A bridgeless power factor improvement circuit and system

Abstract

The utility model provides a kind of bridgeless power factor improvement circuit and system, it is related to power electronics technical field, the bridgeless power factor improvement circuit includes ac power supply module, switching module, first capacitor module, switching control module;Switching module at least includes first main switch tube, second main switch tube;First capacitor module includes first energy storage capacitor, second energy storage capacitor.For any ac input cycle, bridgeless power factor improvement circuit includes two kinds of working conditions, and for any working condition, switching control module, for adjusting the on-off state of main switch tube under current working condition, for corresponding energy storage capacitor power supply.Equivalent to half of preset output voltage, wherein voltage value is same between energy storage capacitor under each working condition, to reduce the input current flowing through corresponding main switch tube.Based on this, the present application can reduce switch tube loss on the basis of improving input power factor, improve boost efficiency.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and more specifically, to a bridgeless power factor improvement circuit and system. Background Technology

[0002] The basic circuit structure of most electrical products is composed of power semiconductors such as frequency converters. To comply with electromagnetic compatibility standards, power factor correction circuits are also included to optimize current waveform distortion and phase differences caused by AC-DC conversion in the basic circuit structure. To reduce switching losses while improving the input power factor, engineers typically prefer bridgeless power factor correction circuits.

[0003] However, since the bridgeless power factor improvement circuit lacks a bridge diode and relies on only one switching transistor to achieve power supply boost regulation, its boost efficiency is low.

[0004] Therefore, there is an urgent need for a bridgeless power factor improvement circuit that can improve the input power factor, reduce switching losses, and improve boost efficiency. Utility Model Content

[0005] The purpose of this invention is to provide a bridgeless power factor improvement circuit and system that can reduce switching losses and improve boost efficiency while improving the input power factor.

[0006] In a first aspect, this application provides a bridgeless power factor improvement circuit, which includes: an AC power supply module, a switching module, a first capacitor module, and a switching control module; the switching module includes at least a first main switching transistor and a second main switching transistor; the first capacitor module includes a first energy storage capacitor and a second energy storage capacitor; The switch control module is connected to the control terminals of the first main switch transistor and the second main switch transistor; the first terminal of the AC power supply module is connected to the first terminal of the first energy storage capacitor and the first terminal of the first main switch transistor; the second terminal of the AC power supply module is connected to the first terminal of the second main switch transistor, the second terminal of the first energy storage capacitor, and the first terminal of the second energy storage capacitor; the second terminal of the second energy storage capacitor, the second terminal of the first main switch transistor, and the second terminal of the second main switch transistor are all grounded. For any AC input cycle, the bridgeless power factor improvement circuit includes two operating states. For any operating state, the switch control module is used to adjust the on / off state of the main switch in the current operating state to supply power to the corresponding energy storage capacitor. In each operating state, the voltage values ​​between the energy storage capacitors are the same and equal to half of the preset output voltage, so as to reduce the input current flowing through the corresponding main switch.

[0007] Optionally, the bridgeless power factor improvement circuit further includes a second capacitor module, which includes a plurality of electrolytic capacitors connected in parallel; the first terminal of the plurality of electrolytic capacitors connected in parallel is connected to the first terminal of the first energy storage capacitor; and the second terminal of the plurality of electrolytic capacitors connected in parallel is grounded. In this system, the capacitance values ​​of each electrolytic capacitor are the same and equal to the total capacitance value of the first capacitor module.

[0008] Optionally, the capacitance value of the first energy storage capacitor and / or the second energy storage capacitor is equal to twice the capacitance value between each electrolytic capacitor.

[0009] Optionally, the switching module further includes an auxiliary switching transistor, the first end of which is connected to the first end of the second main switching transistor; the second end of the auxiliary switching transistor is connected to the second end of the first energy storage capacitor and the first end of the second energy storage capacitor; the switching control module is also connected to the control terminal of the auxiliary switching transistor.

[0010] Optionally, when the first operating state is in the positive half-cycle of the AC input, the first operating state includes a first discharge mode; When in the first discharge mode, both the first and second main switches are off, while the auxiliary switch is on.

[0011] Optionally, when the second operating state is in the negative half-cycle of the AC input, the second operating state includes a second discharge mode; When in the second discharge mode, the first main switch, the second main switch, and the auxiliary switch are all turned off.

[0012] Optionally, when the AC power supply module includes an AC power supply unit and an energy storage inductor, the positive terminal of the AC power supply unit is connected to the first terminal of the energy storage inductor, the second terminal of the energy storage inductor is connected to the first terminal of the first energy storage capacitor, and the negative terminal of the AC power supply unit is connected to the first terminal of the second main switch.

[0013] Optionally, when the first operating state is in the positive half-cycle of the AC input, the first operating state also includes a first charging mode; In the first charging mode, the first main switch is turned on, while the auxiliary switch and the second main switch are turned off.

[0014] Optionally, when the second operating state is in the negative half-cycle of the AC input, the second operating state also includes a second charging mode; In the second charging mode, both the first main switch and the auxiliary switch are turned off, while the second main switch is turned on.

[0015] Secondly, the present invention also provides a bridgeless power factor improvement system, which includes the bridgeless power factor improvement circuit of any one of the first aspects described above.

[0016] The bridgeless power factor improvement circuit and system provided by this utility model have the following beneficial effects: The bridgeless power factor improvement circuit in this application includes an AC power supply module, a switching module, a first capacitor module, and a switching control module. The switching module includes at least a first main switch and a second main switch. The first capacitor module includes a first energy storage capacitor and a second energy storage capacitor. For any AC input cycle, the bridgeless power factor improvement circuit includes two operating states. For any operating state, the switching control module is used to adjust the on / off state of the main switch in the current operating state to supply power to the corresponding energy storage capacitor. The voltage values ​​of the energy storage capacitors are the same across all operating states and are equal to half of the preset output voltage, thereby reducing the input current flowing through the corresponding main switch. Based on this, this application, while improving the input power factor, can adjust the on / off state of the corresponding main switch in each operating state through the switching control module to supply power to the corresponding energy storage capacitor, making its capacitance value numerically equal to half of the preset output voltage. This reduces the input current flowing through the corresponding main switch, thereby reducing switch losses and improving boost efficiency. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 One of the structural schematic diagrams of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 2 A second schematic diagram of the structure of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 3 The third schematic diagram of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 4 A schematic diagram of the switching waveforms of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 5 A schematic diagram of the first mode of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 6 This is a schematic diagram of the second mode of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 7 Fourth schematic diagram of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 8A schematic diagram of the third mode of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 9 A schematic diagram of the fourth mode of the bridgeless power factor improvement circuit provided in the embodiments of this application; Figure 10 This is a waveform diagram of a conventional bridgeless power factor improvement circuit in the prior art; Figure 11 This is a waveform diagram of the bridgeless power factor improvement circuit in the embodiment of this application.

[0019] Icons: 10 - Bridgeless power factor improvement circuit; 101 - AC power supply module; 102 - Switching module; 103 - First capacitor module; 104 - Switching control module; 105 - Second capacitor module; 201 - AC power supply unit; SW1 - First main switch transistor; SW2 - Second main switch transistor; SW3 - Auxiliary switch transistor; C1 - First energy storage capacitor; C2 - Second energy storage capacitor; L1 - Energy storage inductor; D1 - Diode. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0024] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0025] As described in the prior art, in a conventional bridgeless power factor improvement circuit, the input current of the energy storage capacitor is sinusoidal in any half-cycle of AC input by relying solely on the on / off state of a single switch. For example, when the switch is on, the boost coil of the bridgeless power factor improvement circuit calculates the magnetic energy based on the input current. Then, when the switch is off, the magnetic energy of the boost coil is output to the electrolytic capacitor to power it. Since the boost of the conventional bridgeless power factor improvement circuit is achieved by only one switch, the boost efficiency will be greatly reduced.

[0026] Therefore, this embodiment provides a new bridgeless power factor improvement circuit to overcome the aforementioned problem of low boost efficiency.

[0027] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Please refer to Figure 1 , Figure 1 The diagram shows the structure of the bridgeless power factor improvement circuit 10 in this embodiment. The bridgeless power factor improvement circuit 10 includes an AC power supply module 101, a switching module 102, a first capacitor module 103, and a switching control module 104. The switching module 102 includes at least a first main switch SW1 and a second main switch SW2. The first capacitor module 103 includes a first energy storage capacitor C1 and a second energy storage capacitor C2. In this embodiment, the switch control module 104 is connected to the control terminal of the first main switch SW1 and the control terminal of the second main switch SW2; the first terminal of the AC power supply module 101 is connected to the first terminal of the first energy storage capacitor C1 and the first terminal of the first main switch SW1; the second terminal of the AC power supply module 101 is connected to the first terminal of the second main switch SW2, the second terminal of the first energy storage capacitor C1, and the first terminal of the second energy storage capacitor C2; the second terminal of the second energy storage capacitor C2, the second terminal of the first main switch SW1, and the second terminal of the second main switch SW2 are all grounded.

[0029] For any AC input cycle, the bridgeless power factor improvement circuit in this embodiment includes two operating states. For any operating state, the switch control module is used to adjust the on / off state of the main switch in the current operating state to supply power to the corresponding energy storage capacitor.

[0030] In each operating state, the voltage values ​​between the energy storage capacitors are the same and equal to half of the preset output voltage, so as to reduce the input current flowing through the corresponding main switch.

[0031] In this embodiment, the first energy storage capacitor and the second energy storage capacitor are equivalent to voltage doublers, and their corresponding voltage values ​​are both half of the preset output voltage. Based on this, the output voltage of the bridgeless power factor improvement circuit is equal to the preset output voltage, thereby achieving the voltage boosting purpose of the bridgeless power factor improvement circuit.

[0032] In this embodiment, the switching control module adjusts the on / off state of the corresponding main switch in each working state to supply power to the corresponding energy storage capacitor, so that the capacitance value is equal to half of the preset output voltage. In this way, by reducing the input current flowing through the corresponding main switch, the input power factor is improved, thereby reducing the switching transistor loss and improving the boost efficiency.

[0033] To further enhance the adaptability of the bridgeless power factor correction circuit and achieve output voltage boost settings, please refer to... Figure 2 , Figure 2 This diagram illustrates another structural schematic of the bridgeless power factor improvement circuit in this embodiment. The bridgeless power factor improvement circuit 10 further includes a second capacitor module 105, which comprises multiple electrolytic capacitors connected in parallel. The first terminals of the multiple parallel electrolytic capacitors are connected to the first terminal of the first energy storage capacitor C1. The second terminals of the multiple parallel electrolytic capacitors are grounded. All electrolytic capacitors have the same capacitance value.

[0034] Assuming the bridgeless power factor improvement circuit in this embodiment includes n capacitors, excluding the first energy storage capacitor C1 and the second energy storage capacitor C2, a total of n-2 electrolytic capacitors are provided under the second capacitor module 105, which can be represented as the first electrolytic capacitor C3, the second electrolytic capacitor C4, ..., the (n-2)th electrolytic capacitor Cn; the capacitance value of each electrolytic capacitor can then be expressed as: For ease of description, it can be assumed that the capacitance value of each electrolytic capacitor in the second capacitor module 105 is... .

[0035] This embodiment also provides a method for calculating the optimal electrolytic capacitance among the electrolytic capacitors, which can be expressed as: ;In the formula, The total electrostatic capacitance (any fixed value); The total number of individual capacitors in a bridgeless power factor improvement circuit.

[0036] It should be noted that, in order to ensure that the output voltage is doubled in this embodiment, the first energy storage capacitor C1, the second energy storage capacitor C2, and the electrolytic capacitors under the second capacitor module 105 need to maintain static capacitance balance.

[0037] Based on this, the capacitance of each electrolytic capacitor connected in parallel must be the same as the combined capacitance of the first energy storage capacitor C1 and the second energy storage capacitor C2 connected in series. That is, the capacitance values ​​of each electrolytic capacitor are the same and are all equal to the total capacitance value of the first capacitor module 103.

[0038] After satisfying the above two conditions, the first electrolytic capacitor, the second electrolytic capacitor, ..., the (n-2)th electrolytic capacitor can be regarded as individual capacitors, and the first energy storage capacitor C1 and the second energy storage capacitor C2 can be regarded as two corresponding individual capacitors. At this time, the optimal capacitance can be expressed as: =

[0039] =

[0040] = = .

[0041] Based on this, it can be deduced from the above formula that the capacitance value of the first energy storage capacitor C1 and / or the second energy storage capacitor C2 in this embodiment is equal to twice the capacitance value between each electrolytic capacitor, and the corresponding expression satisfies: .

[0042] This embodiment also provides an example of the optimal capacitance of an electrolytic capacitor, wherein, assuming a comprehensive capacitance... The capacitance value is 1000μF. The total number of electrolytic capacitors and the optimal capacitance value of each electrolytic capacitor can be seen in Table 1.

[0043] Table 1

[0044] Wherein, Quantity is the total number of capacitors in the bridgeless power factor improvement circuit (including energy storage capacitors and each electrolytic capacitor), Capacitance is the optimal capacitance of the first energy storage capacitor C1, the second energy storage capacitor C2, the first electrolytic capacitor C3, ..., the (x-2)th electrolytic capacitor Cx; Symbol is the name of each capacitor; Combined Capacity is the combined capacitance corresponding to the output voltage Vdc of the bridgeless power factor improvement circuit in this embodiment.

[0045] It can be seen that in this embodiment, when there are parallel electrolytic capacitors and the number of parallel electrolytic capacitors is greater, the combined capacitance corresponding to the output voltage Vdc of the bridgeless power factor improvement circuit is greater.

[0046] In this embodiment, the switch control module can send different control signals to the main switch transistor under different operating states to assist in the switching of the first switch transistor and to power the first energy storage capacitor. Please refer to [reference needed]. Figure 3 , Figure 3 This diagram shows another structural schematic of the bridgeless power factor improvement circuit in this embodiment; the switching module 102 in this embodiment also includes an auxiliary switching transistor SW3, the first end of which is connected to the first end of the second main switching transistor SW2; the second end of the auxiliary switching transistor SW3 is connected to the second end of the first energy storage capacitor C1 and the first end of the second energy storage capacitor C2; the switching control module 104 is also connected to the control terminal of the auxiliary switching transistor SW3.

[0047] In the first operating state, the switch control module 104 is used to send a pair of complementary signals to the auxiliary switch SW3 and the first main switch SW1 respectively to supply power to the first energy storage capacitor C1.

[0048] In the second operating state, the switch control module 104 is used to send a pair of complementary signals to the second main switch SW2 at a preset time interval to supply power to the second energy storage capacitor C2.

[0049] It should be noted that the pair of complementary signals described in this embodiment can be signal commands including high-level signals and low-level signals. Unless explicitly stated that a preset time interval needs to be set, they are all meant to be sent simultaneously.

[0050] Based on this, in the first working state, the signal transmission mode of the switch control module 104 can be understood as follows: at the same time, the switch control module 104 sends a high level to the auxiliary switch SW3 and a low level to the first main switch SW1; or at the same time, the switch control module 104 sends a low level to the auxiliary switch SW3 and a high level to the first main switch SW1.

[0051] Similarly, assuming the preset time interval is Δt, the preset time interval Δt can be calculated as: Δt = t1 - t0, where t1 is the first moment; t0 is the initial moment, where the first moment t1 lags behind the initial moment t0 on the time scale.

[0052] At this time, in the second operating state, the signal transmission method of the switch control module 104 can be understood as follows: The switch control module 104 can send a high level to the second main switch SW2 at an initial time t0, and then send a low level to the second main switch SW2 again at the first time t1 after a preset time interval Δt. Alternatively, the switch control module 104 can send a low level to the second main switch SW2 at an initial time t0, and then send a high level to the second main switch SW2 again at the first time t1 after a preset time interval Δt, thereby achieving the purpose of switching the on / off state of the second main switch SW2.

[0053] Please refer to Figure 4 , Figure 4 The diagram shows the switching waveform of the bridgeless power factor improvement circuit in this embodiment. For any AC input cycle, this embodiment can divide the operating state of the bridgeless power factor improvement circuit according to one AC input half-cycle. For example, when it is in the positive half-cycle of the AC input, that is, when the input voltage is V... L Currently, the bridgeless power factor correction circuit is in its first operating state. When it is in the negative half-cycle of the AC input, i.e., the input voltage is V... N The current state of the bridgeless power factor improvement circuit is in its second operating state.

[0054] in, Figure 4 The example also demonstrates the switching relationship between the main and auxiliary switches in the first working state. It should be noted that this embodiment does not limit the duty cycle of the switches, as long as the current can be stored in the energy storage inductor in a sinusoidal manner. When in the negative half-cycle of AC input, i.e., the input voltage is V N The current state of the bridgeless power factor improvement circuit is in its second operating state.

[0055] Based on this, if it is assumed that the AC power supply module directly discharges to supply power to the first energy storage capacitor C1 and / or the second energy storage capacitor C2, the first operating state includes at least the first discharge mode; the second operating state includes at least the second discharge mode.

[0056] Please refer to Figure 5 , Figure 5 The diagram shows the first mode of the bridgeless power factor improvement circuit in this embodiment. In this embodiment, when the first operating state is in the positive half-cycle of the AC input, in the first discharge mode, the first main switch SW1 and the second main switch SW2 are both cut off, and the auxiliary switch SW3 is turned on.

[0057] At this time, the first current I1 flows out from the first terminal of the AC power supply module 101, passes through the first energy storage inductor L1 and the auxiliary switch SW3 in sequence, and returns to the second terminal of the AC power supply module 101 to supply power to the first energy storage capacitor C1.

[0058] Please refer to Figure 6, Figure 6 The diagram shows the second mode of the bridgeless power factor improvement circuit in this embodiment. In this embodiment, when the second operating state is in the negative half-cycle of the AC input, the first main switch SW1, the second main switch SW2, and the auxiliary switch are all turned off in the second discharge mode.

[0059] In this state, the second current I2 flows out from the second terminal of the AC power supply module 101, passes through the auxiliary switch SW3, the second energy storage capacitor C2, and the first main switch SW1 in sequence, and returns to the first terminal of the AC power supply module 101 to supply power to the second energy storage capacitor C2.

[0060] Please refer to Figure 7 , Figure 7 This diagram shows another structural schematic of the bridgeless power factor improvement circuit in this embodiment; the AC power supply module 101 includes an AC power supply unit 201 and an energy storage inductor L1; the positive terminal of the AC power supply unit 201 is connected to the first terminal of the energy storage inductor L1, the second terminal of the energy storage inductor L1 is connected to the first terminal of the first energy storage capacitor C1; the negative terminal of the AC power supply unit 201 is connected to the first terminal of the second main switch.

[0061] When the switch control module 104 is still in each working state, it sends corresponding control signals to the corresponding main switch transistor to charge the energy storage inductor L1, and then uses the magnetic energy of the energy storage inductor L1 to supply power to the corresponding energy storage capacitor. The first working state also includes the first charging mode; the second working state also includes the second charging mode.

[0062] Please refer to Figure 8 , Figure 8 The diagram shows the third mode of the bridgeless power factor improvement circuit in this embodiment. In the first charging mode, the first main switch SW1 is turned on, while the auxiliary switch SW3 and the second main switch SW2 are both turned off. At this time, the third current I3 flows out from the first terminal of the AC power supply unit 201, passes through the energy storage inductor L1, the first main switch SW1, and the second main switch SW2 in sequence, and returns to the negative terminal of the AC power supply unit 201 to supply power to the energy storage inductor L1.

[0063] Please refer to Figure 9 , Figure 9 The diagram shows the fourth mode of the bridgeless power factor improvement circuit in this embodiment. In the second charging mode, the first main switch SW1 and the auxiliary switch SW3 are both off, while the second main switch SW2 is on. At this time, the fourth current I4 flows out from the negative terminal of the AC power supply unit 201, passes through the second main switch SW2, the first main switch SW1, and the energy storage inductor L1 in sequence, and returns to the positive terminal of the AC power supply unit 201 to power the energy storage inductor L1.

[0064] In addition, please continue to refer to Figure 7 In this embodiment, the bridgeless power factor improvement circuit also includes a diode D1, the anode of which is connected to the first terminal of the AC power supply module 101; the cathode of which is connected to the first terminal of the first energy storage capacitor C1. In one possible implementation, the diode D1 may be a fast recovery diode D1.

[0065] Please continue to refer to this. Figure 7 Taking the first working state as an example, the principle of the charging / discharging state of the bridgeless power factor improvement circuit is explained.

[0066] In the first charging mode, the first main switch SW1 is turned on, while the auxiliary switch SW3 and the second main switch SW2 are all turned off. In this mode, after the first main switch SW1 is turned on, magnetic energy can be stored in the energy storage inductor L1, and the corresponding charge can be expressed as: ; In the formula, Q is the charge (unit: coulomb), C is the capacitance (unit: farad), and V is the voltage (unit: volt). i Input current (unit: amperes).

[0067] Then it enters the first discharge mode. At this time, the first main switch SW1 and the second main switch SW2 are both cut off, and the auxiliary switch SW3 is turned on. The energy storage inductor L1 discharges to supply power to the first energy storage capacitor C1. The corresponding voltage of the first energy storage capacitor is... It can be represented as: ; In the formula, This is the discharge current.

[0068] Similarly, the calculation process described above can be referenced for the second working state. It will not be repeated here.

[0069] This embodiment also provides a comparative experiment on input current.

[0070] Assuming comprehensive electrostatic capacity The voltage is 1000μF, and the load is 100Ω. Please refer to [the relevant documentation]. Figure 10 , Figure 11 , Figure 10 This is a waveform diagram of a conventional bridgeless power factor correction circuit in the prior art. Figure 11 The waveform diagram of the bridgeless power factor improvement circuit provided in this embodiment shows that the input current of a conventional bridgeless power factor improvement circuit is about 26.96 Arms; while the input current of the bridgeless power factor improvement circuit in this application is about 24.86 Arms. Numerically, the input current of the bridgeless power factor improvement circuit in this application achieves an 8% reduction.

[0071] Based on this, since the voltage V of both the first energy storage capacitor C1 and the second energy storage capacitor C2 is equal to half of the preset output voltage Vdc, the following condition is satisfied: V = 1 / 2Vdc ensures that the discharge current in each operating state is less than the current input to the energy storage capacitor in existing technologies, thereby reducing the input current flowing through the corresponding main switch and thus reducing switch losses. Simultaneously, within any AC input cycle, the sum of the voltages across the first energy storage capacitor C1 and the second energy storage capacitor C2 equals the preset output voltage Vdc, thus achieving voltage boosting.

[0072] In summary, this application can improve the input power factor and adjust the on / off state of the corresponding main switch in each working state through the switch control module to supply power to the corresponding energy storage capacitor, so that its capacitance value is equal to half of the preset output voltage. In this way, by reducing the input current flowing through the corresponding main switch, the switching transistor loss is reduced and the boost efficiency is improved.

[0073] Based on the same design concept, this application embodiment also provides a bridgeless power factor improvement system, which includes the bridgeless power factor improvement circuit of any of the first aspects above, so as to reduce switching transistor losses and improve boost efficiency while improving the input power factor.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A bridgeless power factor correction circuit, characterized in that, The bridgeless power factor improvement circuit includes: an AC power supply module, a switching module, a first capacitor module, and a switching control module; the switching module includes at least a first main switch transistor and a second main switch transistor; the first capacitor module includes a first energy storage capacitor and a second energy storage capacitor; The switch control module is connected to the control terminal of the first main switch and the control terminal of the second main switch; the first terminal of the AC power supply module is connected to the first terminal of the first energy storage capacitor and the first terminal of the first main switch; the second terminal of the AC power supply module is connected to the first terminal of the second main switch, the second terminal of the first energy storage capacitor, and the first terminal of the second energy storage capacitor; the second terminal of the second energy storage capacitor, the second terminal of the first main switch, and the second terminal of the second main switch are all grounded; For any AC input cycle, the bridgeless power factor improvement circuit includes two operating states, and for any operating state, the switch control module is used to adjust the on / off state of the main switch tube in the current operating state to supply power to the corresponding energy storage capacitor. In each of the aforementioned operating states, the voltage values ​​between the energy storage capacitors are the same and equal to half of the preset output voltage, in order to reduce the input current flowing through the corresponding main switch transistor.

2. The bridgeless power factor improvement circuit according to claim 1, characterized in that, The bridgeless power factor improvement circuit further includes a second capacitor module, which includes a plurality of electrolytic capacitors connected in parallel; the first terminal of the plurality of electrolytic capacitors connected in parallel is connected to the first terminal of the first energy storage capacitor; the second terminal of the plurality of electrolytic capacitors connected in parallel is grounded. The capacitance values ​​of all the electrolytic capacitors are the same and equal to the total capacitance value of the first capacitor module.

3. The bridgeless power factor improvement circuit according to claim 2, characterized in that, The capacitance value of the first energy storage capacitor and / or the second energy storage capacitor is equal to twice the capacitance value between each of the electrolytic capacitors.

4. The bridgeless power factor improvement circuit according to claim 1 or 2, characterized in that, The switching module further includes an auxiliary switching transistor, the first end of which is connected to the first end of the second main switching transistor; the second end of which is connected to the second end of the first energy storage capacitor and the first end of the second energy storage capacitor; and the switching control module is also connected to the control terminal of the auxiliary switching transistor.

5. The bridgeless power factor improvement circuit according to claim 4, characterized in that, When the first operating state is in the positive half-cycle of the AC input, the first operating state includes the first discharge mode; When in the first discharge mode, both the first main switch and the second main switch are turned off, and the auxiliary switch is turned on.

6. The bridgeless power factor improvement circuit according to claim 4, characterized in that, When the second operating state is in the negative half-cycle of the AC input, the second operating state includes the second discharge mode; When in the second discharge mode, the first main switch, the second main switch, and the auxiliary switch are all turned off.

7. The bridgeless power factor improvement circuit according to claim 4, characterized in that, When the AC power supply module includes an AC power supply unit and an energy storage inductor; the positive terminal of the AC power supply unit is connected to the first terminal of the energy storage inductor, and the second terminal of the energy storage inductor is connected to the first terminal of the first energy storage capacitor; the negative terminal of the AC power supply unit is connected to the first terminal of the second main switch.

8. The bridgeless power factor improvement circuit according to claim 7, characterized in that, When the first operating state is in the positive half-cycle of the AC input, the first operating state also includes a first charging mode; When in the first charging mode, the first main switch is turned on, while the auxiliary switch and the second main switch are all turned off.

9. The bridgeless power factor improvement circuit according to claim 7, characterized in that, When the second operating state is in the negative half-cycle of the AC input, the second operating state also includes a second charging mode; When in the second charging mode, both the first main switch and the auxiliary switch are turned off, while the second main switch is turned on.

10. A bridgeless power factor improvement system, characterized in that, The bridgeless power factor improvement system includes the bridgeless power factor improvement circuit according to any one of claims 1 to 9.

Images