A power factor correction circuit, power adapter and control method

Abstract

The application provides a power factor correction circuit, a power adapter and a control method. When an AC power source is in a positive half cycle and a negative half cycle respectively, a controller controls a switching device in a switching tube module to be turned off to form different topological structures, so as to boost or buck the output voltage of the AC power source to a set voltage. When the AC power input by the AC power source is in the positive half cycle, the power factor correction circuit is equivalent to a boost circuit. When the AC power input by the AC power source is in the negative half cycle, the power factor correction circuit is equivalent to a boost-buck circuit. Due to the characteristic that the output voltages of the boost circuit and the boost-buck circuit are opposite to each other, the AC power source can use the same inductor when being in different positive and negative half cycles respectively, so that the cost is saved.

Description

Technical Field

[0001] This application relates to the field of electronic power converters, and in particular to a power factor correction circuit, a power adapter, and a control method. Background Technology

[0002] Currently, in the adapter field, adapters with a rated power exceeding 75W must meet the harmonic requirements of the national standard IEC 61000-3-2. IEC 61000-3-2 is a standard issued by the International Electrotechnical Commission (IEC) regarding harmonic currents of electrical equipment on the power grid. It specifies the requirements for odd harmonics, divided into four categories: A, B, C, and D. Generally, at least category D must be met. The power supply must add a power factor correction (PFC) circuit to correct the input current. The most commonly used PFC circuit topology is a rectifier bridge plus a boost (boost) PFC circuit, which is characterized by its simple control.

[0003] However, as market demands for product size gradually increase, the efficiency improvement of existing adapters using BOOST PFC circuits is limited. Therefore, bridgeless BOOST PFC circuits have emerged. Commonly used boost bridgeless topologies include H-bridge and AC switch structures. However, all of the above-mentioned bridgeless BOOST PFC circuit structures are boost topologies, with output voltage higher than the mains voltage. Therefore, the voltage stress on the subsequent stages is high, and the voltage withstand capability of the power devices and capacitors in the subsequent stages will become a bottleneck for improving working efficiency.

[0004] Therefore, it is necessary to propose a novel bridgeless PFC circuit structure that can improve working efficiency while reducing the requirements for the voltage withstand capability of power devices and capacitors in the subsequent circuit. Summary of the Invention

[0005] This application provides a power factor correction circuit, a power adapter, and a control method. Different topologies are formed by controlling the switching devices in the switching transistor module to turn off when the AC power supply is in different positive and negative half-cycles. Furthermore, due to the reverse voltage outputs of the boost circuit and the boost-buck circuit, the same inductor can be used when the AC power supply is in different positive and negative half-cycles, thereby saving costs.

[0006] In a first aspect, this application provides a power factor correction circuit, comprising a controller, a switching transistor module, an inductor, a first diode, a second diode, a third diode, a fourth diode, and a capacitor. The switching transistor module has a controllable bidirectional conduction function. The inductor is connected to the positive input terminal of the AC power supply, and the switching transistor module is connected to the negative input terminal of the AC power supply. The inductor is connected to the switching transistor module. The negative terminals of the first and second diodes are connected in parallel with the inductor. The positive terminals of the third and fourth diodes are connected in parallel with the switching transistor module. One end of the capacitor is connected to the negative terminal of the first diode, and the other end is connected to the fourth diode. The positive terminal of the capacitor is used to connect to the load. The controller is used to: control the opening and closing of the switching module when the AC power input is in the positive half-cycle, to boost the AC power output voltage to a set voltage and output it to the load, or to boost the AC power output voltage to a target voltage and output it to the load, wherein the target voltage is greater than the set voltage and greater than or equal to the AC power output voltage; and control the opening and closing of the switching module when the AC power input is in the negative half-cycle, to boost or deboost the AC power output voltage to a set voltage and output it to the load, wherein the set voltage is the rated voltage of the load.

[0007] Using the power factor correction circuit provided in this application, the controller turns off the switching devices in the switching transistor module when the AC power supply is in the positive and negative half-cycles, forming different topologies to boost or buck the AC power supply output voltage to a set voltage. When the AC power input is in the positive half-cycle, the power factor correction circuit is equivalent to a boost circuit; when the AC power input is in the negative half-cycle, the power factor correction circuit is equivalent to a buck-boost circuit. Furthermore, because the output voltages of the boost circuit and the buck-boost circuit are opposite to each other, the same inductor can be used when the AC power supply is in different positive and negative half-cycles, thus saving costs.

[0008] As one possible implementation, when the AC power input is in the positive half-cycle, the controller is specifically used to: control the switching transistor in the switching transistor module to close, so that the AC power supply, inductor, and switching transistor module form an excitation closed loop, so that the electrical energy of the AC power supply flows into the inductor and the current of the inductor increases; control the switching transistor in the switching transistor module to open, so that the AC power supply, inductor, second diode, capacitor, and fourth diode form a demagnetizing closed loop, so that the electrical energy stored in the inductor is transferred to the load through the capacitor.

[0009] When the switching device in the switching transistor module is closed, the electrical energy from the AC power supply flows to the inductor, increasing the current in the inductor and thus increasing the energy stored in the inductor, thereby transferring electrical energy from the AC power supply to the inductor. When the switching device in the switching transistor module is open, the voltage across the inductor equals the AC power supply output voltage minus the voltage across the capacitor. At this time, the current in the inductor decreases, and the electrical energy provided by the AC power supply and the electrical energy stored in the inductor are transferred to the load through the capacitor.

[0010] As one possible implementation, when the AC power input is in the negative half-cycle, the controller is specifically used to: control the switching transistor in the switching transistor module to close, so that the AC power supply, inductor, and switching transistor module form an excitation closed loop, so that the electrical energy of the AC power supply flows into the inductor and the current of the inductor increases; control the switching transistor in the switching transistor module to open, so that the inductor, first diode, capacitor, and third diode form a demagnetizing closed loop, so that the electrical energy stored in the inductor is transferred to the load through the capacitor.

[0011] When the switching device in the switching transistor module is closed, the input voltage of the AC power supply flows to the inductor, increasing the current in the inductor and thus increasing the energy stored in the inductor, thereby transferring electrical energy from the AC power supply to the inductor. When the switching device in the switching transistor module is open, the voltage across the inductor equals the voltage across the capacitor, the current in the inductor decreases, and the energy stored in the inductor is transferred to the load through the capacitor.

[0012] As one possible implementation, the controller is specifically used to: control the switching transistor in the switching transistor module to switch between closed and open states when the AC power input is in the positive half-cycle and the AC power output voltage is less than the set voltage, so as to boost the AC power output voltage to the set voltage and output it to the load, or boost the AC power output voltage to the target voltage and output it to the load.

[0013] As one possible implementation, the controller is specifically used to: when the voltage across the capacitor is equal to the set voltage, switch in the switching module switches between closed and open states to boost the AC power output voltage to the set voltage and then output it to the load; when the voltage across the capacitor is greater than the set voltage, switch in the switching module switches between closed and open states to boost the AC power output voltage to the target voltage and then output it to the load.

[0014] As one possible implementation, the controller is specifically used to: when the AC power input is in the positive half-cycle and the AC power output voltage is not less than the set voltage, control the switching transistor in the switching transistor module to switch between the closed and open states, and boost the AC power output voltage to the target voltage before outputting it to the load.

[0015] As one possible implementation, the controller is specifically used to: control the switching transistor in the switching transistor module to open when the voltage across the capacitor is equal to the AC power output voltage, so as to output the AC power output voltage to the load; and control the switching transistor in the switching transistor module to switch between closed and open states when the voltage across the capacitor is greater than the AC power output voltage, so as to boost the AC power output voltage to the target voltage and then output it to the load.

[0016] As one possible implementation, the controller is specifically used to: control the switching transistor in the switching transistor module to switch between closed and open states when the AC power input is in the negative half-cycle and the AC power output voltage is less than the set voltage, so as to boost the AC power output voltage to the set voltage and output it to the load.

[0017] As one possible implementation, the controller is specifically used to: control the switching transistor in the switching transistor module to switch between closed and open states when the AC power input is in the negative half-cycle and the AC power output voltage is not less than the set voltage, so as to reduce the AC power output voltage to the set voltage and output it to the load.

[0018] In one possible implementation, the switching module includes a first switching transistor and a second switching transistor, with the source of the first switching transistor connected to the source of the second switching transistor, the drain of the first switching transistor connected to one end of an inductor, and the drain of the second switching transistor connected to the negative input terminal of an AC power supply.

[0019] Secondly, this application provides a power adapter, including a DC-DC converter and a power factor correction circuit as described in the first aspect, wherein the input terminal of the power factor correction circuit is used to connect to an AC power source, and the output terminal of the power factor correction circuit is connected to a load through the DC-DC converter.

[0020] Thirdly, this application provides a power factor correction circuit control method applied to the power factor correction circuit of the first aspect. The method includes: when the AC power input is in the positive half-cycle, boosting the AC power output voltage to a set voltage and outputting it to the load, or boosting the AC power output voltage to a target voltage and outputting it to the load, wherein the target voltage is greater than the set voltage and greater than or equal to the AC power output voltage; when the AC power input is in the negative half-cycle, boosting or bucking the AC power output voltage to a set voltage and outputting it to the load, wherein the set voltage is the rated voltage of the load.

[0021] The technical effects that can be achieved by the second and third aspects mentioned above can be referred to the corresponding effect descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0022] Figures 1-3A schematic diagram of an existing PFC circuit structure; Figure 4 A schematic diagram of a power factor correction circuit. Figure 1 ; Figure 5A This is a schematic diagram of the excitation closed loop when the alternating current is in the positive half-cycle. Figure 5B A schematic diagram of a demagnetizing closed loop when the alternating current is in the positive half-cycle. Figure 5C This is a schematic diagram of an equivalent BOOST circuit; Figure 6A This is a schematic diagram of the excitation closed loop when the alternating current is in the negative half-cycle. Figure 6B A schematic diagram of a demagnetizing closed loop when the alternating current is in the negative half-cycle; Figure 6C This is a schematic diagram of the equivalent BOOST-BUCK circuit; Figure 7A Schematic diagram of voltage and current output Figure 1 ; Figure 7B Schematic diagram of voltage and current output Figure 2 ; Figure 7C Schematic diagram of voltage and current output Figure 3 ; Figure 7D Schematic diagram of voltage and current output Figure 4 ; Figure 7E The fifth diagram shows the output voltage and current. Figure 7F Diagram 6 shows the output voltage and current. Figure 8A Schematic diagram seven showing the output voltage and current; Figure 8B Eight is a schematic diagram showing the output voltage and current; Figure 9 This is a schematic diagram comparing the harmonic currents of this application with the harmonic standards; Figure 10 A schematic diagram of a power factor correction circuit. Figure 2 ; Figure 11A Waveform diagram of inductor in continuous mode Figure 1 ; Figure 11B Waveform diagram of inductor in discontinuous mode Figure 1 ; Figure 12A Waveform diagram of inductor in continuous mode Figure 2 ; Figure 12B Waveform diagram of inductor in discontinuous mode Figure 2 ; Figure 13 This is a flowchart of a power factor correction circuit control method. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, a further detailed description of this application will be provided below in conjunction with the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction as described in this application are illustrative based on the accompanying drawings, but changes may be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.

[0024] It should be noted that in the embodiments of this application, "connection" refers to electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as the connection between A and B. Alternatively, it can be a direct connection between A and C, a direct connection between C and B, with A and B connected through C.

[0025] (1) PFC circuit: A circuit used for power factor correction. The rectifier bridge of a conventional rectifier filter circuit only conducts when the input sinusoidal voltage is close to its peak value. The input current will have a serious non-sinusoidal characteristic, resulting in a large number of harmonic current components. At the same time, the harmonic current components may also interfere with other electrical equipment. The PFC circuit shapes the input AC current into a sinusoidal wave that is approximately the same as and in phase with the input voltage, so that the input power is as close as possible to 1.

[0026] (2) Continuous conduction mode (CCM): During a switching cycle, the inductor current never reaches 0. In other words, the inductor never "resets", meaning that the inductor flux never returns to 0 during the switching cycle, and there is still current flowing through the coil when the power transistor is closed.

[0027] (3) Discontinuous conduction mode (DCM): During the switching cycle, the inductor current always reaches 0, which means that the inductor is properly "reset", that is, when the power switch is closed, the inductor current is zero.

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this invention, "multiple" can also be understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are only used for distinguishing the descriptive purpose and should not be construed as indicating or implying relative importance or order.

[0029] In the adapter field, adapters with a rated power exceeding 75W must meet the harmonic requirements of the national standard IEC61000-3-2. However, as market demands for product size gradually increase, the efficiency improvement of existing adapters using BOOST PFC circuits is limited. Therefore, bridgeless BOOST PFC circuits have emerged, among which commonly used boost bridgeless topologies include dual-inductor structures, H-bridges, and AC switching structures.

[0030] As one possible implementation method, see [link / reference]. Figure 1 As shown, Figure 1 This is a schematic diagram of a PFC circuit with a dual-inductor structure. Figure 1 The left side shows the excitation stage of a PFC circuit with a dual-inductor structure, and the right side shows the demagnetization stage. The dashed arrows indicate the current flow direction. Using a dual-inductor structure results in low utilization of the two inductors, a larger footprint, and at least four switching devices in the circuit, thus increasing cost and making control more difficult. Furthermore, the high voltage stress in the subsequent stages places high demands on the voltage withstand capabilities of the power devices and capacitors in the later stages.

[0031] As one possible implementation method, see [link / reference]. Figure 2 As shown, Figure 2 This is a schematic diagram of a PFC circuit with an H-bridge structure. Figure 2The left side shows the excitation stage of an H-bridge PFC circuit, and the right side shows the demagnetization stage. The dashed arrows indicate the current flow. Using an H-bridge structure results in a more complex control flow. Current sampling needs to be implemented in the main circuit, leading to significant sampling losses. Furthermore, floating ground driving of the switching devices is required. Additionally, the voltage stress in the subsequent stages remains high, placing equally high demands on the voltage withstand capabilities of the power devices and capacitors in the subsequent circuitry.

[0032] As one possible implementation method, see [link / reference]. Figure 3 As shown, Figure 3 This is a schematic diagram of a PFC circuit with an AC switch structure. Figure 3 The left side shows the excitation stage of a PFC circuit with an AC switching structure, and the right side shows the demagnetization stage. If an AC switching structure is used, the switching devices still require floating ground drive, and achieving zero-voltage switching of the switching devices is not easy.

[0033] The above-mentioned bridgeless BOOST PFC circuit structures are all boost topologies, and their output voltages are all higher than the mains voltage. Therefore, the voltage stress on the subsequent stages is high, and the voltage withstand capability of the power devices and capacitors in the subsequent stages will become a bottleneck to improving working efficiency.

[0034] In view of this, this application provides a power factor correction circuit. During the positive and negative half-cycles of the AC input, the controller controls the closing and opening of the switching device, thereby forming different boost or buck-boost circuit structures in the same circuit. By utilizing the reverse output voltage characteristic of the buck-boost circuit, the circuit can share a single inductor to reduce costs. Furthermore, the buck-boost circuit can also solve the power factor correction problem during the negative half-cycle of the AC input.

[0035] See Figure 4 As shown, Figure 4 This is a schematic diagram of a power factor correction circuit. The power factor correction circuit 400 includes: a controller 401, a switching transistor module 402, an inductor 403, a first diode 404, a second diode 405, a third diode 406, a fourth diode 407, and a capacitor 408. The switching transistor module 402 has a controllable bidirectional conduction function.

[0036] Inductor 403 is connected to the positive input terminal of AC power supply 409, and switching transistor module 402 is connected to the negative input terminal of AC power supply 409. Inductor 403 is also connected to switching transistor module 402. The cathode of first diode 404 is connected to the cathode of second diode 405 and then connected in parallel with inductor 403. The anode of third diode 406 is connected to the anode of fourth diode 407 and then connected in parallel with switching transistor module 402. One end of capacitor 408 is connected to the cathode of first diode 404, and the other end is connected to the anode of fourth diode 407. Capacitor 408 is used to connect to load 410.

[0037] The controller 401 is used to control the opening and closing of the switching module 402 when the AC power input to the AC power supply 409 is in the positive half-cycle, to boost the output voltage of the AC power supply 409 to a set voltage and output it to the load 410, or to boost the output voltage of the AC power supply 409 to a set voltage and output it to the load 410, wherein the set voltage is greater than or equal to the output voltage of the AC power supply 409; when the AC power input to the AC power supply 409 is in the negative half-cycle, the controller 401 controls the opening and closing of the switching module 402 to boost or buck the output voltage of the AC power supply 409 to a set voltage and output it to the load 410, wherein the set voltage is the rated voltage of the load 410.

[0038] The controller 401 in the above embodiments can be a general-purpose central processing unit (CPU), a general-purpose processor, a digital signal processing unit (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor described above can also be a combination that implements computing functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0039] The switching devices in the switching module 402 can be one or more of various types of switching devices, such as metal oxide semiconductor field-effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), field-effect transistors (FETs), silicon carbide (SiC) power transistors, or gallium nitride (GaN) power transistors. These will not be listed individually in this embodiment. Each switching device can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the switching device to be turned on or off. When the switching device is on, current can be transferred between the first and second electrodes; when the switching device is off, no current can be transferred between the first and second electrodes. Taking a MOSFET as an example, the control electrode of the switching device is the gate. The first electrode of the switching device can be the source of the switching device, and the second electrode can be the drain of the switching device; alternatively, the first electrode can be the drain of the switching device, and the second electrode can be the source of the switching device.

[0040] The positive input terminal of the AC power supply 409 is connected to the first terminal of the inductor 403, the second terminal of the inductor 403 is connected to the first terminal of the switching transistor module 402, and the second terminal of the switching transistor module 402 is connected to the negative input terminal of the AC power supply 409.

[0041] The anode of the first diode 404 is connected to the first terminal of the inductor 403. The cathode of the first diode 404 is connected to the cathode of the second diode 405. The anode of the second diode 405 is connected to the second terminal of the inductor 403 and the cathode of the third diode 406. The anode of the third diode 406 is connected to the anode of the fourth diode 407. The cathode of the fourth diode 407 is connected to the second terminal of the switching transistor module 402. One end of the capacitor 408 is connected to the cathode of the first diode 404. The other end of the capacitor 408 is connected to the anode of the fourth diode 407. The capacitor 408 is used to connect to the load 410.

[0042] The power factor correction circuit 400 provided in this application is a combination of a BOOST circuit and a BUCK-BOOST circuit, which can share the same inductor. When the controller 401 detects that the AC power input of the AC power supply 409 is in the positive half-cycle, it boosts the output voltage of the AC power supply 409 to a set voltage and outputs it to the load 410, or boosts the output voltage of the AC power supply 409 to a set voltage and outputs it to the load 410. The set voltage is greater than the set voltage and is greater than or equal to the output voltage of the AC power supply 409.

[0043] When the controller 401 detects that the AC power input from the AC power supply 409 is in the negative half-cycle, it boosts or bucks the output voltage of the AC power supply 409 to a set voltage and then outputs it to the load. The set voltage is the rated voltage of the load.

[0044] When the AC power input to AC power supply 409 is in the positive half-cycle, refer to... Figure 5A As shown, Figure 5A This is a schematic diagram of the excitation closed loop when the AC power is in the positive half-cycle. The controller 401 is specifically used to control the closing of the switch in the switching module 402, so that the AC power supply 409, the inductor 403 and the switching module 402 form an excitation closed loop, so that the electrical energy of the AC power supply 409 flows into the inductor 403, thereby increasing the current of the inductor 403.

[0045] When the switching device in the switching module 402 is closed, the electrical energy of the AC power supply 409 flows to the inductor 403, thereby increasing the current in the inductor 403 and increasing the energy stored in the inductor, thus realizing the transfer of electrical energy from the AC power supply 409 to the inductor.

[0046] See Figure 5B As shown, Figure 5B This is a schematic diagram of a demagnetizing closed loop when the AC current is in the positive half-cycle. The controller 401 controls the switching transistor in the switching transistor module 402 to disconnect, and the AC power supply 409, inductor 403, second diode 405, capacitor 408 and fourth diode 407 form a demagnetizing closed loop to transfer the electrical energy stored in inductor 403 to load 410 through capacitor 408.

[0047] When the switching device in the switching module 402 is turned off, the voltage of the inductor 403 is equal to the output voltage of the AC power supply 409 minus the voltage of the capacitor 408. At this time, the current of the inductor 403 decreases, and the electrical energy provided by the AC power supply 409 and the electrical energy stored in the inductor 403 are transferred to the load 410 through the capacitor 408.

[0048] Therefore, when the AC power input to AC power source 409 is in the positive half-cycle, the power factor correction circuit 400 provided in this embodiment can be equivalent to: Figure 5C The diagram shows a BOOST circuit.

[0049] See Figure 6A As shown, Figure 6AThis is a schematic diagram of the excitation closed loop when the AC power supply 409 is in the negative half-cycle. When the AC power input from the AC power supply 409 is in the negative half-cycle, the controller 401 is specifically used to: control the switch in the switching module 402 to close, so that the AC power supply 409, inductor 403 and switching module 402 form an excitation closed loop, so that the electrical energy of the AC power supply 409 flows into the inductor 403, and the current of the inductor 403 increases.

[0050] Similarly, when the switching device in the switching module 402 is closed, the input voltage of the AC power supply 409 flows to the inductor 403, thereby increasing the current in the inductor 403, which in turn increases the energy stored in the inductor, thus realizing the transfer of electrical energy from the AC power supply 409 to the inductor.

[0051] See Figure 6B As shown, Figure 6B This is a schematic diagram of a demagnetizing closed loop when the AC current is in the negative half-cycle. The controller 401 controls the switch in the switching module 402 to disconnect, and the inductor 403, the first diode 404, the capacitor 408, and the third diode 406 form a demagnetizing closed loop, so that the electrical energy stored in the inductor 403 is transferred to the load 410 through the capacitor 408.

[0052] When the switching device in the switching module 402 is turned off, the voltage of the inductor 403 is equal to the voltage of the capacitor 408, the current of the inductor 403 decreases, and the energy stored in the inductor 403 is transferred to the load 410 through the capacitor 408.

[0053] Therefore, when the AC power input to AC power source 409 is in the negative half-cycle, the power factor correction circuit 400 provided in this embodiment can be equivalent to: Figure 6C The diagram shows a BOOST-BUCK circuit.

[0054] Will Figure 5C as well as Figure 6C The circuits shown, when combined, form Figure 4 The power factor correction circuit 400 shown is... Figure 5C and Figure 6C The switching devices in inductor 403 and switching transistor module 402 can be shared, thereby reducing costs.

[0055] The controller 401 in the power factor correction circuit 400 provided in this application can adjust the output voltage of the power factor correction circuit 400 based on the voltage of the load 410. As one possible implementation, when the AC power input to the AC power supply 409 is in the positive half-cycle and the output voltage of the AC power supply 409 is less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed state and the open state, so as to boost the output voltage of the AC power supply 409 to the set voltage and output it to the load 410, or boost the output voltage of the AC power supply 409 to the set voltage and output it to the load 410.

[0056] Since the maximum output voltage of AC power supply 409 may be less than the set voltage, the embodiments of this application can be divided into two specific cases: when the maximum output voltage of AC power supply 409 is not less than the set voltage. See Figure 7A As shown, Figure 7A Schematic diagram of voltage and current output Figure 1 .from Figure 7A As can be seen, when the AC power input to AC power supply 409 is in the positive half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST circuit. If the voltage of AC power supply 409 is less than the set voltage, and the voltage across capacitor 408 is equal to the set voltage, controller 401 controls the switching transistor in switching transistor module 402 to switch between closed and open states, which can boost the output voltage of AC power supply 409 to the set voltage and output it to load 410.

[0057] See Figure 7B As shown, Figure 7B Schematic diagram of voltage and current output Figure 2 .from Figure 7B As can be seen, the AC power input to AC power supply 409 is in the positive half-cycle. The power factor correction circuit 400 can be equivalent to a BOOST circuit. If the voltage of AC power supply 409 is less than the set voltage, and the voltage across capacitor 408 is greater than the set voltage, controller 401 controls the switching transistor in switching transistor module 402 to switch between closed and open states. This can boost the output voltage of AC power supply 409 to the target voltage and output it to load 410. The target voltage can be regarded as the voltage provided by AC power supply 409 plus the equivalent voltage of electrical energy stored in inductor 403.

[0058] As one possible implementation, the controller is specifically used to: when the AC power input to AC power supply 409 is in the positive half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST circuit, and when the output voltage of AC power supply 409 is not less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed and open states, boosting the output voltage of AC power supply 409 to the target voltage and then outputting it to the load 410.

[0059] See Figure 7C As shown, Figure 7C Schematic diagram of voltage and current output Figure 3 .from Figure 7C As can be seen from this, when the AC power input to AC power supply 409 is in the positive half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST circuit. If the voltage of AC power supply 409 is not less than the set voltage, and the voltage across capacitor 408 is equal to the output voltage of AC power supply 409, controller 401 controls the switching transistor in switching transistor module 402 to turn off, and outputs the output voltage of AC power supply 409 to load 410.

[0060] See Figure 7D As shown, Figure 7D Schematic diagram of voltage and current output Figure 4 .from Figure 7D As can be seen, the AC power input to AC power supply 409 is in the positive half-cycle. The power factor correction circuit 400 can be equivalent to a BOOST circuit. If the voltage of AC power supply 409 is not less than the set voltage, and the voltage across capacitor 408 is greater than the output voltage of AC power supply 409, controller 401 controls the switching transistor in switching transistor module 402 to switch between closed and open states, boosting the output voltage of AC power supply 409 to the target voltage and then outputting it to load 410.

[0061] As one possible implementation method, see [link / reference]. Figure 7E As shown, Figure 7E The diagram below shows the voltage and current output. When the AC power input to AC power supply 409 is in the negative half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST-BUCK circuit. When the output voltage of AC power supply 409 is less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed and open states, so as to boost the output voltage of AC power supply 409 to the set voltage and then output it to the load 410.

[0062] As one possible implementation method, see [link / reference]. Figure 7F As shown, Figure 7FThe diagram below shows the voltage and current output. When the AC power input to AC power supply 409 is in the negative half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST-BUCK circuit. When the output voltage of AC power supply 409 is not less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed and open states, so as to step down the output voltage of AC power supply 409 to the set voltage and output it to the load 410.

[0063] When the maximum output voltage of AC power supply 409 is less than the set voltage: since the output voltage of AC power supply 409 is always lower than the set voltage, therefore, refer to... Figure 8A As shown, Figure 8A The diagram below shows the voltage and current output. When the AC power input to AC power supply 409 is in the positive half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST circuit. When the output voltage of AC power supply 409 is less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed and open states, so as to boost the output voltage of AC power supply 409 to the set voltage and then output it to the load 410.

[0064] See Figure 8B As shown, Figure 8B The diagram below shows the voltage and current output. When the AC power input to AC power supply 409 is in the negative half-cycle, the power factor correction circuit 400 can be equivalent to a BOOST-BUCK circuit. When the output voltage of AC power supply 409 is less than the set voltage, the controller 401 controls the switching transistor in the switching transistor module 402 to switch between the closed and open states, so as to boost the output voltage of AC power supply 409 to the set voltage and then output it to the load 410.

[0065] See Figure 9 As shown, Figure 9 This is a schematic diagram comparing the harmonic current of this application with the harmonic standard. Figure 9 The horizontal axis represents the harmonic order, and the vertical axis represents the magnitude of the harmonic current. (Reference) Figures 7A-8B As shown, when the maximum output voltage of AC power supply 409 is less than the set voltage, its current is closer to a sine wave, and therefore the harmonic current is smaller. When the maximum output voltage of AC power supply 409 is not less than the set voltage, although its current waveform is slightly distorted, the harmonic current can still meet the harmonic requirements of the national standard IEC61000-3-2.

[0066] To achieve the switching device being turned off separately during the positive and negative half-cycles, refer to... Figure 10As shown, in one possible implementation, the switching module 402 includes a first switching transistor 4021 and a second switching transistor 4022. The source of the first switching transistor 4021 is connected to the source of the second switching transistor 4022, the drain of the first switching transistor 4021 is connected to one end of the inductor 403, and the drain of the second switching transistor is connected to the negative input terminal of the AC power supply 409. By designing the top-side switching transistor, the problem of the switching device being turned off during the positive and negative half-cycles can be solved.

[0067] In this embodiment, when the current of load 410 is large, it operates in CCM mode (Continuously On Mode). As the current of load 410 gradually decreases, the harmonic current also decreases overall. If the current of inductor 403 further decreases, it will enter DCM mode. Operating in DCM mode can relatively reduce power consumption and improve conversion efficiency. Specifically, in DCM mode, when the current of inductor 403 is 0, oscillation will occur. Furthermore, while the output voltage is independent of the current of load 410 in CCM mode, in DCM mode, the output voltage of the power factor correction circuit is affected by the load 410. To maintain a constant voltage, the duty cycle of the PWM control signal of the switching transistor module 402 controlled by controller 401 can change with the change of the current of load 410.

[0068] When the AC input to AC power supply 409 is in the positive half-cycle, the power factor correction circuit 400 is equivalent to a BOOST circuit. See the waveform diagram of inductor 403 in continuous mode. Figure 11A As shown. Figure 11A In the diagram, PWM is the PWM control signal of controller 401 controlling switching module 402, VL is the voltage value of inductor 403, IL is the current value of inductor 403, Vsw is the voltage value at the connection point between switching module 402 and inductor 403, Vin is the input voltage of AC power supply 409, and Vout is the output voltage of AC power supply 409. For a waveform diagram of inductor 403 in discontinuous mode when the AC input to AC power supply 409 is in the positive half-cycle, please refer to [reference needed]. Figure 11B As shown.

[0069] When the AC input to AC power supply 409 is in the negative half-cycle, the power factor correction circuit 400 is equivalent to a BOOST-BUCK circuit. See the waveform diagram of inductor 403 in continuous mode. Figure 12A As shown, when the AC input to AC power supply 409 is in the negative half-cycle, the waveform diagram of inductor 403 in discontinuous mode is shown in the figure. Figure 12B As shown.

[0070] The controller 401 can determine the specific operating mode based on the load power and the voltage and current of the load 410. When the load power is small or the output current is small, the discontinuous mode can be used, while when the load power is large or the output current is large, the continuous mode can be used.

[0071] Using the power factor correction circuit 400 provided in this application, the controller turns off the switching devices in the switching transistor module when the AC power supply is in the positive and negative half-cycles, forming different topologies to boost or buck the AC power supply output voltage to a set voltage. When the AC power input is in the positive half-cycle, the power factor correction circuit is equivalent to a boost circuit; when the AC power input is in the negative half-cycle, the power factor correction circuit is equivalent to a buck-boost circuit. Because the output voltages of the boost circuit and the buck-boost circuit are opposite, the same inductor can be used when the AC power supply is in different positive and negative half-cycles, thus saving costs. Furthermore, since the switching devices in the switching transistor module 402 have body diodes, the problem of turning off during positive and negative half-cycles can be solved by setting up opposing switching transistors.

[0072] Based on the same concept, this application also provides a power factor correction circuit control method, see reference. Figure 13 As shown, Figure 13 This is a flowchart of a power factor correction circuit control method. The control method includes the following steps: Step S1301: Controller 401 determines whether the AC power input from AC power source 409 is in the positive half-cycle or the negative half-cycle. If it is in the positive half-cycle, then execute step S1302; if it is in the negative half-cycle, then execute step S1303.

[0073] Step S1302: The controller 401 compares the set voltage with the output voltage of the AC power supply 409. If the set voltage is less than the output voltage of the AC power supply 409, then step S13021 is executed; otherwise, step S13022 is executed.

[0074] Step S13021: The controller 401 determines the relationship between the voltage across the capacitor 408 and the set voltage. When the voltage across the capacitor 408 is equal to the set voltage, step S130211 is executed. When the voltage across the capacitor 408 is greater than the set voltage, step S130212 is executed.

[0075] Step S130211: The switching transistor in the switching transistor module 402 of the controller 401 switches between closed and open states, boosting the output voltage of the AC power supply 409 to a set voltage before outputting it to the load 410. Specifically, the switching transistor in the control switching transistor module 402 switches between closed and open states, creating a closed-loop excitation current flow from the first terminal of the AC power supply 409 → inductor 403 → switching transistor module 402 → second terminal of the AC power supply 409. This allows the electrical energy of the AC power supply 409 to flow into the inductor 403, increasing the current in the inductor 403 and boosting the output voltage of the AC power supply 409 to the set voltage before outputting it to the load.

[0076] Step S130212: The switching transistor in the switching transistor module 402 of the controller 401 switches between closed and open states, boosting the output voltage of the AC power supply 409 to the target voltage before outputting it to the load 410. Specifically, the switching device in the control switching transistor module 402 switches between closed and open states, creating a closed-loop excitation current flow from the first terminal of the AC power supply 409 → inductor 403 → switching transistor module 402 → second terminal of the AC power supply 409. This allows the electrical energy of the AC power supply 409 to flow into the inductor 403, increasing the current in the inductor 403 and boosting the output voltage of the AC power supply 409 to the target voltage before outputting it to the load 410.

[0077] Step S13022: The controller 401 determines the relationship between the voltage across the capacitor 408 and the set voltage. When the voltage across the capacitor 408 is equal to the output voltage of the AC power supply 409, step S130221 is executed. When the voltage across the capacitor 408 is greater than the set voltage, step S130222 is executed.

[0078] Step S130221: Controller 401 controls the switching transistor in switching module 402 to turn off, outputting the AC power supply 409 output voltage to load 410. Specifically, controller 401 controls the switching transistor in switching module 402 to turn off, so that the voltage across capacitor 408 changes with the output voltage of AC power supply 409.

[0079] Step S130222: Controller 401 controls the switching transistors in switching module 402 to switch between closed and open states, boosting the output voltage of AC power supply 409 to the target voltage before outputting it to load 410. Specifically, controlling the switching transistors in switching module 402 to switch between closed and open states creates a closed-loop excitation current flow from the first terminal of AC power supply 409 → inductor 403 → switching module 402 → second terminal of AC power supply 409. This allows electrical energy from AC power supply 409 to flow into inductor 403, increasing the current in inductor 403 and boosting the output voltage of AC power supply 409 to the target voltage before outputting it to load 410.

[0080] Step S1303: Controller 401 compares the set voltage with the output voltage of AC power supply 409. If the set voltage is less than the output voltage of AC power supply 409, then step S13031 is executed; otherwise, step S13032 is executed.

[0081] Step S13031: Controller 401 controls the switching transistors in switching module 402 to switch between closed and open states, so as to boost the output voltage of AC power supply 409 to a set voltage and then output it to load 410. Specifically, controller 401 sends control signals to the switching transistors in switching module 402 to switch between closed and open states, causing a closed-loop current to flow sequentially through the second terminal of AC power supply 409 → switching module 402 → inductor 403 → first terminal of AC power supply 409, thereby boosting the output voltage of AC power supply 409 to the set voltage and then outputting it to load 410.

[0082] Step S13032: Controller 401 controls the switching transistors in switching module 402 to switch between closed and open states, thereby stepping down the output voltage of AC power supply 409 to a set voltage before outputting it to load 410. Specifically, controller 401 sends control signals to the switching transistors in switching module 402, controlling them to switch between closed and open states. This creates a closed-loop current flow from the second terminal of AC power supply 409 → switching module 402 → inductor 403 → first terminal of AC power supply 409, thus stepping down the output voltage of AC power supply 409 to the set voltage before outputting it to load 410.

[0083] Based on the same concept, this application also provides a power adapter, including a DC-DC converter and a power factor correction circuit 400 as described in the above embodiment, wherein the input terminal of the power factor correction circuit 400 is used to connect to an AC power supply 409, and the output terminal of the power factor correction circuit 400 is connected to a load 410 through the DC-DC converter.

[0084] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0086] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0087] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0088] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A power factor correction circuit, characterized in that, The circuit includes: a controller, a switching module, an inductor, a first diode, a second diode, a third diode, a fourth diode, and a capacitor. The switching module has a controllable bidirectional conduction function. The inductor is connected to the positive input terminal of the AC power supply, the switching transistor module is connected to the negative input terminal of the AC power supply, and the inductor is connected to the switching transistor module; the negative terminal of the first diode is connected to the negative terminal of the second diode and then connected in parallel with the inductor; the positive terminal of the third diode is connected to the positive terminal of the fourth diode and then connected in parallel with the switching transistor module; one end of the capacitor is connected to the negative terminal of the first diode, and the other end is connected to the positive terminal of the fourth diode; the capacitor is used to connect in parallel with the load. The controller is configured to: control the closing and opening of the switching module when the AC power input is in the positive half-cycle, to boost the AC power output voltage to a set voltage and output it to the load, or to boost the AC power output voltage to a target voltage and output it to the load, wherein the target voltage is greater than the set voltage and greater than or equal to the AC power output voltage; and control the closing and opening of the switching module when the AC power input is in the negative half-cycle, to boost or buck the AC power output voltage to a set voltage and output it to the load, wherein the set voltage is the rated voltage of the load.

2. The power factor correction circuit according to claim 1, characterized in that, When the AC power input is in the positive half-cycle, the controller is specifically used for: By controlling the switching transistor in the switching transistor module to close, the AC power supply, the inductor, and the switching transistor module form an excitation closed loop, so that the electrical energy of the AC power supply flows into the inductor, and the current of the inductor increases; The switching transistor in the control switching transistor module is turned off, and the AC power supply, the inductor, the second diode, the capacitor, and the fourth diode form a demagnetizing closed loop to transfer the electrical energy stored in the inductor to the load through the capacitor.

3. The power factor correction circuit according to claim 1, characterized in that, When the AC power input is in the negative half-cycle, the controller is specifically used for: By controlling the switching transistor in the switching transistor module to close, the AC power supply, the inductor, and the switching transistor module form an excitation closed loop, so that the electrical energy of the AC power supply flows into the inductor, and the current of the inductor increases; The switching transistor in the control switching transistor module is turned off, and the inductor, the first diode, the capacitor, and the third diode form a demagnetizing closed loop, so that the electrical energy stored in the inductor is transferred to the load through the capacitor.

4. The power factor correction circuit according to any one of claims 1-3, characterized in that, The controller is specifically used for: When the AC power input is in the positive half-cycle and the AC power output voltage is less than the set voltage, the switching transistor in the switching transistor module is controlled to switch between the closed and open states, so as to boost the AC power output voltage to the set voltage and output it to the load, or boost the AC power output voltage to the target voltage and output it to the load.

5. The power factor correction circuit according to claim 4, characterized in that, The controller is specifically used for: When the voltage across the capacitor is equal to the set voltage, the switching transistor in the switching transistor module switches between a closed state and an open state, boosting the AC power output voltage to the set voltage and then outputting it to the load; When the voltage across the capacitor is greater than the set voltage, the switching transistor in the switching transistor module switches between a closed state and an open state, boosting the AC power output voltage to the target voltage and then outputting it to the load.

6. The power factor correction circuit according to any one of claims 1-3 or 5, characterized in that, The controller is specifically used for: When the AC power input is in the positive half-cycle, and the AC power output voltage is not less than the set voltage, the switching transistor in the switching transistor module is controlled to switch between the closed and open states, so as to boost the AC power output voltage to the target voltage and then output it to the load.

7. The power factor correction circuit according to claim 6, characterized in that, The controller is specifically used for: When the voltage across the capacitor is equal to the AC power supply output voltage, the switching transistor in the switching transistor module is turned off, and the AC power supply output voltage is output to the load. When the voltage across the capacitor is greater than the AC power supply output voltage, the switching transistor in the switching transistor module is controlled to switch between closed and open states, thereby boosting the AC power supply output voltage to the target voltage and then outputting it to the load.

8. The power factor correction circuit according to any one of claims 1-3, 5 or 7, characterized in that, The controller is specifically used for: When the AC power input is in the negative half-cycle and the AC power output voltage is less than the set voltage, the switching transistor in the switching transistor module is controlled to switch between closed and open states to boost the AC power output voltage to the set voltage and then output it to the load.

9. The power factor correction circuit according to any one of claims 1-3, 5 or 7, characterized in that, The controller is specifically used for: When the AC power input is in the negative half-cycle and the AC power output voltage is not less than the set voltage, the switching transistor in the switching transistor module is controlled to switch between closed and open states to reduce the AC power output voltage to the set voltage and output it to the load.

10. The power factor correction circuit according to any one of claims 1-3, 5 or 7, characterized in that, The switching module includes a first switching transistor and a second switching transistor. The source of the first switching transistor is connected to the source of the second switching transistor, the drain of the first switching transistor is connected to one end of the inductor, and the drain of the second switching transistor is connected to the negative input terminal of the AC power supply.

11. A power adapter, characterized in that, The power adapter includes a DC-DC converter and a power factor correction circuit as described in any one of claims 1-10, wherein the input terminal of the power factor correction circuit is used to connect to an AC power source, and the output terminal of the power factor correction circuit is connected to a load through the DC-DC converter.

12. A power factor correction circuit control method, applied to the power factor correction circuit as described in any one of claims 1-10, characterized in that, The method includes: When the AC power input is in the positive half-cycle, the AC power output voltage is boosted to a set voltage and then output to the load, or the AC power output voltage is boosted to a target voltage and then output to the load, wherein the target voltage is greater than the set voltage and greater than or equal to the AC power output voltage; when the AC power input is in the negative half-cycle, the AC power output voltage is boosted or debossed to a set voltage and then output to the load, wherein the set voltage is the rated voltage of the load.

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