CN112421794A - Wireless charging circuit, chargeable equipment and wireless charging system - Google Patents

Abstract

The present application provides a wireless charging circuit, a chargeable device and a wireless charging system, which relate to the technical field of charging management. The wireless charging circuit is applied to a rechargeable device, and the wireless charging circuit includes: at least two wireless charging receiving branches and at least two rectifying circuits; wherein the output end of each wireless charging receiving branch is electrically connected to the wireless charging receiving branch through a rectifying circuit. A battery of a rechargeable device; each wireless charging receiving branch is used to receive energy generated by a wireless transmitting branch in a wireless charger corresponding to the rechargeable device; in at least two wireless charging receiving branches, there is a first wireless charging branch A first compensation capacitor connected in series between the first receiving inductance of the receiving branch and the first output terminal, in at least two wireless charging receiving branches, there are the second receiving inductance and the second output terminal of the second wireless charging receiving branch LCC resonant circuit in parallel between. By applying the embodiments of the present invention, the reliability of wireless charging of the battery is improved.

Description

A wireless charging circuit, rechargeable device and wireless charging system

technical field

The present application relates to the technical field of charging management, and in particular, to a wireless charging circuit, a chargeable device and a wireless charging system.

Background technique

Inductive Power Transfer (IPT, Inductive Power Transfer) is a charging technology that can transmit energy through the air gap between the transmitter and the receiver without physical contact. Electronic equipment charging and biopharmaceutical implantable component charging and other fields.

The battery charging stage can include constant current charging stage and constant voltage charging stage. In the early stage of battery charging, the constant current charging mode is adopted. Even if the battery enters the constant current charging stage, the voltage of the battery terminal rises rapidly. When the voltage is constant, the battery adopts the constant voltage charging mode, even if the battery enters the constant voltage charging stage, the charging current in this stage is gradually reduced to the cut-off charging current.

At present, the wireless charging system mainly obtains the battery charging information through the state-of-charge detection device, and sends the charging information to the transmitter-side controller through the feedback system. Enter the constant voltage charging stage.

However, because the existing wireless charging system needs to change the operating frequency of the inverter through software control and switch the charging stage of the battery, the phenomenon of frequency bifurcation may occur, which will reduce the reliability of wireless charging of the battery. .

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a wireless charging circuit, a rechargeable device and a wireless charging system in view of the above-mentioned deficiencies in the prior art, which can improve the reliability of wireless charging of a battery.

To achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

In a first aspect, an embodiment of the present application provides a wireless charging circuit, which is applied to a rechargeable device. The wireless charging circuit includes: at least two wireless charging receiving branches and at least two rectifying circuits; wherein each wireless charging circuit includes: The output end of the receiving branch is electrically connected to the battery of the rechargeable device through a rectifier circuit; each wireless charging receiving branch is used to receive the wireless transmission branch in the wireless charger corresponding to the rechargeable device. energy;

In the at least two wireless charging receiving branches, there is a first compensation capacitor connected in series between the first receiving inductance of the first wireless charging receiving branch and the first output terminal, and in the at least two wireless charging receiving branches , there is an LCC resonant circuit connected in parallel between the second receiving inductor of the second wireless charging receiving branch and the second output end.

Optionally, the LCC resonant circuit includes: two second compensation capacitors and one compensation inductance; wherein, a first end of the second receiving inductance is electrically connected to one end of a second compensation capacitor, and the second receiving inductance The second end of the second compensation capacitor is electrically connected to one end of another second compensation capacitor, and the other end of the one second compensation capacitor is electrically connected to one end of the compensation inductance;

The other end of the one second compensation capacitor is also electrically connected to the other end of the other second compensation capacitor;

The other end of the compensation inductance is the positive output end of the second output end, and the second end of the second receiving inductance is the negative output end of the second output end.

Optionally, the wireless charging circuit further includes: a filter capacitor; one end of the filter capacitor is electrically connected to the positive electrode of the battery, and the other end of the filter capacitor is electrically connected to the negative electrode of the battery.

Optionally, the number of the wireless charging receiving branches is two, and each wireless charging receiving branch is connected to a rectifier circuit.

In a second aspect, an embodiment of the present application provides a rechargeable device, including a battery and the wireless charging circuit in the first aspect; an output end of each wireless charging receiving branch in the wireless charging circuit is connected to the battery.

In a third aspect, an embodiment of the present application provides a wireless charging system, including the rechargeable device and the wireless charger of the second aspect;

Each wireless charging receiving branch in the rechargeable device is configured to receive energy generated by a wireless transmitting branch in the wireless charger, so as to wirelessly charge the battery in the rechargeable device.

Optionally, a third compensation capacitor is connected in series between the wireless transmission inductance of the wireless transmission branch and the output end of the inverter in the wireless charger.

The beneficial effects of this application are:

Embodiments of the present application provide a wireless charging circuit, a rechargeable device, and a wireless charging system. The wireless charging circuit is applied to a rechargeable device, and the wireless charging circuit includes: at least two wireless charging receiving branches and at least two rectifying circuits; Wherein, the output end of each wireless charging receiving branch is electrically connected to the battery of the charging device through a rectifier circuit; each wireless charging receiving branch is used for receiving the wireless transmitting branch in the wireless charger corresponding to the rechargeable device to generate energy; in at least two wireless charging receiving branches, there is a first compensation capacitor connected in series between the first receiving inductance of the first wireless charging receiving branch and the first output terminal, and in at least two wireless charging receiving branches, There is an LCC resonance circuit connected in parallel between the second receiving inductor of the second wireless charging receiving branch and the second output terminal. Using the wireless charging circuit provided by the embodiment of the present application, through the first wireless charging receiving branch with series compensation, the second wireless charging receiving branch with LCC resonance compensation, and the rectifier circuit, the wireless transmitting branch in the wireless charger can be converted into The magnetic energy generated by the circuit is converted into electric energy and output in the form of constant current/constant voltage. With the passage of charging time, the battery can be converted from constant current charging mode to constant voltage charging mode based on a working frequency point, avoiding the working frequency The phenomenon of bifurcation occurs, which improves the reliability of wireless charging of the battery.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a wireless charging circuit according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of another wireless charging circuit provided by an embodiment of the present application;

FIG. 3 is an equivalent circuit model of a wireless charging circuit provided by an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a wireless charging system according to an embodiment of the present application;

Fig. 5 is the circuit schematic diagram corresponding to the constant current charging mode;

Fig. 6 is the circuit schematic diagram corresponding to the constant voltage charging mode;

FIG. 7 is a voltage and current simulation working waveform diagram corresponding to a constant current charging mode;

FIG. 8 is a voltage and current simulation working waveform diagram corresponding to a constant voltage charging mode;

FIG. 9 is a graph of the current and voltage changes of the simulated output under different _RL conditions.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "arrangement", "installation", "connection" and "connection" should be interpreted in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific situations.

FIG. 1 is a schematic structural diagram of a wireless charging circuit according to an embodiment of the present application. As shown in Figure 1, the wireless charging circuit is applied to a charging device. The rechargeable device can be a terminal that needs to be charged, such as a mobile phone, a tablet computer, a wearable device, etc., or other devices that need to be charged, such as an electric vehicle etc., which are not limited in this application, the wireless charging circuit may include:

At least two wireless charging receiving branches and at least two rectifying circuits, wherein the output end of each wireless charging receiving branch is electrically connected to the battery of the rechargeable device through a rectifying circuit; each wireless charging receiving branch is used to receive the The energy generated by the wireless transmission branch 101 in the wireless charger corresponding to the rechargeable device.

In the at least two wireless charging receiving branches, there is a first compensation capacitor _Cb connected in series between the first receiving inductance L _b of the first wireless charging receiving branch 102 and the first output terminal, and the at least two wireless charging receiving branches Among them, there is an LCC resonant circuit D connected in parallel between the second receiving inductance L _c of the second wireless charging receiving branch 103 and the second output terminal.

Specifically, the wireless transmitting branch 101 can convert the high-frequency alternating current output by the inverter H into a high-frequency alternating magnetic field, and the first receiving inductance L _b in the first wireless charging receiving branch 102 is in the high-frequency alternating magnetic field. The induced electromotive force is induced in the middle, thereby generating high-frequency alternating current. The high-frequency alternating current is converted into direct current after passing through the first rectifier circuit 104 , and provides electrical energy to the battery 105 . Similarly, the second receiving inductance L _c in the second wireless charging receiving branch 103 induces an induced electromotive force in the high-frequency alternating magnetic field, thereby generating high-frequency alternating current, which is converted by the second rectifier circuit 106 . DC power is supplied to the battery 105. That is to say, the process of charging the battery 105 is equivalent to the process of converting electrical energy into magnetic energy, and then converting the magnetic energy into electrical energy.

One end of the inverter H is connected to the DC power supply _VI , and the other end is connected to the wireless transmitting branch 101. The inverter H can be composed of a field effect transistor, and is used to _invert the DC power output by the DC power supply VI to a working frequency of f The specific form of the alternating current can be a sine wave or a square wave, which is not limited in this application. The wireless transmission branch 101 has a wireless transmission inductance _La and a third compensation capacitor C _a connected in series with the output end of the inverter H, the wireless transmission inductance L _a , the first receiving inductance L _b and the second receiving inductance A mutual inductance coil is formed between L and _c .

The specific parameter values (L _a , _Ca , L _b , C _{b )} of the wireless transmitting inductance La , the third compensation capacitor C _a , the first receiving inductance L _b and the first compensation capacitor C _b can be determined by the following formula.

Among them, the self-inductance coefficients of the wireless transmitting inductance L _a and the first receiving inductance L _b are represented by _La and L _b respectively, and the unit is often represented by Henry ₍ H ₎ . The capacitance coefficients are represented by C _a and C _b respectively, and the unit is often represented by Farads (F); ω is the working angular frequency, and the relationship between it and the working frequency f is ω=2πf.

表示，输出LCC谐振电路的电流用i_c表示，第二输出端侧的电压用v_c表示，第二输出端侧的等效电阻用R_eq，c表示。The current on the first wireless charging receiving branch 102 is represented by i _b , the voltage on the first output side is represented by v _b , and the equivalent resistance on the first output side is represented by Re _eq.b ; the current input to the LCC resonant circuit use

represents, the current of the output LCC resonant circuit is represented by ic, the voltage on the side of the second output terminal is represented by _vc , and the equivalent resistance on the side of the second output terminal is represented by Re _{eq,c .}

It can be seen from the circuit connections described above that the wireless transmitting branch 101 and the first wireless charging receiving branch 102 are respectively series compensation, and the second wireless charging receiving branch 103 is LCC resonance compensation. According to the circuit principle, the current i _b on the first wireless charging receiving branch 102 is inversely proportional to the product of the equivalent resistance Re _eq.b on the first output side and the equivalent resistance Re _eq,c on the second output side , the voltage v _c on the second output side is proportional to the product of the equivalent resistance Re _eq.b on the first output side and the equivalent resistance Re _eq,c on the second output side.

At the beginning of charging, the current i _b on the first wireless charging receiving branch 102 is relatively large, so the voltage v _b on the first output end side is relatively large, and as the charging time goes on, the equivalent of the first output end side The resistance Re _eq.b and the equivalent resistance Re _eq,c on the side of the second output terminal gradually increase, and the voltage _vc on the side of the second output terminal increases.

According to the clamping characteristic of the rectifier circuit, it can be approximately considered that the voltage _VO supplied to the battery 105 is determined by the wireless charging receiving branch outputting a higher voltage (v _b or _vc ). That is to say, in the early stage of charging, the voltage v _b on the first output side is greater than the voltage _vc on the second output side, which is equivalent to the second wireless charging receiving branch 103 being blocked, and the series-series compensation circuit (wireless The transmitting branch 101 and the first wireless charging receiving branch 102) charge the battery ₁₀₅ , and the battery ₁₀₅ is in a constant current charging mode. The relationship between v and _b is:

As the charging time goes on, the voltage v _c on the second output terminal side gradually increases. When the voltage v _b on the first output terminal side is smaller than the voltage v _c on the second output terminal side, it is equivalent to the first wireless charging receiving branch. The circuit 102 is blocked, and the series-LCC resonance compensation circuit (wireless transmitting branch 101 and the second wireless charging receiving branch 103) is used to charge the battery 105. At this time, the battery 105 is in the constant voltage charging mode. When the voltage V _O at the terminal of the battery 105 remains unchanged, the current I _O gradually decreases, and when it decreases to the cut-off charging current, it proves that the battery 105 has been fully charged.

Using the wireless charging circuit shown in FIG. 1, the wireless charging circuit is applied to charging equipment, and the wireless charging circuit includes: at least two wireless charging receiving branches and at least two rectifying circuits; wherein, each wireless charging receiving branch The output end of the charging device is electrically connected to the battery of the charging device through a rectifier circuit; each wireless charging receiving branch is used to receive the energy generated by the wireless transmitting branch in the wireless charger corresponding to the charging device; at least two wireless charging receiving branches In the circuit, there is a first compensation capacitor connected in series between the first receiving inductance of the first wireless charging receiving branch and the first output terminal, and in at least two wireless charging receiving branches, there is a first compensation capacitor of the second wireless charging receiving branch. Two LCC resonant circuits connected in parallel between the receiving inductor and the second output terminal. Using the wireless charging circuit provided by the embodiment of the present application, through the first wireless charging receiving branch with series compensation, the second wireless charging receiving branch with LCC resonance compensation, and the rectifier circuit, the wireless transmitting branch in the wireless charger can be converted into The magnetic energy generated by the circuit is converted into electric energy and output in the form of constant current/constant voltage. With the passage of charging time, the battery can be converted from constant current charging mode to constant voltage charging mode based on a working frequency point, avoiding the working frequency The phenomenon of bifurcation occurs, which improves the reliability of wireless charging of the battery.

FIG. 2 is a schematic structural diagram of another wireless charging circuit according to an embodiment of the present application. As shown in FIG. 2 , the LCC resonant circuit includes: two second compensation capacitors (C _c,1 , C _c,2 ) and one compensation inductance L _c,3 ; wherein, the first terminal of the second receiving inductance L _c One end of a second compensation capacitor C _{c, 1} is connected, the second end of the second receiving inductor L _c is electrically connected to one end of another second compensation capacitor C _{c, 2} , and the other end of a second compensation capacitor C _{c, 1} One end of the compensation inductance L _c,3 is electrically connected.

The other end of a second compensation capacitor C _{c, 1} is also electrically connected to the other end of another second compensation capacitor C _{c, 2;} the other end of the compensation inductance L _{c, 3} is the positive output end of the second output end, the second receiving The second terminal of the inductor L _c is the negative output terminal of the second output terminal.

The relationship between the second receiving inductance L _c , the two second compensation capacitors (C _c,1 , C _c,2 ), the compensation inductance L _c,3 and the working angular frequency ω can be expressed by the following formula:

The wireless transmitting inductance L _a on the wireless transmitting branch 101 , the first receiving inductance L _b on the first wireless charging receiving branch 102 , and the second receiving inductance L _c on the second wireless charging receiving branch 103 , two There is a mutual inductance coefficient between M _ab , M _ac , and M _bc respectively, where M _bc is close to 0, that is, the coupling between the first receiving inductance L _b and the second receiving inductance L _c may be zero.

It can be seen from the connection relationship of the components on the second wireless charging receiving branch 103 in FIG. 2 that the second wireless charging receiving branch 103 can be equivalent to a pure resistance transformation dual-port network, which can be expressed by the following formula:

Among them, jωM _ac i _a is the induced voltage of the second receiving inductor L _c , γ is the two second compensation capacitors (C _c,1 , C _c,2 ) and a compensation inductor L _c,3 on the LCC resonant circuit The relevant transimpedance can be expressed as:

为无线发射支路101到第一无线充电接收支路102的反射电阻；

为无线发射支路101FIG. 2 can be approximately equivalent to the circuit model of FIG. 3 . FIG. 3 is an equivalent circuit model of a wireless charging circuit provided by an embodiment of the present application. As shown in Figure 3,

is the reflection resistance from the wireless transmitting branch 101 to the first wireless charging receiving branch 102;

For the wireless transmission branch 101

Reflect resistance to the second wireless charging receiving branch 103; i _a is the current at the output end of the inverter H, va is the voltage at the output end of the inverter H, and jωM _{a b} i _a is the induced voltage of the first receiving inductor L _b .

As can be seen from Figure 3, the input impedance is purely resistive, and no matter how the load changes, a zero-phase input can be achieved, which can reduce reactive power, that is, reduce power loss, and minimize the voltage-ampere rating, which is Battery charging provides great reliability.

可用下式表示：Among them, the emission resistance

It can be represented by the following formula:

The voltage va at the output end of the inverter H, the current _ib on the first wireless charging receiving branch, and the voltage _vc on the second output end can be deduced, where _va , _ib , and _{vc can} be respectively adopted as follows: formula means:

The equivalent resistance on the battery 105 side in FIG. 2 is represented by _RL , and the relationship between _RL and _Req,b , _Req,c is:

According to the clamping characteristics of the rectifier circuits (the first rectifier circuit 104 and the second rectifier circuit 106 in FIG. 2 ), it can be approximately considered that the voltage _VO supplied to the battery 105 is determined by the output voltage (v b or vc ) of the higher voltage (v _b or _vc ) output is determined.

The following is an analysis of the wireless charging circuit in FIG. 2 to realize the constant current charging mode and the constant voltage charging mode.

Since the wireless transmitting branch 101 and the first wireless charging receiving branch 102 use series compensation, and the second wireless charging receiving branch 103 uses LCC resonant circuit compensation, in the early stage of charging the battery 105, the first wireless charging receiving branch The current i _b on the branch 102 is a relatively large current, the current i _c of the output LCC resonant circuit is a current close to 0, the voltage v _b on the first output terminal side is greater than the voltage v _c on the second output terminal side, According to the clamping characteristic of the rectifier circuit, the second output terminal is equivalent to being blocked.

在该恒流充电模式，电池105端的电压V_O上升，其中，V_O和v_b之间的关系为：

It can be seen that the battery 105 is charged by the series-series compensation circuit (the wireless transmitting branch 101 and the first wireless charging receiving branch 102 ), and the battery 105 is in the constant current charging mode. The constant current _IO input to the battery 105 can be expressed as:

In this constant current charging mode, the voltage V _O at the battery 105 terminal rises, wherein the relationship between V _O and v _b is:

以及公式

可以看出，第一无线充电接收支路102上的电流i_b逐渐减小，第二输出端侧的电压v_c逐渐增大，当v_c大于v_b时，再根据整流电路的箝位特性，第一输出端相当于被阻塞。As the charging time goes on, the equivalent resistance Re _eq.b on the first output side and the equivalent resistance Re _{eq, c} on the second output side increase respectively, and then according to the formula

and the formula

It can be seen that the current i _b on the first wireless charging receiving branch 102 gradually _decreases , and the voltage _vc on the second output side gradually increases _. , the first output is equivalent to being blocked.

在该恒压充电模式，输入电池105端的电流I_O逐渐降低。It can be seen that the battery 105 is charged by the circuit compensated by the series-LCC resonant circuit (the wireless transmitting branch 101 and the second wireless charging receiving branch 103 ), and the battery 105 is in the constant voltage charging mode at this time. Next, the constant voltage V _O input to the battery 105 can be expressed as:

In this constant voltage charging mode, the current _IO input to the terminal of the battery 105 gradually decreases.

According to the above analysis, the conversion of the wireless charging circuit in Figure 2 from the constant current charging mode to the constant voltage mode can be analyzed by resistance, then the conversion boundary _{RL, boundary} can be expressed by the following formula:

That is to say, when the equivalent resistance _RL on the side of the battery 105 is smaller than _{RL, boundary} , the battery 105 is in the constant current charging mode, and _IO is a fixed value. As the charging time goes on, _RL will change with the charge. As the state increases, the battery 105 is in constant voltage charging mode when _RL is not less than _RL,boundary .

Optionally, the wireless charging circuit in FIG. 2 further includes: a filter capacitor C _f ; one end of the filter capacitor C _f is electrically connected to the positive electrode of the battery 105 , and the other end of the filter capacitor C _f is electrically connected to the negative electrode of the battery 105 .

Optionally, the filter capacitor C _f is a capacitor with polarity, the positive electrode of the filter capacitor C _f is electrically connected to the positive electrode of the battery 105 , and the negative electrode of the filter capacitor C _f is electrically connected to the negative electrode of the battery 105 .

It can be seen that the filter capacitor has the function of filtering, which can further improve the reliability of charging the battery.

It should be noted that the constant current, constant voltage and operating frequency required by the battery 105 are all known parameters. According to the above formula, the parameters of each component on the wireless charging circuit (such as L _a , C _a , L _b ) can be determined , C _b ).

The present application also provides a charging device, the chargeable device may include the wireless charging circuit mentioned in the above embodiments, and the output end of each wireless charging receiving branch in the wireless charging circuit is connected to a battery. The charging device may specifically be a terminal that needs to be charged, such as a mobile phone, a tablet computer, a wearable device, etc., or other devices that need to be charged, such as an electric vehicle, which is not limited in this application.

FIG. 4 is a schematic structural diagram of a wireless charging system according to an embodiment of the present application. As shown in FIG. 4 , the system includes a wireless charger 400 and a rechargeable device 500 , and each wireless charging receiving branch in the rechargeable device 500 (a first wireless charging receiving branch 102 and a second wireless charging receiving branch 103 ) It is used to receive the energy generated by the wireless transmission branch 101 in the wireless charger 400 to wirelessly charge the battery 105 in the rechargeable device 500 .

Specifically, the wireless charger 400 may include a DC power supply _VI , an inverter H, and a wireless transmission branch 101. One end of the inverter H is connected to the DC power supply _VI , and the other end is connected to the wireless transmission branch 101. The inverter H can be specifically composed of four field effect transistors (Q ₁ , Q ₂ , Q ₃ , Q ₄ ), and inverts the DC voltage output by the DC power supply _VI into an AC current va with an operating frequency _f . The wireless transmission branch 101 includes a third compensation capacitor C _a , a wireless transmission inductance La and _a first equivalent resistance _Ra , which are connected in series in sequence. The first equivalent resistance _Ra is _a parasitic resistance of the wireless transmission inductance La, and the inverter One end of the output end of the inverter H is connected to one end of the third compensation capacitor C _a , the other end of the output end of the inverter H is connected to one end of the first equivalent resistance R _a , and the wireless transmission branch 101 is used to convert the alternating current v _a to high Frequency alternating magnetic field.

The rechargeable device 500 may include a first wireless charging receiving branch 102 , a second wireless charging receiving branch 103 , a first rectifier circuit 104 , a second rectifier circuit 106 , a battery 105 , a filter capacitor C _f , and a first rectifier circuit. One end of 104 is connected to the first wireless charging receiving branch 102 , the other end is connected to the filter capacitor C _f , and the filter capacitor C _f is connected to the battery 105 , wherein the first wireless charging receiving branch 102 includes a first receiving inductor L _b connected in series. , the first compensation capacitor C _b , the second equivalent resistance R _b , the second equivalent resistance R _b is the parasitic resistance of the first receiving inductance L _b , the first rectifier circuit 104 is specifically composed of four diodes, the first rectifier circuit One end of the input end of 104 is connected to one end of the first compensation capacitor _Cb , the other end of the input end of the first rectifier circuit 104 is connected to one end of the second equivalent resistor _Rb , and one end of the output end of the first rectifier circuit 104 is connected to the filter capacitor _Cf. The positive pole is connected to the positive pole of the filter capacitor C _f , the positive pole of the filter capacitor C _f is connected to the positive pole of the battery 105 , and the negative pole of the filter capacitor C _f is connected to the negative pole of the battery 105 .

One end of the second rectifier circuit 106 is connected to the second wireless charging receiving branch 103 , the other end is connected to a filter capacitor C _f , and the filtering capacitor C _f is connected to the battery 105 , wherein the second wireless charging receiving branch 103 includes a second receiving inductor L _c . The LCC resonant circuit, the third equivalent resistance R _c , the third equivalent resistance R _c is the parasitic resistance of the second receiving inductance L _c , and the LCC resonant circuit includes a second compensation capacitor (C _c,1 , C _{c,2 )} ), compensation inductance Lc _,3 , one end of the second receiving inductance Lc is connected to a second compensation capacitor _{Cc ,1} , a second compensation capacitor _Cc,1 is connected to the compensation inductance Lc _,3 , the other One end of the two compensation capacitors C _{c, 2} is connected to the node between the second compensation capacitor C _{c, 1} and the compensation inductors L _{c, 3} , and the other end of the other second compensation capacitor C _{c, 2} is connected to the second receiving inductor L _c The other end of the second rectifier circuit 106 is specifically composed of four diodes, one end of the input end of the second rectifier circuit 106 is connected to one end of the compensation inductance Lc _{, 3} , and the other end of the input end of the second rectifier circuit 106 is connected to the third equivalent resistance One end of R _c is connected, one end of the output end of the first rectifier circuit 104 is connected to the positive electrode of the filter capacitor C _f , the other end is connected to the positive electrode of the filter capacitor C _f , the positive electrode of the filter capacitor C _{f is} connected to the positive electrode of the battery 105, and the The negative electrode is connected to the negative electrode of the battery 105 .

The content of realizing the conversion from the constant current charging mode to the constant current charging mode by the wireless charging system in FIG. 4 will not be analyzed in detail here. For details, please refer to the above description.

When the wireless charging system is in a constant current charging mode, a circuit schematic diagram corresponding to the constant current charging mode is shown in FIG. 5 . Figure 5 is a schematic diagram of the circuit corresponding to the constant current charging mode. It can be seen that when the wireless charging system is in the constant current charging mode, it is equivalent to using a series-series compensation circuit (the wireless transmitting branch 101 and the first wireless charging receiving branch). 102) to charge the battery 105.

When the wireless charging system is in a constant voltage charging mode, a circuit schematic diagram corresponding to the constant voltage charging mode is shown in FIG. 6 . Figure 6 is a schematic diagram of the circuit corresponding to the constant voltage charging mode. It can be seen that when the wireless charging system is in the constant voltage charging mode, it is equivalent to using the circuit compensated by the series-LCC resonant circuit (the wireless transmission branch and the second wireless charging The receiving branch 103) charges the battery 105.

It can be seen that the wireless charging system can only use hardware to charge the battery at one operating frequency, avoiding the complexity of the wireless charging system with software control. The wireless charging system can reduce the output of reactive power, that is, improve the power factor of the wireless charging system, thereby improving the reliability of multi-battery charging.

In order to verify the feasibility of the above wireless charging system, the wireless charging circuit can be designed using the component parameters in Table 1.

Table 1

Among them, k _ab , k _ac , k _bc represent the coupling coefficient between the wireless transmitting inductor _{La , the first receiving inductor L b ,} and the second receiving inductor L _c between the two coils, and the coupling coefficient (k _ab , k _ac , k _bc ) ) and mutual inductance coefficients (M _ab , M _ac , M _bc ) can be expressed by the following formula:

The wireless charging circuit designed according to the component parameters in Table 1 is simulated. The simulation results show that when the equivalent resistance _RL on the battery 105 side is less than 30Ω, the wireless charging system is in constant current charging mode. Figure 7 shows the voltage and current simulation waveforms corresponding to the constant current charging mode. As shown in Figure 7, the output current ic of the _LCC resonant circuit is very small, close to 0, which is equivalent to the second wireless charging receiving branch of the LCC resonance compensation. 103 is approximately blocked, the current _ib on the first wireless charging receiving branch 102 is larger than _ic , that is, the first wireless charging receiving branch 102 with series compensation enabled is used to charge the battery 105 .

When the equivalent resistance _RL on the side of the battery 105 is greater than 30Ω, the wireless charging system is in a constant voltage charging mode. FIG. 8 is a voltage and current simulation working waveform diagram corresponding to the constant voltage charging mode. As shown in FIG. 8 , the current i _b on the first wireless charging receiving branch 102 is very small, close to 0, which is equivalent to the first wireless charging in series compensation. The charging receiving branch 102 is approximately blocked, that is, the second wireless charging receiving branch 103 with LCC resonant circuit compensation enabled is used to charge the battery 105 .

And it can also be seen from the waveform diagrams of the voltage v _a and the current i _a at the output terminal of the inverter H in FIG. 7 and FIG. 8 that the zero phase of the voltage v _a and the zero phase of the current i _a approximately intersect, that is to say , the wireless charging system can reduce the output of reactive power and improve the power factor of wireless charging.

Figure 9 is a graph of the current and voltage changes of the simulated output under different _RL conditions. It can be seen from Figure 9 that when _RL is equal to 30Ω, the wireless charging system is converted from constant current charging mode to constant voltage charging mode , and output a constant current and constant voltage independent of the load.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (8)

1. A wireless charging circuit, applied to a chargeable device, the wireless charging circuit comprising: the wireless charging system comprises at least two wireless charging receiving branches and at least two rectifying circuits; the output end of each wireless charging receiving branch circuit is electrically connected with a battery of the rechargeable equipment through a rectifying circuit; each wireless charging receiving branch is used for receiving wireless energy generated by a wireless transmitting branch in a wireless charger corresponding to the charging equipment;

in the at least two wireless charging receiving branches, a first compensation capacitor connected in series between a first receiving inductor and a first output end of a first wireless charging receiving branch exists, and in the at least two wireless charging receiving branches, an LCC resonant circuit connected in parallel between a second receiving inductor and a second output end of a second wireless charging receiving branch exists.

2. The wireless charging circuit of claim 1, wherein the LCC resonant circuit comprises: two second compensation capacitors and one compensation inductor; the first end of the second receiving inductor is electrically connected with one end of one second compensation capacitor, the second end of the second receiving inductor is electrically connected with one end of the other second compensation capacitor, and the other end of the one second compensation capacitor is electrically connected with one end of the compensation inductor;

the other end of the second compensation capacitor is also electrically connected with the other end of the other second compensation capacitor;

the other end of the compensation inductor is a positive output end of the second output end, and the second end of the second receiving inductor is a negative output end of the second output end.

3. The wireless charging circuit of claim 1 or 2, further comprising: a filter capacitor; one end of the filter capacitor is electrically connected with the positive electrode of the battery, and the other end of the filter capacitor is electrically connected with the negative electrode of the battery.

4. The wireless charging circuit of claim 3, wherein the filter capacitor is a capacitor having a polarity, a positive electrode of the filter capacitor is electrically connected to a positive electrode of the battery, and a negative electrode of the filter capacitor is electrically connected to a negative electrode of the battery.

5. The wireless charging circuit according to claim 1, wherein the number of the wireless charging receiving branches is two, and each wireless charging receiving branch is connected with a rectifying circuit.

6. A rechargeable device comprising a battery and a wireless charging circuit as claimed in any one of claims 1 to 5; the output end of each wireless charging receiving branch in the wireless charging circuit is connected with the battery.

7. A wireless charging system, comprising: the chargeable device of claim 6 and a wireless charger;

each wireless charging receiving branch in the chargeable device is used for receiving energy generated by a wireless transmitting branch in the wireless charger so as to wirelessly charge a battery in the chargeable device.

8. The wireless charging system of claim 7, wherein a third compensation capacitor is connected in series between the wireless transmitting inductor of the wireless transmitting branch and the output terminal of the inverter in the wireless charger.

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