CN211508896U

CN211508896U - AC/DC power supply and rectifying circuit

Info

Publication number: CN211508896U
Application number: CN202020393059.2U
Authority: CN
Inventors: 骆南; 黄秋凯; 邓建; 王兆丰; 张加亮
Original assignee: Hangzhou Silergy Semiconductor Technology Ltd
Current assignee: Hangzhou Silergy Semiconductor Technology Ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2020-09-15
Anticipated expiration: 2030-03-24

Abstract

An AC/DC power supply and a rectifier circuit are disclosed. The filter circuit in the rectifying circuit generates a power supply voltage which follows the direct current pulsating voltage received by the filter circuit in a first time interval, and the numerical value of the power supply voltage is greater than the numerical value of the power supply voltage at the end moment of the first time interval in a second time interval, so that the size of the filter circuit is reduced, the size of the rectifying circuit is further reduced, and the power density of the AC/DC power supply is improved.

Description

AC/DC power supply and rectifying circuit

Technical Field

The utility model relates to a power electronics technical field specifically, relates to an AC/DC power and rectifier circuit.

Background

At present, a two-stage power supply architecture is generally adopted in the application occasions of AC/DC without PFC requirements. Fig. 1 shows a circuit block diagram of an AC/DC power supply in the prior art, wherein a rectifying circuit is arranged at a front stage and comprises a rectifying bridge for rectifying an AC input voltage Vac into a DC ripple voltage Vbus, wherein the DC ripple voltage Vbus is an absolute value of the AC input voltage Vac. The output end of the rectifier bridge is connected in parallel with a capacitor C to generate a supply voltage Vin. The latter stage is a DC/DC converter for converting the supply voltage Vin to the required voltage level. Fig. 2 shows a waveform diagram of an operation of a rectifier circuit in the prior art. As shown in fig. 2, at time t0, the dc pulsating voltage Vbus rises to the voltage of the capacitor C (i.e., the supply voltage Vin), and thereafter, during the period t0-t1, the rectifier bridge is turned on, the supply voltage Vin follows the dc pulsating voltage Vbus, and the ac input voltage Vac charges the capacitor C and simultaneously supplies energy to the subsequent stage. At time t1, the dc pulsating voltage Vbus drops to be equal to the supply voltage Vin, and thereafter during the period t1-t2, the rectifier bridge is turned off and the capacitor C discharges to supply energy to the following stage, so that the supply voltage Vin drops linearly to be equal to the dc pulsating voltage Vbus at time t 2. After which the rectifier bridge is switched back on and the process is repeated. In the above process, the AC input voltage Vac only powers the following stage during the period t0-t 1. In this application, the supply voltage Vin needs to be within a certain range to ensure the normal operation of the post-stage DC/DC converter. On one hand, in order to meet the voltage requirement under the condition of full load of low-voltage input, a capacitor with a larger capacitance value is often needed. On the other hand, in order to satisfy the withstand voltage requirement at the time of high voltage input, a capacitor having a high withstand voltage is often required. The high capacitance value and the high withstand voltage result in larger capacitance volume, finally result in larger volume of the AC/DC power supply, and reduce the power density of the AC/DC power supply.

Disclosure of Invention

In view of this, the utility model discloses a direct current pulsating voltage after the basis rectifies sets up the mode of operation of the filter circuit in rectifier circuit to reduce filter circuit's volume, and then reduce rectifier circuit's volume.

According to the utility model discloses a first aspect provides a rectifier circuit, include:

the filter circuit is used for receiving the direct current pulsating voltage and generating a supply voltage, wherein the waveform of the supply voltage follows the direct current pulsating voltage in a first time interval; in a second time interval, the value of the supply voltage is greater than the value of the supply voltage at the end of the first time interval, thereby reducing the size of the filter circuit.

Further, in the second time interval, the value of the power supply voltage is smaller than or equal to the peak value of the minimum direct current pulsating voltage.

Further, the filter circuit is in a first operating mode during a first portion of the first time interval, and the filter circuit is in a second operating mode during a second portion of the first time interval and the second time interval.

Further, in the first operating mode, the filter circuit has a first capacitance value; in the second operating mode, the filter circuit has a second capacitance value, wherein the second capacitance value is greater than the first capacitance value.

Further, the direct current pulse voltage provides energy for a post-stage circuit of the rectification circuit in the first time interval.

Further, a first portion of the first time interval starts when the dc ripple voltage rises to a second threshold value and ends when the dc ripple voltage falls to the first threshold value, and a second portion of the first time interval starts when the dc ripple voltage rises to the supply voltage and ends when the dc ripple voltage rises to the second threshold value.

Further, the second time interval starts when the dc pulse voltage decreases to the first threshold value and ends when the dc pulse voltage increases to the supply voltage.

Further, the second threshold is greater than the first threshold and less than or equal to a peak value of a minimum dc ripple voltage.

Further, the filter circuit includes:

the first capacitor is connected to the input end of the filter circuit in parallel; and

and the second capacitor is selectively connected in parallel to the input end of the filter circuit, and the capacitance value of the second capacitor is greater than that of the first capacitor.

Further, the first capacitor is connected in common parallel with the second capacitor during a second portion of the first time interval and the second time interval.

Further, the second capacitor is disconnected from the first capacitor during a first portion of the first time interval.

Further, the filter circuit further includes:

a first switch in series with the second capacitor to selectively connect the second capacitor to the input of the filter circuit.

Further, when the direct current pulse voltage drops to a first threshold value, the first switch is controlled to be conducted so as to connect the first capacitor in parallel with the input end of the filter circuit.

Further, when the direct current pulsating voltage rises to a second threshold value, the first switch is controlled to be turned off so as to disconnect the first capacitor from the input end of the filter circuit.

Further, the rectifier circuit further includes:

and the rectifying unit is used for receiving the alternating current input voltage and outputting direct current pulsating voltage.

According to a second aspect of the present invention, there is provided an AC/DC power supply, comprising:

the rectifier circuit of any of the above; and

a DC/DC converter to convert the supply voltage to a desired voltage level for provision to a load.

In summary, a filter circuit in the rectifier circuit generates a supply voltage, which follows the DC pulsating voltage received by the filter circuit in the first time interval, and in the second time interval, the value of the supply voltage is greater than the value of the supply voltage at the end of the first time interval, so as to reduce the size of the filter circuit, further reduce the size of the rectifier circuit, and improve the power density of the AC/DC power supply.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram of a prior art AC/DC power supply;

FIG. 2 is a waveform diagram illustrating operation of a prior art rectifier circuit;

FIG. 3 is a circuit diagram of an AC/DC power supply according to an embodiment of the present invention; and

fig. 4 is a waveform diagram illustrating operation of the rectifier circuit according to the embodiment of the present invention.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Fig. 3 is a circuit block diagram of an AC/DC power supply according to an embodiment of the present invention. As shown in fig. 3, the front stage is a rectifier circuit 1, and the rear stage is a DC/DC converter 2. The rectifier circuit 1 includes a rectifying unit 11 and a filter circuit 12. The rectifying unit 11 is configured to receive an ac input voltage Vac and rectify it into a dc ripple voltage Vbus, where the dc ripple voltage Vbus is an absolute value of the ac input voltage Vac. Specifically, the rectifying unit 11 includes four diodes constituting bridge rectification. It will be appreciated that the four diodes may also be partially or fully replaced by power tubes. The rectifying unit 11 may further include other circuits with rectifying function, such as a bridgeless LLC circuit, which is not limited herein.

The filter circuit 12 is connected to the output end of the rectifying unit 11, and is configured to receive the DC ripple voltage Vbus and generate a supply voltage Vin to be provided to a DC/DC converter of a subsequent stage, where a waveform of the supply voltage Vin follows the DC ripple voltage Vbus in a first time interval; in the second time interval, the value of the supply voltage Vin is greater than the value of the supply voltage Vin at the end of the first time interval, so that the size of the filter circuit 12 is reduced. Meanwhile, in a second time interval, the power supply voltage Vin is less than or equal to the peak value of the minimum direct current ripple voltage Vbus. Specifically, the filter circuit 12 has two modes of operation. During a first portion of the first time interval, the filter circuit 12 is in the first operating mode; during a second portion of the first time interval and during a second time interval, the filter circuit 12 is in a second mode of operation. In the first operating mode, the filter circuit 12 has a first capacitance value; in the second operation mode, the filter circuit 12 has a second capacitance value, wherein the second capacitance value is greater than the first capacitance value. In the present embodiment, the first part of the first time interval starts from when the dc ripple voltage Vbus rises to the second threshold Vth2 and ends when the dc ripple voltage Vbus falls to the first threshold Vth1, and the second part of the first time interval starts from when the dc ripple voltage Vbus rises to the power supply voltage Vin and ends when the dc ripple voltage Vbus rises to the second threshold Vth 2. The second time interval starts when the dc ripple voltage Vbus falls to the first threshold Vth1 and ends when the dc ripple voltage Vbus rises to the supply voltage Vbus. The first threshold Vth1 can be set according to the minimum operating voltage of the subsequent circuit, and the second threshold Vth2 is greater than the first threshold Vth1 and is not greater than the peak value of the minimum dc ripple voltage Vbus.

In the embodiment, the filter circuit 12 includes a first capacitor C1 and a second capacitor C2, and the capacitance of the second capacitor C2 is much larger than that of the first capacitor C1. The first capacitor C1 is connected in parallel to the input terminal of the filter circuit 12, and the second capacitor C2 is selectively connected in parallel to the first capacitor C1. That is, the first capacitor C1 is connected in parallel to the input of the filter circuit 12 alone in the first operation mode; in the second operation mode, the first capacitor C1 and the second capacitor C2 are connected in parallel to the input terminal of the filter circuit 12.

The filter circuit 12 further includes a switch S in series with the second capacitor C2 to selectively connect the second capacitor C2 in parallel to the input of the filter circuit 12. The switch S is controlled to be turned off in the first working mode and to be turned on in the second working mode. It should be understood that the embodiment of the present invention provides only one implementation manner of the filter circuit, and other circuits capable of implementing this function are all in the protection scope of the present invention. For example, the first capacitor may be connected in series with a switch, which is turned on in the first operation phase and turned off or turned on in the second operation phase, without affecting the effect of the circuit.

The operation process of the rectifier circuit is specifically described below with reference to the operation waveform diagram.

Fig. 4 shows an operation waveform diagram of the rectifier circuit according to the embodiment of the present invention. As shown in fig. 4, the dc pulsating voltage Vbus rises to the second threshold Vth2 at time t0, after which the filter circuit starts to enter the first operation mode. The switch S is controlled to be turned off, i.e. the input of the filter circuit 12 is connected in parallel with the first capacitor C1 only. During the period t0-t1 (i.e. the first part of the first time interval), the supply voltage Vin follows the dc pulsating voltage Vbus due to the small capacitance of the first capacitor C1, and the latter stage is supplied with energy by the first capacitor C1 and the ac input voltage Vac. The dc ripple voltage Vbus starts to decrease after rising to the peak value, and decreases to the first threshold Vth1 at time t1, until the first part of the first time interval ends. Thereafter, the filter circuit 12 enters the second operation mode, and the switch S is controlled to be turned on to connect the second capacitor C2 in parallel with the input terminal of the filter circuit 12. Since the capacitance of the second capacitor C2 is much larger than that of the first capacitor C1, the supply voltage Vin is increased to a voltage approximately equal to the voltage across the second capacitor C2, i.e., the second threshold Vth 2. During the period t1-t2 (i.e. the second time interval), since the supply voltage Vin is greater than the dc pulsating voltage Vbus, the rectifying unit 11 is turned off, so that the first capacitor C1 and the second capacitor C2 jointly supply energy to the subsequent stage, and the supply voltage Vin also linearly decreases as the capacitors discharge. During this period, the dc ripple voltage Vbus decreases to zero and then increases to equal the supply voltage Vin by time t2, and the second time interval ends. After which the rectifying unit 11 is turned on. During the period t2-t3 (i.e. the second part of the first time interval), the filter circuit 12 is still in the second operation mode, and the ac input voltage Vac charges the first capacitor C1 and the second capacitor C2 on the one hand, and supplies energy to the following stages on the other hand. The dc pulsating voltage Vbus continues to rise until time t3, which is greater than the second threshold Vth2, until the second part of the first time interval is over. After that, the filter circuit enters the first operation mode, the switch S is controlled to be turned off, and the voltage value across the second capacitor C2 is Vth2, that is, the maximum voltage value borne by the second capacitor C2 is the second threshold Vth 2.

Therefore, in the present embodiment, the ac input voltage Vac supplies energy to the subsequent stage in both the first portion t0-t1 and the second portion t2-t3 of the first time interval, that is, the time for the ac input voltage Vac to supply energy to the subsequent stage in each period is greatly prolonged compared with fig. 2, so that the capacitors (capacitors C1 and C2) in the filter circuit do not need to have a large capacity, and the subsequent stage circuit can normally operate, thereby being beneficial to reducing the size of the filter circuit. Meanwhile, in fig. 2, since the capacitor C is always connected in parallel to the output end of the rectifying circuit, the voltage withstanding value of the capacitor is equal to the peak value of the maximum dc ripple voltage, whereas in the present embodiment, the voltage withstanding value of the second capacitor C2 is the second threshold Vth2, that is, equal to the peak value of the minimum dc ripple voltage. It should be understood that the peak value of the maximum DC pulsating voltage and the peak value of the minimum DC pulsating voltage herein refer to AC input voltages of different voltage levels received by the rectifier circuit, and thus the DC pulsating voltages have different voltage ranges, for example, in order to meet different load requirements, an AC/DC power supply can receive AC input voltages between 110V and 220V, and thus the peak value of the maximum DC pulsating voltage is 220V and the peak value of the minimum DC pulsating voltage is 110V. According to rectifier circuit among the prior art, the maximum voltage value that required electric capacity bore is 220V, and according to the utility model discloses a rectifier circuit, the maximum voltage value that second electric capacity bore is 110V, has consequently reduced the volume of second electric capacity. In addition, although the withstand voltage value of the first capacitor is still 220V, the volume is small because the capacitance value is small.

To sum up, the utility model discloses a direct current pulsating voltage that filter circuit received is followed to the supply voltage that filter circuit produced in rectifier circuit in the time interval of the first time, and in the second time interval, supply voltage's numerical value is greater than the last time interval of the time's of the time supply voltage's of ending numerical value to reduce filter circuit's volume, and then reduced rectifier circuit's volume, improved the power density of AC/DC power.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A rectifier circuit, comprising:

2. The rectifier circuit according to claim 1, wherein the value of the supply voltage is less than or equal to the peak value of the minimum dc ripple voltage in the second time interval.

3. The rectifier circuit of claim 1 wherein said filter circuit is in a first mode of operation during a first portion of said first time interval and said filter circuit is in a second mode of operation during a second portion of said first time interval and said second time interval.

4. The rectifier circuit according to claim 3, wherein in the first operating mode, the filter circuit has a first capacitance value; in the second operating mode, the filter circuit has a second capacitance value, wherein the second capacitance value is greater than the first capacitance value.

5. The rectifier circuit according to claim 1, wherein the dc pulsed voltage energizes a subsequent circuit of the rectifier circuit in the first time interval.

6. The rectifier circuit according to claim 3, wherein a first portion of the first time interval starts when the DC ripple voltage rises to a second threshold value and ends when the DC ripple voltage falls to the first threshold value, and a second portion of the first time interval starts when the DC ripple voltage rises to the supply voltage and ends when the DC ripple voltage rises to the second threshold value.

7. The rectifier circuit according to claim 6, wherein the second time interval starts when the DC pulse voltage decreases to the first threshold value and ends when the DC pulse voltage increases to the supply voltage.

8. The rectifier circuit according to claim 7, wherein the second threshold is greater than the first threshold and less than or equal to a peak value of a minimum direct current ripple voltage.

9. The rectifier circuit according to claim 1, wherein the filter circuit comprises:

10. The rectifier circuit according to claim 9, wherein said first capacitor is connected in common parallel with said second capacitor during a second portion of said first time interval and said second time interval.

11. The rectifier circuit according to claim 9, wherein said second capacitor is disconnected from said first capacitor during a first portion of said first time interval.

12. The rectifier circuit according to claim 9, wherein the filter circuit further comprises:

13. The rectifier circuit according to claim 12, wherein when the dc pulse voltage decreases to a first threshold value, the first switch is controlled to conduct to connect the first capacitor in parallel at the input terminal of the filter circuit.

14. The rectifier circuit according to claim 12, wherein when the dc pulsating voltage rises to a second threshold, the first switch is controlled to be turned off to disconnect the first capacitor from the input terminal of the filter circuit.

15. The rectifier circuit according to claim 1, further comprising:

16. An AC/DC power supply, comprising:

the rectifier circuit of any one of claims 1-15; and