raised somewhat in order to compensate for the stator impedance drop of the asynchronous machine. In practical application, because asynchronous motors have different powers, different loads and different reasonable stator voltage drop values to be compensated, the phenomenon of over-compensation or under-compensation of the asynchronous motors is easily caused, and faults such as overcurrent, overload, overheating or locked rotor and the like of the asynchronous motors are caused.
Based on the steady-state mathematical model theory of the asynchronous motor, three methods for compensating the stator voltage of the asynchronous motor exist at present, namely, constant sub-flux control, constant air gap flux control and constant rotor flux control. In the prior art, the constant sub-flux control of the stator voltage of the asynchronous motor is only realized, but the mechanical property of the asynchronous motor adopting the control scheme is poor, and the problem of over-compensation or under-compensation of the stator voltage is not effectively solved. At present, no effective solution exists for the technical problem.
Therefore, the technical problem to be solved by those skilled in the art is how to improve the mechanical characteristics of the asynchronous motor during the load compensation process and avoid the over-compensation and under-compensation problems of the asynchronous motor.
Disclosure of Invention
In view of the above, an object of the present invention is to provide an automatic load compensation method, apparatus, device and medium for an asynchronous motor, so as to improve mechanical characteristics during load compensation of the asynchronous motor and avoid overcompensation and undercompensation problems of the asynchronous motor. The specific scheme is as follows:
an automatic load compensation method of an asynchronous motor comprises the following steps:
acquiring a space vector angle of rotor flux linkage or rotor back electromotive voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation;
and vectorizing and compensating the stator voltage of the asynchronous motor by using the vector control steady-state model of the asynchronous motor, the motor parameters of the asynchronous motor, the torque current and the excitation current so as to realize dynamic load compensation of the asynchronous motor.
Preferably, the process of obtaining the space vector angle of the rotor flux linkage or the rotor back electromotive voltage of the asynchronous motor according to the asynchronous motor vector control steady-state model includes:
obtaining the stator voltage of the asynchronous motor according to the asynchronous motor vector control steady-state model and the vector steady-state phasor diagram of the asynchronous motor;
obtaining a torque angle between a space vector of the stator voltage and a space vector of the rotor back emf voltage using the stator voltage and the motor parameters;
obtaining a spatial vector angle of the rotor back emf according to the torque moment angle;
and acquiring the space vector angle of the rotor magnetic linkage by using the space vector angle of the counter electromotive force of the rotor.
Preferably, the process of decomposing the stator current of the asynchronous motor into the torque current and the excitation current through coordinate transformation according to the spatial vector angle of the rotor flux linkage or the rotor back electromotive force includes:
and orienting the rotor flux linkage according to the space vector angle of the rotor flux linkage, or orienting the rotor back electromotive force according to the space vector angle of the rotor back electromotive force, and carrying out Park conversion on the stator current of the asynchronous motor to obtain the torque current and the excitation current.
Preferably, the vector-controlled steady-state model of the asynchronous motor, the motor parameter of the asynchronous motor, the torque current, and the excitation current are used to perform vectorization compensation on the stator voltage of the asynchronous motor, so as to implement dynamic load compensation on the asynchronous motor, and the vector-controlled steady-state model of the asynchronous motor includes:
acquiring the counter potential voltage of the rotor of the asynchronous motor at a rated frequency according to a no-load experiment, and acquiring a VF curve of the asynchronous motor based on the counter potential voltage of the rotor;
determining voltage vector compensation values of stator voltages of the asynchronous motor on a d axis and a q axis respectively by using the VF curve, the asynchronous motor vector control steady-state model, motor parameters of the asynchronous motor, the torque current and the excitation current;
and determining a stator voltage synthesis instruction amplitude of the asynchronous motor according to the voltage vector compensation value and the counter electromotive voltage of the rotor so as to realize dynamic load compensation of the asynchronous motor.
Preferably, the method further comprises the following steps:
and setting the inductance of the asynchronous motor to be zero, and replacing the VF curve by using a data curve of the ratio of the rated stator voltage and the rated frequency of the asynchronous motor.
Preferably, the method further comprises the following steps:
acquiring a space vector angle of the asynchronous motor air gap flux linkage according to the asynchronous motor vector control steady-state model;
and vectorizing and compensating the stator voltage of the asynchronous motor by utilizing the space vector angle of the air gap flux linkage, the vector control steady-state model of the asynchronous motor and the motor parameters of the asynchronous motor so as to realize dynamic load compensation of the asynchronous motor.
Correspondingly, the invention also discloses an automatic load compensation device of the asynchronous motor, which comprises:
the angle acquisition module is used for acquiring a space vector angle of the rotor flux linkage or the rotor back electromotive force voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
the current decomposition module is used for decomposing the stator current of the asynchronous motor into torque current and exciting current through coordinate transformation according to the space vector angle of the rotor flux linkage or the rotor back electromotive force;
and the load compensation module is used for performing vectorization compensation on the stator voltage of the asynchronous motor by using the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the excitation current so as to realize dynamic load compensation on the asynchronous motor.
Correspondingly, the invention also discloses an automatic load compensation device of the asynchronous motor, which comprises:
a memory for storing a computer program;
a processor for implementing the steps of an automatic load compensation method of an asynchronous machine as disclosed in the foregoing when executing said computer program.
Accordingly, the present invention also discloses a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, implements the steps of a method for automatic load compensation of an asynchronous machine as disclosed in the foregoing.
Therefore, in the automatic load compensation method of the asynchronous motor, firstly, a space vector angle of the rotor flux linkage or the rotor back electromotive voltage of the asynchronous motor is obtained according to the vector control steady-state model of the asynchronous motor; then, according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation, so that the asynchronous motor is decoupled; and finally, vectorizing compensation is carried out on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current so as to realize dynamic load compensation of the asynchronous motor. Obviously, the amplitude compensation of the stator voltage of the asynchronous motor by the method is equivalent to the compensation of the stator voltage of the asynchronous motor according to the constant rotor flux, so that the method can obviously improve the mechanical characteristics in the process of load compensation of the asynchronous motor and avoid the problems of over-compensation and under-compensation of the asynchronous motor. Correspondingly, the automatic load compensation device, the equipment and the medium for the asynchronous motor, which are provided by the invention, also have the beneficial effects.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of an automatic load compensation method for an asynchronous motor according to an embodiment of the present invention;
fig. 2 is a vector steady-state phasor diagram of an asynchronous motor according to an embodiment of the present invention;
fig. 3 is a schematic view of a directional coordinate system of an asynchronous motor according to an embodiment of the present invention;
fig. 4 is a structural diagram of an automatic load compensation device for an asynchronous motor according to an embodiment of the present invention;
fig. 5 is a structural diagram of an automatic load compensation apparatus for an asynchronous motor according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a flowchart of an automatic load compensation method for an asynchronous motor according to an embodiment of the present invention, where the method includes:
step S11: acquiring a space vector angle of rotor flux linkage or rotor back electromotive voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
step S12: according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation;
step S13: and vectorization compensation is carried out on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current so as to realize dynamic load compensation of the asynchronous motor.
In this embodiment, an automatic load compensation method for an asynchronous motor is provided, by which mechanical characteristics during load compensation of the asynchronous motor can be significantly improved, and overcompensation and undercompensation problems of the asynchronous motor are avoided.
Specifically, in this embodiment, a spatial vector angle of the rotor flux linkage of the asynchronous motor or a spatial vector angle of the back emf voltage of the rotor is firstly obtained, wherein in the process of obtaining the spatial vector angle of the rotor flux linkage of the asynchronous motor, the spatial vector angle of the rotor flux linkage of the asynchronous motor can be obtained according to a vector steady-state phasor diagram of the asynchronous motor, a T-I equivalent circuit of the asynchronous motor and a trigonometric function calculation formula.
After the space vector angle of the rotor flux linkage or the rotor back electromotive force of the asynchronous motor is obtained, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation, so that the asynchronous motor is decoupled. And then, vectorization compensation is carried out on the stator voltage of the asynchronous motor based on the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current, so that the automatic load compensation of the asynchronous motor based on the constant rotor flux control is realized.
It can be understood that, because amplitude compensation is performed on the stator voltage of the asynchronous motor by using the constant rotor flux control, complete decoupling of the dq axis current of the asynchronous motor can be realized, so that the mechanical characteristics in the process of load compensation of the asynchronous motor can be obviously improved by the compensation mode, and the problems of over-compensation and under-compensation of the asynchronous motor are avoided. In addition, theoretically, load compensation of an asynchronous motor based on a constant rotor flux can achieve linear mechanical characteristics similar to those of a direct current motor.
It can be seen that, in the automatic load compensation method for the asynchronous motor provided in this embodiment, first, a spatial vector angle of a rotor flux linkage or a rotor back electromotive voltage of the asynchronous motor is obtained according to a vector control steady-state model of the asynchronous motor; then, according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation, so that the asynchronous motor is decoupled; and finally, vectorizing compensation is carried out on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current so as to realize dynamic load compensation of the asynchronous motor. Obviously, the amplitude compensation of the stator voltage of the asynchronous motor by the method is equivalent to the compensation of the stator voltage of the asynchronous motor according to the constant rotor flux, so that the method can obviously improve the mechanical characteristics in the process of load compensation of the asynchronous motor and avoid the problems of over-compensation and under-compensation of the asynchronous motor.
Based on the above embodiment, this embodiment further describes and optimizes the technical solution, and as a preferred implementation, the above steps: the process of obtaining the space vector angle of the rotor flux linkage or the rotor back electromotive force voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor comprises the following steps:
acquiring the stator voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor and the vector steady-state phasor diagram of the asynchronous motor;
acquiring a torque angle between a space vector of the stator voltage and a space vector of the rotor back electromotive force voltage by using the stator voltage and the motor parameters;
acquiring a space vector angle of the rotor back electromotive force according to the torque angle;
and acquiring the space vector angle of the rotor flux linkage by using the space vector angle of the rotor back electromotive force.
In practical application, in order to obtain a space vector angle of an asynchronous motor rotor flux linkage and a space vector angle of rotor back electromotive force voltage, firstly, a stator voltage U of the asynchronous motor is obtained according to an asynchronous motor vector control steady-state model and a vector steady-state phasor diagram of the asynchronous motor s Referring to fig. 2, fig. 2 is a vector steady-state phasor diagram of an asynchronous motor according to an embodiment of the present invention, where the stator voltage is oriented on a γ axis of a γ δ coordinate system, there are:
referring to fig. 3, fig. 3 is a space vector distribution relationship diagram of an asynchronous motor according to an embodiment of the present invention, and a back electromotive voltage of a rotor can be obtained according to the space vector distribution relationship of the asynchronous motor shown in fig. 3 and by combining with a side length calculation of a triangle
I.e.:
in the formula of U s Is the amplitude of the stator voltage of the asynchronous machine, I s Amplitude of stator current, R, for asynchronous machines s Is stator resistance of asynchronous motor, and σ is magnetic leakage coefficient, X s Is the stator inductive reactance of the asynchronous motor,
the angle difference between the output voltage and the current vector of the frequency converter, namely the power factor angle.
Wherein the content of the first and second substances,
in the formula, theta v Is the spatial vector angle, theta, of the stator voltage of an asynchronous machine v ＝∫w s dt，ω s For synchronous electrical angular velocity, i.e. position angle of stator voltage of asynchronous machine, i sd And i sq Stator currents of a d axis and a q axis of the asynchronous motor under a dq coordinate system are respectively.
The voltage vector of the asynchronous motor can be calculated by a trigonometric function calculation formula
And the q-axis of the synchronous rotation dq-coordinate system, i.e. the torque angle between the space vector of the stator voltage and the space vector of the rotor back-emf voltage, wherein the torque angle δ is:
wherein σ is the magnetic leakage coefficient, X s Is the stator inductance of an asynchronous machine, I s Stator current amplitude, R, for an asynchronous machine s Is the stator resistance of the asynchronous motor,
for the angle difference of the output voltage and the current vector of the frequency converter, i.e. the power factor angle, U s Is the amplitude of the stator voltage of the asynchronous motor.
The spatial vector angle theta of the back emf of the rotor of the asynchronous machine is then er Comprises the following steps:
θ er ＝θ v -δ；
since the rotor flux lags the rotor back-emf by 90 °, the rotor flux is emptyAngle of vector theta between r Comprises the following steps:
in the formula, theta v Is the spatial vector angle, theta, of the stator voltage of an asynchronous machine v ＝∫w s dt，ω s Delta is the torque angle for synchronous electrical angular velocity, i.e. the position angle of the stator voltage of the asynchronous machine.
Therefore, the technical scheme provided by the embodiment can enable the acquisition process of the space vector angle of the rotor back electromotive force and the space vector angle of the rotor flux linkage to be more accurate and reliable.
Based on the above embodiments, this embodiment further describes and optimizes the technical solution, and as a preferred implementation, the above steps: the process of decomposing the stator current of an asynchronous motor into a torque current and an excitation current by coordinate transformation according to the spatial vector angle of a rotor flux linkage or a rotor back emf, comprising:
and orienting the rotor flux linkage according to the space vector angle of the rotor flux linkage, or orienting the rotor back electromotive force according to the space vector angle of the rotor back electromotive force, and carrying out Park conversion on the stator current of the asynchronous motor to obtain the torque current and the exciting current.
In this embodiment, according to the oriented coordinate system schematic diagram of the asynchronous motor shown in fig. 3, the steady-state voltage equation of the asynchronous motor oriented according to the flux linkage of the asynchronous motor in the synchronous rotation dq coordinate system can be obtained as follows:
in the formula u sd And u sq Stator voltages i of d-axis and q-axis of the asynchronous machine in dq-coordinate system, respectively sd And i sq Stator currents of d-axis and q-axis of the asynchronous motor in dq coordinate system, R s For stator resistance of asynchronous machines, p being the differential and derivative sign, omega s To synchronize the electrical angleSpeed, σ is the magnetic leakage coefficient, L s Is the stator inductance of an asynchronous machine, L m Is the mutual inductance of an asynchronous machine, L r Is the rotor inductance of an asynchronous machine,. Psi r Is the rotor flux linkage amplitude.
The transformation relation of the stator current of the asynchronous motor from a gamma delta coordinate system to a dq coordinate system is as follows:
in the formula i sd And i sq Stator currents of a d axis and a q axis of the asynchronous motor under a dq coordinate system respectively, delta is a torque angle, i γ And i δ The stator currents of the gamma axis and the delta axis of the asynchronous motor under a gamma delta coordinate system are respectively.
According to the space vector angle of the rotor flux linkage of the asynchronous motor, the stator voltage of the asynchronous motor is transformed to a dq coordinate system oriented according to the rotor flux linkage, namely:
in the formula i sd And i sq Stator currents of d-axis and q-axis of the asynchronous machine in dq-coordinate system, theta r Is the spatial vector angle, i, of the rotor flux linkage sα And i sβ Stator currents of an alpha axis and a beta axis of the asynchronous motor under an alpha and beta coordinate system are respectively.
And then, rotating the dq coordinate axis by 90 degrees anticlockwise to obtain a d 'q' coordinate system of the asynchronous motor oriented according to the counter electromotive force of the rotor, and obtaining a current and voltage equation of the stator current of the asynchronous motor on the d 'q' coordinate axis through park transformation, namely:
then the vector control steady-state mathematical model of the asynchronous motor oriented according to the counter electromotive force of the rotor is as follows:
in the formula i sd' And i sq' Stator currents i of d 'axis and q' axis of asynchronous machine in d 'q' coordinate system sd And i sq Stator currents of d-axis and q-axis of the asynchronous motor in dq coordinate system, R s For stator resistance of asynchronous machines, p being differential and derivative symbols, L s Being stator inductances, omega, of asynchronous machines s For synchronous electrical angular velocity, σ is the magnetic leakage coefficient, L s Is the stator inductance of an asynchronous machine, L m Is the mutual inductance of asynchronous machines, L r Is the rotor inductance of an asynchronous machine,. Psi r Is the rotor flux linkage amplitude.
In addition, i is sd And i sq Torque current and excitation current, i, respectively, obtained by orienting according to the spatial vector angle of the rotor flux linkage sd′ And i sq′ Respectively, the torque current and the excitation current resulting from the orientation according to the spatial vector angle of the rotor back emf.
Obviously, the technical scheme provided by the embodiment can realize complete decoupling of the asynchronous motor.
Based on the above embodiment, this embodiment further describes and optimizes the technical solution, and as a preferred implementation, the above steps: the process of utilizing asynchronous motor vector control steady-state model, motor parameters of asynchronous motor, torque current and exciting current to carry out vectorization compensation on stator voltage of asynchronous motor so as to realize dynamic load compensation on asynchronous motor comprises the following steps:
acquiring the rotor back electromotive force voltage of the asynchronous motor at the rated frequency according to a no-load experiment, and acquiring a VF curve of the asynchronous motor based on the rotor back electromotive force voltage;
determining voltage vector compensation values of stator voltages of the asynchronous motor on a d axis and a q axis respectively by using a VF curve, an asynchronous motor vector control steady-state model, motor parameters of the asynchronous motor, torque current and exciting current;
and determining a stator voltage synthesis instruction amplitude of the asynchronous motor according to the voltage vector compensation value and the counter electromotive voltage of the rotor so as to realize dynamic load compensation of the asynchronous motor.
In the embodiment, firstly, the counter electromotive voltage E of the rotor of the asynchronous motor when the asynchronous motor is unloaded at the rated frequency is obtained according to the no-load experiment rN In practical application, the E can be obtained by acquiring the no-load operation stage in the parameter self-learning process of the asynchronous motor rN Then, based on the rotor back electromotive voltage E rN Obtaining a VF curve of the asynchronous motor, wherein the VF curve is E r /f 1 = const. It will be appreciated that if the ratio E of the back-emf voltage of the rotor to the given frequency is taken r /f 1 = const is used to compensate the stator voltage of the asynchronous machine, i.e. the rotor flux of the asynchronous machine can be kept constant.
Because the vector control steady-state model expression of the asynchronous motor is as follows:
in the formula (I), the compound is shown in the specification,
u sd and u sq Stator voltages i of d-axis and q-axis of the asynchronous machine in dq-coordinate system, respectively sd And i sq Stator currents of d-axis and q-axis of the asynchronous motor in dq coordinate system, omega s For synchronizing the electrical angular velocity, # r For rotor flux linkage amplitude, R s Is the stator resistance of an asynchronous machine, L m Is the mutual inductance of asynchronous machines, L r The magnetic flux leakage coefficient is sigma.
Therefore, the stator voltage U of the asynchronous motor is oriented according to the rotor flux linkage of the asynchronous motor s The resultant command amplitude is:
or the stator voltage U of the asynchronous motor is oriented according to the counter electromotive force of the rotor of the asynchronous motor s The resultant command amplitude is:
in the formula u sq_boost For the voltage compensation value of the asynchronous machine in the q-axis, u sd_boost Compensating value u for voltage of asynchronous motor on d axis sq'_boost For voltage compensation of the asynchronous machine on the q' axis, u sd'_boost For compensating the voltage R of the asynchronous machine on the d' axis s Is the stator resistance of an asynchronous machine i sd And i sq Stator currents, ω, of d-axis and q-axis respectively of the asynchronous machine in dq-coordinate system s For synchronous electrical angular velocity, σ is the magnetic leakage coefficient, L s Is the stator inductance of an asynchronous machine i sd' And i sq′ Stator currents of d-axis and q-axis of the asynchronous machine in d 'q' coordinate system, respectively, E r ' is the equivalent rotor back emf of the vector control steady state model of the asynchronous machine;
wherein the content of the first and second substances,
in the formula, L m Is the mutual inductance of asynchronous machines, L r Is the rotor inductance of an asynchronous machine, E r Is the back electromotive voltage of the rotor of an asynchronous machine, f s For a given frequency of the frequency converter, f sN Is the rated frequency of the frequency converter, E rN The back electromotive voltage of the rotor when the asynchronous motor is unloaded at a rated frequency is obtained.
Therefore, the technical scheme provided by the embodiment can further ensure the accuracy and reliability in the dynamic load compensation process of the asynchronous motor.
As a preferred embodiment, the method further comprises:
the inductance of the asynchronous motor is set to zero and the VF curve is replaced by a data curve of the ratio of the rated stator voltage and the rated frequency of the asynchronous motor.
In practical application, in order to simplify the stator voltage amplitude U of the asynchronous motor s The amplitude compensation formula of (2) can only consider the influence of low-frequency stator resistance in practical application, and does not consider inductance L s I.e. the inductance L of the asynchronous machine s Set to zero and using the VF-curve of the ratio between the rated stator voltage and the rated frequency of the asynchronous machine also prevents overcompensation of medium and high frequencies, so that, in this case, the stator voltage U of the asynchronous machine, oriented according to the rotor flux linkage of the asynchronous machine, is oriented s The resultant command amplitude is:
in the formula (I), the compound is shown in the specification,
u sq_boost for the voltage compensation value of the asynchronous machine in the q-axis, u sd_boost For voltage compensation of asynchronous machines in d-axis, R s Being stator resistance, U, of asynchronous machines sN Is the rated stator voltage of the asynchronous machine, f sN For the rated frequency, f, of the asynchronous machine s For a given frequency of the frequency converter, i sd And i sq Stator currents of a d axis and a q axis of the asynchronous motor under a dq coordinate system are respectively.
Based on the same principle, the counter electromotive force of the rotor of the asynchronous motor can be oriented, and the electronic voltage synthesis instruction amplitude of the asynchronous motor is obtained, which is not described in detail herein.
Obviously, the technical scheme provided by the embodiment can relatively reduce the compensation difficulty in the dynamic load compensation process of the asynchronous motor.
Based on the above embodiment, this embodiment further describes and optimizes the technical solution, and as a preferred implementation, the load compensation method of the asynchronous motor further includes:
acquiring a space vector angle of an air gap flux linkage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
and vectorization compensation is carried out on the stator voltage of the asynchronous motor by utilizing the space vector angle of the air gap flux linkage, the vector control steady-state model of the asynchronous motor and the motor parameters of the asynchronous motor, so as to realize dynamic load compensation of the asynchronous motor.
In practical application, the amplitude compensation can be performed on the stator voltage of the asynchronous motor based on a steady-state mathematical model of the asynchronous motor and a space vector angle of an air gap flux linkage of the asynchronous motor. Specifically, the air gap flux linkage space vector angle of the asynchronous motor can be obtained according to the vector control steady-state model of the asynchronous motor, that is, the voltage space vector of the asynchronous motor is obtained through calculation according to the vector distribution relation and the trigonometric function of the T-shaped equivalent circuit of the asynchronous motor
And the included angle power angle delta of the q axis synchronously rotating the dq coordinate axis according to the orientation of the air gap flux linkage of the asynchronous motor m Wherein, delta m The calculation expression of (a) is:
in the formula, X ls For stator leakage reactance of asynchronous machines, I s Is the amplitude of the stator current of the asynchronous motor,
is the angle difference, U, between the output voltage and the current vector of the frequency converter s Is the stator voltage of an asynchronous machine, R s Is the stator resistance of the asynchronous motor.
The space vector angle of the counter electromotive force of the asynchronous motor rotor is as follows:
θ mr ＝θ v -δ m ；
then, the spatial vector angle of the air gap flux linkage of the asynchronous motor is:
by using the spatial vector angle theta of the air gap flux linkage m The process of vectorization compensation of the stator voltage of the asynchronous motor by the asynchronous motor vector control steady-state model and the motor parameters of the asynchronous motor is similar to the method of vectorization compensation of the stator voltage of the asynchronous motor according to the rotor flux linkage or according to the space vector angle of the counter electromotive force of the rotor, and is well known by those skilled in the art, so details of the vectorization compensation are not described in this embodiment.
Obviously, the load compensation of the asynchronous motor by the method is equivalent to the compensation of the stator voltage of the asynchronous motor by using the constant air gap flux based on the T-shaped steady-state circuit mathematical model of the asynchronous motor, so that the problems of over-compensation and under-compensation of the asynchronous motor can be relatively avoided by the method, but the mechanical property is slightly poorer than the effect of the directional compensation of the rotor flux linkage.
Referring to fig. 4, fig. 4 is a structural diagram of an automatic load compensation device for an asynchronous motor according to an embodiment of the present invention, where the load compensation device includes:
the angle acquisition module 21 is used for acquiring a space vector angle of the rotor flux linkage or the rotor back electromotive voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
the current decomposition module 22 is used for decomposing the stator current of the asynchronous motor into torque current and exciting current through coordinate transformation according to the space vector angle of the rotor flux linkage or the rotor back electromotive force;
and the load compensation module 23 is configured to perform vectorization compensation on the stator voltage of the asynchronous motor by using the asynchronous motor vector control steady-state model, the motor parameter of the asynchronous motor, the torque current, and the excitation current, so as to implement dynamic load compensation on the asynchronous motor.
The automatic load compensation device of the asynchronous motor provided by the embodiment of the invention has the beneficial effects of the disclosed automatic load compensation method of the asynchronous motor.
Referring to fig. 5, fig. 5 is a structural diagram of an automatic load compensation device for an asynchronous motor according to an embodiment of the present invention, where the device includes:
a memory 31 for storing a computer program;
a processor 32 for implementing the steps of the method for automatic load compensation of an asynchronous machine as disclosed in the foregoing when executing a computer program.
The automatic load compensation equipment of the asynchronous motor provided by the embodiment of the invention has the beneficial effects of the disclosed automatic load compensation method of the asynchronous motor.
Accordingly, the embodiment of the present invention further discloses a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the automatic load compensation method for an asynchronous motor as disclosed in the foregoing are implemented.
The computer-readable storage medium provided by the embodiment of the invention has the beneficial effects of the automatic load compensation method for the asynchronous motor disclosed in the foregoing.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "...," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
The above detailed description is provided for the automatic load compensation method, apparatus, device and medium of the asynchronous motor, and the specific examples are applied herein to explain the principle and implementation of the present invention, and the description of the above embodiments is only used to help understanding the method and core ideas of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (8)
1. An automatic load compensation method for an asynchronous motor, comprising:
acquiring a space vector angle of rotor flux linkage or rotor back electromotive force voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
according to the space vector angle of the rotor flux linkage or the rotor back electromotive force, the stator current of the asynchronous motor is decomposed into torque current and exciting current through coordinate transformation;
vectorization compensation is carried out on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the exciting current so as to realize dynamic load compensation on the asynchronous motor;
the process of obtaining the space vector angle of the rotor flux linkage or the rotor back electromotive force voltage of the asynchronous motor according to the asynchronous motor vector control steady-state model comprises the following steps:
acquiring the stator voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor and the vector steady-state phasor diagram of the asynchronous motor;
acquiring a torque angle between a space vector of the stator voltage and a space vector of the rotor back-emf voltage using the stator voltage and the motor parameters;
obtaining a spatial vector angle of the rotor back emf according to the torque moment angle;
and acquiring the space vector angle of the rotor magnetic linkage by using the space vector angle of the counter electromotive force of the rotor.
2. The automatic load compensation method according to claim 1, wherein the process of decomposing the stator current of the asynchronous machine into a torque current and an excitation current by coordinate transformation according to the spatial vector angle of the rotor flux linkage or the rotor back electromotive force comprises:
and orienting the rotor flux linkage according to the space vector angle of the rotor flux linkage, or orienting the rotor back electromotive force according to the space vector angle of the rotor back electromotive force, and carrying out Park conversion on the stator current of the asynchronous motor to obtain the torque current and the excitation current.
3. The automatic load compensation method according to claim 1, wherein the vectorization compensation of the stator voltage of the asynchronous machine using the asynchronous machine vector control steady-state model, the machine parameters of the asynchronous machine, the torque current and the excitation current to achieve dynamic load compensation of the asynchronous machine comprises:
acquiring the rotor back electromotive force voltage of the asynchronous motor at a rated frequency according to a no-load experiment, and acquiring a VF curve of the asynchronous motor based on the rotor back electromotive force voltage;
determining voltage vector compensation values of stator voltages of the asynchronous motor on a d axis and a q axis respectively by using the VF curve, the asynchronous motor vector control steady-state model, motor parameters of the asynchronous motor, the torque current and the excitation current;
and determining a stator voltage synthesis instruction amplitude of the asynchronous motor according to the voltage vector compensation value and the rotor back electromotive voltage so as to realize dynamic load compensation of the asynchronous motor.
4. The automatic load compensation method of claim 3, further comprising:
and setting the inductance of the asynchronous motor to be zero, and replacing the VF curve by using a data curve of the ratio of the rated stator voltage and the rated frequency of the asynchronous motor.
5. The automatic load compensation method of any one of claims 1 to 4, further comprising:
acquiring a space vector angle of the asynchronous motor air gap flux linkage according to the asynchronous motor vector control steady-state model;
and vectorizing and compensating the stator voltage of the asynchronous motor by utilizing the space vector angle of the air gap flux linkage, the vector control steady-state model of the asynchronous motor and the motor parameters of the asynchronous motor so as to realize dynamic load compensation of the asynchronous motor.
6. An automatic load compensation device of an asynchronous motor, comprising:
the angle acquisition module is used for acquiring a space vector angle of the rotor flux linkage or the rotor back electromotive force voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor;
the current decomposition module is used for decomposing the stator current of the asynchronous motor into torque current and exciting current through coordinate transformation according to the space vector angle of the rotor flux linkage or the rotor back electromotive force;
the load compensation module is used for carrying out vectorization compensation on the stator voltage of the asynchronous motor by utilizing the asynchronous motor vector control steady-state model, the motor parameters of the asynchronous motor, the torque current and the excitation current so as to realize dynamic load compensation on the asynchronous motor;
the process of obtaining the space vector angle of the rotor flux linkage or the rotor back electromotive force voltage of the asynchronous motor according to the vector control steady-state model of the asynchronous motor comprises the following steps:
obtaining the stator voltage of the asynchronous motor according to the asynchronous motor vector control steady-state model and the vector steady-state phasor diagram of the asynchronous motor;
obtaining a torque angle between a space vector of the stator voltage and a space vector of the rotor back emf voltage using the stator voltage and the motor parameters;
acquiring a space vector angle of the rotor back electromotive force according to the torque angle;
and acquiring the space vector angle of the rotor flux linkage by using the space vector angle of the rotor back electromotive force.
7. An automatic load compensation apparatus for an asynchronous motor, comprising:
a memory for storing a computer program;
processor for implementing the steps of a method for automatic load compensation of an asynchronous machine according to any of claims 1 to 5 when executing said computer program.
8. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program, when being executed by a processor, carries out the steps of a method for automatic load compensation of an asynchronous machine according to any one of claims 1 to 5.
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| PCT/CN2020/124744 WO2022087951A1 (en) | 2020-10-29 | 2020-10-29 | Automatic load compensation method, apparatus and device for asynchronous electric motor, and medium |
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| CN116846281B (en) * | 2023-07-14 | 2024-06-04 | 郑州轻工业大学 | Asynchronous motor non-speed sensor control method based on magnetic linkage observer with compensation |
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| SU1422352A2 (en) * | 1986-12-24 | 1988-09-07 | Ивановский энергетический институт им.В.И.Ленина | Device for determining coordinates of induction motor in variable electric drive |
| GB2261966B (en) * | 1991-11-30 | 1995-11-08 | Toshiba Kk | Driving control apparatus for induction motor |
| JP3747742B2 (en) * | 2000-05-30 | 2006-02-22 | 株式会社日立製作所 | Constant power operation control method for induction motor |
| CN100586003C (en) * | 2008-10-17 | 2010-01-27 | 清华大学 | Vector control method for speed-free sensor for AC asynchronous motor |
| RU2414806C1 (en) * | 2010-04-23 | 2011-03-20 | Государственное образовательное учреждение высшего профессионального образования "Кузбасский государственный технический университет" (ГУ КузГТУ) | Method of variable-frequency control of electromagnetic moment of asynchronous motor |
| CN102340278A (en) * | 2011-09-30 | 2012-02-01 | 哈尔滨工业大学（威海） | Method for estimating stator flux of motor in vector converter |
| CN103227604A (en) * | 2012-11-01 | 2013-07-31 | 东方日立(成都)电控设备有限公司 | Speed sensorless vector control method for induction motor |
| CN103560735B (en) * | 2013-09-27 | 2014-11-12 | 南车株洲电力机车研究所有限公司 | Control method for electro-magnetic synchronous motor |
| CN111669087B (en) * | 2019-03-08 | 2022-09-23 | 中车大连电力牵引研发中心有限公司 | Asynchronous motor power generation control method and equipment |
| CN109782173B (en) * | 2019-03-25 | 2021-07-16 | 中车青岛四方车辆研究所有限公司 | Asynchronous motor excitation mutual inductance curve measuring system and measuring method thereof |
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