Multipath output switching power supply sharing rectification

Abstract

The utility model discloses a multi-output switching power supply sharing rectification, which consists of a lightning protection unit, an EMI (Electro-Magnetic Interference) circuit, a public rectification filter circuit, a plurality of independent output circuits and a plurality of output ends, and each independent output circuit comprises a power conversion module, an independent rectification filter module, a PWM (Pulse-Width Modulation) controller and a sampling voltage stabilizing circuit, an external alternating current power supply firstly suppresses lightning stroke surge through the lightning protection unit, then filters electromagnetic interference through the EMI circuit, then enters the public rectification filter circuit to be converted into direct current and is filtered for the first time, and then high-frequency alternating current conversion, secondary rectification filter and voltage stabilization adjustment are carried out through the multiple independent output circuits. And finally, stable and accurate voltage is output through a multi-path output end. According to the utility model, through separation of common rectification filtering and multipath output rectification filtering and combination of functions of lightning protection, interference resistance and the like, independent and accurate adjustment of multipath output voltage is realized, power supply conversion efficiency is improved, cost and size are reduced, and stability and reliability of the power supply are enhanced.

Description

Technical Field

[0001] This utility model relates to the field of power supply circuits, and in particular to a multi-output switching power supply with shared rectification. Background Technology

[0002] In modern electronic devices, the demands on power supplies are increasingly stringent. Power supplies require not only multiple voltage outputs but also high stability, high conversion efficiency, and strong anti-interference capabilities. Traditional multi-output switching power supplies suffer from several problems. Some power supplies equip each output with an independent, complete circuit, resulting in a large number of components, significantly increased costs, and a large board space requirement, hindering device miniaturization and integration. Other designs using shared circuitry fail to effectively separate the common rectification and filtering from the rectification and filtering of the multiple outputs, leading to mutual interference between outputs and making it impossible to achieve high-precision voltage output control. This makes it difficult to meet the high-precision power supply requirements of devices such as precision instruments and communication equipment. Furthermore, traditional power supplies lack sufficient protection against lightning surges and electromagnetic interference, easily leading to circuit failures and affecting normal equipment operation. For example, in communication base stations, various devices require different voltage power supplies; traditional power supplies cannot provide stable power and often fail due to lightning strikes and electromagnetic interference, affecting communication quality. Therefore, developing a switching power supply that can solve these problems is of great significance. Utility Model Content

[0003] Based on this, the purpose of this utility model is to provide a multi-output switching power supply with a shared rectifier. By separating the common rectifier filter and the multi-output rectifier filter, and combining functions such as lightning protection and anti-interference, it can realize independent and precise adjustment of the multi-output voltage, improve power conversion efficiency, reduce cost and size, and enhance the stability and reliability of the power supply.

[0004] The objective of this utility model is achieved through the following technical solution:

[0005] A multi-output switching power supply with shared rectification comprises a surge protection unit, an EMI circuit, a common rectifier and filter circuit, multiple independent output circuits, and multiple output terminals. External AC power first passes through the surge protection unit to suppress lightning surges, then through the EMI circuit to filter out electromagnetic interference. Next, it enters the common rectifier and filter circuit to be converted to DC and initially filtered. Then, the multiple independent output circuits perform high-frequency AC conversion, secondary rectification and filtering, and voltage regulation, finally outputting a stable and precise voltage through the multiple output terminals. A PWM controller coordinates the operation of each component to ensure stable output.

[0006] Lightning protection unit: The lightning protection unit includes at least one of the following: varistor, gas discharge tube, and thermistor. The varistor is connected between the live wire and neutral wire, live wire and ground wire, and neutral wire and ground wire. When the surge voltage generated by a lightning strike exceeds its conduction voltage, the varistor quickly conducts, clamping the excessive voltage and protecting subsequent circuits. The gas discharge tube is connected between the live wire or neutral wire and ground wire, rapidly discharging under high voltage to release lightning energy. The thermistor is connected in series in the power input circuit. When the circuit current rises due to excessive lightning surge, its resistance increases, limiting the current and preventing circuit components from being damaged by overheating.

[0007] The nominal voltage range of the varistor is 100V-1000V, the DC breakdown voltage range of the gas discharge tube is 150V-800V, and the resistance of the thermistor is 5Ω-50Ω at room temperature.

[0008] EMI Circuit: The filter network consists of a first common-mode inductor, a differential-mode inductor, and a first capacitor. The first common-mode inductor is connected in series in the circuit to suppress common-mode interference between the two power lines and ground; the differential-mode inductor is connected in series between the live wire and the neutral wire to suppress differential-mode interference between the two power lines; the first capacitor is connected between the live wire and ground, the neutral wire and ground, and the live wire and the neutral wire respectively to further filter out residual high-frequency interference signals and ensure the purity of the power output.

[0009] The common-mode inductor has an inductance range of 0.5mH-5mH, the differential-mode inductor has an inductance range of 50μH-500μH, and the first capacitor has a capacitance range of 0.01μF-10μF.

[0010] The common rectifier and filter circuit includes a rectifier bridge, a second capacitor, and a second common-mode inductor. The rectifier bridge converts AC power into pulsating DC power. The second capacitor, with a capacitance value between 100μF and 1000μF, is connected in parallel to the DC output of the rectifier bridge. Its charging and discharging action filters out low-frequency ripple, making the output DC power smoother. The second common-mode inductor, with an inductance value between 0.5mH and 2mH, is connected in series between the second capacitor and the power conversion module. It suppresses common-mode interference and provides a stable DC input to the power conversion module.

[0011] Multi-channel independent output circuit: Each includes a power conversion module, an independent rectification and filtering module, a PWM controller and a sampling and voltage regulation circuit. The multi-channel independent output circuit includes at least two outputs, each of which is independent of the others. The output voltage range is 1V-50V, the output current range is 0.5A-10A, and the output ripple voltage is ≤50mVrms.

[0012] Power Conversion Module: The power conversion module mainly consists of a switching transistor and a transformer. The switching transistor is turned on and off under the control of the PWM controller. When the switching transistor is on, current flows through the primary winding of the transformer, storing energy. When the switching transistor is off, the current in the primary winding changes rapidly, generating an induced electromotive force in the secondary winding of the transformer, and outputting an AC voltage.

[0013] The rectifier diodes in the independent rectifier and filter module convert the high-frequency AC power output from the power conversion module into DC power. Then, the DC power is filtered again by a third capacitor connected in parallel with the output of the rectifier diodes to remove high-frequency ripple, thereby further reducing the output DC ripple.

[0014] The sampling resistor group in the sampling voltage regulator circuit samples the voltage output from the independent rectifier and filter module. The accuracy of the sampling resistors is no less than 1%, the open-loop gain of the operational amplifier is no less than 80dB, and the accuracy of the reference voltage source is no less than 0.5%. The sampled voltage signal is input to one input terminal of the operational amplifier, and the other input terminal is connected to the reference voltage. The operational amplifier compares the sampled voltage with the reference voltage and outputs an error signal. This error signal is transmitted to the PWM controller through a feedback circuit. The PWM controller adjusts the on and off times of the switching transistors in the power conversion module according to the error signal, thereby regulating the output voltage and achieving stable regulation of the output voltage.

[0015] Multiple output terminals: Connected one-to-one with multiple independent output circuits to output multiple stable and accurate voltages to meet the power supply needs of different electronic devices.

[0016] The beneficial effects of this utility model are:

[0017] Cost and size optimization: By sharing the common rectifier filter circuit and the front-end section of the power conversion module, the number of components is reduced. The sharing of common circuits reduces costs, shrinks the board space occupied, and enables power supply miniaturization.

[0018] Precise and stable output: Each output has an independent rectification, filtering and sampling voltage regulation circuit, which can achieve precise control of the output voltage of each output, effectively reduce mutual interference between outputs, ensure the stability and accuracy of the output voltage, and meet the needs of electronic equipment with high power supply accuracy requirements. Attached Figure Description

[0019] Figure 1 Block diagram of a switching power supply circuit. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1 As shown, this embodiment provides a switching power supply circuit with two outputs (output 1 is 5V, output 2 is 12V), including:

[0022] The surge protection unit is connected to the external AC power input side to suppress damage to the circuit caused by lightning surges.

[0023] An EMI circuit, the input of which is connected to the output of the surge protection unit, is used to filter out electromagnetic interference on the power line.

[0024] A common rectifier and filter circuit is provided, wherein the input terminal of the common rectifier and filter circuit is connected to the output terminal of the EMI circuit, and is used to convert AC power into DC power and perform initial filtering.

[0025] Two independent output circuits, each of which includes a power conversion module, an independent rectification and filtering module, a PWM controller, and a sampling and voltage regulation circuit;

[0026] The input terminal of the power conversion module is connected to the output terminal of the common rectifier and filter module, and is used to convert DC power into high-frequency AC power.

[0027] The output terminal of the power conversion module is connected to the input terminal of the independent rectifier and filter module, which is used to convert high-frequency AC power into DC power and filter it again.

[0028] The sampling and voltage regulation circuit is connected to the output terminals of the PWM controller and the independent rectifier and filter module, respectively, and is used to sample and stabilize the output voltage.

[0029] The PWM controller is connected to the power conversion module and the sampling voltage regulator circuit respectively. It is used to sample the output voltage and feed it back to the PWM controller. The PWM controller controls the working state of the power conversion module according to the feedback signal to achieve stable and precise adjustment of the multi-channel output voltage.

[0030] The two output terminals are connected one-to-one with the two independent output circuits to output multiple stable and accurate voltages.

[0031] The surge protection unit utilizes a MYG14K471 varistor with a nominal voltage of 470V, connected between the live and neutral wires, the live and ground wires, and the neutral and ground wires. A GDT10L330 gas discharge tube with a DC breakdown voltage of 330V is connected between the live and ground wires. An NTC10D-11 thermistor with a room temperature resistance of 10Ω is connected in series with the power input live wire. When a lightning surge occurs, the varistor quickly conducts, dissipating the excessive voltage; the gas discharge tube rapidly discharges energy; and the thermistor's resistance increases during overcurrent, limiting the current and protecting subsequent circuitry.

[0032] EMI Circuit: The first common-mode inductor is a CDRH10D12-1000 with an inductance of 1mH, connected in series in the circuit; the differential-mode inductor is a CDRH5D7-100 with an inductance of 100μF, connected in series between the live and neutral wires; the first capacitor C1 is a 0.1μF ceramic capacitor connected between the live and ground wires, the first capacitor C2 is a 0.1μF ceramic capacitor connected between the neutral and ground wires, and the first capacitor C3 is a 0.01μF ceramic capacitor connected between the live and neutral wires. This filter network effectively filters out common-mode and differential-mode interference on the power lines, ensuring a clean power signal input to the common rectifier filter circuit.

[0033] Common rectifier and filter circuit: The rectifier bridge uses a KBPC3510 rectifier bridge stack, which can withstand large current and voltage, converting AC power into pulsating DC power; the second capacitor is a 470μF / 400V electrolytic capacitor, connected in parallel at the DC output terminal of the rectifier bridge to filter out low-frequency ripple; the second common-mode inductor is a CDRH10D12-1000 with an inductance of 1mH, connected in series between the second capacitor and the power conversion modules in each independent output circuit to suppress common-mode interference.

[0034] Independent output circuit - Output 1 (5V):

[0035] Power conversion module: The switching transistor is an IRF840 MOSFET, which has low on-resistance and fast switching speed. The transformer is an EE25 type, with 100 turns in the primary winding and 10 turns in the secondary winding, to output a high-frequency AC voltage suitable for 5V output.

[0036] Independent rectifier and filter module: The rectifier diode is a 1N5819 Schottky diode, which has a low forward voltage drop and low conduction loss, making it suitable for low-voltage output rectification. The third capacitor consists of a 1000μF electrolytic capacitor with a voltage rating of 16V and a 0.1μF ceramic capacitor with a voltage rating of 50V connected in parallel. The electrolytic capacitor is used to filter out low-frequency ripple, and the ceramic capacitor is used to filter out high-frequency ripple.

[0037] Sampling and voltage regulation circuit: The sampling resistor group consists of two resistors, R1 is a 4.7kΩ precision resistor, and R2 is a 1kΩ precision resistor. The output voltage is sampled through a voltage divider. A dual operational amplifier (LM358) is used, with one operational amplifier used for voltage comparison in this circuit. An adjustable reference voltage source (TL431) with an output reference voltage of 2.5V is used. The sampled voltage, after being divided by R1 and R2, is input to the non-inverting input of the LM358. The 2.5V reference voltage output from the TL431 is input to the inverting input of the LM358. The error signal output by the LM358 after comparison is fed back to the PWM controller through a resistor.

[0038] Independent output circuit - Output 2 (12V):

[0039] Power conversion module: The switching transistor is also an IRF840 MOSFET. The primary winding of the transformer has 100 turns and the secondary winding has 24 turns to output a high-frequency AC voltage suitable for 12V output.

[0040] Independent rectifier and filter module: The rectifier diode is a standard 1N4007 model, which has a high voltage rating and can meet the 12V output requirement. The third capacitor consists of a 2200μF / 25V electrolytic capacitor and a 0.1μF / 50V ceramic capacitor connected in parallel to filter out ripple.

[0041] Sampling and voltage regulation circuit: The sampling resistor group consists of R3 and R4, where R3 is a 10kΩ precision resistor and R4 is a 2.2kΩ precision resistor. The operational amplifier is also an LM358, and the reference voltage source remains a TL431. The sampled voltage, after being divided by R3 and R4, is compared with the 2.5V reference voltage output from the TL431 in the LM358, and the output error signal is fed back to the PWM controller.

[0042] PWM Controller: A UC3842 PWM control chip is selected. It can precisely control the on and off times of the switching transistors based on the error signal fed back from the sampling voltage regulator circuit, thereby achieving stable regulation of the output voltage. The operating frequency of the UC3842 can be adjusted using external resistors and capacitors. In this embodiment, its operating frequency is set to 50kHz.

[0043] Multiple output terminals: Output terminal 1 outputs a stable 5V voltage, and output terminal 2 outputs a stable 12V voltage, which can power different electronic devices. For example, 5V can be used to power a microcontroller, and 12V can be used to power certain sensors or actuators.

[0044] As can be seen from the above embodiments, the multi-output switching power supply circuit with a shared preamplifier of this utility model can achieve multiple independent and precise outputs, and has significant advantages in improving conversion efficiency, reducing cost and size, and can meet the power needs of various electronic devices.

[0045] The above description merely illustrates the preferred technical solution of this utility model, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and this utility model also intends to include these modifications and variations.

Claims

1. A multi-output switching power supply with a shared rectifier, characterized in that: include: The surge protection unit is connected to the external AC power input side to suppress damage to the circuit caused by lightning surges. An EMI circuit, the input of which is connected to the output of the surge protection unit, is used to filter out electromagnetic interference on the power line. A common rectifier and filter circuit is provided, wherein the input terminal of the common rectifier and filter circuit is connected to the output terminal of the EMI circuit, and is used to convert AC power into DC power and perform initial filtering. The multi-channel independent output circuit includes a power conversion module, an independent rectification and filtering module, a PWM controller, and a sampling and voltage regulation circuit. The input terminal of the power conversion module is connected to the output terminal of the common rectifier and filter module, and is used to convert DC power into high-frequency AC power. The output terminal of the power conversion module is connected to the input terminal of the independent rectifier and filter module, which is used to convert high-frequency AC power into DC power and filter it again. The sampling and voltage regulation circuit is connected to the output terminals of the PWM controller and the independent rectifier and filter module, respectively, and is used to sample and stabilize the output voltage. The PWM controller is connected to both the power conversion module and the sampling voltage regulator circuit, and is used to sample the output voltage and feed it back to the PWM controller.

2. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The lightning protection unit includes at least one of a varistor, a gas discharge tube, and a thermistor. The varistor is connected between the live wire and the neutral wire, the live wire and the ground wire, and the neutral wire and the ground wire. The gas discharge tube is connected between the live wire or the neutral wire and the ground wire. The thermistor is connected in series in the power input line.

3. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The EMI circuit includes a filter network consisting of a first common-mode inductor, a differential-mode inductor, and a first capacitor. The first common-mode inductor is connected in series in the circuit, the differential-mode inductor is connected in series between the live wire and the neutral wire, and the first capacitor is connected between the live wire and the ground wire, the neutral wire and the ground wire, and the live wire and the neutral wire, respectively.

4. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The common rectifier filter circuit includes: The rectifier bridge, whose input terminal is connected to the output terminal of the EMI circuit, is used to convert the input AC power into pulsating DC power. The second capacitor is connected in parallel to the DC output terminal of the rectifier bridge to filter out low-frequency ripple in the pulsating DC current. The second common-mode inductor has one end connected to the second capacitor and the other end connected to the power conversion module in the multi-channel independent output circuit, which is used to suppress common-mode interference.

5. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The power conversion module includes: The switching transistor performs turn-on and turn-off actions under the control of the PWM controller; A transformer, the primary winding of which is connected to the switching transistor, generates alternating current in the primary winding of the transformer when the switching transistor is turned on and off.

6. The multi-output switching power supply with shared rectification according to claim 5, characterized in that: The independent rectifier and filter module includes: A rectifier diode is used to convert the input alternating current (AC) into direct current (DC). The third capacitor is connected in parallel to the output terminal of the rectifier diode.

7. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The sampling voltage regulator circuit includes: A sampling resistor group is used to sample the voltage output by the independent rectifier and filter module; An operational amplifier has one input terminal connected to the sampling output of the sampling resistor group and the other input terminal connected to a reference voltage, used to compare the sampled voltage and the reference voltage and output an error signal; A feedback circuit, connected between the output of the operational amplifier and the PWM controller, is used to feed back the error signal to the PWM controller.

8. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: The multi-channel independent output circuit includes at least two outputs, each of which is independent of the others. The output voltage range is 1V-50V, the output current range is 0.5A-10A, and the output ripple voltage is ≤50mVrms.

9. The multi-output switching power supply with shared rectification according to claim 1, characterized in that: It also includes multiple output terminals, which are connected one-to-one with the multiple independent output circuits to output multiple stable and accurate voltages.

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