CN217935460U - Power supply circuit of flyback converter - Google Patents
Power supply circuit of flyback converter Download PDFInfo
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- CN217935460U CN217935460U CN202222367115.7U CN202222367115U CN217935460U CN 217935460 U CN217935460 U CN 217935460U CN 202222367115 U CN202222367115 U CN 202222367115U CN 217935460 U CN217935460 U CN 217935460U
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Abstract
The utility model relates to a power supply circuit of a flyback converter, which comprises an auxiliary power supply generating circuit, a switch power supply circuit and a switch control unit; the auxiliary power supply generation circuit comprises a first diode and a first capacitor; an anode of the first diode receives output voltage information of the flyback converter; the cathode of the first diode is connected with the first end of the first capacitor; the second end of the first capacitor is grounded; the common end of the first diode and the first capacitor outputs an auxiliary voltage; the input end of the switching power supply circuit is used for receiving the auxiliary voltage; the output end of the switching power supply circuit is used for providing working voltage for the switching control unit; the switch control unit is used for controlling the grid electrode of the first power tube. The utility model discloses can provide stable voltage for the on-off control unit, can reduce external component quantity simultaneously, improve its conversion efficiency about half simultaneously.
Description
Technical Field
The utility model relates to a switching power supply field, concretely relates to flyback converter's power supply circuit and power supply method.
Background
Fig. 1 is a schematic circuit diagram of the prior art. Flyback topologies have been widely used in power adapters. As shown in fig. 1, in the flyback topology, the output winding W2 of the transformer 1 has a turn ratio relationship with the auxiliary winding W3, and the auxiliary winding W3 generates an auxiliary power V1 by using the first diode D1 and the first capacitor C1, and the auxiliary power V1 is used for providing a stable dc power to the controller 2.
When the output voltage VO of the power adapter changes, the auxiliary power supply V1 also changes along with the change of the output voltage VO, and a proportional relationship exists between the auxiliary power supply V1 and the output voltage VO, wherein the proportional relationship is adjusted by a turn ratio relationship between the output winding W2 and the auxiliary winding W3. Due to the application of the Power Delivery (PD) charging protocol, the output voltage range of the Power adapter is wide (3.3V to 20V), but in order to ensure the normal operation of the switch control unit 202 in the controller 2, the Power pin VDD has a certain operation threshold range, which cannot be too high or too low. Even if the proportional relationship between the auxiliary power supply V1 and the output voltage VO is adjusted by the transformer, the power supply pin VDD may still be out of the operating range. In the prior art, the auxiliary power supply V1 needs to be regulated by a linear regulator (LDO) and then provided to the power supply pin VDD of the controller 2 as the power supply voltage of the controller 2, that is, the power supply voltage of the switch control unit 202 in the controller 2.
When the voltage difference between the auxiliary power supply V1 and the power pin VDD is too large, the linear voltage regulator circuit will have a large loss due to the presence of the transistor BJT, the Zener diode Zener, the current limiting resistor r, and other elements in the LDO, and particularly, when the power adapter operates at a high output voltage (e.g., 20V) and a low load, the overall loss will be especially apparent in the linear voltage regulator circuit.
SUMMERY OF THE UTILITY MODEL
To the not enough of prior art, the utility model discloses a flyback converter's supply circuit.
The utility model discloses the technical scheme who adopts as follows:
a power supply circuit of a flyback converter comprises a transformer and a first power tube; the transformer includes an input winding; the first end of the input winding is connected with an input voltage; the second end of the input winding is connected with the first pole of the first power tube; the second pole of the first power tube is grounded;
the power supply circuit comprises an auxiliary power supply generating circuit, a switching power supply circuit and a switching control unit; the auxiliary power supply generation circuit comprises a first diode and a first capacitor; an anode of the first diode receives output voltage information of the flyback converter; the cathode of the first diode is connected with the first end of the first capacitor; the second end of the first capacitor is grounded; the common end of the first diode and the first capacitor outputs an auxiliary voltage; the input end of the switching power supply circuit is used for receiving the auxiliary voltage; the output end of the switching power supply circuit is used for providing working voltage for the switching control unit; the switch control unit is used for controlling the grid electrode of the first power tube.
The further technical scheme is that the switching power supply circuit is a boost circuit.
The further technical scheme is that the power supply circuit comprises an inductor and a controller; the controller comprises a power supply control unit and the switch control unit; the power supply control unit comprises a second power tube and a second diode; a first pole of the second power tube is used as a first pin of the controller; the second pole of the second power tube is grounded; the first pole of the second power tube is connected with the anode of the second diode; the cathode of the second diode outputs the working voltage to the switch control unit; the first end of the inductor is connected with the common end of the first diode and the first capacitor; and the second end of the inductor is connected with a first pin of the controller.
The output end of the switch control unit is used as a fourth pin of the controller; and the grid electrode of the first power tube is connected with a fourth pin of the controller.
The power supply circuit further comprises an output voltage detection circuit; the output voltage detection circuit receives output voltage information of the flyback converter and outputs a first voltage related to the output voltage; the switching power supply circuit comprises a second power tube; the first voltage is used for controlling a grid electrode of the second power tube.
The further technical scheme is that the output voltage detection circuit comprises an auxiliary winding coupled with the input winding; the output voltage detection circuit receives the output voltage information of the flyback converter through the auxiliary winding and outputs a first voltage related to the output voltage.
The further technical scheme is that the output voltage detection circuit also comprises a voltage division circuit; the first end of the auxiliary winding is grounded; the first end of the voltage division circuit is connected with the second end of the auxiliary winding, and the second end of the voltage division circuit is grounded; the output end of the voltage division circuit outputs a first voltage.
The further technical scheme is that the voltage division circuit comprises a first resistor and a second resistor; the first end of the first resistor is connected with the second end of the auxiliary winding; the second end of the first resistor is connected with the first end of the second resistor; the second end of the second resistor is grounded; and the common end of the first resistor and the second resistor is used as the output end of the voltage division circuit.
The further technical scheme is that the auxiliary power supply generation circuit comprises an auxiliary winding coupled with the input winding; the first end of the auxiliary winding is grounded; the anode of the first diode is connected with the second end of the auxiliary winding.
The flyback converter further comprises a third diode and a third capacitor; the transformer includes an output winding; the first end of the output winding is connected with the first end of the third capacitor; the second end of the third capacitor is connected with the cathode of the third diode, and the anode of the third diode is connected with the second end of the output winding; and the common end of the third diode and the third capacitor outputs the output voltage of the flyback converter.
The beneficial effects of the utility model are as follows:
the utility model discloses utilize outside energy storage subassembly inductance, constitute switching power supply circuit with the inside second power tube of power supply control unit and second diode subassembly for replace traditional linear voltage stabilizing circuit, also include the linear voltage stabilizing circuit that transistor BJT, zener diode Zener, current-limiting resistor r constitute, can provide stable voltage for the switching control unit, can reduce external components quantity simultaneously, improve its conversion efficiency about half simultaneously.
In the PD (Power Delivery) application, along with required output Power is different, output voltage can change, but the operating voltage VDD of the switch control unit in the controller has certain threshold range, so, when output voltage is too big or too small, operating voltage VDD also can be too big or too small thereupon, if exceed operating voltage VDD's threshold range, can lead to the switch control unit can't work, the utility model discloses owing to increased the boost circuit, cooperate the auxiliary winding, adjust auxiliary Power supply and output voltage's proportion earlier and maintain within a certain range, later with the too low voltage part of auxiliary Power supply rise through the boost circuit again, make in the scope of wider output voltage, the operating voltage VDD of switch control unit can all keep in the scope of normal work, guarantee that whole controller can normally work.
The utility model can provide the working voltage of the switch control unit with low cost and high efficiency, and the required components in cost are less than the linear voltage stabilizing circuit in the prior art; in terms of efficiency, the switching power supply is used, and the switching power supply is always an extremely efficient power converter architecture, so that the working efficiency of the whole circuit is improved on the whole.
Drawings
Fig. 1 is a schematic diagram of a power supply circuit of a flyback converter in the prior art.
Fig. 2 is a schematic diagram of a power supply circuit of the flyback converter according to an embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention with reference to the drawings.
Fig. 2 is a schematic diagram of a power supply circuit of the flyback converter in the embodiment of the present invention. As shown in fig. 2, the flyback converter includes a transformer 1 and a first power tube T1. The transformer 1 includes an input winding W1 and an output winding W2. A first end of the input winding W1 is connected to the input voltage VIN. The second end of the input winding W1 is connected to the first pole of the first power transistor T1. The second pole of the first power transistor T1 is grounded. The first end of the output winding W2 is connected to the first end of the third capacitor C3, the second end of the output winding W2 is connected to the cathode of the third diode D3, and the anode of the third diode D3 is connected to the second end of the third capacitor C3. A common terminal of the third diode D3 and the third capacitor C3 serves as an output terminal of the flyback converter, and is used for outputting the output voltage VO of the flyback converter. When the first power transistor T1 is turned on, the third diode D3 is in an off state, and energy is stored in the input winding W1. When the first power tube T1 is turned off, the energy stored in the input winding W1 of the transformer 1 is rectified by the output winding W2 and the third diode D3, and filtered by the third capacitor C3, and then is output to the load.
The power supply circuit of the flyback converter comprises an auxiliary power supply generation circuit, a switching power supply circuit and a switching control unit.
The auxiliary power generating circuit includes a first diode D1 and a first capacitor C1. An anode of the first diode D1 receives information of the output voltage VO of the flyback converter, a cathode of the first diode D1 is connected to a first end of the first capacitor C1, and a second end of the first capacitor C1 is grounded. The common terminal of the first diode D1 and the first capacitor C1 outputs the auxiliary voltage V1. Specifically, the auxiliary power generating circuit includes an auxiliary winding W3 coupled to the input winding W1. The first end of the auxiliary winding W3 is grounded; the anode of the first diode D1 is connected to the second end of the auxiliary winding W3, and the anode of the first diode D1 receives the output voltage information of the flyback converter through the auxiliary winding W3. Since the auxiliary winding W3 and the output winding W2 have a turn-ratio relationship, the auxiliary voltage V1 and the output voltage VO have a proportional relationship.
The input terminal of the switching power supply circuit is used for receiving the auxiliary voltage V1. The output terminal of the switching power supply circuit is used to provide the operating voltage VDD to the switch control unit 202. The switch control unit 202 is used for controlling the gate of the first power transistor T1. Specifically, the switching power supply circuit preferably uses a boost circuit. The operating voltage VDD of the switch control unit 202 is controlled within a threshold range by the switching power supply circuit.
Further, the power supply circuit further comprises an output voltage detection circuit. The output voltage detection circuit receives information of an output voltage VO of the flyback converter and outputs a first voltage VS related to the output voltage VO, and the first voltage VS is used for providing a control voltage for the work of the switching power supply circuit. Here, the first voltage VS is defined to vary with the output voltage VO of the flyback converter. For example, it may be positively or negatively correlated. Specifically, the output voltage detection circuit includes an auxiliary winding W3 coupled to the input winding W1. The output voltage detection circuit further includes a voltage divider circuit. The voltage divider circuit includes a first resistor R1 and a second resistor R2. The output voltage detection circuit receives the output voltage VO information of the flyback converter through the auxiliary winding W3. The first end of the auxiliary winding W3 is grounded. The second end of the auxiliary winding W3 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 is grounded. The common terminal of the first resistor R1 and the second resistor R2 outputs a first voltage VS.
As shown in fig. 2, in the present embodiment, the power supply circuit includes an inductor L1 and a controller 2. The controller 2 includes a power supply control unit 201 and a switch control unit 202. A high voltage power supply unit 203 may also be included. The power supply control unit 201 includes a second power transistor T2 and a second diode D2. The inductor L1, the second power tube T2 and the second diode D2 together constitute a switching power supply circuit. Wherein the inductor L1 is a separate element, and the second power tube T2 and the second diode D2 are integrated in the power supply control unit 201.
A first pole of the second power transistor T2 serves as a first pin SW of the controller 2, and a second pole of the second power transistor T2 is grounded. A first pole of the second power transistor T2 is connected to an anode of the second diode D2 inside the power supply control unit 201, a cathode of the second diode D2 outputs the working voltage VDD, and an internal terminal of the controller 2 is connected to a working voltage terminal of the switch control unit 202 to output the working voltage VDD for the switch control unit 202 to work. Meanwhile, the cathode of the second diode D2 also serves as a second pin of the controller 2. The controller 2 further includes a third pin, and an electrical signal input to the controller 2 through the third pin is transmitted to the gate of the second power transistor T2. The output terminal of the switch control unit 202 serves as a fourth pin of the controller 2. The operating voltage VDD input to the operating voltage terminal of the switch control unit 202 has a certain threshold range, and the switch control unit 202 does not work when the operating voltage VDD is too high or too low. A first end of the inductor L1 is connected to a common terminal of the first diode D1 and the first capacitor C1, and a second end of the inductor L1 is connected to the first pin SW of the controller 2. A first end of the second capacitor C2 is connected to the second pin of the controller 2, and a second end of the second capacitor C2 is grounded. The common terminal of the first resistor R1 and the second resistor R2 is connected to the third pin of the controller 2. The fourth pin of the controller 2 is connected to the gate of the first power transistor T1, and controls the operating state of the first power transistor T1.
In this embodiment, the inductor L1, the second power transistor T2 in the controller 2, and the second diode D2 form a boost circuit. The output winding W2 has a turn ratio relationship with the auxiliary winding W3, and the auxiliary winding W3 generates an auxiliary voltage V1 as an auxiliary power supply by using a first diode D1 and a first capacitor C1, and the auxiliary voltage V1 also has a proportional relationship with the output voltage VO. When the output voltage VO varies, the auxiliary voltage V1 also varies with the output voltage VO. The output range of the auxiliary voltage V1 is controlled by controlling the turn ratio of the output winding W2 and the auxiliary winding W3, the voltage is stabilized by the boost circuit, and meanwhile, the excessively low voltage value is increased, so that the working voltage VDD finally provided for the switch control unit 202 is within the threshold range of normal operation, and even if the variation range of the output voltage VO is wide, the working state of the switch control unit 202 is not influenced.
Meanwhile, when the output voltage VO changes, the first resistor R1 and the second resistor R2 detect the change information of the output voltage VO through the auxiliary winding W3 to obtain a first voltage VS related to the output voltage VO, and transmit the first voltage VS to the third pin of the controller 2, and further transmit the first voltage VS to the gate of the second power transistor T2 in the power supply control unit 201, so as to ensure that the boost circuit works normally. Since the first voltage VS is a High-Low signal, the information of the corresponding output voltage VO can be obtained by sampling High voltage (Sample and Hold).
Usually, the variation range of the output voltage VO is between 3.3V and 20V, and the threshold of the operating voltage VDD for normal operation of the switch control unit 202 in the controller 2 is between 6.5V and 40V. The ratio of the output voltage VO and the auxiliary voltage V1 can be controlled in a ratio 1, 1.9 or 1.5 by adjusting the turn ratio relationship between the output winding W2 and the auxiliary winding W3, if the ratio of the output voltage VO and the auxiliary voltage V1 is 1.9. It is understood that similar adjustment methods can be used to adjust the output voltage VO and the operating voltage VDD if they take other values. The working voltage VDD of the switch control unit 202 is guaranteed to be stable and within a normal working voltage threshold range, so that the fourth pin of the controller 2 generates a stable and low-power-consumption voltage to control the first power tube T1, and the first power tube T1 has a stable control voltage and is low in power consumption.
In this embodiment, the inductor L1 belongs to a passive component, and occupies a larger volume under a certain inductance, so that it is designed outside the power supply control unit 201, and the second diode D2 and the second power transistor T2 are active components, and can be designed according to a required power level and easily integrated into an integrated circuit, thereby saving a space for designing a boost circuit for a user and reducing the volume of the whole circuit.
In this embodiment, in the transformer, the first end of the winding is referred to as a homonymous end, and the second end is referred to as a homonymous end. In this embodiment, the first electrode of the power transistor is a drain electrode, and the second electrode of the power transistor is a source electrode, and similarly, the first electrode can also be a source electrode and the second electrode can also be a drain electrode, which has a relationship with the specific type of the power transistor, and does not affect the function of the power transistor as a switch transistor, and when the gate voltage changes, the power transistor is turned on and off.
The switch control unit 202 and the high voltage power supply unit 203 in the controller 2 are both related art. Is not the key point of the protection of the utility model.
The above description is for the purpose of explanation and not limitation of the invention, which is defined in the claims, and any modifications may be made without departing from the basic structure of the invention.
Claims (10)
1. A power supply circuit of a flyback converter is characterized in that the flyback converter comprises a transformer and a first power tube; the transformer includes an input winding; the first end of the input winding is connected with an input voltage; the second end of the input winding is connected with the first pole of the first power tube; the second pole of the first power tube is grounded;
the power supply circuit comprises an auxiliary power supply generating circuit, a switching power supply circuit and a switching control unit; the auxiliary power supply generation circuit comprises a first diode and a first capacitor; an anode of the first diode receives output voltage information of the flyback converter; the cathode of the first diode is connected with the first end of the first capacitor; the second end of the first capacitor is grounded; the common end of the first diode and the first capacitor outputs an auxiliary voltage; the input end of the switching power supply circuit is used for receiving the auxiliary voltage; the output end of the switching power supply circuit is used for providing working voltage for the switching control unit; the switch control unit is used for controlling the grid electrode of the first power tube.
2. The power supply circuit of the flyback converter of claim 1 wherein the switching power supply circuit is a boost circuit.
3. The power supply circuit of the flyback converter of claim 1, wherein the power supply circuit comprises an inductor and a controller; the controller comprises a power supply control unit and the switch control unit; the power supply control unit comprises a second power tube and a second diode; a first pole of the second power tube is used as a first pin of the controller; the second pole of the second power tube is grounded; the first pole of the second power tube is connected with the anode of the second diode; the cathode of the second diode outputs the working voltage to the switch control unit; the first end of the inductor is connected with the common end of the first diode and the first capacitor; and the second end of the inductor is connected with a first pin of the controller.
4. The power supply circuit of the flyback converter of claim 3, wherein an output terminal of the switch control unit is used as a fourth pin of the controller; and the grid electrode of the first power tube is connected with a fourth pin of the controller.
5. The power supply circuit of the flyback converter of claim 1, wherein the power supply circuit further comprises an output voltage detection circuit; the output voltage detection circuit receives output voltage information of the flyback converter and outputs a first voltage related to the output voltage; the switching power supply circuit comprises a second power tube; the first voltage is used for controlling a grid electrode of the second power tube.
6. The flyback converter power supply circuit of claim 5 wherein the output voltage detection circuit includes an auxiliary winding coupled to the input winding; the output voltage detection circuit receives the output voltage information of the flyback converter through the auxiliary winding and outputs a first voltage related to the output voltage.
7. The power supply circuit of the flyback converter of claim 6 wherein the output voltage detection circuit further comprises a voltage divider circuit; the first end of the auxiliary winding is grounded; the first end of the voltage division circuit is connected with the second end of the auxiliary winding, and the second end of the voltage division circuit is grounded; the output end of the voltage division circuit outputs a first voltage.
8. The power supply circuit of the flyback converter of claim 7 wherein the voltage divider circuit comprises a first resistor and a second resistor; the first end of the first resistor is connected with the second end of the auxiliary winding; the second end of the first resistor is connected with the first end of the second resistor; the second end of the second resistor is grounded; and the common end of the first resistor and the second resistor is used as the output end of the voltage division circuit.
9. The flyback converter of claim 1 wherein the auxiliary power generation circuit includes an auxiliary winding coupled to the input winding; the first end of the auxiliary winding is grounded; the anode of the first diode is connected with the second end of the auxiliary winding.
10. The power supply circuit of the flyback converter of claim 1, wherein the flyback converter further comprises a third diode and a third capacitor; the transformer includes an output winding; the first end of the output winding is connected with the first end of the third capacitor; a second end of the third capacitor is connected with a cathode of the third diode, and an anode of the third diode is connected with a second end of the output winding; and the common end of the third diode and the third capacitor outputs the output voltage of the flyback converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222367115.7U CN217935460U (en) | 2022-09-02 | 2022-09-02 | Power supply circuit of flyback converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222367115.7U CN217935460U (en) | 2022-09-02 | 2022-09-02 | Power supply circuit of flyback converter |
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| CN217935460U true CN217935460U (en) | 2022-11-29 |
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| CN202222367115.7U Active CN217935460U (en) | 2022-09-02 | 2022-09-02 | Power supply circuit of flyback converter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115967258A (en) * | 2023-02-21 | 2023-04-14 | 恩赛半导体(成都)有限公司 | Power supply circuit, power supply system and electronic device |
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2022
- 2022-09-02 CN CN202222367115.7U patent/CN217935460U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115967258A (en) * | 2023-02-21 | 2023-04-14 | 恩赛半导体(成都)有限公司 | Power supply circuit, power supply system and electronic device |
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