PFC circuit and charger

Abstract

The present embodiment provides a PFC circuit and a charger, wherein the PFC circuit includes at least one PFC branch, wherein the PFC branch includes: a zero-crossing detection unit, adapted to store a supply voltage and generate a zero-crossing detection signal when a switch tube in a PFC chip is turned on; and to release the stored electric energy when the switch tube in the PFC chip is turned off; a voltage sampling unit, adapted to collect the supply voltage; a voltage feedback unit, adapted to collect the output voltage on the output circuit when the switch unit is turned on; the PFC chip, adapted to turn on the switch tube when it is determined that the current value corresponding to the zero-crossing detection signal is less than a set current value, so that the switch unit is in an off state; when it is determined that the current value corresponding to the zero-crossing detection signal is greater than the set current value, turn off the switch tube and turn on the switch unit; and adjust the set current value according to the sampling voltage and the feedback voltage to change the on-time of the switch tube. The above technical solution can broaden the output range of the PFC circuit and improve the stability of the output voltage.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of circuit technology, and more particularly to a PFC circuit and a charger. Background Art

[0002] With the development of electronic power technology, in order to reduce the pollution of harmonics to the power grid, power electronic products are required to have PFC circuits to improve the power factor of the output voltage and reduce resonance interference.

[0003] When the PFC circuit is applied to a charger, different devices to be charged require different charging powers. In this context, how to provide a technical solution to broaden the output range of the PFC circuit and improve the stability of the output voltage has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0004] In view of this, the embodiments of the present specification provide a PFC circuit and a charger, which can broaden the output range of the PFC circuit and improve the stability of the output voltage.

[0005] An embodiment of the present specification provides a PFC circuit, comprising at least one PFC branch coupled between an input circuit and an output circuit, wherein the PFC branch comprises: a zero-crossing detection unit, a voltage sampling unit, a PFC chip, a voltage feedback unit, and a switch unit, wherein:

[0006] The zero-crossing detection unit is coupled to the PFC chip and the gating unit respectively, and is adapted to store the supply voltage provided by the input circuit and generate a zero-crossing detection signal to output to the PFC chip when the switch tube in the PFC chip is turned on; and is adapted to release the stored electric energy through the output circuit and charge the output circuit when the switch tube in the PFC chip is turned off;

[0007] The voltage sampling unit is coupled to the PFC chip, and is suitable for collecting the power supply voltage provided by the input circuit, and outputting the sampled voltage to the PFC chip;

[0008] The voltage feedback unit is respectively coupled to the PFC chip, the output circuit and the switch unit, and is adapted to collect the output voltage on the output circuit and output a feedback voltage to the PFC chip when the switch unit is turned on;

[0009] The PFC chip is adapted to, when it is determined that the current value corresponding to the zero-crossing detection signal is less than a set current value, turn on the switch tube in the PFC chip so that the switch unit is in an off state; and, when it is determined that the current value corresponding to the zero-crossing detection signal is greater than the set current value, turn off the switch tube in the PFC chip and turn on the switch unit to connect the zero-crossing detection unit with the output circuit; and, according to the sampling voltage and the feedback voltage, adjust the set current value to change the on-time of the switch tube in the PFC chip.

[0010] Optionally, the zero-crossing detection unit includes a common-mode inductor and a first resistor, wherein:

[0011] The first end of the common mode inductor is connected to the input circuit, the second end thereof is grounded, the third end thereof is respectively connected to the switch unit and the switch tube in the PFC chip, and the fourth end thereof is connected to the first end of the first resistor;

[0012] The second end of the first resistor is connected to the PFC chip.

[0013] Optionally, the voltage sampling unit includes: a first sampling module and a second sampling module, wherein: a first end of the first sampling module is connected to the input circuit, and a second end thereof is respectively connected to a first end of the second sampling module and the PFC chip; a second end of the second sampling module is connected to the PFC chip;

[0014] The first sampling module includes a first sampling resistor, a second sampling resistor and a third sampling resistor, the first end of the first sampling resistor serves as the first end of the first sampling module, and the second end of the first sampling resistor is connected to the first end of the second sampling resistor; the second end of the second sampling resistor is connected to the first end of the third sampling resistor; the second end of the third sampling resistor serves as the second end of the first sampling module;

[0015] The second sampling module includes a fourth sampling resistor and a sampling capacitor, wherein a first end of the fourth sampling resistor serves as a first end of the second sampling module and is connected to a first end of the sampling capacitor, and a second end of the fourth sampling resistor serves as a second end of the second sampling module and is connected to a second end of the sampling capacitor.

[0016] Optionally, the voltage feedback unit includes: a first feedback module and a second feedback module, wherein: a first end of the first feedback module is respectively connected to the output circuit and the switch unit, and a second end thereof is respectively connected to a first end of the second feedback module and the PFC chip; a second end of the second feedback module is connected to the PFC chip;

[0017] The first feedback module includes: a first feedback resistor, a second feedback resistor and a third feedback resistor, wherein the first end of the first feedback resistor serves as the first end of the first feedback module, and the second end of the first feedback resistor is connected to the first end of the second feedback resistor; the second end of the second feedback resistor is connected to the first end of the third feedback resistor; and the second end of the third feedback resistor serves as the second end of the first feedback module;

[0018] The second feedback module includes: a fourth feedback resistor, a fifth feedback resistor and a feedback capacitor, the first end of the fourth feedback resistor serves as the first end of the second feedback module and is connected to the first end of the feedback capacitor, the second end of the fourth feedback resistor is connected to the first end of the fifth feedback resistor, and the second end of the fifth feedback resistor serves as the second end of the second feedback module and is connected to the second end of the feedback capacitor.

[0019] Optionally, the PFC branch further includes:

[0020] A compensation unit is coupled to the PFC chip and the voltage feedback unit respectively, and is suitable for: the compensation unit comprises: a first compensation capacitor, a second compensation capacitor and a first compensation resistor, the first end of the first compensation capacitor is respectively connected to the first end of the first compensation resistor and the PFC chip, and the second end thereof is respectively connected to the second end of the second compensation capacitor and the voltage feedback unit; the second end of the first compensation resistor is connected to the first end of the second compensation capacitor;

[0021] a filtering unit, coupled to the PFC chip, suitable for balancing the low frequency of the input signal and the high frequency of the output signal; the filtering unit comprises a third filtering capacitor, a fourth filtering capacitor and a fifth filtering capacitor, the first end of the third filtering capacitor is respectively connected to the first end of the fourth filtering capacitor and the first end of the fifth filtering capacitor, and connected to the PFC chip; the second end of the third filtering capacitor is respectively connected to the second end of the fourth filtering capacitor and the second end of the fifth filtering capacitor, and connected to the PFC chip; wherein the first end of the third filtering capacitor, the first end of the fourth filtering capacitor and the first end of the fifth filtering capacitor are respectively connected to different ports of the PFC chip.

[0022] Optionally, the PFC circuit further includes: a power supply branch, coupled to the PFC branch, and suitable for providing a driving voltage for the PFC chip, wherein when at least one of the PFC branches is a plurality of PFC branches, the power supply branch provides a driving voltage for the plurality of PFC chips, and the plurality of PFC chips are coupled to each other and work in time sharing.

[0023] The embodiment of this specification also provides a charger, including:

[0024] The PFC circuit as described in any of the above embodiments is suitable for converting the supply voltage provided by the input circuit into an output voltage;

[0025] The voltage conversion circuit is coupled to the PFC circuit and is suitable for converting the type and amplitude of the output voltage output by the PFC circuit and outputting a target voltage.

[0026] Optionally, the voltage conversion circuit includes a plurality of voltage conversion branches, each of which is coupled to at least one PFC branch in the PFC circuit, wherein the voltage conversion branch includes: a voltage transformation unit, a control chip and a gating unit, wherein:

[0027] The voltage transformation unit is coupled to the PFC circuit and the control chip, and is adapted to convert the type and amplitude of the output voltage to obtain the target voltage when the switch tube in the control chip is in the on state;

[0028] The control chip is coupled to the gating unit and is adapted to convert the target voltage into a current value, and when it is determined that the current value is greater than a preset current, turn off the switch tube in the control chip and output a control signal to the gating unit;

[0029] The gating unit is coupled to the voltage transformation unit and is adapted to gating a path between the voltage transformation unit and the ground according to the control signal to output the target voltage.

[0030] Optionally, the selection unit includes: a first switching device and a second switching device, the first end of the first switching device is connected to the first end of the second switching device and connected to the control chip; the second end of the first switching device is respectively connected to the transformation unit and the second end of the second switching device; the third end of the first switching device is connected to the third end of the second switching device and is grounded.

[0031] Optionally, when the PFC circuit includes a power supply branch, the transformation unit includes a third transformer, and the charger also includes a power supply unit, wherein: a first end of the third transformer is connected to the PFC circuit, and a second end of the third transformer is connected to the power supply unit, and is suitable for converting the target voltage into an operating voltage; and the power supply unit is suitable for connecting the path between the third transformer and the power supply branch to output the operating voltage to the power supply branch.

[0032] With the PFC circuit provided by the embodiment of the present specification, when connected to the input circuit, the voltage sampling unit can collect the supply voltage provided by the input circuit; and when the switch tube in the PFC chip is turned on, the gating unit is in a disconnected state, the zero-crossing detection unit can store the supply voltage provided by the input circuit, and can output the generated zero-crossing detection signal to the PFC chip. In this process, the current value corresponding to the zero-crossing detection signal gradually increases, and when the PFC chip determines that the current value corresponding to the zero-crossing detection signal is greater than the sampling current, it can turn off the switch tube in the PFC chip. At this time, the switch unit is gated, and can connect the zero-crossing detection unit and the output circuit, so that the zero-crossing detection unit can release the stored electric energy through the output circuit, so that the voltage feedback unit can collect the output voltage on the output circuit, and output the feedback voltage to the PFC chip, thereby the PFC chip can adjust the set current value according to the sampling voltage and the feedback voltage, so that the conduction time of the switch tube in the PFC chip can be changed, and the electric energy stored in the zero-crossing detection unit can be adjusted, and the output voltage on the output circuit can be changed, so that the output range of the PFC circuit can be widened and the stability of the output voltage can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of a PFC branch circuit in an embodiment of this specification is shown;

[0035] Figure 2 A schematic diagram of the structure of a zero-crossing detection unit in an embodiment of this specification is shown;

[0036] Figure 3 A schematic diagram of the structure of a voltage sampling unit in an embodiment of this specification is shown;

[0037] Figure 4 A schematic diagram of the structure of a voltage feedback unit in an embodiment of this specification is shown;

[0038] Figure 5 A specific structural diagram of a PFC branch in an embodiment of this specification is shown;

[0039] Figure 6 A schematic diagram of the structure of a charger in an embodiment of this specification is shown;

[0040] Figure 7A schematic diagram of the structure of a voltage conversion branch in an embodiment of this specification is shown. DETAILED DESCRIPTION

[0041] As described in the background art, different devices to be charged require different charging powers, and when the voltage at the input end remains fixed, the PFC circuit generally corresponds to one output value and cannot adapt to different devices to be charged.

[0042] In order to solve the above technical problems, the embodiments of the present specification provide a PFC circuit, which can adjust the set current value according to the sampling voltage and the feedback voltage, so as to adjust the conduction time of the switch tube in the PFC chip, and then adjust the electric energy stored in the zero-crossing detection unit, change the output voltage on the output circuit, thereby widening the output range of the PFC circuit, improving the stability of the output voltage, and outputting different voltage values ​​to the device to be charged, thereby widening the output range of the PFC circuit, and then improving the compatibility of the product.

[0043] In order to enable those skilled in the art to better understand the inventive concept, working principle and advantages of the embodiments of this specification, the PFC circuit in the embodiments of this specification is described in detail below.

[0044] In specific implementations, considering the influence of various factors, the charging power required by the device to be charged may change, so the PFC circuit needs to provide a stable voltage for the device to be charged in various scenarios.

[0045] In some embodiments of the present specification, the set current value can be adjusted according to the sampling voltage and the feedback voltage, thereby adjusting the conduction time of the switch tube in the PFC chip to change the electric energy value stored in the zero-crossing detection unit, so that when the switch tube in the PFC chip is turned off, different electric energy values ​​can be output to the device to be charged.

[0046] Specifically, the PFC circuit in the embodiments of this specification includes at least one PFC branch coupled between the input circuit and the output circuit, and the PFC branch includes: a zero-crossing detection unit, a voltage sampling unit, a PFC chip and a voltage feedback unit.

[0047] When connected to the input circuit, the voltage sampling unit can collect the supply voltage provided by the input circuit; and when the switch tube in the PFC chip is turned on, the gating unit is in a disconnected state, the zero-crossing detection unit can store the supply voltage provided by the input circuit, and can output the generated zero-crossing detection signal to the PFC chip. In this process, the current value corresponding to the zero-crossing detection signal gradually increases. When the PFC chip determines that the current value corresponding to the zero-crossing detection signal is greater than the sampling current, it can turn off the switch tube in the PFC chip. At this time, the switch unit is gated and can connect the zero-crossing detection unit with the output circuit, so that the zero-crossing detection unit can release the stored electric energy through the output circuit, so that the voltage feedback unit can collect the output voltage on the output circuit and output the feedback voltage to the PFC chip, thereby the PFC chip can adjust the set current value according to the sampling voltage and the feedback voltage, so that the conduction time of the switch tube in the PFC chip can be changed, and the electric energy stored in the zero-crossing detection unit can be adjusted, and the output voltage on the output circuit can be changed, so that the output range of the PFC circuit can be widened and the stability of the output voltage can be improved.

[0048] For ease of understanding, the structure and working principle of the PFC circuit in the embodiments of this specification are described in detail below by taking a PFC circuit having a PFC branch coupled between an input circuit and an output circuit as an example.

[0049] See also Figure 1 The structural diagram of a PFC branch in the embodiment of this specification is shown in FIG. Figure 1 As shown, the PFC branch 100 can be coupled to the input circuit ( Figure 1 not shown) and output circuit ( Figure 1 not shown).

[0050] See also Figure 1 , the PFC branch 100 may include: a zero-crossing detection unit 110, a voltage sampling unit 120, a PFC chip 130, a voltage feedback unit 140 and a switch unit 150, wherein:

[0051] The zero-crossing detection unit 110 is coupled to the PFC chip 130 and the switch unit 150, respectively, and is suitable for switching the switch tube ( Figure 1 When the switch tube in the PFC chip 130 is turned off, the stored electric energy is released through the output circuit, and the output circuit is charged;

[0052] The voltage sampling unit 120 is coupled to the PFC chip 130 and is suitable for collecting the supply voltage provided by the input circuit and outputting the sampled voltage to the PFC chip 130;

[0053] The voltage feedback unit 140 is respectively coupled to the PFC chip 130, the output circuit and the switch unit 150, and is adapted to collect the output voltage Vout on the output circuit and output a feedback voltage to the PFC chip 130 when the switch unit 150 is turned on;

[0054] The PFC chip 130 is adapted to turn on the switch tube in the PFC chip 130 when it is determined that the current value corresponding to the zero-crossing detection signal is less than the set current value, so that the switch unit 150 is in an off state; and, when it is determined that the current value corresponding to the zero-crossing detection signal is greater than the set current value, turn off the switch tube in the PFC chip 130 and turn on the switch unit 150 to connect the zero-crossing detection unit 110 and the output circuit; and, according to the sampling voltage and the feedback voltage, adjust the set current value to change the conduction time of the switch tube in the PFC chip 130.

[0055] More specifically, when the PFC chip 130 obtains the feedback voltage, it can compare the feedback voltage with the preset voltage. When it is determined that the feedback voltage is greater than the preset voltage, it means that the output voltage is greater than the set voltage. At this time, the set current value can be reduced. In this way, when the input voltage remains unchanged, the electric energy stored in the zero-crossing detection unit 110 is reduced, and the output voltage can be reduced. Alternatively, when it is determined that the feedback voltage is less than the preset voltage, it means that the output voltage is lower than the set voltage. At this time, the set current value can be increased. In this way, when the input voltage remains unchanged, the electric energy stored in the zero-crossing detection unit 110 is increased, and the output voltage can be increased.

[0056] Combination Figure 1 , explaining the working principle of the PFC branch 100.

[0057] When the switch tube in the PFC chip 130 is turned on, the switch unit 150 is in a disconnected state, and thus the path between the zero-crossing detection unit 110 and the output circuit is disconnected; when the switch tube in the PFC chip is turned on, the first end of the switch unit 150 is grounded, and at this time the switch unit 150 is in a turned-on state, and thus the path between the zero-crossing detection unit 110 and the output circuit is turned on.

[0058] In the initial stage, the switch tube ( Figure 1 The switching unit 150 is in a closed state, the switching unit 150 is in a disconnected state, and the path between the zero-crossing detection unit 110 and the output circuit is disconnected. At this time, the zero-crossing detection unit 110 can store the power supply voltage Vin provided by the input circuit according to the power supply voltage Vin provided by the input circuit, and generate a zero-crossing detection signal.

[0059] At the same time, the voltage sampling unit 120 can collect the power supply voltage Vin provided by the input circuit, and output the sampled voltage to the PFC chip 130 .

[0060] As the electric energy stored in the zero-crossing detection unit gradually increases, the current value corresponding to the zero-crossing detection signal gradually increases. When the PFC chip 130 determines that the current value corresponding to the zero-crossing detection signal is greater than the set current (for example, 0A, or other values), it can turn off the switch tube in the PFC chip 130. At this time, the switch unit 150 is enabled and can connect the path between the zero-crossing detection unit 110 and the output circuit. The zero-crossing detection unit 110 can release the stored electric energy through the output circuit, so that the voltage feedback unit 140 can collect the output voltage on the output circuit and output the feedback voltage to the PFC chip 130.

[0061] During this process, the current value corresponding to the zero-crossing detection signal gradually decreases. When the current value corresponding to the zero-crossing detection signal decreases to the set current value, the switch tube in the PFC chip 130 is turned on, and the zero-crossing detection unit 110 stores the power supply voltage Vin provided by the input circuit again, that is, the cycle of internal charging-external discharging is realized.

[0062] In this process, the PFC chip can adjust the value of the set current according to the sampling voltage and the feedback voltage. In this way, when the supply voltage Vin remains unchanged, the change trend of the current value corresponding to the zero-crossing detection signal remains unchanged. By adjusting the value of the set current, the conduction time of the switch tube in the PFC chip can be adjusted, and then the electric energy stored in the zero-crossing detection unit can be adjusted, and the output voltage on the output circuit can be changed, thereby widening the output range of the PFC circuit and improving the stability of the output voltage.

[0063] In some embodiments of this specification, Figure 1 , see Figure 2 A schematic diagram of the structure of a zero-crossing detection unit in an embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the zero-crossing detection unit 110 may include a common-mode inductor 111 and a first resistor R1, wherein: a first end of the common-mode inductor 111 is connected to the input circuit, a second end thereof is grounded, a third end thereof is respectively connected to the switch tubes in the switch unit 150 and the PFC chip 130, and a fourth end thereof is connected to a first end of the first resistor R1; and a second end of the first resistor R1 is connected to the PFC chip 130.

[0064] Specifically, when the PFC branch 100 is connected to the input circuit, the common-mode inductor 111 can generate a zero-crossing detection signal according to the power supply voltage Vin provided by the input circuit, and transmit it to the PFC chip 130 through the first resistor R1, so that the PFC chip 130 can control the energy storage and discharge process of the common-mode inductor 111.

[0065] For example, when the switch tube in the PFC chip 130 is turned on, the first end of the switch unit 150 is grounded through the switch tube in the PFC chip 130, the path between the common-mode inductor 111 and the output circuit is disconnected, and the common-mode inductor 111 can store energy; for another example, when the switch tube in the PFC chip 130 is turned off, the first end of the switch unit 150 is connected to the common-mode inductor 111, the path between the common-mode inductor 111 and the output circuit is connected, and the common-mode inductor 111 can be discharged to supply power to the external device together with the power supply voltage Vin.

[0066] In some embodiments of this specification, Figure 2 As shown, the common-mode inductor 111 may include: a first common-mode coil LA and a second common-mode coil LB, wherein the first end of the first common-mode coil LA is connected to the input circuit, and the second end of the first common-mode coil LA is respectively connected to the switch unit 150 and the switch tube in the PFC chip 130; the first end of the second common-mode coil LB is grounded, and the second end of the second common-mode coil LB is connected to the first resistor R1.

[0067] Furthermore, using a common-mode inductor as the zero-crossing detection unit 110 can reduce the electromagnetic interference (EMI) signal generated by the circuit itself when the PFC circuit is working and suppress common-mode noise, which can effectively reduce the EMI interference intensity and improve the quality of the output voltage.

[0068] In some embodiments of this specification, Figure 1 , see Figure 3 The structure diagram of a voltage sampling unit in an embodiment of the present disclosure is shown in FIG. Figure 3 As shown, the voltage sampling unit 120 may include: a first sampling module 121 and a second sampling module 122, wherein: a first end of the first sampling module 121 is connected to the input circuit, and a second end thereof is respectively connected to a first end of the second sampling module 122 and the PFC chip 130; a second end of the second sampling module 122 is connected to the PFC chip 130, and a first end and a second end of the second sampling module 122 are connected to different ports in the PFC chip 130.

[0069] By adopting the first sampling module 121 and the second sampling module 122, the amplitude of the voltage output to the PFC chip can be reduced to avoid damage to the PFC chip. And by collecting the voltage value on the input circuit and converting it into a limited value of the input current, it can be ensured that the envelope waveform of the input current follows the sine waveform of the power supply voltage.

[0070] In some embodiments of the present specification, the first sampling module 121 may include a first sampling resistor R2, a second sampling resistor R3 and a third sampling resistor R4, wherein the first end of the first sampling resistor R2 serves as the first end of the first sampling module 121, and the second end of the first sampling resistor R2 is connected to the first end of the second sampling resistor R2; the second end of the second sampling resistor R2 is connected to the first end of the third sampling resistor R3; and the second end of the third sampling resistor R3 serves as the second end of the first sampling module 121.

[0071] In some embodiments of the present specification, the second sampling module 122 may include a fourth sampling resistor R5 and a sampling capacitor C1, wherein a first end of the fourth sampling resistor R5 serves as a first end of the second sampling module 122 and is connected to a first end of the sampling capacitor C1, and a second end of the fourth sampling resistor R5 serves as a second end of the second sampling module 122 and is connected to a second end of the sampling capacitor C1.

[0072] In other words, the voltage value outputted by the voltage sampling unit 120 to the PFC chip 130 may refer to the voltage value on the fourth sampling resistor R5 .

[0073] As an example, the voltage value outputted by the voltage sampling unit 120 to the PFC chip 130 is: R R5 / (R R5 +R R2 +R R3 +R R4 )*Vin, where R R5 represents the resistance value of the fourth sampling resistor R5, R R2 represents the resistance value of the first sampling resistor R2, R R3 represents the resistance value of the second sampling resistor R3, R R4 Indicates the resistance of the third sampling resistor R4.

[0074] Furthermore, by providing the sampling capacitor C1 in the second sampling module 122 , high-frequency noise and interference in the sampling voltage can be filtered out, thereby providing a stable sampling voltage for the PFC chip 130 .

[0075] In some embodiments of this specification, Figure 1 , see Figure 4 The schematic diagram of the structure of a voltage feedback unit in an embodiment of the present disclosure is shown in FIG. Figure 4As shown, the voltage feedback unit 140 may include: a first feedback module 141 and a second feedback module 142, wherein: a first end of the first feedback module 141 is respectively connected to the output circuit and the switch unit 150, and a second end thereof is respectively connected to a first end of the second feedback module 142 and the PFC chip 130; a second end of the second feedback module 142 is connected to the PFC chip 130, and a first end and a second end of the second feedback module 142 are connected to different ports in the PFC chip 130.

[0076] By adopting the first feedback module 141 and the second feedback module 142 , the amplitude of the voltage fed back to the PFC chip can be reduced, thereby preventing the PFC chip from being damaged.

[0077] In some embodiments of the present specification, the first feedback module 141 may include: a first feedback resistor R6, a second feedback resistor R7 and a third feedback resistor R8, the first end of the first feedback resistor R6 serves as the first end of the first feedback module 141, and the second end of the first feedback resistor R6 is connected to the first end of the second feedback resistor R7; the second end of the second feedback resistor R7 is connected to the first end of the third feedback resistor R8; the second end of the third feedback resistor R8 serves as the second end of the first feedback module 141.

[0078] In some embodiments of the present specification, the second feedback module 142 may include a fourth feedback resistor R9, a fifth feedback resistor R10 and a feedback capacitor C2, the first end of the fourth feedback resistor R9 serves as the first end of the second feedback module 142 and is connected to the first end of the feedback capacitor C2, the second end of the fourth feedback resistor R9 is connected to the first end of the fifth feedback resistor R10, and the second end of the fifth feedback resistor R10 serves as the second end of the second feedback module 142 and is connected to the second end of the feedback capacitor C2.

[0079] In other words, the voltage value fed back to the PFC chip 130 by the voltage feedback unit 140 may refer to the voltage value across the fourth feedback resistor R9 and the fifth feedback resistor R10 .

[0080] As an example, the voltage value fed back to the PFC chip 130 by the voltage feedback unit 140 is: (R R9 +R R10 ) / (R R6 +R R7 +R R8 +R R9 +R R10 )*Vout, where R R6 represents the resistance value of the first feedback resistor R6, R R7 represents the resistance value of the second feedback resistor R7, R R8 represents the resistance value of the third feedback resistor R8, R R9 represents the resistance value of the fourth feedback resistor R9, RR10 represents the resistance value of the fifth feedback resistor R10.

[0081] Furthermore, by providing the feedback capacitor C2 in the second feedback module 142 , high-frequency noise and interference in the feedback voltage can be filtered out, thereby providing a stable voltage output.

[0082] In some embodiments of this specification, see Figure 5 The switch unit 150 may include a switch diode D0, wherein a first end of the switch diode D0 is respectively connected to the zero-crossing detection unit 110 and the switch tube in the PFC chip 130, and a second end thereof is used as an output end and is connected to the voltage feedback unit 140.

[0083] Since one end of the switch tube in the PFC chip 130 is grounded, when the switch tube in the PFC chip 130 is turned on, the switch diode D0 is turned off, and the path between the zero-crossing detection unit 110 and the output circuit is disconnected; when the switch tube in the PFC chip 130 is turned off, the switch diode D0 is turned on, and the path between the zero-crossing detection unit 110 and the output circuit is enabled.

[0084] In a specific implementation, according to actual application scenarios and requirements, the PFC circuit in the embodiment of this specification can be further expanded to further improve the stability of the output voltage.

[0085] See also Figure 5 A specific structural diagram of a PFC branch in an embodiment of the present disclosure is shown in FIG. Figure 5 As shown, the PFC branch 100 may further include: a compensation unit 160, which is coupled to the PFC chip 130 and the voltage feedback unit 140 respectively, and is suitable for compensating the output voltage.

[0086] By providing the compensation unit 160 , the output voltage loop can be compensated.

[0087] In some embodiments of the present specification, the compensation unit 150 may include: a first compensation capacitor C3, a second compensation capacitor C4 and a first compensation resistor R11, the first end of the first compensation capacitor C3 is respectively connected to the first end of the first compensation resistor R11 and the PFC chip 130, and the second end thereof is respectively connected to the second end of the second compensation capacitor C4 and the voltage feedback unit 140; the second end of the first compensation resistor R11 is connected to the first end of the second compensation capacitor C4.

[0088] Specifically, when the output voltage is out of the normal range for some reason (for example, the voltage is too low or the voltage is too high), the output voltage can be compensated through the first compensation capacitor C3, the second compensation capacitor C4 and the first compensation resistor R11. For example, if the output voltage is too low, the electric energy stored in the first compensation capacitor C3 and the second compensation capacitor C4 can be released to increase the output voltage; if the output voltage is too high, part of the voltage can be consumed by the first compensation resistor R11 to reduce the output voltage.

[0089] See next Figure 5 The PFC branch may further include a filtering unit 170 coupled to the PFC chip 130, adapted to balance a low frequency (eg, 50 Hz or 60 Hz) of an input signal and a high frequency (eg, up to kilohertz) of an output signal.

[0090] In some embodiments of the present specification, the filtering unit 160 may include a third filter capacitor C5, a fourth filter capacitor C6 and a fifth filter capacitor C7, the first end of the third filter capacitor C5 is respectively connected to the first end of the fourth filter capacitor C6 and the first end of the fifth filter capacitor C7, and is connected to the PFC chip 130; the second end of the third filter capacitor C5 is respectively connected to the second end of the fourth filter capacitor C6 and the second end of the fifth filter capacitor C7, and is connected to the PFC chip 130; wherein the first end of the third filter capacitor C5, the first end of the fourth filter capacitor C6 and the first end of the fifth filter capacitor C7 are respectively connected to different ports of the PFC chip 130.

[0091] Specifically, the third filter capacitor C5 is a bypass capacitor of the linear voltage regulator circuit in the PFC chip 130, the fourth filter capacitor C6 is a bypass capacitor of the power supply PIN pin of the PFC chip 130, and the fifth filter capacitor C7 is a bypass capacitor of the reference voltage PIN pin of the PFC chip 130. By setting capacitors on these three PIN pins respectively, the noise on the circuit can be filtered out, thereby improving the performance of the PFC chip 130.

[0092] See next Figure 5 The PFC branch may further include a soft start unit 180 coupled to the PFC chip 130 and the voltage feedback unit 140 respectively.

[0093] In some embodiments of the present specification, the soft start unit 180 may include a start resistor R12, so that when the PFC branch is just started, the soft start of the PFC branch can be achieved by setting the soft start unit 180, thereby improving the safety of the entire PFC branch.

[0094] See next Figure 5 The PFC branch may further include a discharge unit 190 coupled to the PFC chip 130 and adapted to discharge the X capacitor ( Figure 5This can reduce the power consumption of the PFC branch when it is unloaded.

[0095] In some embodiments of the present specification, the discharge unit 180 may include a first discharge resistor R13 and a second discharge resistor R14 electrically connected to the PFC chip 130 respectively.

[0096] In some optional examples, the PFC chip can also be powered directly. Based on this, see Figure 5 The PFC circuit may further include a power supply branch 200 coupled to the PFC branch and suitable for providing a driving voltage to the PFC chip 130 .

[0097] In some embodiments, when at least one PFC branch is a plurality of PFC branches, the power supply branch 200 provides a driving voltage for a plurality of PFC chips 130 , and the plurality of PFC chips are coupled to each other and work in a time-sharing manner.

[0098] For example, see Figure 5 When at least one PFC branch is a plurality of PFC branches, the pins on the PFC chip 130 for connecting the first compensation resistor R11 and the first compensation capacitor C3 can be connected to the pins of other PFC chips, so that after the PFC chip 130 works for a predetermined period of time, it stops working and another PFC chip starts working, thereby realizing the patrol work between the plurality of PFC branches, thereby improving the output power. For example, in a specific example, at least one PFC branch is a first PFC branch and a second PFC branch, and the first PFC branch and the second PFC branch work in turn, so that the output power of the PFC circuit can be 370W.

[0099] In some embodiments of the present specification, the power supply branch 200 may include a first resistor R15, a first capacitor C8, a first switch tube T1, a first clamping diode ZD1, a second switch tube T2, a second resistor R16 and a second capacitor C9, wherein: a first end of the first resistor R15 is connected to the PFC chip 130, and a second end of the first resistor R15 is respectively connected to a first end of the first capacitor C8 and a first end of the first switch tube T1; a second end of the second capacitor C8 is respectively connected to a first end of the first clamping diode ZD1 and a second end of the second capacitor C9; a control end of the first switch tube T1 is respectively connected to a second end of the first clamping diode ZD1 and a first end of the second switch tube T2, and a second end of the first switch tube T1 is respectively connected to a first end of the second resistor R16 and a first end of the second capacitor C9, and connected to a voltage VCC; a second end of the first switch tube T1 is connected to a second end of the second resistor R16.

[0100] In some embodiments of the present specification, it is considered that when the PFC circuit is powered on, the PFC chip may not start working yet, and a line short circuit may occur at this time.

[0101] Based on this, see Figure 5 The PFC branch may further include: an alternative branch 191, coupled to the input circuit and the output circuit, suitable for connecting the path between the input circuit and the output circuit to charge the output circuit with a supply voltage.

[0102] In some embodiments of the present specification, the alternative branch 191 may include a gate diode D1.

[0103] In the process of storing electric energy in the zero-crossing detection unit, in order to realize power supply to the external device, the device pre-stored in the output circuit can provide voltage to the external device.

[0104] For example, see Figure 5 , a plurality of parallel storage capacitors are arranged on the input branch (for example Figure 5 The energy storage unit is composed of storage capacitors C10 to C12 as shown in the figure. In this way, during the process of storing electric energy in the zero-crossing detection unit, multiple storage capacitors can be used to power external devices.

[0105] More specifically, when the PFC circuit is powered on and the PFC chip 130 has not yet started working, the supply voltage can quickly charge the energy storage unit to avoid the extreme scenario of the PFC line working in an output short circuit, and also avoid the output short circuit protection function of the chip being mistakenly triggered at the moment of startup.

[0106] In some optional examples, the PFC branch may further include: a power limiting unit coupled to the PFC chip 130 to limit the output power of the PFC branch by adjusting its own resistance.

[0107] In this embodiment, the power limiting unit may include a limiting resistor R1X, and the maximum output power of the PFC branch can be determined by setting the resistance value of the limiting resistor R1X. Therefore, the PFC circuit in the above example can be used to widen the output range of the PFC circuit and improve the stability of the output voltage.

[0108] In some embodiments of the present specification, the PFC circuit in the aforementioned embodiments may be applied to various power electronic devices.

[0109] As an example, the PFC circuit in any of the above embodiments may be applied to a charger to charge a device to be charged.

[0110] Reference Figure 6 The schematic diagram of the structure of a charger in the embodiment of this specification is shown in FIG. Figure 6 As shown, in some embodiments of this specification, the charger 300 may include: the PFC circuit 310 and the voltage conversion circuit 320 described in any of the above embodiments, wherein:

[0111] The PFC circuit 310 is adapted to convert the supply voltage provided by the input circuit into an output voltage;

[0112] The voltage conversion circuit 320 is coupled to the PFC circuit 310 and is adapted to convert the type and amplitude of the output voltage output by the PFC circuit 310 and output a target voltage.

[0113] The specific structure and voltage regulation principle of the PFC circuit 310 can be found in the above content and will not be described in detail here.

[0114] Specifically, by widening the output range of the PFC circuit, after conversion by the voltage conversion circuit 320 , the amplitude range of the target voltage can be widened and the stability of the target voltage can be improved.

[0115] In some embodiments of the present specification, the voltage conversion circuit 320 includes a plurality of voltage conversion branches (eg, a plurality of voltage conversion branches connected in parallel), each of which is coupled to at least one PFC branch in the PFC circuit.

[0116] For ease of understanding, the working principle of the voltage conversion circuit 320 is briefly described by taking one of the PFC branches in the voltage conversion circuit 320 as an example. In some embodiments, the charger may have two PFC circuits 310 and four voltage conversion circuits 320, wherein the output ends of the two PFC circuits are connected in parallel to the input ends of each voltage conversion circuit 320.

[0117] See also Figure 7 The schematic diagram of the structure of a voltage conversion branch in the embodiment of this specification is shown in FIG. Figure 7 As shown, the voltage conversion branch may include: a voltage transformation unit 321, a control chip 322 and a gating unit 323, wherein:

[0118] The voltage transformation unit 321 is coupled to the PFC circuit 310 and the control chip 322, and is adapted to convert the type and amplitude of the output voltage to obtain a target voltage when the switch tube in the control chip 322 is in the on state;

[0119] The control chip 322 is coupled to the gating unit 323 and is adapted to convert the target voltage into a current value, and when it is determined that the current value is greater than a preset current, turn off the switch tube in the control chip 322 and output a control signal to the gating unit 323;

[0120] The gating unit 323 is coupled to the voltage transformation unit 321 and is adapted to gating a path between the voltage transformation unit 321 and the ground according to a control signal to output a target voltage.

[0121] Specifically, when the voltage transformation unit 321 is connected to the PFC circuit 310, if the switch tube in the control chip 322 is in the on state, the PFC circuit 310 can supply power to the voltage transformation unit 321, and then the output voltage of the PFC circuit 310 can be converted (including the type and amplitude of the output voltage) to obtain the target voltage. In this process, the current value corresponding to the converted target voltage gradually increases. When the current value increases to be greater than the preset current, the control chip 322 can turn off the switch tube in the control chip 322 and output a control signal to the gating unit 323, so that the gating unit 323 can gating the path between the voltage transformation unit 321 and the ground, and then the target voltage can be output.

[0122] In some embodiments of the present specification, the transformation unit 321 may be implemented by a transformer.

[0123] As an alternative example, see Figure 7 The transformation unit 321 may include a first transformer TR1 and a second transformer TR2, wherein the first end of the first transformer TR1 is connected to the PFC circuit 310 and the second end is grounded; the first end of the second transformer TR2 is connected to the charging device and the second end is connected to the gating unit 323. By gating the gating unit 323, the target voltage can be output.

[0124] In some embodiments of this specification, see Figure 5 In the case where the PFC circuit includes a power supply branch 200, see Figure 7 The transformation unit 321 may include a third transformer TR3, and the charger may further include: a power supply unit 324, wherein a first end of the third transformer TR3 is connected to the PFC circuit 310, and a second end thereof is connected to the power supply unit 324, and is suitable for converting the target voltage into an operating voltage; the power supply unit 324 is suitable for connecting the path between the third transformer TR3 and the power supply branch 200 to output the operating voltage to the power supply branch 200.

[0125] Specifically, when the transformation unit 321 includes the third transformer TR3, the third transformer TR3 and the second transformer TR2 interact to convert the target voltage into the supply voltage, and output the supply voltage to the power supply branch 200 through the power supply unit 324 to power the PFC chip.

[0126] In some embodiments of the present specification, the power supply unit 324 may include a first power supply resistor R20, a first power supply diode D5, a first power supply capacitor C15, a second power supply resistor R21, a second power supply diode D6 and a second power supply capacitor C16, wherein: the first end of the first power supply resistor R20 is respectively connected to the first end of the first power supply diode D5 and the second end of the third transformer TR3, and the second end of the first power supply resistor R20 is connected to the first end of the first power supply capacitor C15; the second end of the first power supply diode D5 is respectively connected to the second end of the first power supply capacitor C15 and the first end of the second power supply resistor R21; the second end of the second power supply resistor R21 is respectively connected to the first end of the second power supply diode D6 and the first end of the second power supply capacitor C16; the second section of the second power supply diode D6 is connected to the power supply branch 200; and the second end of the second power supply capacitor C16 is connected to the control chip 322.

[0127] In some optional examples, the second power supply capacitor C16 can be connected to the control chip 322 through the connecting capacitor C17 to filter out interference signals and improve the stability of the voltage conversion branch.

[0128] In some embodiments of this specification, see Figure 7 The voltage conversion branch may further include an absorption unit 325 coupled between the PFC circuit and the voltage transformation unit 321, and adapted to filter voltage spikes on the voltage conversion branch.

[0129] Therefore, by absorbing the voltage spike caused by the voltage transformation unit 321, it is ensured that the voltage conversion branch can operate in a safe voltage range, and at the same time, the influence of the voltage spike on the radiation of the entire product is weakened.

[0130] In some embodiments, the absorption unit 325 may be implemented by an RCD circuit.

[0131] For details, see Figure 7The absorption unit 325 may include a first absorption capacitor C14, a first absorption resistor R17, a second absorption resistor R18, a third absorption resistor R19, a first absorption diode D2, a second absorption diode D3 and a third absorption diode D4, wherein: the first end of the first absorption capacitor C14 is respectively connected to the PFC circuit, the first end of the first absorption resistor R17, the first end of the first absorption diode D2 and the transformer unit 321, the second end of the first absorption capacitor C14 is respectively connected to the second end of the first absorption resistor R17, the first end of the second absorption resistor R18, and the first end of the third absorption resistor R19; the second end of the first absorption diode D2 is connected to the first end of the second absorption diode D3, the first end of the second absorption diode D3 is respectively connected to the first end of the third absorption diode D4 and the conversion unit 321; the second end of the third absorption diode D4 is respectively connected to the second end of the second absorption resistor R18 and the second end of the third absorption resistor R19.

[0132] In some implementations, in order to reduce the interference of the noise in the output voltage to the voltage conversion branch, see Figure 7 The voltage conversion branch may further include a filter capacitor C13 coupled between the output terminal and the PFC circuit.

[0133] In some embodiments of the present specification, the selection unit 323 may include: a first switching device P1 and a second switching device P2, the first end of the first switching device P1 is connected to the first end of the second switching device P2, and is connected to the control chip 322; the second end of the first switching device P1 is respectively connected to the transformation unit 321 and the second end of the second switching device P2; the third end of the first switching device P1 is connected to the third end of the second switching device P2, and is grounded.

[0134] In some embodiments of the present specification, the inventors further discovered that when the first switch device P1 and the second switch device P2 are turned off, a spike voltage is generated. When the spike voltage is too large, abnormal problems may occur.

[0135] Based on this, see Figure 7 The voltage conversion branch may further include an elimination unit 327 coupled between the output terminal of the voltage conversion branch and the ground, wherein the elimination unit 327 includes: a first elimination capacitor C18, a first elimination resistor R25, a second elimination resistor R26, a first elimination switch P4, a third elimination resistor R27, a first elimination clamping diode ZD2, a fourth elimination resistor R28, a second elimination capacitor C20, a third elimination capacitor C21, a first elimination diode D7, a fourth elimination capacitor C19, a fifth elimination resistor R24, and a second elimination diode D8, wherein the connection relationship is as follows:

[0136] The first end of the first elimination capacitor C18 is respectively connected to the first end of the transformer unit 321, the third end of the first elimination switch P4, the first end of the third elimination resistor R27, the second end of the first elimination clamping diode ZD2, the first end of the second elimination capacitor C20 and the first end of the third elimination capacitor C21, and serves as an output end; the second end of the first elimination capacitor C18 is respectively coupled to the first end of the second elimination resistor R26, the first end of the first elimination resistor R25, and the second end of the first elimination diode D7. The second end of the first elimination resistor R25 is respectively connected to the second end of the second elimination resistor R26 and the second end of the first elimination switch P4.

[0137] The first end of the first elimination switch P4 is respectively connected to the second end of the third elimination resistor R27 , the first end of the fourth elimination resistor R28 , and the first end of the first elimination clamping diode ZD2 .

[0138] The fourth elimination resistor R28 is connected to the second end of the second elimination capacitor C20 , the second end of the third elimination capacitor C21 , and the third end of the gating unit 323 , respectively.

[0139] A first end of the first elimination diode D7 is connected to a first end of the fourth elimination capacitor C19 , a second end of the second elimination diode D8 , and a second end of the gating unit 323 , respectively.

[0140] A first end of the fifth elimination resistor R24 ​​is connected to a second end of the fourth elimination capacitor C19 , a first end of the second elimination diode D8 , and a third end of the gating unit 323 , respectively.

[0141] In some embodiments of the present specification, the voltage conversion branch may also include: a feedback unit 326 composed of a first feedback capacitor C22, a second feedback capacitor C23, a sixth feedback resistor R29 and a seventh feedback resistor R30, wherein: the first end of the first feedback capacitor C22 is connected to the control chip 322, and the first end of the first feedback capacitor C22 is respectively connected to the first end of the sixth feedback resistor R29 and the first end of the second feedback capacitor C23; the second end of the second feedback capacitor C23 is connected to the second end of the seventh feedback resistor R30; the second end of the sixth feedback resistor R29 is connected to the first end of the seventh feedback resistor R30 and is grounded. In some embodiments of the present specification, the voltage conversion branch may also include a shutdown unit composed of a third switch tube P3, a shutdown R22 and a shutdown C17. Specifically, when the output is lightly loaded, the power supply of the PFC part is turned off to stop working and reduce the no-load power consumption.

[0142] Although the embodiments of this specification are disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A PFC circuit, characterized in that: The invention comprises at least one PFC branch coupled between an input circuit and an output circuit, wherein the PFC branch comprises: a zero-crossing detection unit, a voltage sampling unit, a PFC chip, a voltage feedback unit and a switch unit, wherein: The zero-crossing detection unit is coupled to the PFC chip and the switch unit respectively, and is adapted to store the supply voltage provided by the input circuit and generate a zero-crossing detection signal to output to the PFC chip when the switch tube in the PFC chip is turned on; and is adapted to release the stored electric energy through the output circuit when the switch tube in the PFC chip is turned off; The voltage sampling unit is coupled to the PFC chip, and is suitable for collecting the power supply voltage provided by the input circuit, and outputting the sampled voltage to the PFC chip; The voltage feedback unit is coupled to the PFC chip, the output circuit and the switch unit respectively, and is adapted to collect the output voltage on the output circuit and output a feedback voltage to the PFC chip when the switch unit is turned on; The PFC chip is adapted to, when it is determined that the current value corresponding to the zero-crossing detection signal is less than the set current value, turn on the switch tube in the PFC chip so that the switch unit is in an off state; and, when it is determined that the current value corresponding to the zero-crossing detection signal is greater than the set current value, turn off the switch tube in the PFC chip and turn on the switch unit to connect the zero-crossing detection unit with the output circuit; and, according to the sampling voltage and the feedback voltage, adjust the set current value to change the turn-on time of the switch tube in the PFC chip, including: the PFC chip compares the feedback voltage with a preset voltage, and when it is determined that the feedback voltage is greater than the preset voltage, reduces the set current value, and when it is determined that the feedback voltage is less than the preset voltage, increases the set current value.

2. The PFC circuit according to claim 1, characterized in that: The zero-crossing detection unit includes a common-mode inductor and a first resistor, wherein: The first end of the common mode inductor is connected to the input circuit, the second end thereof is grounded, the third end thereof is respectively connected to the switch unit and the switch tube in the PFC chip, and the fourth end thereof is connected to the first end of the first resistor; The second end of the first resistor is connected to the PFC chip.

3. The PFC circuit according to claim 1, characterized in that: The voltage sampling unit includes: a first sampling module and a second sampling module, wherein: a first end of the first sampling module is connected to the input circuit, and a second end thereof is respectively connected to a first end of the second sampling module and the PFC chip; a second end of the second sampling module is connected to the PFC chip; The first sampling module includes a first sampling resistor, a second sampling resistor and a third sampling resistor, the first end of the first sampling resistor serves as the first end of the first sampling module, and the second end of the first sampling resistor is connected to the first end of the second sampling resistor; the second end of the second sampling resistor is connected to the first end of the third sampling resistor; the second end of the third sampling resistor serves as the second end of the first sampling module; The second sampling module includes a fourth sampling resistor and a sampling capacitor, wherein a first end of the fourth sampling resistor serves as a first end of the second sampling module and is connected to a first end of the sampling capacitor, and a second end of the fourth sampling resistor serves as a second end of the second sampling module and is connected to a second end of the sampling capacitor.

4. The PFC circuit according to claim 1, characterized in that: The voltage feedback unit comprises: a first feedback module and a second feedback module, wherein: a first end of the first feedback module is respectively connected to the output circuit and the switch unit, and a second end thereof is respectively connected to a first end of the second feedback module and the PFC chip; a second end of the second feedback module is connected to the PFC chip; The first feedback module includes: a first feedback resistor, a second feedback resistor and a third feedback resistor, wherein the first end of the first feedback resistor serves as the first end of the first feedback module, and the second end of the first feedback resistor is connected to the first end of the second feedback resistor; the second end of the second feedback resistor is connected to the first end of the third feedback resistor; and the second end of the third feedback resistor serves as the second end of the first feedback module; The second feedback module includes: a fourth feedback resistor, a fifth feedback resistor and a feedback capacitor, the first end of the fourth feedback resistor serves as the first end of the second feedback module and is connected to the first end of the feedback capacitor, the second end of the fourth feedback resistor is connected to the first end of the fifth feedback resistor, and the second end of the fifth feedback resistor serves as the second end of the second feedback module and is connected to the second end of the feedback capacitor.

5. The PFC circuit according to any one of claims 1 to 4, characterized in that: The PFC branch further includes: a compensation unit, coupled to the PFC chip and the voltage feedback unit, respectively, and adapted to compensate the output voltage; the compensation unit comprises: a first compensation capacitor, a second compensation capacitor and a first compensation resistor, wherein the first end of the first compensation capacitor is respectively connected to the first end of the first compensation resistor and the PFC chip, and the second end thereof is respectively connected to the second end of the second compensation capacitor and the voltage feedback unit; the second end of the first compensation resistor is connected to the first end of the second compensation capacitor; A filtering unit is coupled to the PFC chip and is suitable for filtering out clutter of the voltage output to the PFC chip; the filtering unit comprises a third filtering capacitor, a fourth filtering capacitor and a fifth filtering capacitor, a first end of the third filtering capacitor, a first end of the fourth filtering capacitor and a first end of the fifth filtering capacitor are respectively connected to different ports of the PFC chip; a second end of the third filtering capacitor is respectively connected to a second end of the fourth filtering capacitor and a second end of the fifth filtering capacitor, and is connected to the PFC chip.

6. The PFC circuit according to any one of claims 1 to 4, characterized in that: Also includes: A power supply branch is coupled to the PFC branch and is suitable for providing a driving voltage for the PFC chip, wherein when at least one of the PFC branches is a plurality of PFC branches, the power supply branch provides a driving voltage for the plurality of PFC chips, and the plurality of PFC chips are coupled to each other and work in time sharing.

7. A charger, characterized in that: include: The PFC circuit according to any one of claims 1 to 6, adapted to convert a supply voltage provided by an input circuit into an output voltage; The voltage conversion circuit is coupled to the PFC circuit and is suitable for converting the type and amplitude of the output voltage output by the PFC circuit and outputting a target voltage.

8. The charger according to claim 7, characterized in that: The voltage conversion circuit includes a plurality of voltage conversion branches, each of which is coupled to at least one PFC branch in the PFC circuit, wherein the voltage conversion branch includes: a voltage transformation unit, a control chip and a gating unit, wherein: The voltage transformation unit is coupled to the PFC circuit and the control chip, and is adapted to convert the type and amplitude of the output voltage to obtain the target voltage when the switch tube in the control chip is in the on state; The control chip is coupled to the gating unit and is adapted to convert the target voltage into a current value, and when it is determined that the current value is greater than a preset current, turn off the switch tube in the control chip and output a control signal to the gating unit; The gating unit is coupled to the voltage transformation unit and is adapted to gating a path between the voltage transformation unit and the ground according to the control signal to output the target voltage.

9. The charger according to claim 8, characterized in that: The gating unit includes: a first switching device and a second switching device, wherein the first end of the first switching device is connected to the first end of the second switching device and is connected to the control chip; the second end of the first switching device is respectively connected to the transformer unit and the second end of the second switching device; the third end of the first switching device is connected to the third end of the second switching device and is grounded.

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