TWI631799B - System for providing input undervoltage and overvoltage protection for power converter - Google Patents

Abstract

The invention relates to a system for providing input undervoltage and overvoltage protection for a power converter. Provided is a system for providing input undervoltage and overvoltage protection for a power converter, including a line voltage-line current conversion module, a protection control logic module, a power-on reset and undervoltage lockout module, a switch driving module, and Power transistor. When the system is to be started, the switch driving module receives one or more test pulses. During one or more test pulses, the switch driving module receives an overvoltage signal and ANDs the first signal with the pulse control PWM signal to generate The voltage signal controls the transistor so that the system enters the trigger protection mode, and receives an undervoltage signal and ANDs the second signal with the PWM signal to generate an undervoltage signal to control the transistor so that the system enters the trigger protection mode.

Description

System for providing input undervoltage and overvoltage protection for power converter

The invention provides a system and method for providing input undervoltage and overvoltage protection for a power converter.

Power converters are widely used in consumer electronics devices such as portable devices. Power converters convert power from one form to another. As an example, the power source is converted from alternating current (AC) to direct current (DC), from DC to AC, from AC to AC, or from DC to DC. In addition, the power converter can switch power from one level to another. After the rectifier diode rectification filtering, the power converter generally converts the input AC voltage into a DC voltage.

However, in some countries and regions with underdeveloped power grids (e.g., India), the AC input voltage is quite unstable and fluctuates greatly from time to time (high voltage will instantly damage the power supply and low voltage will cause Resulting in unstable output voltage and larger ripple); therefore, it is quite necessary to add AC input undervoltage and overvoltage protection functions to the power converters used in these countries and regions.

In view of the problems described above, the present invention provides a system for providing input undervoltage and overvoltage protection for a power converter. Thus, for example, it is guaranteed that the power converter can work reliably in countries and regions where the power grid is less developed.

According to an aspect of the present disclosure, a system for providing input undervoltage and overvoltage protection for a power converter is provided, including a line voltage-line current conversion module, a protection control logic module, a power-on reset, and an undervoltage lockout module. , Switch driving module, and power transistor, in which the input of the line voltage-line current conversion module is coupled to the input voltage, and the output and protection control logic mode The inputs of the group are coupled and configured to convert the input voltage to line current; where the collector of the power transistor is connected to the input voltage via the primary winding of the transformer and to the ground via the sampling resistor; where the control logic module is protected The output of is coupled to the input of the switch drive module and is configured to: once the line current is sensed to become greater than the overvoltage protection threshold current, an overvoltage signal is generated to turn off the power transistor, and once the line is sensed When the current becomes less than the undervoltage protection threshold current, an undervoltage signal is generated to turn off the power transistor; and the input of the switch driving module and the output of the protection control logic module and the output of the power-on reset and undervoltage lockout module The coupling, the output is coupled to the base of the power transistor, and is configured such that when the system is to be started from the self-recovery mode after the power transistor is turned off, the switch driving module receives one or more test pulses, and During one or more test pulses, the switch driving module receives the overvoltage signal and compares the overvoltage signal with a pulse control PWM (Pulse Width Modulation) signal. Generating a switch signal so that the system enters the transistor to trigger the protection mode, and receives the signal and undervoltage undervoltage signal phase PWM signal to generate a switch signal to the transistor that triggers the system into protected mode.

According to another aspect of the present disclosure, a power converter including an undervoltage and an overvoltage protection system according to the present disclosure is provided.

The system according to the embodiment of the present application provides undervoltage and overvoltage protection for the power converter. Depending on the embodiment, one or more benefits may also be obtained. These benefits, as well as various additional objects, features, and advantages of the present invention can be fully understood with reference to the following detailed description and accompanying drawings.

100‧‧‧undervoltage and overvoltage protection system

110‧‧‧line voltage-line current conversion module

120‧‧‧ Protection Control Logic Module

130‧‧‧ Power-on reset and undervoltage lockout module

140‧‧‧Switch drive module

150‧‧‧ Power Transistor

160‧‧‧ Rectification Filter Module

N _p ‧‧‧ number of winding turns

V _DD ‧‧‧node

AC‧‧‧AC Power

DC‧‧‧DC Power Supply

T1‧‧‧Transformer

Rs‧‧‧Sampling resistor

R _start ‧‧‧start resistor

V _bulk ‧‧‧line voltage

I _line ‧‧‧line current

N _aux ‧‧‧ turns of auxiliary winding

I _BASE ‧‧‧Base output current signal

I _LBO ‧‧‧Under-voltage protection threshold current

V _aux ‧‧‧Voltage on auxiliary winding

I _lovp ‧‧‧ Overvoltage protection threshold current

PWM‧‧‧pulse control signal

D1‧‧‧ secondary rectifier diode

D2‧‧‧Auxiliary winding rectifier diode

Nsec‧‧‧Transformer secondary side turns

BOVP_ST‧‧‧Protection control signal at startup

BOVP_NORM‧‧‧ Protects the control signal during normal operation

t1, t2, t3, t4, t5, t6, T _timer1 , T _timer2 ‧‧‧ time

201, 202, 203, 204, 205, 206, 207, 208, 209, 301, 302, 303, 304, 305, 306, 307, 308, 309‧‧‧ waveform

LOVP‧‧‧ overvoltage signal

LBO‧‧‧undervoltage signal

BOVP_CTRL‧‧‧Protection signal

PWM_CTRL‧‧‧pulse signal

T _counter ‧‧‧pulse

R1, R2‧‧‧Feedback resistor

CLK‧‧‧ clock signal

POR‧‧‧ Power on reset signal

BASE‧‧‧base node

FB‧‧‧Feedback Node

Vo‧‧‧ output voltage

Hereinafter, the features, advantages, and technical effects of the exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Similar reference numerals in the drawings represent similar elements, wherein:

FIG. 1 is a block diagram illustrating an undervoltage and overvoltage protection system according to an embodiment of the present invention.

FIG. 2 is a simplified timing diagram illustrating the timing relationships of the control signals for the undervoltage and overvoltage protection systems of FIG. 1 in an embodiment.

Fig. 3 is a diagram showing each of the undervoltage and overvoltage protection systems used in Fig. 1 in another embodiment. A simplified timing diagram of the timing relationship of the control signals.

Features and exemplary embodiments of various aspects of the invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to a person skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely for providing a better understanding of the present invention by showing examples of the present invention. The invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, components and algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention.

FIG. 1 is a block diagram illustrating an undervoltage and overvoltage protection system 100 according to an embodiment of the present invention. This figure is only an example, and it should not unduly limit the scope of patent application. Those of ordinary skill in the art should understand many variations, substitutions, and modifications. As shown in FIG. 1, the undervoltage and overvoltage protection system 100 may include: a line voltage-line current conversion module 110, a protection control logic module 120, a power-on reset and undervoltage lockout module 130, and a switch driving module. 140. Power transistor 150. In addition, the system may further include a pulse generating module, a transformer T1, a rectifying and filtering module, a power transistor 150, and feedback voltage dividing resistors R1 and R2, CRs.

In one example, the power transistor 150 is a bipolar junction transistor. In another example, the power transistor 150 is a field-effect transistor (eg, a metal-oxide semiconductor field-effect transistor (MOSFET)). In yet another example, the power transistor 150 is an Insulated Gate Bipolar Transistor (IGBT). In various examples, the resistance values of the feedback voltage-dividing resistors R1 and R2 and the sampling resistor Rs can be set by those skilled in the art as needed.

As shown in FIG. 1, the input of the line voltage-line current conversion module 110 is coupled to the output of the rectification filter module 160, and the output is coupled to the input of the protection control logic module 120. Pick up. The input of the line voltage-line current conversion module 110 is also coupled between the feedback voltage dividing resistors R1 and R2. The output of the protection control logic module 120 is coupled to the output of the line voltage-line current conversion module 110, and the output is coupled to the input of the switch driving module 140. The input of the switch driving module 140 is coupled to the output of the protection control logic module 120 and the output of the power-on reset and undervoltage lockout module 130, and the output is coupled to the base of the power transistor 150. The base of the power transistor 150 is coupled to the output of the switch driving module 140, the collector is coupled to one end of the primary winding inductance of the transformer T1, and the emitter is coupled to one end of the sampling resistor Rs (resistor The other end of Rs is coupled to the ground signal). The series-connected feedback voltage dividing resistors R1 and R2 are coupled to the input of the line voltage-line current conversion module.

During the turn-on period of the power transistor 150, the line voltage-line current conversion module samples the line voltage V _bulk and converts the line voltage V _bulk into a line current I _line . During the turn-on period of the power transistor 150, the voltage V _aux on the auxiliary winding is a negative voltage, which is proportional to the line voltage V _bulk , and is specifically expressed as follows: Where N _aux represents the number of turns of the auxiliary winding and N _p represents the number of turns of the primary winding. Therefore, during the turn-on period of the power transistor 150, the line voltage I _line can be determined as follows: Among them, R ₁ represents the resistance value of the voltage dividing resistor on the feedback, and K represents the constant of the conversion coefficient from voltage to current.

After converting the line voltage V _bulk into the line current I _line , the line voltage-line current conversion module 110 sends the line current I _line to the protection control logic module 120. According to one embodiment, when the line current I _{line is} greater than the over-voltage protection threshold current (I _lovp ); the protection control logic module 120 determines that an over-voltage situation has occurred and locks the current state to generate a protection signal (BOVP_CTRL). The protection signal (BOVP_CTRL) and the pulse signal (PWM_CTRL) generated by the pulse generation circuit are ANDed to generate a switching signal (for example, a pulse width modulation PWM signal). The switch driving module 140 converts the PWM signal into a base output current signal (I _BASE ) to control the on and off of the power transistor 150.

According to another embodiment, when the line current I _{line is} less than the under-voltage protection threshold current (I _LBO ); the protection control logic module 120 determines that an under-voltage situation occurs and locks the current state to generate a protection signal (BOVP_CTRL). The protection signal (BOVP_CTRL) and the pulse signal (PWM_CTRL) generated by the pulse generation circuit are ANDed to generate a switching signal (for example, a pulse width modulation PWM signal). The switch driving module 140 converts the signal PWM into a base output current signal (I _BASE ) to control the on and off of the power transistor 150.

The system 100 may further include a rectification and filtering module 160. Thus according to one embodiment, when powered on, the system 100 receives an alternating current input voltage (eg, an AC input voltage). The AC input voltage is received by a rectification and filtering module 160 (for example, a full-wave rectification bridge), and the rectification and filtering module 160 then generates a rectified output current for subsequent operation of the system 100. The rectified output current generates a _bulk voltage V _bulk on a start resistor R _start connected to a node V _DD of the output of the rectification filter module 160. When the system is powered on, V _{DD is} charged through the start resistor R _start . When V _DD rises to the power-on reset voltage, the system starts to complete and works in normal mode.

FIG. 2 is a simplified timing diagram showing the timing relationship of the respective control signals for the under-voltage and over-voltage protection system 100 of FIG. 1. This figure is only an example, and it should not unduly limit the scope of patent application. Those of ordinary skill in the art should understand many variations, substitutions, and modifications. As shown in FIG. 2, waveform 201 represents a fixed overvoltage protection threshold current I _lovp , waveform 202 represents a time-varying line current I _line , and waveform 303 represents an overvoltage signal LOVP, and waveform 204 represents a protection signal BOVP_CTRL. In Figure 2, for example, t ₀ t ₁ <t ₂ t ₃ <t ₄ t ₅ t ₆ .

When the line current I _line (for example, at time t ₀ ) becomes greater than the over-voltage protection threshold current I _lovp (for example, as shown by waveform 202); the protection control logic module 120 determines that an over-voltage situation has occurred. After a certain time delay (for example, T _timer1 ), the trigger protection mode is entered, the power transistor 150 is turned off, and then the system 100 enters the self-recovery mode.

According to one embodiment, during the self-recovery mode, when the system 100 is about to start operating, first several pulses (T _counter ) are output. According to one embodiment, one pulse is output as a sensing pulse; in other embodiments, the sensing pulse may be generally no more than 10 pulses, such as 2, 3, etc. (for example, as shown in waveform 209).

During the sensing pulse (T _counter ), if the sensed line current I _{line is} greater than the over-voltage protection threshold current I _lovp, it immediately enters the self-recovery mode again. In other words, the system can generate only one pulse or a few pulses, for example less than 10 pulses. During the self-recovery mode, if no line current I _{line is} greater than the overvoltage protection threshold current I _lovp during the sensing pulse (T _counter ) period, the system will enter the exit protection mode and resume normal operation.

FIG. 3 is a simplified timing diagram illustrating the timing relationships of the control signals for the under-voltage and over-voltage protection system 100 of FIG. 1 in another embodiment. This figure is only an example, and it should not unduly limit the scope of patent application. Those of ordinary skill in the art should understand many variations, substitutions, and modifications. As shown in FIG. 3, waveform 301 represents a fixed under-voltage protection threshold current I _LBO , waveform 302 represents a line current I _line that changes with time, and waveform 303 represents an under-voltage signal LBO, and waveform 304 represents a protection signal BOVP_CTRL. In Figure 3, for example, t ₀ t ₁ <t ₂ t ₃ <t ₄ t ₅ t ₆ .

Similar to the situation in Figure 2, when the system 100 senses that the line current (I _line ) is less than the under-voltage protection threshold current (I _LBO ) during normal operation, the protection control logic module 120 determines that an under-voltage situation occurs. After a certain time delay (for example, T _timer2 ), the trigger protection mode is entered, the power transistor 150 is turned off, and then the system enters the self-recovery mode.

According to one embodiment, a number of pulses (T _counter ) are first output at the beginning of operation during the self-recovery mode. According to one embodiment, one pulse is output as the sensing pulse; in other embodiments, the sensing pulse may be generally no more than 10 pulses, such as 2, 3, etc. (for example, as shown in waveform 309).

If the line current I _{line is} less than the under-voltage protection threshold current I _LBO during the sensing pulse (eg, T _counter ), it immediately enters the self-recovery mode again. In other words, the system can generate only one pulse or a few pulses, for example less than 10 pulses. During the self-recovery period, if the line current I _{line is} less than the under-voltage protection threshold current I _LBO during the sensing pulse T _counter period, the system will enter the exit protection mode and resume normal operation.

The present invention may be implemented in other specific forms without departing from the spirit and essential characteristics thereof. For example, the algorithms described in particular embodiments may be modified without the system architecture departing from the basic spirit of the invention. Therefore, the current embodiment is considered in all aspects as exemplary rather than limiting, the scope of the present invention is defined by the scope of the attached patent application rather than the above description, and the meanings and equivalents falling within the scope of the patent application All changes within the scope of the substance are thus included in the scope of the present invention.

Some or all of the elements of the various embodiments of the invention, alone and / or in combination with at least another element, are one of one or more software elements, one or more hardware elements, and / or software and hardware elements Or multiple combinations to achieve. In another example, some or all of the elements of various embodiments of the present invention are implemented in one or more circuits alone and / or in combination with at least another element, such as in one or more analog circuits and / or Implemented in one or more digital circuits. In yet another example, various embodiments and / or examples of the present invention may be combined.

Although specific embodiments of the present invention have been described, those skilled in the art will appreciate that there are other embodiments equivalent to the described embodiments. Therefore, it will be understood that the present invention is not limited by the specific embodiments shown, but is limited only by the scope of patent application.

Claims (5)

A system for providing input undervoltage and overvoltage protection for a power converter includes a line voltage-line current conversion module, a protection control logic module, a power-on reset and undervoltage lockout module, a switch drive module, and a power circuit. A crystal, wherein the input of the line voltage-line current conversion module is coupled to the input voltage, the output is coupled to the input of the protection control logic module, and is configured to convert the input voltage to a line current; wherein The collector of the power transistor is connected to the input voltage via the primary winding of the transformer and to the ground via the sampling resistor; wherein the output of the protection control logic module is coupled to the input of the switch driving module and is configured To; once it is sensed that the line current becomes greater than the overvoltage protection threshold current, an overvoltage signal is generated to turn off the power transistor, and once it is sensed that the line current becomes less than the undervoltage protection threshold current Generating an undervoltage signal to turn off the power transistor; and wherein an input of the switch driving module and an output of the protection control logic module and the power-on The output of the constant voltage and undervoltage lockout modules is coupled, the output is coupled to the base of the power transistor, and is configured as a self-recovery mode when the system is to be turned off from the power transistor When starting, the switch driving module receives one or more test pulses. During the one or more test pulses, the switch driving module receives the overvoltage signal and controls the overvoltage signal and pulses. The PWM signal is ANDed to generate a switching signal to control the transistor so that the system enters a trigger protection mode, and to receive the undervoltage signal and AND the PWM signal to generate a switching signal to control a switching signal. The transistor to make the system enter a trigger protection mode; if the line current does not become greater than the over-voltage protection threshold current during the self-recovery mode, the system enters an exit protection mode and recovers Normal working state; if it is not sensed that the line current becomes smaller than the under-voltage protection threshold current during the self-recovery mode, the system enters the exit protection mode And resume normal working conditions. The system according to item 1 of the scope of patent application, further comprising a rectification and filtering module, which rectifies the input voltage and outputs the rectified and filtered voltage to the line voltage-line current conversion module. The system according to item 1 of the patent application scope, wherein the number of the one or more test pulses is not more than ten. The system according to item 3 of the scope of patent application, wherein the number of the one or more test pulses is two or three. A power converter including a system according to any one of claims 1 to 4 of the scope of patent application.