TWI770985B - High efficiency charging system and power conversion circuit thereof - Google Patents

Abstract

A power conversion circuit includes an inductive switching power converter, a capacitve switching power converter. The inductive switching power converter switches an inductor to converter a DC power to a first power. The capacitive switching power converter switches a capacitor to convert the first power to a charging power for charging a battery. The inductive switching power converter and the the capacitive switching power converter are controlled to operate in a combination of their corresponding regulation modes and corresponding bypass modes according to a parameter of the DC power.

Description

High-efficiency charging system and its power conversion circuit

The present invention relates to a charging system, in particular, to a high-efficiency charging system having both an inductance-switched power converter and a capacitance-switched power converter. The present invention also relates to a power conversion circuit for a high-efficiency charging system.

FIG. 1 shows a prior art inductance switching power converter (inductance switching power converter 1001 ). The inductance switching power converter 1001 includes at least one inductor L and complex switching elements (eg, M11 and M12 ), which are used to switch the inductance The coupling relationship between L and the DC power source (eg VBUS, IBUS) and the charging power source (eg VCH, ICH) is to convert the DC power source to generate the charging power source. For example, the inductance switching power converter 1001 is, for example, a buck switching converter.

FIG. 2 shows a prior art capacitance-switched power converter (capacitance-switched power converter 1002 ). The capacitance-switched power converter 1002 includes at least one conversion capacitor CF and a plurality of switches for switching the inductor L and the DC power supply ( Such as VBUS) and the coupling relationship of the charging power (such as VCH, ICH), to convert the DC power to generate the charging power. For example, the capacitor-switched power converter 1002 is, for example, a capacitor-switched power converter of a voltage divider type (capacitor voltage divider).

FIG. 3 shows a load switch circuit (load switch circuit 1003 ) of the prior art. When the power transmission unit 100 corresponds to, for example, a power adapter compliant with the Universal Serial Bus Power Delivery Protocol (USB PD), the power transmission unit 100 state and charging stage, and directly provide the corresponding charging power. Specifically, the power transmission unit 100, for example, an adaptable constant voltage or constant current, directly charges the battery 300 through the load switch circuit 1003, thereby , which can reduce the number of stages of the power conversion circuit and improve the power conversion efficiency of the overall charging system. However, when the user uses, for example, an older power adapter that can only provide constant voltage, the load switch circuit 1003 cannot provide proper power conversion.

In view of the above-mentioned shortcomings of the prior art, the present invention proposes a series-connected power conversion circuit, which has an inductive switching power converter and a capacitor connected in series with each other. The power conversion circuit can adapt to the relationship between the DC power supply and the charging power supply. The inductive switching power converter and the capacitor are selectively controlled, and the combined operation is in the typical switching regulation mode, or in the corresponding short-circuit conduction mode, so that the overall power supply of the charging system can be improved by the flexible conversion method. conversion efficiency.

In one aspect, the present invention provides a power conversion circuit, comprising: an inductance-switching power converter for switching an inductance to convert a DC power supply to generate a first power supply; and a capacitance-switching power converter for switching A conversion capacitor is used to convert the first power source to generate a charging power source; wherein the inductance switching power converter and the capacitance switching power converter are determined to operate in a corresponding regulation mode or a corresponding short-circuit conduction according to a parameter of the DC power supply One of the cross combinations of modes; wherein in the corresponding adjustment mode, the inductance switching power converter adjusts the corresponding first power supply to a corresponding preset target, or the capacitance switching power converter adjusts the corresponding charging power supply to a corresponding preset target; wherein in the corresponding short-circuit conduction mode, the inductance-switching power converter short-circuits conducts the DC power supply to the first power supply, or the capacitance-switching power converter short-circuits conducts the first power supply to the first power supply Charger.

In one embodiment, the inductance switching power converter includes a plurality of switching elements, and the plurality of the switching elements are used to switch the coupling relationship between the inductance, the DC power supply and the first power supply, so as to convert the DC power supply to generate the first power supply. a power source; and the capacitor switching power converter includes a plurality of switching switches, and the plurality of switching switches are used for switching the coupling relationship between the switching capacitor, the first power source and the charging power source, so as to convert the first power source to generate the charging power source; The inductance-switching power converter has a first regulation mode and a first short-circuit conduction mode. In the first regulation mode, a plurality of the switching elements switch the inductance to regulate the first power supply to a first predetermined target. In the first short-circuit conduction mode, the corresponding at least one switching element is controlled to be turned on, so as to short-circuit the DC power supply to the first power supply; wherein the capacitor-switched power converter has a second regulation mode and a second short-circuit conduction mode , in the second adjustment mode, a plurality of the switch switches switch the conversion capacitor to adjust the charging power source to a second preset target, and in the second short-circuit conduction mode, the corresponding at least one switch is controlled to be turned on, Conducting the first power supply to the charging power supply in a short circuit; wherein the power conversion circuit determines that the inductance switching power converter operates in the first regulation mode or the first short-circuit conduction mode according to the parameter of the DC power supply, and/ Or it is determined that the capacitor-switched power converter operates in the second regulation mode or the second short-circuit conduction mode.

In one embodiment, when a DC voltage of the DC power source is lower than a first threshold, the inductive switching power converter operates in the first short-circuit conduction mode, wherein the first threshold is related to the charging power source a charging voltage; or when the DC voltage is lower than a second threshold, the capacitor-switched power converter operates in the second short-circuit conduction mode, wherein the second threshold is related to the product of the charging voltage and a current amplification factor, Wherein the current amplification rate is a ratio of a charging current of the charging power source to a first current of the first power source; or when a DC current of the DC power source is constant, the inductance switching power converter operates in the first power source short-circuit conduction mode; or when a DC current of the DC power source is constant, and the DC voltage is variable and can exceed the second threshold, the inductance-switched power converter operates in the first short-circuit conduction mode, and the capacitor The switching power converter operates in the second regulation mode.

In one embodiment, the inductance switching power converter corresponds to a buck switching power converter or a buck-boost switching power converter.

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

In one embodiment, the capacitor-switched power converter corresponds to a voltage-dividing capacitor-switched power converter.

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

In one embodiment, when the inductive switching power converter corresponds to a step-down switching power converter, and the DC voltage is programmable and is lower than the first threshold, one of the plurality of switching elements is The upper bridge switch is completely turned on to short-circuit the DC power supply and the first power supply.

In one embodiment, when the DC voltage is lower than the second threshold, some of the switches in the plurality of switching switches are completely turned on to short-circuit the first power source and the charging power source.

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

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

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

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

In another aspect, the present invention provides a charging system for converting an input power to generate a charging power, the charging system comprising: a power sending unit for converting the input power to generate a DC power; and if requested Any one of the power conversion circuits of items 1 to 13 is used for converting the DC power to generate the charging power.

The following describes in detail with specific embodiments, when it is easier to understand the purpose, technical content, characteristics and effects of the present invention.

The drawings in the present invention are schematic, mainly intended to represent the coupling relationship between the circuits and the relationship between the signal waveforms, and the circuits, signal waveforms and frequencies are not drawn to scale.

Please refer to FIG. 4 and FIG. 5 at the same time. FIG. 4 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein (charging system 1004 and power conversion circuit 200 ) of the present invention.

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

Please also refer to FIG. 5. FIG. 5 shows a schematic diagram of another embodiment of the high-efficiency charging system and the power conversion circuit therein (charging system 1005 and power conversion circuit 200') of the present invention. In a preferred embodiment, the power transmission unit 100 ′ can be, for example, a power adapter compliant with the Serial Bus Power Delivery Protocol (USB PD). The power transmitting unit 100 ′ transmits the DC voltage VBUS of the DC power supply and/or the DC current IBUS of the DC power supply that meets the requirements. In one embodiment, the communication interface CB corresponds to, for example, the D+ and D- signals of the Universal Serial Bus Protocol (USB), or the CC1 and CC2 signals of the Universal Serial Bus Power Delivery Protocol (USB PD).

In another embodiment, the power conversion circuit 200' can obtain or measure the levels of the DC voltage VBUS and the DC current IBUS sent by the power transmission unit 100' through the communication interface CB. The above-mentioned communication interface CB can be specifically communicated and controlled by the control circuit 207'.

Please continue to refer to FIG. 4 , the power conversion circuit 200 is used for converting the DC power to generate the charging power (which includes the charging voltage VCH and the charging current ICH). The power converter 206 and the control circuit 207 are switched.

The inductance switching power converter 205 includes at least one inductor L and a plurality of switching elements. The complex switching elements (eg, the upper bridge switch M11 and the lower bridge switch M12 shown in FIG. 4 ) are used to switch the coupling between the inductance and the DC power supply and the first power supply. A first power source (ie, a first voltage V1 and a first current I1 ) is generated by converting the DC power source.

In one embodiment, the inductance-switched power converter 205 has a first regulation mode and a first short-circuit conduction mode. In the first regulation mode, the control circuit 207 generates a control signal ct1 to control the complex switching elements of the inductance-switched power converter 205 . to adjust the first power supply to the first preset target, for example, adjust the first voltage V1 to a preset voltage level, or adjust the first current I1 to a preset current level. In addition, in the first short-circuit conduction mode, the control circuit 207 controls part of the plurality of switching elements to conduct, so as to short-circuit the DC power supply and the first power supply.

Please continue to refer to FIG. 4 , the capacitor switching power converter 206 includes at least one switching capacitor CF and a plurality of switching switches. The coupling relationship between the first power source and the charging power source is to convert the first power source to generate the charging power source.

In one embodiment, the capacitor-switched power converter 206 has a second regulation mode and a second short-circuit conduction mode. In the second regulation mode, the control circuit 207 generates a control signal ct2 to control the plurality of switches of the capacitor-switched power converter 206 . to adjust the charging power source to the 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. In addition, in the second short-circuit conduction mode, the plurality of switches in the control portion of the capacitor-switched power converter 206 are turned on, so as to short-circuit the first power source and the charging power source.

Please continue to refer to FIG. 4 , in one embodiment, the capacitor-switched power converter 206 may correspond to a voltage divider-type capacitor-switched power converter 206 . That is, the charging voltage VCH of the charging power source is 1/k times the first voltage V1 of the first power source, and the charging current ICH of the charging power source is correspondingly the current amplification factor of the first current I1 of the first power source, k times, In the embodiment of the voltage-dividing capacitor-switched power converter, k is a real number greater than 1. Specifically, in one embodiment, as shown in the configuration of FIG. 4 , the current amplification factor k may be 2, that is, the charging voltage VCH of the charging power source is 1/2 of the first voltage V1 of the first power source, And the charging current ICH of the charging power source is correspondingly twice the first current I1 of the first power source. In another embodiment, similar to the voltage dividing concept in FIG. 4 , the current amplification rate k can be 4, that is, the charging voltage VCH of the charging power source can be configured to be 1/4 of the first voltage V1 of the first power source, And the charging current ICH of the charging power source is correspondingly four times the first current I1 of the first power source.

Specifically, in this embodiment, the control circuit 207 controls the complex switching switches M21, M22, M23, M24 of the capacitor switching power converter 206, so that the first end of the switching capacitor CF is periodically in the first charging switching period (corresponding to the first charging switching period). In such as PH1) and the second charging conversion period (corresponding to, for example, PH2), the switching is respectively correspondingly switched to be electrically connected between the first voltage V1 and the charging voltage VCH, and the second end of the conversion capacitor CF is switched in the first charging conversion The period PH1 and the second charging transition period PH2 are respectively switched and electrically connected between the charging voltage VCH and the ground point, whereby the charging voltage VCH is 1/2 of the first voltage V1, and the charging current ICH is correspondingly It is twice the first current I1.

It should be noted that, in one embodiment, in the first short-circuit conduction mode, the part of the plurality of switching elements is used to switch the inductor L to perform the inductance switching power conversion in the first adjustment mode. The switching element, from one point of view, the part of the plurality of switching elements is used to turn on and turn off the inductor for at least a period of time during at least each switching period in the first adjustment mode. In other words, the above-mentioned part of the plurality of switching elements are not dedicated for short-circuit conduction, but have the function of periodically switching the inductance L in the first adjustment mode.

On the other hand, in one embodiment, in the second short-circuit conduction mode, the part of the plurality of switches in the second regulation mode are all used to switch the switching capacitor to perform the switching of the capacitance switching power conversion The switch, from a viewpoint, the part of the plurality of switching switches, in the second regulation mode, is used to turn on and turn off the capacitor for at least a period of time at least in each switching period. In other words, none of the plurality of switches described above are dedicated to short-circuit conduction.

Please continue to refer to FIG. 4, in one embodiment, the control circuit 207 determines that the inductance-switched power converter 205 operates in the first regulation mode or the first short-circuit conduction mode according to at least one of the parameters of the DC power supply and the charging power supply, and/or Or control the capacitor-switched power converter 206 to operate in the second regulation mode or the second short-circuit conduction mode. In one embodiment, the parameters of the DC power supply and the charging power supply can be, for example, but not limited to, at least one of the DC voltage VBUS, the DC current IBUS, the charging voltage VCH, and the charging current ICH. The circuit 207 determines the combination of the above-mentioned operation modes of the inductance-switched power converter 205 and the capacitance-switched power converter 206 according to the relationship between the parameter and at least one threshold. Alternatively, in another embodiment, the control circuit 207 determines the inductance switching according to the relationship between at least two of the DC voltage VBUS, the DC current IBUS, the charging voltage VCH, and the charging current ICH, such as but not limited to the magnitude or the ratio. The power converter 205 and the capacitance-switched power converter 206 are a combination of the above operating modes. More specific examples will be described in detail later.

Please continue to refer to FIG. 4 , in one embodiment, the inductive switching power converter may correspond to, for example, the step-down switching power converter (corresponding to 205 ) in the embodiment of FIG. 4 , or may be as shown in FIG. 6A . The buck-boost switching power converter (corresponding to 208 ), or the step-up switching power converter (corresponding to 209 ) shown in FIG. 6B . From one point of view, the inductive switching power converter can also be other inductive switching power supply architectures, as long as it can short-circuit its input and output (ie, the DC power supply and the The function of the first power supply) can be applied to the present invention.

Please continue to refer to FIG. 4 , in an embodiment, in the first short-circuit conduction mode, the control circuit 207 controls the upper bridge switch M11 to be in constant conduction. In one embodiment, in the first short-circuit conduction mode, the control circuit 207 controls the lower bridge switch M12 to be non-conductive at all times. In another embodiment, the lower bridge switching element can also be, for example, a diode. It should be noted that, from a point of view, in the first short-circuit conduction mode, the short-circuit conduction paths of the DC power supply and the first power supply simultaneously include the constant conduction high-bridge switch M11 and the inductor L.

Please continue to refer to FIG. 6A , in this embodiment, in the first short-circuit conduction mode, the input high-bridge switch M13 and the output high-bridge switch M15 are controlled to be in constant conduction, and the input low-bridge switch M14 and the output low-bridge switch M16 Control is always non-conductive.

Please continue to refer to FIG. 6B , in this embodiment, in 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.

On the other hand, please continue to refer to FIG. 4 , in a specific embodiment, in the second short-circuit conduction mode, the control circuit 207 controls the switches M21 and M22 to be constantly conducting, and controls the switch M24 to be constantly non-conducting . In one embodiment, in the second short-circuit conduction mode, the switch M23 can be either non-conductive or conductive.

It should be noted that, in the following embodiments, the step-down inductor-switching power converter and the voltage-dividing capacitor-switching power converter as shown in the embodiment of FIG. category.

FIG. 7 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein (charging system 1007 and power conversion circuit 200 ) according to the present invention. This embodiment is based on the embodiment shown in FIG. 4 . In this embodiment, the DC voltage VBUS sent by the power transmission unit 100 is, for example, 9V, and the DC current IBUS can output, for example, up to 2.3A. In other words, in this embodiment, the power supply sends The maximum power that the unit 100 can output is about 21W. In addition, 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 the charging current ICH (corresponding to the battery current IBAT) to charge the battery 300 . The capacitor-switched power converter 206 operates in the second regulation mode. Under the condition that the aforementioned current amplification factor k is 2, the first voltage V1 (twice the charging voltage VCH) will be 7V. In this case, the DC voltage The difference between VBUS and the first voltage V1 is still greater than 0, and the condition that the capacitor-switched power converter 206 can operate in the second regulation mode is established. In one embodiment, the control circuit 207 may determine that the inductance-switched power converter 205 operates in the first regulation mode, and the capacitance-switched power converter 206 operates in the second regulation mode. In this case, the battery 300 can be charged with maximum power. Specifically, in this embodiment, in the first regulation mode, the DC voltage VBUS is 9V, the DC current can output up to 2.3A, the first voltage V1 is 7V, the first current I1 can reach 3A, and in the second regulation In the mode, the charging voltage VCH is 3.5V, and the charging current ICH can reach 6A.

FIG. 8 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein (charging system 1008 and power conversion circuit 200 ) according to the present invention. This embodiment is based on the embodiment shown in FIG. 4 . In this embodiment, the DC voltage VBUS sent by the power transmitting unit 100 can reach, for example, 9V, and the DC current IBUS can output, for example, 2A. In other words, in this embodiment, the power sending The maximum power that the unit 100 can output can be up to 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 the charging current ICH to charge the battery 300 . In addition, if the capacitor-switching power converter 206 is controlled to operate in the first In the second adjustment mode, under the condition that 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 Still greater than 0, the condition for the capacitance-switched power converter 206 to be operable in the second regulation mode is established.

In one embodiment, as shown in FIG. 8 , the control circuit 207 may determine that the inductance-switching power converter 205 operates in the first short-circuit conduction mode (the thick solid line indicates that M11 is constantly conducting, and the blank indicates that M12 is constantly non-conducting), and The capacitance-switched power converter 206 operates in the second regulation mode. Specifically, in this embodiment, the power transmitting unit 100 provides the maximum constant current, that is, the DC current IBUS is 2A, the inductance switching power converter 205 operates in the first short-circuit conduction mode, the first current I1 is also 2A, and The capacitor switching power converter 206 operates in the second regulation mode, the charging current ICH is 4A, and the DC voltage VBUS and the first voltage V1 are both equal to 7V.

It should be noted that, in this case, since the inductive 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 corresponds to a mobile power supply, the battery life of the power transmitting unit 100 itself can be extended in particular. The conversion circuit 200 can thus also reduce the operating temperature.

In addition, in another embodiment, the inductance-switched power converter 205 has a maximum duty cycle Dmax. When the relationship between the DC voltage VBUS and the first voltage V1 makes the inductance-switched power converter 205 operate in the first regulation mode, The maximum duty cycle Dmax may be exceeded. In this case, it is also determined that the inductance-switched power converter 205 operates in the first short-circuit conduction mode.

9 shows a schematic diagram (charging system 1009 and power conversion circuit 200 ) of an embodiment of a high-efficiency charging system and a power conversion circuit therein according to the present invention. This embodiment is based on the embodiment shown in FIG. 4 . In this embodiment, the DC voltage VBUS sent by the power sending unit 100 is, for example, 5V, and the DC current IBUS can output, for example, 2.1A. In other words, in this embodiment, the power sending The maximum power that the unit 100 can output 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 the charging current ICH to charge the battery 300 . In addition, if the capacitor-switching power converter 206 is controlled to operate in the first In the second adjustment mode, under the condition that 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 capacitance-switched power converter 206 to operate in the second regulation mode does not hold.

Therefore, in one embodiment, as shown in FIG. 9 , the control circuit 207 may determine that the inductance-switching power converter 205 operates in the first regulation mode, and the capacitor-switching power converter 206 operates in the second short-circuit conduction mode (in rough terms). Lines indicate that M21 and M22 are always on, and blanks indicate that M23 and M24 are always off). In this case, the battery 300 can be charged with maximum power. Specifically, in this embodiment, the DC voltage VBUS is powered by 5V, the inductance switching power converter 205 operates in the first regulation mode, the first current I1 is adjusted to 3A, and the capacitance switching power converter 206 operates in the second regulation mode. In the short-circuit conduction mode, the first voltage V1 is the same as the battery voltage VBAT, both being 3.5V. In this case, the DC current IBUS corresponds to 2.1A, that is, the battery 300 is charged with the maximum power in this embodiment.

FIG. 10 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein (charging system 1010 and power conversion circuit 200 ) according to the present invention. This embodiment is based on the embodiment shown in FIG. 4 . In this embodiment, the DC voltage VBUS sent by the power supply transmitting unit 100 can output, for example, up to 5V, and the DC current IBUS can output, for example, up to 2A. In other words, in this embodiment, the power supply The maximum power that the sending unit 100 can output can reach 10W. In this embodiment, the voltage condition of the power transmission unit 100 is similar to that of the embodiment of FIG. 9 , that is, the condition that the capacitor-switched power converter 206 operates in the second regulation mode does not hold.

Therefore, in one embodiment, as shown in FIG. 10 , the control circuit 207 can determine that the inductive switching power converter 205 operates in the first short-circuit conduction mode, and the capacitance-switching power converter 206 operates in the second short-circuit conduction mode, and the control circuit 207 may request the power transmission 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, and in the first short-circuit conduction mode and the second short-circuit conduction mode, the first current I1 and the charging current ICH are also 2A at the same time, and The first voltage V1 and the DC voltage VBUS are both equal to 3.5V, that is, corresponding to the battery voltage VBAT. In other words, the charging system 1010 operates in the direct charging mode, and the battery 300 is directly charged with a constant current by the power transmitting unit 100 .

11 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein (charging system 1011 and power conversion circuit 200') according to the present invention. This embodiment is based on the embodiment shown in FIG. 4 . In this embodiment, the power transmission unit 100 , for example, optionally in a low power mode, the transmitted DC voltage VBUS can output up to 5V, and the corresponding DC current IBUS such as The output can be up to 2A, in other words, in this embodiment, in this mode, the maximum power that the power transmitting unit 100 can output can be up to 10W. In a high power mode, the transmitted DC voltage VBUS can output up to 9V, and the corresponding DC current IBUS can output up to 2A, for example. In other words, in this embodiment, in the high power mode, the power transmission unit 100 can output The maximum output power 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 the charging current ICH to charge the battery 300 . In addition, if the capacitor-switching power converter 206 is controlled to operate in the first In the second regulation mode, under the condition that 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 needs to be greater than or equal to 7V.

Therefore, in this embodiment, as shown in FIG. 11 , optionally, the control circuit 207 determines that the inductance-switching power converter 205 operates in the first short-circuit conduction mode, and the capacitance-switching power converter 206 operates in the second regulation mode, In addition, the control circuit 207 can request the power transmitting unit 100 to output a constant current and operate in a high power mode through the aforementioned communication interface CB. Specifically, in this embodiment, the DC current IBUS of the power transmitting unit 100 is adjusted to 2A, and in the first short-circuit conduction mode and the second adjustment mode, the first current I1 and the charging current ICH are respectively 2A and 4A, and The first voltage V1 and the DC voltage VBUS are both equal to 7V, that is, corresponding to twice the battery voltage VBAT.

From one point of view, according to the description of the foregoing embodiments, it can be concluded that the control circuit 207 determines whether the inductive switching power converter 205 operates in the first short-circuit conduction mode, or determines whether the capacitor-switching power converter 206 operates in the second short-circuit conduction mode. The timing principle is detailed below.

In one embodiment, when the DC voltage VBUS of the DC power source is lower than the first threshold Vth1, the inductively switched power converter 205 operates in the first short-circuit conduction mode. In one embodiment, the first threshold Vth1 is related to the first voltage V1. When the capacitor-switched power converter 206 operates in the 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. In addition, when the capacitor-switched power converter 206 operates in the 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.

For example, assuming that the maximum duty cycle of the inductance-switched power converter 205 in the first regulation mode is Dmax, in the embodiment in which the capacitance-switched power converter 206 operates in the second regulation mode, the first threshold Vth1 can be set as follows The formula yields:

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

In addition, when the power sending unit 100 can send a constant DC current IBUS, as shown in the embodiment of FIG. 8 or FIG. 10 , optionally, the inductance switching power converter 205 can be controlled to operate in the first short-circuit conduction mode, such as As mentioned above, the power conversion efficiency of the charging system can be improved.

From another perspective, in one embodiment, when the power sending unit 100 can send a constant DC current IBUS, and the DC voltage VBUS is variable and can exceed VBAT*k, optionally, the inductor can be controlled to switch the power supply The converter 205 operates in the first short-circuit conduction mode, and simultaneously controls the capacitor-switched power converter 206 to operate in the second regulation mode.

On the other hand, when the DC voltage VBUS of the DC power source is lower than the second threshold Vth2, the capacitor-switched power converter 206 operates in the second short-circuit conduction mode, wherein 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 With respect to k*VBAT; specifically, in a preferred embodiment, Vth2≧k*VBAT.

In addition, in general, since the maximum duty cycle Dmax is usually less than 1, when the inductive 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.

9 and 10 , when the DC voltage VBUS voltage is too low to satisfy the condition that the capacitor switching power converter 206 operates in the second regulation mode, in this case, the control circuit 207 can determine the control capacitor The switching power converter 206 operates in the second short-circuit conduction mode.

To sum up, in one embodiment, when the inductance switching power converter 205 corresponds to a step-down switching power converter, and the DC voltage VBUS is programmable and is lower than the first threshold Vth1, the plurality of switching elements The upper bridge switch in the circuit is completely turned on to short-circuit the first power supply and the charging power supply.

In one embodiment, when the DC voltage VBUS is lower than the second threshold Vth2, some of the switches in the plurality of switching switches are completely turned on to short-circuit the first power source and the charging power source.

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

In addition, according to the combination of the aforementioned various operation modes, in one embodiment, the control circuit 207 can be used to control the DC voltage VBUS of the DC power supply 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 .

12 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein according to the present invention (charging system 1012 and power conversion circuit 200 ″). This embodiment is similar to the previous embodiment. 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 capacitance switching power converter 206" is used to switch the switching capacitor CF. In one embodiment, the inductance switching power converter 205", the capacitance switching power converter 206" and the control circuit 207 are integrated into an integrated circuit, that is, the power conversion circuit 200" corresponds to the integrated circuit.

As mentioned above, the embodiments of FIGS. 4 to 5 and FIGS. 7 to 12 all use a step-down inductor-switched power converter and a voltage-divider capacitor-switched power converter to demonstrate the operation of the present invention. In other implementations In an example, the relationship between the above-mentioned multiple k and the threshold value can be adjusted correspondingly according to the combination of the actual power converters. Those skilled in the art can make their own inferences based on the spirit of the present invention, which will not be repeated here.

The invention provides a power conversion circuit composed of an inductance switching power converter and a capacitance switching power converter connected in series, which can adaptively select the inductance switching power converter and the capacitor according to the requirements of DC power supply, battery voltage and state, etc. Switching the combination of operating modes of the power converter to the maximum power or high efficiency mode, or to make the power conversion circuit operate at a maximum efficiency operating point to charge the battery.

The present invention has been described above with respect to the preferred embodiments, but the above descriptions are only intended to make the content of the present invention easy for those skilled in the art to understand, and are not intended to limit the broadest scope of rights of the present invention. The described embodiments are not limited to be used alone, but can also be used in combination. For example, two or more embodiments can be used in combination, and some components in one embodiment can also be used to replace those in another embodiment. corresponding components. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. According to the signal itself, when necessary, the signal is subjected to voltage-to-current conversion, current-to-voltage conversion, and/or ratio conversion, etc., and then processed or calculated according to the converted signal to generate an output result. It can be seen from this that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed and described here. Accordingly, the scope of the present invention should cover the above and all other equivalent changes.

100, 100’: Power Transmitter Unit 1004, 1005, 1007~1012: Charging system 1001: Inductive Switching Power Converters 1002: Capacitor Switching Power Converters 1003: Load Switch Circuits 200, 200’, 200”: power conversion circuit 205, 205”: Inductive Switching Power Converters 206, 206”: Capacitor Switching Power Converters 207, 207’: Control circuit 208: Buck-Boost Switching Power Converters 209: Boost Switching Power Converters 300: battery 400: Cable Wire CB: Communication Interface CF: Conversion capacitor ct1, ct2: control signal Dmax: maximum duty cycle I1: first current IBAT: battery current IBUS: DC current ICH: charging current k: current magnification L: Inductance M11: High Bridge Switch M12: lower bridge switch M21, M22, M23, M24: toggle switch PH1, PH2: charging transition period V1: first voltage VCH: charging voltage VBAT: battery voltage VBUS: DC voltage Vth1, Vth2: Threshold

FIG. 1 shows a schematic circuit diagram of an inductive switching power converter of the prior art.

FIG. 2 shows a schematic circuit diagram of a capacitor-switched power converter of the prior art.

FIG. 3 shows a schematic circuit diagram of another prior art load switch circuit.

FIG. 4 shows a schematic diagram of an embodiment of the high-efficiency charging system and the power conversion circuit therein of the present invention.

FIG. 5 is a schematic diagram showing another embodiment of the high-efficiency charging system of the present invention and the power conversion circuit therein.

FIG. 6A shows a schematic diagram of an embodiment of an inductively switched power converter according to the present invention.

FIG. 6B shows a schematic diagram of an embodiment of an inductively switched power converter according to the present invention.

FIG. 7 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein of the present invention.

FIG. 8 shows a schematic diagram of an embodiment of the high-efficiency charging system and the power conversion circuit therein of the present invention.

FIG. 9 shows a schematic diagram of an embodiment of the high-efficiency charging system and the power conversion circuit therein of the present invention.

FIG. 10 is a schematic diagram showing an embodiment of a high-efficiency charging system and a power conversion circuit therein of the present invention.

FIG. 11 shows a schematic diagram of an embodiment of the high-efficiency charging system and the power conversion circuit therein of the present invention.

FIG. 12 shows a schematic diagram of an embodiment of a high-efficiency charging system and a power conversion circuit therein of the present invention.

100: Power sending unit 1004: Charging System 200: Power Conversion Circuit 205: Inductive Switching Power Converters 206: Capacitor Switching Power Converters 207: Control circuit 300: battery 400: Cable Wire CF: Conversion capacitor ct1, ct2: control signal I1: first current IBAT: battery current IBUS: DC current ICH: charging current L: Inductance M11: High Bridge Switch M12: lower bridge switch M21, M22, M23, M24: toggle switch PH1, PH2: charging transition period V1: first voltage VCH: charging voltage VBAT: battery voltage VBUS: DC voltage Vs: input power

Claims (13)

A power conversion circuit, comprising: an inductance switching power converter, including a plurality of switching elements, the plurality of switching elements are used to switch the coupling relationship between an inductance, a DC power supply and a first power supply, so as to convert the DC power supply to generate the a first power supply; and a capacitor switching power converter, including a plurality of switching switches, the plurality of switching switches are used to switch the coupling relationship between a switching capacitor, the first power supply and a charging power supply, so as to convert the first power supply to generate the a charging power supply; wherein the inductance switching power converter has a first regulation mode and a first short-circuit conduction mode, and in the first regulation mode, a plurality of the switching elements switch the inductance to regulate the first power supply to a first preset The objective is that in the first short-circuit conduction mode, the corresponding at least one switching element is controlled to be turned on, so as to short-circuit the DC power supply to the first power supply; wherein the capacitance-switching power converter has a second regulation mode and a second short-circuit conduction mode, in the second adjustment mode, a plurality of the switch switches switch the conversion capacitor to adjust the charging power source to a second preset target, in the second short-circuit conduction mode, corresponding to at least one of the switch control In order to conduct, the first power supply is short-circuited to the charging power supply; wherein, the power conversion circuit determines that the inductance switching power converter operates in the first regulation mode or the first short-circuit conduction mode according to a parameter of the DC power supply , and/or determine that the capacitor-switched power converter operates in the second regulation mode or the second short-circuit conduction mode. The power conversion circuit according to claim 1, characterized in that: When a DC voltage of the DC power source is lower than a first threshold value, the inductive switching power converter operates in the first short-circuit conduction mode, wherein the first threshold value is related to a charging voltage of the charging power source; or when the DC voltage is low At a second threshold, the capacitor-switched power converter operates in the second short-circuit conduction mode, wherein the second threshold is related to the product of the charging voltage and a current amplification ratio, wherein the current amplification ratio is a ratio of the charging power supply. A ratio of a charging current to a first current of the first power source; or when a DC current of the DC power source is constant, the inductance-switched power converter operates in the first short-circuit conduction mode; or when the DC power source is in a constant state When the DC current is constant and the DC voltage is variable and can exceed the second threshold, the inductance switching power converter operates in the first short-circuit conduction mode, and the capacitance switching power converter operates in the second regulation model. The power conversion circuit of claim 1, wherein the inductance switching power converter corresponds to a buck switching power converter or a buck-boost switching power converter. The power conversion circuit of claim 1, wherein the DC power is provided by an AC-DC (AD-DC) converter. The power conversion circuit of claim 1, wherein the capacitor-switched power converter corresponds to a voltage-dividing capacitor-switched power converter. The power conversion circuit of claim 4, wherein a charging voltage of the charging power source is 1/2 or 1/4 of a first voltage of the first power source, and a charging current of the charging power source is correspondingly the 2 times or 4 times the first current of one of the first power sources. The power conversion circuit of claim 2, wherein when the inductance switching power converter corresponds to a step-down switching power converter, and the DC voltage is programmable and is lower than the first threshold, the An upper-bridge switch in the plurality of switching elements is fully turned on, so as to short-circuit the DC power supply and the first power supply. The power conversion circuit of claim 2, wherein when the DC voltage is lower than the second threshold, some switches in the plurality of switches are completely turned on to short-circuit the first power source and the charging power source. The power conversion circuit of claim 4, wherein the AC-DC converter is a power adapter conforming to the Universal Serial Bus Power Delivery Protocol (USB PD). The power conversion circuit of claim 1, further comprising a control circuit for controlling the DC voltage of the DC power supply and/or a DC current of the DC power supply through a communication interface. The power conversion circuit of claim 10, wherein the communication interface corresponds to D+ and D- signals of Universal Serial Bus Protocol (USB), or corresponds to CC1 and CC2 of Universal Serial Bus Power Delivery Protocol (USB PD). signal. The power conversion circuit of claim 1, further comprising a control circuit for controlling the DC voltage of the DC power supply and/or a DC current of the DC power supply, so that the power conversion circuit operates at a maximum efficiency operating point . A charging system for converting an input power to generate a charging power, the charging system comprising: a power sending unit for converting the input power to generate a DC power; and The power conversion circuit according to any one of claims 1 to 12 is used to convert the DC power to generate the charging power.

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