Modulation method, apparatus and electronic device for pulse width modulation carrier

Abstract

The embodiment of the present application provides a kind of modulation method, device and electronic equipment of pulse width modulation carrier, by obtaining the resonant frequency of frequency converter, resonant frequency is the frequency corresponding to the resonance point when producing resonance in the use process of frequency converter;According to the target carrier period of resonant frequency determination;Control the motor current output in target carrier period, so that the pulse width modulation carrier obtained in target carrier period is sine wave.The technical scheme provided by the embodiment of the present application modulates the motor current output according to the resonant frequency of frequency converter, so that the pulse width modulation carrier obtained in target carrier period is sine wave, can effectively eliminate the noise generated by the resonance of pulse width modulation carrier and other structural parts, reduce the influence of noise on motor control.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and in particular to a modulation method, apparatus and electronic device for pulse width modulation carrier. Background Technology

[0002] Variable-frequency drives (VFDs), as commonly used power control devices, utilize frequency conversion and microelectronic technologies to control AC motors by changing the frequency of the motor's power supply. However, during the use of VFDs, the magnetic field generated by the higher harmonics in the output waveform can produce electromagnetic forces on many mechanical components. The frequency of these forces may be close to or coincide with the natural frequency of some mechanical components, leading to resonance and thus generating noise.

[0003] Currently, noise generated during the operation of frequency converters can be reduced using vector control. Specifically, by controlling the magnitude and phase of the motor stator current through a vector coordinate circuit, the excitation current and torque current of the motor in each coordinate axis system can be controlled separately, thereby controlling the motor torque. By controlling the sequence and timing of the action of each vector, as well as the duration of the zero vector, a pulse width modulation (PWM) carrier with the fewest switching operations is formed to reduce switching losses.

[0004] Since the noise generated during the operation of a frequency converter is mainly due to the resonance between the PWM carrier and the system composed of the motor and its structural components, the PWM carrier with the fewest switching cycles obtained through vector control cannot eliminate the noise generated by the resonance. Therefore, how to eliminate the noise generated by the resonance between the PWM carrier and the motor and its structural components is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides a method, apparatus, and electronic device for modulating a pulse width modulation carrier, which can obtain a sinusoidal pulse width modulation carrier within the template carrier period and effectively eliminate noise generated by resonance between the PWM carrier and the motor and its structural components.

[0006] In a first aspect, embodiments of this application provide a modulation method for a pulse width modulation carrier, the modulation method for the pulse width modulation carrier comprising:

[0007] The resonant frequency of the frequency converter is obtained, which is the frequency corresponding to the resonance point when the frequency converter generates resonance during operation.

[0008] The target carrier period is determined based on the resonant frequency;

[0009] The motor current is controlled to be output within the target carrier period so that the pulse width modulation carrier obtained within the target carrier period is a sine wave.

[0010] Optionally, determining the target carrier period based on the resonant frequency includes:

[0011] According to the formula Determine the target carrier period;

[0012] Where Tp is the target carrier period and fn is the resonance frequency.

[0013] Optionally, the target carrier period is a preset number of times the control period of the motor current, and the preset number is an even number greater than 4.

[0014] Optionally, the method further includes:

[0015] Based on the motor current output within the target carrier period, the carrier frequency of the pulse width modulation carrier corresponding to the motor current is obtained;

[0016] Calculate the similarity between the distribution of the carrier frequency within the target carrier period and a preset sinusoidal distribution;

[0017] If the similarity is less than a preset similarity threshold, the currently used preset quantity is updated, and the motor current is output in the new target carrier period corresponding to the new preset quantity.

[0018] Optionally, updating the currently used preset quantity includes:

[0019] For even numbers greater than 4, the values ​​other than the currently used preset quantity will be determined as the new preset quantity.

[0020] Optionally, the preset sinusoidal distribution is the distribution of a carrier centered at a preset frequency within the target carrier period, and the preset frequency is half of the sum of the maximum and minimum carrier frequencies allowed by the motor for pulse width modulation.

[0021] Secondly, embodiments of this application provide a modulation apparatus for a pulse width modulation carrier, the modulation apparatus comprising:

[0022] The acquisition module is used to acquire the resonant frequency of the frequency converter, which is the frequency corresponding to the resonance point when the frequency converter generates resonance during operation.

[0023] The processing module is used to determine the target carrier period based on the resonant frequency;

[0024] The output module is used to control the output of motor current during the target carrier period so that the pulse width modulation carrier obtained during the target carrier period is a sine wave.

[0025] Optionally, the processing module is specifically used to process according to the formula. Determine the target carrier period; where Tp is the target carrier period and fn is the resonant frequency.

[0026] Optionally, the target carrier period is a preset number of times the control period of the motor current, and the preset number is an even number greater than 4.

[0027] Optionally, the device further includes an update module, which is used to obtain the carrier frequency of the pulse width modulation carrier corresponding to the motor current based on the motor current output in the target carrier period; calculate the similarity between the distribution of the carrier frequency in the target carrier period and a preset sinusoidal distribution; when the similarity is less than a preset similarity threshold, update the currently used preset quantity, and output the motor current in the new target carrier period corresponding to the new preset quantity.

[0028] Optionally, the update module is specifically used to determine a new preset quantity for even numbers greater than 4, excluding the currently used preset quantity.

[0029] Optionally, the preset sinusoidal distribution is the distribution of a carrier centered at a preset frequency within the target carrier period, and the preset frequency is half of the sum of the maximum and minimum carrier frequencies allowed by the motor for pulse width modulation.

[0030] Thirdly, embodiments of this application also provide an electronic device, which includes: a processor and a memory communicatively connected to the processor;

[0031] The memory stores computer-executed instructions;

[0032] The processor executes computer execution instructions stored in the memory to implement the method described in any possible implementation of the first aspect above.

[0033] Fourthly, embodiments of this application also provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the method described in any possible implementation of the first aspect.

[0034] Fifthly, embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the method described in any possible implementation of the first aspect.

[0035] Therefore, this application provides a method, apparatus, and electronic device for modulating a pulse width modulation (PWM) carrier wave. The method involves acquiring the resonant frequency of the frequency converter (the frequency corresponding to the resonance point during inverter operation), determining the target carrier period based on the resonant frequency, and controlling the output motor current within the target carrier period to ensure that the PWM carrier wave obtained within the target carrier period is a sine wave. The technical solution provided by this application modulates the output motor current based on the frequency converter's resonant frequency, ensuring that the PWM carrier wave obtained within the target carrier period is a sine wave. This effectively eliminates noise generated by resonance between the PWM carrier wave and other structural components, improves the user experience, and effectively avoids the impact of noise on motor control. Attached Figure Description

[0036] Figure 1 A schematic diagram of the operation of a frequency converter driving a motor in the prior art is provided for an embodiment of this application;

[0037] Figure 2 A schematic flowchart illustrating a modulation method for a pulse width modulation carrier provided in an embodiment of this application;

[0038] Figure 3 This application provides a schematic diagram of the distribution of a PWM carrier within a target carrier period, as illustrated in an embodiment of the present application.

[0039] Figure 4 This is a schematic diagram of the structure of a modulation device for a pulse width modulation carrier provided in an embodiment of this application;

[0040] Figure 5 This is a schematic diagram of an electronic device structure provided in this application.

[0041] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0043] In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0044] The technical solution provided in this application can be applied to scenarios involving vibration and noise elimination. When the inverter drives the motor, multiple electronic switching devices can be appropriately switched on and off using an externally input DC or AC power supply to generate three-phase AC power. The generated three-phase AC power is then applied to the motor stator to generate a rotating magnetic field. This rotating magnetic field produces a torque in the motor rotor that is in the same direction as the rotation of the rotating magnetic field, causing it to drive the load to rotate.

[0045] To reduce the noise generated when the inverter drives the motor, it is possible to... Figure 1 The structure shown controls the motor. Figure 1 This is a schematic diagram illustrating the operation of a frequency converter driving a motor in the prior art, provided as an embodiment of this application. According to... Figure 1 As shown, a high-performance motor drive algorithm, such as vector control, is used to generate a torque command. This torque command is then used to generate a PWM carrier wave, which is used to control the on / off state of electronic switching devices to generate a rotating magnetic field corresponding to the torque command, thereby controlling the motor to drive the load to rotate. Figure 1 The structure shown can effectively reduce the loss of the switch, thereby eliminating some of the noise generated by the switching on and off.

[0046] However, the main cause of noise in the inverter control circuit is the resonance between the PWM carrier and the system composed of the motor and its structural components. Figure 1 The structure shown cannot eliminate the noise generated by resonance. Therefore, how to eliminate the noise generated by the resonance between the PWM carrier and the motor and its structural components is a technical problem that urgently needs to be solved by those skilled in the art.

[0047] To eliminate noise caused by resonance, the target carrier period can be obtained based on the resonant frequency of the inverter. This allows the PWM carrier obtained within the target carrier period to be a sine wave, thus achieving modulation of the PWM carrier. This results in a more dispersed distribution of the PWM carrier within the target carrier period, effectively suppressing vibration and noise caused by high-frequency subcarriers. Consequently, the noise generated by the resonance of structural components in the inverter is eliminated, achieving the level of white noise.

[0048] The modulation method for the pulse width modulation carrier provided in this application will now be described in detail through specific embodiments. It is understood that the following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0049] Figure 2 This is a flowchart illustrating a pulse width modulation (PWM) carrier modulation method provided in an embodiment of this application. The PWM carrier modulation method can be executed by software and / or hardware devices. For example, the hardware device can be a PWM carrier modulation apparatus, which can be a terminal or a processing chip within the terminal. For example, please refer to [link to example]. Figure 2 As shown, the modulation method for this pulse width modulation carrier may include:

[0050] S201. Obtain the resonant frequency of the frequency converter, wherein the resonant frequency is the frequency corresponding to the resonance point when the frequency converter generates resonance during use.

[0051] For example, when obtaining the resonant frequency of a frequency converter, the resonant point can be detected using a detection device such as an oscilloscope during the operation of the frequency converter, and the resonant frequency corresponding to the resonant point can be obtained. This application does not limit the specific method for obtaining the resonant frequency.

[0052] S202. Determine the target carrier period based on the resonance frequency.

[0053] For example, when determining the target carrier period based on the resonant frequency, the target carrier period can be determined according to the following formula (1):

[0054]

[0055] In the above formula (1), Tp is the target carrier period and fn is the resonance frequency.

[0056] It is understandable that the target carrier period can be a variable period of the PWM carrier, that is, the period corresponding to the modulated PWM carrier.

[0057] In this embodiment, the target carrier period is determined based on the resonant frequency, making the determined target carrier period more accurate. This allows the PWM carrier to be modulated based on the resonant frequency, thereby improving the noise reduction effect and achieving the effect of white noise.

[0058] For example, the target carrier period is a preset number of times the motor current control period, and the preset number is an even number greater than 4. For instance, the target carrier period can be 4, 6, or 8 times the motor current control period, and the specific value can be set according to the actual situation of the frequency converter. This application embodiment does not impose any limitation on this.

[0059] In this embodiment of the application, by setting the target carrier period to a preset number of times the control period of the motor current, the accuracy of the determined target carrier period can be further improved, thereby improving the noise elimination effect.

[0060] After determining the target carrier period, the following step S203 can be performed based on the determined target carrier period:

[0061] S203. Control the output motor current within the target carrier period so that the pulse width modulation carrier obtained within the target carrier period is a sine wave.

[0062] For example, when controlling the output motor current within a target carrier cycle, the preset number of motor current cycles corresponding to the preset number output within one target carrier cycle can be used, based on the preset number in the above steps, so that the pulse width modulation carrier obtained within the target carrier cycle is a sine wave. That is, the envelope formed by the PWM carrier within the target carrier cycle is the envelope corresponding to the sine wave.

[0063] Therefore, the pulse width modulation carrier modulation method provided in this application obtains the resonant frequency of the frequency converter, which is the frequency corresponding to the resonance point when resonance occurs during the operation of the frequency converter; determines the target carrier period based on the resonant frequency; and controls the output of motor current within the target carrier period so that the pulse width modulation carrier obtained within the target carrier period is a sine wave. The technical solution provided in this application obtains the target carrier period based on the resonant frequency of the frequency converter, enabling the output of motor current within the target carrier period and obtaining a sine wave pulse width modulation wave, thereby eliminating noise generated by resonance during the operation of the frequency converter. Since it is determined based on the resonant frequency, the noise cancellation effect is improved.

[0064] In another embodiment of this application, when controlling the output of motor current within the target carrier period, the noise cancellation effect can be detected in real time. For example, the carrier frequency of the pulse width modulation carrier corresponding to the motor current can be obtained based on the output motor current within the target carrier period; the similarity between the distribution of the carrier frequency within the target carrier period and the preset sinusoidal distribution can be calculated; if the similarity is less than the preset similarity threshold, the currently used preset quantity is updated, and the motor current is output within the new target carrier period corresponding to the new preset quantity.

[0065] For example, the preset sinusoidal distribution is a sinusoidal distribution corresponding to the distribution of the carrier frequency within the target carrier period, but this application embodiment does not impose any limitation on it.

[0066] It is understandable that the closer the carrier frequency distribution within the target carrier period is to a sinusoidal distribution, the better the noise reduction effect on the frequency converter. Therefore, when the similarity is a percentage, the preset similarity threshold can be a value greater than 90%. The preset similarity threshold can be set according to the actual situation, and this application embodiment does not impose any limitations on it.

[0067] In this embodiment, by calculating the similarity between the distribution of carrier frequency within the target carrier period and the sinusoidal distribution, and determining whether to update the preset quantity based on the similarity, the noise reduction effect can be further improved.

[0068] For example, when updating the currently used preset quantity, a new preset quantity can be determined from even numbers greater than 4, excluding the currently used preset quantity. For instance, if the currently used preset quantity is 8, meaning the target carrier period can be 8 times the motor current control period, a new preset quantity can be determined based on similarity. If the difference between the similarity and the preset similarity threshold is large, a new preset quantity with a large difference from the currently used preset quantity can be selected. If the difference between the similarity and the preset similarity threshold is small, a new preset quantity with a small difference from the currently used preset quantity can be selected.

[0069] In this embodiment, by determining a new preset number to modulate the distribution of the PWM carrier within the target carrier period, a PWM carrier that is closer to a sinusoidal distribution is obtained, thereby improving the noise cancellation effect and achieving white noise.

[0070] For example, the preset sinusoidal distribution described in the above embodiment can be the distribution of a carrier centered at a preset frequency within the target carrier period, where the preset frequency is half of the sum of the maximum and minimum carrier frequencies allowed by the motor for pulse width modulation.

[0071] In this embodiment, the carrier frequency distribution within the target carrier period is half the sum of the maximum and minimum carrier frequencies of the PWM carrier, which can maximize noise elimination.

[0072] To facilitate understanding of the pulse width modulation carrier modulation method provided in the embodiments of this application, the technical solutions provided in the embodiments of this application will be described in detail below.

[0073] Assume that, in addition to satisfying the above formula (1), the target carrier period can also satisfy the following formula (2):

[0074] T p =8KT d K = 1, 2, ..., n (2)

[0075] In formula (2), Tp is the target carrier period and Td is the motor current control period.

[0076] Based on the above settings, we can obtain... Figure 3 The PWM carrier distribution shown is as follows: Figure 3 This is a schematic diagram illustrating the distribution of a PWM carrier within a target carrier period, provided as an embodiment of this application. According to... Figure 3 As shown, a target carrier cycle includes 8 motor current control cycles, and the envelope of the PWM carrier obtained in a target carrier cycle is sinusoidal, with the center point of the sinusoidal distribution being half of the sum of the maximum and minimum values ​​of the PWM carrier frequency.

[0077] In summary, the technical solution provided by the embodiments of this application can obtain a sinusoidal PWM carrier distribution within the target carrier period, thereby eliminating noise caused by resonance.

[0078] Figure 4 A schematic diagram of a modulation device 40 for a pulse width modulation carrier provided in this application embodiment is shown below. For example, please refer to [link to example diagram]. Figure 4 As shown, the modulation device 40 for the pulse width modulation carrier may include:

[0079] The acquisition module 401 is used to acquire the resonant frequency of the frequency converter. The resonant frequency is the frequency corresponding to the resonant point when the frequency converter generates resonance during operation.

[0080] Processing module 402 is used to determine the target carrier period based on the resonant frequency;

[0081] Output module 403 is used to control the output of motor current within the target carrier period so that the pulse width modulation carrier obtained within the target carrier period is a sine wave.

[0082] Optionally, processing module 402 is specifically used to process according to the formula Determine the target carrier period; where Tp is the target carrier period and fn is the resonant frequency.

[0083] Optionally, the target carrier period is a preset number of times the control period of the motor current, and the preset number is an even number greater than 4.

[0084] Optionally, the device further includes an update module 404, which is used to obtain the carrier frequency of the pulse width modulation carrier corresponding to the motor current based on the motor current output in the target carrier period; calculate the similarity between the distribution of the carrier frequency in the target carrier period and a preset sine distribution; when the similarity is less than a preset similarity threshold, update the currently used preset quantity, and output the motor current in the new target carrier period corresponding to the new preset quantity.

[0085] Optionally, update module 404 is used to determine the value other than the currently used preset quantity as the new preset quantity for even numbers greater than 4.

[0086] Optionally, the preset sinusoidal distribution is the distribution of the carrier centered at a preset frequency within the target carrier period, and the preset frequency is half of the sum of the maximum and minimum carrier frequencies allowed by the motor for pulse width modulation.

[0087] The modulation apparatus for pulse width modulation carrier provided in this application embodiment can execute the technical solution of the modulation method for pulse width modulation carrier in any of the above embodiments. Its implementation principle and beneficial effects are similar to those of the modulation method for pulse width modulation carrier. Please refer to the implementation principle and beneficial effects of the modulation method for pulse width modulation carrier, which will not be repeated here.

[0088] Figure 5 This is a schematic diagram of an electronic device structure provided in this application. Figure 5 As shown, the electronic device 500 may include at least one processor 501 and a memory 502.

[0089] The memory 502 is used to store programs. Specifically, the program may include program code, which includes computer operation instructions.

[0090] The memory 502 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0091] Processor 501 executes computer execution instructions stored in memory 502 to implement the pulse width modulation carrier modulation method described in the foregoing method embodiments. Processor 501 may be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. Specifically, when implementing the pulse width modulation carrier modulation method described in the foregoing method embodiments, the electronic device may be, for example, a terminal, a server, or other electronic device with processing capabilities. When implementing the pulse width modulation carrier modulation method described in the foregoing method embodiments, the electronic device may be a frequency converter.

[0092] Optionally, the electronic device 500 may also include a communication interface 503. In specific implementations, if the communication interface 503, memory 502, and processor 501 are implemented independently, they can be interconnected via a bus to complete communication. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc., but this does not imply that there is only one bus or one type of bus.

[0093] Optionally, in a specific implementation, if the communication interface 503, memory 502, and processor 501 are integrated on a single chip, then the communication interface 503, memory 502, and processor 501 can communicate through an internal interface.

[0094] This application also provides a computer-readable storage medium, which may include various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. Specifically, the computer-readable storage medium stores program instructions, which are used in the methods described in the above embodiments.

[0095] This application also provides a program product including executable instructions stored in a readable storage medium. At least one processor of an electronic device can read the executable instructions from the readable storage medium, and the processor executes the executable instructions to cause the electronic device to implement the pulse width modulation carrier modulation method provided in the various embodiments described above.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A modulation method for a pulse width modulation carrier, characterized in that, include: The resonant frequency of the frequency converter is obtained, which is the frequency corresponding to the resonance point when the frequency converter generates resonance during operation. According to the formula The target carrier period is determined; where Tp is the target carrier period and fn is the resonant frequency. The motor current is controlled to be output within the target carrier period so that the pulse width modulation carrier obtained within the target carrier period is a sine wave. The method further includes: Based on the motor current output within the target carrier period, the carrier frequency of the pulse width modulation carrier corresponding to the motor current is obtained; Calculate the similarity between the distribution of the carrier frequency within the target carrier period and the preset sinusoidal distribution; wherein, the preset sinusoidal distribution is the distribution of the carrier centered at a preset frequency within the target carrier period, and the preset frequency is half of the sum of the maximum and minimum carrier frequencies of the pulse width modulation carrier allowed by the motor; If the similarity is less than a preset similarity threshold, the currently used preset quantity is updated, and the motor current is output in the new target carrier period corresponding to the new preset quantity.

2. The method according to claim 1, characterized in that, The target carrier period is a preset number of times the control period of the motor current, and the preset number is an even number greater than 4.

3. The method according to claim 1, characterized in that, The update of the currently used preset quantity includes: For even numbers greater than 4, the values ​​other than the currently used preset quantity will be determined as the new preset quantity.

4. The method according to claim 1, characterized in that, The preset sinusoidal distribution is the distribution of a carrier wave centered at a preset frequency within the target carrier period. The preset frequency is half the sum of the maximum and minimum carrier frequencies allowed by the motor for pulse width modulation.

5. A modulation device for a pulse width modulation carrier wave, characterized in that, include: The acquisition module is used to acquire the resonant frequency of the frequency converter, which is the frequency corresponding to the resonance point when the frequency converter generates resonance during operation. Processing module, used to process formulas The target carrier period is determined; where Tp is the target carrier period and fn is the resonant frequency. The output module is used to control the output of motor current during the target carrier period so that the pulse width modulation carrier obtained during the target carrier period is a sine wave. The update module is used to obtain the carrier frequency of the pulse width modulation carrier corresponding to the motor current based on the motor current output within the target carrier period; calculate the similarity between the distribution of the carrier frequency within the target carrier period and a preset sinusoidal distribution; wherein the preset sinusoidal distribution is the distribution of the carrier centered at a preset frequency within the target carrier period, and the preset frequency is half of the sum of the maximum and minimum carrier frequencies allowed for the motor's pulse width modulation carrier; if the similarity is less than a preset similarity threshold, the currently used preset quantity is updated, and the motor current is output within the new target carrier period corresponding to the new preset quantity.

6. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-4.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1-4.

Images