A voltage regulation circuit and power supply for a single-ended PFC power supply

Abstract

A voltage regulation circuit for a single-ended PFC power supply includes a feedback terminal, a power supply terminal, a voltage divider module, a switching module, and a main control module. The control terminal of the main control module is connected to the controlled terminal of the switching module. The power supply terminal is connected to the voltage divider module through the switching module. The feedback terminal is grounded through the voltage divider module. The main control module controls the conduction state of the switching module. The switching module changes the equivalent resistance value of the voltage divider module in the conduction state. The feedback terminal receives the output voltage of the voltage divider module. The power supply terminal provides the operating voltage to the switching module and the voltage divider module. This embodiment of the invention dynamically adjusts the output voltage by controlling the switching module to change the equivalent resistance value of the voltage divider module. This solves the problem of low efficiency in subsequent circuits caused by a fixed bus voltage in a single-ended PFC power supply, and has advantages such as flexible bus voltage adjustment, optimized efficiency of subsequent circuits, and reduced standby power consumption.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, specifically to a voltage regulation circuit for a single-ended PFC power supply. Background Technology

[0002] With the widespread use of mobile terminal devices, laptops and portable electronic products, power adapters supporting the USB-PD fast charging protocol have been widely used. In order to meet the demand for multi-port output, existing PD power supplies generally adopt a multi-stage power conversion architecture. Its typical structure is as follows: AC input is boosted to high voltage DC through a power factor correction circuit, then undergoes a voltage conversion through a quasi-resonant flyback circuit, and finally the subsequent Buck circuit performs a secondary step-down adjustment for different output ports to obtain multiple voltage levels such as 5V, 9V, 15V, and 20V.

[0003] However, there are two main types of existing PD power supplies. One type is a three-stage structure PFC+QR+Buck. In this embodiment, an independent PFC is used to increase the power factor (PF), and then the QR generates the intermediate bus voltage. The subsequent multi-channel Buck distributes the voltage / power according to the protocol. Its disadvantages are that there are many device stages, the size and cost are high, and each channel Buck needs to bear a large voltage difference when the bus voltage is fixed. The efficiency and temperature rise are not ideal when fully loaded and concurrent, and the standby loss is also relatively large under light load.

[0004] Secondly, integrating PFC and QR into a single-ended structure eliminates the need for a separate PFC stage and simplifies magnetic components, which helps reduce size and cost. However, the primary-side output voltage is usually fixed and difficult to adjust according to the power demand, causing the downstream Buck converter to deviate from its optimal operating point. This makes it difficult for the system to simultaneously achieve high efficiency across multiple ports and low standby power consumption. Therefore, it is urgent to implement multi-level adjustable primary-side setpoints under this integrated architecture to bring the bus voltage closer to the downstream target, thereby reducing step-down losses and improving full-load and standby efficiency. Utility Model Content

[0005] The purpose of this utility model is to address the defects and shortcomings of the existing technology by providing a solution with [specific features].

[0006] On one hand, this utility model provides a voltage regulation circuit for a single-ended PFC power supply, including a feedback terminal, a power supply terminal, a voltage divider module, a switching module, and a main control module. The control terminal of the main control module is connected to the controlled terminal of the switching module. The power supply terminal is connected to the voltage divider module through the switching module. The feedback terminal is grounded through the voltage divider module. The main control module is used to control the conduction state of the switch module. The switch module is used to change the equivalent resistance value of the voltage divider module in the conduction state. The feedback terminal is used to receive the output voltage of the voltage divider module. The power supply terminal provides the operating voltage to the switch module and the voltage divider module.

[0007] Furthermore, the switching module includes an optocoupler unit, a first switching unit, and a second switching unit; the voltage divider module includes a first resistor branch, a second resistor branch, and a third resistor branch; the feedback terminal is connected to the input terminals of the first resistor branch, the second resistor branch, and the third resistor branch, respectively; the output terminal of the first resistor branch is grounded; the output terminal of the second resistor branch is grounded through the first switching unit; the output terminal of the third resistor branch is grounded through the second switching unit; the output terminal of the optocoupler unit is connected to the input terminals of the first switching unit and the second switching unit, respectively; the controlled terminal of the optocoupler unit is connected to the control terminal of the main control unit; and the power supply terminal is connected to the input terminal of the optocoupler unit.

[0008] Furthermore, the optocoupler module includes at least an optocoupler, which includes a positive terminal for transmitting a signal, a negative terminal for transmitting a signal, a positive terminal for receiving a signal, and a negative terminal for receiving a signal. The positive terminal for transmitting the signal of the optocoupler is connected to the power supply terminal, and the negative terminal for transmitting the signal of the optocoupler is connected to the input terminals of the first switching unit and the second switching unit. The negative terminal for receiving the signal of the optocoupler is grounded, and the positive terminal for receiving the signal of the optocoupler is connected to the control terminal of the main control unit. Further, the first switching unit includes a switching transistor Q1, resistors R26, R33, and R35, capacitors C9 and C15, diodes D9 and D11, and a Zener diode Z3. One end of resistor R35 is connected to the negative terminal of the signal transmitting terminal, one end of resistor R33, the cathode of diode D11, and the input terminal of the second switching unit. The other end of resistor R35 is connected to one end of capacitor C9 and the ground terminal. The other end of capacitor C9 is connected to the other end of resistor R33, the anode of diode D11, and the cathode of Zener diode Z3. The anode of Zener diode Z3 is connected to the anode of diode D9. The cathode of diode D9 is connected to one end of capacitor C15, one end of resistor R6, and the control terminal of switching transistor Q1. The other end of capacitor C15 and the other end of resistor R6 are connected to the output terminal of switching transistor Q1. The output terminal of switching transistor Q1 is connected to the output terminal of the second switching unit, the output terminal of the first resistor branch, and the ground terminal. The input terminal of switching transistor Q1 is connected to the output terminal of the second resistor branch.

[0009] Furthermore, the second switching unit includes a switching transistor Q2, resistors R25 and R36, capacitor C8, and diode D10. The input terminal of the switching transistor Q2 is connected to the output terminal of the second resistor branch, and the output terminal of the switching transistor Q2 is connected to one end of resistor R25 and capacitor C8. The control terminal of the switching transistor Q2 is connected to the other end of resistor R25, the other end of capacitor C8, and the cathode of diode D10. The anode of diode D10 is connected to the negative terminal of the signal transmitting terminal, and resistor R36 is connected in parallel across diode D10.

[0010] Furthermore, the main control module is configured to send high-level signals, low-level signals, and pulse width modulation signals.

[0011] Furthermore, the switch module is configured as follows: When receiving a low-level signal from the main control module, both switch Q1 and switch Q2 are not turned on, causing the voltage divider module to form a first equivalent resistance value. When receiving the pulse width modulation signal sent by the main control module, the switch Q1 is turned on and the switch Q2 is turned off, so that the voltage divider module forms a second equivalent resistance value. When receiving a high-level signal from the main control module, both switch Q1 and switch Q2 are turned on, causing the voltage divider module to form a third equivalent resistance value.

[0012] Furthermore, the main control module is configured as follows: When the output voltage is detected to be within the first preset voltage range, a high-level signal is sent; When the output voltage is detected to be within the second preset voltage range, a pulse width modulation signal is sent. When the output voltage is detected to be within the third preset voltage range, a low-level signal is sent.

[0013] Furthermore, the switching transistors Q1 and Q2 are transistors.

[0014] On the other hand, this utility model also provides a power supply, including the voltage regulation circuit for a single-ended PFC power supply as described above.

[0015] This utility model embodiment dynamically adjusts the output voltage by changing the equivalent resistance value of the voltage divider module through the control switch module. This solves the problem of low efficiency of the subsequent circuit caused by the fixed bus voltage of the single-excited PFC power supply. It has the advantages of flexible bus voltage adjustment, optimized efficiency of the subsequent circuit and reduced standby power consumption. Attached Figure Description

[0016] To more clearly illustrate the technical embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a circuit structure block diagram of an embodiment of the present utility model; Figure 2 This is a circuit structure block diagram of another embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit principle of an embodiment of the present invention.

[0018] Figure label: 100. Feedback end; 200. Power supply end; 300. Voltage divider module; 310. First resistor branch; 320. Second resistor branch; 330. Third resistor branch; 400. Switching module; 410. Optocoupler unit; 420. First switching unit; 430. Second switching unit; 500. Main control module. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0021] To make the objectives, technical embodiments, and advantages of this utility model clearer, the technical embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. In existing technologies, single-pole PFC power supplies simplify the traditional multi-stage architecture by integrating power factor correction and quasi-resonant flyback circuits. However, the fixed primary-side output voltage causes the subsequent buck circuit to bear a large voltage difference. When multiple ports output different voltages simultaneously, the subsequent circuits deviate from their optimal operating point, resulting in a significant decrease in system efficiency and difficulty in controlling standby power loss under light load. For example, a certain model of adapter has a Buck circuit efficiency of 92% under 20V full load, but its efficiency drops sharply to 78% under 5V light load, and the fixed bus voltage of 400V leads to a step-down power loss as high as 15W.

[0022] To address the aforementioned issues, the inventors discovered that the inability of traditional single-ended circuits to dynamically adjust the primary-side output voltage is a key factor limiting energy efficiency. Analysis of multi-port load characteristic curves revealed that allowing the bus voltage to fluctuate with the target output voltage could reduce subsequent voltage drop losses by over 30%. Based on this, dynamically switching the voltage divider resistor using semiconductor switches can precisely control the feedback voltage; however, the impact of the switch's on-state on the voltage divider accuracy needs to be addressed. Ultimately, it was determined that a main control module would coordinate multiple switching units to construct a voltage divider network with programmable equivalent resistance.

[0023] Therefore, refer to Figure 1 This application proposes a voltage regulation circuit for a single-ended PFC power supply, including a feedback terminal 100, a power supply terminal 200, a voltage divider module 300, a switching module 400, and a main control module 500. The control terminal of the main control module 500 is connected to the controlled terminal of the switching module 400. The power supply terminal 200 is connected to the voltage divider module 300 through the switching module 400. The feedback terminal 100 is grounded through the voltage divider module 300. The main control module 500 is used to control the conduction state of the switch module 400. The switch module 400 is used to change the equivalent resistance value of the voltage divider module 300 in the conduction state. The feedback terminal 100 is used to receive the output voltage of the voltage divider module 300. The power supply terminal 200 provides operating voltage to the switch module 400 and the voltage divider module 300.

[0024] Among them, voltage divider module 300 refers to a voltage distribution network composed of multiple parallel resistor branches. By controlling the grounding state of different branches, the overall voltage division ratio can be changed; switch module 400 refers to a conduction control unit composed of semiconductor devices; main control module 500 refers to an integrated circuit with logic control function, which can be implemented by a microcontroller or a dedicated power management chip, and controls the state of the switch unit by outputting different level signals; power supply terminal 200 refers to a voltage node that provides isolated power to the control circuit, which can be implemented by a DC voltage source output by the auxiliary winding of a flyback transformer.

[0025] Compared with existing technologies, traditional single-ended power supplies use fixed voltage divider resistors to set the feedback voltage, which cannot dynamically adjust the bus voltage according to load requirements. This embodiment of the invention dynamically adjusts the output voltage by controlling the switch module 400 to change the equivalent resistance value of the voltage divider module 300. This solves the problem of low efficiency in subsequent circuits caused by a fixed bus voltage in single-ended PFC power supplies, and offers advantages such as flexible bus voltage adjustment, optimized efficiency of subsequent circuits, and reduced standby power consumption.

[0026] It should be noted that, in specific implementation, the main control module 500 is a circuit system that includes sensor signal acquisition and the coordinated operation of various control execution components, including an embedded processor, sensor signal input interface, device component control signal output interface, and related electronic circuits.

[0027] refer to Figure 2 This application further proposes that the switching module 400 includes an optocoupler unit 410, a first switching unit 420, and a second switching unit 430, and the voltage divider module 300 includes a first resistor branch 310, a second resistor branch 320, and a third resistor branch 330. The feedback terminal 100 is connected to the input terminals of the first resistor branch 310, the second resistor branch 320, and the third resistor branch 330, respectively. The output terminal of the first resistor branch 310 is grounded, the output terminal of the second resistor branch 320 is grounded through the first switching unit 420, and the output terminal of the third resistor branch 330 is grounded through the second switching unit 430. The output terminal of the optocoupler unit 410 is connected to the input terminals of the first switching unit 420 and the second switching unit 430, respectively. The controlled terminal of the optocoupler unit 410 is connected to the control terminal of the main control unit, and the power supply terminal 200 is connected to the input terminal of the optocoupler unit 410.

[0028] In practical implementation, when the main control module 500 sends control signals to the first switching unit 420 and the second switching unit 430 through the optocoupler unit 410, the light-emitting side of the optocoupler unit 410 converts the electrical signal into an optical signal, which is then received by the photosensitive side and drives the switching unit to operate. For example, when the first switching unit 420 is turned on, the second resistor branch 320 is short-circuited to ground, and the total resistance of the voltage divider module 300 is determined by the parallel connection of the first resistor branch 310 and the third resistor branch 330. When the second switching unit 430 is turned on, the third resistor branch 330 is connected to the voltage divider network, and the equivalent resistance is further reduced. By combining the on / off states of the two switching units, three different voltage division ratios can be formed, thereby outputting the corresponding voltage sampling value at the feedback terminal 100, providing a reference for subsequent voltage regulation.

[0029] Compared to existing technologies, traditional multi-stage converter architectures require independent PFC circuits and multiple Buck circuits, resulting in a large number of components and a fixed bus voltage. This embodiment, however, achieves dynamic adjustment of the voltage divider network resistance in a single-excited architecture through the coordinated control of the optocoupler unit 410 and the switching unit, changing the bus voltage setpoint without adding an independent PFC stage. For example, existing technologies typically use fixed resistor combinations in the voltage divider network, while this embodiment, through the dynamic connection of the resistor branches by the switching unit, allows the voltage division ratio to change with load demand, effectively reducing the voltage drop loss of the subsequent Buck circuit.

[0030] This application further proposes that the optocoupler module includes at least an optocoupler, which includes a positive terminal for transmitting a signal, a negative terminal for transmitting a signal, a positive terminal for receiving a signal, and a negative terminal for receiving a signal. The positive terminal for transmitting the signal of the optocoupler is connected to the power supply terminal 200, and the negative terminal for transmitting the signal of the optocoupler is connected to the input terminals of the first switching unit 420 and the second switching unit 430. The negative terminal for receiving the signal of the optocoupler is grounded, and the positive terminal for receiving the signal of the optocoupler is connected to the control terminal of the main control unit.

[0031] In this configuration, the positive terminal of the signal transmitting end refers to the positive terminal of the LED inside the optocoupler, which is used to receive the forward bias voltage provided by the power supply terminal 200 to drive the light-emitting device to work; the negative terminal of the signal transmitting end refers to the negative terminal of the LED inside the optocoupler, which is used to form a current loop and transmit control signals to the switching unit; the positive terminal of the signal receiving end refers to the collector terminal of the phototransistor inside the optocoupler, which is used to receive the control level signal output by the main control module 500 to trigger the photosensitive device to conduct; and the negative terminal of the signal receiving end refers to the emitter terminal of the phototransistor inside the optocoupler, which is used to establish a reference potential and form a signal receiving loop.

[0032] In practical implementation, the positive terminal of the optocoupler's signal transmitter is directly connected to the power supply terminal 200, enabling the light-emitting diode (LED) to generate a light signal under the supply voltage. The negative terminal of the signal transmitter is connected to the input terminals of the first switching unit 420 and the second switching unit 430, respectively, and the driving signal of the switching unit is adjusted by changing the current intensity flowing through the LED. The positive terminal of the optocoupler's signal receiver is connected to the control terminal of the main control unit, receiving voltage adjustment commands from the main control module 500, and converting the electrical signal into a light signal through a phototransistor before transmitting it to the switching unit. The negative terminal of the signal receiver is grounded to form a closed loop, ensuring the stability of the potential reference when the photosensitive device is operating.

[0033] This embodiment effectively reduces output voltage fluctuations caused by control signal distortion, improving the voltage regulation stability of the single-pole PFC power supply under different load conditions. Simultaneously, the compact package of the optocoupler reduces circuit board space requirements, facilitating miniaturized power adapter design.

[0034] refer to Figure 3 This application further proposes a voltage regulation circuit for a single-ended PFC power supply. The first switching unit 420 includes a switching transistor Q1, resistors R26, R33, and R35, capacitors C9 and C15, diodes D9 and D11, and a Zener diode Z3. One end of resistor R35 is connected to the negative terminal of the signal transmitter, one end of resistor R33, the cathode of diode D11, and the input terminal of the second switching unit 430. The other end of resistor R35 is connected to one end of capacitor C9 and the ground terminal. The other end of capacitor C9 is connected to resistor R36. 3. The other end, the anode of diode D11 and the cathode of Zener diode Z3, the anode of Zener diode Z3 is connected to the anode of diode D9, the cathode of diode D9 is connected to one end of capacitor C15, one end of resistor R6 and the control terminal of switch Q1, the other end of capacitor C15 and the other end of resistor R6 are connected to the output terminal of switch Q1, the output terminal of switch Q1 is connected to the output terminal of the second switching unit 430, the output terminal of the first resistor branch 310 and the ground terminal, and the input terminal of switch Q1 is connected to the output terminal of the second resistor branch 320.

[0035] Among them, the switching transistor Q1 is a semiconductor device that controls the conduction or cutoff by the control terminal voltage. Specifically, it can be implemented as a MOSFET or a transistor, and is used to control the on / off state of the second resistor branch 320 and the ground terminal. Resistors R35 and R33 are voltage divider components connected in series between the negative terminal of the signal transmitter and the ground terminal. Specifically, they can be implemented as surface mount resistors or carbon film resistors, and are used to limit the current flowing through the optocoupler unit 410 and form a voltage reference. Zener diode Z3 is a semiconductor device with reverse breakdown voltage regulation characteristics, and is used to establish a stable voltage threshold at the control terminal of the switching transistor Q1. Capacitors C9 and C15 are energy storage components connected in parallel between the resistor network and the control terminal of the switching transistor. Specifically, they can be implemented as ceramic capacitors or electrolytic capacitors, and are used to filter out high-frequency noise and slow down the switching speed.

[0036] Furthermore, the second switching unit 430 includes a switching transistor Q2, a resistor R25, a resistor R36, a capacitor C8, and a diode D10. The input terminal of the switching transistor Q2 is connected to the output terminal of the second resistor branch 320. The output terminal of the switching transistor Q2 is connected to one end of the resistor R25 and the capacitor C8. The control terminal of the switching transistor Q2 is connected to the other end of the resistor R25, the other end of the capacitor C8, and the cathode of the diode D10. The anode of the diode D10 is connected to the negative terminal of the signal transmitting terminal. The resistor R36 is connected in parallel across the diode D10.

[0037] This embodiment can dynamically adjust the equivalent resistance of the voltage divider module 300 according to the load requirements of the downstream stage, so that the primary side output voltage of the single-excited PFC power supply can be adapted to the target voltage under different fast charging protocols, thereby reducing the voltage drop loss of the downstream Buck circuit, improving the overall system efficiency and reducing the temperature rise, while avoiding the problem of high standby power consumption under light load caused by fixed bus voltage.

[0038] This application further proposes that the main control module 500 is configured to send high-level signals, low-level signals, and pulse-width modulation signals.

[0039] The high-level signal refers to an electrical signal with a voltage amplitude higher than a preset threshold. This can be implemented using a logic high level or a specific voltage value, and is used to trigger the switch module 400 to enter the on state. The low-level signal refers to an electrical signal with a voltage amplitude lower than a preset threshold. This can be implemented using a logic low level or a ground level, and is used to maintain the switch module 400 in the off state. The pulse width modulation signal refers to a periodic pulse signal with an adjustable duty cycle. This can be generated using a microcontroller or a dedicated chip, and is used to control the equivalent on time of the switch module 400 by adjusting the duty cycle.

[0040] Specifically, the main control module 500 changes the conduction state of the switching module 400 by outputting different control signals. When a low-level signal is output, all switches in the switching module 400 are turned off, the equivalent resistance of the voltage divider module 300 reaches its maximum value, and the feedback terminal 100 detects the highest voltage value. When a pulse width modulation signal is output, some switches in the switching module 400 are periodically turned on, the equivalent resistance of the voltage divider module 300 changes dynamically with the duty cycle, and the voltage at the feedback terminal 100 is adjusted accordingly. When a high-level signal is output, all switches in the switching module 400 are fully turned on, the equivalent resistance of the voltage divider module 300 drops to its minimum value, and the voltage at the feedback terminal 100 corresponds to the lowest value. Thus, the main control module 500 achieves multi-level adjustment of the equivalent resistance of the voltage divider module 300 by switching between three signal modes, thereby controlling the output voltage of the single-ended PFC power supply.

[0041] This embodiment solves the problem of limited efficiency of subsequent stages caused by the fixed output voltage of a single-excitation PFC power supply. By dynamically adjusting the bus voltage to make it closer to the target value, the energy loss during the buck conversion process is reduced. At the same time, the standby power consumption under light load conditions is optimized, thereby improving the overall energy efficiency of the system.

[0042] This application further proposes that the switching module 400 is configured such that when it receives a low-level signal sent by the main control module 500, both switching transistors Q1 and Q2 are not turned on, causing the voltage divider module 300 to form a first equivalent resistance value; when it receives a pulse width modulation signal sent by the main control module 500, switching transistor Q1 is turned on and switching transistor Q2 is not turned on, causing the voltage divider module 300 to form a second equivalent resistance value; and when it receives a high-level signal sent by the main control module 500, both switching transistors Q1 and Q2 are turned on, causing the voltage divider module 300 to form a third equivalent resistance value.

[0043] In this context, a low-level signal refers to a control signal with a voltage lower than the switching threshold of the transistor, specifically implemented using a 0V or near-0V voltage signal, used to keep the transistor in the off state. A pulse-width modulation (PWM) signal refers to a periodic pulse signal, specifically implemented using a square wave signal with a variable duty cycle, controlling the on-time ratio of the transistor by adjusting the duty cycle. A high-level signal refers to a continuous signal with a voltage higher than the switching threshold of the transistor, specifically implemented using a constant positive voltage signal, used to maintain the transistor in continuous conduction. The equivalent resistance value refers to the total resistance value presented by multiple resistor branches connected in parallel or disconnected in the voltage divider network, specifically adjusted by changing the number of parallel resistors by controlling the on / off state of the transistor, thereby adjusting the voltage division ratio.

[0044] Specifically, when the main control module 500 outputs a low-level signal, no current flows through the optocoupler unit 410, and the switching transistors Q1 and Q2 in the first switching unit 420 and the second switching unit 430 are both off. At this time, the second resistor branch 320 and the third resistor branch 330 are disconnected from ground, and the voltage divider module 300 forms a voltage divider only through the first resistor branch 310, generating a first equivalent resistance value. When the main control module 500 outputs a pulse width modulation signal, the optocoupler unit 410 is intermittently turned on according to the signal duty cycle, driving the switching transistor Q1 to periodically turn on while Q2 remains off. At this time, the second resistor branch 320 is intermittently connected to the voltage divider network, and the equivalent resistance value changes proportionally with the on-time to form a second equivalent resistance value. When the main control module 500 outputs a high-level signal, the optocoupler unit 410 is continuously turned on, simultaneously triggering Q1 and Q2 to turn on. The second resistor branch 320 and the third resistor branch 330 are both connected to the voltage divider network, forming a third equivalent resistance value. The voltage divider detected by the feedback terminal 100 changes with the equivalent resistance, thereby adjusting the primary bus voltage level.

[0045] This embodiment enables multi-level adjustment of the primary-side output voltage within a single-ended integrated architecture, significantly reducing the voltage difference between the bus voltage and the target voltage of the subsequent stage. This reduces the voltage drop losses in the subsequent Buck circuit while avoiding the size and cost issues associated with adding a separate PFC stage. Through a switching mechanism of the equivalent resistance value of the voltage divider network, this embodiment effectively balances the requirements of high-efficiency conversion for multi-port outputs and low standby power consumption while maintaining a simplified single-ended structure.

[0046] In one embodiment, the main control module 500 is further configured to switch the operating state of the switching module 400 according to different output voltage levels. Specifically, the main control module 500 is configured to: send a high-level signal when the output voltage is detected to be within a first preset voltage range; send a pulse width modulation signal when the output voltage is detected to be within a second preset voltage range; and send a low-level signal when the output voltage is detected to be within a third preset voltage range. Through the above control method, the switching module 400 achieves corresponding conduction states under the action of different control signals, thereby changing the equivalent resistance value of the voltage divider module 300 and realizing multi-level voltage switching at the power supply output terminal.

[0047] It should be noted that the high-level signal, low-level signal, and pulse width modulation signal output by the main control module 500 in this embodiment are conventional control signal types that can be implemented by those skilled in the art without creative effort. However, combining these control signals with the connection structure of the voltage divider module 300, the switch module 400, and the feedback terminal 100 in this embodiment, and using the conduction state corresponding to different control signals to change the equivalent resistance value of the voltage divider module 300, thereby realizing multi-level adjustable output voltage of the primary side of the single-excited PFC power supply, requires structural improvement and matching design of the feedback loop of the existing single-excited PFC power supply. Those skilled in the art cannot directly derive this without creative effort, and therefore it should be considered as one of the creative improvements of this utility model.

[0048] In one embodiment, the first preset voltage range is 15V to 20V, the second preset voltage range is 9V to 12V, and the third preset voltage range is 4.5V to 5.5V.

[0049] It should also be noted that the main control module 500 is used to detect the output voltage and determine its position within a preset voltage range, which is a conventional technique in the art. For example, the main control module 500 can sample the voltage at the power supply output terminal in real time through its built-in analog-to-digital converter (ADC) and compare the sampling result with a preset voltage threshold to determine whether the current output voltage is within a first, second, or third preset voltage range, and output a corresponding control signal accordingly. Since the above-mentioned voltage sampling and threshold comparison control technology is well known to those skilled in the art, its specific structure and control process will not be described in detail in this embodiment.

[0050] Furthermore, in this embodiment, the switching transistors Q1 and Q2 in the switching module 400 are transistor devices, specifically metal-oxide-semiconductor field-effect transistors, used to turn on or off under the control signal of the main control module 500, so as to control the on / off state between the second resistor branch 320 and the ground terminal.

[0051] Reference Figure 3 The working principle of this embodiment is as follows: When the required output voltage is within the first preset voltage range, the main control module 500 outputs a high-level signal. After being fully turned on by the optocoupler unit 410, it simultaneously drives the first switching unit 420 and the second switching unit 430 to turn on. The power supply terminal 200 charges capacitor C8 through diode D10, thus providing a high-level drive for Q7; the power supply terminal 200 also charges capacitor C15 through resistor R33 and Zener diode Z3, thus providing a high-level drive for Q8. At this time, the lower bias resistor in the voltage divider module 300 is composed of resistors R24, R27, and R40 connected in parallel, resulting in the minimum equivalent resistance, which increases the voltage at the Vsense feedback terminal 100.

[0052] When the required output voltage is within the second preset voltage range, the main control module 500 outputs a pulse width modulation signal with a frequency of 1kHz and a duty cycle of 50%. This signal, driven by the optocoupler unit 410, turns on the first switching unit 420 and keeps the second switching unit 430 off. During the PWM high-level period, the power supply terminal 200 charges capacitor C8 through diode D10, and discharges it through resistors R36 and R35 during the low-level period. Because the charge amount is greater than the discharge amount, it provides a continuous high-level drive for Q7. Simultaneously, during the PWM high-level period, the power supply terminal 200 charges capacitor C9 through resistor R33, and discharges it through diode D11 and resistor R35 during the low-level period. Because the discharge amount is greater than the charge amount and the voltage of capacitor C9 is lower than the conduction threshold of the Zener diode Z3, the second switching unit 430Q8 remains off. At this time, the lower bias resistor in the voltage divider module 300 is composed of resistors R24 and R27 connected in parallel.

[0053] When the required output voltage is within the third preset voltage range, the main control module 500 outputs a low-level signal, which completely cuts off the optocoupler unit 410. The first switch unit 420 and the second switch unit 430 are not turned on, and their control terminals are both in a low-level state. At this time, the lower bias resistor in the voltage divider module 300 is only resistor R24.

[0054] It should be noted that since Z3 only conducts when the voltage across it is higher than 5.1V, when the voltage of C9 is lower than this threshold, Z3 remains in the off state and cannot provide drive voltage to the control terminal of the second switching unit 430Q8, thus Q8 remains non-conducting. In this way, when the main control module 500 outputs a pulse width modulation signal, only the first switching unit 420Q7 is driven to conduct, while the second switching unit 430Q8 remains in the off state, achieving the equivalent resistance of the voltage divider module 300 at the middle level, thereby outputting the second voltage level. Those skilled in the art will understand that the parameters of R33, capacitor C9, resistor R35, and diode D11 can be adjusted according to the PWM frequency and duty cycle to ensure that the voltage of C9 is always lower than the conduction threshold of Z3, preventing Q8 from being mis-conducted due to voltage rise.

[0055] This application further proposes a power supply including a voltage regulation circuit for a single-stage PFC power supply. Compared with the efficiency loss caused by the fixed bus voltage in the three-stage architecture, this embodiment achieves adjustable bus voltage in a single-stage integrated architecture, avoiding the size and loss problems caused by multi-stage transformation.

[0056] The above description is only used to illustrate the technical embodiments of this utility model and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical embodiments of this utility model, as long as they do not depart from the spirit and scope of the technical embodiments of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A voltage regulating circuit for a single-switch PFC power supply, characterized by, It includes a feedback terminal (100), a power supply terminal (200), a voltage divider module (300), a switch module (400), and a main control module (500). The control terminal of the main control module (500) is connected to the controlled terminal of the switch module (400). The power supply terminal (200) is connected to the voltage divider module (300) through the switch module (400). The feedback terminal (100) is grounded through the voltage divider module (300). The main control module (500) is used to control the conduction state of the switch module (400). The switch module (400) is used to change the equivalent resistance value of the voltage divider module (300) in the conduction state. The feedback terminal (100) is used to receive the output voltage of the voltage divider module (300). The power supply terminal (200) provides the working voltage to the switch module (400) and the voltage divider module (300).

2. The voltage regulation circuit for a single inverter PFC power supply of claim 1, wherein, The switching module (400) includes an optocoupler unit (410), a first switching unit (420), and a second switching unit (430). The voltage divider module (300) includes a first resistor branch (310), a second resistor branch (320), and a third resistor branch (330). The feedback terminal (100) is connected to the input terminals of the first resistor branch (310), the second resistor branch (320), and the third resistor branch (330), respectively. The output terminal of the first resistor branch (310) is grounded. The output terminal of the second resistor branch (320) is grounded through the first switch unit (420), the output terminal of the third resistor branch (330) is grounded through the second switch unit (430), the output terminal of the optocoupler unit (410) is connected to the input terminals of the first switch unit (420) and the second switch unit (430) respectively, the controlled terminal of the optocoupler unit (410) is connected to the control terminal of the main control module, and the power supply terminal (200) is connected to the input terminal of the optocoupler unit (410).

3. The voltage regulation circuit for a single inductor PFC power supply of claim 2, wherein, The optocoupler unit includes at least an optocoupler, which includes a positive terminal for transmitting a signal, a negative terminal for transmitting a signal, a positive terminal for receiving a signal, and a negative terminal for receiving a signal. The positive terminal for transmitting a signal is connected to the power supply terminal (200), and the negative terminal for transmitting a signal is connected to the input terminals of the first switching unit (420) and the second switching unit (430). The negative terminal for receiving a signal is grounded, and the positive terminal for receiving a signal is connected to the control terminal of the main control module.

4. The voltage regulation circuit for a single inductor PFC power supply of claim 3, wherein, The first switching unit (420) includes a switching transistor Q1, resistors R26, R33, and R35, capacitors C9 and C15, diodes D9 and D11, and a Zener diode Z3. One end of resistor R35 is connected to the negative terminal of the signal transmitter, one end of resistor R33, the cathode of diode D11, and the input terminal of the second switching unit (430). The other end of resistor R35 is connected to one end of capacitor C9 and the ground terminal. The other end of capacitor C9 is connected to the other end of resistor R33, the anode of diode D11, and the Zener diode Z3. The cathode of diode Z3 is connected to the anode of diode D9. The cathode of diode D9 is connected to one end of capacitor C15, one end of resistor R6, and the control terminal of switch Q1. The other end of capacitor C15 and the other end of resistor R6 are connected to the output terminal of switch Q1. The output terminal of switch Q1 is connected to the output terminal of the second switching unit (430), the output terminal of the first resistor branch (310), and the ground terminal. The input terminal of switch Q1 is connected to the output terminal of the second resistor branch (320).

5. The voltage regulation circuit for a single inductor PFC power supply of claim 4, wherein, The second switching unit (430) includes a switching transistor Q2, a resistor R25, a resistor R36, a capacitor C8, and a diode D10. The input terminal of the switching transistor Q2 is connected to the output terminal of the second resistor branch (320). The output terminal of the switching transistor Q2 is connected to one end of the resistor R25 and the capacitor C8. The control terminal of the switching transistor Q2 is connected to the other end of the resistor R25, the other end of the capacitor C8, and the cathode of the diode D10. The anode of the diode D10 is connected to the negative terminal of the signal transmitting terminal. The resistor R36 is connected in parallel across the diode D10.

6. The voltage regulation circuit for a single inductor PFC power supply of claim 5, wherein, The main control module (500) is configured to send high-level signals, low-level signals, and pulse width modulation signals.

7. The voltage regulation circuit for a single inductor PFC power supply of claim 6, wherein, The switch module (400) is configured to: When receiving a low-level signal sent by the main control module (500), both switch transistors Q1 and Q2 are not turned on, so that the voltage divider module (300) forms a first equivalent resistance value; When receiving the pulse width modulation signal sent by the main control module (500), the switch Q1 is turned on and the switch Q2 is not turned on, so that the voltage divider module (300) forms a second equivalent resistance value. When receiving a high-level signal sent by the main control module (500), both switch transistors Q1 and Q2 are turned on, causing the voltage divider module (300) to form a third equivalent resistance value.

8. The voltage regulation circuit for a single inductor PFC power supply of claim 7, wherein, The main control module (500) is configured as follows: When the output voltage is detected to be within the first preset voltage range, a high-level signal is sent; When the output voltage is detected to be within the second preset voltage range, a pulse width modulation signal is sent. When the output voltage is detected to be within the third preset voltage range, a low-level signal is sent.

9. The voltage regulation circuit for a single inductor PFC power supply of claim 5, wherein, The switching transistors Q1 and Q2 are transistors.

10. A power supply, characterized by, Includes a voltage regulation circuit for a single-ended PFC power supply as described in any one of claims 1-9.

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