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2019-09-14

PFC Bus Voltage Control Circuit

 

CN Application CN108304024A

Priority 2018-04-03 • Filing 2018-04-03 • Publication 2018-07-20

Abstract

The invention discloses a PFC bus voltage control circuit comprising an input end, a PFC controller and an output end and further comprising a control unit, wherein the control unit is arranged between the input end, the PFC controller and the output end. The control unit is configured to detect an input voltage and adjust a bus voltage according to the detected magnitude of the input voltage, wherein the control unit controls the bus voltage to decrease with the decrease of the input voltage when the input voltage is lower than a preset voltage value. According to the PFC bus voltage controlcircuit, the goal of adjusting bus voltage when the low voltage is input into the PFC circuit can be achieved, the problem that the voltage difference of the PFC circuit is relatively large due to theconstant output of the bus voltage when the low voltage is input is solved. Meanwhile, the decrease of the voltage difference of the PFC circuit means that the temperature rise of the PFC circuit issignificantly improved, which greatly enhances the reliability of a switching power supply circuit and improves the service life of a switching power supply.

CN108304024A

CN Application

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Priority date

2018-04-03

 

Family: CN (1)

Date App/Pub Number Status

2018-04-03 CN 201810286069

2018-07-20 CN108304024A Application

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Description

translated from Chinese

PFC control circuit bus voltage

FIELD

[0001] The present invention relates to a switching power supply, and more particularly, to a control circuit for a PFC bus voltage.

Background technique

[0002] Currently, the vast majority of the market in the form of electricity needed to DC electrical equipment, and therefore, needs to be converted to DC power mains, but after rectified by the mains, the power factor is low, in order to improve the power factor , usually a power factor correction circuit (power Factor correction, PFC). Power factor correction (PFC) technology can improve the efficiency of the mains power supply when the AC to DC converter, which can improve the power factor of the load side, can also reduce the input current harmonics. In the prior art, the switching power supply, LED driving power supply has power supply design using multiple techniques pFC, after rectified by the mains, through the PFC circuit is the DC bus voltage conversion constant output, and then supplied to the subsequent stage circuit topology LLC. Wherein, when the input voltage of the PFC circuit is a low voltage, after the PFC circuit constant output bus voltage will result in a large pressure differential problem PFC circuit, for example, when the input voltage of 90VAC, the DC value of the rectified voltage Shu is 28V, if the bus voltage output from the PFC circuit is a constant 400V, 272V the pressure; when the input voltage is 277VAC, DC voltage is the rectified 392V, since the bus voltage output from the PFC circuit is a constant 400V, the pressure poor 8V. It can be seen, the low input voltage will cause a large pressure differential problem PFC circuit, causing the temperature rise problem, however, in the power supply design, thermal design is a very important part, directly affects the power of life.

SUMMARY

[0003] The present invention solves the technical problem is to provide a PFC control circuit bus voltage, can achieve the purpose bus voltage follower regulator in the PFC circuit input low voltage and resolve the input low bus voltage constant output caused by the PFC circuit pressure big problem, since the temperature rise to avoid problems caused by large pressure PFC circuit.

[0004] To solve the above problems, a first aspect, the present invention provides a control circuit for a PFC bus voltage, comprising: an input terminal, and an output controller PFC, further comprising a control unit, said control means being arranged between said input terminal and an output terminal of the PFC controller, the control means for detecting an input voltage and detected according to the magnitude of the input voltage of the corresponding bus voltage regulator, wherein, when the input voltage is lower than a preset voltage value, the said control unit controls the bus voltage follows the input voltage decreases.

[0005] In the PFC control circuit of the bus voltage provided by the present invention, the control unit includes an input voltage detecting circuit, a control voltage follower circuit, a PFC control loop circuit and a bus voltage adjusting circuit; said input voltage detection circuit coupled to said input terminal for detecting an input voltage; ends of the PFC loop control circuit with the first pin is connected to the PFC controller and a second pin for preventing said first primer pin voltage fluctuates; end of the bus voltage regulating circuit connected to the first pin, the other end connected to said output terminal, according to the first pin and the control circuit adjusts the voltage follower bus voltage; the control voltage follower circuit while the input voltage detection circuit, the PFC control loop circuit and the voltage regulating circuit connected to the bus, for, when the input voltage of the input voltage detection circuit is lower than a preset when the voltage value and the PFC control loop circuit, and the bus voltage regulating circuit for controlling the ON phase of the bus voltage follows the input voltage decreases.

[0006] In the PFC control circuit of the bus voltage provided by the present invention, the input voltage detection circuit includes a first - resistor, a second resistor, a third resistor, a fourth resistor and a first diode, a first resistor after a second resistor, a third resistor and a fourth resistor connected in series between the input terminal and the ground terminal, the anode of the first diode connected between the third resistor and the fourth resistor, whose cathode is connected to the voltage follower circuit control.

[0007] In the PFC control circuit of the bus voltage provided by the present invention, the input voltage detection circuit further comprises a first capacitor, said first capacitor first end connected to the cathode of the diode, the other end ground.

[0008] In the PFC control circuit of the present invention, the bus voltage provided by the voltage follower circuit comprises a control transistor and a fifth resistor, the transistor and the control terminal of the input voltage detection circuit connected to an input terminal of the One end of said fifth resistor is connected to an output terminal and the first pin of the PFC controller is connected to the other end of the power supply terminal of the fifth resistor.

[0009] In the PFC control circuit of the present invention, the bus voltage provided by the voltage follower circuit further includes a second control diode, the anode of the second diode is connected to the control terminal, a cathode connected to power supply end.

[0010] In the PFC control circuit of the present invention to provide the bus voltage, said transistor is a PNP transistor.

After [0011] In the PFC control circuit bus voltage provided by the invention, the PFC control loop circuit includes a seventh resistor, a second capacitor and a third capacitor, and the seventh resistor in series with the second capacitor a third capacitor in parallel, a third capacitor having one end connected to the first pin and the other end connected to the second pin.

[0012] In the PFC control circuit of the bus voltage provided by the present invention, the bus voltage regulating circuit comprises an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor, the eighth resistor after a ninth resistor, a tenth resistor, and an eleventh resistor connected in series between the output terminal and a ground terminal, one end of the twelfth resistor is connected to the resistance between the eleventh and tenth resistor and connected to the first pin, and the other end is grounded.

[0013] In the PFC control circuit of the bus voltage provided by the present invention, the control circuit further comprises a fourth capacitor, said fourth capacitor is connected at one end to said output terminal, and ground.

[0014] Compared with the prior art, bus voltage control circuit for a PFC of the present invention provides, said circuit comprising an input terminal, and an output controller PFC, further comprising a control unit, said control means being arranged between said input terminal and an output terminal of the PFC controller, the control means for detecting an input voltage and detected according to the magnitude of the input voltage of the corresponding bus voltage regulator, wherein, when the input voltage is lower than a preset voltage value, the said control unit controls the bus voltage is reduced to follow the input voltage is lowered, so that object can be achieved following the bus voltage regulation in the low-voltage input of the PFC circuit, the bus voltage due to solve the constant low voltage output input PFC circuit caused by the relatively large pressure differential problems, while reducing the pressure of the PFC circuit means temperature PFC circuit has been significantly improved, greatly enhancing the reliability of the switching power supply circuit, improves the service life of the switching power supply.

[0015] the following description in conjunction with the accompanying drawings, the present invention will become apparent from these drawings to explain an embodiment of the present invention.

BRIEF DESCRIPTION

[0016] FIG. 1 is a block schematic diagram of a PFC control circuit of the bus voltage provided by the present invention;

[0017] FIG 2 is a specific circuit diagram of a PFC control circuit of the bus voltage provided by the present invention.

detailed description

[0018] The present invention in conjunction with the following drawings in the embodiments, the embodiments of the technical solution will be clearly and completely described in, the accompanying drawings in which like numerals represent like components assembly. Obviously, the embodiments described below are merely part of embodiments of the present invention rather than all embodiments. Based on the embodiments of the present invention, those of ordinary skill in the art to make all other embodiments without creative work obtained by, it falls within the scope of the present invention.

[0019] It should be appreciated that, when used in this specification and the appended claims, the terms "comprises" and "comprising" indicates that the described features, integers, steps, operations, elements and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components and / or the presence or addition of collection.

[0020] It should also be understood that the terminology used in this specification only and are not intended to limit the present invention for the purpose of describing particular embodiments. As used in the specification and the appended claims of the invention as used in the book, unless the context clearly dictates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0021] It will be further appreciated that, in this specification and the appended claims, the term "and / or" means that one item associated listed and any combination of one or more of all possible combinations, and comprising these combinations.

[0022] The voltage control circuit of a PFC of the present invention provides a bus 100 includes an input terminal 13, a PFC controller 12 and an output terminal 14, further comprising a control unit 11, the control unit 11 is provided at the input end 13, between the PFC controller 12 and an output 14 for detecting an input voltage and detected according to the magnitude of the input voltage of the corresponding bus voltage regulator, wherein, when the input voltage is lower than a preset voltage value, the control unit 11 controls the bus voltage follows the input voltage decreases. The PFC control circuit 100 of the bus voltage may be implemented following the object of the bus voltage regulation in the low-voltage input of the PFC circuit, to solve the problem due to the low input bus voltage caused by the PFC circuit constant output pressure relatively large, while, the pressure of the PFC circuit means a decrease of the temperature difference between the PFC circuit has been significantly improved, greatly enhancing the reliability of the switching power supply circuit, improves the service life of the switching power supply.

[0023] Referring to FIG. 1, which is a block schematic diagram of a PFC control circuit of the bus voltage provided by the present invention, the PFC control circuit 100 includes a bus voltage input terminal 13, a controller 12 and a PFC an output terminal 14, further comprising a control unit 11, the control unit 11 is provided between the input 13 and the PFC controller 12 and an output terminal end 14, for detecting an input voltage and depending on the size of the detected voltage corresponding to the input regulate the bus voltage, wherein, when the input voltage is lower than a preset voltage value, the control unit 11 controls the bus voltage follows the input voltage decreases. The control unit 11 includes an input voltage detecting circuit 111, a voltage follower control unit 112, a PFC control loop circuit 113 and a bus voltage regulating circuit 114; the input voltage detection circuit 111 and the input terminal 13 is connected to an output terminal of the voltage follower 112 is connected to the control circuit, for detecting an input voltage; the control voltage follower circuit 112 and the control circuit while the PFC power supply bus voltage the VCC terminal, the input voltage detection circuit 111, PFC control circuit 113 and the loop bus voltage regulating circuit 114 is connected to the input voltage when the voltage detection circuit 111 is lower than a preset voltage value inputted to the PFC control circuit 113 and the loop the bus voltage regulating circuit 114 turned on to control the bus voltage follows the input voltage is lowered to reduce; PFC ends of the loop control circuit 113 are respectively connected to the PFC controller and a first pin 12 of the second lead 2 is connected to the foot, for preventing the first pin 1 of the voltage fluctuates; the bus voltage regulating circuit 114 is connected to one end of the first lead 1, and the other end thereof 14 is connected to an output terminal for the first pin 1 of the voltage follower and the control circuit 112 according to the bus voltage regulation.

When [0024] In the above embodiment, when the input voltage of the input voltage detection circuit 111 is lower than a preset voltage value, i.e., the low voltage input of the voltage follower satisfying the condition control circuit 112 is turned on, the said voltage follower circuit 112 and the control loop of the PFC control circuit 113 and the bus voltage regulating circuit 114 turned on to control the output voltage of the bus 14 follows the input voltage is lowered to reduce; when the input voltage detection circuit 111 when the input voltage value is not lower than a preset voltage value, i.e., the input voltage is a high voltage or low voltage input does not satisfy the conditions for conducting the control voltage follower circuit 112, control circuit 112 of the voltage follower is turned off the PFC control circuit 113 and the loop bus 114 is coupled voltage regulating circuit 1 is connected to the first pin, the first pin is fixed voltage value, the bus voltage of the output terminal 14 It outputs a constant value. Embodiment of the present invention may be implemented following the object of the bus voltage regulation in the low-voltage input of the PFC circuit, to solve the problem due to the low input bus voltage caused by the constant output of the PFC circuit relatively large pressure, while, decrease in pressure of the PFC circuit means the temperature of the PFC circuit has been significantly improved, greatly enhancing the reliability of the switching power supply circuit, improves the service life of the switching power supply.

[0025] Referring to FIG. 2, FIG. 2 is a specific circuit diagram of a PFC control circuit of the bus voltage provided by the present invention. The PFC control circuit 100 includes a bus voltage input terminal 13, a PFC controller 12 and an output terminal 14, further comprising a control unit 11, the control unit 11 is provided at the input terminal 13, the PFC controller 12 and the output terminal 14 for detecting an input voltage and corresponding adjustment of the bus voltage in accordance with the detected magnitude of the input voltage, wherein, when the input voltage is lower than a preset voltage value, the control unit 11 controls the bus voltage follower input voltage decreases.

[0026] The control unit 11 includes an input voltage detecting circuit 111, a voltage follower control unit 112, a PFC control loop circuit 113 and a bus voltage regulating circuit 114. Wherein the input voltage detection circuit connected to the input 111 of the input terminal 13, an output terminal unit 112 is connected to the voltage follower control, for detecting the input voltage. In particular, the input voltage detection circuit 111 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first diode D1, the first resistor R1, second resistor R2, after the third resistor R3 and a fourth resistor R4 are connected in series between ground 13 and the input terminal COM, an anode of the first diode D1 is connected to the fourth resistor R4 and the third resistor R3 between a cathode connected to the voltage follower control circuit 112, the input voltage detection circuit 111 for all of the above-described detecting input voltage dividing resistors. In some possible embodiments, for example in the present embodiment, the input voltage detection circuit 111 further includes a first capacitor C1, is connected to the cathode end of the first capacitor C1 and the first diode D1, which other end, for filtering, i.e., for suppressing the fluctuation of the input voltage, so that the voltage follower control unit 112 to obtain a smooth and stable voltage.

[0027] The voltage follower control unit 112 simultaneously with the PFC power supply terminal VCC of the control circuit 100 of the bus voltage, the input voltage detection circuit 111, the PFC control circuit 113 and the loop bus voltage regulating circuit 114 connected to said input voltage when the voltage detection circuit 111 is lower than a preset voltage value inputted to the PFC control circuit 113 and the loop bus voltage regulating circuit 114 turned on to control the bus voltage follower said input voltage decreases. In particular, the control voltage follower circuit 112 comprises a transistor Q1 and a fifth resistor R5, a control terminal of the transistor Q1 as the control input of the voltage follower circuit 112 and the input voltage detection circuit 111 is connected to the input end of one end of the fifth resistor R5 is connected to an output terminal of the PFC circuit 113 is connected to the control loop and connected to the PFC controller 112 of the first pin, the other end of the fifth resistor R5, the power supply end of the VCC; the voltage follower circuit 112 for controlling when the input voltage of the input voltage detection circuit is lower than a preset voltage value, the transistor Q1 is turned on, the voltage follower circuit 112 and the PFC control loop control circuit 113 and the bus voltage regulating circuit 114 turned on to control the bus voltage follows the input voltage decreases. In some possible embodiments, for example in the present embodiment, the predetermined voltage level is determined by the power source terminal VCC and the fifth resistor. In some possible embodiments, the present example embodiment, the transistor Q1 is a PNP transistor, said PNP transistor base electrode as a control terminal of the transistor Q1, and its emitter as an input transistor Q1, its collector as an output terminal of the transistor Q1. Specifically, when the input voltage value of the input voltage detection circuit is not lower than a preset voltage value, i.e., the base voltage is greater than the voltage value of the power supply terminal VCC, and the transistor Q1 is turned off, the the control unit 112 of the voltage follower loop with the PFC control circuit 113 and the bus voltage regulating circuit 114 is disconnected, the PFC control circuit 113 and the loop bus 114 is connected to the voltage regulating circuit to control the output bus voltage value constant ; when the voltage value of the input voltage detection circuit is lower than a preset voltage value of the input, i.e., the base voltage less than the voltage value of the power supply terminal VCC, and the transistor Q1 is turned on, the following control voltage unit 112 of the PFC control circuit 113 and the loop bus voltage regulating circuit 114 is turned on, so as to control the bus voltage follow the input voltage decreases. In some possible embodiments, the present example embodiment, the control voltage follower circuit 112 further includes a second diode D2, the anode of the second diode D2 is connected with the control terminal, a cathode connected to power supply terminal VCC, for clamping. In other possible embodiments, for example according to the present embodiment, the control voltage follower circuit 112 further comprises a sixth resistor R6, one end of the sixth resistor R6 is connected to the anode of the second diode D2, which end of the other end of the COM.

[0028] The PFC loop control circuit 113 simultaneously with the PFC controller 12, the voltage follower circuit control bus 112, and to suppress the voltage regulating circuit 114 is connected to the first pin voltage fluctuates , fixed to the potential of the first pin. In particular, the PFC loop control circuit 113 includes a seventh resistor R7, a second capacitor C2 and the third capacitor C3, the seventh resistor R7 and the second capacitor C2 in series with the third capacitor C3 in parallel the third capacitor C3 is connected to the first end of the pin 1 and the transistor Q1 is connected to an output terminal and an input terminal of the bus voltage regulating circuit 114, and the other end connected to the second pin 2 . In some possible embodiments, the present example embodiment, the PFC controller chip control TDA4S63 I2 is the TDA4863 chip has eight pins, including pin INV, C0MP pin, the MULT pin, the CS pin , VCC pin, OUT pin, GND pin, ZCD pin. Wherein the first pin INV pin, said second pin is C0MP pin.

[0029] The bus voltage regulating circuit 114 thousand and 1 simultaneously with the PFC control circuit of the bus voltage of the COM terminal, an output terminal 14, the voltage follower circuit 112 and the PFC control loop 113 is connected to the control circuit, according to the first pin and a voltage value of the voltage follower circuit 112 control the bus voltage regulation. In particular, the bus voltage regulating circuit comprises an eighth resistance RS, the ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a twelfth resistor R12, the eighth resistor R8, a ninth resistor R9, a first after ten eleventh resistor R10 and resistor R11 connected in series between the ground terminal 14 and the output terminal COM, one end of the twelfth resistor R12 is connected to the eleventh resistor R11 and the resistor R10 of the tenth 1 between the first pin and the other end thereof is connected to the ground COM.

[0030] In some possible embodiments, the PFC control circuit 100 further includes a bus voltage fourth capacitor C4, the end of the fourth capacitor and the output terminal 14 is connected to the other end, the means for filtering .

[0031] In the above embodiment, the design provides a control circuit for a bus voltage may be implemented at low PFC voltage follower circuit input PFC regulated bus voltage thousand and 1, a design of the control unit 11 may implement the pFc bus voltage control circuit 100 controls the input voltage to a low voltage bus voltage follows the input voltage is lowered to reduce a function, so as to solve problems due to low input voltage bus voltage caused by the PFC circuit constant output pressure relatively large, while reduced pressure means that the temperature rise of the PFC circuit PFC circuit has been significantly improved, greatly enhancing the reliability of the switching power supply circuit, improves the service life of the switching power supply.

[0032] Please continue to refer to FIG. 2, described in detail below a control circuit for a PFC operation principle of the present invention provides a bus voltage 100. The PFC control circuit 100 includes a bus voltage input terminal 13, a PFC controller 12 and an output terminal 14, further comprising a control unit 11, the control unit 11 is provided at the input terminal 13, the PFC controller 12 and the output terminal 14 for detecting an input voltage and an input voltage according to the magnitude corresponding to the detected bus voltage regulator, wherein, when the input voltage is lower than a preset voltage value, the control unit controls the voltage follower input bus voltage decreases. [0033] Input low level: when the voltage value of the input voltage detection circuit is lower than a preset voltage value of the input, i.e., the base voltage less than the voltage value of the power supply terminal VCC, and the transistor Q1 is turned through the voltage follower control unit 112 of the PFC control loop circuit, and the bus voltage II3 H4 phase adjusting circuit is turned on, the voltage follower and the first control voltage value of the fifth resistor R5 circuit 112 a voltage value adjusting pin 1 of the common bus voltage, the first pin 1 of the voltage value remains constant, the following control voltage on the voltage characteristics of the transistor Q1 in the circuit 112 follows the curve of the input voltage di voltage characteristic curve of the first diode detection circuit m varies, thereby controlling the bus voltage follows the input voltage decreases.

[0034] Input high: when the voltage value of the input voltage detection circuit is not lower than a predetermined input voltage, i.e. the voltage is greater than the base voltage value of the power supply terminal VCC, and the transistor Q1 turned off, the voltage follower control unit 112 does not operate, the control unit 112 and the voltage follower to the PFC control circuit 113 and the loop bus voltage regulating circuit 114 is disconnected, the PFC control circuit 113 and the loop said voltage regulating circuit 114 is connected to the bus, since the first pin 1 of the constant voltage of the PFC controller, the bus voltage regulated voltage eleventh resistor circuit 114 and the twelfth constant across the resistor, when when the resistance constant, the current bus voltage regulator circuit 114 unchanged, and therefore, the bus voltage 13 output from the output terminal remains unchanged.

[0035] The above embodiment in conjunction with the preferred embodiments of the present invention has been described, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications included within the spirit of the present invention.

 

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Priority And Related Applications

Priority Applications (1)

ApplicationPriority dateFiling dateTitle

CN 201810286069 2018-04-032018-04-03PFC bus voltage control circuit

Applications Claiming Priority (1)

ApplicationFiling dateTitle

CN 201810286069 2018-04-03PFC bus voltage control circuit

Legal Events

DateCodeTitleDescription

2018-07-20PB01

2018-08-14SE01


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