Patent Application
20170310223
The present disclosure relates to a power adapter. More particularly, the present disclosure relates to a power adapter, which selectively provides different output voltages to fit different voltage requirements, and method for fixing DC voltage gain of the power adapter.
Inductor-inductor-capacitor (LLC) power converters are an increasingly important part of power conversion systems. LLC power converters have a number of advantages when compared to other power converters, such as high efficiency. In general, the output voltage of the LLC converter is varied when its input voltage varies; however, this results in high switching loss when the input voltage Vin is small, i.e., under light load.
In order to overcome the problem of high switching loss under light load operation, the LLC converter can be designed to output a determined voltage by fixing its input voltage; however, this gives the LLC converter cannot be compatible for use in different electronic devices.
According to one aspect of the present disclosure, a power adapter applied for powering an electronic device includes a voltage converter, an LLC converter, and a controlling module. The LLC converter is electrically connected to the voltage converter and receives an input voltage provided by the voltage converter. The controlling module with a plurality of controlling modes is electrically connected to the voltage converter, the LLC converter, and the electronic device; the controlling module selects one of the controlling modes in accordance with a voltage requirement of the electronic device, the controlling module further drives the voltage converter to provide the input voltage based on the selected controlling mode, which makes the LLC converter to provide an output voltage to fit the voltage requirement of the electronic device, thus a DC voltage gain of the power adapter is fixed.
In an embodiment of the present disclosure, the controlling module can include a handshaking unit and a controlling unit, the handshaking unit is configured to sense the voltage requirement of the electronic device; and the controlling unit is electrically connected to the handshaking unit, the voltage converter, and the LLC converter. The controlling unit make the LLC converter provide the output voltage to fit the voltage requirement of the electronic device based on a sensed signal generated by the handshaking unit, the controlling unit further regulates the input voltage based on the output voltage fit the voltage requirement of the electronic device to make the DC voltage gain of the power adapter be a constant.
In an embodiment of the present disclosure, the relationship between the outputted voltage and the input voltage is a fixed ratio, and the fixed ratio can be in a range of 16˜20.
In another embodiment of the present disclosure, the fixed DC voltage gain equals to a turns ratio divides by a half of the fixed ratio.
In still another embodiment of the present disclosure, the voltage converter can be a boost converter, a buck converter, a buck-boost converter or a power factor corrector.
According to another aspect of the present disclosure, a method for fixing gain of a power adapter includes following steps: first, a power adapter applied to provide a plurality of output voltages and including an LLC converter is provided; thereafter, a voltage requirement of an electronic device electrically connected to the power adapter is sensed; after that one of the output voltage is selected to fit the voltage requirement of the electronic device, and then an input voltage of the LLC converter is regulated based on the selected output voltage to make the power adapter have a fixed DC voltage gain.
In an embodiment of the present disclosure, the relationship between the outputted voltage and the input voltage is a fixed ratio, and the fixed ratio can be in a range of 16˜20.
The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:
Reference is made to
The power adapter 10 includes a rectifier 100, a voltage converter 110, an LLC (resonant) converter 120, and a controlling module 130. The rectifier 100 is electrically connected to a commercial power source for receiving an alternative current (AC) input voltage AC_IN supplied therefrom. The LLC converter 120 is electrically connected to the electronic device 20, and the voltage converter 110 is arranged between the rectifier 100 and the LLC converter 120 and electrically connected thereto.
The rectifier 100 is configured to rectify the AC input voltage AC_IN into a full-wave rectified direct current (DC) voltage DC_OUT. The rectifier 100 is, for example, a bridge rectifier constituted by four diodes.
The voltage converter 110 is electrically connected to the rectifier 100 and is configured to regulate the full-wave rectified DC voltage DC_OUT and/or correct power factor of the full-wave rectified DC voltage DC_OUT. The voltage converter 110 can be boost converter, buck converter, buck-boost converter, or power factor corrector; the boost converter, the buck converter, and the buck-boost converter are configured to regulate the full-wave rectified DC voltage; the power factor corrector is configured to correct the power factor of the full-wave rectified DC voltage DC_OUT by drawing current in phase of voltage and boost the full-wave rectified DC voltage DC_OUT to an input voltage Vin for delivery to the LLC converter 120.
The LLC converter 120 is electrically connected to the voltage converter 110 and receives the input voltage Vin provided by the voltage converter 110. Reference is made to
The switch assembly S1 includes a power switch Q1 and a diode D1 electrically connected in parallel, and the switch assembly S2 includes a power switch Q2 and a diode D2 electrically connected in parallel. The power switches Q1 and Q2 are, for example, metal-oxide-semiconductor field-effect transistors (MOSFETs). The source of the power switch Q1 is electrically connected to the drain of the power switch Q2, and the drain of the power switch Q1 and the source of the power switch Q2 are electrically connected to the voltage converter 110 shown in
The power switch Q1 and the power switch Q2 receives the input voltage Vin provided by the voltage converter 110; the gates of the power switches Q1 and Q2 receive signals provided by the first feedback controller 140 and then a square wave corresponding to on/off states of the power switches Q1 and Q2 is generated.
The transformer T has a primary winding Wp and a center tapped secondary winding Ws coupled to the primary winding Wp. The resonant capacitor Cr is connected to the source of the power switch Q1 and the drain of the power switch Q2 such that the resonant capacitor Cr receives the square wave corresponding to on/off states of the power switches Q1 and Q2. The magnetizing inductor Lm is electrically connected to the primary winding Wp of the transformer T in parallel. The resonant inductor Lr is arranged between the resonant capacitor Cr and the magnetizing inductor Lm and electrically connected thereto. The resonant capacitor Cr is not only used for blocking DC component of the square wave but also constructing a resonant tank with the resonant inductor Lr and magnetizing inductor Lm.
The rectifying unit 102 includes two rectifying diodes Dr1 and Dr2. The rectifying diodes Dr1 and Dr2 are electrically connected to the secondary windings Ws such that a full-bridge rectifying circuit is constituted to convert an AC voltage outputted from the secondary winding Ws into a DC output voltage with high-frequency ripple component.
The output filter Cf is connected to the rectifying unit 122 and configured to filter high-frequency ripple component of the DC output voltage outputted from the rectifying unit 122 and outputs a stable DC output voltage Vo. The DC output voltage Vo is conducted to the electronic device 20 for powering the electronic device 20.
The LLC converter is based on the fundamental concept that
M=(n×Vo)/(Vin÷2);
where:
M is the DC voltage gain of the LLC converter 120;
n is the turns ratio between the primary winding Wp and the secondary winding Ws of the transformer T;
Vo is the DC output voltage of the LLC converter 120; and
Vin is the input voltage provided from the voltage converter 110 to the LLC converter 120.
Under this fundamental concept, the LLC converter 120 might require very wide frequency range to provide sufficient DC voltage gain when the input voltage Vin varies. This may result in a high switching loss when the input voltage Vin is small, i.e., under light load operation (as curve Q=2 shown in
The voltage converter 110 is typically designed to operate the LLC converter 120 in a fixed input voltage Vin, i.e., the input voltage Vi is a constant. This results in a narrow frequency range of LLC converter 120. Reference is made to
Therefore, the controlling module 130 of the present disclosure is used for the addition function of sensing the DC output voltage Vo of the power adapter 10 and regulating the input voltage Vi of the LLC converter 120 based on the DC output voltage Vo. As a result, a fixed DC voltage gain is provided.
More particularly, the controlling module 130 includes a handshaking unit 132 and a controlling unit 134; the handshaking unit 132 is electrically connected to the LLC converter 120 and the electronic device 20, and the controlling unit 134 is electrically connected to the handshaking unit 132 and the voltage converter 110. The controlling module 130 has a plurality of controlling modes corresponding to different levels of the DC output voltage Vo. The controlling module 130 senses the voltage requirement of the electronic device 20 (i.e., the DC output voltage Vo required for the electronic device 20) and selects one of the controlling modes of the power adapter 10 based on the voltage requirement of the electronic device 20 (may be the instantaneous value of the DC output voltage Vo). Thereafter, the controller module 130 generates signals for driving the voltage converter 110 in accordance with the selected controlling mode, so that the input voltage Vi is regulated. As such, the DC output voltage Vo fit the voltage requirement of the electronic device 20 will delivery to the electronic device 20. The LLC converter 120 is operated within the frequency range between a minimum frequency F-min3 and a maximum frequency F-max3 shown in
Consequently, the power adapter 10 of the present disclosure is capable of providing different DC output voltages Vo with a fixed gain. This gives the power adapter 10 can be compatible for use in different electronic devices 20. In addition, the frequency range between the minimum frequency F-min3 and the maximum frequency F-max3 shown in
With referring again with
As a result, a signal is generated, which is followed by the proper DC output voltage that selected by the electronic device 20. Thereafter, one of the controlling modes should be selected based upon the DC output voltage fit the requirement of the electronic device 20 by the controlling unit 134. The voltage converter 110 is driven, and the input voltage is regulated in accordance with the selected DC output voltage Vo. When the input voltage Vin provided by the voltage converter 110 to the LLC converter 120 is Vin, the DC output voltage of the LLC converter 120 is Vo, and a defined ratio between the DC output voltage Vo and the input voltage Vi is K, the following condition is satisfied:
Vin=K×Vo.
In short, the controlling unit 134 makes the voltage converter 110 provide the input voltage Vi in accordance with the DC output voltage Vo of the selected controlling mode. This gives the DC voltage gain of the power adapter 10 to be a constant. In addition, the power adapter 10 can provide different DC output voltages Vo to fit different voltage requirements of electronic device(s) 20, and the frequency range for operating the LLC converter 120 of the present disclosure is expanded (as shown in
It should be noted that when a minimum of the AC input voltage AC_IN is 80V, the maximum of the DC output voltage Vo of the power adapter 10 is 20V, the minimum of the DC output voltage Vo is 5V, and the defined ration is K, the following condition is satisfied:
16≦K≦20.
Besides, when the DC voltage gain of the power adapter 10 is M, the turns ratio between the primary winding Wp and the secondary winding Ws of the transformer T is n, and the defined ratio is K, the following condition is satisfied:
M=n/(K÷2).
The power adapter 10 further includes the first feedback controller 140 and the second feedback controller 150; the first feedback controller 140 is electrically connected to the LLC converter 120 and configured to control operations of the LLC converter in accordance with the DC output voltage Vo; the second feedback controller 150 is electrically connected to the voltage converter 110 and configured to control operations of the voltage converter 110 in accordance with the input voltage Vin provided by the voltage converter 110 to the LLC converter 120.
With referring again to
Although the present disclosure has been described with reference to the foregoing preferred embodiment, it will be understood that the disclosure is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present disclosure. Thus, all such variations and equivalent modifications are also embraced within the scope of the disclosure as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 105205605 | Apr 2016 | TW | national |
