Input impedance based full load power factor correction converter and control method

Abstract

The application discloses an input impedance-based full-load power factor correction converter and a control method. Firstly, the off duty cycle of the converter is calculated in the input impedance-based control mode, and then the on duty cycle of the converter is obtained. Secondly, in the DCM mode, the DCM compensation coefficient is obtained by acquiring the proportion of the time when the inductor current is greater than 0 in a switching cycle. Finally, the on duty cycle is compensated based on the DCM compensation coefficient. Based on the relationship between the compensated on duty cycle and the PWM carrier, the PWM control signal is generated and outputted, so that the converter can work in the DCM mode and the CCM mode naturally.

Description

Technical Field

[0001] This invention relates to the field of converter technology, and more specifically to a full-load power factor correction converter and control method based on input impedance. Background Technology

[0002] In fixed-frequency, continuous-current power factor correction (PFC) control, good harmonic current distortion (ithd) and power factor (PF) are typically only achieved under medium to high load conditions. However, under high-voltage input or light-load conditions, the inductor current in the converter cannot remain in a continuous current state (CCM mode: continuous conduction mode), but rather operates in a discontinuous current state (DCM mode: discontinuous conduction mode). This significantly affects the power factor correction control effect under high-voltage or light-load conditions, leading to increased input harmonics and deterioration of other electrical performance parameters.

[0003] like Figure 1 As shown, Figure 1 This is a schematic diagram of a typical single-phase grid input PFC circuit based on a BOOST converter. Figure 2 and Figure 3 The figures show the inductor current waveforms in CCM and DCM modes, respectively. A represents the inductor current, B represents the average inductor current, and C represents the voltage Vds between the drain (D) and source (S) of the switching transistor in the BOOST converter. As can be seen from the figures, the PFC control effect is good in CCM mode. However, in DCM mode, the current waveform is discontinuous because the calculation methods for the average current are different in the two modes. Therefore, the PFC control effect is worse in DCM mode. Furthermore, under high voltage and light load conditions, operating at a fixed frequency, the inductor current operates entirely in discontinuous mode, resulting in a significant decrease in current harmonic control. It is difficult to guarantee effective current harmonic control in the DCM region using existing control methods. Summary of the Invention

[0004] The present invention aims to provide a full-load power factor correction converter and control method based on input impedance, which can achieve a natural transition between DCM mode and CCM mode.

[0005] According to a first aspect, one embodiment provides a full-load power factor correction converter based on input impedance, comprising:

[0006] AC input terminal, used to acquire single-phase AC signals;

[0007] A rectifier module is used to rectify the single-phase AC signal into a DC signal;

[0008] The boost converter module includes an inductor L1 and a switch Q1. One end of the inductor L1 is used to acquire the DC signal, and the other end of the inductor L1 is connected to the first terminal of the switch Q1. The second terminal of the switch Q1 is connected to ground. The boost converter module is used to boost the DC signal by turning the switch Q1 on and off to obtain the output voltage.

[0009] The control module is used to acquire the inductor current flowing through the inductor L1 and the output value of the voltage loop of the converter; based on the current value of the inductor current and the output value of the voltage loop of the converter, the off duty cycle of the switch Q1 in one switching cycle is determined, and then the on duty cycle of the switch Q1 in one switching cycle is obtained.

[0010] The control module is also used to obtain the proportion of time when the inductor current is greater than 0 in one switching cycle of the switching transistor Q1, and to obtain the DCM compensation coefficient.

[0011] The control module is also used to compensate the duty cycle of the switch Q1 in one switching cycle based on the DCM compensation coefficient to obtain the compensated duty cycle; acquire the PWM carrier, and generate and output a PWM control signal based on the relationship between the compensated duty cycle and the PWM carrier. The PWM control signal is used to control the switching on and off of the switch Q1.

[0012] According to a second aspect, one embodiment provides a control method for a full-load power factor correction converter based on input impedance, comprising:

[0013] Obtain the inductor current flowing through the inductor L1 and the output value of the voltage loop of the converter; based on the current value of the inductor current and the output value of the voltage loop of the converter, determine the off duty cycle of the switch Q1 in one switching cycle, and then obtain the on duty cycle of the switch Q1 in one switching cycle.

[0014] The proportion of time during which the inductor current is greater than 0 in one switching cycle of the switching transistor Q1 is obtained to obtain the DCM compensation coefficient.

[0015] The duty cycle of the switch Q1 in one switching cycle is compensated based on the DCM compensation coefficient to obtain the compensated duty cycle; the PWM carrier is obtained, and a PWM control signal is generated and output based on the relationship between the compensated duty cycle and the PWM carrier. The PWM control signal is used to control the switching on and off of the switch Q1.

[0016] According to the above embodiment of the full-load power factor correction converter based on input impedance, firstly, the off-duty cycle of the converter is calculated under the control mode based on input impedance, and then the on-duty cycle of the converter is obtained. Secondly, in DCM mode, the proportion of time when the inductor current is greater than 0 in a switching cycle is obtained to obtain the DCM compensation coefficient. Finally, the on-duty cycle is compensated based on the DCM compensation coefficient. Based on the relationship between the compensated on-duty cycle and the PWM carrier, a PWM control signal is generated and output to realize the natural transition of the converter between DCM mode and CCM mode. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a typical single-phase power grid input power factor correction circuit based on a BOOST converter.

[0018] Figure 2 This is a waveform diagram of the inductor current operating in CCM mode.

[0019] Figure 3 This is a waveform diagram of the inductor current operating in DCM mode.

[0020] Figure 4 This is a schematic diagram of the full-load power factor correction converter based on input impedance according to an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the control principle of a converter based on input impedance.

[0022] Figure 6 A waveform diagram showing the conduction duty cycle Don and the PWM carrier wave;

[0023] Figure 7 This is a schematic diagram of inductor current and switching cycle in CRM mode;

[0024] Figure 8 This is a schematic diagram of inductor current and switching cycle in DCM mode;

[0025] Figure 9 A control block diagram implemented by the control module;

[0026] Figure 10 A schematic diagram illustrating the control effect of a power factor correction converter without introducing a DCM compensation coefficient;

[0027] Figure 11 A schematic diagram illustrating the control effect of a power factor correction converter after introducing the DCM compensation coefficient;

[0028] Figure 12 A schematic diagram illustrating the control effect before and after introducing the DCM compensation coefficient under DCM mode operating conditions;

[0029] Figure 13 A schematic diagram illustrating the control effect before and after introducing the DCM compensation coefficient under mixed operating conditions of DCM and CCM modes;

[0030] Figure 14 A schematic diagram illustrating the control effect before and after introducing the DCM compensation coefficient under CCM mode operating conditions;

[0031] Figure 15 A flowchart illustrating the control method for a full-load power factor correction converter based on input impedance, provided in an embodiment of the present invention. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0033] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0034] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0035] In this embodiment of the invention, in DCM mode, the proportion of time corresponding to the inductor current being greater than 0 in a switching cycle is obtained to obtain the DCM compensation coefficient. Based on the DCM compensation coefficient, the conduction duty cycle of the switching transistor Q1 in a switching cycle is compensated, which solves the problems of large input current harmonic distortion, low power factor, and low operating efficiency under high voltage input and light load conditions. At the same time, it can naturally transition to CCM mode operation under medium and high load conditions, achieving the advantages of low input current harmonic distortion, high power factor, and low inductor current ripple current, and is suitable for the application of single-phase power factor correction converters from 150W to 3KW.

[0036] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a hybrid-mode single-phase power factor correction converter according to one embodiment, hereinafter referred to as the converter. The converter includes: an AC input terminal V_ac, a rectifier module 101, a boost converter module 102, a control module 103, and a load Rload. The AC input terminal V_ac is connected to the input terminal of the rectifier module 101, the output terminal of the rectifier module 101 is connected to the input terminal of the boost converter module 102, and the output terminal of the boost converter module 102 is connected to the load Rload. The following is a detailed description of each module.

[0037] The AC input terminal V_ac is used to acquire single-phase AC signals.

[0038] The rectifier module 101 is used to rectify a single-phase AC signal into a DC signal. For example... Figure 4 As shown, the rectifier module 101 can be a rectifier bridge circuit composed of diodes D1, D2, D3 and D4. In other embodiments, the rectifier module 101 can also use any existing rectifier circuit, which will not be described in detail here.

[0039] The boost converter module 102 includes an inductor L1 and a switch Q1. The switch Q1 includes a first terminal, a second terminal, and a control terminal. One end of the inductor L1 is used to acquire the DC signal, and the other end of the inductor L1 is connected to the first terminal of the switch Q1. The second terminal of the switch Q1 is connected to ground, and the control terminal of the switch Q1 is connected to the output terminal of the control module 103. The boost converter module 102 is used to boost the DC signal by turning the switch Q1 on and off to obtain an output voltage. In this embodiment, the boost converter module 102 can be a BOOST converter circuit, wherein the inductor current iL on the inductor L1 can be sampled by the current sampler A to obtain the sampled inductor current iL_sen, and the output voltage output by the boost converter module 102 can be sampled by the voltage sampler V to obtain the sampled output voltage Vo_sen.

[0040] Control module 103 is used to acquire the inductor current flowing through inductor L1 and the output value of the converter's voltage loop; based on the inductor current value and the converter's voltage loop output value, it determines the turn-off duty cycle of switch Q1 in one switching cycle, and then obtains the on-duty cycle of switch Q1 in one switching cycle. It should be noted that the control method described above, which determines the turn-off duty cycle of switch Q1 in one switching cycle based on the inductor current value and the converter's voltage loop output value, is a converter control method based on input impedance. Its control principle is as follows: Figure 5 As shown, the off-time duty cycle Doff of the BOOST converter is calculated using Doff = iLavg / Vloop. The on-time duty cycle Don is obtained by subtracting the off-time duty cycle Doff from the switching period Dmax. Then, the PWM control signal is obtained by comparing Don with the PWM carrier wave (PWMRAMP) to drive the switching transistor Q1 to achieve the power factor correction control effect. Here, iLavg is the average value of the inductor current, and vloop is the output value of the converter's voltage loop. Figure 6 The diagram shows the waveform of the conduction duty cycle Don versus the PWM carrier.

[0041] Based on the aforementioned input impedance-based control method, the control module 103 is further configured to obtain the proportion of time during which the inductor current is greater than 0 in one switching cycle of the switching transistor Q1, thereby obtaining the DCM compensation coefficient. In one embodiment, a comparator with an inductor current greater than 0 can be used to obtain the time ton+toff, and then, according to the switching cycle tsw=ton+toff+td, the value of (ton+toff) / (ton+toff+td) can be calculated through a low-pass filter to obtain the DCM compensation coefficient. Figure 7 and Figure 8 As shown, Figure 7 A schematic diagram showing the inductor current versus switching cycle in CRM mode is shown. Figure 8 A schematic diagram of inductor current and switching cycle in DCM mode is shown.

[0042] After obtaining the DCM compensation coefficient, multiplying the DCM compensation coefficient by the conduction duty cycle Don yields the final conduction duty cycle after compensation. Comparing this final conduction duty cycle with the PWM carrier wave yields the PWM control signal for controlling the switch Q1, thereby achieving multi-mode hybrid power factor correction control.

[0043] In this embodiment, the control module 103 is also used to compensate the duty cycle of the switch Q1 in one switching cycle based on the DCM compensation coefficient to obtain the compensated duty cycle; based on the relationship between the compensated duty cycle and the PWM carrier, a PWM control signal is generated and output, wherein the PWM control signal is used to control the switching on and off of the switch Q1.

[0044] Please refer to Figure 9 , Figure 9 The control logic diagram for control module 103 is shown below. Control module 103 includes: a low-pass filter LPF3, a divider, a limiter Saturation1, a comparator Comparator3, a comparator Comparator1, a comparator CC1, a low-pass filter LPF2_5K, a limiter Saturation2, a multiplier, a limiter Saturation3, a comparator Comparator2, an SR flip-flop, an integrator, and a comparator CC2.

[0045] First, let's explain the control logic of the control module 103 in generating the duty cycle Don of the switching transistor Q1 in one switching cycle.

[0046] The low-pass filter LPF3 is used to obtain the inductor current iL_sen. After low-pass filtering the inductor current iL_sen, the average value of the low-pass filtered inductor current is output.

[0047] The divider Divide is used to obtain the average value of the inductor current after low-pass filtering and the output value vloop of the converter's voltage loop. Dividing the inductor current after low-pass filtering by the output value vloop of the converter's voltage loop outputs the off duty cycle Doff of the switch Q1 in one switching cycle.

[0048] The limiter Saturation1 is used to limit the turn-off duty cycle Doff of the switching transistor Q1 in one switching cycle, so as to obtain the limited turn-off duty cycle Doff.

[0049] Comparator1 is used to obtain the cutoff duty cycle Doff after the limiting process and the maximum allowed on duty cycle Dmax of switch Q1. The cutoff duty cycle Doff after the limiting process is subtracted from the maximum allowed on duty cycle Dmax of switch Q1 to obtain the on duty cycle Don of switch Q1 in one switching cycle.

[0050] Next, the control logic of the control module 103 for calculating the DCM compensation coefficient will be explained.

[0051] The input of comparator CC2 obtains the instantaneous value of the inductor current iL.

[0052] The input of the low-pass filter LPF2_5K is connected to the output of the comparator CC2.

[0053] The input of the limiter Saturation2 is connected to the output of the low-pass filter LPF2_5K.

[0054] One input of the multiplier is connected to the output of the comparator1, and the other input of the multiplier is connected to the output of the saturation2 limiter; the output of the multiplier is used to output the DCM compensation coefficient.

[0055] Finally, the control logic for generating PWM control signals by control module 103 will be explained.

[0056] The input of the limiter Saturation3 is connected to the output of the multiplier.

[0057] One input of Comparator2 is used to obtain the PWM carrier, and the other input of Comparator2 is connected to the output of Saturation3.

[0058] The R terminal of the SR flip-flop is connected to the output of the comparator2, and the Q terminal of the SR flip-flop outputs the PWM control signal.

[0059] The integrator's input receives a frequency setting value; the comparator CC1's input is connected to the integrator's output, and the comparator CC1's output is connected to the integrator's reset terminal; when the PWM carrier value input to the integrator is greater than a preset value, the comparator CC1 outputs a high level to the integrator's reset terminal, resetting the integrator so that the PWM carrier is reset to integrate from 0; the integrator's output is used to output a PWM carrier with a peak value of the preset value.

[0060] Please refer to Figure 10 and Figure 11 , Figure 10 This diagram illustrates the control effect of a power factor correction converter without introducing a DCM compensation coefficient. Figure 10 CH1 shows the waveforms of the current (IAC) and voltage (VAC) of the AC signal input from a single-phase power grid; CH2 shows the waveform of the inductor current; CH3 shows the waveform of the PWM control signal; and CH4 shows the waveforms of the PWM carrier wave (PWMRAMP) and the conduction modulation signal corresponding to the switching transistor Q1. Figure 10 As can be seen, the current (IAC) of the AC signal input to a single-phase power grid is severely distorted when uncompensated. Figure 11This diagram illustrates the control effect of the power factor correction converter after introducing the DCM compensation coefficient. Figure 11 In the diagram, CH1 is a waveform diagram of the current (IAC) and voltage (VAC) of the AC signal input from a single-phase power grid, CH2 is a waveform diagram of the inductor current, and CH3 is a waveform diagram of the PWM control signal.

[0061] To better compare the control effects before and after introducing the DCM compensation coefficient, such as Figure 12 , Figure 12 The left side of the diagram shows the control effect without current compensation strategy in DCM mode, while the right side shows the control effect with current compensation strategy in DCM mode. CH1 is a waveform diagram of the current (IAC) and voltage (VAC) of the AC signal input from a single-phase power grid, CH2 is a waveform diagram of the inductor current, CH3 is a waveform diagram of the PWM control signal, and CH4 is a waveform diagram of the PWM carrier (PWMRAMP) and the conduction modulation signal corresponding to the switching transistor Q1.

[0062] Please refer to Figure 13 and Figure 14 , Figure 13 This is a schematic diagram illustrating the effect under a mixed operating condition of DCM and CCM modes. Figure 14 This is a schematic diagram illustrating the effect under the standalone CCM mode. Figure 13 and Figure 14 In the diagram, the left side shows the control effect with the current compensation strategy introduced, and the right side shows the control effect without the current compensation strategy introduced. CH1 is a waveform diagram of the current (IAC) and voltage (VAC) of the AC signal input from a single-phase power grid, CH2 is a waveform diagram of the inductor current, CH3 is a waveform diagram of the PWM control signal, and CH4 is a waveform diagram of the PWM carrier (PWMRAMP) and the conduction modulation signal corresponding to the switching transistor Q1.

[0063] In summary, the full-load power factor correction converter based on input impedance provided by the embodiments of the present invention achieves high power factor and low harmonic current distortion rate across the entire load range. It also focuses on optimizing the inductor current under low load in DCM mode, reducing the harmonic current distortion rate under high voltage and light load, and achieving the goal of power factor correction across the entire input and output range.

[0064] Please refer to Figure 15 The present invention also provides a control method for a full-load power factor correction converter based on input impedance, including steps 201 to 203.

[0065] Step 201: Obtain the inductor current flowing through inductor L1 and the output value of the voltage loop of the converter; based on the current value of the inductor current and the output value of the voltage loop of the converter, determine the off duty cycle of switch Q1 in one switching cycle, and then obtain the on duty cycle of switch Q1 in one switching cycle.

[0066] Step 202: Obtain the percentage of time during which the inductor current is greater than 0 in one switching cycle of the switching transistor Q1, and obtain the DCM compensation coefficient.

[0067] Step 203: Compensate the duty cycle of switch Q1 in one switching cycle based on the DCM compensation coefficient to obtain the compensated duty cycle; obtain the PWM carrier, and generate and output the PWM control signal based on the relationship between the compensated duty cycle and the PWM carrier. The PWM control signal is used to control the turn-on and turn-off of switch Q1.

[0068] It should be noted that the specific implementation methods and steps described above have been explained in detail in the above embodiments, and will not be repeated here.

[0069] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A full-load power factor correction converter based on input impedance, characterized in that, include: AC input terminal, used to acquire single-phase AC signals; A rectifier module is used to rectify the single-phase AC signal into a DC signal; The boost converter module includes an inductor L1 and a switch Q1. One end of the inductor L1 is used to acquire the DC signal, and the other end of the inductor L1 is connected to the first terminal of the switch Q1. The second terminal of the switch Q1 is connected to ground. The boost converter module is used to boost the DC signal by turning the switch Q1 on and off to obtain the output voltage. The control module is used to acquire the inductor current flowing through the inductor L1 and the output value of the voltage loop of the converter; Based on the current value of the inductor current and the output value of the voltage loop of the converter, the off duty cycle of the switch Q1 in one switching cycle is determined, and then the on duty cycle of the switch Q1 in one switching cycle is obtained. The control module is also used to obtain the proportion of time when the inductor current is greater than 0 in one switching cycle of the switching transistor Q1, and to obtain the DCM compensation coefficient. The control module is also used to compensate the conduction duty cycle of the switch Q1 in one switching cycle based on the DCM compensation coefficient, so as to obtain the compensated conduction duty cycle. A PWM carrier is acquired, and a PWM control signal is generated and output based on the relationship between the compensated duty cycle and the PWM carrier. The PWM control signal is used to control the on and off of the switching transistor Q1.

2. The full-load power factor correction converter based on input impedance as described in claim 1, characterized in that, The determination of the turn-off duty cycle of the switch Q1 in one switching cycle based on the current value of the inductor current and the output value of the voltage loop of the converter includes: The ratio of the inductor current value to the output value of the converter's voltage loop is used as the turn-off duty cycle of the switch Q1 in one switching cycle, wherein the turn-off duty cycle satisfies a value greater than 0 and less than 1.

3. The full-load power factor correction converter based on input impedance as described in claim 1, characterized in that, The DCM compensation coefficient compensates for the duty cycle of the switching transistor Q1 in one switching cycle, and the compensated duty cycle includes: The DCM compensation coefficient is multiplied by the duty cycle of the switch Q1 in one switching cycle to obtain the compensated duty cycle.

4. The full-load power factor correction converter based on input impedance as described in claim 1, characterized in that, The control module includes: a low-pass filter LPF3, a divider Divide, a limiter Saturation1, and a comparator Comparator1; The low-pass filter LPF3 is used to obtain the inductor current iL_sen, and after low-pass filtering the inductor current iL_sen, the average value of the low-pass filtered inductor current is output. The divider Divide is used to obtain the average value of the inductor current after low-pass filtering and the output value vloop of the voltage loop of the converter. The inductor current after low-pass filtering is divided by the output value vloop of the voltage loop of the converter to output the off duty cycle Doff of the switch Q1 in one switching cycle. The limiter Saturation1 is used to limit the turn-off duty cycle Doff of the switch Q1 in one switching cycle to obtain the limited turn-off duty cycle Doff. The comparator Comparator1 is used to obtain the cutoff duty cycle Doff after the limiting process and the maximum allowed on duty cycle Dmax of the switch Q1. The cutoff duty cycle Doff after the limiting process is subtracted from the maximum allowed on duty cycle Dmax of the switch Q1 to obtain the on duty cycle Don of the switch Q1 in one switching cycle.

5. The full-load power factor correction converter based on input impedance as described in claim 4, characterized in that, The control module also includes: a comparator CC2, a low-pass filter LPF2_5K, a limiter Saturation2, a multiplier, a limiter Saturation3, a subtractor Comparator2, and an SR flip-flop; The input terminal of the comparator CC2 obtains the instantaneous value of the inductor current iL; The input of the low-pass filter LPF2_5K is connected to the output of the comparator CC2; The input of the limiter Saturation2 is connected to the output of the low-pass filter LPF2_5K; One input of the multiplier is connected to the output of the comparator 1, and the other input of the multiplier is connected to the output of the saturation 2; the output of the multiplier is used to output the DCM compensation coefficient. The input of the limiter Saturation3 is connected to the output of the multiplier. One input of the comparator 2 is used to obtain the PWM carrier, and the other input of the subtractor 2 is connected to the output of the limiter 3. The R terminal of the SR flip-flop is connected to the output terminal of the subtractor Comparator2, and the Q terminal of the SR flip-flop outputs a PWM control signal.

6. The full-load power factor correction converter based on input impedance as described in claim 5, characterized in that, The control module also includes: an integrator and a comparator CC1; The input of the integrator acquires a frequency setting value; The input of comparator CC1 is connected to the output of integrator, and the output of comparator CC1 is connected to the reset terminal of integrator. When the value of the PWM carrier input to integrator is greater than a preset value, comparator CC1 outputs a high level to the reset terminal of integrator, and integrator is reset so that the PWM carrier is reset to integrate from 0. The output of integrator is used to output a PWM carrier with a peak value of the preset value.

7. The full-load power factor correction converter based on input impedance as described in claim 1, characterized in that, The output value of the voltage loop of the converter is the difference between the output voltage of the converter and the preset output voltage of the converter.

8. A control method for a full-load power factor correction converter based on input impedance, characterized in that, include: Obtain the inductor current flowing through inductor L1 in the converter and the output value of the voltage loop of the converter; Based on the current value of the inductor current and the output value of the voltage loop of the converter, the off duty cycle of the switch Q1 in the converter in one switching cycle is determined, and then the on duty cycle of the switch Q1 in one switching cycle is obtained. The proportion of time during which the inductor current is greater than 0 in one switching cycle of the switching transistor Q1 is obtained to obtain the DCM compensation coefficient. The duty cycle of the switch Q1 in one switching cycle is compensated based on the DCM compensation coefficient to obtain the compensated duty cycle. A PWM carrier is acquired, and a PWM control signal is generated and output based on the relationship between the compensated duty cycle and the PWM carrier. The PWM control signal is used to control the on and off of the switching transistor Q1.

9. The control method for a full-load power factor correction converter based on input impedance as described in claim 8, characterized in that, The determination of the turn-off duty cycle of the switch Q1 in one switching cycle based on the current value of the inductor current and the output value of the voltage loop of the converter includes: The ratio of the inductor current value to the output value of the converter's voltage loop is used as the turn-off duty cycle of the switch Q1 in one switching cycle, wherein the turn-off duty cycle satisfies a value greater than 0 and less than 1.

10. The control method for a full-load power factor correction converter based on input impedance as described in claim 8, characterized in that, The DCM compensation coefficient compensates for the duty cycle of the switching transistor Q1 in one switching cycle, and the compensated duty cycle includes: The DCM compensation coefficient is multiplied by the duty cycle of the switch Q1 in one switching cycle to obtain the compensated duty cycle.

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