技术领域technical field
本发明涉及一种开关电源，具体涉及一种多路输出单端反激式开关电源。The invention relates to a switching power supply, in particular to a multi-channel output single-end flyback switching power supply.
背景技术Background technique
电力电子设备与人们的生活、工作密切相关，而这些设备都需要可靠的电源供电。传统的线性电源工作在放大状态，工作频率为50HZ，所用变压器的体积大，因此线性电源的体积大，重量大，供耗大，发热量高，效率低，携带困难。而开关电源工作在饱和状态和截止状态，即开关状态，工作频率为50KHZ，所用变压器的体积小。所以开关电源重量轻、体积小、发热量低、效率高、性能稳定、使用方便，在通信、航天、仪器、设备、机械、电器等多种领域中被广泛应用。Power electronic devices are closely related to people's life and work, and these devices require reliable power supply. The traditional linear power supply works in the amplified state, the working frequency is 50HZ, and the volume of the transformer used is large. Therefore, the linear power supply is large in size, heavy in weight, large in supply and consumption, high in heat generation, low in efficiency, and difficult to carry. The switching power supply works in the saturation state and the cut-off state, that is, the switching state, the operating frequency is 50KHZ, and the volume of the transformer used is small. Therefore, switching power supplies are light in weight, small in size, low in heat generation, high in efficiency, stable in performance, and easy to use, and are widely used in various fields such as communications, aerospace, instruments, equipment, machinery, and electrical appliances.
发明内容Contents of the invention
本发明是为了解决上述问题而进行的，目的在于提供一种多路输出单端反激式开关电源。The present invention is made to solve the above problems, and aims to provide a multi-output single-ended flyback switching power supply.
本发明提供了一种多路输出单端反激式开关电源，用于将输入的交流电转变为预定电压的输出直流电并进行输出，具有这样的特征，包括：输入整流滤波电路，用于将输入的交流电变换成直流电通过+V0端口输出；DC-DC变换电路，用于降低直流电的电压从而形成低的直流电压，包括用于将直流电压逆变为高频变压器作用的交流电压的逆变电路和用于将输出电压的纹波变得更为平滑的输出整流滤波电路；UC3844控制电路，用于产生不同脉宽的PWM信号来驱动全控MOSFET开关管；以及反馈电路，用于从输出的电压采样得到误差电压，经过误差放大后输入到UC3844控制电路来控制占空比，从而稳定输出电压，其中，逆变电路包括连接于+V0端口的电容C6、与电容C6连接的电阻R1、与电阻R1连接的电容C7、与电容C7连接的电阻R2及与电阻R2连接的二极管D8和高频变压器，UC3844控制电路包括UC3844控制芯片和稳压管D11，与控制芯片第一管脚连接的电阻R7和电容C11、与控制芯片第二管脚连接的R15、与控制芯片第三管脚连接的电容C10和电阻R4、与电阻R4连接的二极管D10、与二极管D10连接的电容C9和电阻R3，连接于控制芯片第四管脚与第八管脚之间的电阻R14，与第四管脚连接的电容C19，与控制芯片第六管脚连接的电阻R6、与电阻R6连接的全控MOSFET开关管S、与全控MOSFET开关管S连接的电阻R5、与控制芯片第八管脚连接的电容C12以及与稳压管D11连接的极性电容C8和二极管D9。The present invention provides a multi-output single-ended flyback switching power supply, which is used to convert the input AC power into an output DC power of a predetermined voltage and output it. The alternating current is converted into direct current and output through the +V0 port; the DC-DC conversion circuit is used to reduce the voltage of the direct current to form a low direct current voltage, including an inverter circuit for inverting the direct current voltage into the alternating voltage of the high frequency transformer And the output rectification and filtering circuit used to smooth the ripple of the output voltage; the UC3844 control circuit is used to generate PWM signals with different pulse widths to drive the fully-controlled MOSFET switch tube; and the feedback circuit is used for output from The error voltage is obtained by voltage sampling, and after error amplification, it is input to the UC3844 control circuit to control the duty cycle, thereby stabilizing the output voltage. Among them, the inverter circuit includes a capacitor C6 connected to the +V0 port, a resistor R1 connected to the capacitor C6, and The capacitor C7 connected to the resistor R1, the resistor R2 connected to the capacitor C7, the diode D8 connected to the resistor R2 and the high-frequency transformer, the UC3844 control circuit includes the UC3844 control chip and the regulator tube D11, and the resistor connected to the first pin of the control chip R7 and capacitor C11, R15 connected to the second pin of the control chip, capacitor C10 and resistor R4 connected to the third pin of the control chip, diode D10 connected to resistor R4, capacitor C9 and resistor R3 connected to diode D10, The resistor R14 connected between the fourth pin and the eighth pin of the control chip, the capacitor C19 connected to the fourth pin, the resistor R6 connected to the sixth pin of the control chip, and the full-control MOSFET switch connected to the resistor R6 Tube S, the resistor R5 connected to the full-control MOSFET switch tube S, the capacitor C12 connected to the eighth pin of the control chip, the polar capacitor C8 and the diode D9 connected to the regulator tube D11.
在本发明提供的多路输出单端反激式开关电源中，还可以具有这样的特征：其中，输入整流滤波电路包括：熔断器FU、压敏电阻VSR、热敏电阻NTCR、电容C1、电感、电容C2、电容C3、电容C4、二极管D1、二极管D2、二极管D3、二极管D4和极性电容C5，熔断器FU的一端连接于AC1端口，另一端连接于压敏电阻VSR的一端，该压敏电阻VSR的另一端与AC2端口连接；热敏电阻NTCR一端与熔断器FU连接，另一端连接于电容C1的一端；电容C1的另一端连接于AC2端口上；电容C1连接并联于电感的一端，电感的另一端并联有电容C2，该电容C2的一端与电容C3的一端连接，电容C2的另一端与电容C4的一端连接，电容C3的另一端与电容C4的另一端均接地；二极管D1的正极与电感连接，还与二极管D2的负极连接，二极管D1的负极连接于+V0端口，二极管D2的正极接地；二极管D3的正极与二极管D4的负极均与与电感连接，二极管D3的负极与二极管D4的正极与极性电容C5并联后，再分别与连接于+V0端口和接地。In the multi-output single-ended flyback switching power supply provided by the present invention, it can also have such a feature: wherein, the input rectification filter circuit includes: fuse FU, varistor VSR, thermistor NTCR, capacitor C1, inductor , Capacitor C2, Capacitor C3, Capacitor C4, Diode D1, Diode D2, Diode D3, Diode D4 and Polarity Capacitor C5, one end of the fuse FU is connected to the AC1 port, and the other end is connected to one end of the varistor VSR. The other end of the sensitive resistor VSR is connected to the AC2 port; one end of the thermistor NTCR is connected to the fuse FU, and the other end is connected to one end of the capacitor C1; the other end of the capacitor C1 is connected to the AC2 port; the capacitor C1 is connected in parallel to one end of the inductor , the other end of the inductance is connected in parallel with a capacitor C2, one end of the capacitor C2 is connected to one end of the capacitor C3, the other end of the capacitor C2 is connected to one end of the capacitor C4, the other end of the capacitor C3 and the other end of the capacitor C4 are grounded; the diode D1 The anode of the diode is connected to the inductor, and also connected to the cathode of the diode D2, the cathode of the diode D1 is connected to the +V0 port, the anode of the diode D2 is grounded; the anode of the diode D3 and the cathode of the diode D4 are both connected to the inductor, and the cathode of the diode D3 is connected to the inductor. After the anode of the diode D4 is connected in parallel with the polarity capacitor C5, it is connected to the +V0 port and the ground respectively.
在本发明提供的多路输出单端反激式开关电源中，还可以具有这样的特征：其中，输出整流滤波电路包括：二极管D5、二极管D6、二极管D7、电容C13、电容C14、电容C15、电容C16、电容C17、电容C18、电感L2、电感L3和电感L4，二极管D5的负极与电感L2连接，电感L2的两端分别连接有电容C13和电容C14；二极管D6的负极与电感L3连接，电感L3的两端分别连接有电容C15和电容C16；二极管D7的负极与电感L4连接，电感L4的两端分别连接有电容C17和电容C18。In the multi-channel output single-ended flyback switching power supply provided by the present invention, it can also have such a feature: wherein, the output rectification filter circuit includes: diode D5, diode D6, diode D7, capacitor C13, capacitor C14, capacitor C15, Capacitor C16, capacitor C17, capacitor C18, inductor L2, inductor L3 and inductor L4, the cathode of diode D5 is connected to inductor L2, and the two ends of inductor L2 are respectively connected to capacitor C13 and capacitor C14; the cathode of diode D6 is connected to inductor L3, The two ends of the inductor L3 are respectively connected to the capacitor C15 and the capacitor C16; the cathode of the diode D7 is connected to the inductor L4, and the two ends of the inductor L4 are respectively connected to the capacitor C17 and the capacitor C18.
在本发明提供的多路输出单端反激式开关电源中，还可以具有这样的特征：其中，反馈电路包括：电阻R16、线性光耦合器PC817、电阻R8、电阻R9、可调精密并联稳压器TL431、电阻R11、电阻R10、电阻R12和电阻R13，电阻R16一端与电阻R15的一端连接，电阻R16的另一端接地；线性光耦合器PC817三极管侧的一端与UC3844控制芯片的第八管脚连接，另一端与电阻R16和电阻R15均连接，线性光耦合器PC817二极管侧的正极一端与电阻R8的一端连接，负极一端与电阻R9的一端连接，电阻R8的另一端以及电阻R9的另一端均与电阻R11的一端连接，该电阻R11的另一端与电阻R10的一端连接，该电阻R10的另一端接地；可调精密并联稳压器TL431与电阻R11、电阻R12以及电阻R13均连接，且可调精密并联稳压器TL431接地。In the multi-output single-ended flyback switching power supply provided by the present invention, it can also have the following features: wherein, the feedback circuit includes: resistor R16, linear optocoupler PC817, resistor R8, resistor R9, adjustable precision parallel stabilizer Voltage regulator TL431, resistor R11, resistor R10, resistor R12 and resistor R13, one end of resistor R16 is connected to one end of resistor R15, and the other end of resistor R16 is grounded; one end of linear optocoupler PC817 triode side is connected to the eighth tube of UC3844 control chip The other end is connected to both resistor R16 and resistor R15, the positive end of the diode side of the linear optocoupler PC817 is connected to one end of resistor R8, the negative end is connected to one end of resistor R9, the other end of resistor R8 and the other end of resistor R9 One end is connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the resistor R10, and the other end of the resistor R10 is grounded; the adjustable precision shunt regulator TL431 is connected to the resistor R11, the resistor R12 and the resistor R13, And the adjustable precision shunt regulator TL431 is grounded.
在本发明提供的多路输出单端反激式开关电源中，还可以具有这样的特征：其中，反馈电路输出具有三路输出，分别输出+3.3V/0.5A，+5V/0.5A和+12V/1A三路隔离电压。In the multi-output single-ended flyback switching power supply provided by the present invention, it can also have such a feature: wherein, the output of the feedback circuit has three outputs, respectively outputting +3.3V/0.5A, +5V/0.5A and + 12V/1A three-way isolation voltage.
在本发明提供的多路输出单端反激式开关电源中，还可以具有这样的特征：其中，全控MOSFET开关管S还与二极管D8的负极连接。In the multi-output single-ended flyback switching power supply provided by the present invention, it may also have such a feature: wherein, the full-control MOSFET switching tube S is also connected to the cathode of the diode D8.
发明的作用与效果Function and Effect of Invention
本发明所涉及的多路输出单端反激式开关电源的UC3844控制电路中的全控MOSFET开关管S工作在开关状态，它导通时阻抗小，接近于短路，管压降接近于零；关断时阻抗很大，接近于断路，电流几乎为零。全控MOSFET开关管S不管是导通还是关断，它的功耗很小，所以开关电源的效率可以大幅度地提高。此外，UC3844控制电路中设有稳压器D11能够防止电压损坏UC3844控制芯片。本实施例的一种多路输出单端反激式开关电源的DC-DC电路采用高频变压器，并且全控MOSFET开关管S上的耗散功率大幅度降低，省去了较大的散热片。所以开关电源的体积小，重量轻。本实施例的一种多路输出单端反激式开关电源的反馈电路中设有的线性光耦合器PC817能够使全控MOSFET开关管S得第六管脚输出的驱动信号的占空比减小，从而输出电压下降达到稳压的目的。因此，本实施例的一种多路输出单端反激式开关电源具有重量轻、体积小、发热量低、效率高、性能稳定、使用方便等优点。The full-control MOSFET switching tube S in the UC3844 control circuit of the multi-channel output single-ended flyback switching power supply involved in the present invention works in the switching state, and when it is turned on, the impedance is small, close to a short circuit, and the tube voltage drop is close to zero; When it is turned off, the impedance is very large, close to the open circuit, and the current is almost zero. Whether the full-control MOSFET switch S is turned on or off, its power consumption is very small, so the efficiency of the switching power supply can be greatly improved. In addition, the UC3844 control circuit is equipped with a voltage regulator D11 to prevent the voltage from damaging the UC3844 control chip. The DC-DC circuit of a multi-output single-ended flyback switching power supply in this embodiment adopts a high-frequency transformer, and the power dissipation on the full-control MOSFET switch tube S is greatly reduced, eliminating the need for a larger heat sink . Therefore, the switching power supply is small in size and light in weight. The linear optocoupler PC817 provided in the feedback circuit of a multi-channel output single-ended flyback switching power supply of this embodiment can reduce the duty ratio of the drive signal output by the sixth pin of the full-control MOSFET switch S. Small, so that the output voltage drops to achieve the purpose of voltage regulation. Therefore, the multi-output single-ended flyback switching power supply of this embodiment has the advantages of light weight, small size, low calorific value, high efficiency, stable performance, and convenient use.
附图说明Description of drawings
图1是本发明的实施例中的多路输出单端反激式开关电源的电路结构示意图。FIG. 1 is a schematic diagram of a circuit structure of a multi-output single-ended flyback switching power supply in an embodiment of the present invention.
具体实施方式Detailed ways
为了使本发明实现的技术手段与功效易于明白了解，以下结合实施例及附图对本发明作具体阐述。In order to make the technical means and effects realized by the present invention easy to understand, the present invention will be described in detail below in conjunction with the embodiments and accompanying drawings.
实施例：Example:
图1是本发明的实施例中的多路输出单端反激式开关电源结构示意图，其中，图1(a)是本发明的实施例中的输入整流滤波电路的电路结构示意图；图1(b)是本发明的实施例中的DC-DC变换电路、UC3844控制电路与反馈电路的电路结构示意图，且图1(a)中+V0端口与图1(b)中的+V0端口为同一个端口。Fig. 1 is a schematic structural diagram of a multi-channel output single-ended flyback switching power supply in an embodiment of the present invention, wherein Fig. 1 (a) is a schematic circuit structural diagram of an input rectification filter circuit in an embodiment of the present invention; Fig. 1 ( b) is a schematic diagram of the circuit structure of the DC-DC conversion circuit, UC3844 control circuit and feedback circuit in the embodiment of the present invention, and the +V0 port in Figure 1(a) is the same as the +V0 port in Figure 1(b) a port.
如图1所示，本实施例的一种多路输出单端反激式开关电源，用于将输入的交流电转变为预定电压的输出直流电并进行输出，包括：输入整流滤波电路1、DC-DC变换电路2、UC3844控制电路3和反馈电路4。As shown in Figure 1, a multi-output single-ended flyback switching power supply in this embodiment is used to convert the input AC power into an output DC power of a predetermined voltage and output it, including: input rectification filter circuit 1, DC- DC conversion circuit 2, UC3844 control circuit 3 and feedback circuit 4.
输入整流滤波电路1，用于将输入的交流电变换成直流电通过+V0端口输出。The input rectification and filtering circuit 1 is used to convert the input AC power into DC power and output it through the +V0 port.
输入整流滤波电路1包括：熔断器FU、压敏电阻VSR、热敏电阻NTCR、电容C1、电感、电容C2、电容C3、电容C4、二极管D1、二极管D2、二极管D3、二极管D4和极性电容C5。Input rectification filter circuit 1 includes: fuse FU, varistor VSR, thermistor NTCR, capacitor C1, inductor, capacitor C2, capacitor C3, capacitor C4, diode D1, diode D2, diode D3, diode D4 and polar capacitor C5.
熔断器FU的一端连接于AC1端口，另一端连接于压敏电阻VSR的一端，该压敏电阻VSR的另一端与AC2端口连接。One end of the fuse FU is connected to the AC1 port, and the other end is connected to one end of the varistor VSR, and the other end of the varistor VSR is connected to the AC2 port.
热敏电阻NTCR一端与熔断器FU连接，另一端连接于所述电容C1的一端上。One end of the thermistor NTCR is connected to the fuse FU, and the other end is connected to one end of the capacitor C1.
电容C1的另一端连接于AC2端口上。The other end of the capacitor C1 is connected to the AC2 port.
电容C1连接并联于电感的一端，电感的另一端并联有电容C2，该电容C2的一端与电容C3的一端连接，电容C2的另一端与电容C4的一端连接，电容C3的另一端与电容C4的另一端均接地。Capacitor C1 is connected in parallel with one end of the inductance, and the other end of the inductance is connected in parallel with a capacitor C2. One end of the capacitor C2 is connected to one end of the capacitor C3, the other end of the capacitor C2 is connected to one end of the capacitor C4, and the other end of the capacitor C3 is connected to the capacitor C4. The other end of both are grounded.
二极管D1的正极与电感连接，还与二极管D2的负极连接，二极管D1的负极连接于+V0端口，二极管D2的正极接地。The anode of the diode D1 is connected to the inductor and also connected to the cathode of the diode D2, the cathode of the diode D1 is connected to the +V0 port, and the anode of the diode D2 is grounded.
二极管D3的正极与二极管D4的负极均与与电感连接，二极管D3的负极与二极管D4的正极与极性电容C5并联后，再分别与连接于+V0端口和接地。The anode of the diode D3 and the cathode of the diode D4 are both connected to the inductor, and the cathode of the diode D3 and the anode of the diode D4 are connected in parallel with the polarity capacitor C5, and then respectively connected to the +V0 port and the ground.
DC-DC变换电路2，用于降低直流电的电压从而形成低的直流电压，包括逆变电路和用于将输出电压的纹波变得更为平滑的输出整流滤波电路21。The DC-DC conversion circuit 2 is used to reduce the voltage of the direct current to form a low direct current voltage, and includes an inverter circuit and an output rectification and filtering circuit 21 for smoothing the ripple of the output voltage.
输出整流滤波电路21包括：二极管D5、二极管D6、二极管D7、电容C13、电容C14、电容C15、电容C16、电容C17、电容C18、电感L2、电感L3和电感L4。The output rectifying and filtering circuit 21 includes: a diode D5, a diode D6, a diode D7, a capacitor C13, a capacitor C14, a capacitor C15, a capacitor C16, a capacitor C17, a capacitor C18, an inductor L2, an inductor L3 and an inductor L4.
二极管D5的负极与电感L2连接，电感L2的两端分别连接有电容C13和电容C14。The cathode of the diode D5 is connected to the inductor L2, and the two ends of the inductor L2 are respectively connected to a capacitor C13 and a capacitor C14.
二极管D6的负极与电感L3连接，电感L3的两端分别连接有电容C15和电容C16。The cathode of the diode D6 is connected to the inductance L3, and the two ends of the inductance L3 are respectively connected to the capacitor C15 and the capacitor C16.
二极管D7的负极与电感L4连接，电感L4的两端分别连接有电容C17和电容C18。The cathode of the diode D7 is connected to the inductor L4, and the two ends of the inductor L4 are respectively connected to a capacitor C17 and a capacitor C18.
用于将直流电压逆变为高频变压器作用的交流电压的逆变电路包括连接于+V0端口的电容C6、与电容C6连接的电阻R1、与电阻R1连接的电容C7、与电容C7连接的电阻R2及与电阻R2连接的二极管D8和高频变压器。The inverter circuit used to invert the DC voltage into the AC voltage of the high-frequency transformer includes a capacitor C6 connected to the +V0 port, a resistor R1 connected to the capacitor C6, a capacitor C7 connected to the resistor R1, and a capacitor connected to the capacitor C7. Resistor R2 and diode D8 connected with resistor R2 and high frequency transformer.
UC3844控制电路3，用于将整流输出的电压和高频变压器的电感电流进行采样从而产生不同脉宽的PWM信号。UC3844 control circuit 3 is used to sample the rectified output voltage and the inductive current of the high-frequency transformer to generate PWM signals with different pulse widths.
UC3844控制电路3包括UC3844控制芯片和稳压管D11，与控制芯片第一管脚连接的电阻R7和电容C11、与控制芯片第二管脚连接的R15、与控制芯片第三管脚连接的电容C10和电阻R4、与电阻R4连接的二极管D10、与二极管D10连接的电容C9和电阻R3，连接于控制芯片第四管脚与第八管脚之间的电阻R14，与第四管脚连接的电容C19，与控制芯片第六管脚连接的电阻R6、与电阻R6连接的全控MOSFET开关管S、与全控MOSFET开关管S连接的电阻R5、与控制芯片第八管脚连接的电容C12以及与稳压管D11连接的极性电容C8和二极管D9。UC3844 control circuit 3 includes UC3844 control chip and regulator tube D11, resistor R7 and capacitor C11 connected to the first pin of the control chip, R15 connected to the second pin of the control chip, and capacitor connected to the third pin of the control chip C10 and resistor R4, diode D10 connected to resistor R4, capacitor C9 connected to diode D10 and resistor R3, connected to resistor R14 between the fourth pin and eighth pin of the control chip, connected to the fourth pin Capacitor C19, resistor R6 connected to the sixth pin of the control chip, full-control MOSFET switch S connected to resistor R6, resistor R5 connected to full-control MOSFET switch S, capacitor C12 connected to the eighth pin of the control chip And the polarity capacitor C8 and the diode D9 connected with the regulator tube D11.
全控MOSFET开关管S还与二极管D8的负极连接。The fully-controlled MOSFET switch tube S is also connected to the cathode of the diode D8.
全控MOSFET开关管S由PWM信号驱动工作。The fully-controlled MOSFET switch tube S is driven by a PWM signal.
反馈电路4，用于从输出的电压采样得到误差电压，经过误差放大后输入到UC3844控制电路来控制占空比，从而稳定输出电压。The feedback circuit 4 is used to obtain the error voltage from the output voltage sampling, which is input to the UC3844 control circuit after error amplification to control the duty ratio, thereby stabilizing the output voltage.
反馈电路4包括：电阻R16、线性光耦合器PC817、电阻R8、电阻R9、可调精密并联稳压器TL431、电阻R11、电阻R10、电阻R12和电阻R13。The feedback circuit 4 includes: a resistor R16, a linear optocoupler PC817, a resistor R8, a resistor R9, an adjustable precision shunt regulator TL431, a resistor R11, a resistor R10, a resistor R12 and a resistor R13.
电阻R16一端与电阻R15的一端连接，电阻R16的另一端接地。One end of the resistor R16 is connected to one end of the resistor R15, and the other end of the resistor R16 is grounded.
线性光耦合器PC817三极管侧的一端与UC3844控制芯片的第八管脚连接，另一端与电阻R16和电阻R15均连接，线性光耦合器PC817二极管侧的正极一端与电阻R8的一端连接，负极一端与电阻R9的一端连接，电阻R8的另一端以及电阻R9的另一端均与电阻R11的一端连接，该电阻R11的另一端与电阻R10的一端连接，该电阻R10的另一端接地。One end of the triode side of the linear optocoupler PC817 is connected to the eighth pin of the UC3844 control chip, the other end is connected to both resistor R16 and resistor R15, the positive end of the linear optocoupler PC817 diode side is connected to one end of the resistor R8, and the negative end is connected to One end of the resistor R9 is connected, the other end of the resistor R8 and the other end of the resistor R9 are connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the resistor R10, and the other end of the resistor R10 is grounded.
可调精密并联稳压器TL431与电阻R11、电阻R12以及电阻R13均连接，且可调精密并联稳压器TL431接地。The adjustable precision shunt regulator TL431 is connected to the resistors R11, R12 and R13, and the adjustable precision shunt regulator TL431 is grounded.
反馈电路4输出具有三路输出，分别输出+3.3V/0.5A，+5V/0.5A和+12V/1A三路隔离电压。The output of the feedback circuit 4 has three outputs, respectively outputting three isolated voltages of +3.3V/0.5A, +5V/0.5A and +12V/1A.
本实施例的多路输出单端反激式开关电源的工作过程如下：The working process of the multi-output single-ended flyback switching power supply of this embodiment is as follows:
本实施例的多路输出单端反激式开关电源包括开关电源的启动、开关电源的储能、开关电源的释能和开关电源的稳压。The multi-output single-ended flyback switching power supply of this embodiment includes starting the switching power supply, storing energy of the switching power supply, releasing energy of the switching power supply and stabilizing the voltage of the switching power supply.
开关电源的启动：220V交流电通过输入整流滤波电路得到的300V直流电压分为两路：一路经过高频变压器的初级绕组Np加在全控MOSFET开关管的漏极；另外的一路经过启动电阻R1向C8充电，为全控MOSFET开关管提供启动电压，加在UC3844控制芯片的第七管脚，当C8充电值达到16V时，UC3844控制芯片启动工作，这个过程称为电压的软启动。为了防止冲击电压损坏UC3844控制芯片，在它的第七管脚和地间加一个18V稳压管D11，第八管脚产生的基准电压5V经过R14对C19进行充电，并在第四管脚上形成锯齿波电压信号，它的频率就是电源的工作频率，锯齿波电压信号进入UC3844控制芯片的内部振荡器，产生出频率固定的振荡信号，经过脉冲宽度调制和推挽式输出级的放大后，在第六管脚输出栅极驱动信号使全控MOSFET开关管S导通；Start-up of switching power supply: 220V AC is input into rectification and filtering circuit to obtain 300V DC voltage into two routes: one route passes through the primary winding Np of the high-frequency transformer and is added to the drain of the full-control MOSFET switch tube; the other route passes through the start-up resistor R1 to C8 charging provides the start-up voltage for the fully-controlled MOSFET switch tube, which is added to the seventh pin of the UC3844 control chip. When the charge value of C8 reaches 16V, the UC3844 control chip starts to work. This process is called voltage soft start. In order to prevent the impact voltage from damaging the UC3844 control chip, add an 18V regulator tube D11 between its seventh pin and the ground, and the reference voltage 5V generated by the eighth pin charges C19 through R14, and it is charged on the fourth pin A sawtooth wave voltage signal is formed, and its frequency is the operating frequency of the power supply. The sawtooth wave voltage signal enters the internal oscillator of the UC3844 control chip to generate an oscillating signal with a fixed frequency. After pulse width modulation and amplification of the push-pull output stage, Output the gate drive signal at the sixth pin to turn on the full-control MOSFET switch S;
开关电源的储能：全控MOSFET开关管S导通后高频电压脉冲经过高频变压器的初级绕组，全控MOSFET开关管S的源极漏极，电流检测电阻R5和地电流回路，在初级绕组上产生上正下负的感应电动势，由同名端知变压器次级绕组感应的电动势为负，输出整流二极管反偏截止，高频变压器将电能以磁能形式储存在初级绕组线圈中，这就是储能过程；Energy storage of switching power supply: After the fully-controlled MOSFET switch S is turned on, the high-frequency voltage pulse passes through the primary winding of the high-frequency transformer, the source drain of the fully-controlled MOSFET switch S, the current detection resistor R5 and the ground current loop, in the primary The upper positive and lower negative induced electromotive force is generated on the winding, and the electromotive force induced by the secondary winding of the transformer is negative, and the output rectifier diode is reverse-biased, and the high-frequency transformer stores the electric energy in the primary winding coil in the form of magnetic energy. energy process;
开关电源的释能：当全控MOSFET开关管S锁存器翻转时，第六管脚的输出脉冲停止，全控MOSFET开关管S由导通变成截止。变压器初级绕组产生下正上负的感应电动势，次级绕组产生正向的感应电压，输出整流二极管便导通，初级绕组将储存的能量传递到次级绕组中，再经过整流滤波电路就得到需要的输出电压；Energy release of the switching power supply: When the latch of the full-control MOSFET switch S is turned over, the output pulse of the sixth pin stops, and the full-control MOSFET switch S turns from on to off. The primary winding of the transformer generates positive and negative induced electromotive force, the secondary winding generates a positive induced voltage, the output rectifier diode is turned on, the primary winding transfers the stored energy to the secondary winding, and then the rectification and filtering circuit obtains the required output voltage;
开关电源的稳压：三路+3.3V、+5V、+12V输出电压经过R11、R12、R13分压后和可调精密并联稳压器TL431的基准电压2.5V比较，产生误差电压，并且经过线性光耦合器PC817把误差电压传给UC3844控制芯片，它控制全控MOSFET开关管S的占空比来进行稳压。输出电压升高时，经过分压电阻所得的采样电压也升高，流过线性光耦合器PC817发光二极管的电流增大，光电三极管的导通程度加深，它的集射极电压减小，全控MOSFET开关管S的第六管脚输出的驱动信号的占空比减小，因此输出电压下降，达到了稳压的目的。输出电压下降时，控制过程与上述相反。Voltage regulation of switching power supply: After the three-way +3.3V, +5V, +12V output voltage is divided by R11, R12, R13, it is compared with the reference voltage 2.5V of the adjustable precision shunt regulator TL431 to generate an error voltage, and after The linear optocoupler PC817 transmits the error voltage to the UC3844 control chip, which controls the duty cycle of the full-control MOSFET switch S to stabilize the voltage. When the output voltage rises, the sampling voltage obtained through the voltage dividing resistor also rises, the current flowing through the linear optocoupler PC817 light-emitting diode increases, the conduction degree of the phototransistor deepens, and its collector-emitter voltage decreases. The duty ratio of the drive signal output by controlling the sixth pin of the MOSFET switch S is reduced, so the output voltage drops, and the purpose of voltage stabilization is achieved. When the output voltage drops, the control process is opposite to the above.
实施例的作用与效果Function and effect of embodiment
本实施例的一种多路输出单端反激式开关电源的UC3844控制电路中的全控MOSFET开关管S工作在开关状态，它导通时阻抗小，接近于短路，管压降接近于零；关断时阻抗很大，接近于断路，电流几乎为零。全控MOSFET开关管S不管是导通还是关断，它的功耗很小，所以开关电源的效率可以大幅度地提高。此外，UC3844控制电路中设有稳压器D11能够防止电压损坏UC3844控制芯片。本实施例的一种多路输出单端反激式开关电源的DC-DC电路采用高频变压器，并且全控MOSFET开关管S上的耗散功率大幅度降低，省去了较大的散热片。所以开关电源的体积小，重量轻。本实施例的一种多路输出单端反激式开关电源的反馈电路中设有的线性光耦合器PC817能够使全控MOSFET开关管S得第六管脚输出的驱动信号的占空比减小，从而输出电压下降达到稳压的目的。因此，本实施例的一种多路输出单端反激式开关电源具有重量轻、体积小、发热量低、效率高、性能稳定、使用方便等优点。The full-control MOSFET switching tube S in the UC3844 control circuit of a multi-output single-ended flyback switching power supply of this embodiment works in the switching state, and when it is turned on, the impedance is small, close to a short circuit, and the tube voltage drop is close to zero. ; The impedance is very large when it is turned off, close to the open circuit, and the current is almost zero. Whether the full-control MOSFET switch S is turned on or off, its power consumption is very small, so the efficiency of the switching power supply can be greatly improved. In addition, the UC3844 control circuit is equipped with a voltage regulator D11 to prevent the voltage from damaging the UC3844 control chip. The DC-DC circuit of a multi-output single-ended flyback switching power supply in this embodiment adopts a high-frequency transformer, and the power dissipation on the full-control MOSFET switch tube S is greatly reduced, eliminating the need for a larger heat sink . Therefore, the switching power supply is small in size and light in weight. The linear optocoupler PC817 provided in the feedback circuit of a multi-channel output single-ended flyback switching power supply of this embodiment can reduce the duty ratio of the drive signal output by the sixth pin of the full-control MOSFET switch S. Small, so that the output voltage drops to achieve the purpose of voltage regulation. Therefore, the multi-output single-ended flyback switching power supply of this embodiment has the advantages of light weight, small size, low calorific value, high efficiency, stable performance, and convenient use.
上述实施方式为本发明的优选案例，并不用来限制本发明的保护范围。The above embodiments are preferred examples of the present invention, and are not intended to limit the protection scope of the present invention.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810294233.5ACN108365765A (en) | 2018-03-30 | 2018-03-30 | A kind of multiple-channel output single-end flyback switching power supply |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810294233.5ACN108365765A (en) | 2018-03-30 | 2018-03-30 | A kind of multiple-channel output single-end flyback switching power supply |
| Publication Number | Publication Date |
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| CN108365765Atrue CN108365765A (en) | 2018-08-03 |
| Application Number | Title | Priority Date | Filing Date |
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| CN201810294233.5APendingCN108365765A (en) | 2018-03-30 | 2018-03-30 | A kind of multiple-channel output single-end flyback switching power supply |
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| CB03 | Change of inventor or designer information | Inventor after:Chen Hua Inventor after:Li Feng Inventor after:Song Jie Inventor after:Liu Zheng Inventor after:Dai Xinglian Inventor before:Chen Hua | |
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