TWI460571B - Power factor control circuit and its control method - Google Patents

Description

Power factor control circuit and control method thereof

The invention relates to a power factor control circuit and a control method thereof, in particular to a control circuit and a control method for outputting a corresponding pulse width modulation signal according to the current current mode of the switching power supply circuit.

Referring to FIG. 5, in order to convert the commercial AC power supply (Vac) into a DC power supply for use by the load 60, a rectifier 50 and a switching power supply circuit 70 are connected between the AC power supply (Vac) and the load 60. The rectifier 50 converts the AC power to a DC sine wave voltage; the input of the switching power supply circuit 70 is connected to the output of the rectifier 50 to convert the DC sine wave voltage into a stable DC power source and outputted to the output terminal thereof. The load 60, wherein the switched power supply circuit 70 includes a power factor correction circuit 71 and a DC/DC converter 72. The DC/DC converter 72 converts the voltage (eg, 380V) output by the power factor correction circuit 71 into The DC voltages of different levels (such as 28V, 12V) are output to the load 60.

The power factor correction circuit 71 mainly includes an inductor L, an output capacitor c and an active switch 711, a first proportional integral amplifier 81, a second proportional integral amplifier 82, a multiplexer 83 and a driver 84; The active switch 711 is connected between the inductor L and the output capacitor C. The active switch 711 has a control terminal.

The first proportional integral amplifier 81 has two input terminals and is respectively connected to the output end of the power factor correction circuit 71 and a reference voltage V _ref1 , and has an output terminal connected to the multiplexer 83, and the multiplexer 83 is connected to the rectifier 50 output.

The second proportional integrating amplifier 82 has two input ends and is respectively connected to the output of the rectifier 50 and the output of the multiplexer 83.

The driver 84 has two input terminals and is electrically connected to the output end of the second proportional integrating amplifier 82 and a reference voltage signal V _ref2 , and the output end of the driver 84 is connected to the control end of the active switch 711 .

The control method of the known power factor is described in conjunction with the above circuit structure. The first proportional integral amplifier 81 outputs a voltage error signal V _error according to the difference between the actual output voltage of the power factor correction circuit 71 and the reference voltage V _ref1 ; the second proportional integral amplifier 82 is based on the inductor current I _L and the voltage error signal V _error outputs a voltage signal I _error representing a current _error to the driver 84, and the driver 84 outputs a pulse width modulation signal to the control terminal of the active switch 711 according to the voltage signal I _error and the reference voltage signal V _ref2 to control The duty cycle of the active switch 711 is turned on (Duty cycle, D).

In the above, if the power factor correction circuit 71 outputs a stable voltage V _out , the duty cycle, the actual input voltage V _{in, sense} and the preset output voltage V _out have a relationship: . The duty cycle of the pulse width modulation signal is based on the voltage signal I _error , and the voltage signal I _error includes the actual input voltage of the power factor correction circuit 71, the component of the inductor current I _L and the actual output voltage, and thus the transmission power. The proper configuration of the factor correction circuit results in an improved power factor.

In summary, as long as there is a difference between the actual output voltage of the power factor correction circuit 71 and the reference voltage V _ref1 , and the difference between the inductor current I _L current of the power factor correction circuit 71 and the voltage error signal V _error The driver 84 can correspond to the output pulse width modulation signal.

Switched power circuits operate in different current modes due to load state changes, including Continuous Current Mode (CCM) and Discrete Current Mode (DCM).

When the switching power supply circuit operates in the continuous current mode, during the duty cycle of the pulse width modulation signal, the active switch 711 is turned on, charging the inductor L, and boosting the current through the inductor L; During the duty cycle of the pulse width modulation signal, the active switch 711 is turned off to discharge the inductor L, and before the inductor L is discharged to zero, the pulse width modulation signal causes the active switch 711 to be turned on again to recharge the inductor L. To a higher current level, during the process of charging and discharging the inductor L, the average current waveform of the inductor L will follow the input voltage waveform.

When the power factor correction circuit 71 operates in the discontinuous current mode, the current is low relative to the continuous current mode; during the duty cycle of the pulse width modulation signal, the active switch 711 is turned on, so that the inductor L is charged to boost the through inductor The current of L; during the duty cycle of the non-pulse width modulated signal, the inductor L will discharge to zero and be charged during the next duty cycle; therefore the average current through inductor L is lower than the continuous current mode.

As shown in FIG. 5, in the circuit structure for improving the power factor, if the duty cycle of the pulse width modulation signal has been designed to conform to the continuous current mode, although it is indeed possible to improve the power factor when operating in the continuous current mode, it also makes the power When the factor correction circuit 71 operates in the discontinuous current mode, the pulse width modulation signal still follows the duty cycle when the continuous current mode is used; the pulse width modulation signal is during the non-responsibility period, and when the inductance L is discharged to zero, the power The capacitive energy stored by the energy storage elements (e.g., diode, boost capacitor C, etc.) on the factor correction circuit 71 is fed back to the input of the power factor correction circuit 71, causing severe harmonic distortion at the input.

In order to improve the above disadvantages, please refer to FIG. 6, which is a modification of the power factor correction circuit 71'. The active switch 711' in the power factor correction circuit 71' is connected in parallel with a vibration relief unit 73. The unit 73 includes a diode 730, a resistor 731 and a capacitor 732. The diode 730 is connected in parallel with the resistor 731 and then connected in series to the capacitor 732. The anode end of the diode 730 is connected to the inductor L. The cathode end is connected to a capacitor 732. Thereby, if the power factor correction circuit 71' operates in the discontinuous current mode, during the non-responsibility period of the pulse width modulation signal, the energy storage component (such as the inductor L and the diode D) on the boosting power supply circuit The part of the stored energy of the boosting capacitor C) will be absorbed by the vibration absorbing unit 73, which effectively reduces the harmonic distortion of the boosting power supply circuit at its input end.

However, the diode 730, the resistor 731 and the capacitor 732 in the buffer unit 73 are passive components, which will consume energy during the conversion of the power factor correction circuit 71, thereby reducing the conversion efficiency of the boost power supply circuit. It will cause low frequency oscillations in the input current.

Please refer to FIG. 7 , the existing researcher proposes a control circuit, which firstly determines the current mode of the current operation of the switching power supply circuit, and then changes the duty cycle of the pulse width modulation signal according to the current current mode.

The control circuit also includes a rectifier 90 and a power factor correction circuit 91; wherein the input of the rectifier 90 is connected to an AC mains (Vac), the input of the power factor correction circuit 91 is electrically connected to the output of the rectifier 90, and The power factor correction circuit 91 includes an inductor L, a capacitor C, an active switch 910, and a power factor controller 92.

The rectifier 90 receives AC mains (Vac), converts the AC mains into a continuous stream power supply, and outputs it.

The input terminal V _{in of} the power factor correction circuit 91 is electrically coupled to the output of the rectifier 90, which is operable in a continuous current mode or a discontinuous current mode; the power factor correction circuit 91 is illustrated by a boost circuit.

The input end of the power factor controller 92 is electrically connected to the input end and the output end of the power factor correction circuit 91 to extract the input voltage V _{in, sense} , the output voltage V _{out, sense} and the inductance of the power factor correction circuit 91 The current I _{L, sense} , and the power factor controller 92 has an output control terminal electrically connected to the active switch 910.

Referring to FIG. 8 , the power factor controller 92 has an operation unit 923 built therein, and the power factor controller 92 includes a continuous current mode 921 and a discontinuous current mode 922 .

According to the characteristic relationship of the power factor correction, the operation unit 923 is based on two arithmetic expressions. as well as The size between the two, if D2 < D1, it is judged as continuous current mode, the power factor controller 92 is switched to the continuous current mode 921, and a duty cycle can be output from the output control terminal thereof. Pulse width modulation signal, wherein a theoretical value, A compensation parameter is determined; if D1 < D2, it is determined to be a discontinuous current mode, and the power factor controller 92 is switched to the discontinuous current mode 921, and a duty cycle can be output from the output control terminal thereof. Pulse width modulation signal, and A theoretical value:

L: inductance value;

V _in,sense : input voltage;

V _{out, sense} : output voltage;

V _out : rated output voltage;

T _s : the period of the pulse width modulation signal.

i _REF : The parameter obtained by proportionally integrating the error value between the output voltage V _{out, sense} and a reference voltage.

Therefore, the power factor controller 92 can actively change the output pulse width modulation signal according to the operation mode of the current power factor correction circuit 91, thereby improving the inability of the pulse width modulation signal to correspond to the power factor correction circuit 91. The state of the harmonics.

When the power factor correction circuit 91 operates in the continuous current mode, the duty cycle includes a theoretical value and a compensation parameter, and the compensation parameter complements the theoretical value; however, when the power factor correction circuit 91 operates in the discontinuous current mode , the duty cycle of the output of the power factor controller 92 It is only a theoretical value. Of course, when the power factor controller 92 switches to the discontinuous current mode 922, only the theoretical value is directly applied to the actual circuit, so the effect of improving the harmonic distortion is limited (as shown in FIG. 9). Input voltage, current waveform diagram), there is room for improvement.

It is therefore a primary object of the present invention to provide a power factor control circuit to improve harmonic distortion defects of known control circuits.

In order to achieve the above, the technical means adopted by the present invention is that the power factor control circuit comprises an inductor, an output capacitor, a diode, an active switch and a power factor controller; wherein the power factor controller is electrically Connecting the input end and the output end of the power factor control circuit, and having an output control end electrically connected to the active switch; the power factor controller operates according to the power factor control circuit in a continuous current mode or a discontinuous current mode, and the corresponding output is different a pulse width modulation signal; wherein: the duty cycle of the pulse width modulation signal corresponding to the continuous current mode output is a sum of a feedforward control parameter and a current compensation parameter; and a pulse width modulation signal corresponding to the discontinuous current mode output The duty cycle is a sum of a feedforward control parameter and a current compensation parameter; wherein the current compensation parameter includes an error value between the reference current and the inductor current.

The present invention further provides a power factor control method, the method comprising: determining that the current current operation mode is a continuous current mode or a discontinuous current mode; if the continuous current mode is determined, outputting a pulse width modulation signal corresponding to the continuous current mode, The duty cycle is a sum of a feedforward control parameter and a current compensation parameter, wherein the current compensation parameter includes an error value of the reference current and the inductor current; if the discontinuous current mode is determined, the corresponding discontinuous current mode The duty cycle is a sum of a feedforward control parameter and a current compensation parameter, wherein the current compensation parameter includes an error value between the reference current and the inductor current.

The control method of the present invention outputs a corresponding pulse width modulation signal to the switching power supply circuit according to different current modes operated by the switching power supply circuit, so as to simultaneously satisfy the load connected to the switching power supply circuit as a heavy load or a light load. The demand is therefore effective in improving harmonics.

1 is a circuit diagram of a power factor control circuit of the present invention, wherein the power factor control circuit 20 is connected to an alternating current power supply (Vac) through a rectifier 10, and the alternating current power is converted into a constant stream power supply by the rectifier 10. Get the DC sine wave power supply at the input. The power factor control circuit 20 can be a boost converter or a buck converter, and can operate in a continuous current mode or a discontinuous current mode. This embodiment is a boost type. For example, the power factor control circuit 20 includes an inductor L, a diode D, an output capacitor C, a resistor R, an active switch 21, and a power factor controller 30.

The inductor L, the diode D, and the output capacitor C are connected in series with the resistor R and form a loop with the rectifier 10; the active switch 21 is electrically connected between the anode end of the diode D and the resistor R, and the active switch 21 having a control terminal; ends of the capacitor C is output as a voltage output terminal V _out; the power factor controller 30 is connected between the input power factor control circuit 20 and the output terminal, and having an output control terminal The control terminal of the active switch 21 is connected.

Referring to FIG. 2 , the power factor controller 30 includes a voltage loop control module 31 , a current loop control module 32 , and a feedforward control module 33 .

The voltage loop control module 31 includes a CCM proportional integral amplification unit 310 and a DCM proportional integral amplification unit 311; the CCM proportional integral amplification unit 310 has a proportional parameter K _{P, CCM} and an integral parameter K _I in the continuous current mode _{. CCM} , the DCM proportional integral amplification unit 311 has a proportional parameter K _{P, DCM} , integral parameter K _{I, DCM} in the discontinuous current mode; the input end of the voltage loop control module 31 is electrically connected to a reference voltage V _ref and the power The input end and the output end of the factor control circuit 20 are used to obtain the difference between the reference voltage V _ref and the output voltage V _{out, sense} of the power factor control circuit 20, and the difference is transmitted through the CCM proportional integral amplification unit 310 or the DCM proportional integral. After the unit 311 performs proportional integral amplification, it is multiplied by the actual input voltage V _{in, sense of the} power factor control circuit 20 to form a signal output representative of the reference current i _REF .

The current loop control module 32 is electrically connected to the output end of the voltage loop control module 31 and the resistor R of the power factor control circuit 20, and has the output control terminal, and the resistance of the power factor control circuit 20 is reflected by the resistor R. Current I _{L, sense} , the current loop control module 32 receives the reference current i _REF and the inductor current I _{L, sense} and subtracts to obtain the difference i _REF -I _{L, sense} ; the current loop control module 32 A continuous current compensation unit 321 and a discontinuous current compensation unit 322 are included, and each of the compensation units 321, 322 respectively generates a current compensation parameter according to the difference; according to the characteristic relationship of the power factor correction, the boost power supply circuit The current compensation parameter generated by the continuous current compensation unit 321 is The current compensation parameter generated by the discontinuous current compensation unit 322 is F _m ( i _REF - I _{L , sense} ), where:

L: inductance value;

V _out : rated output voltage;

I _{L, sense} : inductor current;

F _m : compensation constant;

i _REF : Contains the reference current of the output voltage V _{out, sense} component.

The input end of the feedforward control module 33 is electrically connected to the output end of the voltage loop control module 31 and the output end of the power factor control circuit 20 and the input end. The output control end of the feedforward control module 33 is electrically connected. The current loop control module 32 is connected to the voltage loop control module 33. The feedforward control module 33 is based on the input voltage Vin _{, sense} and the output voltage Vout of the power factor control circuit 20 _{. Sense} and the reference current i _REF output by the voltage loop control module 31 determine that the power factor control circuit 20 operates in a continuous current mode or a discontinuous current mode, and correspondingly switch the CCM in the voltage loop control module 31 according to each current mode. The proportional integral amplification circuit 310 and the DCM proportional integral amplification circuit, and the continuous current compensation unit 321 and the discontinuous current compensation unit 322 in the corresponding switching current loop control module 32; the feedforward control module 33 generates a corresponding current mode Feeding control parameters to the current loop control module 32; the current loop control module 32 outputs a pulse width modulation signal to the active start end 21, wherein the pulse width adjustment Duty cycle signals that is the sum of the feedforward control and the current parameters of the current loop compensation parameter control module 31 generating the front.

As described in the prior art, in the general judgment mode, the feedforward control module 33 is based on two arithmetic expressions. as well as The size between the two, if D1 < D2, it is judged that the boost power supply circuit operates in the discontinuous current mode, and according to the characteristic relationship of the power factor correction, the generated feedforward control parameter is If D2<D ₁ , it is judged as continuous current mode, and the generated feedforward control parameter is . among them:

L: inductance value;

V _in,sense : input voltage;

V _{out, sense} : output voltage;

V _out : rated output voltage;

T _s : the period of the pulse width modulation signal.

For example, when the feedforward control module 33 determines that the power factor control circuit 20 is operating in the continuous current mode, the voltage loop control module 31 is switched to the CCM proportional integral amplification unit 310 to output the voltage loop control module 31. The proportional parameter K _{P, CCM} and the integral parameter K _{I, CCM} , and the current loop control module 32 are switched to the continuous current compensation unit 321 , so that the continuous current compensation unit 321 generates the current compensation parameter as The feedforward control module 33 generates feedforward control parameters And feeding the feedforward control parameter to the current loop control module 32, the current loop control module 32 adds the feedforward control parameter and the current compensation parameter, and outputs a duty cycle of The pulse width modulation signal is sent to the control end of the active switch 21, and the duty cycle is the sum of the feedforward control parameter and the current compensation parameter.

Similarly, when the feedforward control module 33 determines that the power factor control circuit 20 is operating in the discontinuous current mode, the feedforward control module 33 switches the voltage loop control module 31 to the DCM proportional integral amplification unit 311, and switches the current. The loop control module 32 to the discontinuous current compensation unit 322, the current loop control module 32 outputs a duty cycle of The pulse width modulation signal is to the control end of the active switch 21.

In summary, the feedforward controller 33 can determine which current mode the power factor control circuit 20 operates in, and corresponding to the proportional integral amplification unit and the current loop control module 32 in the switching voltage loop control module 31. The current compensation unit causes the current loop control module 32 to output a corresponding pulse width modulation signal to the active switch 21 according to each current mode, wherein the pulse width modulation signal in each current mode is mainly used to detect the power factor. The difference between the inductor current I _{L, sense of the} control circuit 20 and the reference current i _REF output by the voltage loop control module 31 (i _{REF -} I _{L, sense} ) to generate a current compensation parameter; 3, Figure 9 (waveform diagram of the prior art) and Table 1 below, Figure 3 is the AC voltage and current waveform diagram of the circuit of the present invention in the discontinuous current mode, as can be seen from the figure, the input of the circuit of the present invention The current I _{ac is} closer to the waveform of the input voltage V _ac . Compared with the prior art, in the discontinuous current mode, the duty cycle of the pulse width modulation signal is According to the difference between the actual inductor current I _{L, sense} and the reference current i _REF , the duty cycle is not only the theoretical value, so the problem of power factor and harmonics can be more effectively improved.

Referring to FIG. 4, in another preferred embodiment, the power factor control circuit 20' is a buck converter, including an active switch 21', a diode D, and an inductor L. An output capacitor C and a power factor controller 30'; the active switch 21', the inductor L, the output capacitor C are connected in series and form a loop with the rectifier 10', and the active switch 21' has a control end, The anode end of the diode D is connected to the output end of the rectifier 10', and the cathode end thereof is connected between the active switch 30' and the inductor L. The power factor controller 30' is connected to the output and input of the power factor control circuit 20'. And an output control terminal is connected to the control end of the active switch 21'.

The control method of the preferred embodiment is used to determine the continuous, discontinuous current mode of the operating system If D1 < D2, it is determined that the power factor control circuit 20' operates in the discontinuous current mode. If D2 < D1, it is determined that the power factor control circuit 20' operates in the continuous current mode; and if the power factor control circuit 20' operates in In the discontinuous current mode, the feedforward control parameter generated by the feedforward controller in the power factor controller 30' is The current compensation parameter is F _m ( i _REF - I _{L , sense} ), so the duty cycle of the pulse width modulation signal is If the power factor control circuit 20' operates in the continuous current mode, the feedforward control parameter generated by the feedforward controller in the power factor controller 30' is And the current compensation parameter is Therefore, the duty cycle of the pulse width modulation signal is . among them:

L: inductance value;

V _in,sense : input voltage;

V _{out, sense} : output voltage;

V _out : rated output voltage;

Ts: the period of the pulse width modulation signal;

i _REF : Contains the reference current of the output voltage V _{out, sense} component.

10. . . Rectifier

10’. . . Rectifier

20. . . Power factor control circuit

20’. . . Power factor control circuit

twenty one. . . Active switch

twenty one'. . . Active switch

30. . . Power factor controller

30’. . . Power factor controller

31. . . Voltage loop control module

310. . . CCM proportional integral amplification unit

311. . . DCM proportional integral amplification unit

32. . . Current loop control module

321. . . Continuous current compensation unit

322. . . Discontinuous current compensation unit

33. . . Feedforward control module

50, 50’. . . Rectifier

60. . . load

70. . . Switched power supply circuit

71, 71’. . . Power factor correction circuit

711, 711’. . . Active switch

72. . . DC/DC converter

73. . . Vibration relief unit

730. . . Dipole

731. . . resistance

732. . . capacitance

81. . . First proportional integral amplifier

82. . . Second proportional integral amplifier

83. . . Multiplexer

84. . . driver

90. . . Rectifier

91. . . Switched power supply circuit

910. . . Active switch

92. . . Power factor controller

921. . . Continuous current mode

922. . . Discontinuous current mode

923. . . Arithmetic unit

Figure 1: Schematic diagram of the connection of the boost power supply circuit and the power factor controller.

Figure 2: Detailed schematic diagram of the power factor controller.

Figure 3: Current-compensated input voltage and current waveforms.

Figure 4: Connection diagram of the buck power supply circuit and power factor controller.

Figure 5: Schematic diagram of the known switched power supply circuit and power factor control circuit connection.

Figure 6: Schematic diagram of another known switched power supply circuit and power factor controller connection.

Figure 7: A schematic diagram of another known switched power supply circuit and power factor controller connection.

Figure 8: Schematic diagram of the power factor controller in Figure 7.

Figure 9: Schematic diagram of the input voltage and current waveforms of the switched power supply circuit in Figure 7.

twenty one. . . Active switch

30. . . Power factor controller

31. . . Voltage loop control module

310. . . CCM proportional integral amplification unit

311. . . DCM proportional integral amplification unit

32. . . Current loop control module

321. . . Continuous current compensation unit

322. . . Discontinuous current compensation unit

33. . . Feedforward control module

Claims (10)

A power factor control circuit includes an inductor, an output capacitor, a diode, an active switch, and a power factor controller; wherein the power factor controller is electrically connected to an input end and an output end of the power factor control circuit And having an output control terminal electrically connected to the active switch; the power factor controller correspondingly outputs different pulse width modulation signals according to the power factor control circuit operating in a continuous current mode or a discontinuous current mode; wherein: corresponding continuous current mode The duty cycle of the output pulse width modulation signal is a sum of a feedforward control parameter and a current compensation parameter; the duty cycle of the pulse width modulation signal corresponding to the discontinuous current mode output is a feedforward control parameter and a a sum of current compensation parameters, wherein the current compensation parameter is a reference current and an inductor current multiplied by a compensation constant; the power factor controller includes: a voltage loop control module, which is controlled according to the power factor The difference between the output voltage of the circuit and a reference voltage produces the reference current, which includes a CCM proportional integral a large unit and a DCM proportional integral amplification unit; a current loop control module electrically connecting the output end of the voltage loop control module and the power factor control circuit for outputting a pulse width modulation signal to the active switch, The invention comprises a continuous current compensation unit and a discontinuous current compensation unit, respectively generating the current compensation parameter according to the inductor current of the power factor control circuit; a feedforward control module, wherein the input end is electrically connected to the voltage loop control An output end of the module and an output end and an input end of the power factor control circuit, an output control terminal of the feedforward control module is electrically connected to the current loop control module, and another output control terminal is electrically connected to the voltage loop control The feedforward control module determines that the power factor control circuit operates in a continuous current mode or a discontinuous current mode, and generates the feedforward control parameter corresponding to the current loop control module according to each current mode, and corresponds to a CCM proportional integral amplification unit and a DCM proportional integral amplification unit in the switching voltage loop control module, and a continuous current compensation unit and a discontinuous current compensation unit in the switching current loop control module, so that the current loop control module outputs a pulse width The duty cycle of the modulation signal is the sum of the feedforward control parameter and the current compensation parameter. The power factor control circuit of claim 1, wherein the inductor, the diode, and the output capacitor are connected in series and form a loop with a rectifier, and the active switch is electrically connected to the anode end of the diode and the anode Between the output ends of the rectifier, the current loop control module has the output control terminal; wherein: the duty cycle of the pulse width modulation signal is in continuous current mode , wherein the feedforward control parameter is , the current compensation parameter is The duty cycle of the pulse width modulation signal is in the discontinuous current mode. , wherein the feedforward control parameter is The current compensation parameter is F _m ( i _REF -I _L,sense ), where: L: inductance value; V _{in, sense} : input voltage; V _{out, sense} : output voltage; V _out : rated output voltage; I _{L. Sense} : inductor current; T _s : the period of the pulse width modulation signal; F _m : compensation constant; i _REF : the reference current including the output voltage V _{out, sense} component. For example, the power factor control circuit described in claim 2, the feedforward control module is based on two arithmetic expressions as well as The size between the two, if D1 < D2, it is judged that the power factor control circuit operates in the discontinuous current mode; if D2 < D1, it is determined as the continuous current mode, wherein: L: inductance value; V _{in, sense} : input voltage V _{out, sense} : output voltage; T _s : the period of the pulse width modulation signal; i _REF : the reference current including the output voltage V _{out, sense} component. The power factor control circuit of claim 1, wherein the active switch, the inductor, the output capacitor are connected in series and form a loop with a rectifier, and the active switch has a control end, and an anode end of the diode Connected to the output end of the rectifier, the cathode end of which is connected between the active switch and the inductor, the current loop control module has the output control terminal; wherein: the duty cycle of the pulse width modulation signal is in continuous current mode , wherein the feedforward control parameter is , the current compensation parameter is The duty cycle of the pulse width modulation signal is in the discontinuous current mode. , wherein the feedforward control parameter is The current compensation parameter is F _m ( i _REF -I _L,sense ), where: L: inductance value; V _{in, sense} : input voltage; V _{out, sense} : output voltage; V _out : rated output voltage; Ts: pulse The period of the wide-adjusted signal; i _REF : contains the reference voltage of the output voltage V _{out, sense} component. The power factor control circuit according to item 4 of the patent application scope, the feedforward control module is based on two arithmetic expressions , If D1 < D2, it is determined that the power factor control circuit operates in the discontinuous current mode. If D2 < D1, it is determined to be a continuous current mode; wherein: L: inductance value; V _{in, sense} : input voltage; V _{out, Sense} : output voltage; Ts: period of pulse width modulation signal; i _REF : reference current containing output voltage V _{out, sense} component. A power factor control method includes the following steps: determining that the current current operation mode is a continuous current mode or a discontinuous current mode; if it is determined to be a continuous current mode, outputting a pulse width modulation signal corresponding to the continuous current mode, the duty cycle is a sum of a feedforward control parameter and a current compensation parameter, wherein the current compensation parameter includes an error value between the reference current and the inductor current; if the discontinuous current mode is determined, the discontinuous current mode corresponds to a pulse width The modulation signal has a duty cycle which is a sum of a feedforward control parameter and a current compensation parameter, wherein the current compensation parameter includes an error value between the reference current and the inductor current. As described in the power factor control method of claim 6, the duty cycle of the pulse width modulation signal in the continuous current mode is , wherein the feedforward control parameter is , the current compensation parameter is The duty cycle of the pulse width modulation signal described above for the discontinuous current mode is , wherein the feedforward control parameter is The current compensation parameter is F _m ( i _REF -I _L,sense ), where: L: inductance value; V _{in, sense} : input voltage; V _{out, sense} : output voltage; V _out : rated output voltage; I _{L, Sense} : inductor current; T _s : the period of the pulse width modulation signal; F _m : compensation constant; i _REF : the reference current including the output voltage V _{out, sense} component. The power factor control method according to item 7 of the patent application scope is based on the two arithmetic expressions in the step of judging that the current current operation mode is the continuous current mode or the discontinuous current mode. as well as The size between the two, if D1 < D2, it is judged that the power factor control circuit operates in the discontinuous current mode; if D2 < D1, it is determined as the continuous current mode, wherein: L: inductance value; V _{in, sense} : input voltage V _{out, sense} : output voltage; T _s : the period of the pulse width modulation signal; i _REF : the reference current including the output voltage V _{out, sense} component. As described in the power factor control method of claim 6, the duty cycle of the pulse width modulation signal in the continuous current mode is , wherein the feedforward control parameter is , the current compensation parameter is The duty cycle of the pulse width modulation signal described above for the discontinuous current mode is , wherein the feedforward control parameter is The current compensation parameter is F _m ( i _REF -I _L,sense ), where: L: inductance value; V _{in, sense} : input voltage; V _{out, sense} : output voltage; V _out : rated output voltage; Ts: pulse The period of the wide-adjusted signal; i _REF : contains the reference voltage of the output voltage V _{out, sense} component. For example, in the power factor control method described in claim 9 of the patent application, in the step of judging that the current current operation mode is the continuous current mode or the discontinuous current mode, the two arithmetic expressions are , If D1 < D2, it is determined that the power factor control circuit operates in the discontinuous current mode. If D2 < D1, it is determined in the continuous current mode; wherein: L: inductance value; V _{in, sense} : input voltage; V _{out, Sense} : output voltage; Ts: period of pulse width modulation signal; i _REF : reference current containing output voltage V _{out, sense} component.