Flyback loop power supply circuit

Abstract

The invention belongs to the field of switching power supplies, and particularly relates to a flyback loop power supply circuit which comprises a main power module, a feedback loop module and an auxiliary winding power supply module. The main power module is connected with a first winding of a transformer and connected with the feedback loop, one end of the auxiliary winding power supply module is connected with the feedback loop module, the auxiliary winding power supply module is connected with a second winding, and the other end of the feedback loop module is connected with the auxiliary winding power supply module. The auxiliary winding power supply module comprises a diode V20, a capacitor C3, a capacitor C49 and a resistor R8, the positive electrode of the diode V20 is connected with the second winding, the negative electrode of the diode V20 is connected with the capacitor C3, the capacitor C3 is connected with the capacitor C49, and the capacitor C3 is further connected with the resistor R8 in parallel. According to the invention, the influence of output end voltage fluctuation caused by rapid change of an output aluminum electrolytic capacitor ESR value at a low temperature on loop power supply is improved, and the loop performance at the low temperature can be obviously improved.

Description

Technical Field

[0001] The invention belongs to the field of switching power supplies, and in particular relates to a flyback loop power supply circuit. Background Art

[0002] A flyback power supply is a power supply system that uses a resonant circuit to achieve energy conversion and regulation of the power supply. It usually consists of a high-frequency transformer, a resonant capacitor, a resonant inductor, and a switching element (such as a transistor or MOSFET). The main function of a flyback power supply is to convert the input electrical energy into the form of electrical energy required for a specific application.

[0003] In the localization project, the loop characteristics of the flyback power supply will deteriorate sharply as the ambient temperature decreases, and the Bode plot of the system does not meet the requirements. By testing and comparing the capacitance and ESR of capacitors produced by domestic mainstream manufacturers at different ambient temperatures, it is found that the ESR parameters of domestic aluminum electrolytic capacitors will increase significantly as the ambient temperature decreases. Summary of the invention

[0004] The technical problem to be solved by the present invention is to prevent the ESR parameters of domestic aluminum electrolytic capacitors from increasing when the ambient temperature decreases, thereby increasing the output voltage fluctuation. The present application provides a flyback loop power supply circuit.

[0005] A flyback loop power supply circuit, including:

[0006] Main power module, feedback loop module and auxiliary winding power supply module;

[0007] The main power module is connected to the first winding of the transformer, the main power module is also connected to the feedback loop, one end of the auxiliary winding power supply module is connected to the feedback loop module, the auxiliary winding power supply module is also connected to the second winding, and the other end of the feedback loop module is connected to the auxiliary winding power supply module;

[0008] The auxiliary winding power supply module includes a diode V20, a capacitor C3, a capacitor C49 and a resistor R8. The anode of the diode V20 is connected to the second winding, the cathode of the diode V20 is connected to the capacitor C3, the capacitor C3 is connected to the capacitor C49, and the capacitor C3 is also connected in parallel with the resistor R8.

[0009] Optionally, the main power module includes:

[0010] Diode V1, capacitor C6, electrolytic capacitor C2, electrolytic capacitor C4 and inductor L1;

[0011] The positive electrode of the diode V1 is connected to the same-name end of the first winding, the negative electrode of the diode V1 is connected to the capacitor C6, and the other end of the capacitor C6 is connected to the opposite-name end of the first winding;

[0012] The cathode of the diode V1 is also connected to the anode of the electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to the opposite end of the first winding, the electrolytic capacitor C2 is connected to the electrolytic capacitor C4 in parallel, the anode of the electrolytic capacitor C2 is connected to the anode of the electrolytic capacitor C4, the cathode of the electrolytic capacitor C4 is connected to the cathode of the electrolytic capacitor C4, and an inductor L1 is connected in series between the anode of the electrolytic capacitor C2 and the cathode of the electrolytic capacitor C4.

[0013] Optionally, the feedback loop module includes:

[0014] The feedback loop module includes a resistor R22, a resistor R127, a linear optocoupler, a capacitor C45, a resistor R129, a resistor R23, a resistor R21, a capacitor C79, a resistor R131, a resistor R133, a resistor R136 and a voltage stabilizing diode. The resistor R22 is connected to the resistor R127 and the linear optocoupler. The linear optocoupler is connected to the resistor R127 and the capacitor C45 respectively. The capacitor C45 is connected to the resistor R129. The resistor R129 is connected to the resistor R23. , resistor R23 is connected to resistor R21, the other end of resistor R21 is connected to inductor L1, resistor R23 is also connected to capacitor C79, capacitor C79 is connected to resistor R131, resistor R131 is connected to capacitor C83, capacitor C83 is connected to resistor R127 and the cathode of the Zener diode, resistor R131 is also connected to resistor R136, resistor R136 is connected to the anode of the Zener diode, resistor R133 is connected to resistor R136 in parallel, and one end of resistor R133 is grounded.

[0015] Optionally, the output of the main power module is 5V.

[0016] Optionally, one end of the resistor R8 is grounded.

[0017] Optionally, the negative electrode of the electrolytic capacitor C4 is grounded.

[0018] Optionally, the electrolytic capacitor C4 is an aluminum electrolytic capacitor.

[0019] Optionally, the diode V1 is a rectifier diode.

[0020] Optionally, the auxiliary winding power supply module is used to power the feedback loop module.

[0021] Optionally, the voltage regulator diode is a three-terminal adjustable voltage regulator diode.

[0022] The beneficial effects of the present invention are as follows: an auxiliary winding circuit is constructed by the secondary winding of the transformer, the rectifier diode V20, the filter capacitor C3, and the resistor R8, and the upper end of the feedback optocoupler is connected through the power supply resistor R22 to stably supply power to the feedback loop part. Since the power supply loop is not directly connected to the aluminum electrolytic capacitor, the influence of the output terminal voltage fluctuation on the loop power supply caused by the sharp change of the ESR value of the output aluminum electrolytic capacitor at low temperature when the domestic flyback power supply adopts the traditional output terminal voltage for loop power supply can be effectively alleviated, and the loop performance at low temperature can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a conventional flyback power supply circuit of the present invention;

[0024] Figure 2 The present invention is a schematic diagram of a flyback loop power supply circuit. DETAILED DESCRIPTION

[0025] like Figure 1 As shown, the traditional flyback power supply circuit includes:

[0026] Diode V1, capacitor C6, electrolytic capacitor C2, electrolytic capacitor C4 and inductor L1;

[0027] The positive electrode of the diode V1 is connected to the same-name end of the first winding, the negative electrode of the diode V1 is connected to the capacitor C6, and the other end of the capacitor C6 is connected to the opposite-name end of the first winding;

[0028] The cathode of the diode V1 is also connected to the anode of the electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to the opposite end of the first winding, the electrolytic capacitor C2 is connected to the electrolytic capacitor C4 in parallel, the anode of the electrolytic capacitor C2 is connected to the anode of the electrolytic capacitor C4, the cathode of the electrolytic capacitor C4 is connected to the cathode of the electrolytic capacitor C4, and an inductor L1 is connected in series between the anode of the electrolytic capacitor C2 and the cathode of the electrolytic capacitor C4.

[0029] Resistor R22, resistor R127, linear optocoupler, capacitor C45, resistor R129, resistor R23, resistor R21, capacitor C79, resistor R131, resistor R133, resistor R136 and voltage stabilizing diode, resistor R22 is connected to resistor R127 and linear optocoupler, core optocoupler and resistor R127 are connected to capacitor C45, capacitor C45 is connected to resistor R129, resistor R129 is connected to resistor R23, resistor R21 is connected to capacitor C79, resistor R131, resistor R133, resistor R136 and voltage stabilizing diode, resistor R22 is connected to resistor R127 and linear optocoupler, core optocoupler and resistor R127 are connected to capacitor C45, capacitor C45 is connected to resistor R129, resistor R129 is connected to resistor R23, resistor R2 3 is connected to resistor R21, the other end of resistor R21 is connected to inductor L1, resistor R23 is also connected to capacitor C79, capacitor C79 is connected to resistor R131, resistor R131 is connected to capacitor C83, capacitor C83 is connected to resistor R127 and the cathode of Zener diode, resistor R131 is also connected to resistor R136, resistor R136 is connected to the anode of Zener diode, resistor R133 is connected to resistor R136 in parallel, and one end of resistor R133 is grounded.

[0030] The traditional flyback power supply circuit passes through the first winding of the transformer, passes through the rectifier diode, and is filtered through the capacitor C6, and finally charges the electrolytic capacitor to provide power for feedback. In steady-state operation, the smaller the electrolytic capacitor C, the larger the electrolytic capacitor parameter ESR, and the larger the output voltage ripple. At low temperatures, the larger the output voltage fluctuation, the greater it will bring certain interference to the power supply end, affecting the stability of the loop operation. In addition, in order to stabilize the output voltage, a flyback loop power supply circuit is provided.

[0031] like Figure 2 As shown, a flyback loop power supply circuit includes:

[0032] Main power module, feedback loop module and auxiliary winding power supply module;

[0033] The main power module is connected to the first winding of the transformer, the main power module is also connected to the feedback loop, one end of the auxiliary winding power supply module is connected to the feedback loop module, the auxiliary winding power supply module is also connected to the second winding, and the other end of the feedback loop module is connected to the auxiliary winding power supply module;

[0034] The auxiliary winding power supply module includes a diode V20, a capacitor C3, a capacitor C49 and a resistor R8. The anode of the diode V20 is connected to the second winding, the cathode of the diode V20 is connected to the capacitor C3, the capacitor C3 is connected to the capacitor C49, and the capacitor C3 is also connected in parallel with the resistor R8.

[0035] The main power module includes:

[0036] Diode V1, capacitor C6, electrolytic capacitor C2, electrolytic capacitor C4 and inductor L1;

[0037] The positive electrode of the diode V1 is connected to the same-name end of the first winding, the negative electrode of the diode V1 is connected to the capacitor C6, and the other end of the capacitor C6 is connected to the opposite-name end of the first winding;

[0038] The cathode of the diode V1 is also connected to the anode of the electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to the opposite end of the first winding, the electrolytic capacitor C2 is connected to the electrolytic capacitor C4 in parallel, the anode of the electrolytic capacitor C2 is connected to the anode of the electrolytic capacitor C4, the cathode of the electrolytic capacitor C4 is connected to the cathode of the electrolytic capacitor C4, and an inductor L1 is connected in series between the anode of the electrolytic capacitor C2 and the cathode of the electrolytic capacitor C4.

[0039] The feedback loop module includes a resistor R22, a resistor R127, a linear optocoupler, a capacitor C45, a resistor R129, a resistor R23, a resistor R21, a capacitor C79, a resistor R131, a resistor R133, a resistor R136 and a voltage stabilizing diode. The resistor R22 is connected to the resistor R127 and the linear optocoupler. The linear optocoupler is connected to the resistor R127 and the capacitor C45 respectively. The capacitor C45 is connected to the resistor R129. The resistor R129 is connected to the resistor R23. , resistor R23 is connected to resistor R21, the other end of resistor R21 is connected to inductor L1, resistor R23 is also connected to capacitor C79, capacitor C79 is connected to resistor R131, resistor R131 is connected to capacitor C83, capacitor C83 is connected to resistor R127 and the cathode of the Zener diode, resistor R131 is also connected to resistor R136, resistor R136 is connected to the anode of the Zener diode, resistor R133 is connected to resistor R136 in parallel, and one end of resistor R133 is grounded.

[0040] The resistor R8, the cathode of the electrolytic capacitor C4 and the resistor R133 are all grounded.

[0041] In this embodiment, the output voltage is set to 5V, and the parameters of the components in a flyback loop power supply circuit can be: the rectifier diode can be SS36B model, the inductor L1 is 10μH, the capacitor C6 is 4.7μF / 50V, the electrolytic capacitor C2 is 1000μF / 16V, the electrolytic capacitor C4 is 1000μF / 16V, the specification of the diode V20 is 400V / 1A, the capacitor C3 is 2.2μF / 25V, the capacitor C49 is 2.2μF / 16V, the resistor R8 is 3.3KΩ, the resistor R22 and the resistor R21 are 470Ω, and the resistor R127 is 1 000Ω, the capacity of capacitor C45 is 4.7nF / 50V, the resistance of resistor R129 is 47KΩ, the resistance of resistor R23 is 4.7KΩ, the capacity of capacitor C79 is 10nF / 100V, the resistance of resistor R131 is 1000Ω, the capacity of capacitor C83 is 47nF / 50V, the resistance of resistor R36 is 4.7kΩ, and the resistance of resistor R133 is 470K. This embodiment only provides a circuit component parameter when the output voltage is 5V. In actual use, the component parameters are different depending on the output voltage (positive voltage of electrolytic capacitor C4).

[0042] The first winding and the second winding are two windings on the secondary side of the transformer. The rectifier diode V1, the output inductor L1 and the output aluminum electrolytic capacitor C4 constitute the basic structure of the flyback power supply on the secondary side. The resistor R23, the capacitor C79, the resistor R131, the capacitor C45, the resistor R129 and the capacitor C83 constitute a type 3 operational amplifier compensation network. The error signal is fed back to the primary side through the linear optocoupler and the voltage regulator diode V14. The voltage regulator diode can be a TL431 voltage regulator (three-terminal adjustable voltage regulator). When the output voltage changes, the feedback voltage is compared with the voltage reference of TL431, and after correction by the compensation network, the error signal is fed back to the PWM control chip on the primary side through the TL431 and the feedback optocoupler for processing. Finally, the output voltage is stabilized by adjusting the duty cycle of the main power MOS tube on the primary side.

[0043] The auxiliary winding circuit is built with the secondary winding of the transformer, the rectifier diode V20, the filter capacitor C3, and the resistor R8, which is connected to the upper end of the feedback optocoupler through the power supply resistor R22 to provide stable power supply for the feedback loop. Since the power supply loop is not directly connected to the aluminum electrolytic capacitor, it can effectively alleviate the impact of the output voltage fluctuation on the loop power supply caused by the sharp change of the ESR value of the output aluminum electrolytic capacitor at low temperature when the domestic flyback power supply uses the traditional output voltage for loop power supply, and can significantly improve the loop performance at low temperature.

[0044] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as above, which are not provided in detail for the sake of simplicity.

[0045] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A flyback loop power supply circuit, characterized in that: include: Main power module, feedback loop module and auxiliary winding power supply module; The main power module is connected to the first winding of the transformer, the main power module is also connected to the feedback loop, one end of the auxiliary winding power supply module is connected to the feedback loop module, the auxiliary winding power supply module is also connected to the second winding, and the other end of the feedback loop module is connected to the auxiliary winding power supply module; The auxiliary winding power supply module includes a diode V20, a capacitor C3, a capacitor C49 and a resistor R8, the positive electrode of the diode V20 is connected to the second winding, the negative electrode of the diode V20 is connected to the capacitor C3, the capacitor C3 is connected to the capacitor C49, and the capacitor C3 is also connected in parallel with the resistor R8.

2. A flyback loop power supply circuit as claimed in claim 1, characterized in that: The main power module comprises: Diode V1, capacitor C6, electrolytic capacitor C2, electrolytic capacitor C4 and inductor L1; The positive electrode of the diode V1 is connected to the same-name end of the first winding, the negative electrode of the diode V1 is connected to the capacitor C6, and the other end of the capacitor C6 is connected to the opposite-name end of the first winding; The cathode of the diode V1 is also connected to the anode of the electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to the opposite end of the first winding, the electrolytic capacitor C2 is connected in parallel with the electrolytic capacitor C4, the anode of the electrolytic capacitor C2 is connected to the anode of the electrolytic capacitor C4, the cathode of the electrolytic capacitor C4 is connected to the cathode of the electrolytic capacitor C4, and the inductor L1 is connected in series between the anode of the electrolytic capacitor C2 and the cathode of the electrolytic capacitor C4.

3. A flyback loop power supply circuit as claimed in claim 2, characterized in that: The feedback loop module comprises: The feedback loop module includes a resistor R22, a resistor R127, a linear optocoupler, a capacitor C45, a resistor R129, a resistor R23, a resistor R21, a capacitor C79, a resistor R131, a resistor R133, a resistor R136 and a voltage stabilizing diode. The resistor R22 is connected to the resistor R127 and the linear optocoupler. The linear optocoupler is connected to the resistor R127 and the capacitor C45 respectively. The capacitor C45 is connected to the resistor R129. The resistor R129 is connected to the resistor R23. The resistor R23 is connected to the The resistor R21 is connected, the other end of the resistor R21 is connected to the inductor L1, the resistor R23 is also connected to the capacitor C79, the capacitor C79 is connected to the resistor R131, the resistor R131 is connected to the capacitor C83, the capacitor C83 is connected to the resistor R127 and the cathode of the Zener diode, the resistor R131 is also connected to the resistor R136, the resistor R136 is connected to the anode of the Zener diode, the resistor R133 is connected in parallel with the resistor R136, and one end of the resistor R133 is grounded.

4. A flyback loop power supply circuit as claimed in claim 1, characterized in that: include: The output of the main power module is 5V.

5. A flyback loop power supply circuit as claimed in claim 1, characterized in that: include: One end of the resistor R8 is grounded.

6. A flyback loop power supply circuit as claimed in claim 2, characterized in that: include: The negative electrode of the electrolytic capacitor C4 is grounded.

7. A flyback loop power supply circuit as claimed in claim 2, characterized in that: include: The electrolytic capacitor C4 is an aluminum electrolytic capacitor.

8. The flyback loop power supply circuit according to claim 1, characterized in that: include: The diode V1 is a rectifier diode.

9. The flyback loop power supply circuit according to claim 1, characterized in that: include: The auxiliary winding power supply module is used to supply power to the feedback loop module.

10. The flyback loop power supply circuit as claimed in claim 3, characterized in that: include: The voltage regulator diode is a three-terminal adjustable voltage regulator diode.

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