Power converter circuit protection system

Abstract

The invention discloses a power converter circuit protection system, which comprises an internal protection circuit module and an external protection circuit module, and is characterized in that the internal protection circuit module comprises an internal overcurrent protection circuit, an overheating protection circuit, an undervoltage protection circuit and an input overvoltage protection circuit; the external protection circuit comprises an external overcurrent protection circuit, a current-limiting protection circuit, an output overvoltage protection circuit and a soft start circuit, and the overcurrent protection circuit is used for limiting the limiting current of the power switch. The switching power supply converter protection circuit has the following advantages that the power supply chip adopts a current control mode, a compensation network is simple, and the reliability is high; an internal protection circuit module and an external protection circuit module do not need too complex peripheral circuits in field application, and a chip does not frequently switch on and switch off through an under-voltage protection circuit and an overvoltage protection circuit under the condition that input voltage fluctuates, so that normal operation of an internal control circuit is protected.

Description

Technical Field

[0001] The present invention relates to the technical field of power converter circuit protection, and in particular to a power converter circuit protection system. Background Art

[0002] At present, energy issues are important issues closely related to people's daily lives. Switching power supply technology is the main technology in today's power supply technology. It is widely used in various terminal devices and mobile electronic devices. Switching power supply refers specifically to a DC power supply in which power electronic devices work in a high-frequency switching state. The protection circuit is an indispensable and important part of the switching power supply. It can improve the reliability of the product and enable the power supply to work normally under harsh conditions. It plays a vital role in ensuring the system safety of the entire electronic equipment. However, the main reason for the failure of the module power supply within the expected effective time is the damage caused by external fault conditions, and the probability of failure in normal use is very low. Therefore, the important link to extend the life of the module power supply and improve the reliability of the system is to select products with perfect protection functions, that is, when the external circuit of the module power supply fails, the module power supply can automatically enter the protection state without permanent failure, which is an urgent problem to be solved. Therefore, a power converter circuit protection system is provided to solve the above problems. Summary of the invention

[0003] In order to solve the problems in the above background technology, the technical solution adopted by the present invention to solve the technical problems is: a power converter circuit protection system, which includes: an internal protection circuit module and an external protection circuit module, the internal protection circuit module includes an internal overcurrent protection circuit, an overheating protection circuit, an undervoltage protection circuit, and an input overvoltage protection circuit, the external protection circuit includes an external overcurrent protection circuit, a current limiting protection circuit, an output overvoltage protection circuit, and a soft start circuit, the overcurrent protection circuit is used to limit the power switch limit current, and the overheating protection circuit is used to detect the temperature of the power chip, and the output circuit is shut down if the maximum junction temperature is exceeded.

[0004] As a preferred technical solution of the present invention, the undervoltage protection circuit is used to prepare the chip before normal output; when the input voltage is too low or a power failure occurs suddenly, the internal power switch tube MOSFET is turned off.

[0005] As a preferred technical solution of the present invention, the input overvoltage protection circuit is used to force the MOSFET to turn off when the input voltage is too high, and the external overcurrent protection circuit is used to cut off the input circuit when the input current exceeds a specified value.

[0006] As a preferred technical solution of the present invention, the startup current limiting protection circuit is used to limit the instantaneous charging current of the input filter capacitor through a soft start power element, and the output overvoltage protection circuit is used to limit the output voltage through a voltage regulator tube.

[0007] As a preferred technical solution of the present invention, the soft start circuit is used to increase the output voltage smoothly and stably through the soft start capacitor when powered on.

[0008] As a preferred technical solution of the present invention, the undervoltage protection circuit includes a sampling resistor, a two-stage inverter and a stagnation comparator, the sampling resistor includes a resistor R1, a resistor R2, and a resistor R3, the resistors R1, R2, and R3 are connected in series, one end pin of the stagnation comparator is connected to the circuit between the resistor R1 and the resistor R2, and the two-stage inverter is electrically connected to one end pin of the stagnation comparator.

[0009] As a preferred technical solution of the present invention, the resistor R1 and the resistor R2 are used to sample the input voltage and compare it with an external reference voltage to determine whether the threshold voltage has been reached.

[0010] As a preferred technical solution of the present invention, the output signal of the two-stage inverter is used as a feedback control signal, and the threshold voltage is changed by turning on and off the NMOS tube MN1 connected in parallel with the resistor R3 to achieve a hysteresis effect. When the input voltage is lower than the reference voltage, the output signal is low level, MN1 is turned off, and the threshold voltage is;

[0011]

[0012] Among them, V TH- is the low level threshold voltage, V REF is the reference voltage, and R1, R2, and R3 are all sampling resistors.

[0013] As a preferred technical solution of the present invention, when the input voltage is higher than the reference voltage, the output signal is at a high level, MN1 is turned on, and the threshold voltage is;

[0014]

[0015] Among them, V TH+ is the high level threshold voltage.

[0016] As a preferred technical solution of the present invention, the input overvoltage protection circuit and the output overvoltage protection circuit both adopt an on-chip overvoltage protection circuit. The on-chip overvoltage protection circuit divides the output voltage through resistors R1 and R2 and then sends it to the comparator inside the chip through the feedback voltage input pin, and generates a control signal through a control logic circuit to control the conduction of the switch tube.

[0017] The present invention has the following advantages: the switching power converter protection circuit of the present invention has a power chip that adopts a current control mode, a simple compensation network, and does not require overly complex peripheral circuits in field applications through internal protection circuit modules and external protection circuit modules;

[0018] Through the undervoltage protection circuit and overvoltage protection circuit, when the input voltage fluctuates, the chip will not switch frequently to protect the normal operation of the internal control circuit. Compared with the traditional Zener diode, this circuit adopts an internal voltage stabilization interface circuit. When the input voltage is lower than the rated voltage, it can achieve a good follow-up effect on the input voltage. When the input voltage is higher than the rated voltage, it can stabilize the input voltage at a specific value to protect the normal operation of the internal control circuit.

[0019] The overvoltage protection circuit monitors the output voltage and promptly pulls the output voltage of the error amplifier to ground through the subsequent control logic circuit. Under the action of the low-end current limiting circuit, the chip quickly reduces the output voltage by charging the power supply through the load, thereby achieving the purpose of protecting the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the operating principle of the protection circuit of the preferred embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the operating principle of the undervoltage protection circuit of a preferred embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the operating principle of the overvoltage protection circuit of a preferred embodiment of the present invention;

[0023] Figure 4 It is a schematic diagram of a power chip circuit of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Many specific details are explained in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0025] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Please refer to Figure 1-Figure 4The present invention provides a power converter circuit protection system, comprising: an internal protection circuit module and an external protection circuit module. The internal protection circuit module comprises an internal overcurrent protection circuit, an overheat protection circuit, an undervoltage protection circuit, and an input overvoltage protection circuit. The external protection circuit comprises an external overcurrent protection circuit, a current limiting protection circuit, an output overvoltage protection circuit, and a soft start circuit. The overcurrent protection circuit is used to limit the limit current of the power switch. The overheat protection circuit is used to detect the temperature of the power chip. If the maximum junction temperature is exceeded, the output circuit is shut down.

[0027] Combination Figure 2 As shown, the undervoltage protection circuit is used to prepare the chip before normal output; when the input voltage is too low or a power failure occurs suddenly, the internal power switch tube MOSFET is turned off, the input overvoltage protection circuit is used to force the MOSFET to turn off when the input voltage is too high, the external overcurrent protection circuit is used to cut off the input circuit when the input current exceeds the specified value, the startup current limiting protection circuit is used to limit the instantaneous charging current of the input filter capacitor through the soft start power element, and the output overvoltage protection circuit is used to limit the output voltage through the voltage regulator tube. When the chip input voltage is lower than the minimum input voltage required for the normal operation of the chip, the chip is turned off to prevent abnormal operation of the chip. The function of the undervoltage protection circuit is to compare and judge the input voltage of the chip during the startup process of the chip, solve the startup difficulty caused by chip overload at startup, and provide control signals to the subsequent control logic part. When the input voltage of the chip is lower than the design index, it can give a control signal in time to control the opening and closing of the chip to protect the associated system from being affected.

[0028] Combination Figure 1As shown, the soft start circuit is used to make the output voltage increase smoothly and stably through the soft start capacitor when powered on, the undervoltage protection circuit includes a sampling resistor, a two-stage inverter and a stagnation comparator, the sampling resistor includes a resistor R1, a resistor R2, and a resistor R3, the resistors R1, R2, and R3 are connected in series, one end pin of the stagnation comparator is connected to the line between the resistor R1 and the resistor R2, the two-stage inverter is electrically connected to one end pin of the stagnation comparator, the resistor R1 and the resistor R2 are used to sample the input voltage and compare it with the external reference voltage to determine whether the threshold voltage has been reached, the undervoltage protection circuit reasonably sets the start threshold level of the input voltage, and the hysteresis effect generated by the hysteresis comparator reasonably sets the hysteresis interval, when the input voltage fluctuates, the chip will not frequently switch; in addition, by setting the hysteresis interval, it is prevented that the chip cannot start due to overload during startup, and the input voltage can be well followed to protect the normal operation of the internal control circuit. The overvoltage protection circuit monitors the output voltage by comparing the feedback signal of the output voltage with the reference voltage that has been level-shifted. When the output voltage is too high, the output voltage of the error amplifier is promptly pulled down to ground through the subsequent control logic circuit. Under the action of the low-end current limiting circuit, the chip quickly reduces the output voltage by charging the power supply through the load, thereby achieving the purpose of protecting the load.

[0029] Among them, the output signal of the two-stage inverter is used as a feedback control signal. By turning on and off the NMOS tube MN1 in parallel with the resistor R3, the threshold voltage is changed to achieve the hysteresis effect. When the input voltage is lower than the reference voltage, the output signal is low level, MN1 is turned off, and the threshold voltage is;

[0030]

[0031] Among them, V TH- is the low level threshold voltage, V REF is the reference voltage, and R1, R2, and R3 are all sampling resistors.

[0032] When the input voltage is higher than the reference voltage, the output signal is high, MN1 is turned on, and the threshold voltage is;

[0033]

[0034] Among them, V TH+ is the high level threshold voltage.

[0035] Both the input overvoltage protection circuit and the output overvoltage protection circuit use on-chip overvoltage protection circuits. The on-chip overvoltage protection circuit divides the output voltage through resistors R1 and R2, and then sends it to the comparator inside the chip through the feedback voltage input pin, and generates a control signal through the control logic circuit to control the conduction of the switch tube. The internal protection circuit module and the external protection circuit module are designed to meet the needs of the chip's application circuits, and to realize the multiplexing of input pins and enable pins under the requirements of peripheral circuits, that is, an independent external enable voltage is no longer required, and the level is reasonably converted so that it can meet the use requirements of the internal control module.

[0036] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0037] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power converter circuit protection system, characterized in that: include: An internal protection circuit module and an external protection circuit module, the internal protection circuit module includes an internal overcurrent protection circuit, an overheat protection circuit, an undervoltage protection circuit, and an input overvoltage protection circuit, the external protection circuit includes an external overcurrent protection circuit, a current limiting protection circuit, an output overvoltage protection circuit, and a soft start circuit, the overcurrent protection circuit is used to limit the power switch limit current, the overheat protection circuit is used to detect the power chip temperature, and the output circuit is shut down if the maximum junction temperature is exceeded.

2. A power converter circuit protection system as claimed in claim 1, characterized in that: The undervoltage protection circuit is used to prepare the chip for operation before normal output; when the input voltage is too low or a power failure occurs suddenly, the internal power switch tube MOSFET is turned off.

3. A power converter circuit protection system as claimed in claim 1, characterized in that: The input overvoltage protection circuit is used to force the MOSFET to turn off when the input voltage is too high, and the external overcurrent protection circuit is used to cut off the input circuit when the input current exceeds a specified value.

4. A power converter circuit protection system as claimed in claim 1, characterized in that: The startup current limiting protection circuit is used to limit the instantaneous charging current of the input filter capacitor through the soft start power element, and the output overvoltage protection circuit is used to limit the output voltage through the voltage regulator tube.

5. A power converter circuit protection system as claimed in claim 1, characterized in that: The soft start circuit is used to increase the output voltage smoothly and stably through the soft start capacitor when power is turned on.

6. A power converter circuit protection system as claimed in claim 1, characterized in that: The undervoltage protection circuit includes a sampling resistor, a two-stage inverter and a stagnation comparator. The sampling resistor includes a resistor R1, a resistor R2, and a resistor R3. The resistors R1, R2, and R3 are connected in series. One end pin of the stagnation comparator is connected to the line between the resistor R1 and the resistor R2. The two-stage inverter is electrically connected to one end pin of the stagnation comparator.

7. A power converter circuit protection system as claimed in claim 6, characterized in that: The resistor R1 and the resistor R2 are used to sample the input voltage and compare it with an external reference voltage to determine whether the threshold voltage has been reached.

8. A power converter circuit protection system as claimed in claim 6, characterized in that: The output signal of the two-stage inverter is used as a feedback control signal. By turning on and off the NMOS tube MN1 connected in parallel with the resistor R3, the threshold voltage is changed to achieve a hysteresis effect. When the input voltage is lower than the reference voltage, the output signal is low level, MN1 is turned off, and the threshold voltage is; Among them, V TH- is the low level threshold voltage, V REF is the reference voltage, and R1, R2, and R3 are all sampling resistors.

9. A power converter circuit protection system as claimed in claim 8, characterized in that: When the input voltage is higher than the reference voltage, the output signal is high level, MN1 is turned on, and the threshold voltage is; Among them, V TH+ is the high level threshold voltage.

10. The power converter circuit protection system according to claim 1, characterized in that: The input overvoltage protection circuit and the output overvoltage protection circuit both use an on-chip overvoltage protection circuit. The on-chip overvoltage protection circuit divides the output voltage through resistors R1 and R2, and then sends it to the comparator inside the chip through the feedback voltage input pin, and generates a control signal through a control logic circuit to control the conduction of the switch tube.

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