Novel flyback isolation switch power supply

Abstract

The utility model relates to a novel flyback isolation switch power supply, which comprises a protection circuit, an anti-interference circuit, an RCD peak absorption circuit, a transformer, a control module, a primary side feedback circuit and a secondary side feedback circuit, the input end of the protection circuit is electrically connected with a power supply, and the output end of the protection circuit is electrically connected with the anti-interference circuit and the RCD peak absorption circuit in sequence. The output end of the RCD peak absorption circuit is electrically connected with a primary winding of the transformer, a secondary winding of the transformer is electrically connected with the input end of the secondary side feedback circuit, the output end of the secondary side feedback circuit is electrically connected with the input end of the primary side feedback circuit, and the output end of the primary side feedback circuit is electrically connected with the control module. And the control module is electrically connected with an auxiliary winding of the transformer. A peripheral circuit of a chip in the control module is simplified, an RCD peak absorption circuit is integrated on a primary winding of the transformer and used for stabilizing a voltage peak value, and the whole power supply circuit module is low in cost and high in anti-interference capability.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply, especially to a novel flyback isolation switching power supply. BACKGROUND

[0002] Compared with the traditional power supply, the flyback switching power supply has the characteristics of simple structure, good stability and low cost, so the flyback switching power supply is gradually applied in mobile phone chargers, power adapter and various products. The flyback switching power supply uses negative feedback regulation to make the output voltage tend to the target voltage. In the negative feedback link, the low voltage side voltage is collected and compared with the comparison voltage, and the difference signal obtained by comparison is transmitted to the control chip of the high voltage side to control the switch duty cycle to adjust the output voltage. The internal circuit structure of the current flyback isolation switching power supply is complex, and the power supply control chip peripheral circuit is complicated, which leads to high hardware cost, rising of power module cost, and further affects the market competitiveness of television products. SUMMARY

[0003] Therefore, it is necessary to provide a novel flyback isolation switching power supply aiming at the above problems.

[0004] A novel flyback isolation switching power supply, comprising a protection circuit, an anti-interference circuit, an RCD peak absorption circuit, a transformer, a control module, a primary feedback circuit and a secondary feedback circuit, the input end of the protection circuit is electrically connected with a power supply, the output end of the protection circuit is electrically connected with the anti-interference circuit and the RCD peak absorption circuit in sequence, the output end of the RCD peak absorption circuit is electrically connected with the primary winding of the transformer, the secondary winding of the transformer is electrically connected with the input end of the secondary feedback circuit, the output end of the secondary feedback circuit is electrically connected with the input end of the primary feedback circuit, the output end of the primary feedback circuit is electrically connected with the control module, and the control module is electrically connected with the auxiliary winding of the transformer.

[0005] Preferably, the control module comprises a power supply control chip U1, the 8-pin of the power supply control chip U1 is electrically connected between the anti-interference circuit and the RCD peak absorption circuit, the 1-pin is electrically connected with the negative electrode of the diode D4 and the primary feedback circuit, the positive electrode of the diode D4 is connected with the 3-pin of the auxiliary winding of the transformer after being connected with the resistor R3 in series, the 1-pin of the power supply control chip U1 is electrically connected with the negative electrode of the diode D2 and one end of the capacitor C9 in parallel, and the diode D2 and the capacitor C9 are grounded, the 2-pin of the power supply control chip U1 is electrically connected with the 3-pin of the auxiliary winding of the transformer through the resistor R4, the 2-pin is also grounded through the resistor R9, the 3-pin is used for collecting the output voltage of the primary feedback circuit, the 4-pin is grounded, the 5-pin is electrically connected with the 4-pin of the auxiliary winding of the transformer after being connected with the resistors R7 and R8 in series and being grounded, the 6-pin is electrically connected with the gate electrode of the MOS tube Q1, the source electrode of the MOS tube Q1 is electrically connected between the resistors R7 and R8, and the drain electrode of the MOS tube Q1 is electrically connected with the RCD peak absorption circuit and the 2-pin of the primary winding of the transformer.

[0006] Preferably, the primary feedback circuit comprises an optical coupler D5, the 4-pin of the optical coupler D5 is connected with the 1-pin of the power supply control chip U1, the 3-pin is connected with the 3-pin of the power supply control chip U1 through the resistor R12 and the capacitor C11 connected in parallel, and the 1-pin and the 2-pin of the optical coupler D5 are connected with the output end of the secondary feedback circuit.

[0007] Preferably, the secondary feedback circuit comprises a power reference chip U2, the 3-pin of the power reference chip U2 is grounded, the 1-pin is electrically connected with the 2-pin of the optical coupler D5, and the 1-pin is also connected with the capacitor C10 and the resistor R10 in series and grounded, the 1-pin of the power reference chip U2 is connected with the secondary winding of the transformer after being connected with the resistors R11 and R6 in series, the 1-pin of the optical coupler D5 is electrically connected between the resistors R11 and R6, the 2-pin of the power reference chip U2 is grounded through the resistor R10, and the 2-pin is also connected with the secondary winding of the transformer through the resistor R5 in series.

[0008] Preferably, the RCD peak absorption circuit comprises diodes Dz1 and D2, resistors R1 and capacitor C5, the positive electrode of the diode D2 is electrically connected with the drain electrode of the MOS tube Q1 and the 2-pin of the primary winding of the transformer, the negative electrode of the diode D2 is electrically connected with the resistor R1 and the capacitor C5 connected in parallel and then connected with the 1-pin of the primary winding of the transformer, the negative electrode of the diode Dz1 is electrically connected with the negative electrode of the diode D2, and the positive electrode of the diode Dz1 is electrically connected with the 1-pin of the primary winding of the transformer.

[0009] Preferably, the model of the power supply control chip U1 is UCC28740QDRQ1, the model of the optical coupler D5 is PS2811-1, and the model of the power reference chip U2 is TL431AIDBZR.

[0010] The utility model discloses the beneficial effect lies in: the peripheral circuit of chip in control module has been simplified, and the RCD peak absorption circuit is integrated on the transformer primary winding, is used for flattening voltage peak, and the whole power circuit module cost is low, and the anti -interference ability is strong, is applicable to the use in new energy automobile. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a new type of flyback isolating power supply circuit schematic diagram for one embodiment;

[0012] Figure 2 It is control module circuit schematic diagram;

[0013] Figure 3 It is primary side feedback circuit schematic diagram;

[0014] Figure 4 It is secondary side feedback circuit schematic diagram;

[0015] Figure 5 It is RCD peak absorption circuit schematic diagram. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the specific embodiment of the utility model is explained in detail below. In the following description, a lot of specific details are set forth in order to fully understand the utility model. However, the utility model can be implemented in many other ways different from the description, and those skilled in the art can make similar improvements without departing from the connotation of the utility model, so the utility model is not limited by the following disclosed specific embodiments.

[0017] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there can be a middle element. When an element is considered "electrically connected" to another element, it can be directly electrically connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the utility model belongs. The terms used in the specification of the utility model herein are only for the purpose of describing the specific implementation and are not intended to limit the utility model. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0019] As Figure 1As shown, a new type of flyback isolating power supply, including protection circuit 1, anti-interference circuit 2, RCD peak absorption circuit 3, transformer 4, control module 5, primary feedback circuit 6 and secondary feedback circuit 7, the input of protection circuit 1 is electrically connected with power supply, the output of protection circuit 1 is electrically connected with anti-interference circuit 2 and RCD peak absorption circuit 3 in turn, the output of RCD peak absorption circuit 3 is electrically connected with the primary winding of transformer 4, the secondary winding of transformer 4 is electrically connected with the input of secondary feedback circuit 7, the output of secondary feedback circuit 7 is electrically connected with the input of primary feedback circuit 6, the output of primary feedback circuit 6 is electrically connected with control module 5, and control module 5 is electrically connected with the auxiliary winding of transformer 4. Specifically, in the embodiment, protection circuit 1 integrates fuse F1 and voltage-dependent resistor MOV, fuse F1 can quickly cut off the power output, prevent internal components from burning out due to continuous high current heating, and a rectifier bridge is integrated in protection circuit 1 to prevent reverse connection. Voltage-dependent resistor MOV can respond to overvoltage signals within nanoseconds, quickly clamp the voltage within a safe range, and avoid transient high voltage from damaging semiconductor devices. The anti-interference circuit 2 in the design is an EMS-EMI anti-interference module, which can be used to prevent surge, harmonic and other interference signals in the power grid from entering the power supply system, causing output voltage fluctuations or device damage, and protecting system stability. Ensure that the power supply works stably in a complex electromagnetic environment. RCD peak absorption circuit 3 is used to absorb the peak in the circuit at the moment the switch power supply is turned on. The peak voltage will exceed 300V momentarily, which can prevent the MOS tube in control module 5 from being damaged by transient voltage. Transformer 4 acts as a voltage reducer to reduce the input high-voltage DC to low-voltage DC output. Control module 5, primary feedback circuit 6 and secondary feedback circuit 7 cooperate with each other. When the MOS tube in control module 5 is turned off, the energy of the secondary winding of transformer 4 is released at this time, and the voltage of the auxiliary winding of transformer 4 is in a fixed proportional relationship with the output voltage of the secondary side, which is used for indirect detection of the output voltage. Control module 5 can generate an error signal according to the auxiliary winding voltage signal sampled by primary feedback circuit 6 to adjust the PWM duty cycle, drive the MOS tube, and realize indirect control of the primary voltage signal of transformer 4 and dynamic adjustment of energy transmission.

[0020] As Figures 1 to 3As shown, the control module 5 includes a power supply control chip U1, the 8-pin of the power supply control chip U1 is electrically connected between the anti-interference circuit 2 and the RCD peak absorption circuit 3, the 1-pin is electrically connected with the negative electrode of the diode D4 and the primary side feedback circuit, the positive electrode of the diode D4 is connected with the 3-pin of the auxiliary winding of the transformer 4 after being connected with the resistor R3 in series, the 1-pin of the power supply control chip U1 is electrically connected with the negative electrode of the diode D2 and one end of the capacitor C9 in parallel, and the primary side feedback circuit 6 is powered, the positive electrode of the diode D2 and the other end of the capacitor C9 are grounded, the 2-pin of the power supply control chip U1 is electrically connected with the 3-pin of the auxiliary winding of the transformer 4 through the resistor R4, the 2-pin is also grounded through the resistor R9, the 3-pin is used for collecting the output voltage of the primary side feedback circuit 6, the 4-pin is grounded, the 5-pin is electrically connected with the 4-pin of the auxiliary winding of the transformer 4 after being connected with the resistors R7 and R8 in series and being grounded, the 6-pin is electrically connected with the gate electrode of the MOS tube Q1, the source electrode of the MOS tube Q1 is electrically connected between the resistors R7 and R8, and the drain electrode of the MOS tube Q1 is electrically connected with the RCD peak absorption circuit 3 and the 2-pin of the primary winding of the transformer 4. Specifically, the 8-pin of the power supply control chip U1 is used as a high-voltage pin, the 2-pin is divided by the voltage dividing resistor R4, and the signal of the auxiliary winding is input. The power supply control chip U1 can calculate the voltage / circuit state of the secondary winding by combining the internal algorithm. At the same time, the auxiliary winding of the transformer 4 is connected with the power supply pin 2-pin of the power supply control chip U1 through the resistor R3 and the diode D4, and the diode D4 can limit the current communication to avoid backflow and prevent the auxiliary winding voltage from burning out the VDD pin of the power supply control chip U1. The 6-pin of the power supply control chip U1 is connected with the gate electrode of the MOS tube, which is used for controlling the conduction of the MOS tube. The power supply control chip U1 adjusts the duty cycle of the PWM signal according to the feedback voltage information of the primary side feedback circuit 6 and the secondary side feedback circuit 7, and then adjusts the conduction time of the MOS tube Q1.

[0021] As shown in Figures 1 to 3 , the primary side feedback circuit 6 includes an optical coupler D5, the 4-pin of the optical coupler D5 is connected with the 1-pin of the power supply control chip U1, the 3-pin is connected with the 3-pin of the power supply control chip U1 through the resistor R12 and the capacitor C11 in parallel, the 1-pin and the 2-pin of the optical coupler D5 are connected with the output end of the secondary side feedback circuit 7. Specifically, when the secondary side feedback circuit 7 inputs the secondary winding voltage and current information of the transformer 4 to the primary side feedback circuit 6 through the linear optical coupler D5, the photoelectric conversion is realized through the optical coupler D5, and then the current signal is input to the power supply control chip U1 pin to adjust the PWM duty cycle, which can reduce electromagnetic interference, maintain the accuracy of feedback, and ensure safety.

[0022] As shown in Figure 1 , 3As shown in FIGS. 4, the secondary side feedback circuit 7 comprises a power reference chip U2, the 3-pin of the power reference chip U2 is grounded, the 1-pin is electrically connected with the 2-pin of the optocoupler D5, and the 1-pin is also connected with the capacitor C10 and the resistor R10 in series and grounded, the 1-pin of the power reference chip U2 is electrically connected with the secondary winding of the transformer 4 in series with the resistor R11 and the resistor R6, the 1-pin of the optocoupler D5 is electrically connected between the resistor R11 and the resistor R6, the 2-pin of the power reference chip U2 is grounded through the resistor R10 and is also electrically connected with the secondary winding of the transformer 4 in series with the resistor R5. Specifically, on the secondary winding of the transformer 4, a capacitor, a resistor and a diode are integrated to form a spike absorption module for absorbing the voltage spike of the output after voltage reduction, and the voltage after CLC filtering is input into the power reference chip U2 to provide a high-precision and low-drift reference voltage for the optocoupler D5.

[0023] As shown in FIGS. 4, the secondary side feedback circuit 7 comprises a power reference chip U2, the 3-pin of the power reference chip U2 is grounded, the 1-pin is electrically connected with the 2-pin of the optocoupler D5, and the 1-pin is also connected with the capacitor C10 and the resistor R10 in series and grounded, the 1-pin of the power reference chip U2 is electrically connected with the secondary winding of the transformer 4 in series with the resistor R11 and the resistor R6, the 1-pin of the optocoupler D5 is electrically connected between the resistor R11 and the resistor R6, the 2-pin of the power reference chip U2 is grounded through the resistor R10 and is also electrically connected with the secondary winding of the transformer 4 in series with the resistor R5. Specifically, on the secondary winding of the transformer 4, a capacitor, a resistor and a diode are integrated to form a spike absorption module for absorbing the voltage spike of the output after voltage reduction, and the voltage after CLC filtering is input into the power reference chip U2 to provide a high-precision and low-drift reference voltage for the optocoupler D5. Figure 1 5 As shown in FIGS. 4, the secondary side feedback circuit 7 comprises a power reference chip U2, the 3-pin of the power reference chip U2 is grounded, the 1-pin is electrically connected with the 2-pin of the optocoupler D5, and the 1-pin is also connected with the capacitor C10 and the resistor R10 in series and grounded, the 1-pin of the power reference chip U2 is electrically connected with the secondary winding of the transformer 4 in series with the resistor R11 and the resistor R6, the 1-pin of the optocoupler D5 is electrically connected between the resistor R11 and the resistor R6, the 2-pin of the power reference chip U2 is grounded through the resistor R10 and is also electrically connected with the secondary winding of the transformer 4 in series with the resistor R5. Specifically, on the secondary winding of the transformer 4, a capacitor, a resistor and a diode are integrated to form a spike absorption module for absorbing the voltage spike of the output after voltage reduction, and the voltage after CLC filtering is input into the power reference chip U2 to provide a high-precision and low-drift reference voltage for the optocoupler D5.

[0024] Specifically, in the embodiment, the model of the power control chip U1 is UCC28740QDRQ1, the model of the optocoupler D5 is PS2811-1, and the model of the power reference chip U2 is TL431AIDBZR.

[0025] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but it cannot be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the utility model, a number of modifications and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.​

Claims

1. A novel flyback isolating power supply, characterized by: The application relates to a power supply circuit, which comprises a protection circuit, an anti-interference circuit, an RCD peak absorption circuit, a transformer, a control module, a primary feedback circuit and a secondary feedback circuit, wherein the input end of the protection circuit is electrically connected with a power supply, the output end of the protection circuit is electrically connected with the anti-interference circuit and the RCD peak absorption circuit in sequence, the output end of the RCD peak absorption circuit is electrically connected with the primary winding of the transformer, the secondary winding of the transformer is electrically connected with the input end of the secondary feedback circuit, the output end of the secondary feedback circuit is electrically connected with the input end of the primary feedback circuit, the output end of the primary feedback circuit is electrically connected with the control module, and the control module is electrically connected with the auxiliary winding of the transformer.

2. A novel isolated flyback power supply as claimed in claim 1, wherein: The control module comprises a power supply control chip U1, the 8-pin of the power supply control chip U1 is electrically connected between the anti-interference circuit and the RCD peak absorption circuit, the 1-pin is electrically connected with the negative electrode of a diode D4 and the primary feedback circuit, the positive electrode of the diode D4 is connected with the 3-pin of the auxiliary winding of the transformer through a resistor R3 in series, the 1-pin of the power supply control chip U1 is electrically connected with the negative electrode of a diode D2 and one end of a capacitor C9 in parallel, and the diode D2 and the capacitor C9 supply power for the primary feedback circuit, the positive electrode of the diode D2 and the other end of the capacitor C9 are grounded, the 2-pin of the power supply control chip U1 is electrically connected with the 3-pin of the auxiliary winding of the transformer through a resistor R4, the 2-pin is also grounded through a resistor R9, the 3-pin is used for collecting the output voltage of the primary feedback circuit, the 4-pin is grounded, the 5-pin is electrically connected with the 4-pin of the auxiliary winding of the transformer through a resistor R7 and a resistor R8 in series and is grounded, the 6-pin is electrically connected with the gate electrode of a MOS tube Q1, the source electrode of the MOS tube Q1 is electrically connected between the resistor R7 and the resistor R8, and the drain electrode of the MOS tube Q1 is electrically connected with the RCD peak absorption circuit and the 2-pin of the primary winding of the transformer.

3. A novel isolated flyback power supply as claimed in claim 2, wherein: The primary feedback circuit comprises an optical coupler D5, the 4-pin of the optical coupler D5 is connected with the 1-pin of the power supply control chip U1, the 3-pin is connected with the 3-pin of the power supply control chip U1 through a resistor R12 and a capacitor C11 in parallel, the 1-pin and the 2-pin of the optical coupler D5 are connected with the output end of the secondary feedback circuit.

4. A novel isolated flyback power supply as claimed in claim 3, wherein: The secondary feedback circuit comprises a power supply reference chip U2, the 3-pin of the power supply reference chip U2 is grounded, the 1-pin is electrically connected with the 2-pin of the optical coupler D5, and the 1-pin is also connected with the capacitor C10 and the resistor R10 in series and grounded, the 1-pin of the power supply reference chip U2 is connected with the secondary winding of the transformer through the resistor R11 and the resistor R6 in series, the 1-pin of the optical coupler D5 is electrically connected between the resistor R11 and the resistor R6, the 2-pin of the power supply reference chip U2 is grounded through the resistor R10, and the 2-pin is also connected with the secondary winding of the transformer through the resistor R5 in series.

5. A novel isolated flyback power supply as claimed in claim 2, wherein: The RCD peak absorption circuit comprises a diode Dz1, a diode D2, a resistor R1 and a capacitor C5, the positive electrode of the diode D2 is electrically connected with the drain electrode of the MOS tube Q1 and the 2-pin of the primary winding of the transformer, the negative electrode of the diode D2 is electrically connected with the resistor R1 and the capacitor C5 in parallel and then connected with the 1-pin of the primary winding of the transformer, the negative electrode of the diode Dz1 is electrically connected with the negative electrode of the diode D2, and the positive electrode of the diode Dz1 is electrically connected with the 1-pin of the primary winding of the transformer.

6. A novel isolated flyback power supply as claimed in claim 4, wherein: The model of the power control chip U1 is UCC28740QDRQ1, the model of the optocoupler D5 is PS2811-1, and the model of the power reference chip U2 is TL431AIDBZR.

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