CN110108937B - Wireless charging frequency selection method and system based on harmonic analysis - Google Patents
Wireless charging frequency selection method and system based on harmonic analysis Download PDFInfo
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R23/16—Spectrum analysis; Fourier analysis
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- G—PHYSICS
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- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0807—Measuring electromagnetic field characteristics characterised by the application
- G01R29/0814—Field measurements related to measuring influence on or from apparatus, components or humans, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0864—Measuring electromagnetic field characteristics characterised by constructional or functional features
- G01R29/0871—Complete apparatus or systems; circuits, e.g. receivers or amplifiers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0864—Measuring electromagnetic field characteristics characterised by constructional or functional features
- G01R29/0892—Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value
Abstract
The invention discloses a wireless charging frequency selection method and a wireless charging frequency selection system based on harmonic analysis, wherein the method comprises the following steps: establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point, and calculating to obtain the current value of each subharmonic primary coil and each subharmonic secondary coil flowing through the primary coil and the secondary coil according to the numerical model; obtaining the maximum harmonic current value of the primary and secondary coils in the overlapped working frequency section and the corresponding harmonic frequency; establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity at the wireless charging equipment according to the electromagnetic simulation model; and calculating a margin according to the electric field intensity, judging whether the normal work of the wireless charging equipment is influenced under the coexistence interference scene and the initial working frequency point according to the margin, and if the normal work is not influenced, taking the initial working frequency point as a wireless charging frequency selection value.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a wireless charging frequency selection method and system based on harmonic analysis.
Background
As a novel charging technology, a Wireless Power Transmission (WPT) technology has the characteristics of simple and convenient charging process, simplified charging facilities, good interaction with a network, and the like, and in recent years, the Wireless charging industry in china has been rapidly developed. However, china does not aim at frequency division of electric vehicles, and currently, selection of working frequency points and frequency bands only refers to the international IEC/ISO/SAE relevant standards directly, and theory and practice basis support based on deep research of a system is lacked. In practical applications based on this, the problem of coexistence interference of the wireless charging device to other systems using the same frequency or adjacent frequencies cannot be solved well, so that the wireless charging frequency selection of the wireless charging device, especially the vehicle-mounted wireless charging device, needs to be solved urgently.
Disclosure of Invention
In order to solve the problem of coexistence interference of wireless charging equipment to other systems using the same frequency or adjacent frequencies in the background art, the invention provides a method and a system for selecting wireless charging frequency based on harmonic analysis, wherein the method and the system determine a frequency range which is not influenced by interference of peripheral adjacent frequency equipment by analyzing the harmonic of the wireless charging equipment and analyzing the coexistence interference with the peripheral adjacent frequency equipment; the wireless charging frequency selection method based on harmonic analysis comprises the following steps:
determining one or more adjacent frequency devices in a coexistence interference scene where a wireless charging device is located, and obtaining working frequency segments of the one or more adjacent frequency devices;
selecting an initial working frequency point in a preset wireless charging candidate frequency band according to a preset rule;
obtaining equipment parameters of a wireless charging equipment high-frequency inverter to be subjected to frequency selection;
establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point, and calculating to obtain the current value of each subharmonic primary coil and each subharmonic frequency flowing through the primary coil and the secondary coil according to the numerical model;
comparing the harmonic frequencies with the working frequency sections of the one or more adjacent frequency devices to obtain superposed working frequency sections; selecting the maximum harmonic current value of the primary coil and the secondary coil and the corresponding harmonic frequency in the overlapped working frequency section;
establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity at the wireless charging equipment according to the electromagnetic simulation model;
and calculating a margin according to the electric field intensity, judging whether the normal work of the wireless charging equipment is influenced under the initial working frequency point under the coexistence interference scene according to the margin and a preset rule, and taking the initial working frequency point as a wireless charging frequency selection value if the normal work is not influenced.
Further, if it is determined that the normal operation of the wireless charging device is affected under the coexisting interference scenario and the initial operating frequency point, reselecting the initial operating frequency point, and calculating a margin corresponding to a new initial operating frequency point for determination, until the determination result corresponding to the selected initial operating frequency point does not affect the normal operation of the wireless charging device, and taking the initial operating frequency point as a wireless charging frequency selection value.
Further, a plurality of working frequency points are selected in a preset wireless charging candidate frequency band according to a preset interval;
calculating the corresponding margin of each working frequency point, and judging whether each working frequency point can influence the normal work of the wireless charging equipment;
and obtaining a plurality of working frequency points which do not influence the normal work of the wireless charging equipment to form a wireless charging frequency selection frequency band.
Further, establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point comprises the following steps:
decomposing a square wave voltage output by a high-frequency inverter of the wireless charging equipment into an algebraic sum of a fundamental wave with an initial working frequency as a basic frequency and a plurality of higher harmonics according to a Fourier transform method;
and respectively equating the primary and secondary coils to be series branches of a current controlled voltage source and an inductor by a controlled element equivalence method, and establishing an electromagnetic interference numerical model according to the equivalent primary and secondary coils.
Further, the electromagnetic interference numerical model is
Wherein the content of the first and second substances,
U pk an input voltage for the resonant compensation network; l is P 、L S Self-inductance of the primary coil and the secondary coil respectively; c P 、C S Resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r P 、R S Internal resistances of the primary side and secondary side coils, respectively; r e A load resistance; k omega s Is the k harmonic angular frequency;
the current value of each subharmonic primary and secondary coil flowing through the primary and secondary coils calculated and obtained according to the numerical model is as follows:
further, comparing the harmonic frequencies with the working frequency bands of the one or more adjacent frequency devices to obtain a coincident working frequency band, includes:
performing union processing on the working frequency segments of one or more adjacent frequency devices to obtain union working frequency segments of the frequency devices;
and taking intersection of the union working frequency section and the lyric harmonic frequency to obtain a superposed working frequency section.
Further, establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency, wherein the electromagnetic simulation model comprises the following steps:
establishing a coexisting interference electromagnetic simulation model in electromagnetic simulation software ANSYS according to the coexisting interference scene, and obtaining the electric field intensity of the wireless charging equipment through simulation.
Further, calculating a margin according to the electric field strength, and determining whether normal operation of the wireless charging device is affected under the coexistence interference scene and the initial operating frequency point according to the margin and a preset rule, including:
calculating a signal-to-noise ratio according to the electric field intensity at the wireless charging device, wherein the signal-to-noise ratio calculation formula is as follows:
SNR＝E/A sen (dB)
wherein A is sen The minimum sensitivity value of the coexisting interference equipment is preset;
calculating a margin according to the signal-to-noise ratio, the margin A mg The calculation formula of (2) is as follows:
A mg ＝A rel +A damp -SNR
wherein A is rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
The wireless charging frequency selection system based on harmonic analysis comprises:
the wireless charging device comprises an adjacent frequency device input unit, a wireless charging device and a wireless charging device, wherein the adjacent frequency device input unit is used for determining one or more adjacent frequency devices in a coexistence interference scene where the wireless charging device is located and obtaining working frequency sections of the one or more adjacent frequency devices;
the wireless charging device comprises an initial setting unit, a first setting unit and a second setting unit, wherein the initial setting unit is used for determining one or more adjacent frequency devices in a coexistence interference scene where the wireless charging device is located and obtaining working frequency bands of the one or more adjacent frequency devices;
the initial setting unit is used for obtaining equipment parameters of a wireless charging equipment high-frequency inverter to be subjected to frequency selection;
the electromagnetic interference calculation unit is used for establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point, and calculating and obtaining the current value of each subharmonic primary coil and each subharmonic frequency flowing through the primary coil and the secondary coil according to the numerical model;
the electromagnetic interference calculation unit is used for comparing the harmonic frequencies with the working frequency sections of the one or more adjacent frequency devices to obtain superposed working frequency sections; selecting the maximum harmonic current value of the primary coil and the secondary coil and the corresponding harmonic frequency in the overlapped working frequency section;
the electromagnetic simulation unit is used for establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity of the wireless charging equipment according to the electromagnetic simulation model;
and the judging unit is used for calculating a margin according to the electric field intensity, judging whether the normal work of the wireless charging equipment is influenced under the initial working frequency point in the coexistence interference scene according to the margin and a preset rule, and taking the initial working frequency point as a wireless charging frequency selection value if the normal work is not influenced.
Further, if the determining unit determines that the normal operation of the wireless charging device is affected under the coexistence interference scenario and the initial operating frequency point, the initial setting unit reselects the initial operating frequency point, and performs determination by recalculating the margin corresponding to the new initial operating frequency point by the determining unit until the determination result corresponding to the selected initial operating frequency point does not affect the normal operation of the wireless charging device, and uses the initial operating frequency point as the wireless charging frequency selection value.
Further, the initial setting unit is configured to select a plurality of operating frequency points in a preset wireless charging candidate frequency band at preset intervals;
the judgment unit calculates the corresponding margin of each working frequency point and judges whether each working frequency point can influence the normal work of the wireless charging equipment;
the judging unit obtains a plurality of working frequency points which do not influence the normal work of the wireless charging equipment to form a wireless charging frequency selection frequency band.
Further, the electromagnetic interference calculating unit is configured to decompose the square wave voltage output by the high-frequency inverter of the wireless charging device into an algebraic sum of a fundamental wave and a plurality of higher harmonics, where an initial operating frequency is a fundamental frequency, according to a fourier transform method;
and the electromagnetic interference calculation unit is used for respectively equating the primary and secondary coils to be series branches of a current controlled voltage source and an inductor by a controlled element equivalence method, and establishing an electromagnetic interference numerical model according to the equivalent primary and secondary coils.
Further, the electromagnetic interference numerical model of the electromagnetic interference calculation unit is
Wherein, the first and the second end of the pipe are connected with each other,
U pk an input voltage for the resonant compensation network; l is a radical of an alcohol P 、L S Self-inductance of the primary coil and the secondary coil respectively; c P 、C S Resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r P 、R S Primary side and secondary side respectivelyThe internal resistance of the side coil; r e A load resistance; k omega s Is the k harmonic angular frequency;
the current value of each subharmonic primary and secondary coil flowing through the primary and secondary coils calculated and obtained according to the numerical model is as follows:
further, the electromagnetic interference calculation unit is configured to perform union processing on the operating frequency segments of one or more adjacent frequency devices to obtain a union operating frequency segment of the frequency device; and the intersection of the union working frequency segment and the lyric harmonic frequency is taken to obtain a superposed working frequency segment.
Further, the electromagnetic simulation unit is configured to establish a coexistence interference electromagnetic simulation model in electromagnetic simulation software ANSYS according to the coexistence interference scene, and obtain the electric field intensity at the wireless charging device through simulation.
Further, the judging unit is configured to calculate a signal-to-noise ratio according to the electric field intensity at the wireless charging device, where the signal-to-noise ratio calculation formula is:
SNR＝E/A sen (dB)
wherein A is sen Setting a preset minimum sensitivity value of coexisting interference equipment;
the judgment unit calculates a margin A according to the signal-to-noise ratio mg The calculation formula of (c) is:
A mg ＝A rel +A damp -SNR
wherein A is rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
The invention has the beneficial effects that: the technical scheme of the invention provides a wireless charging frequency selection method and a wireless charging frequency selection system based on harmonic analysis, wherein the method and the system start from the overlapping characteristic of frequency spectrums of wireless charging equipment and adjacent frequency equipment, and cover the judgment and analysis of the coexistence passability of a wireless power transmission system from frequency selection to the establishment of a numerical model and an electromagnetic simulation model and then to the last; the electromagnetic interference problem under the actual coexistence interference scene is fully considered, support is provided for selection of working frequency points and frequency bands of the current wireless charging equipment, particularly the wireless charging system of the electric automobile, and a foundation is laid for realizing comprehensive optimization of the technical performance, the economic performance and the safety of the wireless charging system.
Drawings
Exemplary embodiments of the invention may be more completely understood in consideration of the following drawings:
fig. 1 is a flowchart of a method for selecting a wireless charging frequency based on harmonic analysis according to an embodiment of the present invention;
fig. 2 is a structural diagram of a wireless charging frequency selection system based on harmonic analysis according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a method for selecting a wireless charging frequency based on harmonic analysis according to an embodiment of the present invention; as shown in fig. 1, the method includes:
in this embodiment, the wireless charging device includes multiple devices that implement wireless charging through a wireless charging technology (WPT). For clarity, the wireless charging system mounted on the electric vehicle is taken as an example for description.
For the vehicle-mounted wireless charging system of the electric vehicle, the coexisting interference scene may be a parking lot, and the adjacent frequency device may be an adjacent vehicle-mounted wireless charging system of the electric vehicle or other adjacent frequency devices (generally, radio communication service frequency spectrums from 9KHz to 30 MHz) near the parking lot, and the coexisting interference scene may be determined according to the actually simulated coexisting interference scene.
the selecting of the operating frequency point may preferentially select a frequency point near the middle of the candidate frequency band as the initial operating frequency point.
The wireless charging candidate frequency band is comprehensively determined by researching and analyzing the current domestic and foreign frequency band division condition and the working frequency of the wireless charging system of the electric vehicle suggested by automobile enterprises, equipment suppliers and scientific research institutions, and considering factors such as component model selection, domestic and foreign docking, policy standards and the like.
further, according to a Fourier transform method, the square wave voltage output by a high-frequency inverter of the wireless charging equipment is decomposed into an algebraic sum of a fundamental wave with an initial working frequency as a basic frequency and a plurality of higher harmonics;
the specific square wave voltage of the high frequency inverter can be expressed as follows:
wherein, ω s =2 π/Ts, ω s is the resonance angular frequency, and is obtained according to the initial working frequency point; from the above formula, the input voltage of the resonance compensation network is composed of the fundamental wave and the odd harmonics, and the harmonic voltage amplitude decreases with the increase of the harmonic number.
The resonance is compensated through a resonance compensation topology, which includes four kinds of topologies, namely SS, SP, PP and PS.
And respectively equating the primary and secondary coils to be series branches of a current controlled voltage source and an inductor by a controlled element equivalence method, and establishing an electromagnetic interference numerical model according to the equivalent primary and secondary coils.
Further, the electromagnetic interference numerical model is
Wherein the content of the first and second substances,
U pk an input voltage for the resonant compensation network; l is a radical of an alcohol P 、L S Self-inductance of the primary coil and the secondary coil respectively; c P 、C S Resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r P 、R S Internal resistances of the primary side and secondary side coils, respectively; r e A load resistance; k omega s Is the k harmonic angular frequency;
the current value of each subharmonic primary and secondary coil flowing through the primary and secondary coils calculated and obtained according to the numerical model is as follows:
for certain wireless power transfer systems, L thereof P 、L S 、C P 、C S 、R P 、R S 、R e And M is a fixed value, so the sum of the current harmonic times and the voltage harmonic times in the magnetic coupling mechanism is basically consistent, namely, the current flowing through the primary coil and the secondary coil consists of fundamental current and odd harmonic current. Through calculation, the current value of each subharmonic flowing through the primary coil and the secondary coil can be obtained through solving.
further, the obtaining of the overlapped operating frequency segment may be performing union processing on the operating frequency segments of one or more adjacent frequency devices to obtain a union operating frequency segment of the frequency device; and taking the intersection of the union working frequency section and the lyric harmonic frequency to obtain a superposed working frequency section.
in the embodiment, the electromagnetic simulation model is established in electromagnetic simulation software ANSYS according to a coexistence interference scene, and in the embodiment, the coexistence interference scene can be determined according to the minimum parking belt, parking space and lane width of various vehicle type architectural designs in JGJ100-1998 garage architectural design Specification; according to SAE standard, WPT3 (11.1 kW) circular coil magnetic coupling mechanism with highest power grade is selected. Through simulation, the electric field strength at the wireless charging device is obtained.
Further, a signal-to-noise ratio is calculated according to the electric field intensity at the wireless charging device, and the signal-to-noise ratio calculation formula is as follows:
SNR＝E/A sen (dB)
wherein A is sen Setting a preset minimum sensitivity value of coexisting interference equipment;
calculating a margin according to the signal-to-noise ratio, the margin A mg The calculation formula of (2) is as follows:
A mg ＝A rel +A damp -SNR
wherein A is rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
Further, if it is determined that the normal operation of the wireless charging device is affected under the coexisting interference scenario and the initial operating frequency point, reselecting the initial operating frequency point, and calculating a margin corresponding to a new initial operating frequency point for determination, until the determination result corresponding to the selected initial operating frequency point does not affect the normal operation of the wireless charging device, and taking the initial operating frequency point as a wireless charging frequency selection value.
Further, a plurality of working frequency points are selected in a preset wireless charging candidate frequency band according to a preset interval;
calculating the corresponding margin of each working frequency point, and judging whether each working frequency point can influence the normal work of the wireless charging equipment;
and obtaining a wireless charging frequency selection frequency band formed by a plurality of working frequency points which do not influence the normal work of the wireless charging equipment.
Fig. 2 is a structural diagram of a wireless charging frequency selection system based on harmonic analysis according to an embodiment of the present invention. As shown in fig. 2, the system includes:
an adjacent-frequency device input unit 210, where the adjacent-frequency device input unit 210 is configured to determine one or more adjacent-frequency devices in a coexistence interference scenario where a wireless charging device is located, and obtain a working frequency segment of the one or more adjacent-frequency devices;
an initial setting unit 220, where the initial setting unit 220 is configured to determine one or more adjacent channel devices in a coexistence interference scenario where a wireless charging device is located, and obtain a working frequency segment of the one or more adjacent channel devices;
the initial setting unit 220 is configured to obtain device parameters of a wireless charging device high-frequency inverter to be subjected to frequency selection;
an electromagnetic interference calculating unit 230, where the electromagnetic interference calculating unit 230 is configured to establish an electromagnetic interference numerical model of the primary and secondary coils of the high-frequency inverter according to the device parameters at an initial working frequency point, and calculate and obtain a current value of each sub-harmonic primary and secondary coil flowing through the primary and secondary coils and each sub-harmonic frequency according to the numerical model;
the electromagnetic interference calculating unit 230 is configured to compare the harmonic frequencies with the working frequency bands of the one or more adjacent frequency devices to obtain a superposed working frequency band; selecting the maximum harmonic current value of the primary and secondary coils and the corresponding harmonic frequency from the superposed working frequency section;
further, the electromagnetic interference calculating unit 230 is configured to decompose the square wave voltage output by the high-frequency inverter of the wireless charging device into an algebraic sum of a fundamental wave and a plurality of higher harmonics, where an initial operating frequency is a fundamental frequency, according to a fourier transform method;
the electromagnetic interference calculation unit 230 is configured to respectively equate the primary and secondary coils to a series branch of a current-controlled voltage source and an inductor by a controlled element equivalence method, and establish an electromagnetic interference numerical model according to the equated primary and secondary coils.
Further, the electromagnetic interference calculation unit 230 has an electromagnetic interference numerical model of
Wherein, the first and the second end of the pipe are connected with each other,
U pk an input voltage for the resonant compensation network; l is a radical of an alcohol P 、L S Self-inductance of the primary coil and the secondary coil respectively; c P 、C S Resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r P 、R S Internal resistances of the primary side and secondary side coils, respectively; r e A load resistance; k omega s Is the k harmonic angular frequency;
the current value of each sub-harmonic primary and secondary coil flowing through the primary and secondary coils calculated according to the numerical model is as follows:
further, the electromagnetic interference calculating unit 230 is configured to perform union processing on the working frequency segments of one or more adjacent frequency devices to obtain a union working frequency segment of the frequency device; and the intersection of the union working frequency band and the lyric harmonic frequency is obtained to obtain a superposed working frequency band.
The electromagnetic simulation unit 240 is configured to establish an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity at the wireless charging equipment according to the electromagnetic simulation model;
further, the electromagnetic simulation unit 240 is configured to establish a coexistence interference electromagnetic simulation model in electromagnetic simulation software ANSYS according to a coexistence interference scene, and obtain the electric field intensity at the wireless charging device through simulation.
A determining unit 250, where the determining unit 250 is configured to calculate a margin according to the electric field strength, determine whether the normal operation of the wireless charging device is affected under the coexistence interference scenario and the initial operating frequency point according to the margin and a preset rule, and if the normal operation is not affected, take the initial operating frequency point as a wireless charging frequency selection value.
Further, the determining unit 250 is configured to calculate a signal-to-noise ratio according to the electric field intensity at the wireless charging device, where the signal-to-noise ratio is calculated according to a formula:
SNR＝E/A sen (dB)
wherein A is sen Setting a preset minimum sensitivity value of coexisting interference equipment;
the determining unit 250 calculates a margin according to the signal-to-noise ratio, the margin A mg The calculation formula of (c) is:
A mg ＝A rel +A damp -SNR
wherein, A rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
Further, if the determining unit 250 determines that the normal operation of the wireless charging device is affected under the coexistence interference scenario and the initial operating frequency point, the initial setting unit 220 reselects the initial operating frequency point, and performs determination by recalculating, by the determining unit 250, a margin corresponding to a new initial operating frequency point until the determination result corresponding to the selected initial operating frequency point does not affect the normal operation of the wireless charging device, and uses the initial operating frequency point as a wireless charging frequency selection value.
Further, the initial setting unit 220 is configured to select a plurality of operating frequency points in a preset wireless charging candidate frequency band according to a preset interval;
the determining unit 250 calculates a margin corresponding to each operating frequency point, and determines whether each operating frequency point affects normal operation of the wireless charging device;
the determining unit 250 obtains a plurality of operating frequency points that do not affect the normal operation of the wireless charging device to form a wireless charging frequency selection frequency band.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore, may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Reference to step numbers in this specification is only for distinguishing between steps and is not intended to limit the temporal or logical relationship between steps, which includes all possible scenarios unless the context clearly dictates otherwise.
Moreover, those of skill in the art will appreciate that while some embodiments described herein include some features included in other embodiments, not others, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination.
Various component embodiments of the disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure may also be embodied as device or system programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present disclosure may be stored on a computer-readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website, or provided on a carrier signal, or provided in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The disclosure may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several systems, several of these systems may be embodied by one and the same item of hardware.
While the foregoing is directed to embodiments of the present disclosure, it is noted that various improvements, modifications, and changes may be made by those skilled in the art without departing from the spirit of the present disclosure, and it is intended that such improvements, modifications, and changes fall within the scope of the present disclosure.
Claims (16)
1. A wireless charging frequency selection method based on harmonic analysis comprises the following steps:
determining one or more adjacent frequency devices in a coexistence interference scene where a wireless charging device is located, and obtaining working frequency segments of the one or more adjacent frequency devices;
selecting an initial working frequency point in a preset wireless charging candidate frequency band according to a preset rule;
acquiring equipment parameters of a wireless charging equipment high-frequency inverter to be subjected to frequency selection;
establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point, and calculating to obtain current values of the primary coil and the secondary coil of each subharmonic wave flowing through the primary coil and the secondary coil and each subharmonic frequency according to the numerical model;
comparing the harmonic frequencies with the working frequency sections of the one or more adjacent frequency devices to obtain superposed working frequency sections; selecting the maximum harmonic current value of the primary coil and the secondary coil and the corresponding harmonic frequency in the overlapped working frequency section;
establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity at the wireless charging equipment according to the electromagnetic simulation model;
and calculating a margin according to the electric field intensity, judging whether the normal work of the wireless charging equipment is influenced under the initial working frequency point under the coexistence interference scene according to the margin and a preset rule, and taking the initial working frequency point as a wireless charging frequency selection value if the normal work is not influenced.
2. The method of claim 1, wherein: and if the situation that the normal work of the wireless charging equipment is influenced under the coexistence interference scene and the initial working frequency point is judged, reselecting the initial working frequency point, calculating a margin corresponding to a new initial working frequency point for judgment, and taking the initial working frequency point as a wireless charging frequency selection value until the judgment result corresponding to the selected initial working frequency point does not influence the normal work of the wireless charging equipment.
3. The method of claim 1, wherein:
selecting a plurality of working frequency points in a preset wireless charging candidate frequency band according to a preset interval;
calculating the corresponding margin of each working frequency point, and judging whether each working frequency point can influence the normal work of the wireless charging equipment;
and obtaining a plurality of working frequency points which do not influence the normal work of the wireless charging equipment to form a wireless charging frequency selection frequency band.
4. The method of claim 1, wherein establishing a numerical model of electromagnetic interference of the primary and secondary coils of the high-frequency inverter according to the device parameters at an initial operating frequency point comprises:
decomposing a square wave voltage output by a high-frequency inverter of the wireless charging equipment into an algebraic sum of a fundamental wave with an initial working frequency as a basic frequency and a plurality of higher harmonics according to a Fourier transform method;
and respectively equating the primary and secondary coils to be series branches of a current controlled voltage source and an inductor by a controlled element equivalence method, and establishing an electromagnetic interference numerical model according to the equivalent primary and secondary coils.
5. The method according to claim 1 or 4, characterized in that: the electromagnetic interference numerical model is as follows:
wherein, the first and the second end of the pipe are connected with each other,
C p 、C s resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r is p 、R s Internal resistances of the primary side and secondary side coils, respectively; r is e A load resistance; k omega s Is the k harmonic angular frequency;
and calculating and obtaining the current value of each subharmonic primary coil flowing through the primary coil and the secondary coil according to the numerical model
And the current value of each harmonic secondary coil
Comprises the following steps:
6. the method of claim 1, wherein comparing the respective harmonic frequencies to an operating frequency bin of the one or more adjacent frequency devices to obtain a coincident operating frequency bin comprises:
performing union processing on the working frequency segments of one or more adjacent frequency devices to obtain union working frequency segments of the adjacent frequency devices;
and taking intersection of the union set working frequency section and each subharmonic frequency to obtain a superposed working frequency section.
7. The method according to claim 1, wherein an electromagnetic simulation model under a coexisting interference scene is established according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; and calculating the electric field intensity at the wireless charging device according to the electromagnetic simulation model, including:
establishing a coexisting interference electromagnetic simulation model in electromagnetic simulation software ANSYS according to the coexisting interference scene, and obtaining the electric field intensity of the wireless charging equipment through simulation.
8. The method of claim 1, wherein calculating a margin according to the electric field strength, and determining whether normal operation of the wireless charging device is affected under the coexistence interference scenario and the initial operating frequency point according to the margin and a predetermined rule comprises:
calculating a signal-to-noise ratio according to the electric field intensity E at the wireless charging equipment, wherein the signal-to-noise ratio calculation formula is as follows:
SNR＝E/A sen the unit is dB;
wherein A is sen The minimum sensitivity value of the coexisting interference equipment is preset;
calculating a margin according to the signal-to-noise ratio, the margin A mg The calculation formula of (c) is:
A mg ＝A rel +A damp -SNR
wherein A is rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
9. A wireless charging frequency selection system based on harmonic analysis, the system comprising:
the wireless charging device comprises an adjacent frequency device input unit, a wireless charging device and a wireless charging device, wherein the adjacent frequency device input unit is used for determining one or more adjacent frequency devices in a coexistence interference scene where the wireless charging device is located and obtaining working frequency sections of the one or more adjacent frequency devices;
an initial setting unit for
Selecting an initial working frequency point in a preset wireless charging candidate frequency band according to a preset rule;
the initial setting unit is used for obtaining equipment parameters of a wireless charging equipment high-frequency inverter to be subjected to frequency selection;
the electromagnetic interference calculation unit is used for establishing an electromagnetic interference numerical model of the primary coil and the secondary coil of the high-frequency inverter according to the equipment parameters at an initial working frequency point, and calculating and obtaining the current value of each subharmonic primary coil and each subharmonic frequency flowing through the primary coil and the secondary coil according to the numerical model;
the electromagnetic interference calculation unit is used for comparing the harmonic frequencies with the working frequency sections of the one or more adjacent frequency devices to obtain superposed working frequency sections; selecting the maximum harmonic current value of the primary coil and the secondary coil and the corresponding harmonic frequency in the overlapped working frequency section;
the electromagnetic simulation unit is used for establishing an electromagnetic simulation model under a coexisting interference scene according to the maximum primary and secondary coil harmonic current value and the corresponding harmonic frequency; calculating the electric field intensity of the wireless charging equipment according to the electromagnetic simulation model;
and the judging unit is used for calculating a margin according to the electric field intensity, judging whether the normal work of the wireless charging equipment is influenced under the initial working frequency point in the coexistence interference scene according to the margin and a preset rule, and taking the initial working frequency point as a wireless charging frequency selection value if the normal work is not influenced.
10. The system of claim 9, wherein: if the judging unit judges that the normal work of the wireless charging equipment can be influenced under the coexistence interference scene and the initial working frequency point, the initial setting unit reselects the initial working frequency point, the judging unit recalculates the margin corresponding to the new initial working frequency point to judge until the judgment result corresponding to the selected initial working frequency point does not influence the normal work of the wireless charging equipment, and the initial working frequency point is used as the wireless charging frequency selection value.
11. The system of claim 9, wherein:
the initial setting unit is used for selecting a plurality of working frequency points in a preset wireless charging candidate frequency band according to a preset interval;
the judgment unit calculates the corresponding margin of each working frequency point and judges whether each working frequency point can influence the normal work of the wireless charging equipment;
the judging unit obtains a plurality of working frequency points which do not influence the normal work of the wireless charging equipment to form a wireless charging frequency selection frequency band.
12. The system of claim 9, wherein:
the electromagnetic interference calculation unit is used for decomposing the square wave voltage output by the high-frequency inverter of the wireless charging equipment into a fundamental wave with an initial working frequency as a basic frequency and an algebraic sum of a plurality of higher harmonics according to a Fourier transform method;
and the electromagnetic interference calculation unit is used for respectively equating the primary and secondary coils to be series branches of a current controlled voltage source and an inductor by a controlled element equivalence method, and establishing an electromagnetic interference numerical model according to the equivalent primary and secondary coils.
13. The system according to claim 9 or 12, characterized in that: the electromagnetic interference numerical model is as follows:
wherein, the first and the second end of the pipe are connected with each other,
C p 、C s resonance compensation capacitors of the primary coil and the secondary coil respectively; m is the mutual inductance of the magnetic coupling mechanism; r p 、R s Internal resistances of the primary side and secondary side coils, respectively; r e A load resistance; k omega s Is the k harmonic angular frequency;
and calculating to obtain the current value of each subharmonic primary coil flowing through the primary and secondary coils according to the numerical model
And the current value of each harmonic secondary coil
Comprises the following steps:
14. the system of claim 9, wherein: the electromagnetic interference calculation unit is used for performing union processing on the working frequency sections of one or more adjacent frequency devices to obtain union working frequency sections of the adjacent frequency devices; and taking intersection of the union set working frequency section and each subharmonic frequency to obtain a superposed working frequency section.
15. The system of claim 9, wherein: the electromagnetic simulation unit is used for establishing a coexisting interference electromagnetic simulation model in electromagnetic simulation software ANSYS according to a coexisting interference scene, and obtaining the electric field intensity of the wireless charging equipment through simulation.
16. The system of claim 9, wherein:
the judging unit is used for calculating a signal-to-noise ratio according to the electric field intensity of the wireless charging equipment, and the signal-to-noise ratio calculation formula is as follows:
SNR＝E/A sen the unit is dB;
wherein, A sen The minimum sensitivity value of the coexisting interference equipment is preset;
calculating a margin according to the signal-to-noise ratio, the margin A mg The calculation formula of (c) is:
A mg ＝A rel +A damp -SNR
wherein, A rel Protection ratio for pre-set co-existing interferers, A damp Attenuation value brought by a preset external shielding measure;
if the margin is greater than or equal to 0, judging that the normal work of the wireless charging equipment is not influenced;
and if the margin is less than 0, judging that the normal work of the wireless charging equipment is influenced.
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