Switching capacitor charging circuit

Abstract

The invention discloses a switched capacitor charging circuit which is configured to charge a first battery, the switched capacitor circuit comprises N-1 switched capacitor units which are sequentially coupled between a second port and a first port, and each switched capacitor unit comprises a flying capacitor; the first end of each first power tube is coupled to the first port, and the second end of each first power tube is coupled to one end of the different flying capacitor. When the switched capacitor circuit works in a first mode, the voltage conversion ratio of the switched capacitor circuit is N: 1, when the switched capacitor circuit works in a second mode, the voltage conversion ratio of the switched capacitor circuit is 2: 1, and when the switched capacitor circuit works in the second mode, at least one switched capacitor unit receives the voltage of the first voltage source through a first power tube coupled with the switched capacitor unit and generates the voltage of the first battery, therefore, the charging current and power of the switched capacitor charging circuit are improved, and the efficiency is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and more specifically, to a switched capacitor charging circuit. Background Art

[0002] With the widespread use of terminal devices such as mobile phones, tablets and Bluetooth headsets, higher requirements are placed on charging efficiency. Compared with traditional converter topologies, switched capacitor circuits (i.e. charge pumps) are widely used in mainstream fast charging solutions due to their ultra-high efficiency.

[0003] The current high-power single-battery fast charging solution consists of a switched capacitor converter with an input-output voltage ratio compatible with 4:1 and 2:1. When using a 4:1 switched capacitor converter solution, the topology can be changed to support the 2:1 mode at the same time. Figure 1 , is a schematic diagram of a switch capacitor charging circuit of the prior art. The switch capacitor charging circuit is composed of a 4:1 switch capacitor converter of a series-parallel topology. When the input-output voltage ratio is 4:1, the power tubes Q21, Q22, Q23, Q24, and the power tubes Q31, Q41, Q32, Q42, Q33, Q43 all participate in the work, and the flying capacitor C FIY1 、Flying capacitor C FIY2 、Flying capacitor C FIY3 Together they form a 4:1 switched capacitor converter; when the input-output voltage ratio is 2:1, the power tubes Q23, Q24, and the power tubes Q33, Q43 participate in the work, and the flying capacitor C FIY3 Together they form a 2:1 switched capacitor converter, and at this time the power tube Q32 remains in the on state. In this way, although the input-output voltage ratio can be switched between 4:1 and 2:1, when the input-output voltage ratio is 2:1, only the 2:1 switched capacitor converter consisting of the switch tube close to the high voltage side is used to work, which will make the efficiency of the switched capacitor charging circuit low. Summary of the invention

[0004] In view of this, the present invention provides a switched capacitor charging circuit to improve the efficiency when the input-output voltage ratio is 2:1.

[0005] The present invention provides a switched capacitor charging circuit, characterized by comprising:

[0006] The first port is configured to be coupled to a first voltage source;

[0007] A second port is configured to be coupled to a first terminal of a first battery, wherein a second terminal of the first battery is coupled to a ground terminal;

[0008] a switched capacitor circuit configured to charge the first battery, the switched capacitor circuit comprising N-1 switched capacitor units sequentially coupled between the second port and the first port, wherein each switched capacitor unit comprises a flying capacitor, the first switched capacitor unit is coupled to the second port, and the N-1th switched capacitor unit is coupled to the first port; and

[0009] At least one first power tube, each of which has a first end coupled to the first port and a second end coupled to one end of a different flying capacitor.

[0010] Preferably, the voltage conversion ratio of the switched capacitor circuit is N:1 when it works in the first mode, and is 2:1 when it works in the second mode, and in the second mode, at least one switched capacitor unit works, and N is a natural number greater than or equal to 3.

[0011] Preferably, in the second mode, at least one switched capacitor unit receives the voltage of the first voltage source through a first power tube coupled thereto, and generates the voltage of the first battery.

[0012] Preferably, in the second mode, at least one of the 1st to N-2nd switched capacitor units is coupled in parallel with the N-1th switched capacitor unit for operation, wherein at least one of the 1st to N-2nd switched capacitor units receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery.

[0013] Preferably, in the second mode, at least two of the 1st to N-2nd switched capacitor units are coupled in parallel to operate, wherein at least two of the 1st to N-2nd switched capacitor units receive the voltage of the first voltage source through the first power tube coupled thereto, and generate the voltage of the first battery.

[0014] Preferably, when the switched capacitor circuit operates in the first mode, all of the N-1 switched capacitor units participate in the operation.

[0015] Preferably, in the second mode, at least the first switched capacitor unit receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery to participate in the operation.

[0016] Preferably, the N-1 switch capacitor units switch working modes so that the flying capacitors are sequentially connected in series between the second port and the first port, or connected in parallel between the second port and the first port, so as to charge the first battery.

[0017] Preferably, each switched capacitor unit comprises:

[0018] A first structure comprising a third power tube, the flying capacitor and a fourth power tube coupled between the second port and the ground terminal; and

[0019] Two second power tubes are coupled to the first structure.

[0020] Preferably, in the second mode, in the first interval of each switching cycle, when any one of the switching capacitor units participates in the operation, the flying capacitor in the switching capacitor unit is coupled in series with the first battery between the first port and the ground terminal; in the second interval of each switching cycle, the flying capacitor in the switching capacitor unit is coupled in parallel with the first battery between the second port and the ground terminal.

[0021] Preferably, in the second mode, in the first interval of each switching cycle, when the i-th switching capacitor unit participates in the work, the first power tube coupled to the i-th switching capacitor unit is turned on, the second power tube coupled to both the i-th and i-1-th switching capacitor units is turned on, and the third power tube in the i-1-th switching capacitor unit is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the i-th switching capacitor unit are both turned on, where 2≤i≤N-2.

[0022] Preferably, in the second mode, in the first interval of each switching cycle, when the first switching capacitor unit participates in the work, the first power tube coupled to the first switching capacitor unit is turned on, and the second power tube coupled to the first switching capacitor unit and the second port is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the first switching capacitor unit are both turned on.

[0023] Preferably, in the second mode, in the first interval of each switching cycle, when the N-1th switching capacitor unit participates in the work, the two second power tubes in the N-1th switching capacitor unit are turned on, and the third power tube in the N-2th switching capacitor unit is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the N-1th switching capacitor unit are turned on.

[0024] Preferably, when the switched capacitor circuit operates in the first mode, the third power tube and the fourth power tube in each switched capacitor unit are controlled by a first control signal, and each second power tube is controlled by a second control signal, wherein the duty cycles of the first control signal and the second control signal are the same, and the phase difference is 180°.

[0025] Preferably, a switch tube is further provided between the first port and the switch capacitor circuit to prevent current from flowing back into the first voltage source.

[0026] The present invention aims to provide a switching capacitor charging circuit, which is configured to charge a first battery, and the switching capacitor circuit includes N-1 switching capacitor units sequentially coupled between the second port and the first port, wherein each switching capacitor unit includes a flying capacitor; and at least one first power tube, wherein the first end of each first power tube is coupled to the first port, and the second end is coupled to one end of a different flying capacitor. When the switching capacitor circuit works in the first mode, its voltage conversion ratio is N:1, and when it works in the second mode, its voltage conversion ratio is 2:1, and in the second mode, at least one switching capacitor unit receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery, so that the charging current and power of the switching capacitor charging circuit are improved, thereby making the efficiency higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 A schematic diagram of a switch capacitor charging circuit in the prior art;

[0029] Figure 2 is a schematic diagram of a switched capacitor charging circuit according to a first embodiment of the present invention;

[0030] FIG3( a ) is an equivalent circuit diagram of a switched capacitor charging circuit according to a first embodiment of the present invention in a first working stage under a first implementation mode;

[0031] FIG3( b ) is an equivalent circuit diagram of the switched capacitor charging circuit of the first embodiment of the present invention in the second working stage under the first implementation mode;

[0032] FIG4( a ) is an equivalent circuit diagram of the switched capacitor charging circuit of the first embodiment of the present invention in the first working stage under the second implementation mode;

[0033] FIG4( b ) is an equivalent circuit diagram of the switched capacitor charging circuit of the first embodiment of the present invention in the second working stage under the second implementation mode;

[0034] Figure 5 is a schematic diagram of a switched capacitor charging circuit according to a second embodiment of the present invention;

[0035] Figure 6 FIG. 4 is a schematic diagram of a switched capacitor charging circuit according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0037] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0038] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0039] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0040] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0041] Figure 2 FIG. 1 is a schematic diagram of a switched capacitor charging circuit according to a first embodiment of the present invention. Figure 2 As shown, the switched capacitor charging circuit of this embodiment includes a first port o1, a second port o2 and a switched capacitor circuit 1. The first port o1 is coupled to a first voltage source V BUS The second port o2 is coupled to the first end of the first battery B1, and the second end of the first battery B1 is coupled to the ground. In this embodiment, the switch capacitor circuit 1 is configured as a switch capacitor converter of a series-parallel architecture.

[0042] The switch capacitor circuit 1 includes N-1 switch capacitor units coupled in series and parallel between the second port o2 and the first port o1. The switch capacitor circuit 1 is configured to charge the first battery B1, and the N-1th switch capacitor unit is coupled to the first port o1, that is, close to the first voltage source V BUS On the high-voltage side, the first switched capacitor unit is close to the first voltage source V BUS The low-voltage side of the device has two power tubes coupled to the second port o2.

[0043] Furthermore, when the switched capacitor circuit 1 works in the first mode, its voltage conversion ratio is N:1, and when working in the second mode, its voltage conversion ratio is 2:1, and in the second mode, at least one switched capacitor unit participates in the work, and N is a natural number greater than or equal to 3.

[0044] Specifically, in this embodiment, N=4, the switched capacitor circuit 1 includes: 3 first structures 11~13 and 4 second power tubes Q21~Q24, the 3 first structures 11~13 are coupled in parallel between the second port o2 and the ground terminal, wherein each first structure includes at least two power tubes and a flying capacitor; the 4 second power tubes Q21~Q24 are respectively coupled between the second port o2 and the first first structure 11, between the first first structure 11 and the second first structure 12, between the second first structure 12 and the third first structure 13, and between the third first structure 13 and the first port o1.

[0045] Specifically, the first structure 11 includes a third power tube Q31, a flying capacitor C FIY1 and a fourth power tube Q41, which are sequentially coupled in series between the second port o2 and the ground terminal; the first structure 12 includes a third power tube Q32, a flying capacitor C FIY2 and a fourth power tube Q42, which are sequentially coupled in series between the second port o2 and the ground terminal; the first structure 13 includes a third power tube Q33, a flying capacitor C FIY3 The second power tube Q21 is coupled to the second port o2 and the flying capacitor C in the first structure 11. FIY1 and the common end of the fourth power tube Q41; the second power tube Q22 is coupled to the third power tube Q31 in the first structure 11 and the flying capacitor C FIY1 The common terminal and the flying capacitor C of the first structure 12 FIY2 and the common end of the fourth power tube Q42; the second power tube Q23 is coupled to the third power tube Q32 in the first structure 12 and the flying capacitor C FIY2 The common terminal and the flying capacitor C of the first structure 13 FIY3and the common end of the fourth power tube Q43; the second power tube Q24 is coupled to the third power tube Q33 of the first structure 13 and the flying capacitor C FIY3 between the common end and the first port o1.

[0046] Here, the i-th switching capacitor unit includes a first structure and two second power tubes connected to the first structure, and i is less than or equal to N-1. Specifically, in this embodiment, the first switching capacitor unit includes a first structure 11 and second power tubes Q21 and Q22; the second switching capacitor unit includes a first structure 12 and second power tubes Q22 and Q23; the third switching capacitor unit includes a first structure 13 and second power tubes Q23 and Q24.

[0047] Furthermore, the switched capacitor charging circuit further comprises at least one first power tube, wherein the first end of each first power tube is coupled to the first port o1, and the second end is coupled to one end of a different flying capacitor. The first power tube is configured such that, in the second mode, at least one switched capacitor unit receives the voltage V of the first voltage source through the first power tube coupled thereto. BUS , and generates the voltage of the first battery.

[0048] In the embodiment of the present invention, the switch capacitor charging circuit includes a first power tube Q1, a first end of which is coupled to the first port o1, and a second end of which is coupled to the flying capacitor C in the first switch capacitor unit. FIY1 At one end of the first power tube Q1, the first power tube Q1 is used to periodically turn on and off in the second mode, so that the first switch capacitor unit participates in the work, thereby improving the efficiency of the switch capacitor charging circuit.

[0049] Optionally, the switched capacitor charging circuit further includes a switch tube QB for preventing leakage to prevent current from flowing back into the first voltage source V BUS In this embodiment, the charging circuit further includes an input capacitor Cin to supply the first voltage source V BUS The output voltage is filtered.

[0050] In this embodiment, the switched capacitor circuit 1 is configured as a switched capacitor circuit with a series-parallel architecture, and the voltage conversion ratio between the input and output ends is 4:1. In other embodiments, the switched capacitor circuit 1 can be a switched capacitor circuit converter with other voltage conversion ratios (such as 3:1, 5:1, 6:1), and the present invention is not limited to this.

[0051] Specifically, when the switched capacitor circuit 1 operates in the first mode, that is, the voltage conversion ratio between the input voltage and the output voltage is 4:1, N-1 switched capacitor units all participate in the operation. In this embodiment, N=4, that is, 3 switched capacitor units all participate in the operation, so that the voltage VBAT on the first battery B1 is 1 / 4V.BUS More specifically, the N-1 switch capacitor units switch their working states so that all the flying capacitors are sequentially connected in series between the second port and the first port, or connected in parallel between the second port and the first port, so as to charge the first battery B1.

[0052] When the switched capacitor circuit operates in the first mode, the third power tube and the fourth power tube in each switched capacitor unit are controlled by a first control signal, and each second power tube is controlled by a second control signal, wherein the duty cycle of the first control signal and the second control signal are the same, and the phase difference is 180°.

[0053] Preferably, when the switched capacitor circuit 1 operates in the first mode, in the first interval of each switching cycle, the first control signal is at a high level, the second control signal is at a low level, the second power tubes Q21 to Q24 are turned on, the third power tubes Q31 to Q33 and the fourth power tubes Q41 to Q43 are turned off, and the flying capacitor C FIY1 ~C FIY3 and the first battery B1 in series, the first voltage source V BUS For flying capacitor C FIY1 ~C FIY3 and the first battery B1 is charged, so that the first voltage source V BUS Equal to three flying capacitors C FIY1 ~C FIY3 Voltage VC FIY1 ~VC FIY3 and the voltage VBAT on the first battery, that is: V BUS =VC FLY1 +VC FLY2 +VC FLY3 +VBAT; in the second interval of each switching cycle, the first control signal is low level, the second control signal is high level, the third power tube Q31~Q33 and the fourth power tube Q41~Q43 are all turned on, and the second power tube Q21~Q24 are all turned off. At this time, the flying capacitor C FIY1 ~C FIY3 are connected in parallel with the first battery B1, so that the three flying capacitors C FIY1 ~C FIY3 Voltage VC FIY1 ~VC FIY3 Equal to the voltage VBAT on the first battery, that is: VC FLY1 =VC FLY2 =VC FLY3 =VBAT. Therefore, it can be obtained that: the voltage VBAT of the first battery is equal to the first voltage source V BUS One quarter of that, that is, VBAT = 1 / 4V BUS .

[0054] When the switched capacitor circuit 1 works in the second mode, that is, the voltage conversion ratio of the input voltage to the output voltage is 2:1, the first switched capacitor unit participates in the work, or the N-1th switched capacitor unit is connected in parallel with the first switched capacitor unit and works together, that is, the third switched capacitor unit is connected in parallel with the first switched capacitor unit to work, so that the voltage VBAT on the first battery B1 is 1 / 2V. BUS The working process is described below in two implementation modes.

[0055] Fig. 3 is an equivalent circuit diagram of the switch capacitor charging circuit of the first embodiment of the present invention at different working stages under the first implementation mode of the second mode. The first implementation mode here means that when the switch capacitor circuit 1 works in the second mode, the third switch capacitor unit is connected in parallel with the first switch capacitor unit to work.

[0056] Referring to FIG. 3(a), in this embodiment, on the one hand, the third power tube in the N-2th switch capacitor unit remains in the on state, and the fourth power tube remains in the off state. Here, that is, the third power tube Q32 in the second switch capacitor unit remains in the on state, and the fourth power tube Q42 remains in the off state, so that the third switch capacitor unit is directly coupled to the first battery B1; on the other hand, the first power tube Q1, the first first structure 11, and the first second power tube Q21 constitute the first switch capacitor unit, so that the first switch capacitor unit is directly coupled to the first voltage source V BUS Therefore, the third switch capacitor unit forms a parallel structure with the first switch capacitor unit, and is connected in parallel between the first port o1 and the positive terminal of the first battery B1, that is, the second port o2.

[0057] Preferably, in the first interval of each switching cycle, the second power tubes Q21, Q23, and Q24 are turned on, the first power tube Q1 is turned on, and among the third power tubes Q31-Q33 and the fourth power tubes Q41-Q43, except for the third power tube Q32 which remains turned on, all other power tubes are turned off. At this time, the flying capacitor C FIY1 and the flying capacitor C FIY3 After being connected in parallel, it is then connected in series with the first battery B1, and the first voltage source V BUS For flying capacitor C FIY1 , C FIY3 and the first battery B1 is charged, so that the first voltage source V BUS Equal to the flying capacitor C FIY3 Voltage VC FIY3 and the voltage VBAT on the first battery, or the first voltage source V BUS Equal to the flying capacitor C FIY1 Voltage VC FIY1and the voltage V on the first battery BAT The sum of V BUS =VC FLY3 +V BAT , V BUS =VC FLY1 +V BAT ;

[0058] Referring to FIG. 3( b ), in the second interval of each switching cycle, among the third power tubes Q31 to Q33 and the fourth power tubes Q41 to Q43, except for the fourth power tube Q42 which remains off, all other power tubes are turned on, the first power tube Q1 and all the second power tubes Q21 to Q24 are turned off, and at this time, the flying capacitor C FIY1 , C FIY3 are connected in parallel with the first battery B1, so that the flying capacitor C FIY1 , C FIY3 Voltage VC FIY1 VC FIY3 and the voltage V on the first battery respectively BAT Equal, that is: VC FLY1 =VC FLY3 =V BAT . From this, we can get: the voltage V on the first battery B1 BAT Equal to the first voltage source V BUS One half of V BAT =1 / 2V BUS .

[0059] When the voltage conversion ratio of the input voltage and the output voltage of the switched capacitor charging circuit is 2:1 by adopting this implementation mode, when the parameters of the two switched capacitor units are exactly the same, especially under the premise that the on-resistance of each power tube is the same, since the two switched capacitor units are connected in parallel, on the one hand, under the condition that the output power of the system remains unchanged, the charging current flowing through each of the two switched capacitor units only needs half of the charging current when the original switched capacitor unit is working, and in the switched capacitor charging circuit, when the charging current exceeds a certain lower threshold value, the charging efficiency of the system is inversely correlated with the charging current, and the smaller the charging current, the higher the charging efficiency. Therefore, the switched capacitor charging circuit of this embodiment can improve the charging efficiency of the system in the second mode where the voltage conversion ratio of the input voltage and the output voltage is 2:1; on the other hand, if the charging current flowing through each of the two switched capacitor units remains unchanged, that is, equal to the charging current when the original switched capacitor unit is working, then by adopting this technical solution, the charging current of the load will be doubled, and the output power of the system can be doubled without considering other influences.

[0060] Fig. 4 is an equivalent circuit diagram of the switched capacitor charging circuit of the first embodiment of the present invention at different working stages in the second implementation mode of the second mode. The second implementation mode here means that when the switched capacitor circuit 1 works in the second mode, only the first switched capacitor unit participates in the work.

[0061] Referring to FIG. 4( a ), in this embodiment, the first power tube Q1, the first first structure 11, and the first second power tube Q21 constitute the first switch capacitor unit, so that the first switch capacitor unit is directly coupled to the first voltage source V BUS Therefore, the first switch capacitor unit is connected between the first port o1 and the positive terminal of the first battery B1, that is, the second port o2, and can work independently.

[0062] Preferably, in the first interval of each switching cycle, the second power tube Q21 is turned on, the first power tube Q1 is turned on, and all other power tubes are turned off. At this time, the flying capacitor C FIY1 and the first battery B1 are connected in series, the first voltage source V BUS For flying capacitor C FIY1 and the first battery B1 is charged, so that the first voltage source V BUS Equal to the flying capacitor C FIY1 Voltage VC FIY1 and the voltage on the first battery VBAT The sum of V BUS =VC FLY1 +V BAT ;

[0063] Referring to FIG4(b), in the second interval of each switching cycle, the third power tube Q31 and the fourth power tube Q41 are turned on, and the first power tube Q1 and all other power tubes are turned off. At this time, the flying capacitor C FIY1 and the first battery B1 in parallel, so that the flying capacitor C FIY1 Voltage VC FIY1 and the voltage V on the first battery BAT Equal, that is: V CFLY1 =V BAT . From this, we can get: the voltage V on the first battery B1 BAT Equal to the first voltage source V BUS One half of V BAT =1 / 2V BUS .

[0064] When the voltage conversion ratio between the input voltage and the output voltage of the switched capacitor charging circuit is 2:1 by adopting this implementation mode, since only the first switched capacitor unit close to the low voltage side is made to participate in the work, in the design of the switched capacitor charging circuit, in order to balance the area of ​​the chip, the on-resistance of the power tube close to the high voltage side is generally higher than the on-resistance of the power tube close to the low voltage side. For example, the on-resistance of the third power tube Q33 and the fourth power tube Q43 is higher than the on-resistance of the third power tube Q31 and the fourth power tube Q41. Therefore, the switching loss of the power tube in the first switched capacitor unit is lower than the switching loss of the power tube in the third switched capacitor unit. Therefore, when the on-resistance value of the first power tube Q1 is reasonable, the technical solution of this embodiment is adopted, which will improve the efficiency of the switched capacitor charging circuit.

[0065] Figure 5 Schematic diagram of a switched capacitor charging circuit of the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the switched capacitor circuit 1 is configured to be composed of N-1 switched capacitor units connected in series and parallel, and the voltage conversion ratio of the switched capacitor circuit 1 is N:1 when it works in the first mode, and 2:1 when it works in the second mode, and in the second mode, at least one switched capacitor unit participates in the work, and N is a natural number greater than or equal to 3.

[0066] Specifically, the switch capacitor circuit 1 includes N-1 switch capacitor units, specifically including N-1 first structures 11~1(N-1) and N second power tubes Q21~Q2N, the first structures 11~1(N-1) are coupled in parallel between the second port o2 and the ground terminal, wherein each first structure includes at least two power tubes and a flying capacitor; the N second power tubes Q21~Q2N are respectively used to couple the second port o2 and the first first structure 11, between two adjacent first structures in the first structure 11~1(N-1), and between the N-1 first structure 1(N-1) and the first port o1. In an embodiment of the present invention, the switch capacitor charging circuit includes a first power tube Q1, one end of the first power tube Q1 is coupled to the first port o1 through the switch tube QB, and the other end is coupled to the flying capacitor C in the first switch capacitor unit 11. FIY1 Coupled with the common node of the third power tube Q31. It should be understood that the first power tube Q1 can be connected to one end of any flying capacitor in the first to N-2th switching capacitor units, and in the second mode, the switching capacitor unit connected to the first power tube Q1 participates in the work.

[0067] Each first structure 1k includes a third power tube Q3k, a flying capacitor C FIYkand the fourth power tube Q4k are sequentially coupled in series between the second port o2 and the ground terminal; the first second power tube Q21 is coupled between the second port o2 and the flying capacitor C of the first first structure 11. FIY1 and the common end of the fourth power tube Q41; the i-th second power tube Q2i is used to couple the third power tube Q3(i-1) of the i-1th first structure 1(i-1) and the flying capacitor C FIY(i-1) The common terminal and the flying capacitor C of the i-th first structure 1i FIYi and the common end of the fourth power tube Q4i, wherein 2≤i≤N-1; the Nth second power tube Q2N is coupled to the third power tube Q3(N-1) of the N-1th first structure 1(N-1) and the flying capacitor C FIY(N-1) The kth switching capacitor unit includes the kth first structure 1k, the kth second power tube Q2k adjacent to the kth first structure 1k, and the k+1th second power tube Q2(k+1), where k is a positive integer, 1≤k≤N-1.

[0068] When the switched capacitor circuit 1 works in the first mode, that is, the voltage conversion ratio between the input voltage and the output voltage is N:1, N-1 switched capacitor units all participate in the work, so that the voltage V on the first battery B1 is BAT =1 / NV BUS .

[0069] When the switched capacitor circuit 1 operates in the second mode, that is, the voltage conversion ratio between the input voltage and the output voltage is 2:1, at least one switched capacitor unit receives the voltage V of the first voltage source through the first power tube coupled thereto. BUS , and generates the voltage of the first battery. In the embodiment of the present invention, only the first switch capacitor unit participates in the work, or the N-1th switch capacitor unit is connected in parallel with the first switch capacitor unit and participates in the work together, so that the voltage V on the first battery B1 is BAT =1 / 2V BUS .

[0070] When N is greater than or equal to 4, and the switch capacitor circuit 1 operates in the second mode where the voltage conversion ratio between the input voltage and the output voltage is 2:1, only the first switch capacitor unit may participate in the operation, or the N-1th switch capacitor unit may be connected in parallel with the first switch capacitor unit and participate in the operation together. When the first switch capacitor unit participates in the operation, the first power tube Q1, the first first structure 11, and the first second power tube Q21 constitute the first switch capacitor unit. When the N-1th switch capacitor unit is connected in parallel with the first switch capacitor unit and participates in the operation together, the third power tube Q3 (N-2) in the N-2th switch capacitor unit remains in the on state, and the fourth power tube Q4 (N-2) remains in the off state, so that the N-1th switch capacitor unit forms a parallel connection structure with the first switch capacitor unit.

[0071] It should be noted that when N is equal to 3, since there are only two switch capacitor units and the two switch capacitor units are not connected in parallel, when the switch capacitor circuit 1 works in the second mode, only the first switch capacitor unit participates in the work.

[0072] The rest of the second embodiment, such as the working status, working mode and control method, are similar to those of the first embodiment and will not be described in detail here.

[0073] It can be seen that the switched capacitor charging circuit of the present invention, by adding at least one first power tube, and three power tubes on the low-voltage side and a flying capacitor to form at least one group of 2:1 switched capacitor units, which are connected in parallel with a group of 2:1 switched capacitor units on the high-voltage side to work, so that when the voltage conversion ratio of the input voltage and the output voltage is 2:1 in the second mode, the charging current and power can be improved, and the efficiency can be made higher.

[0074] Figure 6 Schematic diagram of a switched capacitor charging circuit of the third embodiment of the present invention. The difference between this embodiment and the second embodiment is that when the switched capacitor circuit 2 works in the second mode, its voltage conversion ratio is 2:1, and in the second mode, it is not limited to the first switched capacitor unit to participate in the work, and N is a natural number greater than or equal to 3.

[0075] Specifically, the switch capacitor circuit 2 includes N-1 first structures 11~1(N-1) and N second power tubes Q21~Q2N, the first structures 11~1(N-1) are coupled in parallel between the second port o2 and the ground terminal, wherein each first structure includes at least two power tubes and a flying capacitor; the N second power tubes Q21~Q2N are respectively used to couple the second port o2 and the first first structure 11, between two adjacent first structures in the first structure 11~1(N-1), and between the N-1th first structure 1(N-1) and the first port o1.

[0076] N-1 first structures 11~1(N-1) and N second power tubes Q21~Q2N constitute N-1 switching capacitor units in sequence, each switching capacitor unit includes a first structure and two second power tubes coupled to the corresponding first structures, the first switching capacitor unit is coupled to the second port o2, and the N-1th switching capacitor unit is coupled to the first port o1.

[0077] In order to cooperate with the operation of the second mode, the switch capacitor circuit 2 also includes at least one first power tube, the first end of each first power tube is coupled to the first port o1, and the second end is coupled to one end of a different flying capacitor. And at least one switch capacitor unit receives the voltage V of the first voltage source through the first power tube coupled thereto. BUS , and generates the voltage of the first battery B1.

[0078] Preferably, in the second mode, in one implementation, at least one of the 1st to N-2nd switched capacitor units is coupled in parallel with the N-1st switched capacitor unit to operate, wherein at least one of the 1st to N-2nd switched capacitor units receives a voltage V of the first voltage source through a first power tube coupled thereto. BUS , and generates the voltage of the first battery. The N-1th switch capacitor unit receives the voltage VBUS of the first voltage source through the second power tube Q2N, and generates the voltage of the first battery.

[0079] In another embodiment, at least two of the first to N-2 switched capacitor units are coupled in parallel to operate, wherein at least two of the first to N-2 switched capacitor units receive a voltage V of a first voltage source through a first power tube coupled thereto. BUS , and generates the voltage of the first battery.

[0080] In another embodiment, at least one of the first to N-2 switched capacitor units operates, wherein at least one of the first to N-2 switched capacitor units receives a voltage V of a first voltage source through a first power tube coupled thereto. BUS , and generates the voltage of the first battery, and preferably the switching capacitor unit with a relatively small sequence number works to reduce the switching loss of the power tube.

[0081] In the second mode, in the first interval of each switching cycle, when any one of the switching capacitor units is involved in the operation, the flying capacitor in the switching capacitor unit is coupled in series with the first battery between the first port o1 and the ground terminal; in the second interval of each switching cycle, the flying capacitor in the switching capacitor unit is coupled in parallel with the first battery B1 between the second port o2 and the ground terminal.

[0082] Preferably, in the second mode, in the first interval of each switching cycle, when the i-th switching capacitor unit participates in the work, the first power tube coupled to the i-th switching capacitor unit is turned on, the second power tube coupled to both the i-th and i-1-th switching capacitor units is turned on, and the third power tube in the i-1-th switching capacitor unit is turned on; when the first switching capacitor unit participates in the work, the first power tube coupled to the first switching capacitor unit is turned on, and the second power tube coupled to both the first switching capacitor unit and the second port is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the first switching capacitor unit are turned on; when the N-1-th switching capacitor unit participates in the work, the two second power tubes in the N-1-th switching capacitor unit are turned on, and the third power tube in the N-2-th switching capacitor unit is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the N-1-th switching capacitor unit are turned on.

[0083] In the second interval of each switching cycle, the third and fourth power tubes in the i-th switching capacitor unit are both turned on, where 2≤i≤N-2.

[0084] In the embodiment of the present invention, the switch capacitor circuit 2 includes two first power tubes Q11 and Q13. One end of the first power tube Q11 is coupled to the first port o1 through the switch tube QB, and the other end is connected to the flying capacitor C in the first switch capacitor unit 11. FIY1 One end of the first power tube Q13 is coupled to the first port o1 through the switch tube QB, and the other end is coupled to the flying capacitor C in the third switch capacitor unit 13. FIY3 The common node of the third power tube Q33 is coupled. Thus, in the second mode, at least one of the first, third and N-1th switch capacitor units works to achieve a voltage conversion with a voltage conversion ratio of 2:1.

[0085] In the first implementation of the embodiment of the present invention, in the second mode, the first switch capacitor unit 11 is coupled in parallel with the N-1th switch capacitor unit to work, and the working process is the same as that of the second embodiment and will not be repeated here.

[0086] In the second implementation of the embodiment of the present invention, in the second mode, the third switch capacitor unit 13 is coupled in parallel with the N-1th switch capacitor unit to work. In the first interval of each switching cycle, the first power tube Q13 coupled to the third switch capacitor unit 13 is turned on, the second power tube Q23 coupled to the third and second switch capacitor units is turned on, and the third power tube Q32 in the second switch capacitor unit is turned on, so that the flying capacitor C in the switch capacitor unit 13 is turned on. FIY3 The first battery B1 is coupled in series between the first port o1 and the ground terminal; at the same time, the two second power tubes Q2N and Q2(N-1) in the N-1th switch capacitor unit 1(N-1) are turned on, and the third power tube Q3(N-2) in the N-2th switch capacitor unit 1(N-2) is turned on, so that the flying capacitor C in the switch capacitor unit 1(N-1) is turned on. FIY(N-1) is coupled in series with the first battery B1 between the first port o1 and the ground terminal; in the second interval of each switching cycle, the third and fourth power transistors in the third switching capacitor unit 13 and the N-1th switching capacitor unit 1 (N-1) are turned on, thereby switching the flying capacitor C in the switching capacitor unit 13 FIY3 The first battery B1 is connected in parallel between the second port o2 and the ground terminal, and the flying capacitor C in the switched capacitor unit 1 (N-1) is connected in parallel with the first battery B1. FIY(N-1) The first battery B1 is connected in parallel with the second port o2 and the ground terminal.

[0087] In the third implementation of the embodiment of the present invention, in the second mode, the first switch capacitor unit 11 is coupled in parallel with the third switch capacitor unit 13 to work. In the first interval of each switching cycle, the first power tube Q13 coupled to the third switch capacitor unit 13 is turned on, the second power tube Q23 coupled to both the third and second switch capacitor units is turned on, and the third power tube Q32 in the second switch capacitor unit is turned on, so that the flying capacitor C in the switch capacitor unit 13 is turned on. FIY3 The first battery B1 is coupled in series between the first port o1 and the ground terminal; at the same time, the first power tube Q11 coupled to the first switch capacitor unit 11 is turned on, and the second power tube Q21 coupled to the first switch capacitor unit 11 and the second port o2 is turned on, so that the flying capacitor C in the switch capacitor unit 11 is turned on. FIY1 The first battery B1 is coupled in series between the first port o1 and the ground terminal; in the second interval of each switching cycle, the third switching capacitor unit 13 and the third and fourth power transistors in the first switching capacitor unit 11 are turned on, so that the flying capacitor C in the switching capacitor unit 13 FIY3 The first battery B1 is connected in parallel to the second port o2 and the ground terminal, and the flying capacitor C in the switch capacitor unit 11 is connected to the ground terminal.FIY1 The first battery B1 is connected in parallel with the second port o2 and the ground terminal.

[0088] It can be seen that when the switched capacitor charging circuit of the embodiment of the present invention is in the second mode, at least one switched capacitor unit receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery, so that the charging current and power of the switched capacitor charging circuit are improved, thereby making the efficiency higher.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A switched capacitor charging circuit, characterized in that: include: The first port is configured to be coupled to a first voltage source; A second port is configured to be coupled to a first terminal of a first battery, wherein a second terminal of the first battery is coupled to a ground terminal; a switched capacitor circuit configured to charge the first battery, the switched capacitor circuit comprising N-1 switched capacitor units sequentially coupled between the second port and the first port, wherein each switched capacitor unit comprises a flying capacitor, the first switched capacitor unit is coupled to the second port, and the N-1th switched capacitor unit is coupled to the first port; as well as At least one first power tube, each of which has a first end coupled to the first port and a second end coupled to one end of a different flying capacitor.

2. The switched capacitor charging circuit according to claim 1, characterized in that: in, When the switch capacitor circuit works in the first mode, its voltage conversion ratio is N:1, and when working in the second mode, its voltage conversion ratio is 2:

1. In the second mode, at least one switch capacitor unit works, and N is a natural number greater than or equal to 3.

3. The switched capacitor charging circuit according to claim 2, characterized in that: In the second mode, at least one switched capacitor unit receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery.

4. The switched capacitor charging circuit according to claim 2, characterized in that: In the second mode, at least one of the 1st to N-2nd switched capacitor units is coupled in parallel with the N-1th switched capacitor unit to operate, wherein at least one of the 1st to N-2nd switched capacitor units receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery.

5. The switched capacitor charging circuit according to claim 2, characterized in that: In the second mode, at least two of the 1st to N-2nd switched capacitor units are coupled in parallel to operate, wherein at least two of the 1st to N-2nd switched capacitor units receive the voltage of the first voltage source through the first power tube coupled thereto and generate the voltage of the first battery.

6. The switched capacitor charging circuit according to claim 2, characterized in that: When the switched capacitor circuit operates in the first mode, the N-1 switched capacitor units all participate in the operation.

7. The switched capacitor charging circuit according to claim 2, characterized in that: In the second mode, at least the first switch capacitor unit receives the voltage of the first voltage source through the first power tube coupled thereto, and generates the voltage of the first battery to participate in the operation.

8. The switched capacitor charging circuit according to claim 1, characterized in that: The N-1 switch capacitor units switch working states so that the flying capacitors are sequentially connected in series between the second port and the first port, or connected in parallel between the second port and the first port, so as to charge the first battery.

9. The switched capacitor charging circuit according to claim 2, characterized in that: Each switched capacitor unit includes: A first structure comprising a third power tube, the flying capacitor and a fourth power tube coupled between the second port and the ground terminal; and Two second power tubes are coupled to the first structure.

10. The switched capacitor charging circuit according to claim 2, characterized in that: In the second mode, in the first interval of each switching cycle, when any one of the switching capacitor units participates in the operation, the flying capacitor in the switching capacitor unit is coupled in series with the first battery between the first port and the ground terminal; in the second interval of each switching cycle, the flying capacitor in the switching capacitor unit is coupled in parallel with the first battery between the second port and the ground terminal.

11. The switched capacitor charging circuit according to claim 9, characterized in that: In the second mode, in the first interval of each switching cycle, when the i-th switching capacitor unit participates in the work, the first power tube coupled to the i-th switching capacitor unit is turned on, the second power tube coupled to both the i-th and i-1-th switching capacitor units is turned on, and the third power tube in the i-1-th switching capacitor unit is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the i-th switching capacitor unit are both turned on, where 2≤i≤N-2.

12. The switched capacitor charging circuit according to claim 9, characterized in that: In the second mode, in the first interval of each switching cycle, when the first switching capacitor unit participates in the work, the first power tube coupled to the first switching capacitor unit is turned on, and the second power tube coupled to the first switching capacitor unit and the second port is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the first switching capacitor unit are both turned on.

13. The switched capacitor charging circuit according to claim 9, characterized in that: In the second mode, in the first interval of each switching cycle, when the N-1th switching capacitor unit participates in the work, the two second power tubes in the N-1th switching capacitor unit are turned on, and the third power tube in the N-2th switching capacitor unit is turned on; in the second interval of each switching cycle, the third and fourth power tubes in the N-1th switching capacitor unit are turned on.

14. The switched capacitor charging circuit according to claim 9, characterized in that: When the switched capacitor circuit operates in the first mode, the third power tube and the fourth power tube in each switched capacitor unit are controlled by a first control signal, and each second power tube is controlled by a second control signal, wherein the duty cycles of the first control signal and the second control signal are the same, and the phase difference is 180°.

15. The switched capacitor charging circuit according to claim 1, characterized in that: A switch tube is also arranged between the first port and the switch capacitor circuit to prevent current from flowing back into the first voltage source.

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