Charging circuit and electronic device

Abstract

The present application relates to a charging circuit and an electronic device. The charging circuit comprises a resonant circuit, a transformer and a plurality of charging branches, wherein each charging branch comprises a battery needing to be charged; the transformer comprises a primary winding and a plurality of secondary winding units, the plurality of secondary winding units corresponding to the plurality of charging branches on a one-to-one basis, and each secondary winding unit comprising at least one secondary winding; an input end of the resonant circuit is connected to an external power supply source, and an output end of the resonant circuit is connected to the primary winding; and each secondary winding unit is connected to the corresponding charging branch, so as to charge the battery in the charging branch. By using the charging circuit, the charging reliability can be improved.

Description

Charging circuit and electronic device

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024104656206, filed on April 17, 2024, and entitled "Charging circuit and electronic device", the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of charging, in particular to a charging circuit and an electronic device. BACKGROUND

[0004] With the increasing requirement of intelligent devices on charging speed, the output power of the adapter is also increasing, which puts higher requirements on the reliability of the charging circuit.

[0005] At present, the battery in the intelligent device is charged by the charge pump in the adapter and the intelligent device.

[0006] However, with the increasing output power of the adapter, when the switch tube inside the charge pump ages over time, the switch tube is prone to breakdown and other failures, which can cause the high output voltage to directly flow into the battery, resulting in the risk of battery fire. Therefore, the current charging circuit has the problem of low charging reliability. SUMMARY

[0007] Therefore, it is necessary to provide a charging circuit and an electronic device capable of improving charging reliability in view of the above technical problems.

[0008] In a first aspect, the present application provides a charging circuit, which comprises a resonant circuit, a transformer and a plurality of charging branches, each charging branch comprising a battery to be charged, the transformer comprising a primary winding and a plurality of secondary winding units, the plurality of secondary winding units corresponding to the plurality of charging branches one by one, and each secondary winding unit comprising at least one secondary winding; the input end of the resonant circuit is connected with an external power supply, and the output end of the resonant circuit is connected with the primary winding; each secondary winding unit is connected with the corresponding charging branch to charge the battery in the charging branch.

[0009] In a second aspect, the present application further provides an electronic device comprising the charging circuit according to any one of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only need to explain the present application, and for those skilled in the field, other drawings can be obtained based on the disclosed drawings without any creative effort.

[0011] FIG. 1 is a schematic diagram of a charging architecture of a charge pump circuit in the related art;

[0012] FIG. 2A is a schematic diagram of a first half cycle of a working cycle of a charge pump circuit in the related art;

[0013] FIG. 2B is a schematic diagram of a second half cycle of a working cycle of a charge pump circuit in the related art;

[0014] FIG. 3A is a schematic diagram of a charging architecture of a single battery in the related art;

[0015] FIG. 3B is a schematic diagram of a charging architecture of a double battery in the related art;

[0016] FIG. 4 is a charging circuit in an embodiment;

[0017] FIG. 5 is a charging branch in an embodiment;

[0018] FIG. 6 is another charging branch in an embodiment;

[0019] FIG. 7 is still another charging branch in an embodiment;

[0020] FIG. 8 is a switching circuit in an embodiment;

[0021] FIG. 9 is another charging circuit in an embodiment;

[0022] FIG. 10 is a bridge circuit in an embodiment;

[0023] FIG. 11 is another bridge circuit in an embodiment;

[0024] FIG. 12 is a resonant circuit in an embodiment;

[0025] FIG. 13 is a control circuit in an embodiment;

[0026] FIG. 14 is another charging circuit in an embodiment;

[0027] FIG. 15 is still another charging circuit in an embodiment;

[0028] FIG. 16 is a multi-battery series charging circuit in an embodiment;

[0029] FIG. 17 is a voltage-current waveform diagram of a charging circuit in one embodiment;

[0030] FIG. 18 is a voltage-current waveform diagram of another charging circuit in one embodiment;

[0031] FIG. 19 is a charge and discharge circuit in one embodiment. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0034] It can be understood that the terms "first", "second", and the like used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first resistor can be referred to as the second resistor, and similarly, the second resistor can be referred to as the first resistor. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0035] It can be understood that "connection" in the following embodiments means "electrical connection", "communication connection", etc. if the circuits, modules, units, etc. connected to each other have transmission of electrical signals or data.

[0036] It can be understood that "at least one" means one or more, and "multiple" means two or more. "At least part of the element" means part or all of the element.

[0037] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", or the like, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

[0038] With the increasing demand for charging speed of intelligent devices such as smart phones, the output power of adapters and chargers is also increasing, such as from previous 5W-10W-15W-20W-65W-120W-150W. The popular charging communication protocols at present are VOOC (flash charging), PPS (Programmable Power Supply), PD (Power Delivery), etc., among which VOOC and PPS are direct charging modes, and PD is a constant voltage charging mode. In order to unify the interface specification, it is stipulated that these charging communication protocols are applicable to type "C" port. According to the current overcurrent capacity of C port, it is generally limited to 5A, but it still cannot meet the increasing demand of people for charging speed.

[0039] Referring to the CP charging architecture diagram in the related art shown in FIG. 1, it includes an adapter, a CP (Charge Pump) and a double series battery pack, wherein the CP and the double series battery pack are arranged in an intelligent device, the output voltage is 40V, and the output current is 5A. After processing by the CP, the output voltage becomes 10V, and the output current becomes 20A.

[0040] Among them, the CP circuit is to charge the capacitor by continuously opening the switch, and to re-distribute the charge of the capacitor by closing the switch to achieve halving of the output voltage, and to provide the halved output voltage to the battery for charging. Referring to the circuit diagrams shown in FIG. 2A and FIG. 2B, wherein FIG. 2A is a working diagram of the first half cycle in a working cycle of the CP circuit, and FIG. 2B is a working diagram of the second half cycle in a working cycle of the CP circuit.

[0041] Specifically, referring to FIG. 2A, the CP circuit opens the switch tubes QCH1, QCL1, QDH2 and QDL2 in the first half cycle to charge the capacitors Cfly1, Cfly2, Cout1 and Cout2, and the series voltage of Cfly1 and Cfly2 is VDD. Referring to FIG. 2B, the CP circuit opens the switch tubes QDH1, QDL1, QCH2 and QCL2 in the second half cycle to connect Cfly1, Cfly2, Cout1 and Cout2 in parallel, and the charge of Cfly1, Cfly2, Cout1 and Cout2 is redistributed, so that the voltage of the intermediate node Vout approaches 1 / 2VDD. After multiple cycles, the output voltage stabilizes at 1 / 2VDD, thereby realizing the half voltage function.

[0042] The CP circuit has the advantages of simple setting, high efficiency and is widely used. However, with the increase of charging power, the switch tube and the capacitor in the CP circuit will age over time, causing the device to be short-circuited or open-circuited, so that the voltage of the capacitor Cout1 and the capacitor Cout2 is increased, and the capacitor Cout1 and the capacitor Cout2 are directly connected in parallel with the battery. When the voltage of the battery exceeds the threshold value, there is a risk of fire and explosion. Therefore, the current CP charging technology cannot meet the reliability requirements of charging. In addition, with the increase of output current, the impedance of the cable line needs to be smaller, so that the diameter of the cable line becomes larger. Not only does it affect the user experience, but also the hardware cost is too high.

[0043] In addition to the above-mentioned CP charging technology, there are direct charging technology and Buck charging technology. Referring to FIGS. 3A and 3B, which are schematic diagrams of charging architecture, FIG. 3A is a schematic diagram of charging architecture for a single battery, and FIG. 3B is a schematic diagram of charging architecture for a double battery.

[0044] In summary, the charging circuit in the prior art has the problems of low charging reliability and high hardware cost. Moreover, due to the low charging reliability, it cannot achieve larger power charging.

[0045] Therefore, referring to FIG. 4, the embodiment of the present application provides a charging circuit. The charging circuit includes a resonant circuit 400, a transformer 500, and a plurality of charging branches 600. Each charging branch 600 includes a battery BAT to be charged. The transformer 500 includes a primary winding 501 and a plurality of secondary winding units 502. The plurality of secondary winding units 502 correspond to the plurality of charging branches 600 one by one. Each secondary winding unit 502 includes at least one secondary winding S. The input end of the resonant circuit 400 is connected with an external power supply, and the output end of the resonant circuit 400 is connected with the primary winding 501. Each secondary winding unit 502 is connected with the corresponding charging branch 600 to charge the battery BAT in the charging branch 600. It should be noted that two charging branches 600, two batteries BAT1 and BAT2, two secondary winding units 502, and each secondary winding unit 502 including one secondary winding S (the secondary windings in the two secondary winding units 502 are S1 and S2, respectively) are shown in FIG. 4.

[0046] The external power supply can be an adapter, a charger, etc., for providing a direct current signal. The input end of the resonant circuit 400 can receive the direct current signal provided by the external power supply, for converting the direct current signal into an alternating current signal.

[0047] The transformer 500 generates electromagnetic induction between the primary winding 501 and the plurality of secondary winding units 502 under the driving of the alternating current signal, so that the current is generated on each charging branch 600, thereby realizing charging for the battery BAT in each charging branch 600.

[0048] It can be understood that, due to the isolation by the transformer 500, the output voltage of the battery BAT is determined by the winding turns of the corresponding secondary winding. In a determined system, the winding turns of the transformer 500 are determined, and therefore, the ratio of the output voltages of the plurality of batteries BAT is equal to the ratio of the winding turns of the corresponding secondary windings. For example, in FIG. 4, the ratio of the output voltage Vo1 of the battery BAT1 to the output voltage Vo2 of the battery BAT2 is equal to the ratio of the secondary winding S1 to the secondary winding S2, i.e. Vo1 / Vo2=S1 / S2. Thus, the ratio of the output voltages of the plurality of batteries BAT can be changed by adjusting the winding turns ratio of the secondary windings S in the plurality of secondary winding units 502.

[0049] The charging circuit described above is also applicable to a series battery pack, i.e. the batteries BAT in the plurality of charging branches 600 are connected in series. Based on the charging circuit described above, the batteries BAT are charged in isolation and do not affect each other, which can avoid the problem that, in the conventional technology, when one battery in the series battery pack is fully charged, the other batteries in the series battery pack are no longer charged. Moreover, the flexibility of the charging circuit described above is relatively high, and only the secondary winding units 502 and the charging branches 600 need to be added to realize charging of multiple batteries.

[0050] In this embodiment, the charging circuit includes the resonant circuit 400, the transformer 500, and the plurality of charging branches 600. Each charging branch 600 includes a battery BAT to be charged. The transformer 500 includes the primary winding 501 and the plurality of secondary winding units 502. The plurality of secondary winding units 502 correspond to the plurality of charging branches 600 one by one, and each secondary winding unit 502 includes at least one secondary winding S. The input end of the resonant circuit 400 is connected to an external power supply, and the output end of the resonant circuit 400 is connected to the primary winding 501. Each secondary winding unit 502 is connected to the corresponding charging branch 600 to charge the battery BAT in the charging branch 600. Thus, due to the electromagnetic induction principle of the transformer 500, the primary winding 501 and the secondary winding S have extremely high insulation, i.e. high isolation, and therefore, the consequence of the breakdown of the switching tube causing the direct filling of the high output voltage into the battery BAT can be avoided, thereby the charging reliability of the charging circuit is relatively high. Further, since the charging circuit solves the problem of low charging reliability, the problem of being unable to realize larger power charging is solved.

[0051] In addition, by using the charging circuit, the voltage inputted by the external power supply to the charging circuit can be higher, and in the case that the charging power of the external power supply is constant, the current inputted to the charging circuit is smaller, so that the diameter of the cable line can be reduced, and the problem that the cost of the high-power charging hardware is also high can be solved.

[0052] In one of the embodiments, referring to the charging branch 600 shown in FIG. 5, the charging branch 600 further comprises a rectifier circuit 601 and a switch circuit 602; the input end of the rectifier circuit 601 is connected with the corresponding secondary winding unit 502, and the output end of the rectifier circuit 601 is connected with the battery BAT through the switch circuit 602.

[0053] The charging branch 600 further comprises a grounding capacitor Co, the first end of the grounding capacitor Co is connected with the output end of the rectifier circuit 601 and the switch circuit 602 respectively, and the second end of the grounding capacitor Co is grounded. The ground can be a signal ground SGND. The voltage of the Vo end in FIG. 5 can be measured to obtain the output voltage of the battery BAT.

[0054] In the embodiment, by setting the grounding capacitor Co, the noise interference of the voltage and the current in the circuit can be reduced, and the anti-interference ability of the circuit can be improved.

[0055] The rectifier circuit 601 is used to convert alternating current into direct current to charge the battery BAT, and by setting the parameters of the devices in the rectifier circuit 601, the direct current voltage and the direct current can be controlled and adjusted.

[0056] The switch circuit 602 can be a switch circuit composed of a switch tube, and can also be a switch circuit composed of a single-pole single-throw switch, which is used to control the opening and closing of the battery BAT connected with the switch circuit 602 to charge, and to realize flexible control of the battery charging BAT.

[0057] Optionally, the rectifier circuit 601 is a bridge rectifier circuit or a full-wave rectifier circuit.

[0058] In the case that the rectifier circuit 601 is a full-wave rectifier circuit, referring to the charging branch 600 shown in FIG. 6, the secondary winding unit 502 includes the second secondary winding S11 and the third secondary winding S22 connected in series, and the input end of the full-wave rectifier circuit is connected with the second secondary winding S11 and the third secondary winding S22. The full-wave rectifier circuit includes the first diode D1 and the second diode D2, the positive electrode of the first diode D1 is connected with the first end of the second secondary winding S11, the negative electrode of the first diode D1 is connected with the first end of the battery BAT, the positive electrode of the second diode D2 is connected with the first end of the third secondary winding S22, the negative electrode of the second diode D2 is connected with the first end of the battery BAT, the second end of the second secondary winding S11 is connected with the second end of the third secondary winding S22, and the second end of the second secondary winding S11 and the second end of the third secondary winding S22 are both connected with the second end of the battery BAT. The first end of the battery BAT and the second end of the battery BAT can be the positive electrode of the battery BAT and the negative electrode of the battery BAT respectively.

[0059] In the case that the rectifier circuit 601 is a bridge rectifier circuit, referring to the charging branch 600 shown in FIG. 7, the secondary winding unit 502 includes the first secondary winding S, and the input end of the bridge rectifier circuit is connected with the first secondary winding S. The bridge rectifier circuit includes the third diode D3, the fourth diode D4, the fifth diode D5 and the sixth diode D6, the positive electrode of the third diode D3 and the negative electrode of the sixth diode D6 are connected, and the positive electrode of the third diode D3 and the negative electrode of the sixth diode D6 are connected with the first end of the first secondary winding S; the negative electrode of the third diode D3 and the negative electrode of the fifth diode D5 are connected, and the negative electrode of the third diode D3 and the negative electrode of the fifth diode D5 are connected with the first end of the battery BAT; the negative electrode of the fourth diode D4 and the positive electrode of the fifth diode D5 are connected, and the negative electrode of the fourth diode D4 and the positive electrode of the fifth diode D5 are connected with the second end of the first secondary winding S; the positive electrode of the fourth diode D4 and the positive electrode of the sixth diode D6 are connected, and the positive electrode of the fourth diode D4 and the positive electrode of the sixth diode D6 are connected with the second end of the battery BAT. The first end of the battery BAT and the second end of the battery BAT can be the positive electrode of the battery BAT and the negative electrode of the battery BAT respectively.

[0060] In the embodiment, the bridge rectifier circuit is commonly used in the high-power charging circuit, and the full-wave rectifier circuit is commonly used in the low-power charging circuit, and a suitable rectifier circuit can be selected according to the requirement. In addition, the full-wave rectifier circuit has low cost, and the bridge rectifier circuit has high rectification efficiency.

[0061] In one of the embodiments, the switch circuit 602 comprises a first switch tube Q1; or, referring to the switch circuit 602 shown in FIG. 8, the switch circuit 602 comprises a second switch tube Q2 and a third switch tube Q3, the first pole of the second switch tube Q2 is connected with the output end of the rectifier circuit 601, the second pole of the second switch tube Q2 is connected with the first pole of the third switch tube Q3, and the second pole of the third switch tube Q3 is connected with the battery BAT.

[0062] The first switch tube Q1, the second switch tube Q2 and the third switch tube Q3 can be P-type MOS (Metal-Oxide-Semiconductor Field-Effect Transistor), N-type MOS, relay, MOS with diode in parallel, GaN (Gallium Nitride) field effect transistor or SiC (Silicon Carbide) field effect transistor, etc. In FIG. 8, the second switch tube Q2 and the third switch tube Q3 are both N-type MOS with diode in parallel as an example, the first pole of the second switch tube Q2 is the drain, the second pole of the second switch tube Q2 is the source, the first pole of the third switch tube Q3 is the source, and the second pole of the third switch tube Q3 is the drain; the gate of the second switch tube Q2 and the gate of the third switch tube Q3 are connected (marked with GS in the figure), and the gate of the second switch tube Q2 and the gate of the third switch tube Q3 are connected with the control circuit.

[0063] In the embodiments, the charging control of the battery BAT in each charging branch 600 can be realized by controlling the switch circuit 602 in each charging branch 600. In addition, the cost of using one switch tube is low, and the advantage of using two switch tubes is that the voltage stress of the switch tube can be reduced by reasonably controlling the turn-off of the two switch tubes.

[0064] In one of the embodiments, referring to the charging circuit shown in FIG. 9, the charging circuit further comprises a bridge circuit 700, and the input end of the resonant circuit 400 is connected with the external power supply through the bridge circuit 700.

[0065] The bridge circuit 700 is used to transform the power supply voltage into alternating current by periodically controlling the turn-off of the switch tube in the bridge circuit 700 and cooperating with the transformer 500.

[0066] Optionally, the bridge circuit 700 is a half-bridge circuit or a full-bridge circuit.

[0067] In the case that the bridge circuit 700 is a half-bridge circuit, referring to the bridge circuit 700 shown in FIG. 10, the bridge circuit comprises a fourth switch tube Q4, a fifth switch tube Q5, a first output capacitor Coss1, a second output capacitor Coss2 and a first ground capacitor Cin1. The first output capacitor Coss1 is connected between the first pole and the second pole of the fourth switch tube Q4, and the second output capacitor Coss2 is connected between the first pole and the second pole of the fifth switch tube Q5. The first pole of the fourth switch tube Q4 is connected with an external power supply (marked as Vin in the figure), the second pole of the fourth switch tube Q4 is connected with the first pole of the fifth switch tube Q5, and the second pole of the fifth switch tube Q5 is grounded. The first end of the first ground capacitor Cin is connected with the first pole of the fourth switch tube Q4, and the second end of the first ground capacitor Cin is grounded. The input end of the resonant circuit 400 is connected between the fourth switch tube Q4 and the fifth switch tube Q5, and the connection point is marked as SW. The output end of the resonant circuit 400 is connected with the first end of the primary winding 501, and the second end of the primary winding 501 is grounded.

[0068] In the case that the bridge circuit 700 is a full-bridge circuit, referring to the bridge circuit 700 shown in FIG. 11, the bridge circuit comprises a first bridge arm, a second bridge arm and a second ground capacitor Cin2, which are connected in parallel with each other and connected with an external power supply (marked as Vin in the figure) and grounded. The first bridge arm comprises a sixth switch tube Q6, a seventh switch tube Q7, a third output capacitor Coss3 and a fourth output capacitor Coss4, and the second bridge arm comprises an eighth switch tube Q8, a ninth switch tube Q9, a fifth output capacitor Coss5 and a sixth output capacitor Coss6. The third output capacitor Coss3, the fourth output capacitor Coss4, the fifth output capacitor Coss5 and the sixth output capacitor Coss6 are respectively connected between the first pole and the second pole of the sixth switch tube Q6, the seventh switch tube Q7, the eighth switch tube Q8 and the ninth switch tube Q9. The input end of the resonant circuit 400 is connected between the sixth switch tube Q6 and the seventh switch tube Q7, and the connection point is marked as SW1. The output end of the resonant circuit 400 is connected with the first end of the primary winding 501, and the second end of the primary winding 501 is connected between the eighth switch tube Q8 and the ninth switch tube Q9, and the connection point is marked as SW2.

[0069] The fourth switch Q4, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7, the eighth switch Q8 and the ninth switch Q9 can be P-type MOS, N-type MOS, relay, MOS with diode in parallel, GaN field effect transistor or SiC field effect transistor, etc. In FIG. 10 and FIG. 11, N-type MOS with diode in parallel is taken as an example, and the gates G4, G5, G6, G7, G8 and G9 of the fourth switch Q4, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7, the eighth switch Q8 and the ninth switch Q9 are connected with the control circuit.

[0070] In the embodiment, the full-bridge circuit is suitable for high-power conversion, and the half-bridge circuit is suitable for small and medium power conversion. In addition, the half-bridge circuit has low cost, and the full-bridge circuit has small power loss and high efficiency.

[0071] In one embodiment, referring to the resonant circuit 400 shown in FIG. 12, the resonant circuit 400 includes a resonant inductor Lr, a resonant capacitor Cr and an excitation inductor Lm connected in series, wherein a first end of the resonant inductor Lr is connected with the bridge circuit 700, a second end of the resonant inductor Lr is connected with a first end of the resonant capacitor Cr, a second end of the resonant capacitor Cr is connected with a first end of the primary winding 501, a first end of the excitation inductor Lm is connected between the second end of the resonant capacitor Cr and the first end of the primary winding 501, and a second end of the excitation inductor Lm is connected with a second end of the primary winding 501. The bridge circuit 700 can be the bridge circuit in FIG. 10 or FIG. 11, and the bridge circuit in FIG. 10 is taken as an example here.

[0072] The resonant circuit 400 and the transformer 500 constitute an LLC converter. It can be understood that the present application is not only suitable for LLC converter, but also suitable for CLLC, CLLLLC, DCX (direct current transformer) and other topological circuits.

[0073] In one embodiment, the charging circuit further includes a control circuit 800, referring to the control circuit 800 described in FIG. 13, the control circuit 800 is connected with the switching circuit 602, and is used to control the on-off of the switching circuit 602, or control the impedance of the switching circuit 602 to adjust the current passing through the switching circuit 602.

[0074] The control circuit 800 is also connected with the bridge circuit 700, and is used to control the on-off of the switch in the bridge circuit 700.

[0075] Specifically, the control circuit 800 includes a controller, which is connected with the GS end of the switching circuit 602 in FIG. 8, so as to control the on-off of the switching circuit 602 by controlling the size of the driving voltage output to the switching circuit 602, or control the impedance of the switching circuit 602 to adjust the current passing through the switching circuit 602.

[0076] The controller can also be connected to the G4 and G5 terminals of the bridge circuit 700 in FIG. 10, or the G6, G7, G8 and G9 terminals of the bridge circuit 700 in FIG. 11, to periodically control the on-off of the switching tubes in the bridge circuit 700. In FIG. 13, G4, G5, G6, G7, G8 and G9 are collectively represented as G.

[0077] In addition, the controller is also configured to receive the output voltage VBAT of the battery BAT detected by the output voltage detection circuit, receive the output current IBAT of the battery BAT detected by the output current detection circuit, receive the supply voltage Vin of the external power supply detected by the supply voltage detection circuit, and receive the supply current Iin of the external power supply detected by the supply current detection circuit.

[0078] In this embodiment, the control circuit 800 controls the impedance of the switching circuit 602 to adjust the current passing through the switching circuit 602, thereby achieving the control of the charging current of the battery BAT connected to the switching circuit 602, i.e. achieving the charging control of different batteries in the series battery pack.

[0079] The above embodiments of FIGS. 4-13 can be combined in any manner, for example, combining FIGS. 4, 6, 8, 11 and 12 to obtain the charging circuit shown in FIG. 14, or combining FIGS. 4, 5, 10 and 12 to obtain the charging circuit shown in FIG. 15. The meanings of the symbols in FIGS. 14 and 15 have been described in detail above and will not be repeated here.

[0080] It should be noted that the symbols in the plurality of secondary winding units 502 and the plurality of charging branches 600, since in the above only the symbols in any one secondary winding unit 502 and any one charging branch 600 are mentioned, in this FIG. 14 and FIG. 15, in order to distinguish the two secondary winding units 502 and the two charging branches 600, in FIG. 14, the two secondary windings in one of the secondary winding units 502 are denoted as S11 and S12, and the two secondary windings in the other secondary winding unit 502 are denoted as S21 and S22; the two switching tubes in the switching circuit 602 in one of the charging branches 600 are denoted as Q22 and Q23, and the two switching tubes in the switching circuit 602 in the other charging branch 600 are denoted as Q32 and Q33; the two diodes in the rectifier circuit 601 in one of the charging branches 600 are denoted as D11 and D12, and the two diodes in the rectifier circuit 601 in the other charging branch 600 are denoted as D21 and D22. In FIG. 15, one of the secondary windings in one of the secondary winding units 502 is denoted as S1, and one of the secondary windings in the other secondary winding unit 502 is denoted as S2. In FIG. 14 and FIG. 15, the ground capacitors in one of the charging branches 600 are denoted as Co1, and the ground capacitors in the other charging branch 600 are denoted as Co2, the ground symbol of Co1 is denoted as SGND1, and the ground symbol of Co2 is denoted as SGND2; the batteries in one of the charging branches 600 are denoted as BAT1, and the batteries in the other charging branch 600 are denoted as BAT2; the output voltage terminals in one of the charging branches 600 are denoted as Vo1, and the output voltage terminals in the other charging branch 600 are denoted as Vo2; the rectifier circuits in one of the charging branches 600 are denoted as 601A, and the rectifier circuits in the other charging branch 600 are denoted as 601B.

[0081] In one embodiment, when the batteries BAT in each charging branch 600 are connected in series, the ground terminals of each charging branch 600 are connected in series, that is, when the batteries BAT in the plurality of charging branches 600 are connected in series, for this application, only the output voltage terminals need to be connected in series, that is, the ground terminals in different charging branches 600 are connected in series with the output voltage nodes in other charging branches 600, to achieve charging of multiple batteries in series. For example, connecting the battery BAT1 and the battery BAT2 in FIG. 15 in series, and connecting SGND1 with Vo2, to obtain a multiple-battery series charging circuit as shown in FIG. 16.

[0082] Taking the double-battery system shown in FIG. 16 as an example, the ratio of the voltage of the primary winding 501 to the voltage of the secondary winding S1 in one of the secondary winding units 502 and the voltage of the secondary winding S2 in the other secondary winding unit 502 is 2:1:1, and the supply voltage Vin of the external power supply is 40V. Simulation is performed to obtain the voltage and current waveform diagram of the charging circuit shown in FIG. 17, wherein there are two curve diagrams in FIG. 17, and each curve diagram includes a plurality of curves changing with time. In the upper curve diagram, the sinusoidal curve represents the current on the primary winding 501, that is, the current ILr of the resonant inductor Lr; the triangular curve represents the current ILm of the magnetizing inductor Lm; and the straight line represents the output current Io1 of the battery BAT1 or the output current Io2 of the battery BAT2, Io1 = Io2 = 10A. In the lower curve diagram, the square wave represents the voltage VSW at the connection point SW; and the straight line represents the voltage at the output voltage terminal Vo1 or Vo2, Vo1 = Vo2 = 20V.

[0083] If some batteries in the series battery pack cannot be charged or do not need to be charged, and only some of the batteries need to be charged, the charging of the batteries with charging demand can be realized by controlling the on-off of the switch circuit 602 in the corresponding charging branch 600. For example, if the battery BAT1 in FIG. 16 does not need to be charged or cannot be charged, and only the battery BAT2 needs to be charged, the charging of only the battery BAT2 can be realized by controlling the switch circuit 602 corresponding to the battery BAT1 to be open and the switch circuit 602 corresponding to the battery BAT2 to be closed. At this time, the voltage and current waveform diagram of the charging circuit is shown in FIG. 18, wherein there are two curve diagrams in FIG. 18, and each curve diagram includes a plurality of curves changing with time. In the upper curve diagram, the sinusoidal curve represents the current on the primary winding 501, that is, the current ILr of the resonant inductor Lr; the triangular curve represents the current ILm of the magnetizing inductor Lm; the upper straight line represents the output current Io2 of the battery BAT2, and the lower straight line represents the output current Io1 of the battery BAT1. In the lower curve diagram, the square wave represents the voltage VSW at the connection point SW; the upper straight line represents the voltage at the output voltage terminal Vo2, and the lower straight line represents the voltage at the output voltage terminal Vo1.

[0084] In a multi-battery series system, battery balancing is an important circuit module, and the main function is to balance the voltages of the batteries, so as to ensure that the multi-battery series system can be normally charged and discharged. In the multi-battery series system, if one battery is in a full charge state and the other batteries are in a non-full charge state, the multi-battery series system cannot be charged at this time, because charging will cause the overcharging of the battery in the full charge state, and will cause danger. For example, when replacing one battery of a dual-battery series mobile phone, one battery may be in a full charge state and the other battery may be in a non-full charge state. Therefore, by using the charging circuit in the application, the charging mode for a specific battery can well solve this problem.

[0085] In addition, the charging circuit is combined with the existing balancing discharge circuit to form a charge and discharge circuit as shown in FIG. 19, wherein DCX is the part of the charging circuit except the battery BAT and the switching circuit 602, the right side of DCX is the switching circuit and the series-connected battery BAT1 and battery BAT2, BAT2 is a large battery, and BAT1 is a small battery. The discharge circuit includes a CP circuit connected to the positive electrode of the battery BAT1 and a MOS tube connected to the positive electrode of the battery BAT2, and the CP circuit is connected to the MOS tube to output the discharge voltage Vsys of the battery BAT1 and the battery BAT2.

[0086] In this case, where BAT2 is a large battery and BAT1 is a small battery, by combining the charging circuit of the application and controlling the on-off of the switching circuit corresponding to BAT2 and BAT1, reliable charging and balancing charge and discharge of the series-connected battery pack can be achieved.

[0087] In this embodiment, based on the above charging circuit, the batteries BAT are isolated from each other during charging, and do not affect each other, which can avoid the problem that in the conventional technology, when one battery in the series-connected battery pack is fully charged, the other batteries in the series-connected battery pack are no longer charged.

[0088] In one embodiment, the electronic device includes the charging circuit described in any of the above embodiments, and the electronic device can be a mobile phone, a mobile power supply, an electric vehicle, a notebook computer, a drone, a tablet computer, an electronic book, an electronic cigarette, a wearable device (such as a watch, a bracelet, smart glasses, etc.), a robot (such as a sweeping robot, a washing machine, etc.), a wireless earphone, a Bluetooth speaker, a wireless mouse, etc., and the embodiments of the application do not limit this.

[0089] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, and as long as the combinations of the technical features do not exist, they should be considered as the scope of the description.

[0090] The above embodiments only express several implementation ways of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A charging circuit, characterized by, The charging circuit comprises a resonant circuit, a transformer and a plurality of charging branches, each of the charging branches comprises a battery to be charged, the transformer comprises a primary winding and a plurality of secondary winding units, the plurality of secondary winding units correspond to the plurality of charging branches one by one, and each of the secondary winding units comprises at least one secondary winding; an input end of the resonant circuit is connected with an external power supply, and an output end of the resonant circuit is connected with the primary winding; each of the secondary winding units is connected with a corresponding charging branch to charge the battery in the charging branch.

2. The charging circuit of claim 1, wherein, The charging branch further comprises a rectifier circuit and a switching circuit; an input end of the rectifier circuit is connected with a corresponding secondary winding unit, and an output end of the rectifier circuit is connected with the battery through the switching circuit.

3. The charging circuit of claim 2, wherein, The rectifier circuit is a bridge rectifier circuit or a full-wave rectifier circuit.

4. The charging circuit of claim 3, wherein, In the case that the rectifier circuit is a bridge rectifier circuit, the secondary winding unit comprises a first secondary winding, and an input end of the bridge rectifier circuit is connected with the first secondary winding.

5. The charging circuit of claim 3, wherein, In the case that the rectifier circuit is a full-wave rectifier circuit, the secondary winding unit comprises a second secondary winding and a third secondary winding connected with each other in series, and an input end of the full-wave rectifier circuit is connected with the second secondary winding and the third secondary winding.

6. The charging circuit of claim 5, wherein, The full-wave rectifier circuit comprises a first diode and a second diode, a positive electrode of the first diode is connected with a first end of the second secondary winding, a negative electrode of the first diode is connected with a first end of the battery, a positive electrode of the second diode is connected with a first end of the third secondary winding, a negative electrode of the second diode is connected with the first end of the battery, a second end of the second secondary winding is connected with a second end of the third secondary winding, and the second end of the second secondary winding and the second end of the third secondary winding are both connected with a second end of the battery.

7. The charging circuit of claim 4, wherein, The bridge rectifier circuit comprises a third diode, a fourth diode, a fifth diode and a sixth diode, a positive electrode of the third diode and a negative electrode of the sixth diode are connected, and the positive electrode of the third diode and the negative electrode of the sixth diode are connected with a first end of the first secondary winding; a negative electrode of the third diode and a negative electrode of the fifth diode are connected, and the negative electrode of the third diode and the negative electrode of the fifth diode are connected with a first end of the battery; a negative electrode of the fourth diode and a positive electrode of the fifth diode are connected, and the negative electrode of the fourth diode and the positive electrode of the fifth diode are connected with a second end of the first secondary winding; a positive electrode of the fourth diode and a positive electrode of the sixth diode are connected, and the positive electrode of the fourth diode and the positive electrode of the sixth diode are connected with a second end of the battery.

8. The charging circuit of claim 2, wherein, The switching circuit comprises a first switch tube. Alternatively, the switching circuit comprises a second switch tube and a third switch tube, a first electrode of the second switch tube is connected with an output end of the rectifier circuit, a second electrode of the second switch tube is connected with a first electrode of the third switch tube, and a second electrode of the third switch tube is connected with the battery.

9. The charging circuit of claim 2, wherein, The charging circuit further comprises a control circuit connected with the switching circuit, for controlling the on-off of the switching circuit, or controlling the impedance of the switching circuit to adjust the current passing through the switching circuit.

10. The charging circuit of claim 2, wherein, The charging branch further comprises a grounding capacitor, a first end of the grounding capacitor being connected with the output end of the rectifier circuit and the switching circuit respectively, and a second end of the grounding capacitor being grounded.

11. The charging circuit of claim 9, wherein, The charging circuit further comprises a bridge circuit, an input end of the resonant circuit being connected with the external power supply through the bridge circuit.

12. The charging circuit of claim 11, wherein, The bridge circuit is a half-bridge circuit or a full-bridge circuit.

13. The charging circuit of claim 12, wherein, In the case that the bridge circuit is a half-bridge circuit, the bridge circuit comprises a fourth switch tube, a fifth switch tube, a first output capacitor, a second output capacitor and a first grounding capacitor; wherein the first output capacitor is connected between the first pole and the second pole of the fourth switch tube, the second output capacitor is connected between the first pole and the second pole of the fifth switch tube; the first pole of the fourth switch is connected with the external power supply, the second pole of the fourth switch tube is connected with the first pole of the fifth switch tube, and the second pole of the fifth switch tube is grounded; the first end of the first grounding capacitor is connected with the first pole of the fourth switch tube, and the second end of the first grounding capacitor is grounded; the input end of the resonant circuit is connected between the fourth switch tube and the fifth switch tube.

14. The charging circuit of claim 12, wherein, In the case that the bridge circuit is a full-bridge circuit, the bridge circuit comprises a first bridge arm, a second bridge arm and a second grounding capacitor, the first bridge arm, the second bridge arm and the second grounding capacitor are connected with each other in parallel, and are connected with the external power supply and grounded; the input end of the resonant circuit is connected with the first bridge arm.

15. The charging circuit of claim 14, wherein, The first bridge arm comprises a sixth switch tube, a seventh switch tube, a third output capacitor and a fourth output capacitor, the second bridge arm comprises an eighth switch tube, a ninth switch tube, a fifth output capacitor and a sixth output capacitor; wherein the third output capacitor, the fourth output capacitor, the fifth output capacitor and the sixth output capacitor are connected between the first pole and the second pole of the sixth switch tube, the first pole and the second pole of the seventh switch tube, the first pole and the second pole of the eighth switch tube and the first pole and the second pole of the ninth switch tube respectively; the input end of the resonant circuit is connected between the sixth switch tube and the seventh switch tube.

16. The charging circuit of claim 11, wherein, The resonant circuit comprises a resonant inductor, a resonant capacitor and an excitation inductor; a first end of the resonant inductor is connected with the bridge circuit, a second end of the resonant inductor is connected with a first end of the resonant capacitor, a second end of the resonant capacitor is connected with a first end of the primary winding, a first end of the excitation inductor is connected between the second end of the resonant capacitor and the first end of the primary winding, and a second end of the excitation inductor is connected with a second end of the primary winding.

17. The charging circuit of claim 11, wherein, The control circuit is further connected with the bridge circuit, for controlling the on-off of the switch tubes in the bridge circuit.

18. The charging circuit of claim 9, wherein, The control circuit comprises a controller, and the charging circuit further comprises an output voltage detection circuit, an output current detection circuit, a power supply voltage detection circuit and a power supply current detection circuit, all of which are connected with the controller; The controller is configured to receive the output voltage of the battery detected by the output voltage detection circuit; The controller is configured to receive the output current of the battery detected by the output current detection circuit; The controller is configured to receive the power supply voltage of the external power supply detected by the power supply voltage detection circuit; The controller is configured to receive the power supply current of the external power supply detected by the power supply current detection circuit.

19. The charging circuit according to any one of claims 1 to 18, wherein In the case where the batteries in each of the charging branches are connected in series with each other, the ground terminals of each of the charging branches are connected in series with each other.

20. An electronic device, comprising: The charging circuit as claimed in any one of claims 1 to 19.

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