Circuit for reducing large dynamic voltage drop output by switching power supply

Abstract

The utility model discloses a circuit for reducing large dynamic voltage drop output by a switching power supply in the field of switching power supply circuit design, which comprises a voltage detection circuit, a signal amplification circuit and a switching control circuit, the second input end of the voltage detection circuit is connected with preset reference voltage, the output end of the voltage detection circuit is connected with the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected with the input end of the switch control circuit, and the output end of the switch control circuit is connected with the single chip microcomputer. The switching power supply solves the problems that a power supply loop of an existing switching power supply is unstable, power supply miniaturization and cost reduction and efficiency improvement are not facilitated, the phenomenon of large dynamic voltage drop output by the switching power supply in a PWM control mode is reduced, only a small number of components need to be added to optimize the output voltage stabilization characteristic during large-range sudden change of a load, an output filter capacitor does not need to be increased, and the switching power supply is simple in structure and low in cost. Cost is saved, and power size space optimization is facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply circuit design, specifically, it relates to a circuit for reducing large dynamic voltage drop of switching power supply output. BACKGROUND

[0002] Switching power supply plays a vital role in modern electronic equipment, especially in those application scenarios that need to handle large range of load mutations. Such switching power supply not only needs to meet the basic power conversion demand, but also must have the ability to maintain the stability of output voltage when the load changes sharply. Specifically, such power supply needs to meet the following two key requirements: first, it can adapt to the large range of load mutations, ensuring stable operation under various load conditions; second, when the load mutates, the fluctuation of output voltage should be controlled within a very small range to ensure the normal operation of the rear-end circuit or device.

[0003] In order to achieve the above requirements, the traditional power supply design strategy usually includes two aspects: one is to speed up the control loop to improve the response speed of the power supply, so that it can adjust the output voltage faster to respond to the change of the load, and the other is to increase the output filter capacitor to smooth the fluctuation of the output voltage and reduce the impact of load mutation on the output voltage.

[0004] However, when the control loop is accelerated, the requirement for PCB wiring is also increased accordingly. If the wiring is improper, high-frequency noise and interference may be introduced, which will cause the power supply loop to be unstable, and the instability of the loop will affect the stability of the output voltage, thereby reducing the reliability of the power supply. Secondly, the increase of filter capacitor will occupy more space and weight, which is not conducive to the miniaturization and lightweight design of the power supply, and the cost of the capacitor will also increase accordingly with the increase of the capacity.

[0005] The above defects need to be solved urgently. UTILITY MODEL CONTENTS

[0006] In order to solve the problem of unstable power supply loop of existing switching power supply and not conducive to the miniaturization and cost reduction of the power supply, the utility model provides a heating roller and electroplating equipment.

[0007] The technical scheme of the utility model is as follows:

[0008] A circuit for reducing large dynamic voltage drop of switching power supply output, comprising a voltage detection circuit, a signal amplification circuit and a switch control circuit, the first input end of the voltage detection circuit is connected with the voltage signal converted by the output current, the second input end of the voltage detection circuit is connected with a preset reference voltage, the output end of the voltage detection circuit is connected with the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected with the input end of the switch control circuit, and the output end of the switch control circuit is connected with a single-chip microcomputer.

[0009] According to the utility model, the voltage detection circuit includes resistance R1, resistance R3, one end of resistance R1 is connected with voltage signal converted by output current, the other end of resistance R1 is connected with one end of resistance R2, one end of capacitor C1, first input end of signal amplification circuit respectively, the other end of resistance R2, the other end of capacitor C1 are connected with negative pole end of power supply voltage, one end of resistance R3 is connected with preset reference voltage, the other end of resistance R3 is connected with one end of capacitor C2, one end of resistance R4, second input end of signal amplification circuit respectively, the other end of capacitor C2, the other end of resistance R4 are connected with negative pole end of power supply voltage.

[0010] According to the utility model, the signal amplification circuit includes operational amplifier U1, the power supply positive input end of operational amplifier U1 is connected with the first input end of voltage detection circuit, the power supply negative input end of operational amplifier U1 is connected with the second input end of voltage detection circuit, the power supply positive end of operational amplifier U1 is connected with the positive pole end of power supply voltage, the power supply negative end of operational amplifier U1 is connected with the negative pole end of power supply voltage, the output end of operational amplifier U1 is connected with the input end of switch control circuit.

[0011] According to the utility model, the signal amplification circuit still includes capacitor C3, resistance R5, diode group D1, one end of capacitor C3, one end of resistance R5 are connected with the power supply positive input end of operational amplifier U1, the other end of capacitor C3 is connected with one end of diode group D1, the other end of resistance R5, the other end of diode group D1 are connected with the output end of operational amplifier U1, the input end of switch control circuit respectively.

[0012] According to the utility model, the diode group D1 includes two diodes, two diodes are connected in parallel.

[0013] According to the utility model, the signal amplification circuit still includes resistance R6, one end of resistance R6 is connected with the output end of operational amplifier U1, the input end of switch control circuit, the other end of resistance R6 is connected with the positive pole end of power supply voltage.

[0014] According to the utility model, the switch control circuit includes triode Q1, the B pole of triode Q1 is connected with the output end of signal amplification circuit, the E pole of triode Q1 is connected with the negative pole end of power supply voltage, the C pole of triode Q1 is connected with singlechip.

[0015] According to the utility model, the switch control circuit further includes a resistor R7 and a resistor R8, one end of the resistor R7 is connected with an output end of the signal amplification circuit, the other end of the resistor R7 is connected with one end of the resistor R8 and the B electrode of the triode Q1 respectively, and the other end of the resistor R8 is connected with the negative electrode end of the power supply voltage.

[0016] According to the utility model, the switch control circuit further includes a resistor R9, one end of the resistor R9 is connected with the single-chip microcomputer and the C electrode of the triode Q1 respectively, and the other end of the resistor R9 is connected with the positive electrode end of the power supply voltage.

[0017] According to the utility model, the triode Q1 is an NPN triode.

[0018] According to the utility model, the switch control circuit further includes a resistor R9, one end of the resistor R9 is connected with the single-chip microcomputer and the C electrode of the triode Q1 respectively, and the other end of the resistor R9 is connected with the positive electrode end of the power supply voltage.

[0019] The current detection device detects the output current in real time and converts the output current into a corresponding voltage signal, and the voltage detection circuit compares the voltage signal with a preset reference voltage, so that when the output load suddenly changes, the voltage detection circuit can quickly capture the voltage change, and the signal amplification circuit amplifies the voltage change and transmits the amplified voltage change to the switch control circuit, the switch control circuit quickly adjusts the control signal of the power supply PWM (pulse width modulation) according to the received signal, so as to realize instant adjustment of the output voltage, effectively improve the voltage drop phenomenon of the output voltage, improve the output voltage stabilization performance of the power supply under dynamic load, and enhance the stability of the power supply loop, so that the output voltage drop phenomenon of the PWM control mode of the switch power supply can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a circuit diagram of the utility model;

[0021] Figure 2 It is a circuit diagram of the voltage detection circuit;

[0022] Figure 3 It is a circuit diagram of the signal amplification circuit;

[0023] Figure 4 It is a circuit diagram of the switch control circuit. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical schemes and beneficial effects to be solved by the utility model clearer and more apparent, the utility model will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and not used to limit the utility model.

[0025] As Figure 1 shown, the utility model provides a kind of circuit for reducing switch power output big dynamic pressure drop, including voltage detection circuit, signal amplification circuit, switch control circuit, the first input of voltage detection circuit is connected with the voltage signal N1 converted by output current, the second input of voltage detection circuit is connected with preset reference voltage REF, the output of voltage detection circuit is connected with the input of signal amplification circuit, the output of signal amplification circuit is connected with the input of switch control circuit, the output of switch control circuit is connected with single-chip microcomputer.

[0026] As Figure 2 shown, in the embodiment, voltage detection circuit includes resistance R1, resistance R3, one end of resistance R1 is connected with the voltage signal converted by output current, the other end of resistance R1 is connected with the first input of signal amplification circuit respectively with one end of resistance R2, one end of capacitor C1, the other end of resistance R2, the other end of capacitor C1 are all connected with the negative pole end of power supply voltage, one end of resistance R3 is connected with preset reference voltage, the other end of resistance R3 is connected with the second input of signal amplification circuit respectively with one end of capacitor C2, one end of resistance R4, the other end of capacitor C2, the other end of resistance R4 are all connected with the negative pole end of power supply voltage.Resistance R1 and resistance R2 are voltage dividing resistance, capacitor C1 and capacitor C2 are filter capacitor, output current is converted into voltage signal N1 by current detection device (current transformer or Hall current sensor), is divided by resistance R1, resistance R2 and is filtered by capacitor C1, then is sent to the first input of signal amplification circuit, preset reference voltage REF is divided by resistance R3, resistance R4 and is filtered by capacitor C2, then is sent to the second input of signal amplification circuit.

[0027] As Figure 3As shown, in this embodiment, the signal amplification circuit includes an operational amplifier U1, a capacitor C3, a resistor R5, and a diode group D1. The positive input terminal of the operational amplifier U1 is connected to the first input terminal of the voltage detection circuit, one end of the capacitor C3, and one end of the resistor R5, respectively. That is, the positive input terminal of the operational amplifier U1 is connected to one end of the capacitor C1, resistor R2, resistor R1, one end of the capacitor C3, and one end of the resistor R5, respectively. The negative input terminal of the operational amplifier U1 is connected to the second input terminal of the voltage detection circuit, that is, the negative input terminal of the operational amplifier U1 is connected to the capacitor C2, resistor R4, and resistor R3, respectively. The positive terminal of the operational amplifier U1 is connected to the positive terminal of the supply voltage, and the negative terminal of the operational amplifier U1 is connected to the negative terminal of the supply voltage, respectively. The other end of the capacitor C3 is connected to one end of the diode group D1, and the other end of the resistor R5 and the other end of the diode group D1 are respectively connected to the output terminal of the operational amplifier U1 and the input terminal of the switch control circuit. During operation, the output current is converted into a voltage signal N1 by a current detection device (current transformer or Hall current sensor). The signal is then divided by resistors R1 and R2, filtered by capacitor C1, and sent to the positive input terminal of the operational amplifier U1. The preset reference voltage REF is divided by resistors R3 and R4, filtered by capacitor C2, and then sent to the negative input terminal of the operational amplifier U1. The output terminal of the operational amplifier U1 and its positive input terminal are positively fed back through resistor R5, capacitor C3, and diode group D1, thereby amplifying the signal.

[0028] like Figure 3 As shown, in this embodiment, diode group D1 includes two diodes connected in parallel. Furthermore, the signal amplification circuit also includes resistor R6, which is a current-limiting resistor. One end of resistor R6 is connected to resistor R5, diode group D1, the output terminal of operational amplifier U1, and the input terminal of the switch control circuit, respectively. The other end of resistor R6 is connected to the positive terminal of the power supply voltage.

[0029] like Figure 4As shown in the embodiment, the switch control circuit comprises a transistor Q1, the B pole of the transistor Q1 is connected with the output end of the signal amplification circuit, the E pole of the transistor Q1 is connected with the negative pole end of the power supply voltage, and the C pole of the transistor Q1 is connected with the single-chip microcomputer.In addition, the switch control circuit further comprises resistors R7 and R8, one end of the resistor R7 is connected with the output end of the operational amplifier U1, the other end of the resistor R7 is connected with one end of the resistor R8 and the B pole of the transistor Q1 respectively, and the other end of the resistor R8 is connected with the negative pole end of the power supply voltage.The signal amplified by the operational amplifier U1 is divided by the resistors R7 and R8, thereby controlling the opening and closing of the transistor Q1, and the voltage of the DSP signal of the single-chip microcomputer is controlled.When the output load suddenly changes greatly, the DSP signal voltage will be reversed in the case of a very short delay time, at this time, the control power PWM is suddenly changed, thereby improving the voltage drop and overshoot of the output voltage.Because of the existence of the positive feedback U of the operational amplifier, the output current needs to have a proper current back difference when the DSP signal is reversed, so the power PWM control is not affected in the case of static load of the output load.

[0030] As Figure 4 shown in the embodiment, the switch control circuit further comprises a resistor R9, the resistor R9 is a current-limiting resistor, one end of the resistor R9 is connected with the single-chip microcomputer and the C pole of the transistor Q1 respectively, and the other end of the resistor R9 is connected with the positive pole end of the power supply voltage.In addition, the transistor Q1 is an NPN transistor, of course, in actual design, the model of the transistor Q1 can be designed according to actual needs.

[0031] In the working process of the utility model, the current detection device detects the output current in real time and converts it into a corresponding voltage signal, the voltage detection circuit compares the signal with a preset reference voltage, when the output load suddenly changes greatly, the voltage detection circuit can quickly capture the voltage change, and the change is amplified by the signal amplification circuit and then transmitted to the switch control circuit, the switch control circuit quickly adjusts the control signal of the power PWM (pulse width modulation) according to the received signal, thereby realizing instant regulation of the output voltage, effectively improving the voltage drop phenomenon of the output voltage, improving the output voltage stabilization performance of the power supply in the dynamic load state, enhancing the stability of the power supply loop, thereby reducing the output dynamic voltage drop phenomenon of the PWM control mode switch power supply.In addition, the utility model only needs to add a small number of components, and the output voltage stabilization characteristics in the case of a large range of load mutations can be optimized, without the need to increase the output filter capacitor, thereby saving costs and being beneficial to optimizing the size of the power supply.

[0032] It should be understood that the above description can be improved or changed by those skilled in the art, and all these improvements and changes shall belong to the protection scope of the appended claims of the utility model.

[0033] The utility model discloses has been described exemplarily above in combination with the drawing, obviously the implementation of the utility model patent is not limited by above-mentioned mode, as long as the various improvements of the method concept and technical scheme of the utility model patent are adopted, or the concept and technical scheme of the utility model patent are directly applied to other occasions without improvement, all are within the protection scope of the utility model.

Claims

1. A circuit for reducing large dynamic voltage drop at the output of a switching power supply, characterized in that, The application relates to a voltage detection circuit, a signal amplification circuit and a switch control circuit.

2. The circuit of claim 1, wherein, The voltage detection circuit comprises a resistor R1 and a resistor R3, one end of the resistor R1 is connected with a voltage signal converted by an output current, the other end of the resistor R1 is connected with one end of a resistor R2, one end of a capacitor C1 and a first input end of the signal amplification circuit respectively, the other end of the resistor R2 and the other end of the capacitor C1 are both connected with a negative electrode end of a power supply voltage, one end of the resistor R3 is connected with a preset reference voltage, the other end of the resistor R3 is connected with one end of a capacitor C2, one end of a resistor R4 and a second input end of the signal amplification circuit respectively, the other end of the capacitor C2 and the other end of the resistor R4 are both connected with the negative electrode end of the power supply voltage.

3. The circuit of claim 1, wherein, The signal amplification circuit comprises an operational amplifier U1, a power supply positive input end of the operational amplifier U1 is connected with the first input end of the voltage detection circuit, a power supply negative input end of the operational amplifier U1 is connected with the second input end of the voltage detection circuit, a power supply positive end of the operational amplifier U1 is connected with a positive electrode end of the power supply voltage, a power supply negative end of the operational amplifier U1 is connected with the negative electrode end of the power supply voltage, and an output end of the operational amplifier U1 is connected with an input end of the switch control circuit.

4. The circuit of claim 3, wherein, The signal amplification circuit further comprises a capacitor C3, a resistor R5 and a diode group D1, one end of the capacitor C3 and one end of the resistor R5 are both connected with the power supply positive input end of the operational amplifier U1, the other end of the capacitor C3 is connected with one end of the diode group D1, the other end of the resistor R5 and the other end of the diode group D1 are both connected with the output end of the operational amplifier U1 and the input end of the switch control circuit respectively.

5. The circuit of claim 4, wherein, The diode group D1 comprises two diodes which are connected in parallel.

6. The circuit of claim 4, wherein, The signal amplification circuit further comprises a resistor R6, one end of the resistor R6 is connected with the resistor R5, the diode group D1, the output end of the operational amplifier U1 and the input end of the switch control circuit respectively, and the other end of the resistor R6 is connected with the positive electrode end of the power supply voltage.

7. The circuit of claim 1, wherein, The switch control circuit comprises a triode Q1, a B pole of the triode Q1 is connected with the output end of the signal amplification circuit, an E pole of the triode Q1 is connected with the negative electrode end of the power supply voltage, and a C pole of the triode Q1 is connected with the single-chip microcomputer.

8. The circuit of claim 7, wherein, The switch control circuit further comprises a resistor R7 and a resistor R8, one end of the resistor R7 is connected with the output end of the signal amplification circuit, the other end of the resistor R7 is connected with one end of the resistor R8 and the B electrode of the triode Q1 respectively, and the other end of the resistor R8 is connected with the negative electrode end of the power supply voltage.

9. The circuit of claim 8, wherein, The switch control circuit further comprises a resistor R9, one end of the resistor R9 is connected with the single-chip microcomputer and the C electrode of the triode Q1 respectively, and the other end of the resistor R9 is connected with the positive electrode end of the power supply voltage.

10. The circuit of claim 7, wherein, The triode Q1 is an NPN triode.

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