Power factor correction circuit, control method thereof and switching power supply

Abstract

The embodiment of the invention discloses a power factor correction circuit, a control method thereof and a switching power supply, and belongs to the technical field of power electronics. The power factor correction circuit includes: an input power source; one end of the power factor correction inductor is connected with one end of the input power supply; the first end of the switch element assembly is connected with the other end of the power factor correction inductor, and the second end of the switch element assembly is connected with the other end of the input voltage; the first end of the zero voltage conversion circuit is connected with the first end of the switching element assembly and the other end of the power factor correction inductor; and one end of the output capacitor is connected with the third end of the switching element assembly and the second end of the zero voltage conversion circuit, and the other end of the output capacitor is connected with the fourth end of the switching element assembly and the third end of the zero voltage conversion circuit. The embodiment of the invention can optimize the loss of the switching device and improve the power density and the working efficiency.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of power electronics technology, and in particular to a power factor correction circuit and a control method thereof, and a switching power supply. Background Art

[0002] At present, the PFC (Power Factor Corrector) part of the communication power supply used in communication equipment widely adopts a bridgeless PFC design. However, the PFC topology in the related technology has hard switching losses of the switch tube, and as the operating frequency increases, the switching loss will become more prominent, thereby affecting the further improvement of power density and work efficiency. Summary of the invention

[0003] The main purpose of the embodiments of the present application is to provide a power factor correction circuit and a control method thereof, and a switching power supply, aiming to optimize the loss of switching devices, improve power conversion efficiency, reduce product energy consumption, and further improve power density and work efficiency.

[0004] To achieve the above object, an embodiment of the present application provides a power factor correction circuit, the power factor correction circuit comprising:

[0005] Input power;

[0006] A power factor correction inductor, one end of which is connected to one end of the input power supply;

[0007] A switch element assembly, wherein a first end of the switch element assembly is connected to the other end of the power factor correction inductor, and a second end of the switch element assembly is connected to the other end of the input voltage;

[0008] A zero voltage switching circuit, wherein a first end of the zero voltage switching circuit is connected to a first end of the switch element assembly and the other end of the power factor correction inductor;

[0009] An output capacitor, one end of which is connected to the third end of the switch element assembly and the second end of the zero voltage conversion circuit, and the other end of which is connected to the fourth end of the switch element assembly and the third end of the zero voltage conversion circuit.

[0010] In addition, to achieve the above-mentioned purpose, an embodiment of the present application further provides a control method of a power factor correction circuit, which is applied to the above-mentioned power factor correction circuit. The control method of the power factor correction circuit includes:

[0011] Controlling each switch element in the switch element assembly in the power factor correction circuit to be alternately turned on or off, so as to control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor to be consistent with the envelope phase of the input waveform of the input power supply, and controlling the power factor correction circuit to operate in a discontinuous mode and a continuous mode; wherein, in the discontinuous mode, the absolute value of the current in the power factor correction inductor drops to zero and then rises, and in the continuous mode, the absolute value of the current in the power factor correction inductor drops to a non-zero value and then rises;

[0012] The zero voltage conversion circuit is controlled to work before each switch element in the switch element assembly is turned on or off, so as to reduce the voltage of the output capacitor of the switch element assembly to zero.

[0013] The embodiment of the present application proposes a power factor correction circuit and a control method thereof, and a switching power supply, which overcomes the problem of excessive loss of switching devices in the related art. The power factor correction circuit includes: an input power supply; a power factor correction inductor, one end of which is connected to one end of the input power supply; a switch element assembly, a first end of which is connected to the other end of the power factor correction inductor, and a second end of which is connected to the other end of the input voltage; a zero voltage conversion circuit, a first end of which is connected to the first end of the switch element assembly and the other end of the power factor correction inductor; an output capacitor, one end of which is connected to the third end of the switch element assembly and the second end of the zero voltage conversion circuit, and the other end of which is connected to the fourth end of the switch element assembly and the third end of the zero voltage conversion circuit. The embodiment of the present application completes the zero voltage opening of the main switch in the switch element assembly through the zero voltage conversion circuit control, which can optimize the loss of the switching device, improve the power conversion efficiency, reduce the energy consumption of the product, and further improve the power density and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0015] Figure 1 It is a structural schematic diagram of a totem bridgeless PFC circuit in the related art;

[0016] Figure 2 A schematic diagram of the structure of a power factor correction circuit provided in an embodiment of the present application;

[0017] Figure 3 A detailed structural diagram of a power factor correction circuit provided in an embodiment of the present application;

[0018] Figure 4 A power factor correction inductor current waveform diagram of a power factor correction circuit provided in an embodiment of the present application working in a continuous mode;

[0019] Figure 5 A schematic diagram of a current trend when a power factor correction circuit provided in an embodiment of the present application operates in a continuous mode and the input power supply is in a positive half cycle;

[0020] Figure 6 Another current flow diagram when a power factor correction circuit provided in an embodiment of the present application operates in a continuous mode and the input power supply is in a positive half cycle;

[0021] Figure 7 A schematic diagram of switch drive control and inductor current waveform working cycle when a power factor correction circuit provided in this embodiment works in continuous mode and the input power is in a positive half cycle;

[0022] Figure 8 A schematic diagram of a current trend when a power factor correction circuit provided in an embodiment of the present application operates in a continuous mode and the input power supply is in a negative half cycle;

[0023] Fig. 9 Another schematic diagram of current flow when a power factor correction circuit provided in an embodiment of the present application operates in a continuous mode and the input power supply is in a negative half cycle;

[0024] Fig.10 A schematic diagram of switch drive control and inductor current waveform working cycle when a power factor correction circuit provided in this embodiment works in continuous mode and the input power is in a negative half cycle;

[0025] Fig.11 A schematic flow chart of a control method for a power factor correction circuit provided in an embodiment of the present application;

[0026] Fig.12 A schematic diagram of the structure of a switching power supply provided in an embodiment of the present application.

[0027] The realization of the purpose, functional features and advantages of the embodiments of the present application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0028] Description of Figure Numbers:

[0029]

[0030] DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of the present application.

[0032] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, in the embodiments of the present application, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In addition, the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or a scheme that satisfies both A and B.

[0034] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0035] It should also be understood that the references to "one embodiment" or "some embodiments" described in the specification of the embodiments of the present application mean that one or more embodiments of the embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Thus, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0036] In the context of dual carbon, energy conservation and emission reduction is the direction of global development. In the field of communications, with the continuous deployment of 5G communication equipment, energy consumption is also increasing. The conversion efficiency of the supporting communication power supply is an important factor in energy conservation and emission reduction in the communication field. The PFC part of the existing power supply widely adopts the bridgeless PFC design, especially the totem bridgeless PFC, which not only uses a small number of components but also has high efficiency.

[0037] The totem bridgeless PFC topology based on Si-based semiconductors cannot operate in CCM mode (Continuous Conduction Mode) due to its large reverse recovery loss, and chooses to operate in CRM mode (Critical Conduction Mode). Under this mode, the inductance is small and the ripple current is large. Compared with the CCM mode, it has no advantage in power density, and the filter design pressure at the input port is also relatively large, which also affects the improvement of power density.

[0038] The totem PFC topology based on third-generation semiconductors can operate in CCM mode because there is no large reverse recovery loss problem. However, as the operating frequency continues to increase, the proportion of hard switching losses becomes more and more obvious.

[0039] Figure 1 Schematic diagram of a totem bridgeless PFC circuit in the related art. Figure 1As shown, L1 is the inductor of the BOOST circuit, and Q1, Q2, Q3, and Q4 form the switching element assembly; Q1 and Q3 are the main PFC switching tubes, and Q2 and Q4 are synchronous rectifier tubes. Its working principle is: in the positive half cycle of the power input, Q3 is turned on, and the power supply charges and stores energy in the inductor L1 through Q3. When the current of the inductor L1 reaches the set value, Q3 is turned off, and the current of the inductor L1 is reversed. Q1 is turned on to charge the capacitor and transfer energy to the next stage. When the current of the inductor L1 drops to the set value, Q1 is turned off, and Q3 is turned on to charge the inductor L1 again and store energy, and the operation is repeated over and over again. Similarly, in the negative half cycle of the power input, Q1 is turned on, and the power supply charges and stores energy in the inductor L1 through Q1. Because Q1 and Q3 are symmetrical to each other, the working principle is consistent with the positive half cycle. This circuit is simple and efficient. But Figure 1 The main switch tubes Q1 and Q3 in the circuit are hard-on, and the switching loss is large in the continuous working mode; when Q1 and Q3 are Si (silicon) based semiconductors, the circuit can only work in CRM mode due to its large reverse recovery loss; when Q1 and Q3 are third-generation semiconductors (such as SiC (silicon carbide) / GaN (gallium nitride)), the circuit can work in CCM mode, but the hard switching loss of the switch tube still exists. At the same time, as the operating frequency increases, the switching loss will be more prominent, thus affecting the further improvement of power density and efficiency. It can be seen that the totem bridgeless PFC circuit in the relevant technology still has technical defects.

[0040] Based on this, the embodiments of the present application provide a power factor correction circuit and its control method, and a switching power supply. By designing a zero-voltage conversion circuit to assist in the control, the zero-voltage turn-on of the main switch in the switching element assembly is completed. Through appropriate control strategies, the zero-voltage turn-on of the main switch tube and the zero-current turn-off of the freewheeling tube are achieved in the positive and negative half-cycles, thereby optimizing the loss of switching devices, improving the power conversion efficiency, and reducing product energy consumption, responding to the country's call for carbon peak and carbon neutrality, creating a good living environment, and reducing the greenhouse effect; at the same time, the operating frequency can be further increased, the power density can be improved, and the performance of the third-generation semiconductors can be fully utilized.

[0041] The power factor correction circuit and control method thereof, and the switching power supply provided in the embodiments of the present application are specifically illustrated through the following embodiments. First, the power factor correction circuit in the embodiments of the present application is described.

[0042] The present application embodiment provides a power factor correction circuit, referring to Figure 2 , Figure 2 A schematic diagram of a power factor correction circuit provided in an embodiment of the present application is provided, wherein the power factor correction circuit comprises:

[0043] Input power 1;

[0044] A power factor correction inductor 2, one end of which is connected to one end of the input power supply 1;

[0045] A switch element assembly 3, wherein a first end of the switch element assembly 3 is connected to the other end of the power factor correction inductor 2, and a second end of the switch element assembly 3 is connected to the other end of the input voltage;

[0046] A zero voltage switching circuit 4, wherein a first end of the zero voltage switching circuit 4 is connected to a first end of the switch element assembly 3 and the other end of the power factor correction inductor 2;

[0047] An output capacitor 5, one end of the output capacitor 5 is connected to the third end of the switch element component 3 and the second end of the zero voltage conversion circuit 4, and the other end of the output capacitor 5 is connected to the fourth end of the switch element component 3 and the third end of the zero voltage conversion circuit 4.

[0048] It should be noted that this embodiment is an improvement based on the totem bridgeless PFC circuit in the related art. Specifically, the power factor correction circuit in this embodiment is obtained by combining the zero voltage transition (Zero voltage transition, hereinafter referred to as ZVT) circuit with the totem bridgeless PFC circuit. Based on the auxiliary design of the ZVT circuit, through appropriate control strategies, this embodiment can achieve zero voltage (ZVS, Zero voltage switch) turn-on of the main switch tube and zero current (ZCS, Zero-current switch) turn-off of the freewheeling tube in the positive and negative half cycles, optimize the loss of the switching device, improve the power conversion efficiency, and reduce the energy consumption of the product.

[0049] In some feasible embodiments, each switch element in the switch element assembly 3 is used to be alternately turned on or off to control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor 2 to be consistent with the envelope phase of the input waveform of the input power supply 1, and control the power factor correction circuit to operate in a discontinuous mode and a continuous mode;

[0050] The zero voltage conversion circuit 4 is used to operate before each switch element in the switch element assembly 3 is turned on or off to reduce the voltage drop at the common connection point of the power factor correction inductor 2, the switch element assembly 3 and the zero voltage conversion circuit 4 to zero.

[0051] It should be noted that, in this embodiment, each switch element in the switch element assembly 3 is used to alternately turn on or off, so as to control the instantaneous current of the power factor correction inductor 2, and control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor 2 to coincide with the envelope phase of the input waveform of the input power supply 1, that is, the average current of the inductor is the same as the phase of the input AC voltage. In order to reduce the conduction loss and turn-off loss of the switching device in the circuit, and also to reduce the volume of the inductor, in this embodiment, by controlling the conduction or turn-off of each switch element in the switch element assembly 3, the power factor correction circuit operates in a mixed mode. The mixed mode here can specifically include a discontinuous mode and a continuous mode. In the discontinuous mode, the absolute value of the current in the power factor correction inductor 2 drops to zero and then rises, while in the continuous mode, the absolute value of the current in the power factor correction inductor 2 drops to a non-zero value and then rises.

[0052] It should be noted that, in the present embodiment, the zero voltage conversion circuit 4 is specifically used to reduce the voltage at the common connection point of the power factor correction inductor 2, the switch element assembly 3 and the zero voltage conversion circuit 4 to zero before each switch element in the switch element assembly 3 is turned on, thereby realizing zero voltage turning on of the switch element; or, before each switch element in the switch element assembly 3 is turned off, reduce the voltage at the common connection point of the power factor correction inductor 2, the switch element assembly 3 and the zero voltage conversion circuit 4 to zero, thereby realizing zero current turning off of the switch element, thereby reducing the conduction loss and turn-off loss of the power device.

[0053] In some feasible embodiments, each switch element in the switch element assembly 3 is used to be alternately turned on or off, and when the voltage of the input power supply 1 is less than a preset voltage threshold, the power factor correction circuit is controlled to operate in a discontinuous mode.

[0054] As an example, in the power factor correction circuit provided in the present embodiment, each switching element in the switching element assembly 3 is used to be alternately turned on or off, so that when the voltage of the input power supply 1 is less than a preset voltage threshold, the power factor correction circuit is controlled to operate in a discontinuous mode; specifically, in the power factor correction circuit provided in the present embodiment, in the low voltage section of the input voltage, when the average inductance current of the power factor correction inductor 2 is small, the power factor correction circuit is controlled to operate in a discontinuous mode by controlling the conduction or shutdown of a single switching element, specifically, the average inductance current of the power factor correction inductor 2 in the power factor correction circuit is controlled to return to 0 each time and then start a new rise.

[0055] In some feasible embodiments, each switching element in the switching element assembly 3 is used to be alternately turned on or off, and when the voltage of the input power supply 1 is greater than or equal to a preset voltage threshold, the power factor correction circuit is controlled to operate in a continuous mode.

[0056] As an example, in the power factor correction circuit provided in the present embodiment, each switching element in the switching element assembly 3 is used to be alternately turned on or off, so that when the voltage of the input power supply 1 is greater than or equal to a preset voltage threshold, the power factor correction circuit is controlled to operate in a continuous mode; specifically, in the high voltage section of the input voltage, when the average inductance current of the power factor correction inductor 2 is large, the power factor correction circuit is controlled to operate in a continuous mode by controlling the conduction or shutdown of the switching element, specifically, the average inductance current of the power factor correction inductor 2 in the power factor correction circuit is controlled to start a new rise each time it does not return to 0.

[0057] This embodiment reduces the peak value of the current by controlling the circuit waveform of the average inductor current of the power factor correction inductor 2, thereby reducing the volume of the power factor correction inductor 2, reducing the circuit cost, and improving the efficiency of the power factor correction circuit. In addition, the power factor correction circuit in this embodiment adopts the same circuit topology in both the positive and negative half cycles, so that the power device is fully utilized and the circuit cost is reduced.

[0058] Combination Figure 2 and Figure 3 In some feasible embodiments, the switch element assembly 3 includes a first switch element Q1, a second switch element Q2, a third switch element Q3 and a fourth switch element Q4;

[0059] The positive electrode of the first switch element Q1 is connected to the negative electrode of the third switch element Q3, serving as the first end of the switch element assembly 3;

[0060] The positive electrode of the second switch element Q2 is connected to the negative electrode of the fourth switch element Q4, serving as the second end of the switch element assembly 3;

[0061] The cathode of the first switch element Q1 is connected to the cathode of the second switch element Q2, serving as the third end of the switch element assembly 3;

[0062] The positive electrode of the third switch element Q3 is connected to the positive electrode of the fourth switch element Q4 to serve as the fourth end of the switch element assembly 3 .

[0063] In some feasible embodiments, the zero voltage switching circuit 4 includes a resonant inductor L2, a fifth switching element Q5 and a sixth switching element Q6;

[0064] One end of the resonant inductor L2 is connected to the positive electrode of the first switching element Q1 and the negative electrode of the third switching element Q3, and the other end of the resonant inductor L2 is connected to the positive electrode of the fifth switching element Q5 and the negative electrode of the sixth switching element Q6;

[0065] The cathode of the fifth switch element Q5 is connected to one end of the output capacitor C1, the cathode of the first switch element Q1 and the cathode of the second switch element Q2;

[0066] The anode of the sixth switch element Q6 is connected to the other end of the output capacitor C1 , the anode of the third switch element Q3 , and the anode of the fourth switch element Q4 .

[0067] It is understandable that, combined with Figure 2 and Figure 3 It can be seen that Figure 2 The input power 1 corresponds to Figure 3 V in Figure 2 The power factor correction inductor 2 corresponds to Figure 3 L1 in Figure 2 The switch element assembly 3 includes Figure 3 Q1, Q2, Q3 and Q4 in Figure 2 The zero voltage switching circuit 4 includes Figure 3 L2, Q5 and Q6 in Figure 2 The output capacitor 5 corresponds to Figure 3 C1 in.

[0068] This embodiment provides a specific embodiment of a power factor correction circuit, which may include an input source V, a PFC inductor L1, a first switch element Q1, a second switch element Q2, a third switch element Q3, a fourth switch element Q4, and an output capacitor C1; the power factor correction circuit also includes a ZVT circuit, which includes a resonant inductor L2, a fifth switch element Q5, and a sixth switch element Q6; in this embodiment, the PFC inductor L1 may be arranged as follows Figure 3 The input source V shown in the figure can also be set on the other side of the input source V. The working principle is the same as Figure 3 Similar, no further description is given here. Figure 3 As shown, the switching element in this embodiment can be realized by a diode parallel switch. The switch here can be specifically a triode, a metal oxide semiconductor tube (Metal Oxide Semiconductor, hereinafter referred to as: MOS) tube, an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, hereinafter referred to as: IGBT), etc. The diode can be integrated in the device itself or added externally.

[0069] like Figure 3As shown, one end of the PFC inductor L1 is connected to the negative end of the third switch element Q3 and the positive end of the first switch element Q1 at point A, and the other end is connected to one end of the input power supply V, and the other end of the input power supply V is connected to the connection point B of the positive end of the fourth switch element Q4 and the negative end of the second switch element Q2; the positive end of the first switch element Q1 is connected to the positive end of the second switch element Q2 and to the positive end of the output capacitor C1; the negative end of the third switch element Q3 is connected to the negative end of the fourth switch element Q4 and to the negative end of the output capacitor C1. One end of the resonant inductor L2 is connected to the PFC inductor L1 at point A, and the other end is connected to the positive electrode of the fifth switch element Q5 and the negative electrode of the sixth switch element Q6 at point C. The negative electrode of the fifth switch element Q5 is connected to the positive end of the output capacitor C1, and the positive electrode of the sixth switch element Q6 is connected to the negative end of the output capacitor C1.

[0070] As an example, in this embodiment, when all the above-mentioned switching elements are Si MOS, their working mode is: the input power supply is AC, the positive and negative half-cycle working modes are symmetrical, and taking the positive half-cycle working mode of the input voltage as an example, in the positive half-cycle, the fourth switching element Q4 is in the on state, and the second switching element Q2 and the fifth switching element Q5 are in the off state.

[0071] Reference Figure 4 In some feasible embodiments, when the power factor correction circuit operates in a continuous mode, and the third switch element Q3 and the fourth switch element Q4 are turned on, and the first switch element Q1 and the second switch element Q2 are turned off, the current of the power factor correction inductor 2 increases;

[0072] When the current of the power factor correction inductor 2 rises to a first preset current value, the first switch element Q1 and the fourth switch element Q4 are turned on, the second switch element Q2 and the third switch element Q3 are turned off, the input power supply 1, the power factor correction inductor 2, the first switch element Q1, the fourth switch element Q4 and the output capacitor 5 form an inductor discharge loop, and the current of the power factor correction inductor 2 decreases;

[0073] When the current of the power factor correction inductor 2 drops to a second preset current value, the third switch element Q3 and the fourth switch element Q4 are turned on, the first switch element Q1 and the second switch element Q2 are turned off, the input power supply 1, the power factor correction inductor 2, the third switch element Q3 and the fourth switch element Q4 form an inductor charging loop, and the current of the power factor correction inductor 2 increases.

[0074] As an example, Figure 4As shown, when the power factor correction circuit works in the CCM mode, in the positive half cycle, the third switch element Q3 and the fourth switch element Q4 are first turned on by control, and the first switch element Q1 and the second switch element Q2 are turned off, the input source V, the PFC inductor L1, the third switch element Q3, and the fourth switch element Q4 form an inductor charging loop, and the current of the PFC inductor L1 increases; when the current of the PFC inductor L1 increases to the first preset current value I1, the first switch element Q1 and the fourth switch element Q4 are turned on by control, and the third switch element Q3 and the second switch element Q2 are turned off, the input source V, the PFC inductor L1, the first switch element Q1, the fourth switch element Q4 and the output capacitor C1 form an inductor discharging loop, the energy stored in the PFC inductor L1 is stored in the output capacitor C1 through the loop, and the current of the PFC inductor L1 decreases; when the current of the PFC inductor L1 decreases to the second preset current value I2, a new cycle starts to charge the PFC inductor L1, and the operation is repeated in this way. Among them, the first preset current value I1 can be set according to actual conditions. In order to make the average current waveform of the PFC inductor L1 consistent with the envelope of the input source waveform, the current of the PFC inductor L1 can be increased to a set current value each time by controlling the first switch element Q1 to the fourth switch element Q4. The current value is determined by the power supply voltage value of the input source.

[0075] Reference Figures 5 to 7 In some feasible embodiments, when the power factor correction circuit operates in a continuous mode and the AC input of the input power source 1 is in a positive half cycle, the fourth switch element Q4 is turned on, and the second switch element Q2 and the fifth switch element Q5 are turned off;

[0076] When the current of the power factor correction inductor 2 rises to the first preset current value, the first switch element Q1 is turned on, the third switch element Q3 is turned off, and the current of the power factor correction inductor 2 decreases;

[0077] When the current of the power factor correction inductor 2 drops to the second preset current, the sixth switch element Q6 is turned on, the power factor correction inductor 2 charges the resonant inductor L2 through the sixth switch element Q5, and the current of the resonant inductor L2 increases;

[0078] When the current in the resonant inductor is equal to the current in the power factor correction inductor 2, and the voltage of the output capacitor of the third switch element Q3 resonates to zero, the third switch element Q3 is turned on, the first switch element Q1 is turned off, the power factor correction inductor 2 is charged through the third switch element Q3, the current of the power factor correction inductor 2 rises, the resonant inductor is discharged through the sixth switch element Q6, and the sixth switch element Q6 is turned off before the third switch element Q3 is turned off.

[0079] As an example, Figure 5 As shown, when the PFC inductor L1 is in the freewheeling state, the power factor correction circuit is in the discharge process, the first switch element Q1 and the fourth switch element Q4 are in the on state, the third switch element Q3 is in the off state, the input source V, the first switch element Q1, the fourth switch element Q4 and the output capacitor C1 form a loop, the energy of the PFC inductor L1 is stored in the output capacitor C1, and the current of the PFC inductor L1 decreases; when the current of the PFC inductor L1 drops to the second preset current value I2, the sixth switch element Q6 starts to turn on, the input source V, the PFC inductor L1, the resonant inductor L2, the sixth switch element Q6, and the fourth switch element Q4 form a loop, and the PFC inductor L1 charges the resonant inductor L2 through the sixth switch element Q6, and the current of the resonant inductor L2 increases rapidly; when the current in the resonant inductor L2 is equal to the current in the PFC inductor L1, the output capacitor of the third switch element Q3, the output capacitor of the first switch element Q1 and the resonant capacitor L2 form a resonance, and when the voltage of the third switch element Q3 resonates to zero, the third switch element Q3 starts to turn on, realizing ZVS turn-on, and the first switch element is turned off, realizing ZCS turn-off, and the current flows as shown in Figure 6 As shown; at this time, the PFC inductor L1 is charged through the third switch element Q3, the current of the PFC inductor L1 continues to rise, the resonant inductor L2 is discharged through the sixth switch element Q6, and the sixth switch element Q6 is turned off before the third switch element Q3 is turned off; when the current of the PFC inductor L1 rises to the first preset current value I1, the third switch element Q3 is turned off, the first switch element Q1 is turned on, the PFC inductor L1 transfers energy to the subsequent stage, and the working process returns to the above Figure 4 The inductor current diagram is shown.

[0080] As an example, Figure 7 Schematic diagram of the switch drive control and the inductor current waveform working cycle in this embodiment.

[0081] As an example, when the AC input of the input source V is in the negative half cycle, the operating characteristics of the power factor correction circuit are the same as those of the AC input in the positive half cycle, that is, Figure 4In the negative half cycle, the second switch element Q2 is in the on state, and the fourth switch element Q4 and the sixth switch element Q6 are in the off state.

[0082] Reference Figures 8 to 10 In some feasible embodiments, when the power factor correction circuit operates in a continuous mode and the AC input of the input power source 1 is in a negative half cycle, the second switch element Q2 is turned on, and the fourth switch element Q4 and the sixth switch element are turned off;

[0083] When the current of the power factor correction inductor 2 rises to the second preset current value, the third switch element Q3 is turned on, the first switch element Q1 is turned off, and the current of the power factor correction inductor 2 decreases;

[0084] When the current of the power factor correction inductor 2 drops to the first preset current value, the fifth switch element Q5 is turned on, the first switch element Q1 is turned off, the power factor correction inductor 2 charges the resonant inductor through the fifth switch element Q5, and the current of the resonant inductor increases;

[0085] When the current in the resonant inductor is equal to the current in the power factor correction inductor 2, and the voltage of the output capacitor 5 of the first switching element Q1 resonates to zero, the first switching element Q1 is turned on, the third switching element Q3 is turned off, the power factor correction inductor 2 is charged through the first switching element Q1, the current of the power factor correction inductor 2 rises, the resonant inductor is discharged through the fifth switching element Q5, and the fifth switching element Q5 is turned off before the first switching element Q1 is turned off.

[0086] As an example, Figure 8As shown, when the PFC inductor L1 is in the freewheeling state, the output capacitor C1 and the load Vdc are discharging, the third switch element Q3 and the second switch element Q2 are in the on state, the first switch element Q1 is in the off state, the input source V, the second switch element Q2, the third switch element Q3 and the output capacitor C1 form a loop, the energy of the PFC inductor L1 is stored in the output capacitor C1, and the current of the PFC inductor L1 decreases; when the current of the PFC inductor L1 decreases to the first preset current value I1, the fifth switch element Q5 starts to turn on, the input source V, the PFC inductor L1, the resonant L2, the fifth switch element Q5, and the second switch element Q2 form a loop, and the PFC inductor L1 charges the resonant inductor L2 through the fifth switch element Q5, and the current of the resonant inductor L2 increases rapidly; when the current in the resonant inductor L2 is equal to the current in the PFC inductor L1, the output capacitor of the third switch element Q3, the output capacitor of the first switch element Q1 and the resonant inductor L2 form a resonance, and when the voltage of the first switch element Q1 resonates to zero, the first switch element Q1 starts to turn on, realizing ZVS turn-on, and the third switch element Q3 turns off, realizing ZCS turn-off, and the current flows as shown in Fig. 9 As shown; at this time, the PFC inductor L1 is charged through the first switch element Q1, the current of the PFC inductor L1 continues to rise, the resonant inductor L2 is discharged through the fifth switch element Q5, and the fifth switch element Q5 is turned off before the first switch element Q1 is turned off; when the current of the PFC inductor L1 rises to the second preset current value I2, the first switch element Q1 is turned off, the third switch element Q3 is turned on, and the PFC inductor L1 transfers energy to the subsequent stage.

[0087] As an example, Fig.10 Schematic diagram of the switch drive control and the inductor current waveform working cycle in this embodiment.

[0088] In some feasible embodiments, when the power factor correction circuit operates in a discontinuous mode, the fifth switch element Q5 and the sixth switch element Q6 are turned off during the entire AC cycle.

[0089] In this embodiment, when the power factor correction circuit operates in a discontinuous mode (such as a critical conduction mode and a light load mode), the zero voltage conversion circuit 4 does not work, the current of the PFC inductor L1 drops to zero, and the power factor correction circuit realizes ZVS opening through current zero crossing detection. At this time, the working characteristics of the power factor correction circuit can also refer to Figure 4 The corresponding embodiments.

[0090] This embodiment provides a power factor correction circuit, which can solve the problem of large switching tube loss when the totem bridgeless PFC circuit based on silicon-based semiconductor design of the power supply works in CCM mode; on the other hand, it can also solve the problem of large switching loss when the totem bridgeless PFC circuit based on third-generation semiconductor design works in high switching frequency, further increase the switching frequency, and improve the power density.

[0091] In addition, the present application also provides a control method for a power factor correction circuit, referring to Fig.11 , the control method of the power factor correction circuit includes:

[0092] Step S10, controlling each switch element in the switch element assembly in the power factor correction circuit to be alternately turned on or off, so as to control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor to be consistent with the envelope phase of the input waveform of the input power supply, and controlling the power factor correction circuit to operate in a discontinuous mode and a continuous mode; wherein, in the discontinuous mode, the absolute value of the current in the power factor correction inductor drops to zero and then rises, and in the continuous mode, the absolute value of the current in the power factor correction inductor drops to a non-zero value and then rises;

[0093] Step S20, controlling the zero voltage conversion circuit to operate before each switch element in the switch element assembly is turned on or off, so as to reduce the voltage of the output capacitor of the switch element assembly to zero.

[0094] The control method of the power factor correction circuit proposed in this embodiment can be applied to the power factor correction circuit proposed in the above embodiments, and belongs to the same inventive concept as the power factor correction circuit proposed in the above embodiments. The technical details not fully described in this embodiment can be referred to any of the above embodiments, and this embodiment has the same beneficial effects as the above embodiments of the power factor correction circuit.

[0095] In addition, the present application also provides a switching power supply, referring to Fig.12 The switching power supply includes: a power factor correction circuit 01 and a control unit 02, the control unit 02 includes a processor 021 and a control program 022, and when the control program 022 is executed by the processor 021, the control method of the power factor correction circuit provided in the above embodiment is implemented.

[0096] It can be understood that the power factor correction circuit 01 can be the power factor correction circuit provided by any of the above embodiments.

[0097] Those skilled in the art will understand that Fig.12The structure shown in the figure does not constitute a limitation on the switching power supply, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0098] The switching power supply proposed in this embodiment and the power factor correction circuit proposed in the above embodiments belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to any of the above embodiments, and this embodiment has the same beneficial effects as the above embodiments of the power factor correction circuit.

[0099] It should be noted that the technical solutions of the various embodiments of the embodiments of the present application can be combined with each other, but it must be based on the fact that it can be implemented by technical personnel in this field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the embodiments of the present application.

[0100] The above are only preferred embodiments of the embodiments of the present application, and are not intended to limit the patent scope of the embodiments of the present application. Any equivalent structure or equivalent process transformation made using the description and drawings of the embodiments of the present application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the embodiments of the present application.

Claims

1. A power factor correction circuit, characterized in that: The power factor correction circuit comprises: Input power; A power factor correction inductor, one end of which is connected to one end of the input power supply; A switch element assembly, wherein a first end of the switch element assembly is connected to the other end of the power factor correction inductor, and a second end of the switch element assembly is connected to the other end of the input voltage; A zero voltage switching circuit, wherein a first end of the zero voltage switching circuit is connected to a first end of the switch element assembly and the other end of the power factor correction inductor; An output capacitor, one end of which is connected to the third end of the switch element assembly and the second end of the zero voltage conversion circuit, and the other end of which is connected to the fourth end of the switch element assembly and the third end of the zero voltage conversion circuit.

2. The power factor correction circuit according to claim 1, characterized in that: Each switch element in the switch element assembly is used to be alternately turned on or off to control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor to be consistent with the envelope phase of the input waveform of the input power supply, and control the power factor correction circuit to operate in a discontinuous mode and a continuous mode; The zero voltage conversion circuit is used to work before each switch element in the switch element assembly is turned on or off to reduce the voltage drop at the common connection point of the power factor correction inductor, the switch element assembly and the zero voltage conversion circuit to zero.

3. The power factor correction circuit according to claim 1, characterized in that: The switch element assembly includes a first switch element, a second switch element, a third switch element and a fourth switch element; The positive electrode of the first switch element is connected to the negative electrode of the third switch element, serving as the first end of the switch element assembly; The positive electrode of the second switch element is connected to the negative electrode of the fourth switch element, serving as the second end of the switch element assembly; The cathode of the first switch element is connected to the cathode of the second switch element, serving as the third terminal of the switch element assembly; The positive electrode of the third switch element is connected to the positive electrode of the fourth switch element as the fourth end of the switch element assembly.

4. The power factor correction circuit according to claim 3, characterized in that: When the power factor correction circuit operates in a continuous mode, and the third switch element and the fourth switch element are turned on, and the first switch element and the second switch element are turned off, the current of the power factor correction inductor increases; When the current of the power factor correction inductor rises to a first preset current value, the first switch element and the fourth switch element are turned on, the second switch element and the third switch element are turned off, the input power supply, the power factor correction inductor, the first switch element, the fourth switch element and the output capacitor form an inductor discharge loop, and the current of the power factor correction inductor decreases; When the current of the power factor correction inductor drops to a second preset current value, the third switch element and the fourth switch element are turned on, the first switch element and the second switch element are turned off, the input power supply, the power factor correction inductor, the third switch element and the fourth switch element form an inductor charging loop, and the current of the power factor correction inductor increases.

5. The power factor correction circuit according to claim 4, characterized in that: The zero voltage switching circuit includes a resonant inductor, a fifth switching element and a sixth switching element; One end of the resonant inductor is connected to the positive electrode of the first switching element and the negative electrode of the third switching element, and the other end of the resonant inductor is connected to the positive electrode of the fifth switching element and the negative electrode of the sixth switching element; The cathode of the fifth switch element is connected to one end of the output capacitor, the cathode of the first switch element and the cathode of the second switch element; The anode of the sixth switch element is connected to the other end of the output capacitor, the anode of the third switch element, and the anode of the fourth switch element.

6. The power factor correction circuit according to claim 5, characterized in that: When the power factor correction circuit operates in a continuous mode and the AC input of the input power source is in a positive half cycle, the fourth switch element is turned on, and the second switch element and the fifth switch element are turned off; When the current of the power factor correction inductor rises to the first preset current value, the first switch element is turned on, the third switch element is turned off, and the current of the power factor correction inductor decreases; When the current of the power factor correction inductor drops to the second preset current, the sixth switch element is turned on, the power factor correction inductor charges the resonant inductor through the sixth switch element, and the current of the resonant inductor increases; When the current in the resonant inductor is equal to the current in the power factor correction inductor and the voltage of the output capacitor of the third switching element resonates to zero, the third switching element is turned on, the first switching element is turned off, the power factor correction inductor is charged through the third switching element, the current of the power factor correction inductor increases, the resonant inductor is discharged through the sixth switching element, and the sixth switching element is turned off before the third switching element is turned off.

7. The power factor correction circuit according to claim 5, characterized in that: When the power factor correction circuit operates in a continuous mode and the AC input of the input power source is in a negative half cycle, the second switch element is turned on, and the fourth switch element and the sixth switch element are turned off; When the current of the power factor correction inductor rises to the second preset current value, the third switch element is turned on, the first switch element is turned off, and the current of the power factor correction inductor decreases; When the current of the power factor correction inductor drops to the first preset current value, the fifth switch element is turned on, the first switch element is turned off, the power factor correction inductor charges the resonant inductor through the fifth switch element, and the current of the resonant inductor increases; When the current in the resonant inductor is equal to the current in the power factor correction inductor and the voltage of the output capacitor of the first switching element resonates to zero, the first switching element is turned on, the third switching element is turned off, the power factor correction inductor is charged through the first switching element, the current of the power factor correction inductor increases, the resonant inductor is discharged through the fifth switching element, and the fifth switching element is turned off before the first switching element is turned off.

8. The power factor correction circuit according to claim 5, characterized in that: When the power factor correction circuit operates in the discontinuous mode, the fifth switching element and the sixth switching element are turned off during the entire AC cycle.

9. A control method for a power factor correction circuit, characterized in that: The control method of the power factor correction circuit includes: Controlling each switch element in the switch element assembly in the power factor correction circuit to be alternately turned on or off, so as to control the envelope phase of the current waveform of the instantaneous current of the power factor correction inductor to be consistent with the envelope phase of the input waveform of the input power supply, and controlling the power factor correction circuit to operate in a discontinuous mode and a continuous mode; wherein, in the discontinuous mode, the absolute value of the current in the power factor correction inductor drops to zero and then rises, and in the continuous mode, the absolute value of the current in the power factor correction inductor drops to a non-zero value and then rises; The zero voltage conversion circuit is controlled to operate before each switch element in the switch element assembly is turned on or off, so as to reduce the voltage drop at the common connection point of the power factor correction inductor, the switch element assembly and the zero voltage conversion circuit to zero.

10. A switching power supply, characterized in that: The switching power supply comprises: a power factor correction circuit and a control unit, the control unit comprises a processor and a control program, and the control program implements the control method of the power factor correction circuit as claimed in claim 9 when executed by the processor.

Images