CN108337768B

CN108337768B - Double-protection PFC constant current driving power supply circuit and control method

Info

Publication number: CN108337768B
Application number: CN201711457620.8A
Authority: CN
Inventors: 倪峰; 陆亚丽
Original assignee: Ningbo Lae Electronic Co ltd
Current assignee: Ningbo Lae Electronic Co ltd
Priority date: 2017-12-28
Filing date: 2017-12-28
Publication date: 2020-10-16
Anticipated expiration: 2037-12-28
Also published as: CN108337768A

Abstract

The invention discloses a double-protection PFC constant current driving power supply circuit and a control method, which comprises an alternating current input rectifying and filtering unit, a PFC power factor correction unit, a high-frequency transformer, an output filtering unit and an output unit, wherein the PFC power factor correction unit is connected with the high-frequency transformer through a field effect tube, the output of the output filtering unit is connected with the output unit through a fourth inductor, the output filtering unit is connected with the PFC power factor correction unit through a constant current output sampling unit, once overcurrent is output, a signal is immediately sent to the PFC power factor correction unit, the output current is finally controlled to be in a constant current state, and the output unit feeds back an output signal to a secondary protection circuit to reduce the voltage of a PFC power factor regulation chip to stop working. The circuit realizes a multi-stage protection function, is more stable, and is stable due to the fact that the capacitor, the inductor and the switch diode are arranged in the process of outputting and filtering, and the influence of ripples on sampling signals is eliminated.

Description

Double-protection PFC constant current driving power supply circuit and control method

Technical Field

The invention relates to an LED power circuit, in particular to a double-protection PFC constant current driving power circuit and a control method.

Background

The LED lamp is an electroluminescent semiconductor material chip, silver glue or white glue is solidified on the support, then the chip and the circuit board are connected through silver wires or gold wires, the periphery of the chip and the circuit board is sealed through epoxy resin, the effect of protecting an internal core wire is achieved, and finally the shell is installed, so that the anti-seismic performance of the LED lamp is good. The inherent characteristics of LEDs determine that they are the most desirable light sources to replace traditional light sources, and have a wide range of applications. The LED lamp has the following advantages: the volume is small; the power consumption is low, the power consumption of the LED is quite low, and generally, the working voltage of the LED is 2-3.6V. The working current is 0.02-0.03A. That is to say: the electric energy consumed by the device does not exceed 0.1W; the service life of the LED is long, and under proper current and voltage, the service life of the LED can reach 10 ten thousand hours; the LED lamp has high brightness and low heat, and the heat productivity of the LED lamp is much lower than that of a common lighting lamp by using a cold light emitting technology; in order to make a Light Emitting Diode (LED) or a lamp string group consisting of LEDs operate stably and reliably in the prior art, a two-stage PFC driving power circuit is usually adopted to ensure high power factor, low input current harmonic content, and optimal design of a DC/DC converter, but the current PFC driving power circuit has a relatively complex structure, and cannot ensure normal operation once a driving chip or an output feedback chip fails, so that how to ensure that the whole circuit needs to be in a safe state is particularly important.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provide a double-protection PFC constant current driving power supply circuit which is simple in structure and realizes bidirectional protection and a control method.

In order to achieve the above object, the invention provides a dual-protection PFC constant current driving power circuit, which includes an ac input rectifying and filtering unit, a PFC power factor correction unit, a high frequency transformer T1, an output filtering unit, and an output unit, wherein the PFC power factor correction unit is connected to a peripheral circuit through a PFC power factor adjustment chip U1 and connected to the high frequency transformer T1 through a field effect transistor Q1, an output of the output filtering unit is connected to the output unit through a fourth inductor L4, an output terminal of the output filtering unit is connected to the PFC power factor correction unit through a constant current output sampling unit, once an overcurrent is output, a signal is immediately sent to the PFC power factor correction unit to finally control an output current to be in a constant current state, the output unit feeds the output signal back to a power supply terminal of the PFC power factor adjustment chip U1 through a secondary protection circuit to control the output current to be stable, the secondary protection circuit comprises a first linear optocoupler U4, a sixteenth A resistor R16A, a sixteenth B resistor R16B, a sixteenth C resistor R16C, a sixteenth D resistor R16D and a third triode Q3, wherein one end of the sixteenth D resistor R16D is connected with the positive electrode Vo + of the output unit, the other end of the sixteenth D resistor R16D is connected with the positive electrode of the light emitting diode of the first linear optocoupler U4, the negative electrode of the light emitting diode of the first linear optocoupler U4 is connected with the negative electrode Vo-of the output unit, a first capacitor C111 is connected between the two output ends of the first linear optocoupler U4, one end of the first capacitor C111 is connected with the base of the third triode Q3, the other end of the first capacitor C111 is grounded, the collector of the third triode Q3 is connected with the collector of the PFC power factor adjusting chip U1 through the sixteenth B resistor R16B, and the sixteenth A resistor R16A is connected between the collector of the base of the third triode Q3, the emitter of the third triode Q3 is grounded, and a sixteenth C resistor R16C is connected between the base of the third triode Q3 and ground.

Further, in order to make the circuit more stable and the constant current effect better, the specific circuit connection structure of the PFC power factor adjustment chip U1 and the peripheral circuit is as follows:

the model of the PFC power factor adjusting chip U1 is L6562, a GD pin of the PFC power factor adjusting chip U1 is connected to a G pin of the fet Q1 through a seventeenth resistor R17, an S pin of the fet Q1 is grounded through a twentieth resistor R20, a GS terminal of the PFC power factor adjusting chip U1 is connected to an S pin of the fet Q1 through a nineteenth resistor R19, an eighteenth resistor R18 is connected between a common terminal of the S pin of the fet Q1 and the nineteenth resistor R19 and the G pin of the fet Q1, a seventeenth capacitor C17 is connected between the GS terminal of the PFC power factor adjusting chip U1 and the ground, a common terminal of the seventeenth capacitor C17 and the nineteenth resistor R19 is connected to the positive output terminal E of the input rectifying and filtering unit 1 through a seventeenth resistor R50, a seventeenth capacitor C16 is connected in parallel to the seventeenth resistor R17 and the positive terminal of the PFC power factor adjusting chip Q1, the ZCD end of the PFC power factor regulation chip U1 is connected with the pin 6 of a high-frequency transformer T1 through a sixteenth D resistor R16, the pin D of the field-effect tube Q1 is connected with the pin 3 of a high-frequency transformer T1, a thirteenth capacitor C13 and an eighth resistor R8 which are connected in series are connected between the COMP pin of the PFC power factor regulation chip U1 and the INV pin of the PFC power factor regulation chip U1, a fourteenth capacitor C14 is connected in parallel to the thirteenth capacitor C13 and the eighth resistor R8, a ninth resistor R9 and a tenth resistor R10 are connected in series between the INV pin of the PFC power factor regulation chip U1 and the ground, an eighteenth capacitor C18 is connected in parallel to the tenth resistor R10, a common end of the tenth resistor R10 and the ninth resistor R9 is connected with the feedback end of the constant current output sampling unit 5, a MULT pin of the PFC power factor regulation chip U1 is connected with the positive pole output of the rectifying and filtering unit U1 through a third resistor R3 and a fourth resistor R8269556 which are connected in series, and a PFC power factor regulation chip U8653, A twelfth resistor R12 is grounded, a common end of a fourth diode D4 and a twelfth resistor R12 is connected with a pin 6 of the high-frequency transformer T1 through an eleventh resistor R11 and a second diode D2 which are connected in series, an anode of a second diode D2 is connected with a pin 6 of the high-frequency transformer T1, a cathode of a second diode D2 is also connected with a collector of a second NPN triode Q2 through a thirteenth resistor R13, an emitter of the second NPN triode Q2 is grounded through a third diode D3 and a third capacitor C3 which are connected in series, a base of the second NPN triode Q2 is grounded through a first voltage stabilizing diode ZD1, a second capacitor C2 is connected between a collector of the second NPN triode Q2 and the ground, a collector of the second NPN triode Q2 and a base of a second triode Q2 are connected with a fourteenth resistor R14, a first diode D1 and a fifteenth capacitor 15 are connected in series between a pin D1 and an output anode E of the input filter unit, two groups of branches which are connected in parallel by two resistors and then connected in series are connected in parallel on the fifteenth capacitor C15, a pin 1 of the high-frequency transformer T1 is connected with the output positive electrode end E of the input rectifying and filtering unit 1, a circuit formed by connecting a fifth resistor R5, an eleventh capacitor C11 and a second voltage regulator tube ZD4 in parallel is connected between the MULT pin of the PFC power factor adjusting chip U1 and the ground, the common terminal of the third diode D3 and the third capacitor C3 is connected with the supply voltage VCC1, and a pin 8 of the PFC power factor adjusting chip U1 is connected with the supply voltage VCC 1.

Further, the constant current output sampling unit 5 includes a dual feedback transport amplifier U5 with model number TSM103, a second linear optocoupler U2 and a peripheral circuit, a pin 1 of the dual feedback transport amplifier U5 is connected to one negative terminal of a twelfth sharing anode switch diode D12, another negative terminal of the twelfth sharing anode switch diode D12 is connected to a pin 7 of the dual feedback transport amplifier U5 through a fifteenth resistor R45, a positive terminal of the twelfth sharing anode switch diode D12 is connected to a negative terminal of a light emitting diode of the second linear optocoupler U2, a positive terminal of a light emitting diode of the second linear optocoupler 2 is connected to the supply voltage VCC2, a triode collector of the second linear optocoupler U2 is connected to the supply voltage VCC1, a triode emitter of the second linear optocoupler U2 is connected to common terminals of a tenth resistor R10 and a ninth resistor R9, a thirty-fourth resistor R34 and a twenty-fifth capacitor R25 are connected in series between a pin 2 of the dual feedback transport amplifier U5 and a pin 1 of the dual feedback transport amplifier U5, a voltage division circuit is connected between the pin 2 of the dual-feedback transport amplifier U5 and the positive terminal of the filter output in the output filter unit, the voltage division circuit comprises a thirty-first resistor R31 and a thirty-third resistor R33 which are connected in series between the output terminal in the output filter unit and the ground, and a thirty-second resistor R32 which is connected in parallel to the thirty-third resistor R33, the voltage on the thirty-third resistor R33 is obtained by dividing the voltage by the pin 2 of the dual-feedback transport amplifier U5, a forty-sixth resistor R46 is connected in series between the pin 3 of the dual-feedback transport amplifier U5 and the supply voltage VCC2, a thirty-ninth resistor R39 and a twenty-fourth resistor R24 are connected in series between the pin 5 of the dual-feedback transport amplifier U5 and the pin 3 of the dual-feedback transport amplifier U5, an eighth resistor R38 is connected between the common terminal of the thirty-sixth resistor R39 and the twenty-fourth resistor R24 and the ground, and a forty resistor R41 is connected between the pin 6 of the dual-feedback transport amplifier U5 and the negative terminal of the filter output, a twenty-sixth capacitor C26 and a forty-fourth resistor R40 are connected in series between the 6 pin of the dual-feedback transport amplifier U5 and the 7 pin of the dual-feedback transport amplifier U5, the 8 pin of the dual-feedback transport amplifier U5 is connected with a power supply voltage VCC2, and a twenty-eighth capacitor C28 is connected between the 3 pin of the dual-feedback transport amplifier U5 and the 4 pin of the dual-feedback transport amplifier U5.

Further, in order to make the circuit more stable, the output filter unit includes 4 filter capacitors E1 connected in parallel between the secondary output coils of the high frequency transformer T1, a forty-third resistor R43 is connected in parallel to the filter capacitor E1, the positive terminal of the filter capacitor E1 is connected to a thirty-first resistor R31, three switching diodes connected in parallel between the negative terminal of the filter capacitor E1 and the output terminal of the high frequency transformer T1, the positive terminals of the 3 switching diodes connected to the negative terminal of the filter capacitor E1, the negative terminals of the 3 switching diodes connected to the high frequency transformer T1, a branch formed by connecting two resistors in parallel and then connecting a capacitor in series, the positive and negative terminals of the filter capacitor E1 are connected to two input terminals of a fourth inductor L4, two output pins of the fourth inductor L4 are connected to the output unit 4, and a forty-second resistor R42 is connected between the negative terminal of the filter capacitor E1 and the fourth inductor L4, a forty-first resistor R41 is connected between the common end of the forty-second resistor R42 and the fourth inductor L4 and the 6 feet of the double-feedback transport amplifier U5.

The

pins

3, 6 and 7 of the high-frequency transformer T1 and the pin connected with the positive electrode end of the filter capacitor E1 are homonymous terminals.

The invention also discloses a control method of the double-protection PFC constant current driving power supply circuit, which specifically comprises the following steps:

s1, firstly, a constant current output sampling unit acquires a feedback signal of the output current of the output filtering unit in real time, the feedback signal is transmitted to a PFC power factor correction unit through a second linear optocoupler U2, the PFC power factor correction unit performs power factor correction according to the change of the output current, and finally, the output constant current is controlled;

and S2, performing secondary protection on the output unit through the secondary protection circuit in real time, wherein once the output is short-circuited, the output is 0, and the secondary protection circuit reduces the power supply voltage of the PFC power factor correction unit to enable the PFC power factor correction unit not to work so as to play a role in protection and prevent elements from being burnt out.

The invention obtains a double-protection PFC constant current driving power supply circuit and a control method, firstly, a constant current output sampling unit acquires a feedback signal of output current of an output filter unit in real time, the feedback signal is transmitted to a PFC power factor correction unit through a second linear optical coupler U2, the PFC power factor correction unit carries out power factor correction according to the change of the output current, and finally, the output constant current is controlled, then the output unit is protected by the secondary protection circuit in a secondary way, once the output is short-circuited, the output is 0, the secondary protection circuit reduces the power supply voltage of the PFC power factor correction unit at the moment, so that the PFC power factor correction unit does not work to play a role in protection, prevent elements from being burnt out, finally realize a multi-stage protection function and enable the circuit to be more stable, meanwhile, each capacitor, each inductor and each switching diode are arranged in the output filtering process, so that the circuit is stable, and the influence of ripples on sampling signals is eliminated.

Drawings

Fig. 1 is a schematic block diagram of a dual protection PFC constant current driving power circuit in the present embodiment;

fig. 2 is a schematic diagram of a dual-protection PFC constant current driving power circuit in the present embodiment, where the PFC power factor correction unit is absent and the constant current output sampling unit is present;

fig. 3 is a schematic diagram of the PFC power factor correction unit in the present embodiment;

fig. 4 is a schematic diagram of the constant current output sampling unit in the present embodiment.

In the figure: the device comprises an alternating current input rectifying and filtering unit 1, a PFC power factor correction unit 2, an output filtering unit 3, an output unit 4, a constant current output sampling unit 5, a secondary protection circuit 6 and a voltage division circuit 7.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

Example (b):

as shown in fig. 1 and fig. 2, the dual-protection PFC constant current driving power circuit provided by the present invention includes an ac input rectifying and filtering unit 1, a PFC power factor correction unit 2, a high frequency transformer T1, an output filtering unit 3 and an output unit 4, where the PFC power factor correction unit 2 is connected to a peripheral circuit through a PFC power factor adjusting chip U1 and connected to the high frequency transformer T1 through a field effect transistor Q1, an output of the output filtering unit 3 is connected to the output unit 4 through a fourth inductor L4, an output end of the output filtering unit 3 is connected to the PFC power factor correction unit 2 through a constant current output sampling unit 5, and once an overcurrent is output, the output filtering unit sends a signal to the PFC power factor correction unit 2 to control an output current to be in a constant current state, the output unit 4 feeds the output signal back to a power supply end of the PFC power factor adjusting chip U1 through a secondary protection circuit 6 to control the output current to be stable, the secondary protection circuit 6 comprises a first linear optocoupler U4, a sixteenth A resistor R16A, a sixteenth B resistor R16B, a sixteenth C resistor R16C, a sixteenth D resistor R16D and a third triode Q3, wherein one end of the sixteenth D resistor R16D is connected with the positive electrode Vo + of the output unit 4, the other end of the sixteenth D resistor R16D is connected with the positive electrode of the light emitting diode of the first linear optocoupler U4, the negative electrode Vo-of the light emitting diode of the first linear optocoupler U4 is connected with the negative electrode Vo-of the output unit 4, a first capacitor C111 is connected between the two output ends of the first linear optocoupler U4, one end of the first capacitor C111 is connected with the base of the third triode Q3, the other end of the first capacitor C111 is grounded, the collector of the third triode Q3 is connected with the PFC factor adjusting chip U1 end through the sixteenth B resistor R16B, and a sixteenth A resistor R16A is connected between the collector of the third triode Q3, the emitter of the third triode Q3 is grounded, and a sixteenth C resistor R16C is connected between the base of the third triode Q3 and ground.

as shown in fig. 3, the PFC power factor adjusting chip U1 is of a model L6562, a GD pin of the PFC power factor adjusting chip U1 is connected to a G pin of the fet Q1 through a seventeenth resistor R17, an S pin of the fet Q1 is grounded through a twentieth resistor R20, a GS terminal of the PFC power factor adjusting chip U1 is connected to an S pin of the fet Q1 through a nineteenth resistor R19, an eighteenth resistor R18 is connected between a common terminal of the S pin of the fet Q1 and the nineteenth resistor R19 and the G pin of the fet Q1, a seventeenth capacitor C17 is connected between the GS terminal of the PFC power factor adjusting chip U1 and ground, a common terminal of the seventeenth capacitor C17 and the nineteenth resistor R19 is connected to the positive output terminal E of the input rectifying and filtering unit 1 through a fifty resistor fifty R50, a fourteenth capacitor C16, a positive terminal of the PFC power factor adjusting chip Q1 is connected to a cd 1, the ZCD end of the PFC power factor regulation chip U1 is connected with the pin 6 of a high-frequency transformer T1 through a sixteenth D resistor R16, the pin D of the field-effect tube Q1 is connected with the pin 3 of a high-frequency transformer T1, a thirteenth capacitor C13 and an eighth resistor R8 which are connected in series are connected between the COMP pin of the PFC power factor regulation chip U1 and the INV pin of the PFC power factor regulation chip U1, a fourteenth capacitor C14 is connected in parallel to the thirteenth capacitor C13 and the eighth resistor R8, a ninth resistor R9 and a tenth resistor R10 are connected in series between the INV pin of the PFC power factor regulation chip U1 and the ground, an eighteenth capacitor C18 is connected in parallel to the tenth resistor R10, the common end of the tenth resistor R10 and the ninth resistor R9 is connected with the feedback end of the constant current output sampling unit 5, the MULT pin of the PFC power factor regulation chip U1 is connected with the positive pole output of the rectifying and filtering unit U1 through a third resistor R3 and a fourth resistor R8269556 which are connected in series, and the positive pole of the PFC power factor regulation chip U4, A twelfth resistor R12 is grounded, a common end of a fourth diode D4 and a twelfth resistor R12 is connected with a pin 6 of the high-frequency transformer T1 through an eleventh resistor R11 and a second diode D2 which are connected in series, an anode of a second diode D2 is connected with a pin 6 of the high-frequency transformer T1, a cathode of a second diode D2 is also connected with a collector of a second NPN triode Q2 through a thirteenth resistor R13, an emitter of the second NPN triode Q2 is grounded through a third diode D3 and a third capacitor C3 which are connected in series, a base of the second NPN triode Q2 is grounded through a first voltage stabilizing diode ZD1, a second capacitor C2 is connected between a collector of the second NPN triode Q2 and the ground, a collector of the second NPN triode Q2 and a base of a second triode Q2 are connected with a fourteenth resistor R14, a first diode D1 and a fifteenth capacitor C15 are connected in series between a pin D1 and an output anode E of the input rectifying unit 1, two groups of branches which are connected in parallel by two resistors and then connected in series are connected in parallel on the fifteenth capacitor C15, a pin 1 of the high-frequency transformer T1 is connected with the output positive electrode end E of the input rectifying and filtering unit 1, a circuit formed by connecting a fifth resistor R5, an eleventh capacitor C11 and a second voltage regulator tube ZD4 in parallel is connected between the MULT pin of the PFC power factor adjusting chip U1 and the ground, the common terminal of the third diode D3 and the third capacitor C3 is connected with the supply voltage VCC1, and a pin 8 of the PFC power factor adjusting chip U1 is connected with the supply voltage VCC 1.

As shown in fig. 4, further, in order to make the circuit more stable, the constant current output sampling unit 5 includes a dual feedback transport amplifier U5 with model number TSM103, a second linear optocoupler U2 and a peripheral circuit, a pin 1 of the dual feedback transport amplifier U5 is connected to one negative terminal of a twelfth cascode switching diode D12, another negative terminal of the twelfth cascode switching diode D12 is connected to a pin 7 of the dual feedback transport amplifier U5 through a fifteenth resistor R45, a positive terminal of the twelfth cascode switching diode D12 is connected to a negative terminal of a light emitting diode of the second linear optocoupler U2, a positive terminal of the light emitting diode of the second linear optocoupler U2 is connected to a supply voltage VCC2, a collector of a triode of the second linear optocoupler U2 is connected to a supply voltage VCC1, an emitter of the triode of the second linear optocoupler U2 is connected to common terminals of a tenth resistor R10 and a ninth resistor R9, and a thirty resistor R34 and a fourth resistor R34 are connected in series between a pin 2 of the dual feedback transport amplifier U5 and a pin 1 of the dual feedback transport amplifier U5 Fifteen capacitors C25, a voltage dividing circuit 7 is connected between the 2 pin of the double feedback transport amplifier U5 and the positive terminal of the filter output in the output filter unit 3, the voltage dividing circuit 7 comprises a thirty-first resistor R31 and a thirty-third resistor R33 which are connected in series between the output terminal of the output filter unit 3 and the ground, and a thirty-second resistor R32 which is connected in parallel on the thirty-third resistor R33, the voltage on the thirty-third resistor R33 is obtained by dividing the voltage of the 2 pin of the double feedback transport amplifier U5, a forty-sixth resistor R46 is connected in series between the 3 pin of the double feedback transport amplifier U5 and the supply voltage VCC2, a thirty-ninth resistor R39 and a twenty-fourth resistor R24 are connected in series between the 5 pin of the double feedback transport amplifier U5 and the 3 pin of the double feedback transport amplifier U5, and a thirty-eighth resistor R38 is connected between the common terminal of the thirty-ninth resistor R39 and the twenty-fourth resistor R24 and the ground, a forty-first resistor R41 is connected between the 6 pin of the dual-feedback transport amplifier U5 and the negative end of the filter output in the output filter unit 3, a twenty-sixth capacitor C26 and a forty-first resistor R40 are connected in series between the 6 pin of the dual-feedback transport amplifier U5 and the 7 pin of the dual-feedback transport amplifier U5, an 8 pin of the dual-feedback transport amplifier U5 is connected with a power supply voltage VCC2, and a twenty-eighth capacitor C28 is connected between the 3 pin of the dual-feedback transport amplifier U5 and the 4 pin of the dual-feedback transport amplifier U5.

Furthermore, in order to make the circuit more stable, the output filter unit 3 includes 4 filter capacitors E1 connected in parallel between the secondary output coils of the high frequency transformer T1, a forty-third resistor R43 is connected in parallel to the filter capacitor E1, the positive terminal of the filter capacitor E1 is connected to a thirty-first resistor R31, three common anode switching diodes are connected in parallel between the negative terminal of the filter capacitor E1 and the output terminal of the high frequency transformer T1, the positive terminals of the 3 common anode switching diodes are connected to the negative terminal of the filter capacitor E1, the negative terminals of the 3 common anode switching diodes are connected to the high frequency transformer T1, a branch formed by connecting two resistors in parallel and then connecting a capacitor in series is further connected to the 3 common anode switching diodes, the positive terminal and the negative terminal of the filter capacitor E1 are connected to two input terminals of a fourth inductor L4, two output pins of the fourth inductor L4 are connected to the output unit 4, and a forty-second resistor R42 is connected between the negative terminal of the filter capacitor E1 and the fourth inductor L4, a forty-first resistor R41 is connected between the common end of the forty-second resistor R42 and the fourth inductor L4 and the 6 feet of the double-feedback transport amplifier U5.

The

pins

The embodiment also discloses a control method of the double-protection PFC constant current driving power circuit, which specifically comprises the following steps:

s1, firstly, a constant current output sampling unit 5 acquires a feedback signal of the output current of the output filtering unit 3 in real time, the feedback signal is transmitted to the PFC power factor correction unit 2 through a second linear optocoupler U2, and the PFC power factor correction unit 2 performs power factor correction according to the change of the output current and finally controls the output constant current;

and S2, performing secondary protection on the output unit 4 through the secondary protection circuit 6 in real time, wherein once the output is short-circuited, the output is 0, and at the moment, the secondary protection circuit 6 reduces the power supply voltage of the PFC power factor correction unit 2, so that the PFC power factor correction unit does not work to play a role in protection, and elements are prevented from being burnt.

The working principle is as follows: firstly, a constant current output sampling unit acquires a feedback signal of output current of an output filtering unit in real time, the feedback signal is transmitted to a PFC power factor correction unit through a second linear optocoupler U2, the PFC power factor correction unit performs power factor correction according to the change of the output current, the output constant current is finally controlled, then secondary protection is performed on the output unit through a secondary protection circuit, once the output short circuit occurs, the output is 0, the secondary protection circuit reduces the power supply voltage of the PFC power factor correction unit, the secondary protection circuit does not work so as to play a protection role, elements are prevented from being burnt out, finally, a multi-stage protection function is achieved, the circuit is more stable, meanwhile, each capacitor, each inductor and each switching diode are arranged in the output filtering process so that the circuit is stable, and the influence of ripples on the sampling signal is eliminated.

Claims

1. The utility model provides a PFC constant current drive power supply circuit of dual protection, includes AC input rectification filter unit (1), PFC power factor correction unit (2), high frequency transformer (T1), output filter unit (3) and output unit (4), characterized by: the PFC power factor correction unit (2) is connected with a peripheral circuit through a PFC power factor regulation chip (U1) and is connected with a high-frequency transformer (T1) through a field effect tube (Q1), the output of the output filtering unit (3) is connected with the output unit (4) through a fourth inductor (L4), the output end of the output filtering unit (3) is connected with the PFC power factor correction unit (2) through a constant current output sampling unit (5), once the overcurrent is output, a signal is immediately sent to the PFC power factor correction unit (2) to finally control the output current to be in a constant current state, the output unit (4) feeds the output signal back to the power supply end of the PFC power factor regulation chip (U1) through a secondary protection circuit (6) to control the output current to be stable, and the secondary protection circuit (6) comprises a first linear optical coupler (U4), a sixteenth A resistor (R16A), A sixteenth B resistor (R16B), a sixteenth C resistor (R16C), a sixteenth D resistor (R16D) and a third triode (Q3), wherein one end of the sixteenth D resistor (R16D) is connected with the positive electrode (Vo +) of the output unit (4), the other end of the sixteenth D resistor (R16D) is connected with the positive electrode terminal of the light emitting diode of the first linear optocoupler (U4), the negative electrode terminal of the light emitting diode of the first linear optocoupler (U4) is connected with the negative electrode (Vo-) of the output unit (4), a first capacitor (C111) is connected between the two output ends of the first linear optocoupler (U4), one end of the first capacitor (C111) is connected with the base electrode of the third triode (Q3), the other end of the first capacitor (C111) is grounded, the collector electrode of the third triode (Q3) is connected with the VCC end of the PFC power factor adjusting chip (U1) through the sixteenth B resistor (R16B), and the collector electrode of the sixteenth resistor (Q3) is connected with the sixteenth R16A 16A), the emitter of the third triode (Q3) is grounded, a sixteenth C resistor (R16C) is connected between the base of the third triode (Q3) and the ground, and the specific circuit connection structure of the PFC power factor adjusting chip (U1) and a peripheral circuit is as follows: the PFC power factor adjusting chip (U1) is of a model L6562, a GD pin of a PFC power factor adjusting chip (U1) is connected with a G pin of a field-effect tube (Q1) through a seventeenth resistor (R17), an S pin of a field-effect tube (Q1) is grounded through a twentieth resistor (R20), a GS end of the PFC power factor adjusting chip (U1) is connected with an S pin of the field-effect tube (Q1) through a nineteenth resistor (R19), an eighteenth resistor (R18) is connected between a common end of the S pin of the field-effect tube (Q1) and the nineteenth resistor (R19) and the G pin of the field-effect tube (Q1), a seventeenth capacitor (C17) is connected between a GS end of the PFC power factor adjusting chip (U1) and the ground, a common end of the seventeenth capacitor (C17) and the nineteenth resistor (R19) is connected with an anode output end of an input rectifying and filtering unit (R461) through a fifty resistor (R50), and a fourteenth diode (14) is connected with a fourteenth resistor (R4642), a sixteenth capacitor (C16) is connected between the ZCD end of the PFC power factor adjusting chip (U1) and the ground, the ZCD end of the PFC power factor adjusting chip (U1) is connected with the 6 pin of the high-frequency transformer (T1) through a sixteenth resistor (R16), the D pin of the field effect tube (Q1) is connected with the 3 pin of the high-frequency transformer (T1), a COMP pin of the PFC power factor adjusting chip (U1) and an INV pin of the PFC power factor adjusting chip (U1) are connected with a thirteenth capacitor (C13) and an eighth resistor (R8) which are connected in series, a fourteenth capacitor (C14) is connected in parallel with the thirteenth capacitor C13) and the eighth resistor (R8), a ninth resistor (R9) and a tenth resistor (R10) are connected in series between the INV pin of the PFC power factor adjusting chip (U1) and the ground, a ninth feedback resistor (R18) is connected in parallel with the tenth feedback resistor (R10), and a common feedback output unit (675) of a sampling resistor (R9) which is connected with a tenth resistor (10), the MULT pin of the PFC power factor regulation chip (U1) is connected with the output positive terminal E of the input rectifying and filtering unit (1) through a third resistor (R3) and a fourth resistor (R4) which are connected in series, the INV pin of the PFC power factor regulation chip (U1) is grounded through a fourth diode (D4) and a twelfth resistor (R12) which are connected in series, the common end of the fourth diode (D4) and the twelfth resistor (R12) is connected with the 6 pin of the high-frequency transformer (T1) through an eleventh resistor (R11) and a second diode (D2) which are connected in series, the positive electrode of the second diode (D2) is connected with the 6 pin of the high-frequency transformer (T1), the negative electrode of the second diode (D2) is also connected with the collector electrode of a second NPN triode (Q2) through a thirteenth resistor (R13), the emitter electrode of the second NPN triode (Q2) is connected with the third diode (D3) and a third capacitor (C13) which is connected with the ground through a first diode (ZD 1), a second capacitor (C2) is connected between the collector of the second NPN triode (Q2) and the ground, a fourteenth resistor (R14) is connected between the collector of the second NPN triode (Q2) and the base of the second NPN triode (Q2), a first diode (D1) and a fifteenth capacitor (C15) are connected in series between the D pin of the field effect transistor (Q1) and the output positive end E of the input rectifying and filtering unit (1), two groups of branches which are respectively connected in parallel by two resistors and then connected in series are connected on the fifteenth capacitor (C15), the 1 pin of a high-frequency transformer (T1) is connected with the output positive end E of the input rectifying and filtering unit (1), a circuit formed by connecting a fifth resistor (R5), an eleventh capacitor (C11) and a second voltage regulator tube (ZD 4) in parallel between the MULT pin of the PFC power factor adjusting chip (U1) and the ground, and the common power supply voltage VCC1 of the third diode (D3) and the third capacitor (C3) is connected with a VCC1, an 8 pin of a PFC power factor adjusting chip (U1) is connected with a power supply voltage VCC1, the constant current output sampling unit (5) comprises a double-feedback transport amplifier (U5) with the model of TSM103, a second linear optocoupler (U2) and a peripheral circuit, a 1 pin of the double-feedback transport amplifier (U5) is connected with one negative terminal of a twelfth common anode switching diode (D12), the other negative terminal of the twelfth common anode switching diode (D12) is connected with a 7 pin of the double-feedback transport amplifier (U5) through a fifteenth resistor (R45), a positive terminal of a twelfth common anode switching diode (D12) is connected with a negative terminal of a light emitting diode of the second linear optocoupler (U2), a positive terminal of a light emitting diode of a second linear optocoupler (U2) is connected with the power supply voltage VCC2, a triode collector of the second linear optocoupler (U2) is connected with the power supply voltage VCC1, and a triode emitter of the second linear optocoupler (U2) is connected with a common terminal of a tenth resistor (R10) and a ninth resistor (R9), a thirty-fourth resistor (R34) and a twenty-fifth capacitor (C25) are connected in series between a pin 2 of the dual-feedback transport amplifier (U5) and a pin 1 of the dual-feedback transport amplifier (U5), a voltage dividing circuit (7) is connected between the pin 2 of the dual-feedback transport amplifier (U5) and the positive electrode end of the filter output in the output filter unit (3), the voltage dividing circuit (7) comprises a thirty-first resistor (R31) and a thirty-third resistor (R33) which are connected in series between the output end of the output filter unit (3) and the ground, and a thirty-second resistor (R32) which is connected in parallel to the thirty-third resistor (R33), the voltage division of the pin 2 of the dual-feedback transport amplifier (U5) obtains the voltage of the thirty-third resistor (R33), a forty-sixth resistor (R46) is connected in series between the pin 3 of the dual-feedback transport amplifier (U5) and the power supply voltage 2, and a forty-sixth resistor (R46) is connected in series between a pin 5 of the dual-feedback transport amplifier (U5) and a pin thirty- The power supply circuit comprises a nine resistor (R39) and a twenty-fourth resistor (R24), a thirty-eighth resistor (R38) is connected between the common end of the thirty-ninth resistor (R39) and the twenty-fourth resistor (R24) and the ground, a forty-first resistor (R41) is connected between the pin 6 of the double-feedback transport amplifier (U5) and the negative electrode end of the filter output in the output filter unit (3), a twenty-sixth capacitor (C26) and a forty-eighth resistor (R40) are connected between the pin 6 of the double-feedback transport amplifier (U5) and the pin 7 of the double-feedback transport amplifier (U5) in series, the pin 8 of the double-feedback transport amplifier (U5) is connected with the power supply voltage 2, and a twenty-eighth capacitor (C28) is connected between the pin 3 VCC of the double-feedback transport amplifier (U5) and the pin 4 of the double-feedback transport amplifier (U5).

2. The dual-protection PFC constant current driving power supply circuit according to claim 1, wherein: the output filter unit (3) comprises 4 filter capacitors (E1) connected in parallel between secondary output coils of a high-frequency transformer (T1), a forty-third resistor (R43) is connected in parallel to the filter capacitor (E1), the positive electrode end of the filter capacitor (E1) is connected with a thirty-first resistor (R31), three common anode switching diodes are connected in parallel between the negative electrode end of the filter capacitor (E1) and the output end of the high-frequency transformer (T1), the positive electrodes of the 3 common anode switching diodes are connected with the negative electrode end of the filter capacitor (E1), the negative electrodes of the 3 common anode switching diodes are connected with the high-frequency transformer (T1), a branch circuit formed by connecting two resistors in parallel and then connecting a capacitor in series is further connected in parallel to the 3 common anode switching diodes, the positive electrode and the negative electrode of the filter capacitor (E1) are connected with two input ends of a fourth inductor (L4), and two output pins of the fourth inductor (L4) are connected with the output unit (4), a forty-second resistor (R42) is connected between the negative electrode of the filter capacitor (E1) and the fourth inductor (L4), and a forty-first resistor (R41) is connected between the common end of the forty-second resistor (R42) and the fourth inductor (L4) and the 6 pin of the double-feedback transport amplifier (U5).

3. The dual-protection PFC constant current driving power supply circuit according to claim 2, wherein: the pins 3, 6 and 7 of the high-frequency transformer (T1) and the pin connected with the positive terminal of the filter capacitor (E1) are homonymous terminals.

4. A control method of a double-protection PFC constant current driving power circuit adopts any one of claims 1-3, and is characterized in that: the method specifically comprises the following steps:

s1, firstly, a constant current output sampling unit (5) acquires a feedback signal of the output current of the output filtering unit (3) in real time, the feedback signal is transmitted to the PFC power factor correction unit (2) through a second linear optical coupler (U2), and the PFC power factor correction unit (2) corrects the power factor according to the change of the output current and finally controls the output constant current;

and S2, performing secondary protection on the output unit (4) through the secondary protection circuit (6) in real time, wherein once the output is short-circuited, the output is 0, and at the moment, the secondary protection circuit (6) pulls down the power supply voltage of the PFC power factor correction unit (2) to enable the PFC power factor correction unit to work so as to play a protection role and prevent elements from being burnt.