Power supply system with power factor correction and control method thereof

Abstract

The invention discloses a power supply system with power factor correction and a control method thereof. A power supply system with power factor correction comprises an alternating current rectifier, a power factor correction conversion circuit, a direct current-direct current converter, a communication protocol power supply transmission interface and a controller. The AC rectifier is used for rectifying an AC input power supply to generate a rectified power supply. The power factor correction conversion circuit is used for performing power factor correction conversion on the rectification power supply to generate a conversion power supply. The DC-DC converter is used for DC-DC conversion of a conversion power supply to generate an adapter output power supply. The communication protocol power supply transmission interface is used for determining an adapter output power supply according to the communication protocol information and controlling a power supply path switch so as to transmit the adapter output power supply to a power supply pin. The controller is used for determining the conversion voltage according to the rectified voltage and the adapter output voltage.

Description

Technical Field

[0001] The present invention relates to a power supply system with power factor correction, and particularly to a power supply system in which the conversion voltage is related to the rectified voltage and the adapter output voltage. The present invention also relates to a power supply system control method for controlling the above power supply system. Background Art

[0002] Please refer to Figure 1A , Figure 1A which is a schematic diagram of a prior art power supply system 100. As Figure 1A shown, the prior art power supply system 100 includes an AC rectifier 1, a power factor correction (PFC) conversion circuit 10, a flyback power converter 15, and a communication protocol (protocol) power delivery (PD) interface 40. The AC rectifier 1 rectifies the AC input voltage VAC to generate a rectified voltage VBD, and the power factor correction conversion circuit 10 is used to perform power factor correction conversion to convert the rectified voltage VBD to generate a power factor correction conversion voltage VPFC. The power factor correction conversion circuit 100 includes a boost power stage circuit, and boosts the rectified voltage VBD to convert it into the PFC conversion voltage VPFC, where the power factor correction conversion circuit 100 is used to correct the power factor of the power supply system 100.

[0003] Please refer to Figure 1B , Figure 1B which is a waveform diagram of the rectified voltage VBD and the PFC conversion voltage VPFC in a prior art power supply system. As Figure 1B shown, after rectification by the AC rectifier 1, the waveform of the rectified voltage VBD is a full wave rectified sine wave above zero, and after the power factor correction conversion circuit 10 performs PFC conversion to generate a DC PFC conversion voltage VPFC, where the PFC conversion voltage VPFC is usually a fixed value higher than the peak value of the rectified voltage VBD.

[0004] The flyback power converter 15 is used to convert the PFC conversion voltage VPFC in a DC-DC manner to generate the adapter output voltage VDD, and supply power to the communication protocol PD interface 40. The communication protocol PD interface 40 is used to transmit relevant information to the DC-DC power converter 15 according to the communication protocol information PRT1, and determine the adapter output voltage VDD. The communication protocol PD interface 40 also controls the power path switch MBUS therein to transmit the adapter output voltage VDD to the power supply pin VBUS therein, and then supply the adapter output voltage VDD to an externally coupled circuit (not shown). The aforementioned power supply system 100 is often used in traditional traveler adaptors with relatively fixed output power and output voltage.

[0005] Traveler adaptors compliant with the latest universal serial bus power delivery (USB PD) specification need to provide output power ranging from 5V / 5A (i.e., 25W) to 20V / 5A (i.e., 100W). According to the USB PD extended power range (EPR) protocol, the maximum output power can reach 48V / 5A (i.e., 240W). According to the IEC61000-3-2 standard, electrical appliances (devices compliant with Class-D) with an input power of 75W or more must comply with the maximum amplitude limit regulations of line-frequency harmonics of up to 39th harmonic. Therefore, a USB PD traveler adaptor with an output power of not less than 75W should have a Figure 1A power supply system 100 including a power factor correction (PFC) conversion circuit 10 as shown to minimize line-frequency harmonics. For the application of USB PD EPR traveler adaptors, it is necessary to generate a PFC conversion voltage VPFC level of, for example, 400V for a general universal AC input voltage VAC range, such as from 85 to 265Vrms, and the adapter output voltage VDD range is, for example, from 5V to 48V, and the adapter output current IDD range is, for example, from 0.5A to 5V. From the above specifications, it can be seen that the output power of current USB PD EPR traveler adaptor applications is very wide.

[0006] One of the disadvantages of implementing a USB PD EPR travel adapter using the above prior art power supply system 100 is that, for example, on the premise that the voltage level of the conversion voltage VPFC is fixed at 400V, in applications where the rectified voltage VBD is relatively low (such as 85Vrms), and / or the output voltage VDD of the adapter (such as below 20V) or the output power of the power supply is relatively low, the energy loss of the power supply system 100 is relatively high, resulting in a relatively low conversion efficiency.

[0007] In addition, when the flyback power converter 15 converts the PFC conversion voltage VPFC into the adapter output voltage VDD, the traditional flyback power converter 15 is not easy to achieve zero voltage switching (ZVS), and there will be a relatively high voltage stress, resulting in a relatively low conversion efficiency and a relatively high cost.

[0008] For other related prior arts, please refer to U.S. Patent No. US 11411489 and U.S. Patent No. US6768655.

[0009] In view of this, the present invention aims at the deficiencies of the above prior art and proposes a power supply system and its control method in which the conversion voltage is related to the rectified voltage and the adapter output voltage. Since the present invention can determine whether to prohibit power factor correction conversion according to the adapter output power, the energy loss can be reduced and the conversion efficiency can be improved. Summary of the Invention

[0010] The present invention provides a power supply system with power factor correction, including: an AC rectifier for rectifying an AC input power supply to generate a rectified power supply, where the rectified power supply includes a rectified voltage; a power factor correction (PFC) conversion circuit for performing a PFC conversion on the rectified power supply to generate a converted power supply, where the converted power supply includes a conversion voltage; a DC-DC converter for performing DC-DC conversion on the converted power supply to generate an adapter output power supply, where the adapter output power supply includes an adapter output voltage and an adapter output current; a communication protocol (protocol) power delivery (PD) interface for determining the adapter output power supply according to a communication protocol information and controlling one of the power path switches to transmit the adapter output power supply to one of the power supply pins; and a controller for determining the conversion voltage according to the rectified voltage and the adapter output voltage.

[0011] The present invention also provides a method for controlling a power supply system, including: rectifying an AC input power supply to generate a rectified power supply, where the rectified power supply includes a rectified voltage; performing a power factor correction (PFC) conversion on the rectified power supply to generate a converted power supply, where the converted power supply includes a converted voltage; performing a DC-DC conversion on the converted power supply to generate an adapter output power supply, where the adapter output power supply includes an adapter output voltage and an adapter output current; determining the adapter output power supply according to a communication protocol information, and controlling a power path switch to transmit the adapter output power supply to a power supply pin; and determining the converted voltage according to the rectified voltage and the adapter output voltage.

[0012] In an embodiment, when the adapter output voltage decreases, the controller correspondingly decreases the converted voltage.

[0013] In an embodiment, when the adapter output voltage is higher than an enabling threshold, the controller enables the PFC conversion circuit to perform the PFC conversion, and when the adapter output voltage is lower than a disabling threshold, the controller prohibits the PFC conversion circuit from performing the PFC conversion.

[0014] In an embodiment, the controller adjusts the converted voltage linearly according to the adapter output voltage.

[0015] In an embodiment, the controller also adjusts the converted voltage related to the adapter output current.

[0016] In an embodiment, the DC-DC converter is a flyback converter, an LLC converter or an active clamp forward converter.

[0017] In an embodiment, the flyback converter includes an asymmetric half-bridge (AHB) flyback converter.

[0018] In an embodiment, the controller adjusts the converted voltage according to the rectified voltage, the adapter output voltage and the adapter output current to optimize a conversion efficiency between the rectified voltage and the adapter output voltage.

[0019] In an embodiment, in the power supply system with power factor correction, the controller uses the rectified voltage and the adapter output voltage as inputs of a predetermined algorithm to determine the converted voltage to achieve a relatively better conversion efficiency.

[0020] In one embodiment, the predetermined algorithm includes a look-up table method, and the controller selects relatively better operating parameters from a pre-stored data table according to different rectified voltages, adapter output voltages, and adapter output currents to adjust the conversion voltage.

[0021] The following will be described in detail through specific embodiments to more easily understand the purpose, technical content, features, and achieved effects of the present invention. Brief Description of the Drawings

[0022] Figure 1A is a schematic diagram of a prior art power supply system.

[0023] Figure 1B is a waveform diagram of input voltage and output voltage in a prior art power supply system.

[0024] Figure 2 shows an embodiment of a power supply system with power factor correction according to the present invention.

[0025] Figure 3A 、 Figure 3B and Figure 3C shows the relationship between the adapter output voltage VDD, conversion voltage VCN, adapter output current IDD, rectified voltage VBD, and conversion efficiency Nu.

[0026] Figure 4 is a flowchart of an embodiment of the power factor correction conversion circuit in the power supply system of the present invention.

[0027] Symbol Description in the Figures

[0028] 1: AC rectifier

[0029] 10, 20: PFC conversion circuit

[0030] 15: Flyback power converter

[0031] 30: DC-DC converter

[0032] 40: Communication protocol PD interface

[0033] 100, 200: Power supply system

[0034] DTM: Decision signal

[0035] IDD, IDD1, IDD2, IDD3, IDD4: Adapter output current

[0036] MBUS: Power path switch

[0037] Nu, Nu, Nu2, Nu3, Nu4, Nu5, Nu6, Nu7: Conversion efficiency

[0038] PRT1: Communication protocol information

[0039] S11, S12, S13, S14, S15, S16: Steps

[0040] SWb: Bypass switch

[0041] VAC: AC input voltage

[0042] VBD: Rectified voltage

[0043] VBUS: Power supply pin

[0044] VCN, VCN1, VCN2, VCN3: Conversion voltage

[0045] VDD, VDD1, VDD2, VDD3: Adapter output voltage

[0046] VPFC: Power factor correction conversion voltage Detailed implementation manners

[0047] The drawings in the present invention are all schematic, mainly intended to show the coupling relationships between various circuits and the relationships between various signal waveforms. As for the circuits, signal waveforms and frequencies, they are not drawn according to scale. For the sake of clear explanation, many practical details will be described together in the following description, but this is not intended to limit the scope of the patent application of the present invention.

[0048] Please refer to Figure 2 , Figure 2 , showing an embodiment of the power supply system with power factor correction of the present invention. As Figure 2 shown, in one embodiment, the power supply system 200 with power factor correction includes: an AC rectifier 1, a power factor correction (PFC) conversion circuit 20, a DC-DC converter 30, a communication protocol (protocol) power delivery (PD) interface 40, and a controller 50. In one embodiment, the AC rectifier 1 is used to rectify the AC input power to generate a rectified power. Among them, the AC input power includes the AC input voltage VAC, and the rectified power includes the rectified voltage VBD. The PFC conversion circuit 20 is used to perform PFC conversion on the rectified power to generate a conversion power. Among them, the conversion power includes the conversion voltage VCN. The DC-DC converter 30 converts the conversion power in a DC-DC manner to generate an adapter output power. Among them, the adapter output power includes the adapter output voltage VDD and the adapter output current IDD.

[0049] As Figure 2As shown, the communication protocol PD interface 40 is used to transmit relevant information to the DC-DC converter 30 based on the communication protocol information PRT1 to determine the adapter output power. The communication protocol PD interface 40 controls the power path switch MBUS therein to transmit the adapter output power to the power supply pin VBUS therein, thereby supplying the adapter output power to an externally coupled circuit (not shown). The controller 50 generates a determination signal DTM based on the rectified voltage VBD and the adapter output voltage VDD, which is input to the PFC converter circuit 20 to determine the conversion voltage VCN. The conversion voltage VCN is correlated with the rectified voltage VBD and the adapter output voltage VDD.

[0050] In conventional power supply systems, the conversion voltage VCN is adjusted to a fixed level, such as 400V, corresponding to varying AC input voltages VAC, such as 85Vrms to 265Vrms, varying adapter output voltages VDD, such as 5V to 48V, and varying adapter output currents, such as 0.5A to 5A. This causes the conversion efficiency of conventional power supply systems to vary significantly under different conditions, resulting in poor overall conversion efficiency. One feature that distinguishes the present invention from the conventional technology is that, according to the present invention, the controller 50 determines the conversion voltage VCN based on the rectified voltage VBD and the adapter output voltage VDD to improve conversion efficiency. In one embodiment, the controller 50 further adjusts the conversion voltage VCN based on the adapter output current IDD to improve conversion efficiency. According to the present invention, the conversion voltage VCN can be adjusted, or the PFC conversion can be enabled / disabled, by comprehensively considering the rectified voltage VBD, the adapter output voltage VDD, and the adapter output current IDD to improve conversion efficiency Nu.

[0051] Figure 3A 、 Figure 3B and Figure 3CSeparate displays show the conversion efficiency Nu between the rectified voltage VBD and the adapter output voltage VDD corresponding to different adapter output currents IDD at different conversion voltages VCN or when PFC conversion is prohibited, when the adapter output voltage VDD is the adapter output voltage VDD1, the adapter output voltage VDD2, and the adapter output voltage VDD3. Among them, in one embodiment, the adapter output voltage VDD1 is higher than the adapter output voltage VDD2, and the adapter output voltage VDD2 is higher than the adapter output voltage VDD3; the conversion voltage VCN1 is higher than the conversion voltage VCN2; the adapter output current IDD1 is lower than the adapter output current IDD2, the adapter output current IDD2 is lower than the adapter output current IDD3, the adapter output current IDD3 is lower than the adapter output current IDD4; and the conversion efficiency Nu1 is higher than the conversion efficiency Nu2, the conversion efficiency Nu2 is higher than the conversion efficiency Nu3, the conversion efficiency Nu3 is higher than the conversion efficiency Nu4, the conversion efficiency Nu4 is higher than the conversion efficiency Nu5, the conversion efficiency Nu5 is higher than the conversion efficiency Nu6, and the conversion efficiency Nu6 is higher than the conversion efficiency Nu7. Among them, in one embodiment, the adapter output currents IDD1 to IDD4 increase in sequence in a linear manner or in an arithmetic progression. Among them, in one embodiment, the conversion efficiencies Nu1 to Nu7 decrease in an arithmetic progression.

[0052] In one embodiment, according to the present invention, when the adapter output voltage VDD decreases, the controller 50 generates a corresponding change in the decision signal DTM, so that the PFC conversion circuit 20 determines to correspondingly decrease the conversion voltage VCN according to the decision signal DTM.

[0053] For example, refer to Figure 3A and Figure 3B , when the adapter output voltage VDD1 decreases to the adapter output voltage VDD2, and the adapter output currents IDD are all maintained at the adapter output current IDD3, the controller 50 generates a corresponding change in the decision signal DTM, so that the PFC conversion circuit 20 determines to correspondingly decrease the conversion voltage VCN from the conversion voltage VCN1 to the conversion voltage VCN3 according to the decision signal DTM, so as to obtain a higher conversion efficiency Nu.

[0054] In one embodiment, when the adapter output voltage VDD is higher than an enabling threshold, the controller 50 adjusts the decision signal DTM to enable PFC conversion, and when the adapter output voltage VDD is lower than a prohibiting threshold, the controller 50 adjusts the decision signal DTM to prohibit PFC conversion.

[0055] For example, refer to Figure 3A , Figure 3B and Figure 3C , the adapter output voltage VDD is the adapter output voltage VDD2 (Figure 3B ), when the adapter output current IDD is maintained at the adapter output current IDD1 or IDD2, deciding to prohibit PFC conversion (PFC OFF) can obtain a higher conversion efficiency Nu; and when the adapter output voltage VDD changes from the adapter output voltage VDD2 ( Figure 3B ) to the adapter output voltage VDD1 ( Figure 3A ), adjusting the decision signal DTM to enable PFC conversion and deciding that the conversion voltage VCN is the conversion voltage VCN2 can obtain a higher conversion efficiency Nu. Therefore, when the adapter output current is IDD1 or IDD2, the enable threshold is between the adapter output voltage VDD1 and the adapter output voltage VDD2. On the other hand, when the adapter output voltage VDD changes from the adapter output voltage VDD1 ( Figure 3A ) to the adapter output voltage VDD2 ( Figure 3B ), when the adapter output current IDD is maintained at the adapter output current IDD1 or IDD2, deciding to change from enabling PFC conversion to prohibiting PFC conversion, and the disable threshold is also between the adapter output voltage VDD1 and the adapter output voltage VDD2. The enable threshold and the disable threshold can be the same value or different values.

[0056] In one embodiment, the controller 50 adjusts the conversion voltage VCN linearly according to the adapter output voltage VDD. In one of the embodiments, the controller 50 adjusts the conversion voltage VCN to be proportional to the adapter output voltage VDD.

[0057] In one embodiment, the controller 50 also adjusts the conversion voltage VCN related to the adapter output current IDD. For example, referring to Figure 3A , when the adapter output current IDD is the adapter output current IDD1, the controller 50 adjusts the conversion voltage VCN to the adjusted conversion voltage VCN2 to have a higher conversion efficiency Nu; and when the adapter output current is IDD4, the controller 50 adjusts the conversion voltage VCN to the adjusted conversion voltage VCN1 to have a higher conversion efficiency Nu.

[0058] In one embodiment, the DC-DC converter 30 includes, for example but not limited to, a flyback converter, an LLC converter, or an active clamp forward converter. In one of the embodiments, the DC-DC converter 30 includes, for example but not limited to, an asymmetric half-bridge (AHB) flyback converter.

[0059] In one embodiment, the controller 50 adjusts the conversion voltage VCN based on the rectified voltage VBD, the adapter output voltage VDD, and the adapter output current IDD to optimize the conversion efficiency Nu between the rectified voltage VBD and the adapter output voltage VDD.

[0060] For example, the controller 50 uses Figure 3A , Figure 3B and Figure 3C the relationship between the adapter output voltage VDD, the conversion voltage VCN, the adapter output current IDD, the rectified voltage VBD, and the conversion efficiency Nu shown in, to adjust the conversion voltage VCN based on the rectified voltage VBD, the adapter output voltage VDD, and the adapter output current IDD to optimize the conversion efficiency Nu between the rectified voltage VBD and the adapter output voltage VDD.

[0061] In one embodiment, the controller 50 uses the rectified voltage VBD and the adapter output voltage VDD as inputs to a predetermined algorithm to determine the conversion voltage VCN to achieve a relatively better conversion efficiency Nu.

[0062] For example, the controller 50 uses Figure 3A , Figure 3B and Figure 3C the relationship between the adapter output voltage VDD, the conversion voltage VCN, the adapter output current IDD, the rectified voltage VBD, and the conversion efficiency Nu shown in, to design a predetermined algorithm, and uses the rectified voltage VBD, the adapter output voltage VDD, and the adapter output current IDD as inputs to the predetermined algorithm to determine the conversion voltage VCN or adjust the conversion voltage VCN to achieve a relatively better conversion efficiency Nu.

[0063] In one of the embodiments, the predetermined algorithm includes a look-up table method, and the controller 50 selects relatively better operating parameters from a pre-stored data table according to different rectified voltages VBD, adapter output voltages VDD, and adapter output currents IDD to adjust the conversion voltage VCN.

[0064] For example, the controller 50 uses Figure 3A , Figure 3B and Figure 3C the data of the adapter output voltage VDD, the conversion voltage VCN, the adapter output current IDD, the rectified voltage VBD, and the conversion efficiency Nu shown in, to list as a pre-stored data table, and selects relatively better operating parameters from the pre-stored data table according to the values of the rectified voltage VBD, the adapter output voltage VDD, and the adapter output current IDD to determine the conversion voltage VCN or adjust the conversion voltage VCN to achieve a relatively better conversion efficiency Nu.

[0065] According to the present invention, in one embodiment, when the PFC conversion is prohibited, the PFC conversion circuit 20 performs a bypass coupling operation, such that the conversion voltage VCN is equal to the rectified voltage VBD of the rectified power supply.

[0066] Figure 4 An embodiment of the present invention is shown to illustrate an implementation manner of the power supply system control method according to the present invention. As Figure 4 shown, the power supply system control method includes:

[0067] Step S11: Receive an AC voltage.

[0068] Step S12: Rectify the AC input power supply to generate a rectified power supply, where the rectified power supply includes a rectified voltage.

[0069] Step S13: Perform a power factor correction (PFC) conversion on the rectified power supply to generate a converted power supply, where the converted power supply includes a conversion voltage.

[0070] Step S14: Perform a DC-DC conversion on the converted power supply to generate an adapter output power supply, where the adapter output power supply includes an adapter output voltage and an adapter output current.

[0071] Step S15: Determine the adapter output power supply according to a communication protocol information, and control a power path switch to transmit the adapter output power supply to a power supply pin.

[0072] Step S16: Determine the conversion voltage according to the rectified voltage and the adapter output voltage.

[0073] In one embodiment, the step of performing a PFC conversion on the rectified power supply to generate a converted power supply includes: enabling the PFC conversion when the adapter output voltage is higher than an enabling threshold, and prohibiting the PFC conversion when the adapter output voltage is lower than a prohibiting threshold.

[0074] In one embodiment, the power supply system control method further includes: adjusting the conversion voltage according to the rectified voltage, the adapter output voltage, and the adapter output current to optimize a conversion efficiency between the rectified voltage and the adapter output voltage.

[0075] In one embodiment, the power supply system control method further includes: using the rectified voltage and the adapter output voltage as inputs of a predetermined algorithm to determine the conversion voltage to achieve a relatively better conversion efficiency.

[0076] The present invention has been described above with reference to the preferred embodiments. However, as mentioned above, the purpose is only to make it easier for those skilled in the art to understand the content of the present invention, and it is not used to limit the scope of the rights of the present invention. Each of the described embodiments is not limited to being applied alone, and can also be combined. For example, two or more embodiments can be combined, and some components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the present invention's statement of "processing or calculating or generating a certain output result according to a certain signal" is not limited to the signal itself, but also includes, when necessary, converting the signal between voltage and current, current and voltage, and / or ratio conversion, etc., and then processing or calculating according to the converted signal to generate a certain output result. From this, it can be seen 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 combination methods, which are not listed here one by one. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A power supply system with power factor correction, comprising: an AC rectifier for rectifying an AC input power source to generate a rectified power source, wherein the rectified power source includes a rectified voltage; a power factor correction conversion circuit for performing a power factor correction conversion on the rectified power supply to generate a converted power supply, wherein the converted power supply includes a converted voltage; a DC-DC converter for converting the converted power to DC-DC to generate an adapter output power, wherein the adapter output power includes an adapter output voltage and an adapter output current; a communication protocol power transmission interface for determining the adapter output power according to communication protocol information and controlling one of the power path switches to transmit the adapter output power to one of the power supply pins; and A controller is used to determine the conversion voltage according to the rectified voltage and the adapter output voltage.

2. The power supply system with power factor correction as claimed in claim 1, wherein: When the adapter output voltage decreases, the controller correspondingly decreases the conversion voltage.

3. The power supply system with power factor correction as claimed in claim 1, wherein: The controller enables the power factor correction conversion circuit to perform the power factor correction conversion when the adapter output voltage is higher than an enable threshold, and disables the power factor correction conversion circuit to perform the power factor correction conversion when the adapter output voltage is lower than a disable threshold.

4. The power supply system with power factor correction as claimed in claim 1, wherein: The controller adjusts the conversion voltage in a linear manner according to the adapter output voltage.

5. The power supply system with power factor correction as claimed in claim 4, wherein: The controller also adjusts the conversion voltage relative to the adapter output current.

6. The power supply system with power factor correction as claimed in claim 1, wherein: The DC-DC converter includes a flyback converter, an LLC converter, or an active clamp forward converter.

7. The power supply system with power factor correction as claimed in claim 6, wherein: The flyback converter includes an asymmetric half-bridge flyback converter.

8. The power supply system with power factor correction as claimed in claim 1, wherein: The controller adjusts the conversion voltage according to the rectified voltage, the adapter output voltage, and the adapter output current to optimize a conversion efficiency between the rectified voltage and the adapter output voltage.

9. The power supply system with power factor correction as claimed in claim 1, wherein: The controller is used for taking the rectified voltage and the adapter output voltage as inputs of a predetermined algorithm to determine the conversion voltage, so as to achieve a relatively better conversion efficiency.

10. The power supply system with power factor correction as claimed in claim 9, wherein: The predetermined algorithm includes a table lookup method, and the controller selects relatively optimal operating parameters from a pre-stored data table according to the different rectified voltages, the adapter output voltages, and the adapter output currents to adjust the conversion voltage.

11. A power supply system control method, comprising: rectifying an AC input power source to generate a rectified power source, wherein the rectified power source includes a rectified voltage; Performing a power factor correction conversion on the rectified power supply to generate a converted power supply, wherein the converted power supply includes a converted voltage; DC-DC converting the converted power to generate an adapter output power, wherein the adapter output power includes an adapter output voltage and an adapter output current; Determining the adapter output power according to a communication protocol information, and controlling a power path switch to transmit the adapter output power to a power supply pin; and The conversion voltage is determined according to the rectified voltage and the adapter output voltage.

12. The power supply system control method according to claim 11, wherein: When the adapter output voltage decreases, the conversion voltage decreases accordingly.

13. The power supply system control method according to claim 11, wherein: The step of performing a power factor correction conversion on the rectified power supply to generate a converted power supply includes: enabling the power factor correction conversion when the adapter output voltage is higher than an enable threshold, and disabling the power factor correction conversion when the adapter output voltage is lower than a disable threshold.

14. The power supply system control method according to claim 11, wherein: The conversion voltage is adjusted linearly according to the adapter output voltage.

15. The power supply system control method according to claim 14, wherein: The conversion voltage is also related to the adapter output current.

16. The power supply system control method according to claim 11, wherein: The method further includes adjusting the conversion voltage according to the rectified voltage, the adapter output voltage, and the adapter output current to optimize a conversion efficiency between the rectified voltage and the adapter output voltage.

17. The power supply system control method according to claim 11, wherein: The method further includes: using the rectified voltage and the adapter output voltage as inputs of a predetermined algorithm to determine the conversion voltage, so as to achieve a relatively better conversion efficiency.

18. The power supply system control method according to claim 17, wherein: The predetermined algorithm includes a table lookup method for selecting relatively optimal operating parameters from a pre-stored data table according to the different rectified voltages, the adapter output voltages, and the adapter output currents, so as to adjust the conversion voltage.

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