CN113497568A

CN113497568A - Power adapter

Info

Publication number: CN113497568A
Application number: CN202110292275.7A
Authority: CN
Inventors: 周健; 宋海斌; 许道飞; 章进法
Original assignee: Delta Electronics Shanghai Co Ltd
Current assignee: Delta Electronics Shanghai Co Ltd
Priority date: 2020-04-03
Filing date: 2021-03-18
Publication date: 2021-10-12

Abstract

An embodiment of the present invention provides a power adapter, including: the transformer comprises a primary winding and a secondary winding; the primary side circuit comprises a primary side main switch and is electrically coupled with the primary side winding; a secondary side circuit including a first switching unit and a second switching unit; the first ends of the first switch unit and the second switch unit are coupled with the secondary winding of the transformer, the second ends of the first switch unit and the second switch unit are respectively connected with the first output port and the second output port in a one-to-one correspondence manner, and each output port is used for supplying power to a corresponding load; the control unit samples the output voltage of each output port; and the control unit controls the primary side main switch, the first switch unit and the second switch unit according to the output voltage so as to adjust the output voltage of the corresponding output port. The technical scheme of the invention can realize independent regulation of the output voltage of different output ports of the power adapter and flexible distribution of the output power.

Description

Power adapter

Technical Field

The invention relates to the technical field of power electronics, in particular to a power adapter.

Background

Miniaturization and high power density have become trends in power adapters, and power adapters with multiple output ports have been developed to meet the charging requirements of multiple devices. On the other hand, people have higher and higher requirements on charging speed and charging time, the USB PD type-C power adapter becomes more and more popular, and the output voltage of the novel adapter can be adjusted within a certain range according to the requirements of electric equipment. Among them, the power adapter generally adopts a flyback converter topology, which has a wider application because the circuit is simple, requires few components, and allows a plurality of adjustable outputs to be set from a single circuit. In the related art, two or more output ports are generally connected to the same flyback converter circuit, as shown in fig. 1, the transformer has two secondary windings, the two output ports are respectively connected to the corresponding secondary windings through the secondary circuits, and the flyback converter circuit is connected to the input ac power supply through the bus capacitor and the rectifying circuit. In the structure, because the output voltages of the two output ports are directly related to the turn ratio of the respective secondary winding, the proportional relation of the two output voltages is fixed, and the application requirement that the output voltage of each interface is independently adjustable cannot be met simultaneously.

In another prior art, as shown in fig. 2, one output port of the power adapter is directly connected to the output terminal of the flyback converter 230, and the other output port is connected to the output terminal of the flyback converter 230 through the BUCK circuit 240. Although the method can realize the independent control of the output voltages of the two output ports, the output voltage of the BUCK circuit cannot be higher than the output voltage of the flyback conversion circuit, and the application requirement that the output voltage of each USB interface can be independently adjusted cannot be met at the same time. And because a first-stage BUCK circuit is added, the aspects of volume, efficiency, cost and the like cannot be well considered.

In summary, how to implement independent voltage regulation and flexible power distribution of different output ports of the power adapter is a technical problem that needs to be solved at present.

It is to be noted that the information disclosed in the above background section is only for enhancement of understanding of the background of the present disclosure, and thus may include information that does not constitute prior art known to those of ordinary skill in the art.

Disclosure of Invention

The present disclosure is directed to a power adapter, and therefore, to at least some extent, to achieve independent adjustment of output voltages and flexible allocation of output power to different output ports of the power adapter.

According to an embodiment of the present invention, there is provided a power adapter including: the transformer comprises a primary winding and a secondary winding; the primary side circuit comprises a primary side main switch and is electrically coupled with the primary side winding; a secondary side circuit including a first switching unit and a second switching unit; first ends of the first switch unit and the second switch unit are coupled with a secondary winding of the transformer, second ends of the first switch unit and the second switch unit are respectively connected with a first output port and a second output port in a one-to-one correspondence manner, and each output port is used for supplying power to a corresponding load; a control unit sampling output voltages of the respective output ports; and controlling the primary side main switch, the first switch unit and the second switch unit according to the output voltage so as to adjust the output voltage of the corresponding output port.

In some embodiments, the control unit generates a feedback signal to control the on/off of the primary main switch according to the output voltage of one of the output ports, and controls the on/off of the switch unit corresponding to the other output port according to the output voltage of the other output port.

In some embodiments, the secondary side circuit further comprises a secondary side main switch having a first terminal and a second terminal, the first terminal of the secondary side main switch being connected to one terminal of the secondary side winding, and the second terminal of the secondary side main switch being connected to the first terminal of each switch unit.

In some embodiments, the switch further comprises an intermediate capacitor, a first end of the intermediate capacitor is coupled to the second end of the secondary side main switch, the first end of the first switch unit, and the first end of the second switch unit, and a second end of the intermediate capacitor is connected to the other end of the secondary side winding.

In some embodiments, the secondary side main switch is turned on after the primary side main switch is turned off.

In some embodiments, the control unit controls the first switch unit and the second switch unit to be alternately turned on during the period that the primary side main switch is turned off so as to adjust the output voltage of the corresponding output port.

In some embodiments, the control unit controls a dead time between the first switching unit and the second switching unit.

In some embodiments, during the period when the primary side main switch is turned off, the control unit controls the switch unit with the low voltage at the output port to be turned on first and then controls the switch unit with the high voltage at the output port to be turned on later.

In some embodiments, the control unit includes a first control unit and a second control unit, where the first control unit samples an output voltage of one of the output ports, generates a feedback signal according to the output voltage of the one output port, and controls on/off of the primary main switch, and the second control unit samples an output voltage of the other output port, and controls on/off of a switch unit corresponding to the other output port according to the output voltage of the other output port.

In some embodiments, the switch unit controlled by the second control unit is turned on first, and the other switch unit is turned on later.

In some embodiments, the later-on switching unit is turned on after the earlier-on switching unit is turned off, and is turned off when the secondary winding current is zero.

In some embodiments, the first switch unit and the second switch unit are both bidirectional switch units, and the bidirectional switch units are used for switching on and off bidirectional voltage and bidirectional current.

In some embodiments, the first switching unit and the second switching unit each include a plurality of switching devices connected in series or in parallel.

In some embodiments, the switching device is a MOSFET, GaN, or SiC power device.

In some embodiments, the switching devices in the same switching unit are turned on synchronously or asynchronously with respect to each other.

In some embodiments, the turn-off of the switching devices in the same switching unit are synchronized or not synchronized with each other.

In some embodiments, the first switching unit includes a first switching tube and a second switching tube which are connected in series in an opposite direction, and the second switching unit includes a third switching tube and a fourth switching tube which are connected in series in an opposite direction.

In some embodiments, the drain of the first switch tube is coupled to the secondary winding, the source of the first switch tube is connected to the source of the second switch tube, and the drain of the second switch tube is coupled to the first output port; the drain of the third switching tube is coupled with the secondary winding, the source of the third switching tube is connected with the source of the fourth switching tube, and the drain of the fourth switching tube is coupled with the second output port.

In some embodiments, in a switching period, if the control unit controls the second switching unit to operate first, the first switching unit operates later; the control unit controls the fourth switching tube to be turned off after the third switching tube is turned off, the control unit controls the second switching tube to be turned on before the first switching tube is turned on, and the control unit controls the first switching tube to be turned on after the fourth switching tube is turned off.

In some embodiments, the control unit controls the second switching tube to be turned on after the first switching tube is turned off, and the control unit controls the fourth switching tube to be turned on before the third switching tube is turned on.

In some embodiments, the first output port conforms to USB PD Type-C requirements; the second output port meets the USB PD Type-C requirement.

In some embodiments, the active clamping circuit is connected in parallel with two ends of the primary winding or two ends of the primary main switch, and comprises a clamping switch and a clamping capacitor which are connected in series.

In the power adapter of the embodiment of the invention, the plurality of switch units are arranged in the secondary side circuit, each switch unit is correspondingly connected with one output port, the output voltage and the output power of each output port can be controlled by controlling the flyback conversion circuit and the switch units, and the independent control of the output voltage of the power adapter and the flexible distribution of the output power are realized.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.

Fig. 1 is a schematic diagram illustrating a circuit configuration of a power adapter in the related art;

FIG. 2 is a schematic diagram illustrating another power adapter of the related art;

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

FIG. 3b is a schematic diagram of a power adapter according to another embodiment of the present invention;

FIG. 3c is a schematic diagram of a circuit configuration of a power adapter according to another embodiment of the invention;

FIG. 4 is a timing diagram schematically illustrating driving signals of a switch unit in the power adapter according to an embodiment of the invention;

FIG. 5 is a schematic diagram of a power adapter according to another embodiment of the present invention;

fig. 6 schematically shows a timing chart of driving signals of a bidirectional switch unit in a power adapter according to still another embodiment of the present invention;

FIG. 7 is a schematic diagram of a circuit configuration of a power adapter according to another embodiment of the invention;

fig. 8 schematically shows a timing chart of driving signals of a switching unit in a power adapter according to still another embodiment of the present invention;

fig. 9 is a schematic circuit diagram of a power adapter according to still another embodiment of the present invention;

fig. 10 schematically shows a timing chart of driving signals of a bidirectional switch unit in a power adapter according to still another embodiment of the present invention;

FIG. 11 is a schematic diagram illustrating the variation of current in a power adapter in accordance with an embodiment of the present invention;

FIG. 12 is a schematic diagram illustrating the variation of current in a power adapter according to another embodiment of the present invention;

fig. 13 is a schematic diagram showing a current change of a power adapter according to still another embodiment of the present invention.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or micro-control unit means.

The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.

An embodiment of the present invention provides a power adapter, wherein fig. 3a provides a schematic circuit structure diagram of the power adapter of an embodiment, and as shown in fig. 3a, the power adapter has two output ports, for example, a first output port OUT1 and a second output port OUT 2. The number of output ports is not limited to this, and in other embodiments, there may be three or more output ports. Further, the power adapter in the embodiment of the present invention further includes a rectifying circuit 310, a bus capacitor 320, and a flyback converter circuit 330, where an input end of the rectifying circuit 310 is connected to the AC power supply, and an output end is connected to the bus capacitor 320; the input terminal of the flyback converter 330 is connected to the bus capacitor 320, and the output terminals of the flyback converter 330 are respectively coupled to the corresponding output ports. The flyback converter circuit 330 includes: the transformer TR comprises a primary winding and a secondary winding; the primary side circuit comprises a primary side main switch Q1 and is electrically coupled with the primary side winding; a secondary side circuit including two bidirectional switching units, e.g., a first switching unit S1 and a second switching unit S2; first terminals of the first and second switching units S1 and S2 are connected to the secondary winding of the transformer TR, and second terminals of the first and second switching units S1 and S2 are coupled to corresponding first and second output ports OUT1 and OUT2, respectively, each for supplying power to a corresponding load.

In some embodiments, the first switch unit S1 and the second switch unit S2 may be bidirectional switch units, which can switch bidirectional voltage and bidirectional current, i.e., can switch bidirectional voltage and bidirectional current.

In some embodiments, the bidirectional switching unit may include a plurality of switching devices connected in series, in parallel, or in series-parallel. Further, in some embodiments, the switching device may be a power device such as a MOSFET, GaN, or SiC, which is not limited herein. In some embodiments, the switching device may also be formed by an IGBT diode connected in anti-parallel across the IGBT. For the switching device having the reverse conduction function, two switching devices are required to be connected in series in reverse to block reverse conduction, so that the side with high output voltage is prevented from flowing to the side with low output voltage. In other embodiments, the bidirectional switch unit may be further formed by connecting a switching device and a diode in series and then connecting the switching device and the diode in anti-parallel, which is not limited in this case.

Further, in some embodiments, the flyback converter circuit 330 also includes an active clamp circuit. For example, the active clamp circuit is connected in parallel across the primary winding or across the primary main switch Q1. The active clamp circuit includes a clamp switch and a clamp capacitor connected in series. The clamp switch may be a power switch Q2 as shown in fig. 3a, or may be a diode as shown in fig. 3 b.

In practical applications, the power adapter may have a plurality of output ports, and the secondary side circuit of the transformer correspondingly includes a plurality of switch units, and the second end of each switch unit is coupled to one output port in a one-to-one correspondence manner. By controlling the switch unit, the control of the output voltage and the output power of the plurality of output ports can be realized, and the independent regulation of the output voltage of the plurality of output ports and the flexible distribution of the output power can be realized.

Further, the power adapter further includes a control unit 340, where the control unit 340 samples output voltages of the output ports, and controls the primary side main switch, the first switch unit, and the second switch unit according to the output voltages to adjust output voltages of the corresponding output ports.

Further, in some embodiments, the control unit 340 generates a feedback signal according to the output voltage of one of the output ports, so as to control the primary side main switch Q1, and controls the on/off of the corresponding switch unit according to the output voltage of the other output port. In some embodiments, the control unit 340 includes a first control unit and a second control unit, wherein the first control unit samples the output voltage of one of the output ports and generates a feedback signal to control the on/off of the primary main switch Q1 according to the output voltage of the one of the output ports, and the second control unit 342 samples the output voltages of the other output ports and controls the on/off of the corresponding switch unit according to the output voltages of the other output ports.

Specifically, as shown in fig. 3c, the power adapter includes a first control unit 341 and a second control unit 342, wherein the first control unit 341 generates a feedback signal for controlling the primary side main switch Q1 according to the output voltage of one of the output ports (e.g., OUT1), and the second control unit 342 controls the on/off of the corresponding switch unit (e.g., S2) according to the output voltage of the other output port (e.g., OUT 2). Of course, the first control unit 341 may also control the primary side main switch Q1 according to the output voltage of the second output port OUT2, and the second control unit 342 may control the first switch unit S1 according to the output voltage of the first output port OUT1, which is not limited in this case.

It should be noted that, in some embodiments, the switching on and off of the primary side main switch and the switching unit may be implemented by one control unit, or may be implemented by different control units. In some embodiments, the first control unit 341 and the second control unit 342 may be independent control chips or may be integrated together, which is not limited in this application.

Further, during the period that the primary side main switch Q1 is turned off, the control unit may control the plurality of switch units to be turned on in sequence to adjust the output voltage of the corresponding output port. And the control unit can also control the action between two adjacent conducting switch units to have dead time. Taking the two switch units in fig. 3 as an example, fig. 4 shows a timing diagram of driving signals of the switch unit according to an embodiment of the invention. As shown in fig. 4, the control unit controls the first switching unit S1 and the second switching unit S2 to be sequentially turned on during the turn-off of the primary side main switch Q1, and also controls the dead time t between the first switching unit S1 and the second switching unit S2_d1To prevent the first switching unit S1 and the second switching unit S2 from being turned on simultaneously. In this embodiment, the control unit may control the second switch S2 to be turned on first and the first switch S2 to be turned on later, which is not limited thereto. In other embodiments, the control unit may also control the first switch S1 to be turned on first and the second switch S2 to be turned on later.

Further, in some embodiments, the control unit controls the switch unit with low output voltage to be turned on first, and the switch unit with high output voltage to be turned on later. Specifically, for example, the output voltage of the second output port OUT2 is low, the output voltage of the first output port OUT1 is high, and the control unit may control the second output port OUT2 to be turned on first and control the first output port OUT1 to be turned on later. Further, the first control unit 341 may detect the output voltage of the first output port OUT1, control the primary side main switch Q1 to turn on and off according to the output voltage of the first output port OUT1, and after the primary side main switch Q1 is turned off, the second control unit 342 controls the second switch unit S2 to turn on first according to the output voltage of the second output port OUT2, wherein the first switch unit S1 may not need to be controlled according to the output voltage thereof, that is, after the second switch unit S2 is turned off, the first switch unit S1 is turned on, and when the secondary side winding current is zero, the second switch unit S1 is turned off.

Specifically, in some embodiments, as shown in fig. 5, the first switching unit S1 includes a first switching tube Q201 and a second switching tube Q202 connected in series in an opposite direction, and the second switching unit S2 includes a third switching tube Q203 and a fourth switching tube Q204 connected in series in an opposite direction. In this embodiment, the source of the first switching tube Q201 is connected to the secondary winding, the drain of the first switching tube Q201 is connected to the drain of the second switching tube Q202, and the source of the second switching tube Q202 is connected to the first output port OUT 1; the source of the third switching tube Q203 is connected with the secondary winding, the drain of the third switching tube Q203 is connected with the drain of the fourth switching tube Q204, and the source of the fourth switching tube Q204 is connected with the second output port OUT 2. The first switching tube Q201, the second switching tube Q202, the third switching tube Q203 and the fourth switching tube Q204 may be MOSFETs or GaN or SiC power devices, which is not limited in the present application. In other embodiments, the first switching tube Q201, the second switching tube Q202, the third switching tube Q203 and the fourth switching tube Q204 may also be implemented by antiparallel diodes on an IGBT.

In other embodiments, the drain of the first switching tube Q201 may also be connected to the secondary winding, the source of the first switching tube Q201 is connected to the source of the second switching tube Q202, and the drain of the second switching tube Q202 is connected to the first output port OUT 1; the drain of the third switching tube Q203 is connected with the secondary winding, the source of the third switching tube Q203 is connected with the source of the fourth switching tube Q204, and the drain of the fourth switching tube Q204 is connected with the second output port OUT 2.

In some embodiments, when the first switch unit S1 and the second switch unit S2 of the power adapter shown in fig. 5 are controlled, the control unit may control the first switch tube Q201 and the second switch tube Q202 to operate simultaneously, and control the third switch tube Q203 and the fourth switch tube Q204 to operate simultaneously. As shown in fig. 6, the control timings of the first switching tube Q201 and the second switching tube Q202 are the same, and the control timings of the third switching tube Q203 and the fourth switching tube Q204 are the same. Further, in the embodiment of the present invention, the first switch Q201 and the second switch Q202 are turned on t_cPost-turn off, and post-turn off delay t_d1And the third switching tube Q203 and the fourth switching tube Q204 are turned on again to prevent the two bidirectional switching units from being shared.

In other embodiments, the control unit may further control the timing of the driving signals of the first switch Q201 and the second switch Q202 to be asynchronous, and the timing of the driving signals of the third switch Q203 and the fourth switch Q204 to be asynchronous.

Further, in some embodiments, as shown in fig. 7, the secondary side circuit of the flyback converter further includes a secondary side main switch Q2 having a first terminal and a second terminal, the first terminal of the secondary side main switch Q2 is connected to the secondary side winding, and the second terminal is connected to both the first terminal of the first switch unit S1 and the first terminal of the second switch unit S2. Further, the secondary side circuit of the power adapter in the embodiment of the present invention further includes an intermediate capacitor C2, a first terminal of the intermediate capacitor C2 is coupled to the second terminal of the secondary side main switch Q2 and the first terminals of the first switch unit S1 and the second switch unit S2, and a second terminal of the intermediate capacitor C2 is connected to the secondary side winding. The intermediate capacitor C2 can absorb the voltage spike occurring in the secondary winding.

Fig. 8 is a timing diagram of driving signals of a switch unit in the power adapter according to an embodiment of the invention. The secondary side main switch Q2 is switched on after the primary side main switch Q1 is switched off. Also, in some embodiments, the control unit controls the first and second switching units S1 and S2 to be turned on in sequence during the turn-off of the primary side main switch Q1, and the control unit also controls the dead time t between the first and second switching units S1 and S2_d1So as to inhibit the two switch units from being shared.

Fig. 9 is a schematic circuit structure diagram of a power adapter according to an embodiment of the present invention, and as shown in fig. 9, the flyback converter circuit includes a secondary main switch Q2 and an intermediate capacitor C2, a drain of a first switch Q601 is connected to a second end of the secondary main switch Q2, a source of the first switch Q601 is connected to a source of a second switch Q602, and a drain of the second switch Q602 is connected to a first output port OUT 1; the drain of the third switching tube Q603 is connected to the second end of the secondary side main switch, the source of the third switching tube Q603 is connected to the source of the fourth switching tube Q604, and the drain of the fourth switching tube Q604 is connected to the second output port OUT 2. In some embodiments, the first switching tube Q601, the second switching tube Q602, the third switching tube Q603, and the fourth switching tube Q604 may be MOSFETs, GaN transistors, or SiC transistors, which is not limited herein. In other embodiments, this can also be achieved by antiparallel diodes on the IGBT.

Likewise, the control unit may control the first switching tube Q601, the second switching tube Q602, the third switching tube Q603, and the fourth switching tube Q604 to be periodically turned on and off to control the output voltage and the output power of the plurality of output ports. In some embodiments, the control unit may control the first switching tube Q601 and the second switching tube Q602 to act simultaneously, and control the third switching tube Q603 and the fourth switching tube Q604 to act simultaneously. That is, the control timing of the driving signals of the first switching tube Q601 and the second switching tube Q602 is the same, and the control timing of the driving signals of the third switching tube Q603 and the fourth switching tube Q604 is the same. Further, in some embodiments, there is a dead time t in the action between the first switching unit S1 and the second switching unit S2_d1To prevent the two paths from being common.

In other embodiments, the control unit may also control the timing of the driving signals of the first switch Q601 and the second switch Q602 to be asynchronous, and the control timing of the driving signals of the third switch Q603 and the fourth switch Q604 to be asynchronous. Taking the circuit structure shown in fig. 9 as an example, assuming that the driving signal output by the control unit is as shown in fig. 10, and the output voltage of the second output port OUT2 is lower than the output voltage of the first output port OUT1, at this time, the second switch unit S2 may be controlled to operate first, so that the second output port OUT2 supplies power to the load output first. In some embodiments, the control unit may further control the third switching tube Q603 and the fourth switching tube Q604 to be turned on simultaneously, and control the fourth switching tube Q604 to be turned off after the third switching tube Q603 is turned off, and may further control the first switching tube Q601 and the second switching tube Q602 to be turned off simultaneously, and control the second switching tube Q602 to be turned on before the first switching tube Q601 is turned on. Specifically, as shown in fig. 10, the control unit controls the fourth switch Q604 to pass a first preset time t after the third switching tube Q603 is turned off_Δ1Is turned off, and the first switching tube Q601 is also controlled to pass a second preset time t after the second switching tube Q602 is turned on_Δ2Is turned on. Wherein, the second switch tube Q602 and the fourth switch tubeQ604 can implement ZVS soft switching, reducing losses. In this embodiment, the second switch tube Q602 is turned on before the fourth switch tube Q604 is turned off; in other embodiments, the second switching tube Q602 may be turned on after the fourth switching tube Q604 is turned off, which is not limited in this disclosure. However, it is necessary to ensure that the first switch Q601 is turned on after the fourth switch Q604 is turned off to prevent the second output port OUT2 from supplying power to the first output port OUT 1.

Further, in some other embodiments, when the second output port OUT2 needs to supply power, the fourth switching tube Q604 may be turned on first, and then the third switching tube Q603 is turned on, so that the fourth switching tube Q604 realizes ZVS soft switching, and the loss is reduced. When the power supply of the second output port OUT2 is finished, the third switching tube Q603 and the fourth switching tube Q604 may be turned off at the same time, or the third switching tube Q603 may be turned off first and then the fourth switching tube Q604 may be turned off. Similarly, when the first output port OUT1 needs to supply power to the load, the first switching tube Q601 and the second switching tube Q602 may be turned on at the same time, or the second switching tube Q602 may be turned on first and then the first switching tube Q601 may be turned on; when the first output port OUT1 finishes supplying power to the load, the first switching tube Q601 and the second switching tube Q602 may be turned off at the same time, or the first switching tube Q601 may be turned off first and then the second switching tube Q602 may be turned off. The present application is not limited thereto.

It should be noted that, if the positions of the first switching tube Q601 and the second switching tube Q602 are reversed in fig. 9, the positions of the third switching tube Q603 and the fourth switching tube Q604 are reversed, so as to form the structure shown in fig. 5. Furthermore, the driving of the first switching transistor Q201 in fig. 5 corresponds to the driving of the second switching transistor Q602 in fig. 10, the driving of the second switching transistor Q202 in fig. 5 corresponds to the driving of the first switching transistor Q601 in fig. 10, the driving of the third switching transistor Q203 in fig. 5 corresponds to the driving of the fourth switching transistor Q604 in fig. 10, and the driving of the fourth switching transistor Q204 in fig. 5 corresponds to the driving of the third switching transistor Q603 in fig. 10. And is not expanded here.

Further, in some embodiments, the control unit may control the switch unit with the low voltage at the output port to be turned on first, and the switch unit with the high voltage at the output port to be turned on later. Specifically, as shown in fig. 11, assuming that the output voltage Vo1 of the first output port OUT1 is greater than the output voltage Vo2 of the second output port OUT2, i.e., Vo 1> Vo2, the second switch unit S2 is turned on first, and then the first switch unit S1 is turned on. As shown in fig. 11, in the area indicated by the arrow S2 ON, for example, the third switching tube Q603 and the fourth switching tube Q604 are turned ON, and the first switching tube Q601 and the second switching tube Q602 are not turned ON, where the output voltage of the second output port is Vo2, the output power is Po2, and the falling slope of the secondary current is k2 ═ Vo 2/Ls. In the region indicated by the arrow of S1 ON, the first switching tube Q601 and the second switching tube Q602 are turned ON, and the third switching tube Q603 and the fourth switching tube Q604 are turned off, where the output voltage of the first output port is Vo1, the output power is Po1, and the slope of the secondary current drop is k1 ═ Vo 1/Ls. In this mode, Vo1 is greater than Vo2, so k1 is greater than k2, and therefore the second switch unit S2 with low output voltage is turned on first, and the slope of the secondary current is small, so that the second switch unit S2 only needs to be turned on for a short time tc to meet the requirement of output power. The first switching unit S1 is then turned on, and the first switching unit S1 is turned off when the secondary winding current is zero. Therefore, the switching period of the whole power adapter is short, the loss is small, and the efficiency is high. The second switching unit S1 may be controlled according to the output voltage of the second output port by the second control unit, and the first switching unit S1 may not need to be controlled according to the output voltage. The control scheme enables the switching frequency of the power adapter to change along with the change of the load, and the change range is small, so that the design of the controller and the design of EMI filtering are facilitated.

In other embodiments, as shown in fig. 12, the first output port OUT1 may be turned ON first, then the second output port OUT2 is turned ON, and in the region indicated by the arrows of S1 ON, the first switching tube Q601 and the second switching tube Q602 are turned ON, and the third switching tube Q603 and the fourth switching tube Q604 are not turned ON, at this time, the output voltage of the first output port is Vo1, and the output power is Po 1. In the area indicated by the arrow Q603 ON, the third switching tube Q603 and the fourth switching tube Q604 are turned ON, and the first switching tube Q601 and the second switching tube Q602 are turned off, at this time, the output voltage of the second output port is Vo2, and the output power is Po 2.

Further, in some embodiments, as shown in fig. 13, the first switch unit S1 may be turned on first to supply power to the first output port OUT1, then the second switch unit S2 is turned on to supply power to the second output port OUT2, then the first switch unit S1 is turned on to supply power to the first output port OUT1, so as to meet the requirement of output power of each output port.

Power adapter of the embodiments of the present invention, in the power adapter of the embodiments of the present invention, a plurality of switch units are disposed in the secondary side circuit, each switch unit is correspondingly connected to one output port, and the output voltage and the output power of the output port can be controlled by controlling the switch units, thereby realizing independent adjustment of the output voltages of different output ports of the power adapter and flexible allocation of the output power

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims

1. A power adapter, comprising:

the transformer comprises a primary winding and a secondary winding;

the primary side circuit comprises a primary side main switch and is electrically coupled with the primary side winding;

a secondary side circuit including a first switching unit and a second switching unit; first ends of the first switch unit and the second switch unit are coupled with a secondary winding of the transformer, second ends of the first switch unit and the second switch unit are respectively connected with a first output port and a second output port in a one-to-one correspondence manner, and each output port is used for supplying power to a corresponding load;

a control unit sampling output voltages of the respective output ports; and controlling the primary side main switch, the first switch unit and the second switch unit according to the output voltage so as to adjust the output voltage of the corresponding output port.

2. The power adapter as claimed in claim 1, wherein the control unit generates a feedback signal to control the on/off of the primary side main switch according to the output voltage of one of the output ports, and controls the on/off of the switch unit corresponding to the other output port according to the output voltage of the other output port.

3. The power adapter as claimed in claim 1, wherein the secondary side circuit further comprises a secondary side main switch having a first terminal and a second terminal, the first terminal of the secondary side main switch being connected to one terminal of the secondary side winding, the second terminal of the secondary side main switch being connected to the first terminal of each switch unit.

4. The power adapter as claimed in claim 3, further comprising an intermediate capacitor, wherein a first end of the intermediate capacitor is coupled to the second end of the secondary side main switch, the first end of the first switch unit and the first end of the second switch unit, and the second end of the intermediate capacitor is connected to the other end of the secondary side winding.

5. The power adapter as described in claim 3, wherein said secondary side main switch is turned on after said primary side main switch is turned off.

6. The power adapter as claimed in claim 1 or 3, wherein the control unit controls the first switch unit and the second switch unit to be alternately turned on during the period that the primary side main switch is turned off to adjust the output voltage of the corresponding output port.

7. The power adapter as claimed in claim 6, wherein the control unit controls a dead time between the first switching unit and the second switching unit.

8. The power adapter as claimed in claim 6, wherein during the period of the primary side main switch being turned off, the control unit controls the switch unit with the low voltage at the output port to be turned on first and then to be turned on after the switch unit with the high voltage at the output port.

9. The power adapter according to any one of claims 1-3, wherein the control unit comprises a first control unit and a second control unit, wherein the first control unit samples the output voltage of one of the output ports and generates a feedback signal to control the on/off of the primary side main switch according to the output voltage of the one output port, and the second control unit samples the output voltage of the other output port and controls the on/off of the switch unit corresponding to the other output port according to the output voltage of the other output port.

10. The power adapter as claimed in claim 9, wherein the switch unit controlled by the second control unit is turned on first, and the other switch unit is turned on later.

11. The power adapter as claimed in claim 10, wherein the switch unit that is turned on later is turned on after the switch unit that was turned on earlier is turned off, and is turned off when the secondary winding current is zero.

12. The power adapter as claimed in claim 1 or 3, wherein the first switch unit and the second switch unit are both bidirectional switch units, and the bidirectional switch units realize on-off of bidirectional voltage and bidirectional current.

13. The power adapter as claimed in claim 1 or 3, wherein the first switching unit and the second switching unit each comprise a plurality of switching devices, the plurality of switching devices being connected in series or in parallel.

14. The power adapter as described in claim 13, wherein the switching device is a MOSFET, GaN or SiC power device.

15. The power adapter as claimed in claim 13, wherein the switching devices in the same switching unit are turned on synchronously or asynchronously with respect to each other.

16. The power adapter as claimed in claim 13, wherein the switching devices in the same switching unit are synchronized in turn-off or out of synchronization with each other.

17. The power adapter as claimed in claim 13, wherein the first switch unit comprises a first switch tube and a second switch tube connected in series in opposite directions, and the second switch unit comprises a third switch tube and a fourth switch tube connected in series in opposite directions.

18. The power adapter as recited in claim 17,

the drain electrode of the first switching tube is coupled with the secondary winding, the source electrode of the first switching tube is connected with the source electrode of the second switching tube, and the drain electrode of the second switching tube is coupled with the first output port;

the drain of the third switching tube is coupled with the secondary winding, the source of the third switching tube is connected with the source of the fourth switching tube, and the drain of the fourth switching tube is coupled with the second output port.

19. The power adapter as claimed in claim 18, wherein in a switching cycle, if the control unit controls the second switching unit to operate first, the first switching unit operates later; the control unit controls the fourth switching tube to be turned off after the third switching tube is turned off, the control unit controls the second switching tube to be turned on before the first switching tube is turned on, and the control unit controls the first switching tube to be turned on after the fourth switching tube is turned off.

20. The power adapter as claimed in claim 19, wherein the control unit controls the second switching tube to be turned on after the first switching tube is turned off, and the control unit controls the fourth switching tube to be turned on before the third switching tube is turned on.

21. The power adapter as claimed in claim 1, further comprising an active clamp circuit connected in parallel across the primary winding or across the primary main switch, the active clamp circuit comprising a clamp switch and a clamp capacitor connected in series.

22. The power adapter as claimed in claim 1, wherein the first output port conforms to USB PD Type-C requirements; the second output port meets the USB PD Type-C requirement.