CN211183793U

CN211183793U - PFC control circuit

Info

Publication number: CN211183793U
Application number: CN201921629122.1U
Authority: CN
Inventors: 不公告发明人
Original assignee: Shanghai Hugong Electric Group Co Ltd
Current assignee: Shanghai Hugong Electric Group Co Ltd
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2020-08-04
Anticipated expiration: 2029-09-27

Abstract

The embodiment of the utility model discloses PFC control circuit, this PFC control circuit includes drive control circuit, segmentation voltage circuit and start control circuit, drive control circuit is used for detecting the signal of the signal adjustment drive signal output of end according to voltage, segmentation voltage circuit's output and drive control circuit's voltage detection end electric connection, segmentation voltage circuit is used for the signal according to the control end, the voltage that falls into two at least grades with the voltage of input is exported from the output, start control circuit's output and segmentation voltage circuit's control end electric connection, start control circuit is used for controlling the grade of the voltage of segmentation voltage circuit output according to the control signal of input. An embodiment of the utility model provides a PFC control circuit to realize that drive control circuit has the adaptation scope of great input grid voltage, can make PFC control circuit work at bigger voltage range.

Description

PFC control circuit

Technical Field

The embodiment of the utility model provides a relate to voltage control technique, especially relate to a PFC control circuit.

Background

With the wide application of the inverter type welding and cutting Power supply, the current distortion problem of the Power grid generated by the inverter Power supply is more prominent, and the current distortion problem can be effectively solved by an active PFC (Power Factor Correction) technology.

At present, many manufacturers in the field of power supplies put forward active PFC control chips aiming at the single-phase 85 Vac-270 Vac power grid voltage input range, and the existing chips can be applied to the field of inverter welding and cutting power supplies in the input voltage range, but cannot work in a larger voltage range, and the adaptation range of the input power grid voltage needs to be improved.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a PFC control circuit to realize that drive control circuit has the adaptation scope of great input grid voltage, can make PFC control circuit work at bigger voltage range.

In a first aspect, an embodiment of the present invention provides a PFC control circuit, including:

the driving control circuit comprises a voltage detection end and a driving signal output end, and is used for adjusting a signal output by the driving signal output end according to a signal of the voltage detection end;

the segmented voltage circuit comprises an input end, an output end and a control end, wherein the output end of the segmented voltage circuit is electrically connected with the voltage detection end of the drive control circuit, and the segmented voltage circuit is used for dividing the voltage input by the input end into at least two grades of voltages according to the signal of the control end and outputting the voltages from the output end;

the starting control circuit comprises an input end and an output end, the output end of the starting control circuit is electrically connected with the control end of the segmented voltage circuit, and the starting control circuit is used for controlling the grade of the voltage output by the segmented voltage circuit according to the control signal input by the input end.

Optionally, the driving control circuit includes a first resistor, a second resistor, a first capacitor, a second capacitor, and a PFC control chip; the first end of the first resistor is an input end of the driving control circuit, the second end of the first resistor is electrically connected with a current sampling input pin of the PFC control chip, the first end of the first capacitor is electrically connected with the second end of the first resistor, the second end of the first capacitor is grounded, the first end of the second capacitor is electrically connected with a feedback constant correction input pin of the PFC control chip, the second end of the second capacitor is electrically connected with the second end of the first capacitor, the first end of the second resistor is electrically connected with a frequency setting input pin of the PFC control chip, the second end of the second resistor is electrically connected with the second end of the second capacitor, the driving control pin of the PFC control chip is used as a driving signal output end of the driving control circuit, and the voltage feedback correction pin of the PFC control chip is used as a voltage detection end of the driving control circuit and is electrically connected with the segment voltage circuit.

Optionally, the segmented voltage circuit includes a third resistor, a fourth resistor, a fifth resistor, and an isolation circuit; the first end of the third resistor is used as the input end of the segmented voltage circuit, the first end of the fourth resistor is electrically connected with the first end of the third resistor, the second end of the fourth resistor is electrically connected with the first end of the isolation circuit, the second end of the isolation circuit is electrically connected with the second end of the third resistor, the first end of the fifth resistor is electrically connected with the second end of the third resistor, the second end of the fifth resistor is grounded, the first end of the isolation circuit is used as the control end of the segmented voltage circuit and is electrically connected with the starting control circuit, and the second end of the third resistor is used as the output end of the segmented voltage circuit and is electrically connected with the driving control circuit.

Optionally, the start control circuit includes a sixth resistor, a seventh resistor, a third capacitor, a first switching tube and a second switching tube; the first end of the sixth resistor is an input end of the starting control circuit, the second end of the sixth resistor is electrically connected with the first end of the first switch tube, the second end of the first switch tube is electrically connected with the power supply, the control end of the first switch tube is electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is electrically connected with the first end of the second switch tube, the first end of the third capacitor is electrically connected with the first end of the second switch tube, the second end of the third capacitor is electrically connected with the second end of the second switch tube, the second end of the second switch tube is grounded, and the control end of the second switch tube is electrically connected with the segment voltage circuit as an output end of the starting control circuit.

Optionally, the driving control circuit further includes an eighth resistor, a fourth capacitor, and a fifth capacitor, where a first end of the eighth resistor is electrically connected to the voltage constant correction pin of the PFC control chip, a second end of the eighth resistor is electrically connected to a first end of the fourth capacitor, a second end of the fourth capacitor is electrically connected to a second end of the fifth resistor, a first end of the fifth capacitor is electrically connected to a first end of the eighth resistor, and a second end of the fifth capacitor is electrically connected to a second end of the fourth capacitor.

Optionally, the isolation circuit is a diode, the first end of the isolation circuit is a positive end of the diode, and the second end of the isolation circuit is a negative end of the diode.

Optionally, the segmented voltage circuit further includes a sixth capacitor, a first end of the sixth capacitor is electrically connected to the second end of the isolation circuit, and a second end of the sixth capacitor is electrically connected to the second end of the fifth resistor.

Optionally, the first switch tube and the second switch tube are both triodes, the first end of the first switch tube is a base, the second end of the first switch tube is an emitter, the control end of the first switch tube is a collector, the first end of the second switch tube is a base, the second end of the second switch tube is an emitter, and the control end of the second switch tube is a collector.

Optionally, the start control circuit further includes a ninth resistor, a tenth resistor and a zener diode, a first end of the ninth resistor is electrically connected to the first end of the first switch tube, a second end of the ninth resistor is electrically connected to the second end of the first switch tube, a first end of the tenth resistor is electrically connected to the first end of the third capacitor, a second end of the tenth resistor is electrically connected to the second end of the third capacitor, the first end of the third capacitor is electrically connected to the second switch tube through the zener diode, a negative end of the zener diode is electrically connected to the first end of the third capacitor, and a positive end of the zener diode is electrically connected to the first end of the second switch tube.

Optionally, the control end of the first switching tube is further electrically connected to a power pin of the PFC control chip.

The embodiment of the utility model provides a PFC control circuit, including drive control circuit, segmentation voltage circuit and start control circuit, drive control circuit detects the signal adjustment drive signal output's signal of end according to the voltage, start control circuit's output and segmentation voltage circuit's control end electric connection, start control circuit controls the grade of the voltage of segmentation voltage circuit output according to the control signal input of input, segmentation voltage circuit's output and drive control circuit's voltage detection end electric connection, segmentation voltage circuit is according to the signal of control end, divide the voltage of input into the voltage of at least two grades and export drive control circuit from the output, therefore, the voltage input range of the drive control circuit is expanded, the drive control circuit has a larger adaptation range of the input power grid voltage, and the PFC control circuit can work in a larger voltage range.

Drawings

Fig. 1 is a block diagram of a PFC control circuit according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a driving control circuit according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a segmented voltage circuit according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a start control circuit according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a PFC control circuit according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

This embodiment provides a PFC control circuit, this embodiment can be applicable to the fields such as inverter type welding and cutting power that adopt PFC control circuit, and fig. 1 is the utility model provides a PFC control circuit's block diagram, refer to fig. 1, this PFC control circuit includes: a drive control circuit 10, a segment voltage circuit 20, and a start control circuit 30;

the driving control circuit 10 includes a voltage detecting terminal a1 and a driving signal output terminal B1, and the driving control circuit 10 is configured to adjust a signal output by the driving signal output terminal B1 according to a signal of the voltage detecting terminal a 1;

the segmented voltage circuit 20 comprises an input end C1, an output end a2 and a control end D1, the output end a2 of the segmented voltage circuit is electrically connected with a voltage detection end a1 of the drive control circuit, and the segmented voltage circuit is used for dividing the voltage input by the input end C1 into at least two grades of voltages according to the signal of the control end D1 and outputting the voltages from the output end a 2;

the start-up control circuit 30 includes an input terminal E1 and an output terminal D2, the output terminal D2 of the start-up control circuit 30 is electrically connected to the control terminal D1 of the segment voltage circuit 20, and the start-up control circuit 30 is configured to control the level of the voltage output by the segment voltage circuit 20 according to the control signal input from the input terminal E1.

In the inverter type welding and cutting apparatus, for example, the ac power input from the power grid is converted into dc power by the inverter power supply to power the inverter type welding and cutting apparatus, the control circuit of the inverter power supply may adopt the PFC control circuit of this embodiment, the input terminal E1 of the start control circuit 30 may input a start control signal, the start control signal may be a high-level or low-level start control signal, the start control circuit 30 controls the signal input to the control terminal D1 of the segmented voltage circuit 20 according to the start control signal, so that the segmented voltage circuit 20 divides the voltage input at the input terminal C1 into at least two levels of voltage according to the signal of the control terminal D1, and outputs the voltage from the output terminal a2 to the drive control circuit 10, for example, the segmented voltage output by the segmented voltage output circuit V1 in the starting process, and after the start is completed, the segmented voltage output circuit V2 is controlled, the voltage V1 and the voltage V2 are not equal, that is, the segment voltage circuit 20 is controlled to output two levels of voltages V1 and V2. The start control circuit 30 can control the segment voltage circuit 20 to output at least two levels of voltages, and increase the voltage range output by the segment voltage circuit 20, so as to increase the voltage range input to the drive control circuit 10 through the voltage detection terminal a 1. For example, in the inverter type welding and cutting device, when the voltage of the inverter power supply input to the inverter type welding and cutting device is lower than 85Vac, the protection threshold of the drive control circuit 10 is locked and cannot be started normally, when the voltage input to the inverter power supply is higher than 270Vac, the start current surge of the drive control circuit 10 greatly affects the normal operation of the inverter power supply, in the PFC control circuit of the present embodiment, when the voltage input to the inverter power supply is lower than 85Vac, the protection threshold of the drive control circuit 10 is locked and is not started, when the voltage input to the inverter power supply is higher than 270Vac, and the voltage is between 270Vac and 660Vac, the output voltage of the main circuit of the inverter power supply is input to the segment voltage circuit 20, and the input of the low-level start control signal by the start control circuit can reduce the voltage output to the drive control circuit 10 by the segment voltage circuit 20 at the initial stage of start, so as to achieve the purpose of reducing the normal start surge current, therefore, the input voltage of the inverter power supply can be between 270Vac and 660Vac, the operable input range of the alternating current voltage of the inverter power supply is increased from 85Vac to 265Vac to 85Vac to 660Vac, the input of the inverter power supply can be matched with the single-phase and three-phase power grid voltage from 110Vac to 575Vac, and the matching range of the inverter power supply in the inverter type welding and cutting equipment to the power grid voltage can be increased.

The PFC control circuit provided in this embodiment comprises a driving control circuit, a segment voltage circuit, and a start control circuit, wherein the driving control circuit adjusts a signal output by a driving signal output end according to a signal of a voltage detection end, an output end of the start control circuit is electrically connected to a control end of the segment voltage circuit, the start control circuit controls a level of a voltage output by the segment voltage circuit according to a control signal input by an input end, the output end of the segment voltage circuit is electrically connected to the voltage detection end of the driving control circuit, the segment voltage circuit divides the voltage input by the input end into at least two levels of voltages according to the signal of the control end and outputs the at least two levels of voltages from the output end to the driving control circuit, therefore, the voltage input range of the drive control circuit is expanded, the drive control circuit has a larger adaptation range of the input power grid voltage, and the PFC control circuit can work in a larger voltage range.

Fig. 2 is a schematic structural diagram of a driving control circuit according to an embodiment of the present invention, and on the basis of the foregoing technical solution, optionally, referring to fig. 2, the driving control circuit 10 includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, and a PFC control chip 11; a first end of the first resistor R1 is an input terminal F1 of the driving control circuit 10, a second end of the first resistor R1 is electrically connected to the current sampling input pin 3 of the PFC control chip 11, a first end of the first capacitor C1 is electrically connected to a second end of the first resistor R1, a second end of the first capacitor C1 is grounded, a first end of the second capacitor C2 is electrically connected to the feedback constant correction input pin 2 of the PFC control chip 11, a second end of the second capacitor C2 is electrically connected to a second end of the first capacitor C1, a first end of the second resistor R2 is electrically connected to the frequency setting input pin 4 of the PFC control chip 11, a second end of the second resistor R2 is electrically connected to a second end of the second capacitor C2, the driving control pin 8 of the PFC control chip 11 serves as a driving signal output terminal B1 of the driving control circuit 10, and the voltage feedback correction pin 6 of the PFC control chip 11 serves as a voltage detection terminal a1 of the driving control circuit 10 and is electrically connected to the segment voltage detection circuit 20.

Illustratively, the model of the PFC control chip 11 may be ICE2PCS01G, the PFC control chip 11 may be an active PFC control chip, the power supply pin 7 of the PFC control chip 11 inputs power, the input terminal F1 of the driving control circuit 10 may input a current sampling signal of the inverter main circuit electrically connected to the PFC control circuit, and the current sampling signal is input to the current sampling input pin 3 of the PFC control chip 11 through the first resistor R1.

Fig. 3 is a schematic structural diagram of a segmented voltage circuit according to an embodiment of the present invention, and optionally, referring to fig. 3, the segmented voltage circuit 20 includes a third resistor R4, a fourth resistor R5, a fifth resistor R6, and an isolation circuit 21; a first end of the third resistor R4 is used as an input end C1 of the segment voltage circuit 20, a first end of the fourth resistor R5 is electrically connected to a first end of the third resistor R4, a second end of the fourth resistor R5 is electrically connected to a first end of the isolation circuit 21, a second end of the isolation circuit 21 is electrically connected to a second end of the third resistor R4, a first end of the fifth resistor R6 is electrically connected to a second end of the third resistor R4, a second end of the fifth resistor R6 is grounded, a first end of the isolation circuit 21 is electrically connected to the start-up control circuit as a control end D1 of the segment voltage circuit 20, and a second end of the third resistor R4 is electrically connected to the drive control circuit as an output end of the segment voltage circuit 20.

Specifically, the connection relationship between the fourth resistor R5 and the third resistor R4 and the connection relationship between the fourth resistor R5 and the fifth resistor R6 are affected by the on/off of the isolation circuit 21, the segmented voltage circuit 20 inputs voltage through the input end C1, when the isolation circuit 21 is turned on, the third resistor R4 and the fourth resistor R5 are connected in parallel and then connected in series with the fifth resistor R6, and the fourth resistor R5 provides superposed current to enable the segmented voltage circuit 20 to output a first-level voltage when the isolation circuit 21 is turned on; when the isolation circuit 21 is turned off, the isolation circuit 21 can isolate the influence of the fourth resistor R5 on the voltage division loop of the third resistor R4 and the fifth resistor R6, and the segmented voltage circuit 20 outputs a second level voltage different from the first level voltage range, so that the segmented voltage circuit 20 outputs two levels of voltage, and the output voltage range is larger.

Alternatively, referring to fig. 3, the isolation circuit 21 is a diode D1, the first terminal of the isolation circuit 21 is the positive terminal of a diode D1, and the second terminal of the isolation circuit 21 is the negative terminal of a diode D1.

Specifically, according to the characteristic that the diode is turned on in the forward direction and turned off in the reverse direction, when the second switching tube is turned off, the positive terminal of the diode D1 electrically connected to the control terminal of the second switching tube is at a high level, and the diode D1 is turned on; when the second switch tube is turned on, the positive terminal of the diode D1 electrically connected to the control terminal of the second switch tube is at a low level, the diode D1 is turned off, and the influence of the fourth resistor R5 on the voltage division loop of the third resistor R4 and the fifth resistor R6 is isolated.

Optionally, referring to fig. 3, the segmented voltage circuit 20 further includes a sixth capacitor C5, a first terminal of the sixth capacitor C5 is electrically connected to the second terminal of the isolation circuit 21, and a second terminal of the sixth capacitor C5 is electrically connected to the second terminal of the fifth resistor R6.

The sixth capacitor C5 is connected in parallel with the fifth resistor R6 and then grounded, the segmented voltage circuit 20 divides the voltage input by the input terminal C1 into at least two levels of voltages according to the signal of the control terminal D1 and outputs the voltages from the output terminal a2 to the driving control circuit 10, and the PFC control chip can be adapted to single-phase and three-phase power networks of the alternating current 110Vac to 575 Vac. At present, many manufacturers in the field of power supplies provide active PFC control chips for a single-phase 85 Vac-270 Vac power grid input range, when the voltage input to an inverter power supply in an inverter control circuit of an inverter welding and cutting device is lower than 85Vac, the internal protection threshold of the PFC control chip is locked and cannot be started normally, when the voltage input to the inverter power supply is higher than 270Vac, the starting current impact of the PFC control chip is large, and the normal work of the inverter power supply is greatly influenced by the output voltage plus the BUS value, in the PFC control circuit of the embodiment, when the voltage input to the inverter power supply is lower than 85Vac, the internal protection threshold of the PFC control chip is locked and cannot be started, when the voltage input to the inverter power supply is higher than 270Vac, and when the voltage is between 270Vac and 660Vac, the output voltage of a main circuit of the inverter power supply is input to a segment voltage circuit 20 through an input end C1, and when the starting control circuit inputs a low-level starting control signal, the second switch tube is in a cut-off state, the fourth resistor R5 provides superposed current to reduce the voltage output by the segmented voltage circuit 20 at the initial stage of starting to the PFC control chip, so as to achieve the purpose of reducing the starting impact current for normal starting, thereby ensuring that the input voltage of the inverter power supply can be between 270Vac and 660Vac, the working input range of the alternating current voltage of the inverter power supply is increased from 85 Vac-265 Vac to 85 Vac-660 Vac, and the input of the inverter power supply can be matched with the single-phase and three-phase power grid voltage of alternating current 110 Vac-575 Vac.

Fig. 4 is a schematic structural diagram of a start control circuit according to an embodiment of the present invention, and on the basis of the foregoing technical solution, optionally, referring to fig. 4, the start control circuit includes a sixth resistor R7, a seventh resistor R8, a third capacitor C6, a first switch tube Q1, and a second switch tube Q2; a first end of the sixth resistor R7 is an input end E1 of the start control circuit 30, a second end of the sixth resistor R7 is electrically connected to a first end of the first switch tube Q1, a second end of the first switch tube Q1 is electrically connected to + VCC, a control end of the first switch tube Q1 is electrically connected to a first end of the seventh resistor R9, a second end of the seventh resistor R9 is electrically connected to a first end of the second switch tube Q2, a first end of the third capacitor C6 is electrically connected to a first end of the second switch tube Q2, a second end of the third capacitor C6 is electrically connected to a second end of the second switch tube Q2, a second end of the second switch tube Q2 is grounded, and a control end of the second switch tube Q2 is electrically connected to the segment voltage circuit as an output end D2 of the start control circuit 30.

Illustratively, the first switch tube Q1 is turned on at a low level, the second switch tube Q2 is turned on at a high level, the input end E1 of the start control circuit 30 can input a start control signal at a low level, the first switch tube Q1 is turned on after the start control signal at the low level is input through the input end E1, the power supply + VCC can charge the third capacitor C6 through the seventh resistor R9, during the charging process of the third capacitor C6, the first end of the second switch tube Q2 is at the low level, the second switch tube Q2 is turned off, that is, the first end of the isolation circuit in the segment voltage circuit electrically connected with the control end of the second switch tube Q2 is at the high level, when the isolation circuit is turned on, the fourth resistor provides a superimposed current to make the segment voltage circuit output a first level of voltage when the isolation circuit is turned on; after the third capacitor C6 is fully charged, the voltage of the power supply + VCC is input to the first end of the second switch tube Q2 through the seventh resistor R9, at this time, the first end of the second switch tube Q2 is at a high level, the second switch tube Q2 is turned on, the second end of the second switch tube Q2 is grounded, the first end of the isolation circuit electrically connected to the control end of the second switch tube Q2 is at a low level, the isolation circuit is turned off at this time, the isolation circuit isolates the influence of the fourth resistor on the third resistor and the fifth resistor voltage division loop, the segment voltage circuit outputs a second-level voltage different from the first-level voltage range, and the control circuit is started to control the level of the voltage output by the segment voltage circuit.

Optionally, referring to fig. 2 and fig. 3, the driving control circuit 10 further includes an eighth resistor R3, a fourth capacitor C3, and a fifth capacitor C4, a first end of the eighth resistor R3 is electrically connected to the voltage constant correction pin 5 of the PFC control chip 11, a second end of the eighth resistor R3 is electrically connected to a first end of the fourth capacitor C3, a second end of the fourth capacitor C3 is electrically connected to a second end of the fifth resistor R6, a first end of the fifth capacitor C4 is electrically connected to a first end of the eighth resistor R3, and a second end of the fifth capacitor C4 is electrically connected to a second end of the fourth capacitor C3.

The second end of the fourth capacitor C3 in the driving control circuit 10 is electrically connected to the second end of the fifth resistor R6 in the segment voltage circuit 20 and then grounded, and the voltage constant correction pin 5 of the PFC control chip 11 is grounded through the eighth resistor R3, the fourth capacitor C3 and the fifth capacitor C4.

Optionally, referring to fig. 4, the first switch tube Q1 and the second switch tube Q2 are both triodes, the first end of the first switch tube Q1 is a base, the second end of the first switch tube Q1 is an emitter, the control end of the first switch tube Q1 is a collector, the first end of the second switch tube Q2 is a base, the second end of the second switch tube Q2 is an emitter, and the control end of the second switch tube Q2 is a collector.

Illustratively, the first switch tube Q1 is a PNP type triode, the first switch tube Q1 is turned on when the input end E1 of the start control circuit 30 inputs a low-level start control signal, the second switch tube Q2 is an NPN type triode, the power supply + VCC charges the third capacitor C6 through the first switch tube Q1 and the seventh resistor R9 after the first switch tube Q1 is turned on, the base of the second switch tube Q2 is at a high level after the third capacitor C6 is fully charged, the second switch tube Q2 is turned on, that is, the delayed second switch tube Q2 is turned on after a certain time (the charging time of the third capacitor C6 is up to the time when the second switch tube Q2 is turned on), and the start control circuit 10 controls the level of the voltage output by the segmented voltage circuit 10 through the off and on switch states of the second switch tube Q2.

Optionally, referring to fig. 4, the start-up control circuit 30 further includes a ninth resistor R8, a tenth resistor R10, and a zener diode Z1, wherein a first end of the ninth resistor R8 is electrically connected to a first end of the first switch Q1, a second end of the ninth resistor R8 is electrically connected to a second end of the first switch Q1, a first end of the tenth resistor R10 is electrically connected to a first end of the third capacitor C6, a second end of the tenth resistor R10 is electrically connected to a second end of the third capacitor C6, a first end of the third capacitor C6 is electrically connected to the second switch Q2 through the zener diode Z1, a negative end of the zener diode is electrically connected to a first end of the third capacitor C6, and a positive end of the zener diode Z1 is electrically connected to a first end of the second switch Q2.

Specifically, the tenth resistor R10 is connected in parallel with the third capacitor C6 and then grounded, after the power supply is full of the third capacitor C6, the power supply voltage is input to the negative terminal of the zener diode Z1 through the seventh resistor R9, the zener diode Z1 is in reverse breakdown, and the zener diode Z1 plays a role in voltage stabilization after being in reverse breakdown, the first terminal of the second switching tube Q2 electrically connected with the positive terminal of the zener diode Z1 is at a high level, and the second switching tube Q2 is in high level conduction; during the charging process of the third capacitor C6, the voltage at the negative terminal of the zener diode Z1 is low, Z1 is turned off in the reverse direction, that is, the first terminal of the second switching tube Q2 electrically connected to the positive terminal of the zener diode Z1 is at a low level, and the second switching tube Q2 is turned off at a low level, so that the switching state of the start-up control circuit 10, in which the second switching tube Q2 is turned off and on, controls the level of the voltage output by the segment voltage circuit 10.

Fig. 5 is a schematic structural diagram of a PFC control circuit according to an embodiment of the present invention, wherein a connection relationship between the driving control circuit 10, the segment voltage circuit 20 and the start control circuit 30 is as shown in fig. 5, a control terminal of the first switch tube Q1 is electrically connected to a power pin 7 of the PFC control chip 11, when a low-level start control signal is input from an input terminal E1 of the start control circuit 30, the first switch tube Q1 is turned on, a path between the power supply + VCC and the power pin 7 of the PFC control chip 11 is turned on, the power supply supplies power to the PFC control chip 11, and the power supply charges the third capacitor C6 through the first switch tube Q1 and the seventh resistor R9, during a charging process of the third capacitor C6, a first end of the second switch tube Q2 is at a low level, the second switch tube Q2 is turned off, that is a first end of a diode D1 in the segment voltage circuit 20 electrically connected to the control terminal of the second switch tube Q2 is at a high level, when the diode D1 is turned on, the fourth resistor R5 provides the superimposed current to turn on the diode D1, and the segment voltage circuit 20 outputs the first-level voltage, which is output to the voltage feedback correction pin 6 of the PFC control chip 11 through the second end of the third resistor R4; after the third capacitor C6 is fully charged, the first terminal of the second switch Q2 is at a high level, the second switch Q2 is turned on, that is, the second switch Q2 is turned on after a certain time (from the charging time of the third capacitor C6 to the time when the second switch Q2 is turned on) elapses, the second terminal of the second switch Q2 is grounded, the first terminal of the diode D1 electrically connected to the control terminal of the second switch Q2 is at a low level, at this time, the diode D1 is turned off, the diode D1 isolates the influence of the fourth resistor R5 on the voltage dividing loop of the third resistor R4 and the fifth resistor R6, the segment voltage circuit 20 outputs a second-level voltage different from the first-level voltage range, and the start control circuit 30 controls the segment voltage circuit 20 to output the level of the voltage to the drive control circuit 10.

For example, in the control circuit of the inverter power supply of the inverter type welding and cutting equipment, when the voltage input to the inverter power supply is lower than 85Vac, the internal protection threshold of the PFC control chip is locked and cannot be normally started, when the voltage input to the inverter power supply is higher than 270Vac, the start current impact of the PFC control chip is large, and the output voltage + BUS value greatly affects the normal work of the inverter power supply, in the PFC control circuit of the present embodiment, when the voltage input to the inverter power supply is lower than 85Vac, the internal protection threshold of the PFC control chip is locked and cannot be started, when the voltage input to the inverter power supply is higher than 270Vac, and the voltage is between 270Vac and 660Vac, the output voltage of the main circuit of the inverter power supply is input to the segment voltage circuit 20 through the input terminal C1, when the start control circuit inputs a low-level start control signal, the second switching tube is in a cut-off state, the fourth resistor R5 provides superposed current in an initial stage, so that the voltage output from the segment voltage circuit 20 which is started, the purpose of reducing normal starting of starting impact current is achieved, so that the input voltage of the inverter power supply can be between 270Vac and 660Vac, the working input range of the alternating current voltage of the inverter power supply is increased from 85 Vac-265 Vac to 85 Vac-660 Vac, and the input of the inverter power supply can be adapted to the single-phase and three-phase power grid voltage of alternating current 110Vac to 575 Vac.

The PFC control circuit provided in this embodiment includes a driving control circuit, a segment voltage circuit, and a start control circuit, where the driving control circuit adjusts a signal output by a driving signal output end according to a signal of a voltage detection end, the start control circuit controls a level of a voltage output by the segment voltage circuit according to a control signal input by an input end, and the segment voltage circuit divides the voltage input by the input end into at least two levels according to the signal of the control end and outputs the two levels of voltage from the output end to the driving control circuit, so as to expand a voltage input range of the driving control circuit, achieve a large adaptation range of the driving control circuit to an input grid voltage, and enable the PFC control circuit to operate in a larger voltage range.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A PFC control circuit comprising:

the starting control circuit comprises an input end and an output end, the output end of the starting control circuit is electrically connected with the control end of the segmented voltage circuit, and the starting control circuit is used for controlling the grade of the voltage output by the segmented voltage circuit according to a control signal input by the input end.

2. The PFC control circuit of claim 1, wherein the drive control circuit comprises a first resistor, a second resistor, a first capacitor, a second capacitor and a PFC control chip; the first end of the first resistor is the input end of the drive control circuit, the second end of the first resistor is electrically connected with the current sampling input pin of the PFC control chip, the first end of the first capacitor is electrically connected with the second end of the first resistor, the second end of the first capacitor is grounded, the first end of the second capacitor is electrically connected with a feedback constant correction input pin of the PFC control chip, the second end of the second capacitor is electrically connected with the second end of the first capacitor, the first end of the second resistor is electrically connected with a frequency setting input pin of the PFC control chip, the second end of the second resistor is electrically connected with the second end of the second capacitor, a drive control pin of the PFC control chip is used as a drive signal output end of the drive control circuit, and a voltage feedback correction pin of the PFC control chip is used as a voltage detection end of the driving control circuit and is electrically connected with the segmented voltage circuit.

3. The PFC control circuit of claim 2, wherein the segmented voltage circuit comprises a third resistor, a fourth resistor, a fifth resistor, and an isolation circuit; the first end of the third resistor is used as the input end of the segmented voltage circuit, the first end of the fourth resistor is electrically connected with the first end of the third resistor, the second end of the fourth resistor is electrically connected with the first end of the isolation circuit, the second end of the isolation circuit is electrically connected with the second end of the third resistor, the first end of the fifth resistor is electrically connected with the second end of the third resistor, the second end of the fifth resistor is grounded, the first end of the isolation circuit is used as the control end of the segmented voltage circuit and is electrically connected with the start control circuit, and the second end of the third resistor is used as the output end of the segmented voltage circuit and is electrically connected with the drive control circuit.

4. The PFC control circuit of claim 3, wherein the start-up control circuit comprises a sixth resistor, a seventh resistor, a third capacitor, a first switching tube and a second switching tube; the first end of the sixth resistor is the input end of the start control circuit, the second end of the sixth resistor is electrically connected with the first end of the first switch tube, the second end of the first switch tube is electrically connected with the power supply, the control end of the first switch tube is electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is electrically connected with the first end of the second switch tube, the first end of the third capacitor is electrically connected with the first end of the second switch tube, the second end of the third capacitor is electrically connected with the second end of the second switch tube, the second end of the second switch tube is grounded, and the control end of the second switch tube is used as the output end of the start control circuit and is electrically connected with the segment voltage circuit.

5. The PFC control circuit of claim 3, wherein the driving control circuit further comprises an eighth resistor, a fourth capacitor and a fifth capacitor, wherein a first terminal of the eighth resistor is electrically connected to a voltage constant correction pin of the PFC control chip, a second terminal of the eighth resistor is electrically connected to a first terminal of the fourth capacitor, a second terminal of the fourth capacitor is electrically connected to a second terminal of the fifth resistor, a first terminal of the fifth capacitor is electrically connected to a first terminal of the eighth resistor, and a second terminal of the fifth capacitor is electrically connected to a second terminal of the fourth capacitor.

6. The PFC control circuit of claim 3, wherein the isolation circuit is a diode, the first end of the isolation circuit is a positive terminal of the diode, and the second end of the isolation circuit is a negative terminal of the diode.

7. The PFC control circuit of claim 3, wherein the segmented voltage circuit further comprises a sixth capacitor, a first terminal of the sixth capacitor being electrically connected to the second terminal of the isolation circuit, and a second terminal of the sixth capacitor being electrically connected to the second terminal of the fifth resistor.

8. The PFC control circuit of claim 4, wherein the first switch tube and the second switch tube are both transistors, the first end of the first switch tube is a base, the second end of the first switch tube is an emitter, the control end of the first switch tube is a collector, the first end of the second switch tube is a base, the second end of the second switch tube is an emitter, and the control end of the second switch tube is a collector.

9. The PFC control circuit according to claim 4, wherein the start-up control circuit further comprises a ninth resistor, a tenth resistor and a zener diode, wherein a first end of the ninth resistor is electrically connected to the first end of the first switch tube, a second end of the ninth resistor is electrically connected to the second end of the first switch tube, a first end of the tenth resistor is electrically connected to the first end of the third capacitor, a second end of the tenth resistor is electrically connected to the second end of the third capacitor, a first end of the third capacitor is electrically connected to the second switch tube through the zener diode, a negative end of the zener diode is electrically connected to the first end of the third capacitor, and a positive end of the zener diode is electrically connected to the first end of the second switch tube.

10. The PFC control circuit of claim 4, wherein the control terminal of the first switching tube is further electrically connected to a power pin of the PFC control chip.