CN107846143B

CN107846143B - Capacitive power conversion circuit and charging control method

Info

Publication number: CN107846143B
Application number: CN201710173266.XA
Authority: CN
Inventors: 黄宗伟
Original assignee: Richtek Technology Corp
Current assignee: Richtek Technology Corp
Priority date: 2016-09-20
Filing date: 2017-03-22
Publication date: 2020-03-06
Anticipated expiration: 2037-03-22
Also published as: CN107846143A

Abstract

A capacitance type power supply conversion circuit is used for converting a direct current power supply on a confluence node into a charging power supply to charge a battery in a charging mode, and converting the battery voltage to generate a supply voltage on the confluence point in a power supply mode; the capacitive power conversion circuit includes: a transfer switch circuit comprising a plurality of transfer switches coupled to one or more transfer capacitors; and a transfer control circuit for generating a switch control signal to control the plurality of transfer switches; in a charging mode, the plurality of transfer switches control the coupling of the plurality of transfer capacitors such that the level of the charging current is substantially a default current gain multiple of the predetermined dc current level, and in a power supply mode, the plurality of transfer switches control the coupling of the plurality of transfer capacitors such that the level of the power supply voltage is substantially a default voltage gain multiple of the battery voltage level. The invention also provides a charging control method in the capacitive power conversion circuit.

Description

Capacitive power conversion circuit and charging control method

Technical Field

The present invention relates to a capacitive power conversion circuit, and more particularly, to a capacitive power conversion circuit capable of performing current multiplication or voltage multiplication in two directions. The invention also relates to a charging control method used in the capacitive power conversion circuit.

Background

Fig. 1 shows a charging circuit (charging circuit 1) of the prior art, which includes a power adapter (adaptor)11 with direct charging capability, which can provide charging current ICHG to charge a battery 50 with Constant Current (CC) via a cable 20 (e.g. USB cable) and a load switch 40(load switch), wherein the dc current IDC and the charging current ICHG are substantially equal. However, in the case of the prior art shown in fig. 1, where a standard cable such as a USB cable is used, the current limit of the cable is generally relatively low, for example about 5A or less, and the charging time is therefore longer. In order to increase the charging current (for example, 8A or more) by speeding up the charging time, a dedicated fast charging cable having a large wire diameter must be used, which is inconvenient for a user due to the use of a non-standard cable, and the fast charging cable has a large wire diameter and is not easy to flex.

Fig. 2A discloses another charging circuit (charging circuit 2) of the prior art, which includes a switching conversion circuit 60, which converts the power supply (such as but not limited to VBUS of 5V or 9V or 12V of USB PD) provided by the power adapter 11 into a charging current ICHG in the charging mode, and charges the battery 50 with a Constant Current (CC), in which the charging current ICHG may be larger than the dc current IDC. In The power supply mode, The prior art of fig. 2A can also support The USB OTG (On-The-Go) specification, please refer to fig. 2B, wherein The switching converting circuit 60 can reversibly convert The battery voltage VBAT into an output power conforming to The USB OTG specification (e.g. VBUS conforming to USB or USB PD) for supplying power to a load (not shown) conforming to The USB OTG specification. The prior art shown in fig. 2A and 2B has a disadvantage that, especially under the requirement of a relatively large constant charging current ICHG, it is difficult to select an inductor and a switch (not shown) with appropriate specifications to optimize various parameters such as charging current amount, current ripple amplitude, switch on resistance, energy conversion efficiency, etc., so that design optimization is not easy to achieve.

Compared with the prior art shown in fig. 1, the present invention has the advantages of providing multiplied charging current to charge the battery, shortening the charging time, using standard cables such as USB cables, operating at relatively low cable current, and facilitating the application of users, and compared with the prior art shown in fig. 2A and 2B, the present invention has the advantages of no need of inductors, reduced size, reduced cost, and easily optimized parts selection to achieve the best energy conversion efficiency.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of the prior art, and provides a capacitive power supply conversion circuit and a charging control method, which can provide multiplied charging current to charge a battery, can shorten the charging time, can use standard cables such as a USB cable and the like, can operate under relatively low cable current, and are convenient for a user to apply; in addition, the method has the advantages of no need of an inductor, size reduction, cost reduction, easy optimization of part selection to achieve the best energy conversion efficiency and the like.

In one aspect, the present invention provides a capacitive power conversion circuit for converting a dc power at a bus node into a charging power to charge a battery in a charging mode, wherein the charging power comprises a charging voltage and a charging current, the battery has a battery voltage, and the capacitive power conversion circuit is configured to convert the battery voltage into a supply voltage in a supply mode; wherein the DC power supply comprises a DC voltage and a DC current; the capacitive power conversion circuit includes: a transfer switch circuit comprising a plurality of transfer switches coupled to one or more transfer capacitors; and a transfer control circuit for generating a switch control signal to control the plurality of transfer switches; wherein in the charging mode, a power transmitting unit converts an input power to generate the dc power at the bus node, the power transmitting unit adjusts the dc current to a predetermined dc current level, and the switch control signal correspondingly operates the plurality of switches during a plurality of charging conversion periods to periodically couple the one or more conversion capacitors between a pair of one or more charging proportional voltage nodes, the bus node, and a ground node, such that the level of the charging current is substantially a predetermined current-increasing multiple (current-up factor) of the predetermined dc current level; wherein the charging power source is coupled to one of the one or more charging proportional voltage nodes; and in the power supply mode, the switch control signal correspondingly operates the plurality of transfer switches during a plurality of power supply transfer periods to cause the one or more transfer capacitors to be periodically and correspondingly coupled between a pair of one or more power supply proportional voltage nodes, the battery voltage, and the ground, to generate an output signal at one of the one or more power supply proportional voltage nodes, and to generate a power supply voltage at the bus node according to the output signal, such that the level of the power supply voltage is substantially a default boost multiple (voltage-up factor) of the battery voltage level.

In a preferred embodiment, the transfer capacitor comprises first and second transfer capacitors, and the plurality of power conversion periods comprises three power conversion periods; in the power supply mode, the switch control signal controls the plurality of transfer switches to periodically couple the first and second transfer capacitors between a pair of the plurality of power supply proportional voltage nodes, the battery voltage, and the ground in the three power supply transfer periods such that the voltage boost multiple is approximately 4/3, wherein in a steady state (steady), the voltage across the first and second transfer capacitors is approximately 2/3 and 1/3 of the battery voltage, respectively.

In a preferred embodiment, the transfer capacitor comprises first and second transfer capacitors, and the plurality of power conversion periods comprises two power conversion periods; in the power supply mode, the switch control signal controls the plurality of transfer switches to periodically couple the first and second transfer capacitors between a pair of the plurality of power supply proportional voltage nodes, the battery voltage, and the ground in the two power supply transfer periods, such that the voltage boost multiple is approximately 3/2, wherein in a steady state (steady), the voltage across the first and second transfer capacitors is approximately 1/2 of the battery voltage.

In a preferred embodiment, the transfer capacitor includes first and second transfer capacitors, and the plurality of charge transfer periods includes first and second charge transfer periods; wherein in the charging mode, the conversion control circuit controls the plurality of conversion switches to respectively switch and electrically connect the first end of the first conversion capacitor between the DC voltage and the charging voltage in the first charging conversion period and the second charging conversion period, respectively switch and electrically connect the second end of the first conversion capacitor between the charging voltage and the grounding point in the first charging conversion period and the second charging conversion period, respectively switch and electrically connect the first end of the second conversion capacitor between the DC voltage and the charging voltage in the second charging conversion period and the first charging conversion period, respectively switch and electrically connect the second end of the second conversion capacitor between the charging voltage and the grounding point in the second charging conversion period and the first charging conversion period, so that the level of the charging current is approximately 2 times the predetermined DC current level.

In a preferred embodiment, the capacitive power conversion circuit further comprises a linear adjustment switch circuit for converting the output signal to generate the supply voltage at the bus node in the power supply mode, wherein the conversion control circuit further generates a linear adjustment signal for linearly controlling an adjustment switch of the linear adjustment switch circuit such that the level of the supply voltage is adjusted to a default output voltage level; and in the charging mode, the regulating switch is controlled to be in a conducting state.

In a preferred embodiment, in the power supply mode, the conversion control circuit further determines the default boost multiple according to a battery voltage related signal, so that the output signal is close to but greater than the power supply voltage, and the voltage across the input terminal and the output terminal of the regulating switch is less than a default drop voltage (droop voltage).

In a preferred embodiment, The input power supply conforms to The Universal Serial bus specification or Universal Serial bus Power supply specification (USB or USB PD), and The supply voltage conforms to The Universal Serial bus On-The-Go specification (USB OTG).

To achieve the above object, in another aspect, the present invention provides a power conversion control method, including: in a charging mode, a capacitor type power supply conversion circuit is used for converting a direct current power supply on a bus node into a charging power supply to charge a battery, wherein the charging power supply comprises a charging voltage and a charging current, and the battery has a battery voltage; and under a power supply mode, converting the battery voltage into a power supply voltage by the capacitive power conversion circuit; wherein a power transmitting unit converts an input power to generate the DC power at the sink node, the DC power including a DC voltage and a DC current; wherein the capacitive power conversion circuit comprises a transfer switch circuit comprising a plurality of transfer switches coupled to one or more transfer capacitors; wherein in the charging mode, the step of converting the dc power into the charging power comprises: adjusting the DC current to a predetermined DC current level; during a plurality of charging conversion periods, correspondingly operating the plurality of conversion switches to periodically and correspondingly couple the one or more conversion capacitors between a pair of one or more charging proportional voltage nodes, the dc voltage, and a ground point, such that the level of the charging current is substantially a default current-increase multiple (current scale-up factor) of the predetermined dc current level; and coupling the charging power source to one of the one or more charging proportional voltage nodes; wherein in the power supply mode, the step of converting the battery voltage into the power supply voltage comprises: during a plurality of power conversion periods, correspondingly operating the plurality of conversion switches to periodically and correspondingly couple the one or more conversion capacitors between a pair of one or more power proportional voltage nodes, the battery voltage and the grounding point to generate an output signal at one of the one or more power proportional voltage nodes; and generating the supply voltage on the bus node according to the output signal such that the level of the supply voltage is substantially a default voltage scale-up factor of the battery voltage level.

In a preferred embodiment, the transfer capacitor comprises first and second transfer capacitors, and the plurality of power conversion periods comprises three power conversion periods; wherein in the power supply mode, the step of converting the battery voltage into the power supply voltage comprises: in the three power conversion periods, the first and second conversion capacitors are periodically coupled between a pair of the power proportional voltage nodes, the battery voltage, and the ground, such that the voltage boost multiple is approximately 4/3, wherein in a steady state (steady), the voltage across the first and second conversion capacitors is approximately 2/3 and 1/3, respectively.

In a preferred embodiment, the transfer capacitor comprises first and second transfer capacitors, and the plurality of power conversion periods comprises two power conversion periods; wherein in the power supply mode, the step of converting the battery voltage into the power supply voltage comprises: in the two power conversion periods, the first and second conversion capacitors are periodically coupled between a pair of the power proportional voltage nodes, the battery voltage, and the ground point, such that the voltage boost multiple is approximately 3/2, wherein in a steady state (steady), the voltage across the first and second conversion capacitors is approximately 1/2 of the battery voltage.

In a preferred embodiment, the power conversion control method further includes: in the power supply mode, a regulation switch of a linear regulation switch circuit is linearly controlled to convert the output signal to generate the power supply voltage on the bus node, wherein the level of the power supply voltage is regulated to a default output voltage level; and controlling the regulating switch to be in a conducting state in the charging mode.

In a preferred embodiment, in the power supply mode, the default boost multiple is further determined according to a battery voltage related signal, so that the output signal is close to but greater than the power supply voltage, and the voltage across the input terminal and the output terminal of the regulating switch is smaller than a default drop voltage (droop voltage).

The purpose, technical content, features and effects of the present invention will be more readily understood through the following detailed description of specific embodiments.

Drawings

FIG. 1 shows a schematic diagram of a prior art charging circuit;

FIGS. 2A and 2B show schematic diagrams of a prior art charging circuit;

FIG. 3 is a schematic diagram of a capacitive power conversion circuit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a capacitive power conversion circuit according to an embodiment of the present invention;

FIGS. 5A and 5B are schematic diagrams illustrating a capacitive power conversion circuit according to an embodiment of the invention;

FIG. 6 is a schematic diagram of a capacitive power conversion circuit according to an embodiment of the present invention;

fig. 7A and 7B are schematic equivalent circuits of the capacitive power conversion circuit according to the present invention.

Detailed Description

Referring to fig. 3, a schematic diagram of a capacitive power conversion circuit (capacitive power conversion circuit 30) according to an embodiment of the present invention is shown, wherein the capacitive power conversion circuit 30 is used for converting a dc power on a bus node BN into a charging power to charge a battery 50 in a charging mode, wherein the charging power includes a charging voltage VCHG and a charging current ICHG, the battery has a battery voltage VBAT, and wherein the dc power includes a dc voltage VDC and a dc current IDC; the capacitive power conversion circuit 30 includes: a transfer switch circuit 31 including a plurality of transfer switches (not shown) coupled to a transfer capacitor (e.g., C1 in fig. 3) or a plurality of transfer capacitors (e.g., C1-CN in fig. 3, where N is a natural number); and a switching control circuit 32 for generating a switch control signal CTRL to control the switches. As shown, a power transmitting unit 10 converts an input power to generate the dc power at the bus node BN, and the power transmitting unit 10 may be, for example, a power adapter to convert an ac input power into the dc power, or may be a dc-dc converting circuit to convert an input power from, for example, a mobile power (power bank) into the dc power; in one embodiment, the power transmitting unit 10 may support a constant current direct charging mode, and directly charge the battery 50 without control of the capacitive power conversion circuit 30 (related lines are not shown). In the charging mode, the power transmitting unit 10 adjusts the dc current IDC to a predetermined dc current level, and the switch control signal CTRL correspondingly operates the plurality of switches during a plurality of charging conversion periods, so that the one or more conversion capacitors (C1 or C1-CN) are periodically and correspondingly coupled between a pair of one or more charging proportional voltage nodes (e.g., ND1 or ND1-NDM in fig. 3, where M is a natural number), the bus node BN, and a ground node, such that the level of the charging current ICHG is substantially a predetermined current-increasing multiple (currentscale-up factor) K of the predetermined dc current level of the dc current IDC, in a preferred embodiment, K is greater than 1, that is, the charging current ICHG is greater than the dc current IDC, so that the real capacitive power conversion circuit of the present invention can be used with a constant dc current, the battery 50 is charged with a relatively large charging current ICHG, shortening the charging time; wherein the charging power source is coupled to a node (e.g., corresponding to ND1 in fig. 3) of the one or more charging proportional voltage nodes, and the charging current ICHG is generated via the node. In an embodiment, the capacitive power conversion circuit 30 may include, for example, but not limited to, a divide charge pump (divider charge pump).

It should be noted that: since the parasitic effect of the circuit components or the matching between the components is not necessarily ideal, although the level of the charging current ICHG is about a default current increasing multiple K of the predetermined dc current level, the level of the charging current ICHG actually generated may not be exactly K times of the predetermined dc current level, but only close to K times, i.e., "about" is a default current increasing multiple K of the predetermined dc current level, and the other references to "about" are also the same herein. It should be noted that in the embodiment having a plurality of charge-proportional voltage nodes, the current increase multiple K varies with the node to which the charging power source is coupled; in the embodiment with only one charge ratio voltage node, the current increase multiple K is 2, i.e. the level of the charging current ICHG is substantially 2 times the predetermined dc current level, but in other embodiments, K is not limited to an integer.

It should be noted that the power transmitting unit 10 is not limited to adjust the dc current IDC to the predetermined dc current level, and in an embodiment, the power transmitting unit 10 may also adjust the dc voltage VDC to a predetermined dc voltage level, in which case, the capacitive power converting circuit 30 may still make the level of the charging voltage VCHG substantially equal to a predetermined voltage proportion multiple K 'of the predetermined dc voltage level according to the above operations, and in a preferred embodiment, K' is less than 1, so as to achieve the capacitive buck power converting mode.

With continued reference to fig. 3, in an embodiment, the power transmitting unit 10 is further coupled to a capacitive power conversion circuit (e.g. the capacitive power conversion circuit 30) through a cable 20 and/or a connector (not shown), wherein the cable 20 or the connector may be, for example, but not limited to, a cable or a connector conforming to the universal serial bus power supply specification (USB PD) or the universal serial bus specification (USB), and includes a power line 21 and a signal line 22, wherein the power line 21 is used for transmitting a dc power. It should be noted that the cable 20 or the connector may be omitted in other embodiments.

Referring to fig. 3, in an embodiment, the switching control circuit 32 detects the dc current IDC to generate a current-related signal (for example, ISEN shown in the figure), and the power transmitting unit 10 adjusts the dc current IDC to the predetermined dc current level according to the current-related signal ISEN. In a preferred embodiment, the switching control circuit 32 transmits the current-related signal ISEN to the power transmitting unit 10 through the signal line 22.

In many applications, The charging circuit described above needs to support The USB On-The-Go specification, i.e., in a power mode, The battery voltage is converted into a power supply voltage, and The power supply voltage is outputted through, for example, The bus node to be used by The load conforming to The USB OTG specification. Referring to fig. 4, in one embodiment, the charging circuit 4 further includes a switching converting circuit 60 (generally, a switching boost circuit) for converting the battery voltage VBAT to generate a supply voltage VOUT at the bus node BN for supplying power to a USB OTG load 70 (e.g., a flash memory card conforming to USB OTG specification) in the power supply mode.

In one embodiment, the capacitive power conversion circuit of the present invention can also be used to convert the battery voltage VBAT into a supply voltage VOUT in a power supply mode without an additional conversion circuit (e.g., the switching conversion circuit 60 in the embodiment of fig. 4). Referring to fig. 5A, in an embodiment, in the capacitive power conversion circuit (the capacitive power conversion circuit 30A including the capacitive power conversion circuit 30 shown in fig. 3), the plurality of switches may be correspondingly operated by the switch control signal CTRL during a plurality of power conversion periods in the power mode, such that the one or more conversion capacitors (C1 or C1-CN) are periodically and correspondingly coupled between one or more power proportional voltage nodes (e.g., corresponding to NS1 or NS1-NSQ shown in fig. 5A, where Q is a natural number), the battery voltage VBAT, and the ground node, to generate an output signal VPO at one node (e.g., NSQ shown in fig. 5A) of the one or more power proportional voltage nodes (NS1 or NS1-NSQ), and generate a power voltage VOUT at the bus node BN according to the output signal VPO, so that the level of the supply voltage VOUT is substantially a predetermined boost-up factor J of the level of the battery voltage VBAT.

Referring to fig. 5B, in order to make the level of the supply voltage VOUT closer to the USB OTG specification (for example, but not limited to 5V), in an embodiment, the capacitive power conversion circuit (for example, the capacitive power conversion circuit 30B in the figure) of the present invention may further include a linear regulating switch circuit 33 for converting the output signal VPO into the supply voltage VOUT, wherein the conversion control circuit 32 further generates a linear regulating signal CTRS according to the supply voltage VOUT for linearly controlling a regulating switch SWG of the linear regulating switch circuit 33, so that the level of the supply voltage VOUT is regulated to a default output voltage level (for example, 5V).

It should be noted that, in the case of having the linear adjustment switch circuit, in an embodiment, in the charging mode, the adjustment switch (e.g., SWG) can be controlled to be turned on, so that the capacitive power conversion circuit can be charged in a current multiplication manner as described above.

It is noted that, the capacitive power conversion circuit (e.g., 30A, 30B) of the present invention performs power conversion in a capacitive power conversion manner to charge the battery or supply the usb otg load no matter in the charging mode or the power supply mode, so that an inductor of a switching power conversion circuit (such as, but not limited to, a switching buck, boost, or buck-boost power conversion circuit) is not required, thereby saving cost and space. In addition, the capacitive power conversion circuit of the present invention can further share a conversion capacitor (e.g., one or more of the conversion capacitors C1 or C1-CN) and a plurality of conversion switches, thereby further saving cost and space.

Referring to fig. 6, a schematic diagram of a capacitive power conversion circuit (capacitive power conversion circuit 30C) according to an embodiment of the present invention is shown, in which the conversion capacitor includes first and second conversion capacitors C1 and C2, and the plurality of charge conversion periods include first and second charge conversion periods; wherein in the charging mode, the switching control circuit 32 controls a plurality of switches (e.g. switches SW1-SW11 shown in the figure) to switch the first terminal of the first switching capacitor C1 between the DC voltage VDC and the charging voltage VCHG in the first charging switching period and the second charging switching period, respectively, to switch the second terminal of the first switching capacitor C1 between the charging voltage VCHG and the ground point in the first charging switching period and the second charging switching period, respectively, to switch the first terminal of the second switching capacitor C2 between the DC voltage VDC and the charging voltage VCHG in the second charging switching period and the first charging switching period, respectively, to switch the second terminal of the second switching capacitor C2 between the charging voltage VCHG and the ground point in the second charging switching period and the first charging switching period, respectively, so that the level of the charging current ICHG is approximately 2 times the predetermined dc current level. In this embodiment, the switching between the node pairs of C1 and C2 is in opposite phase.

Referring to fig. 6 and fig. 7A, fig. 7A shows an equivalent circuit schematic diagram of the capacitive power conversion circuit in different power conversion periods when the boost multiple J is 3/2 times in the power supply mode, in the present embodiment, in the power supply mode, the power conversion periods include two power conversion periods (e.g., the power conversion periods TP1 and TP2 in fig. 7A); the conversion control circuit 32 controls the plurality of conversion switches (e.g., the conversion switches SW1-SW11 shown in the figure) by the switch control signal CTRL to periodically couple the first and second conversion capacitors between a pair of the power supply proportional voltage nodes (e.g., NS1 and NS2 in fig. 7A), the battery voltage VBAT, and the ground point in the power supply conversion periods TP1 and TP2, so that the voltage boosting multiple is substantially 3/2, wherein in a steady state (steady), the voltage across the first and second conversion capacitors is substantially 1/2 of the battery voltage.

Referring to fig. 7A, in detail, in the present embodiment, in the power conversion period TP1, the first and second conversion capacitors C1 and C2 are coupled between the battery voltage VBAT and the ground by switching the plurality of conversion switches to be connected in series, and in the power conversion period TP2, the first and second conversion capacitors C1 and C2 are coupled in parallel between the power proportional voltage node NS2 and the battery voltage VBAT by switching the plurality of conversion switches, wherein the capacitive power conversion circuit generates the output signal VPO through the power proportional voltage node NS 2; the above-mentioned cycle is repeated, so that the boost ratio is about 3/2 in the steady state, and the voltage across the first and second conversion capacitors C1 and C2 is about 1/2 of the battery voltage VBAT.

Referring to fig. 6 and fig. 7B, fig. 7B shows an equivalent circuit diagram of the capacitive power conversion circuit in different power conversion periods when the boost multiple J is 4/3 times, in the present embodiment, in the power mode, the power conversion periods include three power conversion periods (e.g., the power conversion periods TP1, TP2, and TP3 in fig. 7B); the conversion control circuit 32 controls the plurality of conversion switches (e.g., the conversion switches SW1-SW11 shown in the figure) by the switch control signal CTRL, so that the first and second conversion capacitors are periodically coupled between a pair of the power supply proportional voltage nodes (e.g., NS1, NS2, and NS3 in fig. 7B), the battery voltage VBAT, and the ground point in the power supply conversion periods TP1, TP2, and TP3, respectively, such that the voltage boosting multiple is substantially 4/3, wherein in a steady state (steady state), the voltage across the first and second conversion capacitors is substantially 2/3 and 1/3 of the battery voltage, respectively.

Referring to fig. 7B, in detail, in the present embodiment, during the power conversion period TP1, the first and second conversion capacitors C1 and C2 are coupled between the battery voltage VBAT and the ground point by switching the plurality of conversion switches to be connected in series, and during the power conversion period TP2, the second transfer capacitor C2 is coupled between the supply proportional voltage node NS2 and the battery voltage VBAT through the switching of a plurality of transfer switches, in the power conversion period TP3, the first and second conversion capacitors C1 and C2 are connected in series and coupled between the power proportional voltage node NS2 and the battery voltage VBAT by the switching of the plurality of conversion switches, wherein the capacitive power conversion circuit generates an output signal VPO via a supply proportional voltage node NS2, wherein the polarity of the second conversion capacitor C2 in the power conversion period TP3 is opposite to the polarity in the other power conversion periods TP1 and TP 2; such cycles are repeated, so that the boost ratio is about 4/3 in the steady state, and the voltage across the first and second conversion capacitors C1 and C2 is about 2/3 and 1/3 of the battery voltage VBAT, respectively.

It should be noted that the sequence between the power supply conversion periods and the voltage division relationship between the conversion capacitors in the two embodiments are only examples and are not limited.

Referring to fig. 5A, 5B and 6, in an embodiment, the capacitive power conversion circuit (such as the capacitive

power conversion circuits

30A, 30B and 30C) of the present invention can determine a required boost multiple J (for example, one of the above 3/2 times or 4/3 times is selected) according to a signal related to the battery voltage VBAT and a target value of the power supply voltage VOUT, and adaptively adjust the coupling manner of the plurality of transfer switches and the plurality of power supply conversion periods according to the required boost multiple J to achieve the required boost multiple J; with continued reference to fig. 5B and 6, in a preferred embodiment, the required boost multiple J enables the output signal VPO to approach but be greater than the supply voltage VOUT, such that the voltage across the input and output terminals of the regulation switch (i.e., VPO-VOUT) is less than a predetermined drop voltage (droop voltage) to improve the conversion efficiency.

In an embodiment, the USB OTG load circuit (e.g., the load 70 in fig. 4, 5A, 5B and 6) and the capacitive power conversion circuit (e.g., the capacitive

power conversion circuits

30, 30A, 30B and 30C in fig. 4, 5A, 5B and 6) are connected to each other by the USB PD or USB connector (not shown).

The present invention has been described in terms of the preferred embodiments, and the above description is only for the purpose of making the content of the present invention easy to understand for those skilled in the art, and is not intended to limit the scope of the present invention. The various embodiments described are not limited to single use, but may be used in combination; for example, the aforementioned voltage boosting multiples 4/3 and 3/2 can be used together, so that the capacitive power conversion circuit of the present invention can have these two voltage boosting multiples, which can be determined according to the battery voltage and the power supply voltage. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent variations and various combinations, for example, the capacitive power conversion circuit of the present invention can be used in parallel to reduce the equivalent resistance of the conversion circuit and improve the conversion efficiency. For another example, the converting capacitor may further include a third converting capacitor, and the plurality of power conversion periods includes three power conversion periods; in the power supply mode, the switch control signal controls the plurality of transfer switches to periodically couple the first, second, and third transfer capacitors to one of the pair of power supply proportional voltage nodes, the battery voltage, and the ground point during the three power supply transfer periods, such that the voltage boosting multiple is substantially 7/4. For example, the term "performing processing or operation or generating an output result according to a signal" in the present invention is not limited to the signal itself, and includes performing voltage-to-current conversion, current-to-voltage conversion, and/or ratio conversion on the signal, and then performing processing or operation according to the converted signal to generate an output result, if necessary. It is understood that those skilled in the art can devise various equivalent variations and combinations, not necessarily all illustrated, without departing from the spirit of the invention. Accordingly, the scope of the present invention should be determined to encompass all such equivalent variations as described above.

Claims

1. A capacitance type power conversion circuit is used for converting a direct current power supply on a bus node into a charging power supply to charge a battery in a charging mode, wherein the charging power supply comprises a charging voltage and a charging current, the battery has a battery voltage, and the capacitance type power conversion circuit is used for converting the battery voltage into a power supply voltage in a power supply mode; wherein the DC power supply comprises a DC voltage and a DC current; the capacitive power conversion circuit is characterized by comprising:

a transfer switch circuit comprising a plurality of transfer switches coupled to one or more transfer capacitors; and

a conversion control circuit for generating a switch control signal to control the plurality of conversion switches;

in the charging mode, a power transmitting unit converts an input power to generate the dc power at the bus node, the power transmitting unit regulates the dc current at a predetermined dc current level, and the switch control signal correspondingly operates the plurality of switches during a plurality of charging conversion periods to periodically couple the one or more conversion capacitors between a pair of one or more charging proportional voltage nodes, the bus node, and a ground point, thereby making the level of the charging current a default current multiplication multiple of the predetermined dc current level in an open loop manner; wherein the charging power source is coupled to one of the one or more charging proportional voltage nodes;

and in the power supply mode, the switch control signal correspondingly operates the plurality of transfer switches in a plurality of power supply transfer periods, so that the one or more transfer capacitors are periodically and correspondingly coupled between one pair of one or more power supply proportional voltage nodes, the battery voltage and the grounding point, an output signal is generated at one node of the one or more power supply proportional voltage nodes, and a power supply voltage is generated at the bus node according to the output signal, thereby enabling the level of the power supply voltage to be a default boost multiple of the level of the battery voltage in an open loop mode.

2. The capacitive power conversion circuit of claim 1, wherein the conversion capacitor comprises first and second conversion capacitors, the plurality of power conversion periods comprises three power conversion periods; in the power supply mode, the switch control signal controls the plurality of transfer switches to periodically couple the first and second transfer capacitors between a pair of nodes of the plurality of power supply proportional voltage nodes, the battery voltage and the ground point in response to the voltage increase factor of 4/3 in the three power supply transfer periods, wherein the voltage across the first and second transfer capacitors is 2/3 and 1/3 of the battery voltage, respectively, in a steady state.

3. The capacitive power conversion circuit of claim 1, wherein the conversion capacitor comprises first and second conversion capacitors, the plurality of power conversion periods comprises two power conversion periods; in the power supply mode, the switch control signal controls the plurality of transfer switches to periodically couple the first and second transfer capacitors between a pair of nodes of the plurality of power supply proportional voltage nodes, the battery voltage and the ground point in response to the switching signal during the two power supply transfer periods, such that the voltage boost multiple is 3/2, wherein in a steady state, the voltage across the first and second transfer capacitors is 1/2 times the battery voltage.

4. The capacitive power conversion circuit of claim 1, wherein the conversion capacitor comprises first and second conversion capacitors, the plurality of charge conversion periods comprises first and second charge conversion periods; wherein in the charging mode, the conversion control circuit controls the plurality of conversion switches to respectively switch and electrically connect the first end of the first conversion capacitor between the DC voltage and the charging voltage in the first charging conversion period and the second charging conversion period, respectively switch and electrically connect the second end of the first conversion capacitor between the charging voltage and the grounding point in the first charging conversion period and the second charging conversion period, respectively switch and electrically connect the first end of the second conversion capacitor between the DC voltage and the charging voltage in the second charging conversion period and the first charging conversion period, respectively switch and electrically connect the second end of the second conversion capacitor between the charging voltage and the grounding point in the second charging conversion period and the first charging conversion period, so that the level of the charging current is 2 times of the predetermined DC level.

5. The capacitive power conversion circuit of claim 1, further comprising a linear regulation switch circuit for converting the output signal to generate the supply voltage at the bus node in the power mode, wherein the conversion control circuit further generates a linear regulation signal for linearly controlling a regulation switch of the linear regulation switch circuit such that the level of the supply voltage is regulated to a default output voltage level; and in the charging mode, the regulating switch is controlled to be in a conducting state.

6. The capacitive power conversion circuit of claim 5, wherein in the power mode, the conversion control circuit further determines the default boost multiple according to a battery voltage related signal, such that the output signal is greater than the power supply voltage, and the voltage across the input terminal and the output terminal of the regulating switch is less than a default voltage difference.

7. The capacitive power conversion circuit of claim 1, wherein The input power source conforms to a universal serial bus specification or a universal serial bus power supply specification, and The power supply voltage conforms to a universal serial bus On-The-Go specification.

8. A power conversion control method, comprising:

in a charging mode, a capacitor type power supply conversion circuit is used for converting a direct current power supply on a bus node into a charging power supply to charge a battery, wherein the charging power supply comprises a charging voltage and a charging current, and the battery has a battery voltage; and

under a power supply mode, converting the battery voltage into a power supply voltage by using the capacitive power conversion circuit;

wherein a power transmitting unit converts an input power to generate the DC power at the sink node, the DC power including a DC voltage and a DC current; wherein the capacitive power conversion circuit comprises a transfer switch circuit comprising a plurality of transfer switches coupled to one or more transfer capacitors;

wherein in the charging mode, the step of converting the dc power into the charging power comprises:

adjusting the DC current to a predetermined DC current level;

during a plurality of charging conversion periods, correspondingly operating the plurality of conversion switches to make the one or more conversion capacitors periodically and correspondingly coupled between a pair of nodes of one or more charging proportional voltage nodes, the direct current voltage and a grounding point, thereby making the level of the charging current be a default current increasing multiple of the preset direct current level in an open loop manner; and

coupling the charging power source to a node of the one or more charging proportional voltage nodes;

wherein in the power supply mode, the step of converting the battery voltage into the power supply voltage comprises:

during a plurality of power conversion periods, correspondingly operating the plurality of conversion switches to periodically and correspondingly couple the one or more conversion capacitors between a pair of one or more power proportional voltage nodes, the battery voltage and the grounding point to generate an output signal at one of the one or more power proportional voltage nodes; and

the supply voltage is generated at the bus node according to the output signal, such that the level of the supply voltage is a default boost multiple of the battery voltage level in an open loop manner.

9. The power conversion control method of claim 8, wherein the conversion capacitor comprises first and second conversion capacitors, the plurality of power conversion periods comprises three power conversion periods;

in the three power conversion periods, the first and second conversion capacitors are periodically coupled between a pair of nodes of the power proportional voltage nodes, the battery voltage and the grounding point, so that the voltage boost multiple is 4/3, wherein in a steady state, the voltage across the first and second conversion capacitors is 2/3 and 1/3 of the battery voltage, respectively.

10. The power conversion control method of claim 8, wherein the conversion capacitor comprises first and second conversion capacitors, the plurality of power conversion periods comprises two power conversion periods;

in the two power conversion periods, the first and second conversion capacitors are periodically coupled between a pair of nodes of the power proportional voltage nodes, the battery voltage and the grounding point, so that the voltage boost multiple is 3/2, wherein in a steady state, the voltage across the first and second conversion capacitors is 1/2 of the battery voltage.

11. The power conversion control method of claim 8, further comprising: in the power supply mode, a regulation switch of a linear regulation switch circuit is linearly controlled to convert the output signal to generate the power supply voltage on the bus node, wherein the level of the power supply voltage is regulated to a default output voltage level; and controlling the regulating switch to be in a conducting state in the charging mode.

12. The power conversion control method of claim 11, further comprising determining the default boost multiple according to a battery voltage related signal in the power supply mode, such that the output signal is greater than the power supply voltage, and the voltage across the input and output of the regulating switch is less than a default voltage difference.