CN213305252U

CN213305252U - Auxiliary power supply for supplying power to control circuit

Info

Publication number: CN213305252U
Application number: CN202021246355.6U
Authority: CN
Inventors: 刘青峰; 刘军; 王伟哲; 李哲
Original assignee: Astec International Ltd
Current assignee: Astec International Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2021-05-28
Anticipated expiration: 2030-06-30

Abstract

An auxiliary power supply for powering a control circuit is disclosed. The auxiliary power supply includes: an alternating current power supply; a transistor; a high voltage start-up loop configured to start up the control circuit via the transistor during a high voltage start-up phase; a drive voltage source connected to the gate of the transistor and for providing a drive voltage to the transistor under control of the control circuit after the high voltage start-up phase; and a buck circuit configured to maintain an output voltage of the auxiliary power supply at a set value after the high voltage startup phase.

Description

Auxiliary power supply for supplying power to control circuit

Technical Field

The present disclosure relates generally to power electronics, and more particularly to an auxiliary power supply for powering a control circuit such as a PFC (power factor correction) chip.

Background

In conventional power supply designs, an auxiliary power supply is required to power a control IC (integrated circuit), and an auxiliary power supply transformer has a large size. Nowadays, as the demand for small-sized power supplies is higher, how to reduce the size of the auxiliary power supply becomes more important.

Fig. 1 shows a prior art dual power supply circuit that enables power up of a PWM chip U201 by taking two different power supply circuits for different voltage ranges. However, the supply circuit shown in fig. 1 has only a start-up voltage part, and therefore an additional circuit is also required to implement voltage stabilization. In addition, the resistors R201, R202, and R203 in the power supply circuit of fig. 1 require a large size package. Therefore, the design of the dual power supply circuit is complicated and a large-sized package is required.

SUMMERY OF THE UTILITY MODEL

A brief summary of the disclosure is provided below in order to provide a basic understanding of some aspects of the disclosure. It should be understood that this summary is not an exhaustive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

An object of the present disclosure is to provide an auxiliary power supply which is small in size and has a simple circuit design.

According to one aspect of the present disclosure, an auxiliary power supply for powering a control circuit is provided. The auxiliary power supply includes: an alternating current power supply; a transistor; a high voltage start-up loop configured to start up the control circuit via the transistor during a high voltage start-up phase; a drive voltage source connected to the gate of the transistor and for providing a drive voltage to the transistor under control of the control circuit after the high voltage start-up phase; and a buck circuit configured to maintain an output voltage of the auxiliary power supply at a set value after the high voltage startup phase.

Preferably, the high voltage start-up loop includes a first diode, a second diode, a resistor, a zener diode, and a capacitor, the first diode and the second diode being coupled in series to the ac power source and coupled in series in reverse to each other, the first diode, the resistor, and the zener diode being coupled in series, and the second diode, the transistor, and the capacitor being coupled in series.

Preferably, the buck loop comprises an inductor and a third diode, the second diode, the transistor, the inductor, the capacitor, the third diode, the drive voltage source and the resistor being coupled in series.

Preferably, the control circuit is configured to, after being activated, control the drive voltage source to supply a high-level drive voltage so that the transistor is turned on if it is detected that the input voltage from the alternating-current power supply does not exceed a predetermined threshold, and control the drive voltage source to supply a low-level drive voltage so that the transistor is turned off if it is detected that the input voltage exceeds the predetermined threshold.

Preferably, the capacitor is charged during the high voltage start-up phase and supplies the auxiliary power supply with the transistor switched off after the high voltage start-up phase.

Preferably, the auxiliary power supply further includes a fourth diode coupled in series between the resistor and the driving voltage source and coupled to the gate of the transistor.

Preferably, the ac power source is an ac mains supply, and the voltage range of the driving voltage source is between 0 and 20V.

Preferably, the predetermined threshold is 160V, and the set value is between 3.3V and 20V.

Preferably, the zener diode has a regulated voltage value of 3.3V to 25V, and the third diode is a schottky diode having a reverse bias voltage of 200V or less.

Additional aspects of the disclosed embodiments are set forth in the description section that follows, wherein the detailed description is presented to fully disclose preferred embodiments of the disclosed embodiments without imposing limitations thereon.

Drawings

The disclosure may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which like or similar reference numerals are used throughout the figures to designate like or similar components. The accompanying drawings, which are incorporated in and form a part of the specification, further illustrate preferred embodiments of the present disclosure and explain the principles and advantages of the present disclosure, are incorporated in and constitute a part of this specification. Wherein:

FIG. 1 is a circuit diagram showing a prior art dual power supply circuit;

fig. 2 is a circuit diagram illustrating an auxiliary power supply for powering a control circuit according to an embodiment of the present invention;

FIG. 3 is a waveform diagram showing the output voltage and drive current during a high voltage start-up phase;

fig. 4 is a waveform diagram showing the input voltage and the output voltage of the auxiliary power supply of the present invention after the high voltage start-up phase.

Detailed Description

Exemplary embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings. In the interest of clarity and conciseness, not all features of an actual implementation are described in the specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another.

Here, it should be further noted that, in order to avoid obscuring the present disclosure with unnecessary details, only components closely related to the scheme according to the present disclosure are shown in the drawings, and other details not so related to the present disclosure are omitted.

Additionally, in describing the components of the present disclosure, terms such as first, second, A, B, (a), (b), etc. may be used herein. These terms are only used to distinguish one element from another element, and the attribute, order, sequence, and the like of the respective elements are not limited by the respective terms. In the case where one component is described as being "connected to" or "coupled to" another component, it should be construed that the one component may be directly "connected to" or "coupled to" the other component or may be "connected to" or "coupled to" the other component via an intermediate component.

Fig. 2 is a circuit diagram illustrating an auxiliary power supply 100 for supplying power to a control circuit according to an embodiment of the present invention.

As shown in fig. 2, the auxiliary power supply 100 includes an alternating current power supply V2, a driving voltage supply V1, diodes D3, D4, and D7, a zener diode D8, a resistor R7, a transistor Q1, an inductor L1, a capacitor C4, and PVCC terminals. Diodes D3 and D4 are coupled in anti-series. The diode D3, the resistor R7, and the zener diode D8 are coupled in series. Diode D4, transistor Q1, inductor L1, capacitor C4, and diode D7 are coupled in series.

It should be noted that the diodes D1, D2, D5 and D6 in fig. 2 are rear stage rectifier bridges, which are irrelevant to the present invention and will not be described herein again.

Preferably, the ac power source V2 is, for example, ac mains, the driving voltage source V1 is, for example, between 0 and 20V, the zener diode D8 has a regulated voltage value of, for example, 3.3V to 25V, and the diode D7 is, for example, a schottky diode reverse-biased to 200V or less.

During the high voltage start-up phase, diodes D3 and D4, resistor R7, zener diode D8 and capacitor C4 together form a high voltage start-up loop for the control circuit, e.g., a PFC chip. During the high voltage startup phase, the transistor Q1 is controlled to conduct by the ac supply V2, the diode D3, the diode D4, and the resistor R7, and operates in a linear power state. The high-voltage ac power source V2 charges the capacitor C4 via the transistor Q1 and starts the PFC chip connected to the PVCC terminal.

Note that during the high voltage start-up phase, the drive voltage source V1 is not active.

The waveform of the current flowing through the transistor Q1 during the high-voltage startup phase is shown in the upper graph in fig. 3, and the waveform of the output voltage at the PVCC terminal is shown in the lower graph in fig. 3.

After the high voltage start-up phase, the DSP (digital signal processor) of the PFC starts working and issues a switching signal of a set frequency, and then generates a driving voltage for controlling the on and off of the transistor Q1 at the driving voltage source V1 by isolating the driving chip or transformer driving, wherein the transistor Q1 is turned on when the driving voltage is high level, and the gate-source voltage of the transistor Q1 is zero and thus the transistor Q1 is turned off when the driving voltage is low level.

Optionally, a diode D9 is connected in series between the gate of the transistor Q1 and the resistor, for preventing the zener diode D8 from being damaged by the excessive voltage when the transistor Q1 is turned on.

Specifically, the DSP generates a high level driving voltage at the driving voltage source V1 such that the transistor Q1 is turned on if it detects that the input voltage at the node 1 is less than a predetermined threshold, which may be 160V, for example. When the transistor Q1 is turned on, the buck loop formed by the inductor L1 and the diode D7 can maintain the output voltage at the PVCC terminal at a set value, for example, 15V, thereby stably supplying power to the PFC chip.

Conversely, the DSP generates a low level driving voltage at the driving voltage source V1 such that the transistor Q1 turns off if it detects that the input voltage at the node 1 is greater than 160V. At this time, the power supply of the PFC chip is provided by the charge stored in the capacitor C4, so that the output voltage at the PVCC terminal is stably maintained at, for example, 15V.

Thus, after the high voltage start-up phase, a stable output voltage is provided at the PVCC terminal through the buck loop and capacitor C4.

Fig. 4 shows simulated waveforms of the input voltage and the output voltage of the auxiliary power supply 100 after a high voltage start-up phase according to the present invention. The upper graph of fig. 4 is the output voltage waveform at the PVCC terminal, and the lower graph of fig. 4 is the input voltage waveform at node 1. As can be seen from the upper graph of fig. 4, the output voltage is stably maintained between 3.3V and 20V.

It should be understood that l1 in fig. 2 represents the equivalent load current of the auxiliary power supply 100.

It is understood that the transistor Q1 may be any suitable switching device known to those skilled in the art of MOSFETs, such as, but not limited to, MOSFETs (metal oxide semiconductor field effect transistors), Insulated Gate Bipolar Transistors (IGBTs), Junction Field Effect Transistors (JFETs), double gate MOSFETs, and the like.

Note that in conventional digital PFC control, a DSP is also used to detect the input voltage. Therefore, no additional control circuit is required to control the auxiliary voltage 100.

It should also be noted that the auxiliary power supply 100 according to the present invention is a complete auxiliary power supply with a high voltage start. The circuit design of the auxiliary power supply 100 is simple since no additional high voltage start-up circuit is required. Moreover, since the auxiliary power supply 100 according to the present invention operates only at an input voltage of less than 160V, the rectifying diode D7 can use a schottky diode having a smaller size and a reverse bias voltage of 200V or less, and since the inductor L1 is also smaller in size, the overall size of the auxiliary power supply 100 can be reduced. In addition, a lower operating voltage also means lower switching losses.

Therefore, the utility model provides a circuit design is simple, the less and low auxiliary power supply of switching loss of size.

The auxiliary power supply 100 according to the present invention is particularly suitable for a server. It will be appreciated that the invention is not limited thereto but may also be applied to any circuit requiring a regulated voltage supply.

While the disclosure has been disclosed by the description of the specific embodiments thereof, it will be appreciated that those skilled in the art will be able to devise various modifications, improvements, or equivalents of the disclosure within the spirit and scope of the appended claims. Such modifications, improvements and equivalents are also intended to be included within the scope of the present disclosure.

Claims

1. An auxiliary power supply for powering a control circuit, comprising:

an alternating current power supply;

a transistor;

a high voltage start-up loop configured to start up the control circuit via the transistor during a high voltage start-up phase;

a drive voltage source connected to the gate of the transistor and for providing a drive voltage to the transistor under control of the control circuit after the high voltage start-up phase; and

a voltage reduction circuit configured to maintain an output voltage of the auxiliary power supply at a set value after the high voltage startup phase.

2. The auxiliary power supply of claim 1, wherein the high voltage start-up loop comprises a first diode, a second diode, a resistor, a zener diode, and a capacitor, the first diode and the second diode being coupled in series to the ac power source and coupled in series opposite to each other, the first diode, the resistor, and the zener diode being coupled in series, and the second diode, the transistor, and the capacitor being coupled in series.

3. The auxiliary power supply of claim 2, wherein the buck loop comprises an inductor and a third diode, and wherein the second diode, the transistor, the inductor, the capacitor, the third diode, the drive voltage source, and the resistor are coupled in series.

4. The auxiliary power supply of claim 3, wherein the control circuit is configured to, after being activated, control the drive voltage source to provide a high level drive voltage such that the transistor is turned on if it is detected that the input voltage from the AC power supply does not exceed a predetermined threshold, and control the drive voltage source to provide a low level drive voltage such that the transistor is turned off if it is detected that the input voltage exceeds the predetermined threshold.

5. The auxiliary power supply of claim 4, wherein the capacitor is charged during the high voltage start-up phase and powers the auxiliary power supply with the transistor turned off after the high voltage start-up phase.

6. The auxiliary power supply of claim 5, wherein said predetermined threshold is 160V.

7. The auxiliary power supply of any one of claims 2 to 6, further comprising a fourth diode coupled in series between the resistor and the drive voltage source and coupled to the gate of the transistor.

8. An auxiliary power supply as claimed in any one of claims 1 to 6, wherein the AC power supply is AC mains.

9. The auxiliary power supply according to any one of claims 1 to 6, wherein the voltage of the driving voltage source ranges between 0 and 20V.

10. An auxiliary power supply as claimed in any one of claims 1 to 6, wherein the set value is between 3.3V and 20V.

11. The auxiliary power supply according to any one of claims 2 to 6, wherein the zener diode has a regulated voltage value of 3.3V to 25V.

12. The auxiliary power supply according to any one of claims 3 to 6, wherein the third diode is a Schottky diode with a reverse bias of 200V or less.