CN204156724U - A kind of rotating forward positive voltage feedback circuit - Google Patents

本实用新型公开了一种正转正电源电压反馈电路，包括输入储能滤波电容、BOOST升压电路和PWM控制器；BOOST升压电路的输出电容、二极管阴极的连接点与第一采样电阻连接，所述第一采样电阻与三极管发射极连接，所述三极管集电极与第二采样电阻一端、PWM控制器的误差放大器输入端连接，所述第二采样电阻另一端接地；所述三极管基极与第三采样电阻一端连接，所述第三采样电阻另一端输入正电压；浮地正电压输出端自所述输出电容、二极管阴极的连接点引出。本实用新型利用三极管电流放大功能，实现了输出电压采样反馈，且输出电压大小不会受到电阻精度的影响，电路结构简单，成本低，输出精度高。

The utility model discloses a forward-to-positive power supply voltage feedback circuit, which comprises an input energy storage filter capacitor, a BOOST boost circuit and a PWM controller; the output capacitor of the BOOST boost circuit and the connection point of the diode cathode are connected to the first sampling resistor, The first sampling resistor is connected to the emitter of the triode, the collector of the triode is connected to one end of the second sampling resistor and the input end of the error amplifier of the PWM controller, and the other end of the second sampling resistor is grounded; the base of the triode is connected to the One end of the third sampling resistor is connected, and the other end of the third sampling resistor is input with a positive voltage; the floating positive voltage output end is drawn from the connection point of the output capacitor and the cathode of the diode. The utility model utilizes the triode current amplification function to realize the sampling feedback of the output voltage, and the magnitude of the output voltage will not be affected by the precision of the resistance, the circuit structure is simple, the cost is low, and the output precision is high.

一种正转正电源电压反馈电路A forward-to-positive power supply voltage feedback circuit

技术领域 technical field

本实用新型涉及一种正转正电源电压反馈电路。  The utility model relates to a forward-to-positive power supply voltage feedback circuit. the

背景技术 Background technique

现代电子系统中，需要得到一些浮地的电压，其需求电压参考地不为输入地，而是输入正电压，见图1。 In modern electronic systems, it is necessary to obtain some floating voltages. The reference ground of the required voltage is not the input ground, but the input positive voltage, as shown in Figure 1.

就正转正电压转换器而言，目前实现该电压转换下的电压采样反馈有如下两种方式。 As far as the forward-to-positive voltage converter is concerned, there are currently two ways to realize the voltage sampling feedback under the voltage conversion as follows.

一是直接将输出电压进行电阻分压，该电压能稳住输出电压，但是对于浮地电压的应用场合，其输出电压（Vout-Vin）受输入电压影响，可应用于前级电压稳定的场合，见图1。 One is to directly divide the output voltage by resistance, which can stabilize the output voltage, but for the application of floating voltage, the output voltage (Vout-Vin) is affected by the input voltage, which can be applied to the occasion where the previous voltage is stable ,see picture 1.

二是Buck-Boost电路电压反馈方式,利用隔离光耦直接将输出电压反馈至输入控制器,通过选取合适传输比的光耦N1,以及配置相应阻值的电阻即可实现对输出电压的调节，见图2。 The second is the Buck-Boost circuit voltage feedback method. The output voltage is directly fed back to the input controller by using the isolated optocoupler. By selecting the optocoupler N1 with a suitable transmission ratio and configuring the resistor with the corresponding resistance value, the output voltage can be adjusted. See Figure 2.

图1所示电路为需要的正转正电路拓扑，但其反馈直接将输出电压经过电阻分压后送入控制器，这种方式无法正确反应Vin与Vout之间的电压差，即无法正常反应浮地电压的大小, Vout的值始终为一确定的输出电压,而输入电压Vin为一变化的电压值,两者的电压差随着Vin的变化而变化,可能造成需要浮地电压的电路的不工作。 The circuit shown in Figure 1 is the required forward-to-positive circuit topology, but its feedback directly sends the output voltage to the controller after being divided by resistors. This method cannot correctly reflect the voltage difference between Vin and Vout, that is, it cannot properly respond to floating. The value of Vout is always a certain output voltage, while the input voltage Vin is a variable voltage value. The voltage difference between the two changes with the change of Vin, which may cause abnormalities in circuits that require floating voltage. Work.

图2的电路反馈方式复杂，光耦CTR受温度影响较大，且需要计算输入侧及输出侧电阻值，电阻精度会影响输出电压的大小，成本高，精度差。  The feedback mode of the circuit in Figure 2 is complex. The CTR of the optocoupler is greatly affected by temperature, and the resistance values of the input side and the output side need to be calculated. The resistance accuracy will affect the output voltage, and the cost is high and the accuracy is poor. the

发明内容 Contents of the invention

本实用新型所要解决的技术问题是，针对上述现有技术的不足，提供一种电源电压反馈电路。 The technical problem to be solved by the utility model is to provide a power supply voltage feedback circuit for the above-mentioned deficiencies in the prior art.

为解决上述技术问题，本实用新型所采用的技术方案是：一种电源电压反馈电路，包括输入储能滤波电容、BOOST升压电路和PWM控制器；所述BOOST升压电路包括电感、二极管、MOS开关管和输出电容，所述电感与所述二极管阳极连接，所述二极管阴极与所述输出电容一端连接，所述输出电容另一端输入正电压；所述MOS开关管的源极接入所述电感与所述二极管阳极之间，所述MOS管的漏极接地，所述MOS管的栅极接所述PWM控制器的驱动单元；所述输入储能滤波电容一端、电感均输入正电压；所述输入储能滤波电容另一端接地；所述输出电容、二极管阴极的连接点与第一采样电阻连接，所述第一采样电阻与三极管发射极连接，所述三极管集电极与第二采样电阻一端、PWM控制器的误差放大器输入端连接，所述第二采样电阻另一端接地；所述三极管基极与第三采样电阻一端连接，所述第三采样电阻另一端输入正电压；浮地正电压输出端自所述输出电容、二极管阴极的连接点引出。 In order to solve the above-mentioned technical problems, the technical solution adopted in the utility model is: a power supply voltage feedback circuit, including an input energy storage filter capacitor, a BOOST boost circuit and a PWM controller; the BOOST boost circuit includes an inductor, a diode, MOS switch tube and output capacitor, the inductor is connected to the anode of the diode, the cathode of the diode is connected to one end of the output capacitor, and the other end of the output capacitor inputs a positive voltage; the source of the MOS switch tube is connected to the Between the inductor and the anode of the diode, the drain of the MOS transistor is grounded, and the gate of the MOS transistor is connected to the drive unit of the PWM controller; one end of the input energy storage filter capacitor and the inductor both input a positive voltage The other end of the input energy storage filter capacitor is grounded; the connection point of the output capacitor and the cathode of the diode is connected to the first sampling resistor, the first sampling resistor is connected to the emitter of the triode, and the collector of the triode is connected to the second sampling One end of the resistor is connected to the input end of the error amplifier of the PWM controller, and the other end of the second sampling resistor is grounded; the base of the triode is connected to one end of the third sampling resistor, and the other end of the third sampling resistor is input with a positive voltage; The positive voltage output terminal is drawn from the connection point of the output capacitor and the cathode of the diode.

与现有技术相比，本实用新型所具有的有益效果为：本实用新型可以得到稳定的浮地正电压，浮地正电压以输入正线为参考地，与输入正电压保持恒定电压差；本实用新型利用三极管电流放大功能，实现了输出电压采样反馈，且输出电压大小不会受到电阻精度的影响，电路结构简单，成本低，输出精度高。 Compared with the prior art, the utility model has the beneficial effects that: the utility model can obtain a stable floating positive voltage, and the floating positive voltage takes the input positive line as a reference ground, and maintains a constant voltage difference with the input positive voltage; The utility model utilizes the current amplification function of the triode to realize the sampling feedback of the output voltage, and the magnitude of the output voltage will not be affected by the precision of the resistance, the circuit structure is simple, the cost is low, and the output precision is high.

附图说明 Description of drawings

图1为直接利用电阻分压的电压反馈电路； Figure 1 is a voltage feedback circuit that directly uses resistor voltage division;

图2为利用线性光耦的电压反馈电路； Figure 2 is a voltage feedback circuit using a linear optocoupler;

图3为本实用新型一实施例电路原理图。 Fig. 3 is a schematic circuit diagram of an embodiment of the utility model.

具体实施方式 detailed description

如图3所示，本实用新型一实施例包括输入储能滤波电容C1、BOOST升压电路和PWM控制器；所述BOOST升压电路包括电感L1、二极管D1、MOS开关管V1和输出电容C2，所述电感L1与所述二极管D1阳极连接，所述二极管阴极D1与所述输出电容C2一端连接，所述输出电容另一端输入正电压Vin；所述MOS开关管的源极接入所述电感与所述二极管阳极之间，所述MOS管的漏极接地，所述MOS管的栅极接所述PWM控制器的驱动单元；所述输入储能滤波电容一端、电感均输入正电压Vin；所述输入储能滤波电容另一端接地；所述输出电容、二极管阴极的连接点与第一采样电阻R1连接，所述第一采样电阻与三极管发射极V2连接，所述三极管集电极与第二采样电阻R2一端、PWM控制器的误差放大器输入端FB连接，所述第二采样电阻R2另一端接地；所述三极管基极与第三采样电阻R4一端连接，所述第三采样电阻R4另一端输入正电压Vin；浮地正电压输出端Vout自所述输出电容、二极管阴极的连接点引出。 As shown in Figure 3, an embodiment of the utility model includes an input energy storage filter capacitor C1, a BOOST boost circuit and a PWM controller; the BOOST boost circuit includes an inductor L1, a diode D1, a MOS switch tube V1 and an output capacitor C2 , the inductor L1 is connected to the anode of the diode D1, the diode cathode D1 is connected to one end of the output capacitor C2, and the other end of the output capacitor inputs a positive voltage Vin; the source of the MOS switch tube is connected to the Between the inductor and the anode of the diode, the drain of the MOS transistor is grounded, and the gate of the MOS transistor is connected to the drive unit of the PWM controller; one end of the input energy storage filter capacitor and the inductor both input positive voltage Vin The other end of the input energy storage filter capacitor is grounded; the connection point of the output capacitor and the cathode of the diode is connected to the first sampling resistor R1, the first sampling resistor is connected to the triode emitter V2, and the triode collector is connected to the first sampling resistor R1. One end of the two sampling resistor R2 is connected to the error amplifier input terminal FB of the PWM controller, and the other end of the second sampling resistor R2 is grounded; the base of the triode is connected to one end of the third sampling resistor R4, and the third sampling resistor R4 is connected to the other end. A positive voltage Vin is input to one end; a floating positive voltage output terminal Vout is drawn from the connection point of the output capacitor and the cathode of the diode.

MOS开关管V1导通时，输入电压为电感L1充电，电流从电感L1流入V1，负载由C2供电；当V1关断时，电流从电感通过D1输送给C2及负载；PWM控制器U1根据输出电压反馈信号，调节开关管驱动脉冲的占空比，维持输出电压的稳定；其“Pulse”端为驱动器脉冲输出端，“FB”为内部误差放大器的输入端，“COMP”为误差放大器的输出端；三极管V2与电阻R1、R2构成输出电压采样反馈电路，R1两端电压的大小反应了输出电压与输入电压之间的压差大小，进而影响Ie的大小，反应至R2两端的电压大小，即FB电压大小。 When the MOS switch tube V1 is turned on, the input voltage charges the inductor L1, the current flows from the inductor L1 into V1, and the load is powered by C2; when V1 is turned off, the current is delivered from the inductor to C2 and the load through D1; the PWM controller U1 according to the output The voltage feedback signal adjusts the duty cycle of the switching tube driving pulse to maintain the stability of the output voltage; its "Pulse" terminal is the driver pulse output terminal, "FB" is the input terminal of the internal error amplifier, and "COMP" is the output of the error amplifier terminal; transistor V2 and resistors R1 and R2 form an output voltage sampling feedback circuit, and the voltage across R1 reflects the voltage difference between the output voltage and the input voltage, which in turn affects the size of Ie, which is reflected in the voltage across R2. That is, the FB voltage.

该电源需要得到的输出浮地电压为Vout与Vin电压差。 The output floating ground voltage required by the power supply is the voltage difference between Vout and Vin.

控制器U1的内部误差放大器输入端为FB，其参考电压为Vref，FB端口电压即为电阻R2上的电压，得： The input terminal of the internal error amplifier of the controller U1 is FB, and its reference voltage is Vref. The voltage at the FB port is the voltage on the resistor R2, and we get:

      PNP三极管V2的基极电压为Vb： The base voltage of PNP transistor V2 is Vb:

      则V2的发射极电压（考虑射基极压降为Veb）： Then the emitter voltage of V2 (considering the emitter-base voltage drop as Veb):

由此可得以下等式： From this the following equation can be obtained:

根据三极管特性Ie = Ic +Ib 及电流放大倍数h_FE = Ic/Ib得_: According to the characteristics of the triode Ie = Ic +Ib and the current amplification factor h _FE = Ic/Ib _:

将等式变换后得： After transforming the equation, we get:

该式中，等式左边为需要的正输出浮地电压Vout-Vin；等式右边，Vref为控制器的内部参考电压，h_FE为三极管的共集电极放大倍数，通过配置一定的R1、R2、R4，可以得到需要的输出电压且其值稳定。 In this formula, the left side of the equation is the required positive output floating voltage Vout-Vin; the right side of the equation, Vref is the internal reference voltage of the controller, h _FE is the magnification of the common collector of the triode, by configuring a certain R1, R2 , R4, the required output voltage can be obtained and its value is stable.

本实用新型主要利用三极管电流放大的功能，实现输出电压采样反馈。当输出电压幅值增大（减小），则R1与E极（发射极）之间电压差增大（减小），发射极电流Ie随之增大（减小），集电极电流Ic增大（减小），使电阻R2上电压升高（降低），导致控制器U1内部的误差放大器输入端电压升高（降低），从而减小（增大）开关管V1的占空比，保证输出电压的稳定；同理，输入电压的变化也会引起相应的调节，保持其输出电压差的稳定。  The utility model mainly utilizes the function of triode current amplification to realize output voltage sampling feedback. When the output voltage amplitude increases (decreases), the voltage difference between R1 and the E pole (emitter) increases (decreases), the emitter current Ie increases (decreases), and the collector current Ic increases (decreases). Large (decrease), the voltage on the resistor R2 increases (decreases), which causes the voltage at the input terminal of the error amplifier inside the controller U1 to increase (decrease), thereby reducing (increasing) the duty cycle of the switch tube V1 to ensure The stability of the output voltage; similarly, the change of the input voltage will also cause corresponding adjustments to maintain the stability of the output voltage difference. the

1. rotate forward a positive voltage feedback circuit, comprise input energy storage filter capacitor, BOOST booster circuit and PWM controller; Described BOOST booster circuit comprises inductance, diode, MOS switching tube and output capacitance, and described inductance is connected with described diode anode, and described diode cathode is connected with described output capacitance one end, described output capacitance other end input positive voltage; The source electrode of described MOS switching tube accesses between described inductance and described diode anode, the grounded drain of described metal-oxide-semiconductor, and the grid of described metal-oxide-semiconductor connects the driver element of described PWM controller; Described input energy storage filter capacitor one end, inductance all input positive voltage; Described input energy storage filter capacitor other end ground connection; It is characterized in that, the tie point of described output capacitance, diode cathode is connected with the first sampling resistor, described first sampling resistor is connected with transistor emitter, described transistor collector is connected with the error amplifier input terminal of second sampling resistor one end, PWM controller, described second sampling resistor other end ground connection; Described transistor base is connected with the 3rd sampling resistor one end, described 3rd sampling resistor other end input positive voltage; Floating ground positive voltage output end is drawn from the tie point of described output capacitance, diode cathode.