Bridgeless PFC circuit
By employing an active rectifier bridge composed of four power transistors and a controller, a bridgeless PFC circuit is developed, which solves the problem of high conduction loss in traditional bridged PFC circuits. This results in a more efficient, easily upgradeable, and intelligent PFC circuit, simplifying the control logic and improving the system's reliability and applicability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-10
AI Technical Summary
Traditional bridged PFC circuits suffer from severe conduction losses due to diode rectifier bridges, which limits the improvement of power system efficiency, especially in high-power or high-current applications. Furthermore, existing bridgeless PFC topologies are highly complex and costly.
An active rectifier bridge consisting of four power transistors replaces the traditional diode rectifier bridge. Combined with a boost circuit and a controller, the controller controls the power transistors to conduct alternately according to the polarity of the AC input voltage, simplifying the control logic. It is suitable for various PFC power circuits such as Boost, Buck, and Flyback.
It significantly reduces conduction losses, improves PFC circuit efficiency, reduces product iteration and production costs, simplifies control logic, enhances system reliability and applicability, and supports intelligent monitoring.
Smart Images
Figure CN121841099A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power electronics technology, and in particular to a bridgeless PFC circuit. Background Technology
[0002] With the rapid development of power electronics technology, various electronic devices are increasingly demanding higher power density and efficiency from switching power supplies. However, in the AC / DC conversion process, traditional switching power supplies typically use a rectifier bridge composed of four diodes to rectify the AC input. While this rectifier circuit is simple in structure, it causes severe waveform distortion in the grid-side input current, presenting as a sharp pulse near the peak value instead of a sine wave in phase with the input voltage. This phenomenon directly leads to problems such as low power factor and excessive current harmonic content in the equipment.
[0003] Power factor is a key indicator for measuring the efficiency of electricity utilization, with an ideal value of 1. A low power factor means that a large amount of apparent power drawn by equipment from the grid is not used for actual work, but rather circulates in the grid as reactive power. This not only wastes electrical energy but also increases line losses, pollutes and burdens the public power grid, and may even affect the normal operation of other equipment on the same grid. Therefore, many countries and regions around the world have introduced mandatory regulations that set clear requirements for the input power factor and harmonic emissions of electronic equipment.
[0004] To address these issues, power factor correction (PFC) technology has emerged. Currently, the mainstream solution is active power factor correction (PFC) circuits. The most common APFC topology is a bridge-based PFC topology based on a boost converter, which consists of a diode rectifier bridge and a PFC boost converter. This topology uses a controller to perform high-frequency PWM control on the subsequent boost switch, forcing the input current waveform to track the input voltage waveform, thereby improving the power factor to above 0.95 and meeting regulatory requirements.
[0005] However, traditional bridged PFC topologies have an inherent efficiency bottleneck: under any operating condition, the input current must continuously flow through both diodes in the diode rectifier bridge. The inherent forward voltage drop of the diodes generates a fixed conduction loss. This loss is particularly significant in high-power or high-current applications, severely limiting further improvements in the overall power system efficiency and posing a serious heat dissipation challenge.
[0006] To address the aforementioned issues, this application proposes a bridgeless PFC circuit scheme. Summary of the Invention
[0007] The purpose of this invention is to address the problems existing in the background technology by proposing a bridgeless PFC circuit.
[0008] The technical solution of the present invention is a bridgeless PFC circuit, comprising: An active rectifier bridge consists of four power transistors connected to the AC input terminal, used to rectify the AC input into pulsed DC. The boost circuit is connected to the output of the active rectifier bridge to boost the voltage and serve as the output of the PFC circuit. The controller is used to sample the AC input voltage, current and output voltage, and output drive signals according to the sampled signals to control the operation of the power transistors of the active rectifier bridge and boost circuit.
[0009] Preferably, the active rectifier bridge includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor; The first and third power transistors are both connected to the output of the active rectifier bridge, and the second terminals of the first and third power transistors are connected to the controller; the third terminal of the first power transistor is connected to the AC input terminal and the first terminal of the second power transistor; the third terminal of the third power transistor is connected to the AC input terminal and the first terminal of the fourth power transistor. The third terminals of the second and fourth power transistors are both connected to the output terminals of the active rectifier bridge, and the second terminals of the second and fourth power transistors are connected to the controller.
[0010] Preferably, the controller's four outputs control the drive signals of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor, respectively.
[0011] Preferably, the AC input active rectifier bridge outputs a pulsed DC signal; when the AC input voltage is positive at the top and negative at the bottom, the first and fourth power transistors of the active rectifier bridge are turned on; the controller provides the drive signal of the power transistors according to the AC input sampling signal, while keeping the second and third power transistors in the off state, and keeping the first and fourth power transistors of the active rectifier bridge on, until the AC input signal is commutated.
[0012] Preferably, when the AC input signal is positive at the bottom and negative at the top, the second and third power transistors in the active rectifier bridge are turned on; the controller provides the drive signal for the power transistors according to the AC input sampling signal; at the same time, the first and fourth power transistors are kept off; and the second and third power transistors of the active rectifier bridge are kept on; until the AC input is commutated.
[0013] Preferably, the operation is repeated in each cycle of the AC input active rectifier bridge.
[0014] Preferably, the boost circuit is a Boost circuit or a PFC power circuit. A conventional PFC circuit is connected to the rear end of the active rectifier bridge, where AC input sampling (VacL and VacN) and AC (Iac) current sampling jointly realize the PFC control function.
[0015] Preferably, the PFC power circuit is a Buck topology or a flyback topology circuit.
[0016] Preferably, the Boost circuit includes a Boost inductor, a Boost rectifier diode, a Boost power transistor, and a PFC output capacitor; The output of the active rectifier bridge is connected to the first terminal of the Boost inductor, and the second terminal of the Boost inductor is connected to the first terminals of the Boost power transistor and the Boost rectifier transistor. The second terminal of the Boost power transistor is connected to the second terminal of the PFC capacitor and then to the PFC output terminal. The second terminal of the Boost rectifier transistor is connected to the first terminal of the PFC capacitor and then to the PFC output terminal. Both the Boost rectifier diode and the Boost power diode are connected to the controller to obtain drive signals.
[0017] Preferably, the Boost rectifier is a diode or a power transistor. In a conventional Boost circuit, a Boost rectifier is added in addition to the Boost power transistor. As the power increases, the Boost rectifier can also be replaced with a power transistor, controlled by a controller. The drive signals for the Boost rectifier and the Boost power transistor are complementary; that is, if the Boost power transistor is driven by a duty cycle of D, then the Boost rectifier is driven by a cycle of 1-D. Alternatively, if the Boost rectifier is a diode, the controller does not output a drive signal.
[0018] Preferably, the controller is responsible for sampling the AC input voltage, current and output voltage, and outputs the Boost drive signal through the internal PFC software control algorithm; it is also responsible for outputting the drive signal of the active rectifier bridge. In addition, the controller has a communication interface to communicate with the outside world and exchange data.
[0019] Compared with the prior art, the present invention has the following beneficial technical effects: This invention replaces the traditional diode rectifier bridge with an active rectifier bridge composed of four power transistors. Since the on-resistance of the power transistor (such as a MOSFET) is much lower than the on-voltage drop of the diode, the conduction loss in the current path is greatly reduced, thereby significantly improving the conversion efficiency of the entire PFC circuit, making it particularly suitable for high-power, high-current applications.
[0020] The circuit structure design of this invention allows for direct modification and upgrading of existing conventional bridged PFC hardware. By replacing the front-end rectifier section and updating the control logic, a traditional bridged PFC can be transformed into a high-efficiency bridgeless PFC, significantly reducing the R&D and production costs of product iteration.
[0021] Compared to other complex bridgeless PFC topologies, the active rectifier bridge control strategy of this invention is intuitive and easy to implement. The controller only needs to control the two sets of diagonal power transistors to conduct alternately according to the polarity of the AC input voltage. The logic is clear, and there is no need for complex timing control or dead-time management, which improves the reliability and robustness of the system.
[0022] The boost circuit of this invention is not limited to the traditional Boost topology, but can also be extended to various PFC power circuits such as Buck and flyback, enhancing the applicability of the solution. Meanwhile, the rectifier diodes in the Boost circuit can be flexibly configured as diodes or power transistors. When power transistors are used and complementary driving is employed, synchronous rectification can be further achieved, improving efficiency and meeting different power levels and performance requirements.
[0023] The controller integrates communication interfaces (such as UART, I2C, etc.) and can report circuit operating status, fault information and other data in real time, which facilitates intelligent monitoring, debugging and maintenance of the power system and is in line with the development trend of modern power management systems. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the system structure of the PFC circuit in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the system structure of the Boost circuit in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the system structure of the active rectifier bridge circuit in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the system structure of the PFC circuit in Embodiment 2 of the present invention. Detailed Implementation
[0025] Example 1 like Figure 1 As shown, the present invention proposes a bridgeless PFC circuit, comprising: An active rectifier bridge consists of four power transistors connected to the AC input terminal, used to rectify the AC input into pulsed DC. The boost circuit is connected to the output of the active rectifier bridge to boost the voltage and serve as the output of the PFC circuit. The controller is used to sample the AC input voltage, current and output voltage, and output drive signals according to the sampled signals to control the operation of the power transistors of the active rectifier bridge and boost circuit.
[0026] In this embodiment, as Figure 3 As shown, the active rectifier bridge includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor; The first and third power transistors are both connected to the output of the active rectifier bridge, and the second terminals of the first and third power transistors are connected to the controller; the third terminal of the first power transistor is connected to the AC input terminal and the first terminal of the second power transistor; the third terminal of the third power transistor is connected to the AC input terminal and the first terminal of the fourth power transistor. The third terminals of the second and fourth power transistors are both connected to the output terminals of the active rectifier bridge, and the second terminals of the second and fourth power transistors are connected to the controller.
[0027] As a preferred embodiment, the controller's four outputs control the drive signals of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor, respectively.
[0028] When the AC input is active rectifier bridge, its output is a pulsed DC signal; when the AC input voltage is positive at the top and negative at the bottom, the first and fourth power transistors of the active rectifier bridge are turned on; the controller gives the drive signal of the power transistors according to the AC input sampling signal, while keeping the second and third power transistors in the off state, and keeping the first and fourth power transistors of the active rectifier bridge on, until the AC input signal is commutated.
[0029] When the AC input signal is positive at the bottom and negative at the top, the second and third power transistors in the active rectifier bridge are turned on; the controller provides the drive signal for the power transistors according to the AC input sampling signal; at the same time, the first and fourth power transistors are kept off; and the second and third power transistors of the active rectifier bridge are kept on; until the AC input is commutated.
[0030] The operation is repeated in each cycle of the AC input active rectifier bridge. This transforms the bridged PFC circuit into a bridgeless PFC circuit.
[0031] In this implementation, such as Figure 2 As shown, the boost circuit is a conventional PFC circuit connected to the back end of the active rectifier bridge. The AC input sampling (VacL and VacN) and AC (Iac) current sampling together realize the PFC control function. The boost circuit includes a boost inductor, a boost rectifier diode, a boost power transistor, and a PFC output capacitor. The output of the active rectifier bridge is connected to the first terminal of the Boost inductor. The second terminal of the Boost inductor is connected to the first terminals of the Boost power transistor and the Boost rectifier. The second terminal of the Boost power transistor is connected to the second terminal of the PFC capacitor and then to the PFC output. The second terminal of the Boost rectifier is connected to the first terminal of the PFC capacitor and then to the PFC output. Both the Boost rectifier and the Boost power transistor are connected to the controller to obtain drive signals. In a conventional Boost circuit, a Boost rectifier is added in addition to the Boost power transistor. As the power increases, the Boost rectifier can also be replaced with a power transistor, controlled by the controller. The drive signals of the Boost rectifier and the Boost power transistor are complementary; that is, if the Boost power transistor is driven by a duty cycle of D, then the Boost rectifier is driven by a 1-D frequency. Alternatively, if the Boost rectifier is a diode, the controller does not output a drive signal.
[0032] The controller is responsible for sampling AC input voltage, current and output voltage, and outputs the Boost drive signal through the internal PFC software control algorithm; it is also responsible for outputting the drive signal of the active rectifier bridge. In addition, the controller has a communication interface to communicate with the outside world and exchange data.
[0033] This embodiment replaces the original diode rectifier bridge with power transistors and integrates them with the subsequent PFC circuit, truly transforming the conventional PFC circuit into a bridgeless PFC circuit to improve system efficiency and power density. Simultaneously, the overall circuit control is simple and flexible, easily integrated into the PFC control algorithm, thus shortening the development cycle and reducing development costs. Finally, since slow-speed power transistors and low-voltage power transistors can be selected in the front-end, and switching can be chosen at the AC zero-crossing point, the overall system reliability is improved.
[0034] Example 2 like Figure 4 As shown, the present invention proposes a bridgeless PFC circuit, comprising: An active rectifier bridge consists of four power transistors connected to the AC input terminal, used to rectify the AC input into pulsed DC. The boost circuit is connected to the output of the active rectifier bridge to boost the voltage and serve as the output of the PFC circuit. The boost circuit is a PFC power circuit, and can be either a Buck topology or a flyback topology circuit.
[0035] The controller is used to sample the AC input voltage, current and output voltage, and output drive signals according to the sampled signals to control the operation of the power transistors of the active rectifier bridge and boost circuit.
[0036] In this embodiment, as Figure 3As shown, the active rectifier bridge includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor; The first and third power transistors are both connected to the output of the active rectifier bridge, and the second terminals of the first and third power transistors are connected to the controller; the third terminal of the first power transistor is connected to the AC input terminal and the first terminal of the second power transistor; the third terminal of the third power transistor is connected to the AC input terminal and the first terminal of the fourth power transistor. The third terminals of the second and fourth power transistors are both connected to the output terminals of the active rectifier bridge, and the second terminals of the second and fourth power transistors are connected to the controller.
[0037] As a preferred embodiment, the controller's four outputs control the drive signals of the first power transistor, the second power transistor, the third power transistor, and the fourth power transistor, respectively.
[0038] When the AC input is active rectifier bridge, its output is a pulsed DC signal; when the AC input voltage is positive at the top and negative at the bottom, the first and fourth power transistors of the active rectifier bridge are turned on; the controller gives the drive signal of the power transistors according to the AC input sampling signal, while keeping the second and third power transistors in the off state, and keeping the first and fourth power transistors of the active rectifier bridge on, until the AC input signal is commutated.
[0039] When the AC input signal is positive at the bottom and negative at the top, the second and third power transistors in the active rectifier bridge are turned on. The controller provides drive signals to the power transistors based on the AC input sampling signal, while keeping the first and fourth power transistors off. The controller also keeps the second and third power transistors of the active rectifier bridge on until the AC input commutates. In this step, the drive signal provided for commutation is given at the AC zero-crossing point to reduce the drive and turn-on losses of the power transistors.
[0040] The operation is repeated in each cycle of the AC input active rectifier bridge. This transforms the bridged PFC circuit into a bridgeless PFC circuit.
[0041] In this implementation, such as Figure 2 As shown, the boost circuit is a conventional PFC circuit connected to the back end of the active rectifier bridge. The AC input sampling (VacL and VacN) and AC (Iac) current sampling together realize the PFC control function. The boost circuit includes a boost inductor, a boost rectifier diode, a boost power transistor, and a PFC output capacitor. The output of the active rectifier bridge is connected to the first terminal of the Boost inductor, and the second terminal of the Boost inductor is connected to the first terminals of the Boost power transistor and the Boost rectifier transistor. The second terminal of the Boost power transistor is connected to the second terminal of the PFC capacitor and then to the PFC output terminal. The second terminal of the Boost rectifier transistor is connected to the first terminal of the PFC capacitor and then to the PFC output terminal. Both the Boost rectifier transistor and the Boost power transistor are connected to the controller to obtain drive signals.
[0042] The controller is responsible for sampling the AC input voltage, current, and output voltage, and outputs the Boost drive signal through its internal PFC software control algorithm. It also handles the drive signal output for the active rectifier bridge. In addition, the controller has a communication interface for external communication and data exchange. The AC current sampling point is located before or after the active rectifier bridge.
[0043] In this invention, the controller is the brain and nerve center of the circuit, responsible for performing a series of key tasks such as sampling, calculation, control, and communication. Its specific implementation does not depend on a fixed chip model, but rather allows for the flexible selection of various types of processors or logic devices based on cost, performance, integration level, and development cycle requirements. These include, but are not limited to, MCUs, DSPs, DSCs, FPGAs, or dedicated ASIC chips. These chips are described below: An MCU is a single-chip computer that integrates a processor core, memory (ROM / RAM), and various peripheral interfaces (such as ADC, PWM, timers, and communication interfaces). It emphasizes control functions and is suitable for performing logical judgments, process management, and low-to-medium speed computing tasks.
[0044] In the circuit of this application, the MCU can sample the AC input voltage, current, and DC output voltage using its built-in ADC module. By running a PFC control algorithm (such as average current mode control), the required PWM duty cycle is calculated, and its PWM generator outputs a drive signal to control the four power transistors of the active rectifier bridge and the power transistors of the subsequent Boost circuit. Using its UART, I2C, or CAN communication interface, the system status (such as output voltage, input current, and fault flags) is reported to the host computer or system host in real time. This is suitable for low- to medium-power applications where cost is sensitive and control bandwidth requirements are not extremely high.
[0045] A DSP (Digital Signal Processor) is a microprocessor specifically optimized for high-speed, high-precision digital signal processing (such as numerous multiply-accumulate operations). It possesses powerful computing capabilities and a fast instruction cycle, making it particularly suitable for implementing complex real-time algorithms.
[0046] In this application, a DSP is the ideal choice for achieving high-performance PFC control. It can perform sampling data filtering, coordinate transformation (e.g., for complex topologies such as VIENNA rectification), and advanced PFC control algorithms (e.g., predictive current control, deadbeat control) at extremely high speeds, thereby achieving a better power factor and lower current harmonics. Its high-precision PWM module and fast ADC enable nanosecond-level precise control of the active rectifier bridge and Boost switches, ensuring smooth commutation and reducing current distortion. It is suitable for high-power, high-performance applications with extremely high requirements for dynamic response and THD performance.
[0047] The DSC (Digital Signal Controller) is a product that combines the control convenience of an MCU (Microcontroller Unit) with the powerful computing capabilities of a DSP (Digital Signal Processor). It integrates the arithmetic processing capabilities of a DSP and the rich control peripherals of an MCU within a single chip, offering both high performance and ease of use.
[0048] In this application, the DSC can run PFC mathematical algorithms as efficiently as a DSP, while managing communication interfaces and logic states as conveniently as an MCU. It can seamlessly handle both the power frequency commutation logic of an active rectifier bridge and the high-frequency PWM control of a Boost circuit simultaneously. For projects requiring strong computational power but also wanting to maintain a user-friendly development environment, the DSC is an excellent compromise.
[0049] An FPGA (Field-Programmable Gate Array) is a semiconductor device that is programmed by a user in the field using a hardware description language such as VHDL or Verilog. Internally, it consists of a large number of programmable logic units, allowing for true parallel processing and highly customized digital circuitry.
[0050] This application utilizes FPGAs to implement fully hardware-based control logic. For example, dedicated logic modules can be designed to process the driving of the active rectifier bridge and the generation of PWM for the Boost converter in parallel, with extremely low response latency and extremely high determinism. Multiple completely independent and interference-free PWM signals can be generated simultaneously to precisely control six or more power transistors (four in the active rectifier bridge and two in the synchronous Boost converter), a feat unmatched by traditional processor sequential execution. This approach is suitable for R&D phases that prioritize ultimate performance and reliability (e.g., aerospace, industrial control) or require specialized customized functions.
[0051] Application-specific integrated circuits (ASICs) are integrated circuits tailored to specific applications or users. Once designed and manufactured, their functionality is fixed and cannot be changed like that of FPGAs. Their purpose is to be optimally designed to achieve a specific function, in order to achieve the highest performance, lowest power consumption, or smallest size.
[0052] In this application, an ASIC controller is specifically designed for the bridgeless PFC topology described in this invention. This chip will internally integrate the PFC control algorithm, the active rectifier bridge commutation logic, and the communication protocol. In mass production, ASICs have the absolute advantages of **extremely low cost, smallest size, and highest reliability**. It integrates the core functions of the entire control system into a single chip, representing the ultimate form for productization and commercialization after the technology matures.
[0053] In the bridgeless PFC circuit of this invention, the selection of the controller offers great flexibility: In prototype development or low-to-medium power products, MCUs or DSCs can be selected to balance cost and performance.
[0054] In high-end, high-power products, DSPs or FPGAs can be used to achieve optimal performance and fast dynamic response.
[0055] Once mass production is achieved and the technology is fully mature, dedicated ASICs can be developed to achieve extremely high cost-effectiveness and competitiveness.
[0056] This broad compatibility ensures that the technical solution of the present invention can adapt to different market demands and product positioning, greatly enhancing its practical value and industrial application prospects.
[0057] This embodiment, through an innovative active rectifier bridge architecture and flexible control scheme, successfully achieves high efficiency, easy upgrade and intelligence of PFC circuit without significantly increasing system complexity and cost, effectively overcoming the inherent defects of traditional bridged PFC and existing bridgeless PFC technologies.
[0058] Example 3 This embodiment provides an electronic device. It should be noted that the computer system of the electronic device in this embodiment is only an example and should not impose any limitations on the function and scope of use of the embodiments of the present invention.
[0059] In this embodiment, the computer system includes a central processing unit (CPU), which can perform various appropriate actions and processes based on a program stored in read-only memory (ROM) or a program loaded from storage into random access memory (RAM), such as executing the operating steps of the bridgeless PFC circuit described in the above embodiment. The RAM also stores various programs and data required for system operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output interfaces are also connected to the bus.
[0060] The following components are connected to the input / output interface: input sections including keyboards, mice, etc.; output sections including cathode ray tubes (CRTs), liquid crystal displays (LCDs), and speakers; storage sections including hard drives; and communication sections including network interface cards such as LAN (Local Area Network) cards and modems. The communication section performs communication processing via a network such as the Internet. Drives are also connected to the input / output interface as needed. Removable media, such as disks, optical discs, magneto-optical discs, semiconductor memories, etc., are installed on the drive as needed so that computer programs read from them can be installed into the storage section as required.
[0061] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing computer programs for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium. When the computer program is executed by a central processing unit, it performs various functions defined in the system of the present invention.
[0062] It should be noted that the computer-readable medium shown in the embodiments of the present invention can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the present invention, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, wherein a computer-readable computer program is carried. The transmitted data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The computer program contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.
[0063] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.
[0064] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.
[0065] According to one aspect of the present invention, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and executes the computer instructions, causing the computer device to perform the methods provided in the various alternative implementations described above.
[0066] In another aspect, the present invention also provides a computer-readable medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable medium carries one or more programs that, when executed by the electronic device, cause the electronic device to implement the steps of the bridgeless PFC circuit described in the above embodiments.
[0067] It should be noted that although several modules or units of the device for performing actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.
[0068] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, portable hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the method according to the embodiments of the present invention.
[0069] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein.
[0070] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.
Claims
1. A bridgeless PFC circuit, characterized in that, include: An active rectifier bridge consists of four power transistors connected to the AC input terminal, used to rectify the AC input into pulsed DC. The boost circuit is connected to the output of the active rectifier bridge to boost the voltage and serve as the output of the PFC circuit. The controller is used to sample the AC input voltage, current and output voltage, and output drive signals according to the sampled signals to control the operation of the power transistors of the active rectifier bridge and boost circuit.
2. The bridgeless PFC circuit according to claim 1, characterized in that, The active rectifier bridge includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor; The first and third power transistors are both connected to the output of the active rectifier bridge, and the second terminals of the first and third power transistors are connected to the controller; the third terminal of the first power transistor is connected to the AC input terminal and the first terminal of the second power transistor; the third terminal of the third power transistor is connected to the AC input terminal and the first terminal of the fourth power transistor. The third terminals of the second and fourth power transistors are both connected to the output terminals of the active rectifier bridge, and the second terminals of the second and fourth power transistors are connected to the controller.
3. The bridgeless PFC circuit according to claim 2, characterized in that, The controller has four outputs that control the drive signals of the first, second, third, and fourth power transistors, respectively.
4. The bridgeless PFC circuit according to claim 3, characterized in that, An AC input active rectifier bridge outputs a pulsed DC signal. When the AC input voltage is positive at the top and negative at the bottom, the first and fourth power transistors of the active rectifier bridge are turned on. The controller provides drive signals for the power transistors based on the AC input sampling signal, while keeping the second and third power transistors off and keeping the first and fourth power transistors of the active rectifier bridge on until the AC input signal is commutated.
5. The bridgeless PFC circuit according to claim 3, characterized in that, When the AC input signal is positive at the bottom and negative at the top, the second and third power transistors in the active rectifier bridge are turned on; the controller provides the drive signal for the power transistors according to the AC input sampling signal; at the same time, the first and fourth power transistors are kept off; and the second and third power transistors of the active rectifier bridge are kept on; until the AC input is commutated.
6. The bridgeless PFC circuit according to claim 4 or 5, characterized in that, The operation is repeated in each cycle of the AC input active rectifier bridge.
7. A bridgeless PFC circuit according to claim 1, characterized in that, The boost circuit is either a Boost circuit or a PFC power circuit.
8. A bridgeless PFC circuit according to claim 7, characterized in that, The PFC power circuit is a Buck topology or flyback topology circuit.
9. A bridgeless PFC circuit according to claim 7, characterized in that, The Boost circuit includes a Boost inductor, a Boost rectifier diode, a Boost power transistor, and a PFC output capacitor; The output of the active rectifier bridge is connected to the first terminal of the Boost inductor, and the second terminal of the Boost inductor is connected to the first terminals of the Boost power transistor and the Boost rectifier transistor. The second terminal of the Boost power transistor is connected to the second terminal of the PFC capacitor and then to the PFC output terminal. The second terminal of the Boost rectifier transistor is connected to the first terminal of the PFC capacitor and then to the PFC output terminal. Both the Boost rectifier diode and the Boost power diode are connected to the controller to obtain drive signals.
10. A bridgeless PFC circuit according to claim 9, characterized in that, Boost rectifier diodes are either diodes or power transistors.