Patent Application
20230361702
This application claims priority to Chinese Patent Application No. 202210497318.X filed on May 9, 2022.
The present application relates to motor control technology, in particular to a method for controlling an asynchronous induction motor, a control device for implementing the method, a motor system including the control device, and a computer-readable storage medium on which a computer program for implementing the method is stored.
In most cases, an asynchronous induction motor operates in a non-full load area. At this time, if a variable frequency driver (VFD) still uses the rated magnetic flux to drive the motor, the motor efficiency will be reduced. Therefore, it is necessary to adjust the magnetic flux of the motor dynamically to improve the operation efficiency of the motor without reducing the torque performance.
According to one aspect of the present application, there is provided a method for controlling an asynchronous induction motor, comprising:
Optionally, in the above method, it further comprises:
Optionally, in the above method, the target value of the q-axis current is determined as the minimum value of the q-axis current at a given torque.
Optionally, in the above method, in step A, the target value of the d-axis current is determined to be equal to the target value of the q-axis current.
In addition to one or more of the above features, in the above method, step B comprises:
Optionally, in the above method, in step B2, PI controller or PID controller is used to determine the correction amount of the target value of the d-axis current.
Optionally, in the above method, the preset threshold is the maximum allowable value of the voltage amplitude.
In addition to one or more of the above features, in the above method, step C comprises:
According to another aspect of the present application, there is provided a control device comprising:
According to another aspect of the present application, there is provided a computer-readable storage medium on which a computer program suitable for execution on a processor of a terminal device is stored, and the execution of the computer program causes the steps of the method described above to be executed.
The above and/or other aspects and advantages of the present application will be more clearly and easily understood from the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals. The accompanying drawings include:
The present application is described more fully below with reference to the accompanying drawings, in which illustrative embodiments of the application are illustrated. However, the present application may be implemented in different forms and should not be construed as limited to the embodiments presented herein. The presented embodiments are intended to make the disclosure herein comprehensive and complete, so as to more comprehensively convey the protection scope of the application to those skilled in the art.
In this specification, terms such as “comprising” and “including” mean that in addition to units and steps that are directly and clearly stated in the specification and claims, the technical solution of this application does not exclude the presence of other units and steps that are not directly and clearly stated in the specification and claims.
Unless otherwise specified, terms such as “first” and “second” do not indicate the order of the units in terms of time, space, size, etc., but are merely used to distinguish the units.
Generally speaking, in the d-axis and q-axis steady-state equivalent circuit of an asynchronous induction motor, the influence of magnetic core loss can be expressed in the form of equivalent resistance. After research, the inventor of the application found that the total current flowing through the magnetic core can be minimized by keeping d-axis current ids and q-axis current iqs of the motor consistent, so as to improve the operation efficiency of the motor.
As shown in
Through research, the inventor of the application also found that when the motor operates in the high load area, the stator voltage increases with the increase of d-axis current ids until the d-axis current ids reaches a certain level. This means that after the d-axis current ids reaches this level, even if it increases again, the stator voltage will not increase, resulting in the reduction of motor operation efficiency.
Referring to
For the control of d-axis voltage, as shown in
Referring to
U=√{square root over ((Uj-1d_T)2+(Uj-1q_T)2)} (1a)
Here, U is the voltage amplitude, Uj-1d_T and Uj-1q_T are the target values of d-axis voltage and q-axis voltage at the previous time (e.g. the j−1 time).
It should be noted that the voltage amplitude U of the asynchronous induction motor can also be determined based on the sampling values of d-axis voltage and q-axis voltage at the current time. Exemplarily, the voltage amplitude can be obtained, for example, by the following equation (1b):
U=√{square root over ((Ujd_s)2+(Ujq_s)2)} (1b)
Here, U is the voltage amplitude, Ujd_s and Ujq_s are the sampling values of d-axis voltage and q-axis voltage at the current time (e.g. the j-th time).
Then, the voltage amplitude U is compared with the preset threshold, and the output of PI controller or PID controller or the correction amount Δid of the target value of d-axis current is determined according to the comparison results. The above threshold may be, for example, the maximum allowable value Umax of the voltage amplitude.
When the voltage amplitude is greater than the preset threshold, exemplarily, the correction amount Δid can be determined based on the PI control algorithm shown in the following equation:
Δid=(Umax−U)(kp+ki/S) (2)
Here, Kp is the proportional adjustment coefficient, Ki is the integral adjustment coefficient, and S represents the integral.
On the other hand, when the voltage amplitude is less than or equal to the preset threshold, exemplarily, the correction amount Δid can be determined to be 0.
Thus, the correction value i*d_M of the target value of the d-axis current can be determined as:
i*
d_M
=i*
d
+Δi
d (3)
In the above embodiment, through feedback mechanism based on the voltage amplitude, the flux current can be controlled adaptively, and the motor efficiency can be improved without sacrificing torque performance. In addition, because the control logic does not involve the parameters of the motor, it has strong robustness.
Referring to
Then proceed to step 302. In this step, the motor controller or control unit determines the target value i*d of the d-axis current according to the target value i*q of the q-axis current of the asynchronous induction motor. Exemplarily, based on the Maximum Torque Per Ampere (MTPA) control algorithm, the target value i*d of d-axis current is set equal to the target value i*q of q-axis current.
The flow shown in
Step 401: determine the current voltage amplitude U of the asynchronous induction motor based on the d-axis voltage and q-axis voltage of the asynchronous induction motor. As described above, the d-axis voltage and q-axis voltage can be the sampling values at the current time or the target values determined at the previous time. Exemplarily, the voltage amplitude can be calculated using the above equation (1a) or (1b), for example.
Step 402: judge whether the determined voltage amplitude is greater than the preset threshold (for example, the maximum allowable value Umax of the voltage amplitude). If the voltage amplitude is greater than the preset threshold, proceed to step 403, otherwise proceed to step 404.
Step 403: determine the correction value of the target value of the d-axis current based on the difference between the threshold and the voltage amplitude. For example, the correction value i*d_M may be determined based on the following equation:
i*
d_m
=i*
d(Umax−U)(kp+ki/S) (4)
Step 404: determine the correction amount i*d_M of the target value of the d-axis current as 0.
After performing step 303 or completing the process shown in
Exemplarily, the motor controller or control unit may determine the target values of the q-axis voltage and the d-axis voltage by performing the method steps shown in
Step 501: input a difference between the target value i*q and a sampling value iq of q-axis current to PI controller or PID controller to obtain an adjustment value or target value Uq of the q-axis voltage.
Step 502: input a difference between the correction amount i*d_M of the target value and a sampling value id of d-axis current to PI controller or PID controller to obtain an adjustment value or target value Ud of the d-axis voltage.
It should be noted that steps 501 and 502 shown in
After performing step 304 or completing the process shown in
As shown in
The communication unit 610, as a communication interface, is configured to establish a communication connection between the motor controller or control device and an external device (for example, a variable frequency driver) or a network (for example, the Internet of things).
The memory 620 stores a computer program 640 executable by the processor 630. In addition, the memory 620 may also store data generated when the processor 630 executes the computer program and data received from the external device via the communication unit 610.
The processor 630 is configured to run the computer program 640 stored on the memory 620 and access data on the memory 620 (for example, calling data received from the external devices and storing calculation results such as d-axis and q-axis voltage target values in the memory 620).
The computer program 640 may include computer instructions for implementing the method described by means of
The motor system 700 shown in
For the existing control device (such as motor controller), the above voltage control logic can be implemented only by upgrading the control software running therein, which is beneficial to reduce the cost and shorten the system development time.
According to another aspect of the present application, there is also provided a computer-readable storage medium on which a computer program is stored. When the program is executed by the processor, one or more steps contained in the method described above with the help of
The computer-readable storage medium referred to in the application includes various types of computer storage media, and may be any available medium that can be accessed by a general-purpose or special-purpose computer. For example, the computer-readable storage medium may include RAM, ROM, EPROM, E2PROM, registers, hard disks, removable disks, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other transitory or non-transitory medium that can be used to carry or store a desired program code unit in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. The above combination should also be included in the protection scope of the computer-readable storage medium. An exemplary storage medium is coupled to the processor such that the processor can read and write information from and to the storage medium. In the alternative, the storage medium may be integrated into the processor. The processor and the storage medium may reside in the ASIC. The ASIC may reside in the user terminal. In the alternative, the processor and the storage medium may reside as discrete components in the user terminal.
Those skilled in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described herein can be implemented as electronic hardware, computer software, or combinations of both.
To demonstrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in varying ways for the particular application. However, such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
Although only a few of the specific embodiments of the present application have been described, those skilled in the art will recognize that the present application may be embodied in many other forms without departing from the spirit and scope thereof. Accordingly, the examples and embodiments shown are to be regarded as illustrative and not restrictive, and various modifications may be covered by the application without departing from the spirit and scope of the application as defined by the appended claims.
The embodiments and examples presented herein are provided to best illustrate embodiments in accordance with the present technology and its particular application, and to thereby enable those skilled in the art to make and use the present application. However, those skilled in the art will appreciate that the above description and examples are provided for convenience of illustration and example only. The presented description is not intended to cover every aspect of the application or to limit the application to the precise form disclosed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210497318.X | May 2022 | CN | national |
