CN111817451B

CN111817451B - Wireless charging system

Info

Publication number: CN111817451B
Application number: CN202010925647.0A
Authority: CN
Inventors: 王哲; 陆钧; 贺凡波; 葛俊杰; 马俊超
Original assignee: Beijing Invispower Co Ltd
Current assignee: Hefei Yougan Technology Co Ltd
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2021-02-02
Anticipated expiration: 2040-09-07
Also published as: CN111817451A

Abstract

The invention discloses a wireless charging system, which is divided into a transmitting end and a receiving end, wherein the transmitting end is provided with a transmitting end resonant network, the transmitting end resonant network at least comprises a transmitting coil and a first capacitor, the receiving end is provided with a receiving end resonant network, the receiving end resonant network at least comprises a receiving coil and a second capacitor, at least one of the transmitting end and the receiving end is provided with a correcting device, and the correcting device is one or two of a correcting inductor and a correcting capacitor; when the correcting device is a correcting inductor, the correcting device is connected with the transmitting coil in series or connected with the receiving coil in series; when the correction device is a correction capacitor, it is connected in parallel with the first capacitor or in parallel with the second capacitor. According to the wireless charging system, the total capacitance value or the total inductance value of the transmitting end resonant network and the receiving end resonant network is adjusted through the correcting device, so that the stability of resonance is ensured, the interference of an environmental electromagnetic field is reduced, and the maximum efficiency transmission and the minimum interference noise are obtained.

Description

Wireless charging system

Technical Field

The invention relates to the field of wireless charging, in particular to a wireless charging system.

Background

The wireless charging is a non-contact energy transmission mode, can realize the safe and efficient utilization of energy, particularly, the wireless charging adopted by the electric automobile capable of automatically driving and automatically parking can effectively support the whole unmanned operation of the automobile, and is an important direction for the development of new energy automobiles. The wireless transmission of electric energy is realized by exciting an alternating electromagnetic field, and the strength of the electromagnetic field is inevitably required to be improved for obtaining larger power transmission; on the other hand, wireless charging inevitably involves electromagnetic compatibility (EMC) problems due to the excitation of electromagnetic field energy in open space.

Patent CN110126648A "self-optimizing tuning control method for maximum current tracking in wireless charging of electric vehicle" proposes a method for obtaining maximum output current by adjusting the operating frequency of an inverter through frequency conversion control, wherein the frequency conversion adjustment can make both voltage and current contain abundant higher harmonics, and the frequent adjustment of the operating frequency causes the composition of harmonics to be very complex, and the electromagnetic noise energy of the harmonics can form electromagnetic interference through circuit connection or electromagnetic wave spatial coupling, which causes a large electromagnetic compatibility problem to the system itself and the surrounding environment.

Disclosure of Invention

The invention provides a wireless charging system which can reduce interference of an environmental electromagnetic field and obtain higher-efficiency transmission and low interference noise.

The wireless charging system is divided into a transmitting end and a receiving end, wherein the transmitting end is provided with an inverter and a transmitting end resonant network, the transmitting end resonant network at least comprises a transmitting coil and a first capacitor, the receiving end is provided with a rectifier and a receiving end resonant network, the receiving end resonant network at least comprises a receiving coil and a second capacitor, at least one end of the transmitting end and the receiving end is provided with a correcting device, and the correcting device is one or two of a correcting inductor and a correcting capacitor; when the correction device is a correction inductor, providing a variable inductance value to the terminal; when the correction device is a correction capacitor, a variable capacitance value is provided to the terminal.

Preferably, when the correction device is a correction inductor and is arranged at the transmitting end, the correction inductor is connected with the transmitting coil; when the correcting device is a correcting inductor and is arranged at the receiving end, the correcting inductor is connected with the receiving coil; when the correcting device is a correcting capacitor and is arranged at the transmitting end, the correcting capacitor is connected with the first capacitor; when the correction device is a correction capacitor and is arranged at the receiving end, the correction capacitor is connected with the second capacitor.

Preferably, when the correction device is a correction inductor and is disposed at the transmitting end, the correction inductor is connected in series with the transmitting coil; when the correcting device is a correcting inductor and is arranged at the receiving end, the correcting inductor is connected with the receiving coil in series; when the correcting device is a correcting capacitor and is arranged at the transmitting end, the correcting capacitor is connected with the first capacitor in parallel; when the correction device is a correction capacitor and is arranged at the receiving end, the correction capacitor is connected with the second capacitor in parallel.

Preferably, the transmitting end has the correction inductor and the correction capacitor, and the correction capacitor disposed at the transmitting end is: a transmitting end correction capacitor; the correction inductor arranged at the transmitting end is as follows: the transmitting end corrects the inductance; the receiving end is also provided with the correction inductor and the correction capacitor, and the correction capacitor arranged at the receiving end is as follows: the receiving end corrects the capacitance; the correction inductor arranged at the receiving end is as follows: the receiving end corrects the inductance; the transmitting end correction capacitor is connected with the first capacitor in parallel; the transmitting end correction inductor is connected with the transmitting coil in series; the receiving end correction capacitor is connected with the second capacitor in parallel; and the receiving end correction inductor is connected with the receiving coil in series.

Preferably, the receiving end correction capacitor provides a capacitance change value Δ C;

current I output by the inverter₁Comprises the following steps:

wherein, U_ABIs the output voltage of the inverter; u shape_abIs the input voltage of the rectifier; omega₀Is the resonant angular frequency of the system; m is the mutual inductance.

Preferably, when the capacitance change value Δ C is smaller than 0, the current output from the inverter generates a phase.

Preferably, the metal-oxide semiconductor field effect transistor switching tube of the inverter is: zero voltage switching and/or zero current switching.

Preferably, the operating frequency is in the gap between the lower and upper bands of the electromagnetic field in the environment.

Preferably, the operating frequency is 79-90 kHz.

Preferably, when the correction device is a correction inductor, the correction inductor has a control input port for controlling a change in inductance value; when the correction device is a correction capacitor, the electrolyte of the magnetorheological fluid is filled between the polar plates of the correction capacitor, and the coils are wound outside the polar plates.

According to the wireless charging system, the total capacitance value or the total inductance value of the transmitting end resonant network and the receiving end resonant network is adjusted through the correcting device, so that the stability of resonance is ensured, the interference of an environmental electromagnetic field is reduced, and the maximum efficiency transmission and the minimum interference noise are obtained.

Drawings

Fig. 1 is an overall topology diagram of the wireless charging system of the present invention.

Fig. 2 is a partial topology diagram of the wireless charging system of the present invention.

Fig. 3 is a schematic structural diagram of a transmitting coil and a receiving coil in the wireless charging system of the present invention.

Fig. 4 is a schematic diagram of the operating frequency range and the broadcast frequency band in the wireless charging system according to the present invention.

Fig. 5a to 5d are schematic diagrams of four structures of a transmitting end resonant network and a receiving end resonant network in the wireless charging system of the present invention.

Reference numerals:

a power supply 1; a DC converter 2; an inverter 3; a transmitting-end resonant network 4; a transmitting end controller 5; a transmitting end communication module 6; a receiving end resonant network 7; a rectifier 8; a filter 9; a load 10; a receiving-end controller 11; a receiving-end communication module 12; an upper case 13; a coil carrier 14; a coil 15; ferrite 16; a shield plate 17; a lower case 18; a transmitting terminal Tx; a receiving end Rx; a transmitting coil L1; a receiving coil L2; a filter inductance L0; the transmitting end corrects the inductance Lm 1; the receiving end corrects the inductance Lm 2; a first inductance C1; a second inductance C2; a transmitting end correction capacitor Cm 1; the receiving end corrects the capacitor Cm 2; a filter capacitor C0; controlling an input port IP; mosfet switch tubes S1, S2, S3 and S4; rectifier diodes D1, D2, D3, D4.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.

Referring to fig. 1 and 2, the wireless charging system of the present invention has a transmitting end Tx and a receiving end Rx. The transmitting terminal Tx rectifies and adjusts the power frequency ac power supplied from the power supply 1 through the dc converter 2, and then converts the rectified and adjusted power factor ac power into dc power. The direct current is then converted into high-frequency alternating current by the inverter 3. The high-frequency alternating current drives the transmitting coil L1 to work through the transmitting end resonant network 4. The transmitting-side resonant network 4 has a first capacitor C1 (compensation capacitor, which is not described separately in this application, and the first capacitor C1 functions as a compensation network) which forms a transmitting-side resonant loop with the transmitting coil L1 so as to generate an alternating magnetic field of a corresponding frequency to couple to the receiving coil L2 of the receiving terminal Rx, and the receiving coil L2 can induce an alternating current. The second capacitor C2 (compensation capacitor, and the second capacitor C2 functions as the compensation network) in the receiving-end resonant network 7 and the receiving coil L2 form a resonant loop.

The current received at the receiving terminal Rx is converted into dc by the rectifier 8, and then filtered by the filter 9 to supply power to the load 10, typically to charge a battery.

The transmitting end Tx is provided with a transmitting end controller 5, the receiving end Rx is provided with a receiving end controller 11, when the wireless charging work is carried out, the transmitting end controller 5 and the receiving end controller 11 collect parameters such as current and voltage of each part, the work of each part is controlled, and the transmitting end communication module 6 and the receiving end communication module 12 are interacted, so that the instruction and information transmission sharing of the double-side controller is realized.

In order to reduce the impact of the wireless charging system on the power grid and the problem of harmonic interference during operation, a rectifier bridge and a power factor correction circuit are provided in the dc converter 2 arranged at the transmitting end Tx. The transmitting terminal controller 5 controls the phase difference between the compensated current and voltage to make the input current sinusoidal, reduce the total harmonic factor of the input current, and improve the power factor.

The overall structure of the transmitting coil L1 and the receiving coil L2 is similar, and referring to fig. 3, the whole structure sequentially comprises: an upper case 13, a coil carrier 14, a coil 15, ferrites 16, a shield plate 17, and a lower case 18. The upper housing 13 and the lower housing 18 are located at the topmost and bottommost layers of the overall structure, primarily for enclosing the coil. The coil 15 is laid on ferrite 16, the ferrite 16 being typically a high permeability ferrite material. Between the ferrite 16 and the lower case 18, the shielding layer 17 is preferably a metal sheet made of aluminum alloy, and a ferromagnetic material and an aluminum alloy are generally used to reduce electromagnetic radiation interference of the wireless charging coil.

Through the arrangement, the noise intensity emitted outwards during wireless charging can be reduced, and the problem of electromagnetic compatibility is effectively overcome or improved. In order to further improve the electromagnetic compatibility of equipment and solve the problems of same frequency interference, adjacent frequency interference and the like of harmonic electromagnetic fields mainly faced by a wireless charging system, the working frequency f0 during wireless charging is fixed during charging, and the working frequency f0 and harmonics generated during working at the working frequency can avoid the frequency of the electromagnetic fields in the environment by selecting the working frequency f 0. The operating frequency f0 is preferably 79-90 kHz.

Taking car wireless charging as an example, electromagnetic fields in the environment may include railway communication systems (10 kHz-250 kHz), water radio (90 kHz-110 kHz), amateur radio (135.7-137.8 kHz) and medium wave broadcasting (526.5 kHz-1606.5 kHz), etc.

Wireless charging systems (e.g., electric car charging) are typically spaced apart from railway communication systems and marine radio systems by a distance that is greater than 5 meters away from each other, which does not present a risk of interference. The frequency band of wireless charging is not overlapped with amateur radio and medium wave broadcasting, but the distance between the wireless charging device and a medium wave broadcasting receiver (such as vehicle-mounted broadcasting device) is very small, harmonic waves generated during wireless charging operation can interfere with the medium wave broadcasting, and the medium wave broadcasting needs to be protected by taking electromagnetic compatibility measures.

According to the regulations of the national mandatory standard GB2017-80 'Medium wave broadcasting network coverage technology', the frequency range of the medium wave audio service broadcast in China is 526.5-1606.5kHz, the channel interval of the medium wave broadcast is 9kHz, the bandwidth of a transmitted signal is less than 10kHz, and the audio bandwidth is less than 4.5 kHz. There is a gap without carrier between the channel center of the carrier, i.e., the LSB (lower-side) and USB (upper-side) of the lower sideband of the channel, and this gap is 300 Hz.

And selecting one from the working frequency range of wireless charging as the working frequency, calculating the frequency of the nth harmonic wave, and judging the position of the nth harmonic wave in the broadcasting frequency band. Referring to fig. 4, a schematic diagram of the operating frequency range and broadcast frequency band is shown. The operating frequency of the preferred wireless charging system and its individual harmonics should fall outside the frequency range of the carrier channel, or within a gap in the center of the channel (as shown by the solid box in fig. 4), so as not to cause any interference with the medium audio reception. Secondly, the gap between adjacent channels of the carrier channel, i.e. the edge of the USB or LSB of the audio carrier (as shown by the dashed box in fig. 4), is more likely to generate interference than the gap that falls outside and in the center of the channel.

The following is an embodiment of wireless charging operation frequency selection, which takes the above midwave broadcasting in the overseas district as the example, wherein the transmission frequency of the midwave broadcasting is shown in table 1 below.

TABLE 1

The operating frequency of wireless charging is preset to be 85.5kHz, and the distribution of each harmonic is calculated as shown in table 2.

TABLE 2

When the wireless charging system of the present application uses 85.5kHz as the operating frequency, except for the 10 th and 14 th harmonics, each harmonic falls outside the frequency range of the medium-frequency channel, the 10 th harmonic thereof falls in the center of the 855kHz channel, and the 14 th harmonic thereof falls in the center of the 1197kHz channel. When other frequencies are used as the operating frequency, harmonics may fall into the LSB and USB regions, and therefore, the electromagnetic compatibility is better when 85.5kHz is selected as the operating frequency.

The following describes the transmitting-side resonant network 4 and the receiving-side resonant network 7 in the wireless charging system. For convenience of description, both may be referred to collectively as a resonant network. Referring to fig. 5a, 5b, 5c and 5d, four configurations of the resonant network are shown, namely "series-series resonance", "series-parallel resonance", "parallel-series resonance" and "parallel-parallel resonance", respectively. Of course, there are composite compensation structures such as LCC type and pi type.

In fig. 5a to 5d, R1 is the total resistance of the transmitting-side resonant tank, RL is the resistance of the load 10, and R2 is the total resistance of the receiving-side resonant tank. It should be noted that fig. 5a to 5d are for illustrating the structure that the two-side resonant network can use, and are used only for illustration and are not contradictory to the structure of fig. 2.

The relation between the resonance frequency and the inductance and the capacitance is as follows:

in the above formula, L is the total inductance value and C is the capacitance value. At the transmitting end Tx, the total inductance value is the overall inductance value including the transmitting coil L1; at the receiving end Rx, the total inductance value is the overall inductance value including the receiving coil L2. For the above-described resonant network consisting of ideal components, L may represent the coil inductance and C the compensation capacitance selected to match the selected operating frequency.

In the resonant network, the resonant frequency of a transmitting end resonant circuit formed by the transmitting coil L1 and the first capacitor C1 is f1, and the resonant frequency of a receiving end resonant circuit formed by the receiving coil L2 and the second capacitor C2 is f 2. If the driving frequency of the AC alternating input source of the transmitting-side resonant network is fk, when fk is equal to the aforementioned selected operating frequency f0, and is also equal to the resonant frequency of the transmitting-side resonant tank f1 and the resonant frequency of the receiving-side resonant tank f2, that is, f0= fk = f1= f2, the wireless charging system reaches a resonant state at the operating frequency f0, and the most efficient energy transmission can be realized.

However, since it is impossible to achieve complete accuracy in the manufacturing process, the capacitance of the compensation capacitor generally has a deviation of ± 0.5% to ± 20%, the winding process of the coil is more complicated, such as environmental changes of the metal body of the automobile and the like, the limitation of the installation conditions, and the deviation of the coil parameters caused by factors such as stray inductance and capacitance of the circuit is larger, and the deviation of the compensation capacitor and the inductance of the coil can cause the resonance frequency to deviate from the selected working frequency.

In order to overcome the above disadvantages, at least one of a correction inductor and a correction capacitor, which is a correction device, is added to the resonant network on at least one side of the transmitting terminal Tx or the receiving terminal Rx. For convenience of explanation, the correction inductance and the correction capacitance at the transmitting terminal Tx will be referred to as a transmitting terminal correction inductance Lm1 and a transmitting terminal correction capacitance Cm 1; the correction inductor and the correction capacitor at the receiving terminal Rx are referred to as a receiving terminal correction inductor Lm2 and a receiving terminal correction capacitor Cm 2. The correction inductor is also referred to as a transmitting-side correction inductor Lm1 when it is mounted on the transmitting side Tx, and referred to as a receiving-side correction inductor Lm2 when it is mounted on the receiving side Rx. The same applies to the correction of capacitance.

Any one side of the transmitting terminal Tx and the receiving terminal Rx is provided with a correction device, or both sides are provided with correction devices, which can be used in the present application. Meanwhile, the correction device can adopt a correction inductor or a correction capacitor, and the correction inductor and the correction capacitor can also be used simultaneously.

As shown in fig. 2, the correction devices are disposed on both sides, the transmitting terminal Tx has a transmitting terminal correction inductor Lm1 and a transmitting terminal correction capacitor Cm1, and the receiving terminal Rx further has a receiving terminal correction inductor Lm2 and a receiving terminal correction capacitor Cm 2.

The transmitting end correction inductor Lm1 and the receiving end correction inductor Lm2 may have the same structure and form, and for convenience of description, they will be collectively referred to as correction inductors. Similarly, the transmitting-side correction capacitor Cm1 and the receiving-side correction capacitor Cm2 will be collectively referred to as correction capacitors.

The correction inductor preferably adopts a saturated inductor winding and is provided with a control input port IP, the size of the inductance change value provided by the correction inductor is controlled by the size of the flowing direct current, when the current of the saturated inductor winding flowing through the correction inductor is small, the inductor is not saturated, the inductance change value is large, and when the flowing current is large, the inductor is saturated, and the inductance change value is small.

The correction capacitor preferably adopts a magnetorheological fluid capacitor, the magnetorheological fluid is used as electrolyte in the capacitor and is filled in the capacitor, a coil is wound outside the capacitor, and when current is introduced into the coil, a magnetic field is generated inside the capacitor. The magnetorheological fluid is formed by mixing micro soft magnetic particles with high magnetic conductivity and low magnetic hysteresis and non-magnetic conductive liquid, and the dielectric constant of the magnetorheological fluid is changed under the action of an external magnetic field. When the input current is increased, the magnetic field intensity in the coil is increased, the capacitance change value of the correction capacitor is increased, and when the input current is decreased, the magnetic field intensity in the coil is decreased, and the capacitance change value is decreased.

When the wireless charging system is in the resonant state, in the transmitting-side resonant network 4, the total inductance value is the total value of the inductance value of the transmitting coil L1 and the inductance variation value of the correction inductor, and the total value of the capacitance value of the first capacitor C1 and the capacitance variation value of the correction capacitor is the total capacitance value. The receiving end resonant network 7 works the same.

After the wireless charging system is produced or installed, the data on both sides of the transmitting end Tx and the receiving end Rx are respectively detected, if deviation exceeds an allowable range, a correcting device (correcting inductor or correcting capacitor) can be adjusted, so that the total inductance value and the total capacitance value are in a reasonable range, the wireless charging system can still reach a resonance state during wireless charging, and the system can be ensured to be fixed at a selected working frequency to work.

Referring now to fig. 2, the transmitter Tx does not show a dc converter, and the leftmost side is the inverter 3, and S1, S2, S3 and S4 are Mosfet (Metal-Oxide-Semiconductor Field-Effect Transistor) switching transistors of the inverter. D1, D2, D3 and D4 are the rectifier diodes of the rectifier 8. The filter 9 comprises a filter capacitor C0 and a filter inductor L0.

Since the wireless charging system operates at a high frequency, the conversion rate of voltage and current is high during the switching process of the switching devices such as the dc converter 2 and the inverter 3, which may cause additional loss and noise affecting the electromagnetic compatibility. In order to reduce the loss of the switching device, the current or voltage of the switching tube is zero in the turn-off and turn-on processes, so that a Zero Voltage Switch (ZVS) and a Zero Current Switch (ZCS) are used, the switching device can be in a zero voltage state when being turned on and in a zero current state when being turned off, and the switching loss and the electromagnetic interference of the switching device are theoretically zero because the switching device is switched at the current zero crossing point.

For the turn-off process of the switching tube, before the turn-off, the equivalent junction capacitors at the two ends of the switching tube are charged, and the switching tube is turned off when the current is just reduced to 0. For the conduction process, the equivalent junction capacitors at the two ends of the switching tube are used for discharging, so that the voltage of the junction capacitors is reduced to 0, the current is slowly increased to an output steady-state value, and the switching tube is switched on at the moment.

The correction device is capable of providing correction values, i.e. the inductance variation value and the capacitance variation value as described above, which enables the inductance value or the capacitance value in the original resonant network to be adjusted to meet the operating conditions of the soft switch.

In the wireless charging of the electric vehicle, a Mosfet switch tube (hereinafter referred to as a switch tube) is commonly used in the design of the inverter 3, and it is more favorable to switch on the Mosfet switch tube by using a zero-voltage switch. As shown in fig. 2, the capacitance value of the receiving-end correction capacitor Cm2 is adjusted to provide a capacitance variation value Δ C, and accordingly, the output voltage U of the inverter can be obtained_ABAnd an output current I₁The following relations are provided:

where M is the mutual inductance between the transmitter coil L1 and the receiver coil L2, ω₀Is the resonant angular frequency of the system.

As can be seen from the above equation, if the adjustment value Δ C <0 is set, i.e., the capacitance of the receiving-end correction capacitor Cm2 is decreased, the output impedance of the inverter 3 will be weakly inductive, which will change the current phase from the original resonant state to be synchronized with the voltage phase, to be slightly delayed by a certain angle. Before the switching tube is switched on, the output current of the inverter 3 is negative, the junction capacitors at two ends of the switching tube can complete charging and discharging in a dead time, and the anti-parallel diode of the other switching tube of the same bridge arm is conducted, so that the zero-voltage switching function is realized. Although setting the transmitting-side resonant network 4 to weak inductance increases a part of the reactive power of the system, the reactive power is small relative to the transmitted power and can be considered approximately in a resonant state.

When the electric automobile is charged wirelessly, the maximum transmission efficiency can be obtained when the transmitting coil L1 and the receiving coil L2 are completely aligned, and the horizontal direction of the transmitting coil and the receiving coil tends to have a certain offset when the electric automobile is parked, and meanwhile, the air gap distance between the transmitting coil L1 and the receiving coil L2 in the vertical direction can be changed due to the change of the load in the automobile, and the self inductance and the mutual inductance of the transmitting coil L1 and the receiving coil L2 can be changed due to the offset and the air gap change.

When the wireless charging circuit works, parasitic inductance and capacitance in the circuit can be increased due to high-frequency current in the circuit, and parameters of devices in the resonant network can be changed due to temperature rise; in addition, the impedance reflected from the receiving terminal Rx to the transmitting terminal Tx changes while the load impedance is changing during the charging process, and both of these conditions may cause the resonant frequency to deviate from the selected operating frequency, so that the maximum transmission efficiency and the stable operation of the system cannot be ensured.

The above problems can be solved by the correction device as well. The adjustment of the total inductance value of the sum of the total capacitance in the resonant circuit is realized by correcting the inductance and the capacitance, so that the wireless charging can reach a resonant state when working at the selected fixed working frequency.

During wireless charging, the change of the correction inductor or the correction capacitor can be dynamically adjusted by combining with a control strategy of a system, so that the resonant network is kept at the selected fixed working frequency, and the two sides of the transmitting end Tx and the receiving end Rx are in a resonant state and a weak-inductive working state.

In addition, the electric vehicle may have a plurality of charging sites in actual use, and the aforementioned method of selecting the operating frequency f0 may not allow its harmonics to avoid the medium-frequency channels of all sites nationwide or worldwide without any overlap. Therefore, the operating frequency can be set according to the medium wave broadcast frequency bands of different charging sites, the operating frequency is selected at one site according to the method, and the operating frequency value which does not interfere with the medium wave channel at each site is determined and then is prestored at the wireless charging transmitting end or the wireless charging receiving end or in the wireless charging management system.

Or before the system starts working, the working frequency is determined according to the medium wave frequency band of the place, the working frequency selection value of the place is interacted through the transmitting end communication module 6 and the receiving end communication module 12, and the corresponding numerical value of the correcting device is adjusted according to the selected working frequency, so that the system is in the working state of approximate resonance and weak sensitivity according to the set working frequency, and the maximum efficiency transmission and the lowest interference noise are obtained.

The construction, features and functions of the present invention are described in detail in the embodiments illustrated in the drawings, which are only preferred embodiments of the present invention, but the present invention is not limited by the drawings, and all equivalent embodiments modified or changed according to the idea of the present invention should fall within the protection scope of the present invention without departing from the spirit of the present invention covered by the description and the drawings.

Claims

1. Wireless charging system, divided into a transmitting end (Tx) and a receiving end (Rx), at which transmitting end (Tx) there is an inverter (3) and a transmitting end resonant network (4), the transmitting end resonant network (4) comprising at least a transmitting coil (L1) and a first capacitance (C1), at which receiving end (Rx) there is a rectifier (8) and a receiving end resonant network (7), the receiving end resonant network comprising at least a receiving coil (L2) and a second capacitance (C2), characterized in that,

at least one of the transmitting end (Tx) and the receiving end (Rx) has a correction device, which is one or both of a correction inductance and a correction capacitance;

when the correction device is a correction inductor, providing a variable inductance value to the terminal;

when the correction device is a correction capacitor, providing a variable capacitance value to the terminal;

the receiving terminal (Rx) has the correction capacitor, and the correction capacitor provided at the receiving terminal (Rx) is: a receiver correction capacitor (Cm 2), the receiver correction capacitor (Cm 2) providing a capacitance change value Δ C, the receiver correction capacitor (Cm 2) being connected in parallel with the second capacitor (C2);

current I output by the inverter (3)₁Comprises the following steps:

wherein,

U_ABis the output voltage of the inverter (3); u shape_abIs the input voltage of the rectifier (8);

ω₀is the resonant angular frequency of the system; m is the mutual inductance.

2. The wireless charging system of claim 1,

when the correction device is a correction inductor and is disposed at the transmitting end (Tx), the correction inductor is connected to the transmitting coil (L1);

when the correction device is a correction inductor and is arranged at the receiving end (Rx), the correction inductor is connected with the receiving coil (L2);

when the correction device is a correction capacitor and is disposed at the transmission end (Tx), the correction capacitor is connected to the first capacitor (C1);

when the correction device is a correction capacitor and is provided at the receiving end (Rx), the correction capacitor is connected to the second capacitor (C2).

3. The wireless charging system of claim 2,

when the correction device is a correction inductance and is disposed at the transmission end (Tx), the correction inductance is connected in series with the transmission coil (L1);

when the correction device is a correction inductor and is arranged at the receiving end (Rx), the correction inductor is connected in series with the receiving coil (L2);

when the correction device is a correction capacitor and is disposed at the transmission end (Tx), the correction capacitor is connected in parallel with the first capacitor (C1);

when the correction device is a correction capacitor and is provided at the receiving end (Rx), the correction capacitor is connected in parallel with the second capacitor (C2).

4. The wireless charging system according to any one of claims 1 to 3,

the transmitting terminal (Tx) is provided with the correcting inductor and the correcting capacitor, and the correcting capacitor arranged at the transmitting terminal (Tx) is as follows: a transmitting end correction capacitor (Cm 1); the correction inductance provided at the transmitting end (Tx) is: a transmitting end correction inductor (Lm 1);

the receiving terminal (Rx) further has the correction inductor, and the correction inductor provided at the receiving terminal (Rx) is: the receiving end corrects the inductance (Lm 2);

the transmitting end correction capacitor (Cm 1) is connected with the first capacitor (C1) in parallel;

the transmitting end correction inductor (Lm 1) is connected with the transmitting coil (L1) in series;

the receiving end correction inductor (Lm 2) is connected with the receiving coil (L2) in series.

5. The wireless charging system of claim 1,

when the capacitance change value deltaC is less than 0, the current output by the inverter (3) generates a phase.

6. The wireless charging system of claim 1,

the metal-oxide semiconductor field effect transistor switching tube of the inverter (3) is as follows: zero voltage switching and/or zero current switching.

7. The wireless charging system of claim 1,

the operating frequency is in the gap between the Lower Sideband (LSB) and the Upper Sideband (USB) of the electromagnetic field in the environment.

8. The wireless charging system according to claim 1 or 7,

the working frequency is 79-90 kHz.

9. The wireless charging system of claim 1,

when the correction device is a correction inductor, said correction inductor having a control Input Port (IP) for controlling a variation of the inductance value;

when the correction device is a correction capacitor, the electrolyte of the magnetorheological fluid is filled between the polar plates of the correction capacitor, and the coils are wound outside the polar plates.