WO2019205940A1

WO2019205940A1 - Over-voltage protection circuit for switching power supply, switching power supply, and compressor

Info

Publication number: WO2019205940A1
Application number: PCT/CN2019/082096
Authority: WO
Inventors: 肖钊; 郑绪成; 任新杰
Original assignee: 广东美芝制冷设备有限公司
Priority date: 2018-04-25
Filing date: 2019-04-10
Publication date: 2019-10-31
Also published as: CN208299431U

Abstract

Provided are an over-voltage protection circuit for a switching power supply, the switching power supply, and a compressor. The over-voltage protection circuit comprises: a first voltage sampling module, with one end of the first voltage sampling module being connected to a bus of a switching power supply and the other end thereof being grounded; a switch module connected to the first voltage sampling module; a second voltage sampling module, with one end of the second voltage sampling module being connected to an auxiliary winding of the switching power supply and the other end thereof being grounded; and a comparison circuit, with an input end of the comparison circuit being connected to the second voltage sampling module and being connected to the first voltage sampling module by means of the switch module, and an output end of the comparison circuit being connected to a control apparatus of the switching power supply. According to the present application, where the protection pins of a switching power supply are limited, only one protection pin is used, double-voltage sampling is used, input and output double-over-voltage protection is realized, and thus the impact of grid voltage fluctuation and a power-on impulse voltage on the switching power supply is effectively reduced.

Description

Overvoltage protection circuit, switching power supply and compressor for switching power supply

This application claims the priority of the Chinese patent application filed on April 25, 2018, the Chinese Patent Office, the application number is 201820598250.3, and the invention is entitled "Overvoltage protection circuit for switching power supply, switching power supply and compressor". The citations are incorporated herein by reference.

Technical field

The present application relates to the field of analog integrated circuit technology, and in particular to an overvoltage protection circuit for a switching power supply, a switching power supply, and a compressor.

Background technique

Switching power supplies are widely used in various consumer electronic products due to their small size and high efficiency. As an essential part of the power supply, switching power supplies use the energy storage of the switch to turn on and off and the inductor to control the duty cycle. The output of the voltage is divided into a step-down type and a step-up type switching power supply. When the switching power supply is operated, the voltage VDS on the switching tube is the sum of the bus voltage and the voltage reflected by the output reflected voltage and the leakage inductance.

At present, due to the different voltage fluctuations of various power grids and the influence of the power-on voltage, the switching tube of the switching power supply is often exposed by the voltage of the bus voltage, the output reflected voltage, and the leakage inductance. Therefore, it is necessary to add an input overvoltage. protection. However, most switching power supplies do not provide input overvoltage protection. Only the output voltage protection configuration port is provided. The chip protection pin resources are tight and cannot be combined with input overvoltage protection and output overvoltage protection.

Therefore, in the case of grid voltage fluctuations and the double impact of the power-on voltage on the switching power supply, and the switching power supply chip protection pin resources are tight, how to combine input over-voltage protection and output over-voltage protection has become an urgent technical problem to be solved. .

Summary of the invention

The present application is intended to address at least one of the technical problems existing in the related art or related art.

To this end, an aspect of the present application is to provide an overvoltage protection circuit for a switching power supply.

Another aspect of the present application is to propose a switching power supply.

Yet another aspect of the present application is to provide a compressor.

In view of this, the present application provides an overvoltage protection circuit for a switching power supply, comprising: a first voltage sampling module, one end of the first voltage sampling module is connected to a bus of the switching power supply, and the other end of the first voltage sampling module is grounded. a switch module connected to the first voltage sampling module; a second voltage sampling module, one end of the second voltage sampling module is connected to the auxiliary winding of the switching power supply, and the other end of the second voltage sampling module is grounded; the comparison circuit, the comparison circuit The input end is connected to the second voltage sampling module, and is connected to the first voltage sampling module through the switch module, and the output end of the comparison circuit is connected to the control device of the switching power supply; the comparison circuit compares the bus voltage with the first threshold Relationship, and/or by comparing the relationship between the auxiliary winding voltage collected by the second voltage sampling module and the second threshold, outputting a corresponding signal to cause the control device to turn off the pulse width modulation (Pulse Width Modulation) output of the switching power supply .

The overvoltage protection circuit of the switching power supply according to the present application includes a first voltage sampling module, a second voltage sampling module, a switch module, and a comparison circuit. When the bus voltage is higher than a set first threshold, the switch module is turned on, The sampling voltage of a voltage sampling module is sent to the comparison circuit through the switch module, and the comparison circuit outputs a corresponding signal to the control device of the switching power supply, thereby turning off the PWM output, thereby realizing input protection to the switching power supply switch tube; when the bus voltage is normal The switch module is cut off, and the sampling voltage of the second voltage sampling module is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. At this time, if the sampled auxiliary winding voltage is higher than the set second threshold, the auxiliary winding voltage is delivered to Comparing the circuit, the comparison circuit outputs a corresponding signal to the control device of the switching power supply, thereby turning off the PWM output, and protecting the peripheral circuit of the output side from burning out the component because the output voltage is too high, and exiting the protection when the output voltage is normal. In the case that the switching power supply protection pin is limited, only one protection pin is used, and double voltage sampling is adopted to realize double overvoltage protection of input and output, thereby effectively reducing grid voltage fluctuation and influence of power surge voltage on switching power supply. The failure rate of the switching power supply due to the overvoltage of the switching tube is reduced, and the reliability of the switching power supply is improved.

In the above technical solution, preferably, the switch module includes any one of the following: a diode, a triode, and a field effect transistor (Metal Oxide Semiconductor).

In this technical solution, those skilled in the art should understand that the switch module includes any one of the following: a diode, a triode, a MOS tube, but is not limited thereto. As long as the bus voltage is higher than the set threshold, the switch module can be turned on, so that the used bus voltage can be sent to the comparison circuit, so that the comparison circuit generates a corresponding signal and sends it to the control device of the switching power supply, and then Turn off the PWM output.

In any of the above technical solutions, preferably, the switch module is a diode, the anode of the diode is connected to the first voltage sampling module, and the cathode of the diode is respectively connected to the second voltage sampling module and the comparison circuit.

In the technical solution, the switch module is a diode. If the bus voltage is higher than the set bus voltage threshold, the diode is turned on, and the input voltage sampling voltage is sent to the comparison circuit through the diode, and the comparison circuit outputs a corresponding signal to the control device, and then The PWM output is cut off to protect the switching power supply switch tube; when the bus voltage is normal, the diode is turned off, and the output voltage sampling is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. Through the technical solution of the present application, under the condition that the switching power supply chip protects the pin resources, the input overvoltage protection and the output overvoltage protection are combined, thereby effectively reducing product development and production cost and reducing product volume.

In any one of the above aspects, preferably, the first voltage sampling module comprises at least: a first resistor and a second resistor, wherein the first resistor is connected in series with the second resistor, one end of the series is connected to the bus bar, and the other end is grounded.

In the technical solution, the first voltage sampling module samples the bus voltage through a voltage dividing circuit composed of the first resistor and the second resistor to prevent the first voltage sampling module from being burnt due to the excessive bus voltage, thereby improving the reliability of the protection circuit. It should be understood by those skilled in the art that the first voltage sampling module includes the first resistor and the second resistor, but is not limited thereto.

In any one of the above aspects, preferably, the first voltage sampling module further includes: a first capacitor, the first capacitor being connected in parallel with the second resistor.

In the technical solution, the first voltage sampling module further includes a first capacitor, and the first capacitor acts as a filter to make the bus sampling voltage smooth and smooth, and has a certain anti-surge impact effect, thereby further improving the reliability of the switching power supply. .

In any one of the above aspects, preferably, the second voltage sampling module comprises at least: a third resistor and a fourth resistor, wherein the third resistor is connected in series with the fourth resistor, one end of the series is connected to the auxiliary winding, and the other end is grounded .

In the technical solution, the second voltage sampling module samples the auxiliary winding voltage through a voltage dividing circuit composed of the third resistor and the fourth resistor, so as to prevent the second voltage sampling module from being burnt due to the excessive voltage of the auxiliary winding, thereby improving the reliability of the protection circuit. Sex. It should be understood by those skilled in the art that the second voltage sampling module includes the third resistor and the fourth resistor, but is not limited thereto.

In any one of the above aspects, preferably, the second voltage sampling module further includes: a second capacitor, the second capacitor being connected in parallel with the fourth resistor.

In the technical solution, the second voltage sampling module further includes a second capacitor, and the second capacitor acts as a filter to make the auxiliary winding voltage sampling voltage smooth and smooth, and has a certain anti-surge impact effect, further improving the switching power supply. reliability.

It should be noted that the bus voltage protection value (that is, the first threshold) is calculated by the first resistor, the second resistor, and the fourth resistor, and the output voltage protection value (that is, the second threshold) is determined by the third resistor and the fourth resistor. Calculated.

In any of the above aspects, preferably, the anode of the diode is connected between the first resistor and the second resistor; and the cathode of the diode is connected between the third resistor and the fourth resistor.

In the technical solution, the first voltage sampling module and the second voltage sampling module are connected by a diode. When the bus voltage is higher than the set bus voltage threshold, the diode is turned on, and the sampling voltage is sent to the comparison circuit of the switching power supply chip through the diode. Then, the PWM output is turned off to protect the switching power supply switch tube; when the bus voltage is normal, the diode is turned off, and the output voltage sampling is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. In the case that the switching power supply protection pin is limited, the first voltage sampling module and the second voltage sampling module use only one protection pin, and adopt double voltage sampling to realize double overvoltage protection of input and output.

The present application further provides a switching power supply comprising: the overvoltage protection circuit of the switching power supply according to any one of the above technical solutions.

According to the switching power supply of the present application, the overvoltage protection circuit of the switching power supply according to any one of the above technical solutions is adopted, and therefore all the beneficial effects of the overvoltage protection circuit of the switching power supply are not described herein.

The present application also provides a compressor comprising: an overvoltage protection circuit of a switching power supply according to any one of the above aspects; or a switching power supply as in the above technical solution.

According to the compressor of the present application, the overvoltage protection circuit of the switching power supply according to any one of the above aspects, or the switching power supply according to the above technical solution, and therefore the overvoltage protection circuit of the switching power supply or the switching power supply The beneficial effects will not be described again.

Additional aspects and advantages of the present application will become apparent in the description which follows.

DRAWINGS

The above and/or additional aspects and advantages of the present application will become apparent and readily understood from

1 shows a schematic diagram of an overvoltage protection circuit of a switching power supply according to an embodiment of the present application;

2 shows a circuit schematic of an overvoltage protection circuit of a switching power supply in accordance with an embodiment of the present application.

detailed description

The above objects, features and advantages of the present application will be more clearly understood from the following description of the appended claims. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to facilitate a full understanding of the application. However, the present application may also be practiced in other different ways than those described herein. Therefore, the scope of the present application is not limited by the specifics disclosed below. Limitations of the embodiments.

An overvoltage protection circuit for a switching power supply in accordance with some embodiments of the present application is described below with reference to FIGS.

In an embodiment of the present application, as shown in FIG. 1 and FIG. 2, the present application provides an overvoltage protection circuit for a switching power supply, comprising: a first voltage sampling module 10, one end of the first voltage sampling module 10 and The busbar of the switching power supply is connected, the other end of the first voltage sampling module 10 is grounded; the switch module is a diode D1, and is connected to the first voltage sampling module 10; the second voltage sampling module 20, one end of the second voltage sampling module 20 is The auxiliary winding of the switching power supply is connected, the other end of the second voltage sampling module 20 is grounded; the comparison circuit 30, the input end of the comparison circuit 30 is connected to the second voltage sampling module 20, and passes through the switch module and the first voltage sampling module 10 Connected, the output of the comparison circuit 30 is connected to the control device of the switching power supply; the comparison circuit 30 compares the relationship between the bus voltage and the first threshold, and/or by comparing the auxiliary winding voltage collected by the second voltage sampling module 20 with The relationship between the two thresholds outputs a corresponding signal to cause the control device to turn off the PWM output of the switching power supply.

The overvoltage protection circuit of the switching power supply provided by the present application comprises a first voltage sampling module 10, a second voltage sampling module 20, a diode D1 and a comparison circuit 30. When the bus voltage is higher than a set first threshold, the diode D1 leads The sampling voltage of the first voltage sampling module 10 is sent to the comparison circuit 30 through the diode D1, and the comparison circuit 30 outputs a corresponding signal to the control device of the switching power supply, thereby turning off the PWM output, thereby realizing the input protection of the switching power supply switch tube. When the bus voltage is normal, the diode D1 is turned off, and the sampling voltage of the second voltage sampling module 20 is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. At this time, if the sampled auxiliary winding voltage is higher than the set second The threshold value, the auxiliary winding voltage is sent to the comparison circuit 30, and the comparison circuit 30 outputs a corresponding signal to the control device of the switching power supply, thereby turning off the PWM output, and protecting the output side peripheral circuit from burning out components due to excessive output voltage, and output voltage When it is normal, exit protection. In the case that the switching power supply protection pin is limited, only one protection pin is used, and double voltage sampling is adopted to realize double overvoltage protection of input and output, thereby effectively reducing grid voltage fluctuation and influence of power surge voltage on switching power supply. The failure rate of the switching power supply due to the overvoltage of the switching tube is reduced, and the reliability of the switching power supply is improved.

In this embodiment, those skilled in the art should understand that the switch module can also be replaced by a triode or a MOS tube, but is not limited thereto. As long as the bus voltage is higher than the set threshold, the switch module can be turned on, so that the used bus voltage can be sent to the comparison circuit 30, so that the comparison circuit 30 generates a corresponding signal and sends it to the control device of the switching power supply. And then turn off the PWM output.

In an embodiment of the present application, preferably, the anode of the diode D1 is connected to the first voltage sampling module 10, and the cathode of the diode D1 is connected to the second voltage sampling module 20 and the comparison circuit 30, respectively.

In this embodiment, the switch module is diode D1. If the bus voltage is higher than the set bus voltage threshold, the diode D1 is turned on, the input voltage sampling voltage is sent to the comparison circuit 30 through the diode D1, and the comparison circuit 30 outputs a corresponding signal. The control device further turns off the PWM output to protect the switching power supply switch tube; when the bus voltage is normal, the diode D1 is turned off, and the output voltage sampling is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. Through the embodiment of the present application, when the switching power supply chip protects the pin resource, the input overvoltage protection and the output overvoltage protection are combined, thereby effectively reducing product development and production cost and reducing product volume.

In an embodiment of the present application, preferably, the first voltage sampling module 10 detects a bus voltage through a voltage dividing circuit composed of a first resistor R1 and a second resistor R2. The first resistor R1 is connected in series with the second resistor R2. One end is connected to the bus voltage and the other end is connected to the ground, and the first capacitor C1 is connected in parallel with the second resistor R2.

In this embodiment, the first voltage sampling module 10 samples the bus voltage through a voltage dividing circuit composed of the first resistor R1 and the second resistor R2, so that the first voltage sampling module 10 can be prevented from being burnt due to excessive bus voltage, thereby improving protection. Circuit reliability. The first capacitor acts as a filter to make the bus sample voltage smooth and smooth, and has a certain anti-surge impact effect, further improving the reliability of the switching power supply. It should be understood by those skilled in the art that the first voltage sampling module 10 includes the first resistor R1 and the second resistor R2, but is not limited thereto.

In an embodiment of the present application, preferably, the second voltage sampling module 20 detects the auxiliary winding voltage through a voltage dividing circuit composed of a third resistor R3 and a fourth resistor R4 connected in series, and the third resistor R3 is connected in series with the fourth resistor R4. One end is connected to the auxiliary winding, the other end is connected to the ground, and the second capacitor C2 is connected in parallel with the fourth resistor R4.

In this embodiment, the second voltage sampling module 20 samples the auxiliary winding voltage through a voltage dividing circuit composed of the third resistor R3 and the fourth resistor R4, so as to prevent the second voltage sampling module 20 from being burnt due to the auxiliary winding voltage being too high, thereby improving Protect the reliability of the circuit. The second capacitor acts as a filter to make the auxiliary winding voltage sampling voltage smooth and smooth, and has a certain anti-surge impact effect, further improving the reliability of the switching power supply. It should be understood by those skilled in the art that the second voltage sampling module 20 includes the third resistor R3 and the fourth resistor R4, but is not limited thereto.

In an embodiment of the present application, preferably, the anode of the diode D1 is connected to the series connection point of the first resistor R1 and the second resistor R2, and the cathode of the diode D1 is connected to the series connection point of the third resistor R3 and the fourth resistor R4. And connected to the protection pin of the switching power supply chip.

In this embodiment, the first voltage sampling module 10 and the second voltage sampling module 20 are connected through the diode D1. When the bus voltage is higher than the set bus voltage threshold, the diode D1 is turned on, and the sampling voltage is sent to the switch through the diode D1. The comparison circuit 30 of the power chip further turns off the PWM output to protect the switching power supply switch tube; when the bus voltage is normal, the diode D1 is turned off, and the output voltage sampling is not affected by the bus voltage sampling, and the output voltage protection can be normally performed. In the case that the switching power supply protection pin is limited, the first voltage sampling module 10 and the second voltage sampling module 20 use only one protection pin, and adopt dual voltage sampling to realize double overvoltage protection of input and output.

It should be noted that the bus voltage protection value is calculated by the first resistor R1, the second resistor R2, and the fourth resistor R4, and the output voltage protection value is calculated by the third resistor R3 and the fourth resistor R4.

In a second aspect of the present application, a switching power supply is provided, comprising: an overvoltage protection circuit of a switching power supply according to any of the above embodiments.

The switching power supply provided by the present application adopts the overvoltage protection circuit of the switching power supply according to any of the above embodiments, and therefore has all the beneficial effects of the overvoltage protection circuit of the switching power supply, and details are not described herein again.

A third aspect of the present application further provides a compressor comprising: an overvoltage protection circuit of a switching power supply according to any of the above embodiments; or a switching power supply as in the above embodiment.

The compressor provided by the present application adopts the overvoltage protection circuit of the switching power supply according to any of the above embodiments, or the switching power supply as in the above embodiment, and therefore has the overvoltage protection circuit of the switching power supply or the switching power supply. The beneficial effects will not be described again.

In the description of the present specification, the terms "first" and "second" are used for the purpose of description only, and are not to be construed as indicating or implying relative importance unless otherwise specifically defined and defined; the term "connected", "Installation", "fixation", etc. should be understood in a broad sense. For example, "connection" may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present application can be understood on a case-by-case basis.

In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in the present application. At least one embodiment or example. In the present specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

The above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and various changes and modifications may be made to the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application are intended to be included within the scope of the present application.

Claims

An overvoltage protection circuit for a switching power supply, comprising:

a first voltage sampling module, one end of the first voltage sampling module is connected to a bus bar of the switching power supply, and the other end of the first voltage sampling module is grounded;

a switch module connected to the first voltage sampling module;

a second voltage sampling module, one end of the second voltage sampling module is connected to the auxiliary winding of the switching power supply, and the other end of the second voltage sampling module is grounded;

a comparison circuit, an input end of the comparison circuit is connected to the second voltage sampling module, and is connected to the first voltage sampling module through the switch module, an output end of the comparison circuit and the switching power supply Control devices are connected;

The comparison circuit outputs a corresponding signal by comparing a relationship between the bus voltage and a first threshold, and/or by comparing a relationship between an auxiliary winding voltage collected by the second voltage sampling module and a second threshold, so that the comparison circuit The control device turns off the pulse width modulated output of the switching power supply.
The overvoltage protection circuit of the switching power supply according to claim 1, wherein

The switch module includes any one of the following: a diode, a triode, and a field effect transistor.
An overvoltage protection circuit for a switching power supply according to claim 2, wherein

The switch module is a diode, an anode of the diode is connected to the first voltage sampling module, and a cathode of the diode is respectively connected to the second voltage sampling module and the comparison circuit.
The overvoltage protection circuit of the switching power supply of claim 3, wherein the first voltage sampling module comprises at least: a first resistor and a second resistor;

The first resistor is connected in series with the second resistor, and one end connected in series is connected to the bus bar, and the other end is grounded.
The overvoltage protection circuit of the switching power supply of claim 4, wherein the first voltage sampling module further comprises:

a first capacitor, the first capacitor being in parallel with the second resistor.
The overvoltage protection circuit of the switching power supply according to claim 4 or 5, wherein the second voltage sampling module comprises at least: a third resistor and a fourth resistor;

The third resistor is connected in series with the fourth resistor, and one end connected in series is connected to the auxiliary winding, and the other end is grounded.
The overvoltage protection circuit of the switching power supply of claim 6, wherein the second voltage sampling module further comprises:

a second capacitor, the second capacitor being in parallel with the fourth resistor.
An overvoltage protection circuit for a switching power supply according to claim 6, wherein

An anode of the diode is connected between the first resistor and the second resistor;

A cathode of the diode is coupled between the third resistor and the fourth resistor.
A switching power supply comprising: the overvoltage protection circuit of the switching power supply according to any one of claims 1 to 8.
A compressor comprising:

An overvoltage protection circuit for a switching power supply according to any one of claims 1 to 8; or

A switching power supply as claimed in claim 9.