Method and device for obtaining back electromotive force coefficient of motor, extractor hood and medium

Abstract

The application discloses a kind of acquisition method, device, range hood and medium of motor back electromotive force coefficient.The acquisition method includes: obtaining the pole pair number and initial back electromotive force coefficient of motor;According to the bus voltage and bus current of the motor collected, the current operating power of motor is calculated;According to the pole pair number and initial back electromotive force coefficient, the flux linkage coefficient of motor is calculated, and the feedback power of motor is calculated based on flux linkage coefficient;According to current operating power and feedback power, the current back electromotive force coefficient is obtained.The current operating power and feedback power of motor are calculated by the application, and the current back electromotive force coefficient is obtained according to the current operating power and feedback power calculated, realizes online dynamic adjustment motor back electromotive force coefficient, so that more accurate back electromotive force coefficient can be obtained;Further, the obtained back electromotive force coefficient is input to observer model, and the rotor position of motor can be obtained more accurately.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically relating to a method, device, range hood, and medium for obtaining the back EMF coefficient of a motor. Background Technology

[0002] During the rotation of a DC motor, it is necessary to know the current position of the rotor in real time. There are generally two common methods for obtaining the rotor position: with or without a position sensor. The former uses a position sensor to collect the current rotor position in real time, while the latter typically uses an observer model. By establishing a variable relationship between the model and the actual rotor and controlling the convergence of that variable, the current position of the motor can be estimated.

[0003] Due to the specific operating conditions of range hoods, such as high temperature and humidity, and the presence of oil fumes and moisture, the lifespan of motor drive solutions with position sensors is often not guaranteed. Therefore, variable frequency drive motors for range hoods often employ a sensorless—observer model to obtain the motor's current position. When building the mathematical theoretical model of the motor, the input parameters of the motor itself are indispensable. Commonly used motor parameters include resistance, inductance, and back EMF constant. These parameters often change with the temperature of the motor itself.

[0004] There are two methods for measuring motor parameters in the existing technology. The first method adopts offline measurement, which involves creating a parameter-temperature change curve and then measuring the parameters by looking up a table. This method has the problem that the motor parameters are fixed and cannot be adjusted. The second method adopts online measurement, which involves creating a parameter-running time change curve and simulating the approximate temperature based on the running time, thereby adjusting the parameters. Although this method solves the problem of fixed parameters that cannot be adjusted, it also has the problem of not being able to accurately adjust the motor parameters online. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art in that it is impossible to accurately adjust the motor parameters online, and to provide a method, device, range hood and medium for obtaining the back EMF coefficient of a motor.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] In a first aspect, the present invention provides a method for obtaining the back electromotive force coefficient of a motor, the method comprising:

[0008] Obtain the number of pole pairs and the initial back EMF coefficient of the motor;

[0009] The current operating power of the motor is calculated based on the collected bus voltage and bus current of the motor.

[0010] The flux linkage coefficient of the motor is calculated based on the number of pole pairs and the initial back EMF coefficient, and the feedback power of the motor is calculated based on the flux linkage coefficient.

[0011] The current back EMF coefficient is obtained based on the current operating power and the feedback power.

[0012] Preferably, the step of calculating the feedback power of the motor based on the flux linkage coefficient includes:

[0013] Obtain the heating power of the motor;

[0014] The output power of the motor is calculated based on the flux linkage coefficient;

[0015] The feedback power of the motor is calculated based on the heating power and the output power.

[0016] Preferably, the step of calculating the output power of the motor based on the flux linkage coefficient includes:

[0017] Obtain the direct-axis inductance, quadrature-axis inductance, direct-axis current, and quadrature-axis current of the motor;

[0018] The output power of the motor is calculated based on the flux linkage coefficient, the direct-axis inductance, the quadrature-axis inductance, the direct-axis current, and the quadrature-axis current.

[0019] Preferably, the direct-axis inductance of the motor is equal to its quadrature-axis inductance.

[0020] Preferably, the step of calculating the feedback power of the motor based on the heating power and the output power includes:

[0021] The feedback power is calculated based on the heating power and the output power using a control strategy where the direct-axis current of the motor is zero.

[0022] Preferably, the step of obtaining the current back EMF coefficient based on the current operating power and the feedback power includes:

[0023] The difference between the current operating power and the feedback power is subjected to PI processing to obtain the current back EMF coefficient.

[0024] Preferably, the acquisition method further includes:

[0025] The current back EMF coefficient is input into the observer model for calculation to obtain the rotor position of the motor.

[0026] Secondly, the present invention provides a device for obtaining the back electromotive force coefficient of a motor, the device comprising:

[0027] The data acquisition module is used to acquire the number of pole pairs and the initial back EMF coefficient of the motor.

[0028] The current operating power calculation module is used to calculate the current operating power of the motor based on the collected bus voltage and bus current of the motor.

[0029] The feedback power calculation module is used to calculate the flux linkage coefficient of the motor based on the number of pole pairs and the initial back EMF coefficient, and to calculate the feedback power of the motor based on the flux linkage coefficient.

[0030] The back EMF coefficient acquisition module is used to acquire the current back EMF coefficient based on the current operating power and the feedback power.

[0031] Thirdly, the present invention provides a range hood, including a motor, a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for obtaining the back EMF coefficient of the motor according to the present invention.

[0032] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for obtaining the back EMF coefficient of a motor according to the present invention.

[0033] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0034] The positive and progressive effects of this invention are as follows: This invention designs a method for obtaining the back EMF coefficient of a motor. This method calculates the current operating power and feedback power of the motor, and obtains the current back EMF coefficient based on the calculated current operating power and feedback power, thereby realizing online dynamic adjustment of the back EMF coefficient of the motor, thus obtaining a more accurate back EMF coefficient; furthermore, by inputting the obtained back EMF coefficient into the observer model, a more accurate rotor position of the motor can be obtained. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the method for obtaining the back EMF coefficient of a motor provided in Example 1.

[0036] Figure 2 This is a schematic diagram illustrating the application of the method for obtaining the back EMF coefficient of a motor provided in Example 1.

[0037] Figure 3 This is a schematic diagram of the module for obtaining the back EMF coefficient of a motor provided in Example 2.

[0038] Figure 4 This is a schematic diagram of the range hood provided in Example 3. Detailed Implementation

[0039] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0040] Example 1

[0041] This embodiment provides a method for obtaining the back EMF coefficient of a motor, such as... Figure 1 and 2 As shown, the acquisition method includes:

[0042] Step S1: Obtain the number of pole pairs and the initial back EMF coefficient of the motor.

[0043] In this embodiment, the number of pole pairs P and the initial back EMF coefficient K of the motor are tested in advance using external metering equipment. e0 The back EMF coefficient can be defined as: the effective value of the stator line voltage when the motor rotates at 1000 RPM under open-circuit conditions, denoted as K. e (V / KRPM); Specifically, the back electromotive force coefficient K can be calculated using the following formula. e :

[0044]

[0045] In the formula, P represents the number of pole pairs, T represents the period of the test voltage waveform, and V pp This indicates the peak-to-peak value of the line voltage.

[0046] Step S2: Calculate the current operating power of the motor based on the collected bus voltage and bus current of the motor.

[0047] In this embodiment, when calculating the current operating power of the motor, it is necessary to first collect the motor winding bus voltage V. bus and bus current I bus The current operating power of the motor, Power, is calculated using the following formula. ref :

[0048] Power ref =V bus *I bus

[0049] Step S3: Calculate the flux linkage coefficient of the motor based on the number of pole pairs and the initial back EMF coefficient, and calculate the feedback power of the motor based on the flux linkage coefficient.

[0050] In this embodiment, the flux linkage coefficient of the motor is calculated based on the pre-measured number of pole pairs and the initial back EMF coefficient. Specifically, the back EMF amplitude E and the electric angular velocity ω of the motor are obtained. rThe flux linkage coefficient of the motor is calculated by the ratio of the two. The back EMF of the motor can be defined as the effective value of the linear back EMF, and therefore the amplitude E of the back EMF and the electric angular velocity ω of the motor can be calculated using the following formulas. r and the magnetic flux coefficient of the motor

[0051]

[0052] ω r =2Π*n*P / 60

[0053]

[0054] In the formula, P represents the pole logarithm, and K e0 This represents the initial back electromotive force coefficient.

[0055] As an optional embodiment, the step of calculating the feedback power of the motor based on the flux linkage coefficient includes: obtaining the heating power of the motor; calculating the output power of the motor based on the flux linkage coefficient; and calculating the feedback power of the motor based on the heating power and the output power.

[0056] In this embodiment, the operating power of the motor can be equivalent to the sum of the motor's heat generation power and output power. Therefore, the feedback power of the motor can be calculated based on the motor's heat generation power and output power. Specifically, since the motor windings can theoretically be equivalent to resistance, the motor's heat generation power P... cu It can be calculated using the following formula:

[0057] P cu =i s 2 *R s

[0058] In the formula, R s i represents the equivalent resistance of the motor. s This represents the current passing through the equivalent resistance.

[0059] As an optional embodiment, the step of calculating the motor's output power based on the flux linkage coefficient includes: obtaining the motor's direct-axis inductance, quadrature-axis inductance, direct-axis current, and quadrature-axis current; and calculating the motor's output power based on the flux linkage coefficient, direct-axis inductance, quadrature-axis inductance, direct-axis current, and quadrature-axis current. Specifically, the output power can be calculated using the following formula:

[0060]

[0061] In the formula, L represents the flux linkage coefficient. d L represents direct-axis inductance. q Indicates quadrature axis inductance, i d i represents the direct-axis current.q This represents the quadrature-axis current.

[0062] As an optional embodiment, when the motor is used in a range hood, a surface-mount motor can be used. Surface-mount motors have the characteristic that the direct-axis inductance and quadrature-axis inductance of the motor are equal. Other types of motors can also be used. This is only an example and is not a specific limitation.

[0063] As an optional embodiment, the step of calculating the motor's feedback power based on the heating power and output power includes: using a control strategy where the motor's direct-axis current is zero to calculate the feedback power based on the heating power and output power. Specifically, the motor's feedback power based on the heating power and output power can be calculated using the following formula:

[0064]

[0065] when i d When = 0, i s =i q Therefore, the feedback power Power can be calculated using the following formula. fed :

[0066]

[0067] In the formula, Represents the flux linkage coefficient, P represents the number of pole pairs, and i q R represents the quadrature-axis current. s This represents the equivalent resistance of the motor.

[0068] Step S4: Obtain the current back EMF coefficient based on the current operating power and feedback power.

[0069] In this embodiment, this step can obtain the current back EMF coefficient by performing PI processing on the difference between the current operating power and the feedback power. Specifically, the difference between the calculated current operating power and the feedback power is calculated and passed through a PI controller to perform PI processing on the difference between the two, so that the feedback power approximates the current operating power, thereby obtaining the current back EMF coefficient of the motor. Here, performing PI processing on the difference is just an example. Other types of processing can also be performed on the difference, such as PID processing, fuzzy control processing, etc., to obtain the back EMF coefficient. No specific limitation is made here.

[0070] As an optional embodiment, the method for obtaining the back EMF coefficient of the motor further includes inputting the current back EMF coefficient into the observer model for calculation to obtain the position of the motor rotor.

[0071] This embodiment discloses a method for obtaining the back EMF coefficient of a motor. This method calculates the current operating power and feedback power of the motor, and obtains the current back EMF coefficient based on the calculated current operating power and feedback power, thereby realizing online dynamic adjustment of the back EMF coefficient of the motor, thus obtaining a more accurate back EMF coefficient. Furthermore, by inputting the obtained back EMF coefficient into the observer model, a more accurate rotor position of the motor can be obtained.

[0072] Example 2

[0073] This embodiment provides a device for obtaining the back EMF coefficient of a motor, such as... Figure 3 As shown, the acquisition device includes a data acquisition module 11, a current operating power calculation module 12, a feedback power calculation module 13, and a back EMF coefficient acquisition module 14.

[0074] The data acquisition module 11 is used to acquire the number of pole pairs of the motor and the initial back EMF coefficient.

[0075] In this embodiment, the data acquisition module 11 obtains the number of pole pairs P and the initial back EMF coefficient K of the motor in advance using an external metering device. e0 The back EMF coefficient can be defined as: the effective value of the stator line voltage when the motor rotates at 1000 RPM under open-circuit conditions, denoted as K. e (V / KRPM); Specifically, the back electromotive force coefficient K can be calculated using the following formula. e :

[0076]

[0077] In the formula, P represents the number of pole pairs, T represents the period of the test voltage waveform, and V pp This indicates the peak-to-peak value of the line voltage.

[0078] The current operating power calculation module 12 is used to calculate the current operating power of the motor based on the collected bus voltage and bus current of the motor.

[0079] In this embodiment, when calculating the current operating power of the motor, the current operating power calculation module 12 needs to first collect the motor winding bus voltage V. bus and bus current I bus The current operating power of the motor, Power, is calculated using the following formula. ref :

[0080] Power ref =V bus *I bus

[0081] The feedback power calculation module 13 is used to calculate the flux linkage coefficient of the motor based on the number of pole pairs and the initial back EMF coefficient, and to calculate the feedback power of the motor based on the flux linkage coefficient.

[0082] In this embodiment, the feedback power calculation module 13 calculates the flux linkage coefficient of the motor based on the pre-measured number of pole pairs and the initial back EMF coefficient. Specifically, the feedback power calculation module 13 obtains the back EMF amplitude E and the electric angular velocity ω of the motor. r The motor flux linkage coefficient is calculated by the ratio of the two; where the motor back EMF can be defined as the effective value of the line back EMF, so the feedback power calculation module 13 can calculate the motor back EMF amplitude E and the motor electric angular velocity ω by the following formula. r and the magnetic flux coefficient of the motor

[0083]

[0084]

[0085]

[0086] In the formula, P represents the pole logarithm, and K e0 This represents the initial back electromotive force coefficient.

[0087] As an optional embodiment, the step of the feedback power calculation module 13 in calculating the feedback power of the motor based on the flux linkage coefficient includes: obtaining the heating power of the motor; calculating the output power of the motor based on the flux linkage coefficient; and calculating the feedback power of the motor based on the heating power and the output power.

[0088] In this embodiment, the operating power of the motor can be equivalent to the sum of the motor's heat generation power and output power. Therefore, the feedback power calculation module 13 can calculate the motor's feedback power based on the motor's heat generation power and output power. Specifically, since the motor's windings can theoretically be equivalent to resistance, the motor's heat generation power P... cu It can be calculated using the following formula:

[0089] P cu =i s 2 *R s

[0090] In the formula, R s i represents the equivalent resistance of the motor. s This represents the current passing through the equivalent resistance.

[0091] As an optional embodiment, the step of the feedback power calculation module 13 in calculating the motor's output power based on the flux linkage coefficient includes: obtaining the motor's direct-axis inductance, quadrature-axis inductance, direct-axis current, and quadrature-axis current; and calculating the motor's output power based on the flux linkage coefficient, direct-axis inductance, quadrature-axis inductance, direct-axis current, and quadrature-axis current. Specifically, the output power can be calculated using the following formula:

[0092]

[0093] In the formula, L represents the flux linkage coefficient. d L represents direct-axis inductance. q Indicates quadrature axis inductance, i d i represents the direct-axis current. q This represents the quadrature-axis current.

[0094] As an optional embodiment, when the motor is used in a range hood, a surface-mount motor can be used. Surface-mount motors have the characteristic that the direct-axis inductance and quadrature-axis inductance of the motor are equal. Other types of motors can also be used. This is only an example and is not a specific limitation.

[0095] As an optional embodiment, the step of the feedback power calculation module 13 in calculating the motor's feedback power based on the heating power and output power includes: using a control strategy where the motor's direct-axis current is zero to calculate the feedback power based on the heating power and output power. Specifically, the motor's feedback power can be calculated using the following formula:

[0096]

[0097] when i d When = 0, i s =i q Therefore, the feedback power can be calculated using the following formula:

[0098]

[0099] In the formula, Represents the flux linkage coefficient, P represents the number of pole pairs, and i q R represents the quadrature-axis current. s This represents the equivalent resistance of the motor.

[0100] The back EMF coefficient acquisition module 14 is used to acquire the current back EMF coefficient based on the current operating power and the feedback power.

[0101] In this embodiment, the back EMF coefficient acquisition module 14 can obtain the current back EMF coefficient by performing PI processing on the difference between the current operating power and the feedback power. Specifically, the back EMF coefficient acquisition module 14 calculates the difference between the calculated current operating power and the feedback power, and passes the difference through a PI controller to perform PI processing on the difference between the two, so that the feedback power approximates the current operating power, thereby obtaining the current back EMF coefficient of the motor. Here, performing PI processing on the difference is just an example. Other types of processing can also be performed on the difference, such as PID processing, fuzzy control processing, etc., to obtain the back EMF coefficient. No specific limitation is made here.

[0102] This embodiment discloses a device for obtaining the back EMF coefficient of a motor. This device is based on the method for obtaining the back EMF coefficient of a motor provided in Embodiment 1 of the present invention. This device realizes online dynamic adjustment of the back EMF coefficient of the motor, and can obtain a more accurate back EMF coefficient.

[0103] Example 3

[0104] This embodiment provides a range hood, which includes a motor, a memory, a processor, and a computer program stored in the memory and used to run on the processor. When the processor executes the program, it implements the method for obtaining the back EMF coefficient of the motor in Embodiment 1 above.

[0105] like Figure 4 The range hood 30 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention.

[0106] The range hood 30 can be represented in the form of a general computing device, such as a server device. The components of the range hood 30 may include, but are not limited to: at least one processor 31, at least one memory 32, and a bus 33 connecting different system components (including memory 32 and processor 31).

[0107] Bus 33 includes a data bus, an address bus, and a control bus.

[0108] The memory 32 may include volatile memory, such as random access memory (RAM) 321 and cache memory 322, and may further include read-only memory (ROM) 323.

[0109] The memory 32 may also include a program tool 325 having a set (at least one) of program modules 324, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0110] The processor 31 executes various functional applications and data processing by running computer programs stored in the memory 32, such as the method for obtaining the back EMF coefficient of a motor in Embodiment 1 of the present invention.

[0111] The range hood 30 can also communicate with one or more external devices 34. This communication can be achieved through the input / output (I / O) interface 35. Furthermore, the model-generating device 30 can also communicate with one or more networks via a network adapter 36. Figure 4 As shown, network adapter 36 communicates with other modules of the model-generating device 30 via bus 33. It should be understood that, although... Figure 4 Unless otherwise specified, the device 30 generated in conjunction with the model may use other hardware and / or software modules, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0112] It should be noted that although several units / modules or sub-units / modules of the range hood have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0113] Example 4

[0114] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for obtaining the back EMF coefficient of a motor as described in Embodiment 1 above.

[0115] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0116] In an alternative embodiment, the present invention can also be implemented as a program product, which includes program code. When the program product is run on a terminal device, the program code is used to cause the terminal device to execute the method for obtaining the back EMF coefficient of the motor as described in Embodiment 1 above.

[0117] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for obtaining back EMF coefficient of an electric machine, characterized in that, The acquisition method comprises: acquiring the pole pair number and the initial back electromotive force coefficient of the motor; calculating the current operating power of the motor according to the bus voltage and the bus current of the motor collected; calculating the flux linkage coefficient of the motor according to the pole pair number and the initial back electromotive force coefficient, and calculating the feedback power of the motor based on the flux linkage coefficient; acquiring the current back electromotive force coefficient according to the current operating power and the feedback power; the step of calculating the feedback power of the motor based on the flux linkage coefficient comprises: acquiring the heating power of the motor; calculating the output power of the motor based on the flux linkage coefficient; calculating the feedback power of the motor according to the heating power and the output power; the step of calculating the output power of the motor based on the flux linkage coefficient comprises: acquiring the direct-axis inductance, the quadrature-axis inductance, the direct-axis current and the quadrature-axis current of the motor; calculating the output power of the motor according to the flux linkage coefficient, the direct-axis inductance, the quadrature-axis inductance, the direct-axis current and the quadrature-axis current.

2. The method of claim 1, wherein the method further comprises: The direct-axis inductance of the motor is equal to the quadrature-axis inductance.

3. The method of claim 1, wherein the method further comprises: the step of calculating the feedback power of the motor according to the heating power and the output power comprises: calculating the feedback power according to the heating power and the output power by using the control strategy that the direct-axis current of the motor is zero.

4. The method of claim 1, wherein the method further comprises: the step of acquiring the current back electromotive force coefficient according to the current operating power and the feedback power comprises: performing PI processing on the difference between the current operating power and the feedback power to acquire the current back electromotive force coefficient.

5. The method of claim 1-4, wherein, the acquisition method further comprises: inputting the current back electromotive force coefficient into an observer model to calculate the rotor position of the motor.

6. A device for obtaining the back electromotive force coefficient of a motor, characterized in that, The acquisition device comprises: a data acquisition module for acquiring the pole pair number and the initial back electromotive force coefficient of the motor; a current operating power calculation module for calculating the current operating power of the motor according to the bus voltage and the bus current of the motor collected; a feedback power calculation module for calculating the flux linkage coefficient of the motor according to the pole pair number and the initial back electromotive force coefficient, and calculating the feedback power of the motor based on the flux linkage coefficient; a back electromotive force coefficient acquisition module for acquiring the current back electromotive force coefficient according to the current operating power and the feedback power; the step of calculating the feedback power of the motor based on the flux linkage coefficient by the feedback power calculation module comprises: acquiring the heating power of the motor; calculating the output power of the motor based on the flux linkage coefficient; calculating the feedback power of the motor according to the heating power and the output power; the step of calculating the output power of the motor based on the flux linkage coefficient by the feedback power calculation module comprises: acquiring the direct-axis inductance, the quadrature-axis inductance, the direct-axis current and the quadrature-axis current of the motor; calculating the output power of the motor according to the flux linkage coefficient, the direct-axis inductance, the quadrature-axis inductance, the direct-axis current and the quadrature-axis current.

7. An extractor hood comprising a motor, a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the acquisition method of the back electromotive force coefficient of the motor as claimed in any one of claims 1-5 when executing the computer program.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program implements the acquisition method of the back electromotive force coefficient of the motor as claimed in any one of claims 1-5 when executed by the processor.

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