技术领域technical field
本发明属于开关电源技术领域，具体涉及一种反激式开关电源及其控制电路。The invention belongs to the technical field of switching power supplies, and in particular relates to a flyback switching power supply and a control circuit thereof.
背景技术Background technique
开关电源是利用现代电力电子技术，控制开关管开通和关断的时间比率，维持稳定输出电压的一种电源，一般由脉冲宽度调制控制单片机和MOSFET构成。目前，开关电源以小型、轻量和高效率的特点，被广泛应用于工业自动化控制、军工设备、科研设备等领域，是当今电子信息产业飞速发展不可缺少的一种电源方式。Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching tube on and off to maintain a stable output voltage. It is generally composed of pulse width modulation control single-chip microcomputer and MOSFET. At present, switching power supply is widely used in industrial automation control, military equipment, scientific research equipment and other fields due to its small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of today's electronic information industry.
在基本的Buck、Boost以及Cuk等DC/DC变换器中引入隔离变压器，可以使变换器的输入电源与负载之间实现电气隔离，提高变换器运行的安全可靠性和电磁兼容性，主要包括正激式开关电源和反激式开关电源。其中，反激式开关电源相较于正激式开关电源，因其结构简单、价格便宜、输入范围宽等特点备受关注，适用于各种不同的电压等级场合，广泛应用于各种辅助电源和小功率电源中。The introduction of isolation transformers into basic DC/DC converters such as Buck, Boost, and Cuk can achieve electrical isolation between the input power of the converter and the load, and improve the safety, reliability and electromagnetic compatibility of the converter. Excited switching power supply and flyback switching power supply. Among them, compared with the forward switching power supply, the flyback switching power supply has attracted much attention because of its simple structure, low price, and wide input range. It is suitable for various voltage levels and is widely used in various auxiliary power supplies. and low-power power supply.
单管反激变换器主开关，其开通与关断电压应力较大，难以用于电压较高的场合。而双管反激变换器的主开关电压应力仅为输入电压，且漏感能量可回馈到输入侧，无需增加任何吸收电路，因而整机效率也比较高，应用双管串联技术，使其非常适用于较高输入电压和高性能要求的场合。The main switch of the single-tube flyback converter has a large turn-on and turn-off voltage stress, so it is difficult to be used in high-voltage occasions. However, the voltage stress of the main switch of the dual-transistor flyback converter is only the input voltage, and the leakage inductance energy can be fed back to the input side without adding any absorption circuit, so the efficiency of the whole machine is relatively high. The application of dual-transistor series technology makes it very Suitable for occasions with higher input voltage and high performance requirements.
反激式开关电源为了实现输出的稳定，一般通过环路实现稳定。其中，最经典、应用极广的方式是副边光耦反馈环路控制法。In order to achieve stable output, the flyback switching power supply generally achieves stability through a loop. Among them, the most classic and widely used method is the secondary optocoupler feedback loop control method.
该控制方法一般采用TL431这种三端基准集成电路，结构如图1所示。其中，U5即为TL431，R5、R6、C2、C3、R9、R10构成调节控制模块。U5的采样端通过电阻R9连接有输出电压信号，以对其进行控制。This control method generally uses a three-terminal reference integrated circuit such as TL431, and its structure is shown in Figure 1. Among them, U5 is TL431, and R5, R6, C2, C3, R9, and R10 form a regulation control module. The sampling terminal of U5 is connected with an output voltage signal through a resistor R9 to control it.
该电路对输出电压信号进行采样，当输出电压升高时，TL431的吸收电流变大，流过隔离光耦U2的电流变大，隔离光耦U2的输出端的电流也正比例变大，脉宽调制控制器U3输出使原边的开关电源的占空比变小，这样经过反激变压器T1输出的能量变小，使得反激式开关电源的输出电压下降到输出电压预设值；当输出电压下降时，TL431的输出电流变小，流过光耦U2的电流变小，光耦U2的输出端的电流也变小，脉宽调制控制器U3输出使原边的开关电源的占空比变大，这样经过反激变压器T1输出的能量变大，使得反激式开关电源的输出电压上升到输出电压预设值。This circuit samples the output voltage signal. When the output voltage rises, the absorption current of TL431 becomes larger, the current flowing through the isolated optocoupler U2 becomes larger, and the current at the output terminal of the isolated optocoupler U2 also becomes proportionally larger, and the pulse width modulation The output of the controller U3 makes the duty cycle of the switching power supply on the primary side smaller, so that the energy output through the flyback transformer T1 becomes smaller, so that the output voltage of the flyback switching power supply drops to the output voltage preset value; when the output voltage drops , the output current of TL431 becomes smaller, the current flowing through the optocoupler U2 becomes smaller, the current of the output terminal of optocoupler U2 also becomes smaller, and the output of the pulse width modulation controller U3 increases the duty cycle of the switching power supply on the primary side. In this way, the energy output through the flyback transformer T1 becomes larger, so that the output voltage of the flyback switching power supply rises to a preset value of the output voltage.
该控制方法只对输出电压进行控制，电源整体性能的稳定性、可靠性较低。This control method only controls the output voltage, and the stability and reliability of the overall performance of the power supply are low.
发明内容Contents of the invention
本发明的目的在于提供一种反激式开关电源及其控制电路，用以解决只对输出电压进行控制时电源整体性能的稳定性、可靠性较低的问题。The object of the present invention is to provide a flyback switching power supply and its control circuit to solve the problem of low stability and reliability of the overall performance of the power supply when only the output voltage is controlled.
为解决上述技术问题，本发明的技术方案为：In order to solve the problems of the technologies described above, the technical solution of the present invention is:
本发明的一种反激式开关电源控制电路，包括用于输出PWM以驱动开关管导通与关断的脉冲调制控制器，所述脉冲调制控制器的比较端口连接调节控制模块的输出端，所述调节控制模块包括可控精密稳压源，所述可控精密稳压源的采样端用于连接输出电压信号，还包括过载保护模块，所述过载保护模块包括第一比较器，所述第一比较器的同相输入端用于连接输出电流信号，反相输入端连接第一基准值，输出端连接所述可控精密稳压源的采样端。A flyback switching power supply control circuit of the present invention includes a pulse modulation controller for outputting PWM to drive the switching tube to be turned on and off, the comparison port of the pulse modulation controller is connected to the output terminal of the regulation control module, The adjustment control module includes a controllable precision voltage regulator, the sampling terminal of the controllable precision voltage regulator is used to connect the output voltage signal, and also includes an overload protection module, the overload protection module includes a first comparator, the The non-inverting input terminal of the first comparator is used to connect the output current signal, the inverting input terminal is connected to the first reference value, and the output terminal is connected to the sampling terminal of the controllable precision voltage stabilization source.
进一步地，所述可控精密稳压源的采样端通过第一电容连接输出电压信号，输出端连接第一隔离光耦的原边，第一隔离光耦的副边连接所述脉冲调制控制器的比较端口。Further, the sampling terminal of the controllable precision voltage regulator is connected to the output voltage signal through the first capacitor, the output terminal is connected to the primary side of the first isolated optocoupler, and the secondary side of the first isolated optocoupler is connected to the pulse modulation controller comparison port.
进一步地，控制电路还包括输出电压过压保护模块，所述输出电压过压保护模块包括第二比较器，所述第二比较器的同相输入端用于连接输出电压信号，反相输入端连接第二基准值，输出端连接第二隔离光耦的原边，第二隔离光耦的副边连接所述脉冲调制控制器的比较端口。Further, the control circuit also includes an output voltage overvoltage protection module, the output voltage overvoltage protection module includes a second comparator, the non-inverting input terminal of the second comparator is used to connect the output voltage signal, and the inverting input terminal is connected to For the second reference value, the output terminal is connected to the primary side of the second isolated optocoupler, and the secondary side of the second isolated optocoupler is connected to the comparison port of the pulse modulation controller.
进一步地，控制电路还包括输入电压保护模块，所述输入电压保护模块包括连接输入母线电压信号的电阻分压电路，所述电阻分压电路的分压端连接所述脉冲调制控制器的分压端口。Further, the control circuit also includes an input voltage protection module, the input voltage protection module includes a resistor voltage divider circuit connected to the input bus voltage signal, and the voltage divider end of the resistor voltage divider circuit is connected to the voltage divider of the pulse modulation controller. port.
进一步地，控制电路还包括连接所述脉冲调制控制器的供电端口的启动电压限制模块，所述启动电压限值模块包括一个三极管，射极接地，集电极通过上拉电阻连接输入母线电压信号，集电极还连接供电端口；所述输入母线电压信号经过电阻与稳压管的分压，连接到所述三极管的基极。Further, the control circuit also includes a starting voltage limiting module connected to the power supply port of the pulse modulation controller, the starting voltage limiting module includes a triode, the emitter is grounded, and the collector is connected to the input bus voltage signal through a pull-up resistor. The collector is also connected to the power supply port; the input bus voltage signal is connected to the base of the triode through the voltage division of the resistor and the voltage regulator tube.
本发明的一种反激式开关电源，包括变压器，还包括用于输出PWM以驱动开关管导通与关断的脉冲调制控制器，所述脉冲调制控制器的比较端口连接调节控制模块的输出端，所述调节控制模块包括可控精密稳压源，所述可控精密稳压源的采样端用于连接输出电压信号，还包括过载保护模块，所述过载保护模块包括第一比较器，所述第一比较器的同相输入端用于连接输出电流信号，反相输入端连接第一基准值，输出端连接所述可控精密稳压源的采样端。A flyback switching power supply of the present invention includes a transformer, and also includes a pulse modulation controller for outputting PWM to drive the switching tube to turn on and off, and the comparison port of the pulse modulation controller is connected to the output of the regulation control module terminal, the adjustment control module includes a controllable precision voltage regulator, the sampling terminal of the controllable precision voltage regulator is used to connect the output voltage signal, and also includes an overload protection module, the overload protection module includes a first comparator, The non-inverting input terminal of the first comparator is used to connect the output current signal, the inverting input terminal is connected to the first reference value, and the output terminal is connected to the sampling terminal of the controllable precision voltage regulator.
进一步地，所述可控精密稳压源的采样端通过第一电容连接输出电压信号，输出端连接第一隔离光耦的原边，第一隔离光耦的副边连接所述脉冲调制控制器的比较端口。Further, the sampling terminal of the controllable precision voltage regulator is connected to the output voltage signal through the first capacitor, the output terminal is connected to the primary side of the first isolated optocoupler, and the secondary side of the first isolated optocoupler is connected to the pulse modulation controller comparison port.
进一步地，还包括输出电压过压保护模块，所述输出电压过压保护模块包括第二比较器，所述第二比较器的同相输入端用于连接输出电压信号，反相输入端连接第二基准值，输出端连接第二隔离光耦的原边，第二隔离光耦的副边连接所述脉冲调制控制器的比较端口。Further, it also includes an output voltage overvoltage protection module, the output voltage overvoltage protection module includes a second comparator, the non-inverting input terminal of the second comparator is used to connect the output voltage signal, and the inverting input terminal is connected to the second The reference value, the output terminal is connected to the primary side of the second isolated optocoupler, and the secondary side of the second isolated optocoupler is connected to the comparison port of the pulse modulation controller.
进一步地，还包括输入电压保护模块，所述输入电压保护模块包括连接输入母线电压信号的电阻分压电路，所述电阻分压电路的分压端连接所述脉冲调制控制器的分压端口。Further, it also includes an input voltage protection module, the input voltage protection module includes a resistor voltage divider circuit connected to the input bus voltage signal, and the voltage divider end of the resistor voltage divider circuit is connected to the voltage divider port of the pulse modulation controller.
进一步地，还包括连接所述脉冲调制控制器的供电端口的启动电压限制模块，所述启动电压限值模块包括一个三极管，射极接地，集电极通过上拉电阻连接输入母线电压信号，集电极还连接供电端口；所述输入母线电压信号经过电阻与稳压管的分压，连接到所述三极管的基极。Further, it also includes a starting voltage limiting module connected to the power supply port of the pulse modulation controller, the starting voltage limiting module includes a triode, the emitter is grounded, the collector is connected to the input bus voltage signal through a pull-up resistor, and the collector The power supply port is also connected; the input bus voltage signal is connected to the base of the triode through the voltage division of the resistor and the voltage regulator tube.
本发明的有益效果：Beneficial effects of the present invention:
本发明的反激式开关电源控制电路，能够应用于反激式开关电源，在现有对输出电压进行副边光耦反馈环路控制的基础上，增加了过载保护模块，即根据输出电压和电流过载信号来通过调节控制模块对改变调节控制模块输出电流的大小，脉冲调制控制器根据该电流的大小来调节输出信号占空比，最终使输出电压变化，从而达到稳压的目的。本发明根据输出电压和电流过载信号两者的变化来对输出电压进行控制，相对于单一通过输出电压来进行控制时，可靠性高，提高了动态响应速度，从而精准控制开关频率，调节占空比。而且，该控制电路结构简单，成本低，体积小，使用范围广，对电路的控制和驱动能力较高。The flyback switching power supply control circuit of the present invention can be applied to the flyback switching power supply. On the basis of the existing secondary optocoupler feedback loop control on the output voltage, an overload protection module is added, that is, according to the output voltage and The current overload signal is used to adjust the control module to change the output current of the control module, and the pulse modulation controller adjusts the duty cycle of the output signal according to the magnitude of the current, and finally changes the output voltage to achieve the purpose of voltage regulation. The present invention controls the output voltage according to the changes of the output voltage and the current overload signal. Compared with the single control by the output voltage, the reliability is high, and the dynamic response speed is improved, so as to accurately control the switching frequency and adjust the duty Compare. Moreover, the control circuit has the advantages of simple structure, low cost, small volume, wide application range, and high control and drive capability of the circuit.
进一步地，反激式开关电源及其控制电路，设计了包括输出电压过压保护、输入电压过压保护在内的多层保护电路，使得该反激式开关电源及其控制电路的安全性、可靠性较高，电磁干扰小，抗干扰能力强，使得电路更加稳定。Further, the flyback switching power supply and its control circuit are designed with a multi-layer protection circuit including output voltage overvoltage protection and input voltage overvoltage protection, so that the safety of the flyback switching power supply and its control circuit, The reliability is high, the electromagnetic interference is small, and the anti-interference ability is strong, which makes the circuit more stable.
附图说明Description of drawings
图1是现有技术的副边光耦反馈环路控制方法电路图；Fig. 1 is the circuit diagram of the prior art secondary optocoupler feedback loop control method;
图2是本发明的开关电源控制电路图。Fig. 2 is a control circuit diagram of the switching power supply of the present invention.
具体实施方式detailed description
为使本发明的目的、技术方案及优点更加清楚，下面结合附图及实施例，对本发明作进一步的详细说明。In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.
本发明的反激式开关电源，包括用于对直流母线的高压进行滤波的输入滤波电路、由两个串联的MOS管、变压器、输出滤波电路以及控制电路组成。变压器驱动控制两个MOS管的导通与关断以进行变压器充电与反激式放电。其中，控制电路如图2所示。The flyback switching power supply of the present invention includes an input filter circuit for filtering the high voltage of the DC bus, and is composed of two series-connected MOS transistors, a transformer, an output filter circuit and a control circuit. The transformer drive controls the turn-on and turn-off of the two MOS tubes for transformer charging and flyback discharge. Among them, the control circuit is shown in Figure 2.
整体来说，该控制电路由可控精密稳压源U5组成调节控制模块对输出电压和电流过载信号进行调节控制，通过隔离光耦U1、U2实现对原边、副边的隔离，U3为脉冲调制控制器，输出PWM波，在经过高频驱动变压器T1进行分路同步，将驱动信号输送到功率MOS管进行驱动。On the whole, the control circuit is composed of a controllable precision voltage regulator U5 to adjust the control module to adjust and control the output voltage and current overload signals. The isolation of the primary side and the secondary side is realized by isolating the optocoupler U1 and U2, and U3 is the pulse The modulation controller outputs PWM waves, and after the high-frequency driving transformer T1 performs branch synchronization, the driving signal is sent to the power MOS tube for driving.
一般可控精密稳压源U5可选用UC3843，其最大的优点是外界元器件极少，外围电路装配简单。Generally, UC3843 can be selected as the controllable precision voltage regulator U5, and its biggest advantage is that there are few external components and the peripheral circuit assembly is simple.
可控精密稳压源U5的外围电路包括电阻R5、电阻R6、电容C3、C2和电阻R10，具体连接方式见图2。电阻R6和电容C3串联后与电容C2串联，将其并联在可控精密稳压源U5的采样端和负端两边；可控精密稳压源U5的正端接地，负端连接隔离光耦U2的发光二极管的阴极(U2的2管脚)，发光二极管的阳极(U2的1管脚)连接输出电压信号，隔离光耦U2的发光二极管的两端并联有电阻R5，输出电压信号通过电阻R9与可控精密稳压源U5的采样端连接，可控精密稳压源U5的采样端还通过电阻R10与地相连；U5的采样端连接有输出电流信号连接运算放大器U4B的同相端(U4B的5管脚)，反向端(U4B的6管脚)连接Vcc，输出端(U4B的7管脚)连接U5的采样端；隔离光耦U2的光电三极管的发射极(隔离光耦U2的3管脚)接地，隔离光耦U2的光电三极管的集电极(隔离光耦U2的4管脚)连接脉冲调制控制器U3的比较端口(U3的7管脚)和脉冲调制控制器U3的电位端口(U3的6管脚)，并通过电容C1接地。The peripheral circuit of the controllable precision voltage regulator U5 includes resistor R5, resistor R6, capacitors C3, C2 and resistor R10, the specific connection method is shown in Figure 2. Resistor R6 and capacitor C3 are connected in series with capacitor C2, and connected in parallel to the sampling terminal and negative terminal of the controllable precision voltage regulator U5; the positive terminal of the controllable precision voltage regulator U5 is grounded, and the negative terminal is connected to the isolation optocoupler U2 The cathode of the LED (Pin 2 of U2), the anode of the LED (Pin 1 of U2) are connected to the output voltage signal, and the two ends of the LED of the isolated optocoupler U2 are connected in parallel with a resistor R5, and the output voltage signal passes through the resistor R9 It is connected with the sampling terminal of the controllable precision voltage regulator U5, and the sampling terminal of the controllable precision voltage regulator U5 is also connected to the ground through the resistor R10; the sampling terminal of U5 is connected with the output current signal and connected to the non-inverting terminal of the operational amplifier U4B (U4B’s 5 pins), the reverse end (6 pins of U4B) is connected to Vcc, the output end (7 pins of U4B) is connected to the sampling end of U5; the emitter of the phototransistor of the isolated optocoupler U2 (3 pins of the isolated optocoupler U2 Pin) is grounded, and the collector of the phototransistor of the isolated optocoupler U2 (pin 4 of the isolated optocoupler U2) is connected to the comparison port (pin 7 of U3) of the pulse modulation controller U3 and the potential port of the pulse modulation controller U3 (Pin 6 of U3), and grounded through capacitor C1.
隔离光耦U2的光电三极管的集电极(U2的4管脚)还通过电阻R7连接脉冲调制控制器U3的时钟端口(U3的5管脚)，脉冲调制控制器U3的时钟端口(U3的5管脚)还通过电容C4接地。脉冲调制控制器U3的检流端口(U3的3管脚)通过电阻R8连接输入电流的采样支路。脉冲调制控制器U3的驱动端口(U3的2管脚)连接高频驱动变压器T1原边的同名端(T1的1接口)，另一端(T1的2接口)接地。The collector (4 pins of U2) of the phototransistor of the isolated optocoupler U2 is also connected to the clock port (5 pins of U3) of the pulse modulation controller U3 through the resistor R7, and the clock port (5 pins of U3) of the pulse modulation controller U3 Pin) is also grounded through capacitor C4. The current detection port (pin 3 of U3) of the pulse modulation controller U3 is connected to the sampling branch of the input current through a resistor R8. The drive port (pin 2 of U3) of the pulse modulation controller U3 is connected to the same-named end (interface 1 of T1) of the primary side of the high-frequency drive transformer T1, and the other end (interface 2 of T1) is grounded.
该控制电路还包括由运算放大器U4A和隔离光耦U1组成的输出电压过压保护模块。输出电压信号连接运算放大器U4A的同相端(U4A的3管脚)，反向端接Vcc(U4A的2管脚)，输出端(U4A的1管脚)连接隔离光耦U2的发光二极管的阳极(U1的1管脚)，阴极(U1的2管脚)接地；隔离光耦U2的光电三极管的集电极(U1的4管脚)连接脉冲调制控制器U3的比较端口(U3的7管脚)，发射极(U1的3管脚)接地。The control circuit also includes an output voltage overvoltage protection module composed of an operational amplifier U4A and an isolated optocoupler U1. The output voltage signal is connected to the non-inverting terminal of the operational amplifier U4A (3 pins of U4A), the reverse terminal is connected to Vcc (2 pins of U4A), and the output terminal (1 pin of U4A) is connected to the anode of the light-emitting diode of the isolated optocoupler U2 (Pin 1 of U1), the cathode (Pin 2 of U1) is grounded; the collector of the phototransistor of the isolated optocoupler U2 (Pin 4 of U1) is connected to the comparison port of the pulse modulation controller U3 (Pin 7 of U3 ), the emitter (3 pins of U1) is grounded.
该控制电路还包括由电阻R1和电阻R3组成的输入电压过压保护模块。输入电压采样支路通过串联的电阻R1、电阻R3接地，电阻R1和电阻R3的连接点连接脉冲调制控制器U3的过压端口(U3的8管脚)。The control circuit also includes an input voltage overvoltage protection module composed of a resistor R1 and a resistor R3. The input voltage sampling branch is grounded through the series connected resistors R1 and R3, and the connection point of the resistors R1 and R3 is connected to the overvoltage port of the pulse modulation controller U3 (pin 8 of U3).
该控制电路还包括启动电压限制模块。输入母线通过电阻R11连接稳压管D1的阴极和三极管Q1的基极，D1阳极接地。输入母线还通过电阻R2连接三极管Q1的集电极，反射极接地，Q1的集电极和反射极之间并联有电容C5，Q1的集电极还连接脉冲调制控制器U3的电源端口(U3的1管脚)。The control circuit also includes a starting voltage limiting module. The input bus is connected to the cathode of the voltage regulator D1 and the base of the triode Q1 through the resistor R11, and the anode of D1 is grounded. The input bus is also connected to the collector of the triode Q1 through the resistor R2, and the reflector is grounded. A capacitor C5 is connected in parallel between the collector and the reflector of Q1. The collector of Q1 is also connected to the power port of the pulse modulation controller U3 (1 tube of U3 foot).
该控制电路的功能及工作原理为：The function and working principle of the control circuit are:
电阻R7、电容C4通过脉冲调制控制器U3控制输出的PWM频率，经过高频驱动变压器T1放大整理增加带载能力，输送给功率管。Resistor R7 and capacitor C4 control the output PWM frequency through the pulse modulation controller U3, and are amplified and sorted by the high-frequency drive transformer T1 to increase the load capacity, and then sent to the power tube.
电阻R8对原边电路进行采样，电流超过设定值会关闭脉冲调制控制器U3。The resistor R8 samples the primary circuit, and the pulse modulation controller U3 will be turned off if the current exceeds the set value.
当母线电压开始建立时，Q1的集电极电压较低，Q1截止，脉冲调制控制器U3的供电电压即为输入母线电压；当输入母线电压较大时，大于D1的稳定电压值时，Q1导通，输入母线电压经过电阻R2分压后，给脉冲调制控制器U3的供电电压。从而使得脉冲调制控制器U3的供电电压不至于太大而对U3有所损坏。When the bus voltage starts to build up, the collector voltage of Q1 is low, Q1 cuts off, and the power supply voltage of the pulse modulation controller U3 is the input bus voltage; when the input bus voltage is larger than the stable voltage value of D1, Q1 conducts Through, the input bus voltage is divided by the resistor R2, and then the power supply voltage for the pulse modulation controller U3. Therefore, the power supply voltage of the pulse modulation controller U3 will not be too large to damage U3.
同时，电阻R1和电阻R3实时监测输入电压是否过压。当发生过压时，电阻R3分压较大，脉冲调制控制器U3的过压端口采样到该信息，脉冲调制控制器U3进行内部逻辑控制计算进行相应处理。At the same time, the resistors R1 and R3 monitor whether the input voltage is overvoltage in real time. When an overvoltage occurs, the voltage divided by the resistor R3 is large, and the overvoltage port of the pulse modulation controller U3 samples the information, and the pulse modulation controller U3 performs internal logic control calculations to perform corresponding processing.
当发生过载时，即输出电流升高，U4B的5管脚超过U4B的6管脚的基准值后，U4B的7管脚输出高电平；当未发生过载，即输出电流在正常范围内时，U4B的7管脚输出低电平。When an overload occurs, that is, the output current rises, and after the 5 pin of U4B exceeds the reference value of the 6 pin of U4B, the 7 pin of U4B outputs a high level; when no overload occurs, that is, the output current is within the normal range , U4B pin 7 outputs low level.
可控精密稳压源U5的采样端会根据输出电压及U4B的输出情况，当采样端电压升高时，可控精密稳压源U5的吸收电流变大，流过隔离光耦U2的电流变大，隔离光耦U2的输出端的电流也正比例变大，即U2的4管脚输出的电流变大；当采样端电压降低时，可控精密稳压源U5的输出电流变小，经过隔离光耦U2的电流变小，隔离光耦U2的输出端的电流也变小，即U2的4管脚输出的电流变小。The sampling terminal of the controllable precision voltage regulator U5 will be based on the output voltage and the output of U4B. When the voltage of the sampling terminal rises, the absorption current of the controllable precision voltage regulator U5 will become larger, and the current flowing through the isolated optocoupler U2 will become larger. large, the current at the output terminal of the isolated optocoupler U2 also increases proportionally, that is, the current output by the 4 pins of U2 increases; The current of the coupler U2 becomes smaller, and the current of the output terminal of the isolated optocoupler U2 also becomes smaller, that is, the current output by the 4-pin of U2 becomes smaller.
当输出电压继续升高达到一定值时，即U4A的3管脚电压其超过U4A的2管脚的基准电压Vcc后，U4A的1管脚输出高电平，使得隔离光耦U1的发光二极管导通，发光二极管发光，光电三极管导通，U1的4管脚输出低电平，U1的4管脚输出电流。当输出电压未超过U4A的2管脚的基准电压Vcc时，U4A的1管脚输出低电平，发光二极管不发光，光电三极管不导通，U1的4管脚没有电流输出。When the output voltage continues to rise to a certain value, that is, after the voltage of pin 3 of U4A exceeds the reference voltage Vcc of pin 2 of U4A, pin 1 of U4A outputs a high level, so that the light-emitting diode of the isolated optocoupler U1 conducts On, the light-emitting diode emits light, the phototransistor is turned on, the 4-pin of U1 outputs low level, and the 4-pin of U1 outputs current. When the output voltage does not exceed the reference voltage Vcc of pin 2 of U4A, pin 1 of U4A outputs a low level, the light-emitting diode does not emit light, the phototransistor does not conduct, and pin 4 of U1 has no current output.
然后，脉冲调制控制器U3的比较端口(U3的7管脚)根据电流的大小，调节U3输出信号占空比，使输出电压变化。当电流变大时，输出控制使原边的开关电源的占空比变小，这样经过高频驱动变压器T1输出的能量变小，使得反激变压器开关电源的输出电压下降到输出电压预设值；当电流变小时，输出控制使原边的开关电源的占空比变大，这样经过高频驱动变压器T1输出的能量变大，使得反激式开关电源的输出电压上升到输出电压预设值。这样一种动态的反馈调节，从而达到稳压的目的，完成对输出电压、负载的动态控制与调节。Then, the comparison port (pin 7 of U3) of the pulse modulation controller U3 adjusts the duty cycle of the output signal of U3 according to the magnitude of the current, so that the output voltage changes. When the current becomes larger, the output control makes the duty ratio of the switching power supply on the primary side smaller, so that the energy output by the high-frequency drive transformer T1 becomes smaller, so that the output voltage of the flyback transformer switching power supply drops to the output voltage preset value ; When the current becomes smaller, the output control increases the duty cycle of the switching power supply on the primary side, so that the energy output by the high-frequency drive transformer T1 becomes larger, so that the output voltage of the flyback switching power supply rises to the output voltage preset value . Such a dynamic feedback adjustment can achieve the purpose of voltage stabilization and complete the dynamic control and adjustment of the output voltage and load.
本发明能够适用于双管反激变换器，它能够在非常宽的输入范围内控制两个开关管的快速开通、关断，从而实现能量的转换与传递，解决单个开关管耐压不足的问题，提高控制的精准能力，整个控制电路响应速度快、能耗小、PCB布板体积小。The present invention can be applied to a dual-tube flyback converter, and it can control the rapid turn-on and turn-off of two switch tubes within a very wide input range, thereby realizing energy conversion and transmission, and solving the problem of insufficient withstand voltage of a single switch tube , improve the precision of control, the entire control circuit has fast response speed, low energy consumption, and small PCB layout.
尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的保护范围应由所附的权利要求来限定。Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710661157.2ACN107579648A (en) | 2017-08-04 | 2017-08-04 | A flyback switching power supply and its control circuit |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710661157.2ACN107579648A (en) | 2017-08-04 | 2017-08-04 | A flyback switching power supply and its control circuit |
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| CN107579648Atrue CN107579648A (en) | 2018-01-12 |
| Application Number | Title | Priority Date | Filing Date |
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| CN201710661157.2APendingCN107579648A (en) | 2017-08-04 | 2017-08-04 | A flyback switching power supply and its control circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108736706A (en)* | 2018-08-01 | 2018-11-02 | 杭州老板电器股份有限公司 | Controllable switch power supply and purification water tank comprising the power supply |
| CN110943734A (en)* | 2019-12-12 | 2020-03-31 | 中环天仪股份有限公司 | Isolation pulse output circuit with overload protection function and implementation method |
| CN114268216A (en)* | 2022-03-01 | 2022-04-01 | 合肥博雷电气有限公司 | Auxiliary power supply starting control system and method for ultra-high voltage input switching power supply |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7859862B2 (en)* | 2007-09-17 | 2010-12-28 | Richtek Technology Corp. | Apparatus and method for regulating constant output voltage and current on primary side in a flyback converter |
| CN204290699U (en)* | 2014-12-10 | 2015-04-22 | 深圳市金威源科技股份有限公司 | A kind of Switching Power Supply protection reference circuit based on TL431 feedback |
| CN204538973U (en)* | 2015-01-23 | 2015-08-05 | 山东艾诺仪器有限公司 | A kind of reverse exciting switching voltage regulator with protective circuit |
| EP1130751B1 (en)* | 2000-03-02 | 2016-06-22 | THOMSON multimedia S.A. | Switched mode power supply with protection circuit against overvoltage |
| CN106059025A (en)* | 2016-02-05 | 2016-10-26 | 广东欧珀移动通信有限公司 | Charging system and power adapter for terminals |
| CN205753993U (en)* | 2016-03-22 | 2016-11-30 | 深圳Tcl数字技术有限公司 | Switching Power Supply and electronic installation |
| CN106685205A (en)* | 2017-03-23 | 2017-05-17 | 广州市爱浦电子科技有限公司 | Power supply starting circuit having low output short-circuit protection power consumption |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1130751B1 (en)* | 2000-03-02 | 2016-06-22 | THOMSON multimedia S.A. | Switched mode power supply with protection circuit against overvoltage |
| US7859862B2 (en)* | 2007-09-17 | 2010-12-28 | Richtek Technology Corp. | Apparatus and method for regulating constant output voltage and current on primary side in a flyback converter |
| CN204290699U (en)* | 2014-12-10 | 2015-04-22 | 深圳市金威源科技股份有限公司 | A kind of Switching Power Supply protection reference circuit based on TL431 feedback |
| CN204538973U (en)* | 2015-01-23 | 2015-08-05 | 山东艾诺仪器有限公司 | A kind of reverse exciting switching voltage regulator with protective circuit |
| CN106059025A (en)* | 2016-02-05 | 2016-10-26 | 广东欧珀移动通信有限公司 | Charging system and power adapter for terminals |
| CN205753993U (en)* | 2016-03-22 | 2016-11-30 | 深圳Tcl数字技术有限公司 | Switching Power Supply and electronic installation |
| CN106685205A (en)* | 2017-03-23 | 2017-05-17 | 广州市爱浦电子科技有限公司 | Power supply starting circuit having low output short-circuit protection power consumption |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108736706A (en)* | 2018-08-01 | 2018-11-02 | 杭州老板电器股份有限公司 | Controllable switch power supply and purification water tank comprising the power supply |
| CN110943734A (en)* | 2019-12-12 | 2020-03-31 | 中环天仪股份有限公司 | Isolation pulse output circuit with overload protection function and implementation method |
| CN114268216A (en)* | 2022-03-01 | 2022-04-01 | 合肥博雷电气有限公司 | Auxiliary power supply starting control system and method for ultra-high voltage input switching power supply |
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