High efficiency charging system and power conversion circuit therefor

Abstract

A high efficiency charging system and its power conversion circuit. The power conversion circuit includes an inductive switching power converter and a capacitive switching power converter. The inductive switching power converter is used to switch an inductor to convert a DC power source to generate a first power source. The capacitive switching power converter is used to switch a conversion capacitor to convert the first power source to generate a charging power source. The inductive switching power converter and the capacitive switching power converter determine to operate in a corresponding regulation mode or a corresponding short-circuit conduction mode according to a parameter of the DC power source.

Description

Technical Field

[0001] This invention relates to a charging system, specifically a high-efficiency charging system that simultaneously incorporates an inductor-switching power converter and a capacitor-switching power converter. The invention also relates to a power conversion circuit for use in a high-efficiency charging system. Background Technology

[0002] Figure 1 This invention discloses a prior art inductor switching power converter (inductor switching power converter 1001). The inductor switching power converter 1001 includes at least one inductor L and multiple switching elements (such as M11, M12). The multiple switching elements are used to switch the coupling relationship between the inductor L and a DC power supply (such as VBUS, IBUS) and a charging power supply (such as VCH, ICH) to convert the DC power supply to generate a charging power supply. For example, the inductor switching power converter 1001 is, for example, a buck switching power converter.

[0003] Figure 2 This invention discloses a prior art capacitor switching power converter (capacitor switching power converter 1002). The capacitor switching power converter 1002 includes at least one switching capacitor CF and multiple switching switches. The multiple switching switches are used to switch the coupling relationship between an inductor L and a DC power supply (such as VBUS) and a charging power supply (such as VCH, ICH) to convert the DC power supply to generate a charging power supply. For example, the capacitor switching power converter 1002 is, for instance, a capacitor voltage divider type capacitor switching power converter.

[0004] Figure 3 This invention discloses a prior art load switching circuit (load switching circuit 1003). When the power transmitting unit 100 corresponds to, for example, a power adapter compliant with the Universal Serial Bus Power Delivery Protocol (USB PD), the power transmitting unit 100 can directly provide corresponding charging power according to the battery state and charging stage. Specifically, the power transmitting unit 100 can adaptively adjust a constant voltage or a constant current to directly charge the battery 300 through the load switching circuit 1003. This reduces the number of stages in the power conversion circuit and improves the overall power conversion efficiency of the charging system. However, when the user uses, for example, an older power adapter that can only provide a constant voltage, the load switching circuit 1003 cannot provide adequate power conversion. Summary of the Invention

[0005] In one viewpoint, the present invention provides a power conversion circuit comprising: an inductor-switching power converter for switching an inductor to convert a DC power supply to generate a first power supply; and a capacitor-switching power converter for switching a switching capacitor to convert the first power supply to generate a charging power supply; wherein the inductor-switching power converter and the capacitor-switching power converter determine, based on a parameter of the DC power supply, to operate in one of a cross-combination of a corresponding adjustment mode or a corresponding short-circuit conduction mode; wherein in the corresponding adjustment mode, the inductor-switching power converter adjusts the corresponding first power supply to a corresponding preset target, or the capacitor-switching power converter adjusts the corresponding charging power supply to a corresponding preset target; wherein in the corresponding short-circuit conduction mode, the inductor-switching power converter short-circuit conducts the DC power supply to the first power supply, or the capacitor-switching power converter short-circuit conducts the first power supply to the charging power supply.

[0006] In one embodiment, the inductor-switching power converter includes a plurality of switching elements, which are used to switch the coupling relationship between the inductor and the DC power supply and the first power supply to convert the DC power supply to generate the first power supply; and the capacitor-switching power converter includes a plurality of switching switches, which are used to switch the coupling relationship between the switching capacitor and the first power supply and the charging power supply to convert the first power supply to generate the charging power supply; wherein the inductor-switching power converter has a first adjustment mode and a first short-circuit conduction mode, in the first adjustment mode, the plurality of switching elements switch the inductor to adjust the first power supply to a first preset target, and in the first short-circuit conduction mode, at least one of the corresponding switching elements switches the inductor to adjust the first power supply to a first preset target. The switching element is controlled to be turned on to short-circuit the DC power supply to the first power supply; wherein the capacitor switching power converter has a second adjustment mode and a second short-circuit conduction mode. In the second adjustment mode, a plurality of the switching switches switch the switching capacitor to adjust the charging power supply to a second preset target. In the second short-circuit conduction mode, at least one corresponding switching switch is controlled to be turned on to short-circuit the first power supply to the charging power supply; wherein the power conversion circuit determines whether the inductor switching power converter operates in the first adjustment mode or the first short-circuit conduction mode, and / or determines whether the capacitor switching power converter operates in the second adjustment mode or the second short-circuit conduction mode, based on the parameters of the DC power supply.

[0007] In one embodiment, the inductor-switching power converter operates in a first short-circuit conduction mode when the DC voltage of the DC power supply is lower than a first threshold, wherein the first threshold is related to a charging voltage of the charging power supply; or when the DC voltage is lower than a second threshold, the capacitor-switching power converter operates in a second short-circuit conduction mode, wherein the second threshold is related to the product of the charging voltage and a current amplification rate, wherein the current amplification rate is the ratio of a charging current of the charging power supply to a first current of the first power supply; or when the DC current of the DC power supply is constant, the inductor-switching power converter operates in the first short-circuit conduction mode; or when the DC current of the DC power supply is constant and the DC voltage is variable and can exceed the second threshold, the inductor-switching power converter operates in the first short-circuit conduction mode, and the capacitor-switching power converter operates in the second adjustment mode.

[0008] In one embodiment, the inductor switching power converter corresponds to a buck switching power converter or a buck-boost switching power converter.

[0009] In one embodiment, the DC power supply is provided by an AC-DC (AD-DC) converter.

[0010] In one embodiment, the capacitor switching power converter corresponds to a voltage divider capacitor switching power converter.

[0011] In one embodiment, a charging voltage of the charging power supply is 1 / 2 or 1 / 4 of a first voltage of the first power supply, and a charging current of the charging power supply is correspondingly 2 times or 4 times a first current of the first power supply.

[0012] In one embodiment, when the inductor switching power converter corresponds to a buck switching power converter, and the DC voltage is adjustable and lower than the first threshold, one of the upper bridge switches among the plurality of switching elements is fully turned on to short-circuit the DC power supply and the first power supply.

[0013] In one embodiment, when the DC voltage is lower than the second threshold, some of the multiple switching switches are fully turned on to short-circuit the first power supply and the charging power supply.

[0014] In one embodiment, the AC-DC converter is a power adapter compliant with the Universal Serial Bus Power Delivery Protocol (USB PD).

[0015] In one embodiment, the power conversion circuit further includes a control circuit for controlling the DC voltage and / or the DC current of the DC power supply via a communication interface.

[0016] In one embodiment, the communication interface corresponds to the D+ and D- signals of the Universal Serial Bus Protocol (USB), or to the CC1 and CC2 signals of the Universal Serial Bus Power Delivery Protocol (USB PD).

[0017] In one embodiment, the power conversion circuit further includes a control circuit for controlling the DC voltage and / or the DC current of the DC power supply, so that the power conversion circuit operates at a maximum efficiency operating point.

[0018] In another viewpoint, the present invention provides a charging system for converting an input power supply to generate a charging power supply, the charging system comprising: a power transmitting unit for converting the input power supply to generate a DC power supply; and a power conversion circuit as described above for converting the DC power supply to generate the charging power supply.

[0019] The series power conversion circuit proposed in this invention has an inductor-switching power converter and a capacitor connected in series. The power conversion circuit can adaptively control the inductor-switching power converter and the capacitor according to the relationship between the DC power supply and the charging power supply, and operate in combination in a typical switching adjustment mode or in a corresponding short-circuit conduction mode. This can improve the overall power conversion efficiency of the charging system through a flexible conversion method.

[0020] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, features, and effects achieved by the present invention. Attached Figure Description

[0021] Figure 1 This diagram shows a circuit schematic of a prior art inductor-switched power converter.

[0022] Figure 2 This diagram shows a circuit schematic of a prior art capacitor-switching power converter.

[0023] Figure 3 This shows a circuit diagram of another prior art load switching circuit.

[0024] Figure 4 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0025] Figure 5 A schematic diagram showing another embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein.

[0026] Figure 6A A schematic diagram showing a specific embodiment of the inductor-switching power converter according to the present invention is shown.

[0027] Figure 6B A schematic diagram showing a specific embodiment of the inductor-switching power converter according to the present invention is shown.

[0028] Figure 7 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0029] Figure 8 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0030] Figure 9 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0031] Figure 10 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0032] Figure 11 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0033] Figure 12 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein is presented.

[0034] Explanation of symbols in the diagram

[0035] 100, 100': Power transmission unit

[0036] 1004, 1005, 1007~1012: Charging System

[0037] 1001: Inductor Switching Power Converter

[0038] 1002: Capacitor-Switching Power Converter

[0039] 1003: Load Switching Circuit

[0040] 200, 200', 200”: Power conversion circuit

[0041] 205, 205”: Inductor-switched power converter

[0042] 206, 206”: Capacitor-Switching Power Converter

[0043] 207, 207': Control circuit

[0044] 208: Buck-Boost Switching Power Converter

[0045] 209: Boost Switching Power Converter

[0046] 300: Battery

[0047] 400: Cable

[0048] CB: Communication Interface

[0049] CF: Conversion Capacitor

[0050] ct1, ct2: Control signals

[0051] Dmax: Maximum duty cycle

[0052] I1: First current

[0053] IBAT: Battery Current

[0054] IBUS: Direct Current

[0055] ICH: Charging Current

[0056] k: Current amplification rate

[0057] L: Inductance

[0058] M11: Bridge switch

[0059] M12: Downbridge switch

[0060] M21, M22, M23, M24: Toggle switches

[0061] PH1, PH2: Charging transition periods

[0062] V1: First voltage

[0063] VCH: Charging voltage

[0064] VBAT: Battery voltage

[0065] VBUS: DC voltage

[0066] Vth1, Vth2: Thresholds Detailed Implementation

[0067] The accompanying drawings in this invention are all schematic and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

[0068] Please see Figure 4 See also Figure 5 , Figure 4 A schematic diagram showing an embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein (charging system 1004 and power conversion circuit 200).

[0069] The charging system 1004 includes a power transmitting unit 100, a power conversion circuit 200, and a battery 300. In one embodiment, the charging system 1004 may further include a removable cable 400. The power transmitting unit 100 is used to convert an input power supply Vs to generate a DC power supply (which includes a DC voltage VBUS and a DC current IBUS). In one embodiment, the power transmitting unit 100 may be, for example, an AC-DC converter. In this embodiment, the input power supply Vs may be, for example, an AC power supply, and the power transmitting unit 100 converts the input power supply Vs to generate a DC power supply. In a preferred embodiment, the power transmitting unit 100 may be, for example, a power adapter compliant with the Universal Serial Bus (USB) protocol.

[0070] Please also refer to Figure 5 , Figure 5 A schematic diagram showing another embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein (charging system 1005 and power conversion circuit 200') is displayed. In a preferred embodiment, the power transmitting unit 100' may be, for example, a power adapter conforming to the Serial Bus Power Delivery Protocol (USB PD). In one embodiment, the power conversion circuit 200' may request the power transmitting unit 100' to transmit a DC voltage VBUS and / or a DC current IBUS of a required DC power supply via a communication interface CB. In one embodiment, the communication interface CB may correspond, for example, to the D+ and D- signals of the Universal Serial Bus Protocol (USB), or to the CC1 and CC2 signals of the Universal Serial Bus Power Delivery Protocol (USB PD).

[0071] In another embodiment, the power conversion circuit 200' can obtain or measure the levels of the DC voltage VBUS and DC current IBUS transmitted by the power transmitting unit 100' via the communication interface CB. Specifically, the communication interface CB can be used for communication and control via the control circuit 207'.

[0072] Please continue reading. Figure 4 The power conversion circuit 200 is used to convert DC power to generate charging power (which includes charging voltage VCH and charging current ICH). In one embodiment, the power conversion circuit 200 includes an inductor-switched power converter 205, a capacitor-switched power converter 206, and a control circuit 207.

[0073] The inductor-switched power converter 205 includes at least one inductor L and multiple switching elements, the multiple switching elements (e.g. Figure 4 The upper bridge switch M11 and lower bridge switch M12 shown are used to switch the coupling relationship between the inductor and the DC power supply and the first power supply, so as to convert the DC power supply to generate the first power supply (i.e., the first voltage V1 and the first current I1).

[0074] In one embodiment, the inductor-switching power converter 205 has a first adjustment mode and a first short-circuit conduction mode. In the first adjustment mode, the control circuit 207 generates a control signal ct1 to control the switching of multiple switching elements of the inductor-switching power converter 205 to adjust the first power supply to a first preset target, such as adjusting the first voltage V1 to a preset voltage level or adjusting the first current I1 to a preset current level. Furthermore, in the first short-circuit conduction mode, the multiple switching elements controlled by the control circuit 207 are turned on to short-circuit the DC power supply and the first power supply.

[0075] Please continue reading. Figure 4 The capacitor switching power converter 206 includes at least one switching capacitor CF and multiple switching switches, the multiple switching switches (e.g. Figure 4 The switching switches M21, M22, M23, and M24 shown are used to switch the coupling relationship between the switching capacitor CF and the first power supply and the charging power supply, so as to switch the first power supply to generate the charging power supply.

[0076] In one embodiment, the capacitor switching power converter 206 has a second adjustment mode and a second short-circuit conduction mode. In the second adjustment mode, the control circuit 207 generates a control signal ct2 to control the switching of multiple switches of the capacitor switching power converter 206 to adjust the charging power supply to a second preset target, such as adjusting the charging voltage VCH to a preset voltage level or adjusting the charging current ICH to a preset current level. Furthermore, in the second short-circuit conduction mode, multiple switches in the control section of the capacitor switching power converter 206 are turned on to short-circuit the first power supply and the charging power supply.

[0077] Please continue reading. Figure 4 In one embodiment, the capacitor switching power converter 206 can be a voltage divider type capacitor switching power converter 206. That is, the charging voltage VCH of the charging power supply is 1 / k times the first voltage V1 of the first power supply, and the charging current ICH of the charging power supply is correspondingly a current amplification factor k times the first current I1 of the first power supply. In the embodiment of the voltage divider type capacitor switching power converter, k is a real number greater than 1. Specifically, in one embodiment, such as Figure 4 As shown in the configuration, the current amplification rate k can be 2, that is, the charging voltage VCH of the charging power supply is half of the first voltage V1 of the first power supply, and the charging current ICH of the charging power supply is correspondingly twice the first current I1 of the first power supply. In another embodiment, similar to Figure 4 The voltage divider concept allows the current amplification factor k to be 4, meaning that the charging voltage VCH of the charging power supply can be configured to be 1 / 4 of the first voltage V1 of the first power supply, and the charging current ICH of the charging power supply is correspondingly 4 times the first current I1 of the first power supply.

[0078] Specifically, in this embodiment, the control circuit 207 controls multiple switching switches M21, M22, M23, and M24 of the capacitor switching power converter 206, so that the first terminal of the switching capacitor CF is periodically switched during the first charging switching period (corresponding to, for example, PH1) and the second charging switching period (corresponding to, for example, PH2) respectively, and is electrically connected between the first voltage V1 and the charging voltage VCH. The second terminal of the switching capacitor CF is switched during the first charging switching period PH1 and the second charging switching period PH2 respectively, and is electrically connected between the charging voltage VCH and the ground point. As a result, the charging voltage VCH is half of the first voltage V1, and the charging current ICH is twice the first current I1.

[0079] It is worth noting that, in one embodiment, in the first short-circuit conduction mode, the plurality of switching elements in the aforementioned portion, in the first adjustment mode, are all switching elements used to switch the inductor L to perform inductor switching power conversion. From one perspective, in the first adjustment mode, the plurality of switching elements in the aforementioned portion are used to turn the inductor on and off for at least one period each in each switching cycle. In other words, the plurality of switching elements in the aforementioned portion are not dedicated to short-circuit conduction, but have the function of periodically switching the inductor L in the first adjustment mode.

[0080] On the other hand, in one embodiment, in the second short-circuit conduction mode, the plurality of switching switches in the second adjustment mode are all switching switches used to switch the conversion capacitor for capacitor switching power conversion. From one perspective, the plurality of switching switches in the second adjustment mode are used to turn the capacitor on and off for at least one period each in at least each switching cycle. In other words, the plurality of switching switches in the second adjustment mode are not dedicated to short-circuit conduction.

[0081] Please continue reading. Figure 4In one embodiment, the control circuit 207 determines whether the inductor-switching power converter 205 operates in a first regulation mode or a first short-circuit conduction mode, and / or controls the capacitor-switching power converter 206 to operate in a second regulation mode or a second short-circuit conduction mode, based on at least one of the parameters of the DC power supply and the charging power supply. In one embodiment, the parameters of the DC power supply and the charging power supply may be, for example, but not limited to, at least one of DC voltage VBUS, DC current IBUS, charging voltage VCH, and charging current ICH. In one embodiment, the control circuit 207 determines a combination of the above-described operating modes of the inductor-switching power converter 205 and the capacitor-switching power converter 206 based on the relationship between the parameters and at least one threshold. Alternatively, in another embodiment, the control circuit 207 determines a combination of the above-described operating modes of the inductor-switching power converter 205 and the capacitor-switching power converter 206 based on, for example, but not limited to, a relationship of magnitude or ratio between at least two of the DC voltage VBUS, DC current IBUS, charging voltage VCH, and charging current ICH. More specific embodiments will be described in detail later.

[0082] Please continue reading. Figure 4 In one embodiment, the inductor-switched power converter may correspond to, for example, as shown below. Figure 4 The step-down switching power converter (corresponding to 205) in the embodiment may be as follows: Figure 6A The buck-boost switching power converter shown (corresponding to 208), or Figure 6B The boost-type switching power converter shown is (corresponding to 209). In one viewpoint, the inductor-switching power converter can also be any other inductor-switching power architecture, as long as it has the function of short-circuiting its input and output (i.e., DC power supply and first power supply) by operating at least a portion of its switching elements used to switch the inductors, and is thus applicable to the present invention.

[0083] Please continue reading. Figure 4 In one specific embodiment, under the first short-circuit conduction mode, the control circuit 207 controls the upper bridge switch M11 to be constantly on. In another embodiment, under the first short-circuit conduction mode, the control circuit 207 controls the lower bridge switch M12 to be constantly off. In yet another embodiment, the lower bridge switching element may also be, for example, a diode. It should be noted that, from one perspective, under the first short-circuit conduction mode, the short-circuit conduction path between the DC power supply and the first power supply simultaneously includes both the constantly on upper bridge switch M11 and the inductor L.

[0084] Please continue reading. Figure 6A In this embodiment, under the first short-circuit conduction mode, the input upper bridge switch M13 and the output upper bridge switch M15 are controlled to be constantly conducting, and the input lower bridge switch M14 and the output lower bridge switch M16 are controlled to be constantly not conducting.

[0085] Please continue reading. Figure 6B In this embodiment, under the first short-circuit conduction mode, the upper bridge switch M17 is controlled to be constantly conducting, and the lower bridge switch M18 is controlled to be constantly non-conducting.

[0086] On the other hand, please continue reading Figure 4 In one specific embodiment, under the second short-circuit conduction mode, the control circuit 207 controls the switching switches M21 and M22 to be constantly on, and controls the switching switch M24 to be constantly off. In one embodiment, under the second short-circuit conduction mode, the switching switch M23 can be either constantly off or constantly on.

[0087] It should be noted that the following embodiments will be described as follows: Figure 4 The step-down inductor switching power converter and the voltage divider capacitor switching power converter described in the embodiments continue to illustrate other detailed embodiments, but are not intended to limit the scope of the invention.

[0088] Figure 7 A schematic diagram showing an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1007 and power conversion circuit 200) is shown. This embodiment is based on... Figure 4 In this embodiment, the DC voltage VBUS transmitted by the power transmitting unit 100 is, for example, 9V, and the DC current IBUS can be output up to 2.3A. In other words, in this embodiment, the maximum power output by the power transmitting unit 100 can reach approximately 21W. Furthermore, in this embodiment, the battery voltage VBAT is, for example, 3.5V (corresponding to the charging voltage VCH), and a constant current mode can be adopted to generate a charging current ICH (corresponding to the battery current IBAT) to charge the battery 300. Additionally, if the capacitor switching power converter 206 is controlled to operate in the second adjustment mode, under the aforementioned current amplification factor k of 2, the first voltage V1 (twice the charging voltage VCH) will be 7V. In this case, the difference between the DC voltage VBUS and the first voltage V1 is still greater than 0, and the condition for the capacitor switching power converter 206 to operate in the second adjustment mode is met. In one embodiment, the control circuit 207 can determine that the inductor switching power converter 205 operates in the first adjustment mode, and the capacitor switching power converter 206 operates in the second adjustment mode. In this case, the battery 300 can be charged at maximum power. Specifically, in this embodiment, in the first adjustment mode, the DC voltage VBUS is 9V, the DC current IBUS can be output up to 2.3A, the first voltage V1 is 7V, and the first current I1 can reach 3A. In the second adjustment mode, the charging voltage VCH is 3.5V, and the charging current ICH can reach 6A.

[0089] Figure 8A schematic diagram showing an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1008 and power conversion circuit 200) is shown. This embodiment is based on... Figure 4 In this embodiment, the DC voltage VBUS transmitted by the power transmitting unit 100 can reach, for example, 9V, and the DC current IBUS can be output, for example, up to 2A. In other words, in this embodiment, the maximum power output by the power transmitting unit 100 can reach 18W. In this embodiment, the battery voltage VBAT is, for example, 3.5V (corresponding to the charging voltage VCH), and a constant current mode can be adopted to generate a charging current ICH to charge the battery 300. Furthermore, if the capacitor switching power converter 206 is controlled to operate in the second adjustment mode, under the aforementioned current amplification factor k is 2, the first voltage V1 (twice the charging voltage VCH) will be 7V. In this case, the difference between the DC voltage VBUS and the first voltage V1 is still greater than 0, and the condition for the capacitor switching power converter 206 to operate in the second adjustment mode is met.

[0090] In one embodiment, such as Figure 8 As shown, the control circuit 207 can determine that the inductor-switching power converter 205 operates in the first short-circuit conduction mode (M11 is always conducting, and M12 is always non-conducting, indicated by a thick solid line), and the capacitor-switching power converter 206 operates in the second regulation mode. Specifically, in this embodiment, the power transmitting unit 100 provides the maximum constant current, i.e., the DC current IBUS is 2A. When the inductor-switching power converter 205 operates in the first short-circuit conduction mode, the first current I1 is also 2A. When the capacitor-switching power converter 206 operates in the second regulation mode, the charging current ICH is 4A, and both the DC voltage VBUS and the first voltage V1 are equal to 7V.

[0091] It is worth noting that, in this case, since the inductor switching power converter 205 does not perform switching power conversion, the switching energy loss is reduced. Therefore, the charging system 1008 can charge the battery 300 with a higher power conversion efficiency. When the power transmitting unit 100 corresponds to another battery-powered mobile device or a mobile power bank, the battery life of the power transmitting unit 100 itself can be extended. In addition, the power conversion circuit 200 located in a mobile device can generally reduce its operating temperature as a result.

[0092] In another embodiment, the inductor switching power converter 205 has a maximum duty cycle Dmax. When the relationship between the DC voltage VBUS and the first voltage V1 causes the inductor switching power converter 205 to operate in the first regulation mode, the maximum duty cycle Dmax will be exceeded. In this case, it can also be determined that the inductor switching power converter 205 operates in the first short-circuit conduction mode.

[0093] Figure 9 A schematic diagram showing an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1009 and power conversion circuit 200) is shown. This embodiment is based on... Figure 4 In this embodiment, the DC voltage VBUS transmitted by the power transmitting unit 100 is, for example, 5V, and the DC current IBUS can be output up to 2.1A. In other words, in this embodiment, the maximum power output by the power transmitting unit 100 can reach 10.5W. In this embodiment, the battery voltage VBAT is, for example, 3.5V (corresponding to the charging voltage VCH), and a constant current mode can be adopted to generate a charging current ICH to charge the battery 300. Furthermore, if the capacitor switching power converter 206 is controlled to operate in the second regulation mode, under the aforementioned current amplification factor k is 2, the first voltage V1 (twice the charging voltage VCH) will be 7V. In this case, the difference between the DC voltage VBUS and the first voltage V1 is less than 0, that is, the condition for the capacitor switching power converter 206 to operate in the second regulation mode is not met.

[0094] Therefore, in one embodiment, as Figure 9 As shown, the control circuit 207 can determine that the inductor-switching power converter 205 operates in the first adjustment mode, and the capacitor-switching power converter 206 operates in the second short-circuit conduction mode (M21 and M22 are always conducting, indicated by thick solid lines, and M23 and M24 are always non-conducting, indicated by blank lines). In this case, the battery 300 can be charged at maximum power. Specifically, in this embodiment, the DC voltage VBUS is supplied with 5V. When the inductor-switching power converter 205 operates in the first adjustment mode, the first current I1 is adjusted to 3A, while when the capacitor-switching power converter 206 operates in the second short-circuit conduction mode, the first voltage V1 is the same as the battery voltage VBAT, both being 3.5V. In this case, the corresponding DC current IBUS is 2.1A, that is, in this embodiment, the battery 300 is charged at maximum power.

[0095] Figure 10 A schematic diagram showing an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1010 and power conversion circuit 200) is shown. This embodiment is based on... Figure 4 In this embodiment, the DC voltage VBUS transmitted by the power transmitting unit 100 can, for example, be up to 5V, and the DC current IBUS can, for example, be up to 2A. In other words, in this embodiment, the maximum power output by the power transmitting unit 100 can reach 10W. In this embodiment, the voltage conditions of the power transmitting unit 100 are related to... Figure 9 The implementation is similar, that is, the conditions for the capacitor switching power converter 206 to operate in the second regulation mode are not met.

[0096] Therefore, in one embodiment, as Figure 10 As shown, the control circuit 207 can determine that the inductor-switching power converter 205 operates in the first short-circuit conduction mode, and the capacitor-switching power converter 206 operates in the second short-circuit conduction mode. The control circuit 207 can request the power transmitting unit 100 to output a constant current through the aforementioned communication interface CB. Specifically, in this embodiment, the DC current IBUS of the power transmitting unit 100 is adjusted to 2A. In both the first and second short-circuit conduction modes, the first current I1 and the charging current ICH are also 2A, and the first voltage V1 and the DC voltage VBUS are both equal to 3.5V, which corresponds to the battery voltage VBAT. In other words, the charging system 1010 operates in direct charging mode, and the power transmitting unit 100 directly charges the battery 300 with a constant current.

[0097] Figure 11 This diagram shows an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1011 and power conversion circuit 200'). This embodiment is based on... Figure 4 In this embodiment, the power transmitting unit 100 can optionally output a DC voltage VBUS of up to 5V and a corresponding DC current IBUS of up to 2A in a low-power mode. In other words, in this embodiment, the maximum power output of the power transmitting unit 100 in this mode can reach 10W. In a high-power mode, the transmitted DC voltage VBUS can output up to 9V and the corresponding DC current IBUS of up to 2A. In other words, in this embodiment, the maximum power output of the power transmitting unit 100 in this high-power mode can reach 18W. In this embodiment, the battery voltage VBAT is, for example, 3.5V (corresponding to the charging voltage VCH), and a constant current mode can be adopted to generate a charging current ICH to charge the battery 300. Furthermore, if the control capacitor switching power converter 206 operates in the second regulation mode, under the aforementioned current amplification factor k is 2, the first voltage V1 (twice the charging voltage VCH) will be 7V, that is, the DC voltage VBUS must be greater than or equal to 7V.

[0098] Therefore, in this embodiment, as Figure 11As shown, optionally, the control circuit 207 determines that the inductor-switching power converter 205 operates in a first short-circuit conduction mode, and the capacitor-switching power converter 206 operates in a second regulation mode. Furthermore, the control circuit 207 can request the power transmitting unit 100 to output a constant current and operate in a high-power mode via the aforementioned communication interface CB. Specifically, in this embodiment, the DC current IBUS of the power transmitting unit 100 is adjusted to 2A. In the first short-circuit conduction mode and the second regulation mode, the first current I1 and the charging current ICH are 2A and 4A respectively, and the first voltage V1 and the DC voltage VBUS are both equal to 7V, which corresponds to twice the battery voltage VBAT.

[0099] From one perspective, based on the description of the foregoing embodiments, the principle by which the control circuit 207 determines when the inductor-switched power converter 205 operates in the first short-circuit conduction mode, or determines when the capacitor-switched power converter 206 operates in the second short-circuit conduction mode, can be summarized as follows.

[0100] In one embodiment, when the DC voltage VBUS of the DC power supply is lower than a first threshold Vth1, the inductor-switched power converter 205 operates in a first short-circuit conduction mode. In one embodiment, the first threshold Vth1 is related to a first voltage V1. When the capacitor-switched power converter 206 operates in a second regulation mode, the first voltage V1 is k times the battery voltage VBAT; therefore, in one embodiment, the first threshold Vth1 is related to k*VBAT. Furthermore, when the capacitor-switched power converter 206 operates in a second short-circuit conduction mode, the first voltage V1 is equal to the battery voltage VBAT; therefore, in one embodiment, the first threshold Vth1 is related to VBAT.

[0101] Specifically, assuming the maximum duty cycle of the inductor-switched power converter 205 in the first regulation mode is Dmax, in an embodiment where the capacitor-switched power converter 206 operates in the second regulation mode, the first threshold Vth1 can be obtained from the following formula:

[0102] Vth1 = VBAT * k / Dmax, where Dmax is a real number greater than or equal to 0 and less than 1.

[0103] Furthermore, when the power transmission unit 100 can transmit a constant DC current IBUs, such as Figure 8 or Figure 10 As shown in the embodiments, the inductor switching power converter 205 can also be controlled to operate in a first short-circuit conduction mode, as previously described, which can improve the power conversion efficiency of the charging system.

[0104] From another perspective, in one embodiment, when the power transmitting unit 100 can transmit a constant DC current IBUs and the DC voltage VBUS is variable and can exceed VBAT*k, optionally, the inductor switching power converter 205 can be controlled to operate in a first short-circuit conduction mode, and the capacitor switching power converter 206 can be controlled to operate in a second regulation mode.

[0105] On the other hand, when the DC voltage VBUS of the DC power supply is lower than the second threshold Vth2, the capacitor-switching power converter 206 operates in a second short-circuit conduction mode, where the second threshold Vth2 is related to the battery voltage VBAT. When the capacitor-switching power converter 206 operates in the second regulation mode, the first voltage V1 is equal to k times the battery voltage VBAT, and the DC voltage VBUS is greater than or equal to the first voltage V1. Therefore, in one embodiment, the second threshold Vth2 is related to k*VBAT; specifically, in a preferred embodiment, Vth2 ≥ k*VBAT.

[0106] Furthermore, since the maximum duty cycle Dmax is usually less than 1, when the inductor switching power converter 205 operates in the first regulation mode, the DC voltage VBUS needs to be greater than the first voltage V1. Therefore, in a preferred embodiment, the first threshold Vth1 is higher than the second threshold Vth2.

[0107] Specifically Figure 9 and Figure 10 In one embodiment, when the DC voltage VBUS is too low to meet the conditions for the capacitor switching power converter 206 to operate in the second regulation mode, the control circuit 207 may decide to control the capacitor switching power converter 206 to operate in the second short-circuit conduction mode.

[0108] In summary, in one embodiment, when the inductor switching power converter 205 corresponds to a buck switching power converter, and the DC voltage VBUS is adjustable and lower than the first threshold Vth1, the upper bridge switch among the multiple switching elements is fully turned on to short-circuit the first power supply and the charging power supply.

[0109] In one embodiment, when the DC voltage VBUS is lower than the second threshold Vth2, some of the multiple switching switches are fully turned on to short-circuit the first power supply and the charging power supply.

[0110] In one embodiment, the aforementioned control circuit 207 may, for example, correspond to a microcontroller for controlling the DC voltage VBUS and / or the DC current IBUS of the DC power supply via a communication interface.

[0111] Furthermore, according to the combination of the aforementioned various operating modes, in one embodiment, the control circuit 207 can be used to control the DC voltage VBUS and / or the DC current IBUS of the DC power supply, so that the power conversion circuit 200 operates at the maximum efficiency operating point.

[0112] Figure 12 This diagram shows an embodiment of a high-efficiency charging system and its power conversion circuit according to the present invention (charging system 1012 and power conversion circuit 200”). Similar to the previous embodiments, in this embodiment, the inductor L and the switching capacitor CF are not included in the power conversion circuit 200”. In other words, the inductor-switching power converter 205” is used to switch the inductor L, and the capacitor-switching power converter 206” is used to switch the switching capacitor CF. In one embodiment, the inductor-switching power converter 205”, the capacitor-switching power converter 206”, and the control circuit 207 are integrated into a single integrated circuit; that is, the power conversion circuit 200” corresponds to this integrated circuit.

[0113] As mentioned above, Figures 4-5 , Figures 7-12 The embodiments all demonstrate the operation of the present invention using a step-down inductor switching power converter and a voltage divider capacitor switching power converter. In other embodiments, the relationship between the multiplier k and the threshold can be adjusted according to the actual combination of power converters. Those skilled in the art can deduce this from the spirit of the present invention, and it will not be elaborated here.

[0114] This invention provides a power conversion circuit consisting of an inductor-switching power converter and a capacitor-switching power converter connected in series. The circuit can adaptively select the combination of operating modes of the inductor-switching power converter and the capacitor-switching power converter according to the requirements of DC power supply, battery voltage and state, so as to charge the battery in the maximum power or high efficiency mode, or to make the power conversion circuit operate at a maximum efficiency operating point.

[0115] The present invention has been described above with reference to preferred embodiments. However, the above description is only intended to facilitate understanding of the invention by those skilled in the art and is not intended to limit the broadest scope of the invention. The described embodiments are not limited to individual application and can also be used in combination. For example, two or more embodiments can be used in combination, and some components of one embodiment can be used to replace corresponding components in another embodiment. Furthermore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations. For example, the phrase "processing or calculating based on a signal or generating an output result" in the present invention is not limited to the signal itself, but also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and / or proportional conversion on the signal, and then processing or calculating based on the converted signal to generate an output result. Therefore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations, and there are many combinations, which will not be listed here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A power conversion circuit, characterized in that, Include: An inductor-switching power converter includes a plurality of first switching elements for switching an inductor to convert DC power into a first power supply; and A capacitor-type switching power converter includes multiple second switching elements for switching a switching capacitor to convert the first power supply into a charging power supply. The inductor-switching power converter and the capacitor-switching power converter are configured to operate in one of a set of operating combinations based on the DC power supply and the charging power supply, the set of operating combinations including: Combination 1: When the DC voltage of the DC power supply is higher than the DC threshold voltage, and the DC voltage is controlled and adjusted to a first predetermined voltage level higher than the DC threshold voltage, the inductor-switched power converter is configured to operate in a first adjustment mode, and the capacitor-switched power converter is configured to operate in a second adjustment mode, wherein the DC threshold voltage is related to the product of a charging voltage of the charging power supply and a current amplification ratio, and the current amplification ratio is the ratio of a charging current of the charging power supply to a first current of the first power supply in the second adjustment mode; Combination 2: When the DC voltage of the DC power supply is higher than the DC threshold voltage, and the DC current of the DC power supply is controlled and adjusted to a first predetermined current level, the inductor switching power converter is configured to operate in a first bypass mode, and the capacitor switching power converter is configured to operate in a second regulation mode. Combination 3: When the DC voltage of the DC power supply is lower than the DC threshold voltage, and the DC voltage is controlled and adjusted to a second predetermined voltage level higher than the charging voltage, the inductor-switched power converter is configured to operate in a first regulation mode, and the capacitor-switched power converter is configured to operate in a second bypass mode; and Combination 4: When the DC voltage of the DC power supply is lower than the DC threshold voltage and the DC current is controlled to be adjusted to a second predetermined current level, the inductor switching power converter is configured to operate in a first bypass mode and the capacitor switching power converter is configured to operate in a second bypass mode. In the first adjustment mode, the plurality of first switching elements are configured to operatively switch the inductor according to a first switching frequency to perform power conversion based on the switching inductor, thereby adjusting the first power supply to a first predetermined target level. In the second adjustment mode, the plurality of second switching elements are configured to operatively switch the switching capacitor according to a second switching frequency to perform power conversion based on the switching capacitor, thereby adjusting the charging power to a second predetermined target level. Among them, the plurality of first switching elements includes at least one first bypass switch. In the first bypass mode, the at least one first bypass switch is controlled to be continuously turned on, thereby bypassing the DC power supply to the first power supply. Among the plurality of second switching elements, at least one second bypass switch is included. In the second bypass mode, the at least one second bypass switch is controlled to be continuously turned on, thereby bypassing the first power supply to the charging power supply. Each of the at least one first bypass switch is shared in at least one sub-mode of the first regulation mode to operatively switch the inductor according to the first switching frequency, and at least a portion of the current of the inductor flows through each of the first bypass switches. In the second regulation mode, each of the at least one second bypass switch is shared to operatively switch the switching capacitor according to the second switching frequency, and at least a portion of the current in the switching capacitor flows through each of the second bypass switches.

2. The power conversion circuit as described in claim 1, wherein, When the inductor-switched power converter is configured to operate in the first regulation mode, the DC voltage of the DC power supply is higher than the DC threshold voltage to a certain extent, such that the duty cycle of the inductor-switched power converter does not exceed its maximum operable duty cycle.

3. The power conversion circuit as described in claim 1, wherein, The DC power supply is provided by an AC-DC converter.

4. The power conversion circuit as described in claim 1, wherein, This capacitor switching power converter is a voltage divider type capacitor switching power converter.

5. The power conversion circuit as described in claim 4, wherein, The charging voltage of the charging power supply is 1 / 2 or 1 / 4 of the first voltage of the first power supply, and the charging current of the charging power supply is correspondingly 2 times or 4 times the first current of the first power supply.

6. The power conversion circuit as described in claim 1, wherein, The inductor-switched power converter is configured as a step-down switching power converter, wherein the plurality of first switching elements include an upper bridge switch, which is coupled between the DC power supply and one end of the inductor, and the other end of the inductor is coupled to the first power supply; wherein the at least one first bypass switch is the upper bridge switch; wherein, in the first bypass mode, the upper bridge switch is controlled to be continuously turned on, thereby allowing the DC power supply to bypass to the first power supply through the inductor.

7. The power conversion circuit as described in claim 3, wherein, This AC-DC converter is a power adapter compliant with the Universal Serial Bus power delivery protocol.

8. The power conversion circuit as described in claim 1, wherein, It also includes a control circuit for controlling the DC voltage and / or the DC current of the DC power supply via a communication interface; The communication interface is configured to communicate with a power transmitting unit that generates the DC power supply; wherein the communication interface is the D+ and D- signals in the Universal Serial Bus protocol, or the CC1 and CC2 signals in the Universal Serial Bus power transmission protocol.

9. The power conversion circuit as described in claim 1, wherein, It also includes a control circuit for controlling the DC voltage and / or the DC current of the DC power supply, so that the power conversion circuit operates at a maximum efficiency operating point.

10. A charging system for converting an input power supply to generate a charging power supply, characterized in that, The charging system includes: A power transmission unit for converting the input power to generate a DC power supply; and The power conversion circuit as described in any one of claims 1 to 9 is used to convert the DC power supply to generate the charging power supply.

Images