Method and device for acquiring estimated counter electromotive force of non-inductive motor and medium

Abstract

The invention discloses a non-inductive motor estimation counter electromotive force obtaining method and device and a medium, and the method comprises the steps: obtaining the estimation current of a current period based on the input voltage of the current period and the estimation counter electromotive force of a previous period; obtaining a current error of the current period based on the estimated current of the current period and the observed current collected in the current period; acquiring a voltage correction factor of the current period by combining a preset voltage correction factor of the motor based on a magnitude relationship between the current error of the current period and a current error threshold value; based on the voltage correction factor of the current period and the estimated counter electromotive force of the previous period, acquiring the estimated counter electromotive force of the current period; according to the method, the efficiency and the accuracy of obtaining the motor estimated counter electromotive force information in each period are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of control systems, and particularly to a method, device and computer storage medium for obtaining an estimated back electromotive force of a sensorless motor. Background Art

[0002] In the existing sensorless motor FOC control method, information such as the induced electromotive force, rotor speed and position (rotor angle) of the motor is usually obtained based on a sliding mode observer. However, there is often a certain error between the rotor angle information obtained based on the observer and the true value. To improve the accuracy of the rotor angle information, it is often necessary to correct the sliding mode factor calculated from the voltage equation to obtain the estimated back electromotive force information of the motor required for calculating the rotor angle.

[0003] Currently, the sliding mode factor correction method often uses a low-pass filtering method to filter the sliding mode factor; for example, a first-order low-pass filter is used to correct the sliding mode factor. However, due to the filtering parameters included in the low-pass filter, the workload and complexity of parameter adjustment in the estimated back electromotive force correction process are increased; and when the motor reaches a stable state, the estimated back electromotive force value obtained by the low-pass filtering method is approximately equal to the sliding mode factor, approximately equal to 1 / 2 of the actual estimated back electromotive force, and the actual estimated back electromotive force value cannot be directly obtained. When obtaining the estimated back electromotive force of the motor based on the existing estimated back electromotive force correction method, there will be problems such as a complex correction process, low efficiency of obtaining the estimated back electromotive force, and thus low feedback control efficiency of the motor, and the directly obtained estimated back electromotive force value cannot directly describe the actual state of the motor electromotive force. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method, device and computer storage medium for obtaining an estimated back electromotive force of a sensorless motor, which can solve the defects of the existing method for obtaining the estimated back electromotive force of a motor, such as a complex correction process and low efficiency of obtaining the estimated back electromotive force.

[0005] To solve the above technical problems, the present invention first provides a method for obtaining an estimated back electromotive force of a sensorless motor, including: obtaining an estimated current of the current period based on the input voltage of the current period and the estimated back electromotive force of the previous period according to the motor voltage equation; obtaining a current error of the current period based on the estimated current of the current period and the observed current collected in the current period; obtaining a voltage correction factor of the current period based on the magnitude relationship between the current error of the current period and a current error threshold, in combination with a preset voltage correction factor of the motor; and obtaining the estimated back electromotive force of the current period based on the voltage correction factor of the current period and the estimated back electromotive force of the previous period.

[0006] In an embodiment of the present invention, the motor voltage equation is as follows:

[0007]

[0008] where, i s * is the estimated current of the current period, L is the winding inductance, R is the winding resistance, v s is the input voltage of the current period, e s-1 is the estimated back electromotive force of the previous period; s is the number of the current period.

[0009] In an embodiment of the present invention, obtaining the voltage correction factor of the current period based on the magnitude relationship between the current error of the current period and the current error threshold, in combination with the preset voltage correction factor of the motor, includes: obtaining the modulus of the current error of the current period; comparing the magnitude relationship between the modulus of the current error of the current period and the current error threshold; when the modulus of the current error of the current period is less than the current error threshold, correcting the preset voltage correction factor to obtain the voltage correction factor of the current period; otherwise, setting the voltage correction factor of the current period according to the positive or negative of the current error of the current period and the preset voltage correction factor.

[0010] In an embodiment of the present invention, correcting the preset voltage correction factor includes:

[0011] obtaining the ratio between the current error of the current period and the current error threshold, and correcting the preset voltage correction factor based on this ratio, which is:

[0012] z s = K * (Δi s / MaxError)

[0013] where, z s is the voltage correction factor of the current period; Δi s is the current error of the current period; MaxError is the current error threshold; K is the preset voltage correction factor.

[0014] In an embodiment of the present invention, the obtaining method of the estimated back electromotive force of the current period includes:

[0015] superposing the correction factor z n of the current period and the estimated back electromotive force e n-1 of the previous period to obtain the estimated back electromotive force of the current period, which is:

[0016] e s = z s + e s-1

[0017] where z s is the voltage correction factor for the current cycle; e s-1 is the estimated back electromotive force of the previous cycle; e s is the estimated back electromotive force of the current cycle.

[0018] In an embodiment of the present invention, before obtaining the estimated current of the current cycle, the method for obtaining the estimated back electromotive force of the sensorless motor further includes: performing a simulation test on the motor, and determining the preset voltage correction factor of the motor according to the simulation test result, including: determining initial values of a plurality of preset voltage correction factors; respectively performing a simulation test on the motor based on the initial values of the preset voltage correction factors, and obtaining simulation test durations corresponding to the respective initial values; determining a minimum value among the simulation test durations, and setting the initial value of the preset voltage correction factor corresponding to the minimum value as the preset voltage correction factor corresponding to the motor.

[0019] In an embodiment of the present invention, the implementation manner of determining the initial values of the plurality of preset voltage correction factors includes: determining a numerical range interval of the preset voltage correction factor corresponding to the motor based on the performance parameters of the motor; selecting a plurality of numerical values within the numerical range interval as the initial values of the preset voltage correction factors.

[0020] Secondly, the present invention further provides a device for obtaining the estimated back electromotive force of a sensorless motor, including: an estimated current module, configured to obtain the estimated current of the current cycle based on the input voltage of the current cycle and the estimated back electromotive force of the previous cycle according to the motor voltage equation; a current error module, configured to obtain the current error of the current cycle based on the estimated current of the current cycle and the observed current collected in the current cycle; a voltage correction factor module, configured to obtain the voltage correction factor of the current cycle based on the magnitude relationship between the current error of the current cycle and a current error threshold, in combination with the preset voltage correction factor of the motor; an estimated back electromotive force module, configured to obtain the estimated back electromotive force of the current cycle based on the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle.

[0021] In an embodiment of the present invention, the device for obtaining the estimated back electromotive force of the sensorless motor further includes: a preset voltage correction factor module, configured to perform a simulation test on the motor, and determine the preset voltage correction factor of the motor according to the simulation test result, including: determining initial values of a plurality of preset voltage correction factors; respectively performing a simulation test on the motor based on the initial values of the preset voltage correction factors, and obtaining simulation test durations corresponding to the respective initial values; determining a minimum value among the simulation test durations, and setting the initial value of the preset voltage correction factor corresponding to the minimum value as the preset voltage correction factor corresponding to the motor.

[0022] In addition, the present invention further provides a computer storage medium storing a computer program, which when executed by a processor implements the method for obtaining the estimated back electromotive force of the sensorless motor as described above.

[0023] For the method, device and computer storage medium for obtaining the estimated back electromotive force of the sensorless motor provided by the present invention, by obtaining the current error between the estimated current and the measured current in the current period, setting the voltage correction factor in the current period based on the magnitude relationship between the current error obtained in the current period and the current error threshold; and by accumulating the voltage correction factor in the current period and the estimated back electromotive force in the previous period to obtain the estimated back electromotive force in the current period, so that the estimated back electromotive forces in each period approach the true estimated back electromotive force corresponding to that period, which not only improves the acquisition efficiency of the estimated back electromotive force in each period, but also effectively improves the accuracy of the estimated back electromotive force in each period.

[0024] Other features and advantages of the present invention will be described in the following specification, and will become apparent in part from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0026] Figure 1 shows a schematic flow chart of the method for obtaining the estimated back electromotive force of the sensorless motor provided by the present invention in one embodiment;

[0027] Figure 2 shows a schematic flow chart of the method for obtaining the estimated back electromotive force of the sensorless motor provided by the present invention in another embodiment;

[0028] Figure 3 shows a schematic flow chart of step S500 in the present invention in one embodiment;

[0029] Figure 4 shows a schematic structural diagram of the device for obtaining the estimated back electromotive force of the sensorless motor provided by the present invention in one embodiment;

[0030] Figure 5 shows a schematic structural diagram of the device for obtaining the estimated back electromotive force of the sensorless motor provided by the present invention in another embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following will describe the implementation manners of the present invention in detail in combination with the accompanying drawings and embodiments, so as to fully understand how the present invention uses technical means to solve technical problems and the implementation process of achieving technical effects and implement accordingly. It should be noted that as long as there is no conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0032] To solve the technical problems existing in the prior art, the present invention first provides a method for obtaining an estimated back electromotive force of a sensorless motor, which is used to obtain the estimated back electromotive force information of the motor in each simulation cycle.

[0033] Please refer to Figure 1 , which shows a schematic flow chart of the method for obtaining the estimated back electromotive force of the sensorless motor provided by the embodiment of the present invention; as Figure 1 shown, when the method for obtaining the estimated back electromotive force of the sensorless motor executes a single cycle, it includes the following steps:

[0034] S100, based on the input voltage of the current cycle and the estimated back electromotive force of the previous cycle, obtain the estimated current of the current cycle according to the motor voltage equation.

[0035] Specifically, the motor voltage equation is:

[0036]

[0037] wherein, i s * is the estimated current of the current cycle, L is the winding inductance, R is the winding resistance, v s is the input voltage of the current cycle, e s-1 is the estimated back electromotive force of the previous cycle; s is the current cycle number.

[0038] After obtaining the input voltage of the current cycle and the estimated back electromotive force of the previous cycle, input the input voltage of the current cycle and the estimated back electromotive force of the previous cycle into the motor voltage equation, and calculate the estimated current of the current cycle through the motor voltage equation.

[0039] S200, based on the estimated current of the current cycle and the observed current collected in the current cycle, obtain the current error of the current cycle;

[0040] wherein, the observed current is the current value actually output by the motor collected by the observer;

[0041] Specifically, subtract the estimated current of the current cycle from the observed current of the current cycle to obtain the current error of the current cycle, which is:

[0042] Δi s = is * -i s

[0043] where Δi s is the current error in the current cycle; i s * is the estimated current in the current cycle; i s is the observed current in the current cycle.

[0044] S300. Based on the magnitude relationship between the current error in the current cycle and the current error threshold, and in combination with the preset voltage correction factor of the motor, obtain the voltage correction factor for the current cycle;

[0045] Specifically, obtain the modulus value of the current error in the current cycle; compare the magnitude relationship between the modulus value of the current error in the current cycle and the preset current error threshold; according to the comparison result, correct the preset voltage correction factor to obtain the voltage correction factor for the current cycle;

[0046] In a specific embodiment, when the modulus value of the current error in the current cycle is less than the current error threshold, that is:

[0047] |Δi s |<MaxError

[0048] where MaxError is the preset current error threshold;

[0049] Then calculate the ratio between the current error in the current cycle and the current error threshold, and based on this ratio, correct the preset voltage correction factor to obtain the voltage correction factor for the current cycle, which is:

[0050] z s =K*(Δi s / MaxError)

[0051] where z s is the voltage correction factor for the current cycle; K is the preset voltage correction factor.

[0052] When it is detected that the modulus value of the current error in the current cycle is greater than the current error threshold, that is:

[0053] |Δi s |>MaxError

[0054] Then, according to the preset voltage correction factor and the positivity or negativity of the current error in the current cycle, set the voltage correction factor for the current cycle, that is, further detect whether the current error in the current cycle is positive. If so, set the voltage correction factor for the current cycle to be:

[0055] z s = K

[0056] Among them, z s is the voltage correction factor for the current cycle; K is the preset voltage correction factor.

[0057] If not, then set the voltage correction factor for the current cycle to be:

[0058] z s = -K

[0059] S400. Based on the voltage correction factor for the current cycle and the estimated back electromotive force of the previous cycle, obtain the estimated back electromotive force for the current cycle;

[0060] Specifically, add the voltage correction factor z for the current cycle s and the estimated back electromotive force e of the previous cycle s-1 to obtain the estimated back electromotive force for the current cycle, which is:

[0061] e s = z s + e s-1

[0062] Among them, e s-1 is the estimated back electromotive force of the previous cycle; e s is the estimated back electromotive force for the current cycle.

[0063] Return to step S100 and execute the process of obtaining the estimated back electromotive force for the next cycle, that is, repeat the above steps to obtain the estimated back electromotive force for the next cycle.

[0064] In some optional embodiments, before executing step S100, as Figure 2 shown, it further includes:

[0065] S500. Perform a simulation test on the motor and determine the preset voltage correction factor of the motor according to the simulation test results;

[0066] Specifically, when this step is executed, as Figure 3 shown, it includes:

[0067] S501. Determine the initial values of several preset voltage correction factors;

[0068] Based on the performance parameters of the motor, determine the numerical range interval of the preset voltage correction factor corresponding to this motor; select several values in this numerical range interval as the initial values of the preset voltage correction factor.

[0069] S502. Based on the initial values of the preset voltage correction factors, perform motor simulation tests respectively to obtain the simulation test duration corresponding to each initial value.

[0070] Specifically, based on the initial value of a single preset voltage correction factor, perform a simulation test on the motor on a simulation platform; that is, apply an external voltage to the motor, use a signal acquisition tool to collect each current signal output by the motor during the simulation test in real time, and use the method provided in this application to combine the collected current signals to obtain the estimated back electromotive force corresponding to the current signals; based on the collected estimated back electromotive forces, extract the distribution information of the estimated back electromotive force; detect whether the distribution information meets the preset distribution requirements. If so, determine that the simulation process ends, and use the duration corresponding to this simulation process as the simulation duration corresponding to the initial value of the current preset voltage correction factor; if not, continue to perform the simulation test.

[0071] Perform this step for the initial values of all the preset voltage correction factors to obtain the simulation durations corresponding to the initial values of all the preset voltage correction factors.

[0072] In a specific embodiment, the preset distribution requirements include: conforming to a sine curve distribution, having a smooth waveform without abnormalities, and being the same as the frequency of the applied voltage.

[0073] S503. Determine the minimum value of the durations among the simulation test durations, and set the initial value of the preset voltage correction factor corresponding to this minimum duration as the preset voltage correction factor corresponding to the motor.

[0074] To solve the technical problems existing in the prior art, the present invention also provides a device for obtaining the estimated back electromotive force of a sensorless motor, which is used to obtain the estimated back electromotive force information of the motor in each simulation period; please refer to Figure 4 , which shows the structural schematic diagram of the device for obtaining the estimated back electromotive force of the sensorless motor in an embodiment.

[0075] As Figure 4 shown, the device 30 for obtaining the estimated back electromotive force of the sensorless motor includes: an estimated current module 31, a current error module 32, a voltage correction factor module 33, and an estimated back electromotive force module 34.

[0076] Among them, the estimated current module 31 is used to obtain the estimated current of the current period based on the input voltage of the current period and the estimated back electromotive force of the previous period according to the motor voltage equation.

[0077] The current error module 32 is used to obtain the current error of the current period based on the estimated current of the current period and the observed current collected in the current period.

[0078] The voltage correction factor module 33 is configured to obtain the voltage correction factor of the current cycle based on the magnitude relationship between the current error of the current cycle and the current error threshold, in combination with the preset voltage correction factor of the motor;

[0079] The estimated back electromotive force module 34 is configured to obtain the estimated back electromotive force of the current cycle based on the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle.

[0080] In a specific embodiment, the specific implementation manner of obtaining the estimated current of the current cycle according to the input voltage of the current cycle and the estimated back electromotive force of the previous cycle based on the motor voltage equation is the same as that in the above embodiment, and will not be elaborated here.

[0081] In a specific embodiment, the specific implementation manner of obtaining the voltage correction factor of the current cycle based on the magnitude relationship between the current error of the current cycle and the current error threshold, in combination with the preset voltage correction factor of the motor, is the same as that in the above embodiment, and will not be elaborated here.

[0082] In a specific embodiment, the specific implementation manner of obtaining the estimated back electromotive force of the current cycle based on the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle is the same as that in the above embodiment, and will not be elaborated here.

[0083] In some alternative embodiments, the sensorless motor estimated back electromotive force obtaining device is as Figure 5 shown, and further includes: a preset voltage correction factor module 35, which is configured to perform a simulation test on the motor to determine the preset voltage correction factor of the motor according to the simulation test result.

[0084] More specifically, the specific implementation manner of performing a simulation test on the motor to determine the preset voltage correction factor of the motor according to the simulation test result is the same as that in the above embodiment, and will not be elaborated here.

[0085] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is called by a processor, the above-mentioned sensorless motor estimated back electromotive force obtaining method is implemented.

[0086] Among them, a computer-readable storage medium can be a tangible device that can hold and store instructions used by an instruction execution device. The computer-readable storage medium can be, for example, (but is not limited to) an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a memory stick, a floppy disk, and a mechanical coding device.

[0087] The computer-readable programs described herein can be downloaded from the computer-readable storage medium to various computing / processing devices, or downloaded to an external computer or an external storage device through a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network adapter or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0088] In summary, for the method, device, and computer storage medium for obtaining the back electromotive force estimation of the sensorless motor provided by the present invention, a voltage correction factor corresponding to the current cycle is set based on the magnitude relationship between the current error obtained in the current cycle and the current error threshold; and, by accumulating the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle, the accumulated result is used as the estimated back electromotive force obtained in the current cycle, so that the estimated back electromotive forces of each cycle approach the true estimated back electromotive force corresponding to that cycle, and not only improves the acquisition efficiency of the estimated back electromotive force of each cycle, but also effectively improves the accuracy of the estimated back electromotive force of each cycle.

[0089] The above embodiments merely illustrate the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for obtaining the estimated back electromotive force of a sensorless motor, characterized in that, Including: Based on the input voltage of the current cycle and the estimated back electromotive force of the previous cycle, according to the motor voltage equation, obtain the estimated current of the current cycle; Based on the estimated current of the current cycle and the observed current collected in the current cycle, obtain the current error of the current cycle; Based on the magnitude relationship between the current error of the current cycle and the current error threshold, combined with the preset voltage correction factor of the motor, obtain the voltage correction factor of the current cycle; Based on the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle, obtain the estimated back electromotive force of the current cycle.

2. The method for obtaining the estimated back electromotive force of the sensorless motor according to claim 1, wherein The motor voltage equation is: where i s * is the estimated current of the current cycle, L is the winding inductance, R is the winding resistance, v s is the input voltage of the current cycle, e s-1 is the estimated back electromotive force of the previous cycle; s is the current cycle number.

3. The method for obtaining the estimated back electromotive force of the sensorless motor according to claim 1, wherein The method of obtaining the voltage correction factor of the current cycle based on the magnitude relationship between the current error of the current cycle and the current error threshold, combined with the preset voltage correction factor of the motor, includes: Obtain the modulus value of the current error of the current cycle; Compare the magnitude relationship between the modulus value of the current error of the current cycle and the current error threshold; when the modulus value of the current error of the current cycle is less than the current error threshold, correct the preset voltage correction factor to obtain the voltage correction factor of the current cycle; otherwise, set the voltage correction factor of the current cycle according to the positive or negative of the current error of the current cycle and the preset voltage correction factor.

4. The method for obtaining the estimated back electromotive force of the sensorless motor according to claim 3, wherein The correction of the preset voltage correction factor includes: Obtain the ratio between the current error of the current cycle and the current error threshold, and correct the preset voltage correction factor based on this ratio, which is: z s = K * (Δi s / MaxError) where z s is the voltage correction factor for the current cycle; Δi s is the current error for the current cycle; MaxError is the current error threshold; K is a preset voltage correction factor.

5. The method for obtaining the estimated back electromotive force of the sensorless motor according to claim 1, wherein The method of obtaining the estimated back electromotive force of the current cycle includes: Superimpose the voltage correction factor of the current cycle and the estimated back electromotive force of the previous cycle to obtain the estimated back electromotive force of the current cycle, which is: e s = z s + e s-1 Among them, z s is the voltage correction factor for the current cycle; e s-1 is the estimated back electromotive force for the previous cycle; e s is the estimated back electromotive force for the current cycle.

6. The method for obtaining the estimated back electromotive force of the sensorless motor according to claim 1, characterized in that, Before obtaining the estimated current of the current cycle, the method for obtaining the estimated back electromotive force of the sensorless motor further includes: Perform a simulation test on the motor, and determine the preset voltage correction factor of the motor according to the simulation test results, including: Determine the initial values of several preset voltage correction factors; Based on the initial values of each preset voltage correction factor, perform a simulation test on the motor respectively, and obtain the simulation test duration corresponding to each initial value; Determine the minimum value of the duration among the simulation test durations, and set the initial value of the preset voltage correction factor corresponding to this minimum value as the preset voltage correction factor corresponding to the motor.

7. The method for obtaining the estimated back electromotive force of a sensorless motor according to claim 6, wherein The implementation method of determining the initial values of several preset voltage correction factors includes: Based on the performance parameters of the motor, determine the numerical range interval of the preset voltage correction factor corresponding to this motor; Select several values in this numerical range interval as the initial values of the preset voltage correction factor.

8. A device for obtaining the estimated back electromotive force of a sensorless motor, characterized in that, Including: An estimated current module, configured to obtain the estimated current of the current cycle based on the input voltage of the current cycle and the estimated back electromotive force of the previous cycle according to the motor voltage equation; A current error module, configured to obtain the current error of the current cycle based on the estimated current of the current cycle and the observed current collected in the current cycle; A voltage correction factor module, configured to obtain a voltage correction factor for the current cycle based on the magnitude relationship between the current error in the current cycle and a current error threshold, in combination with a preset voltage correction factor of the motor; An estimated back electromotive force module, configured to obtain an estimated back electromotive force for the current cycle based on the voltage correction factor for the current cycle and the estimated back electromotive force for the previous cycle.

9. The back electromotive force estimation acquisition device for the sensorless motor according to claim 8, wherein It further includes: A preset voltage correction factor module, configured to perform a simulation test on the motor and determine the preset voltage correction factor of the motor according to the simulation test results, including: Determining initial values of a plurality of preset voltage correction factors; Based on the initial values of the respective preset voltage correction factors, respectively performing a simulation test on the motor to obtain a simulation test duration corresponding to each initial value; Determining a minimum value among the respective simulation test durations, and setting the initial value of the preset voltage correction factor corresponding to the minimum value as the preset voltage correction factor corresponding to the motor.

10. A computer storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method for obtaining an estimated back electromotive force of a sensorless motor according to any one of claims 1 to 7.

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