Dual-tube flyback switching power supply

Abstract

The application discloses a double-tube flyback switching power supply, and relates to the technical field of switching power supplies, which comprises an input rectification filter circuit, a main control circuit, a switching tube circuit, a flyback transformer circuit and an output rectification filter circuit which are sequentially connected, and a feedback circuit is further connected between the flyback transformer circuit and the main control circuit; the switching tube circuit comprises a transistor Q1 and a transistor Q2; the transistor Q1 and the transistor Q2 constitute a double-tube flyback circuit, and both the transistor Q1 and the transistor Q2 are SiC MOSFETs; the output rectification filter circuit comprises a transistor Q3 and a synchronous rectification control chip U3; the transistor Q3 is a SiC MOSFET; and the synchronous rectification control chip U3 adopts a synchronous rectification circuit structure to rectify the power supply output by the flyback transformer. The application adopts the high-temperature-resistant SiC MOSFET switching device and the double-tube flyback structure, improves the power supply efficiency and reliability under the premise of taking into account the high-temperature-resistant performance.

Description

Technical Field

[0001] This application relates to the field of switching power supply technology, and in particular to a dual-transistor flyback switching power supply. Background Technology

[0002] With the ever-increasing global demand for oil and gas resources and the gradual development of traditional oil and gas resources, oil and gas exploration is gradually expanding into deeper formations and deep waters. In this process, oil and gas exploration equipment must cope with the severe challenges of high formation temperatures. Power supply equipment operating for extended periods in high-temperature environments often suffers a significantly shortened lifespan. To adapt to increasingly higher downhole environmental temperatures, the demand for high-temperature and ultra-high-temperature measurement-while-drilling (MWD) instruments is growing stronger. This requires power supply technology to provide solutions suitable for high-temperature environments, ensuring power supply under extreme conditions.

[0003] However, with current technology, high temperature resistance and power efficiency cannot be simultaneously achieved to some extent. To meet the high temperature requirements of deep underground formations, the current solution is to sacrifice power efficiency. Therefore, the efficiency of power supplies that can currently meet the high temperature requirements is generally low. Utility Model Content

[0004] This application provides a dual-tube flyback switching power supply to solve the problem of low efficiency in existing power supplies that meet high temperature resistance requirements.

[0005] This application provides a dual-transistor flyback switching power supply, including an input rectifier filter circuit, a main control circuit, a switching transistor circuit, a flyback transformer circuit, and an output rectifier filter circuit connected in sequence. A feedback circuit is also connected between the flyback transformer circuit and the main control circuit. The switching transistor circuit includes transistors Q1 and Q2, which constitute a dual-transistor flyback circuit. Both transistors Q1 and Q2 are SiC (silicon carbide) MOSFETs (metal oxide transistors). The output rectifier filter circuit includes transistor Q3 and a synchronous rectification control chip U3. Transistor Q3 is a SiC MOSFET, and the synchronous rectification control chip U3 uses a synchronous rectification circuit structure to rectify the power output from the flyback transformer.

[0006] In one possible implementation, the input rectifier filter circuit includes capacitors C1 and C2, which are connected in parallel with one end connected to the power input terminal and the other end grounded.

[0007] In one possible implementation, the main control circuit includes a main control microcontroller U1, a gate driver U2, a resistor R1, and a capacitor C4. The output drive signal terminal DRV of the main control microcontroller U1 is connected to the high-side drive signal terminal HIN of the gate driver U2, and the output drive signal terminal DRV of the main control microcontroller U1 is connected to the low-side drive signal terminal LIN of the gate driver U2 through a delay circuit composed of resistor R1 and capacitor C4.

[0008] In one possible implementation, the switching transistor circuit further includes resistors R3 and R5 and capacitor C5. The source of transistor Q2 is connected to the drain of transistor Q1. The source of transistor Q1 is connected to the parallel resistors R3 and C5. Resistor R3 and capacitor C5 are connected in parallel to the input rectifier filter circuit. The gate of transistor Q1 is connected to the high-side gate drive output terminal HO of gate driver U2. The gate of transistor Q2 is connected to the low-side gate drive output terminal LO of gate driver U2. The drain of transistor Q2 is grounded through resistor R5.

[0009] In one possible implementation, the flyback transformer circuit includes a primary coil winding T1, an auxiliary coil winding T2, a secondary coil winding T3, and an inductor L1. One end of the primary coil winding T1 is connected to the input rectifier and filter circuit, and the other end of the primary coil winding T1 is connected to the inductor L1. The inductor L1 is connected to the drain of transistor Q1 and the source of transistor Q2. The auxiliary coil winding T2 is connected to the feedback circuit, and the secondary coil winding T3 is connected to the output rectifier and filter circuit.

[0010] In one possible implementation, the feedback circuit includes a diode D1, resistors R2, R4, and R6, and a capacitor C6. Terminal 3 of the auxiliary coil winding T2 is connected to the anode of diode D1. The cathode of diode D1 is connected to one end of resistor R2. The other end of resistor R2 is connected to the voltage feedback terminal FB of the main control microcontroller U1. The cathode of diode D1 is also connected to one end of resistor R6. The other end of resistor R6 is connected to the input voltage port of the main control microcontroller U1 and the input voltage port of the gate driver U2. The other end of resistor R6 is also connected to one end of capacitor C6. The other end of capacitor C6 is connected to terminal 4 of the auxiliary coil winding T2. Terminal 4 of the auxiliary coil winding T2 is connected to one end of resistor R4. The other end of resistor R4 is connected to the current feedback terminal CS of the main control microcontroller U1.

[0011] In one possible implementation, the output rectifier filter circuit further includes a capacitor C7 and a resistor R7. The source of transistor Q3 is connected to terminal 5 of the secondary coil winding T3, the gate of transistor Q3 is connected to the output drive signal terminal VG of the synchronous rectification control chip U3, and the drain of transistor Q3 is connected to the output filter circuit, which is composed of a capacitor C7 and a resistor R7 connected in parallel.

[0012] In one possible implementation, the input rectifier filter circuit, main control circuit, switching transistor circuit, flyback transformer circuit, output rectifier filter circuit, and feedback circuit are all mounted on a PCB (printed circuit board), which is made of alumina ceramic.

[0013] The dual-transistor flyback switching power supply of this application has the following advantages:

[0014] The switching circuit uses high-temperature resistant SiC MOSFET switching devices with a dual-transistor flyback structure to achieve a wide input voltage range, improving conversion efficiency and withstand voltage. The output rectifier and filter circuit uses SiC MOSFETs to achieve synchronous rectification, thereby improving efficiency and reliability and reducing ripple. The switching power supply of this application can ensure stable operation in a high-temperature environment of 175°C while achieving an efficiency of 89%. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a functional block diagram of a dual-transistor flyback switching power supply provided in an embodiment of this application.

[0017] Figure 2 The circuit diagram of a dual-transistor flyback switching power supply provided in this application embodiment is shown. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Figure 1-2This application provides a functional block diagram and circuit diagram of a dual-transistor flyback switching power supply. The dual-transistor flyback switching power supply includes an input rectifier and filter circuit, a main control circuit, a switching transistor circuit, a flyback transformer circuit, and an output rectifier and filter circuit connected in sequence. A feedback circuit is also connected between the flyback transformer circuit and the main control circuit. The switching transistor circuit includes transistors Q1 and Q2, which constitute a dual-transistor flyback circuit. Both transistors Q1 and Q2 are SiC MOSFETs. The output rectifier and filter circuit includes transistor Q3 and a synchronous rectification control chip U3. Transistor Q3 is a SiC MOSFET, and the synchronous rectification control chip U3 uses a synchronous rectification circuit structure to rectify the power output from the flyback transformer.

[0020] For example, silicon, as the mainstream semiconductor material for power devices, is widely used due to its relatively excellent high-temperature resistance, radiation resistance, low cost, and huge reserves. SiC, as one of the representatives of third-generation wide-bandgap semiconductor materials, has shown even better high-temperature resistance.

[0021] In traditional feedback circuits, optocouplers are often used as feedback devices. However, optocouplers are prone to current transfer ratio deviation and response speed decrease at high temperatures. At the same time, high temperatures also accelerate the aging of internal materials, shortening the device's lifespan. Therefore, the feedback circuit in this application adopts primary-side feedback, reducing the use of optocouplers and improving the reliability and lifespan of the power supply.

[0022] Furthermore, traditional rectifier circuits often use rectifier diodes, which generate heat during operation. Prolonged operation at high temperatures can lead to reduced conductivity, increased forward voltage drop, and consequently, decreased power efficiency. This application employs synchronous rectification, using high-temperature resistant SiC MOSFETs to replace traditional rectifier diodes to achieve the rectification function. This significantly improves power conversion efficiency and reliability, reduces power loss, and lowers noise and ripple.

[0023] In the embodiments of this application, the input rectifier filter circuit includes capacitor C1 and capacitor C2, which are connected in parallel with one end connected to the power input terminal P1 and the other end grounded.

[0024] Furthermore, the main control circuit includes a main control microcontroller U1, a gate driver U2, a resistor R1, and a capacitor C4. The output drive signal terminal DRV of the main control microcontroller U1 is connected to the high-side drive signal terminal HIN of the gate driver U2. The output drive signal terminal DRV of the main control microcontroller U1 is connected to the low-side drive signal terminal LIN of the gate driver U2 through a delay circuit composed of resistor R1 and capacitor C4.

[0025] In the embodiments of this application, the main control microcontroller U1 is an STM32 series, and the gate driver U2 is a UCC27201.

[0026] The switching transistor circuit also includes resistors R3 and R5 and capacitor C5. The source of transistor Q2 is connected to the drain of transistor Q1. The source of transistor Q1 is connected to the parallel resistor R3 and capacitor C5. Resistor R3 and capacitor C5 are connected in parallel to the input rectifier filter circuit. The gate of transistor Q1 is connected to the high-side gate drive output terminal HO of gate driver U2. The gate of transistor Q2 is connected to the low-side gate drive output terminal LO of gate driver U2. The drain of transistor Q2 is grounded through resistor R5.

[0027] In the embodiments of this application, the main control microcontroller U1 controls the asynchronous switching of transistors Q1 and Q2 through a delay circuit composed of resistor R1 and capacitor C4, which reduces the voltage stress on a single transistor, increases the reliability and withstand voltage of the power supply, and makes the input voltage range wider.

[0028] The flyback transformer circuit includes a primary coil winding T1, an auxiliary coil winding T2, a secondary coil winding T3, and an inductor L1. One end of the primary coil winding T1 is connected to the input rectifier and filter circuit, and the other end of the primary coil winding T1 is connected to the inductor L1. The inductor L1 is connected to the drain of transistor Q1 and the source of transistor Q2. The auxiliary coil winding T2 is connected to the feedback circuit, and the secondary coil winding T3 is connected to the output rectifier and filter circuit.

[0029] In the embodiments of this application, the primary coil winding T1 is used to store energy during the conduction of transistor Q1 or Q2, the auxiliary coil winding T2 is used to provide input voltage and feedback signal to the main control microcontroller U1 and the gate driver U2, and the secondary coil winding T3 is used to transfer energy during the turn-off of transistor Q3.

[0030] The feedback circuit includes diode D1, resistors R2, R4, and R6, and capacitor C6. Terminal 3 of the auxiliary coil winding T2 is connected to the positive terminal of diode D1. The negative terminal of diode D1 is connected to one end of resistor R2. The other end of resistor R2 is connected to the voltage feedback terminal FB of the main control microcontroller U1. The negative terminal of diode D1 is also connected to one end of resistor R6. The other end of resistor R6 is connected to the input voltage port of the main control microcontroller U1 and the input voltage port of the gate driver U2. The other end of resistor R6 is also connected to one end of capacitor C6. The other end of capacitor C6 is connected to terminal 4 of the auxiliary coil winding T2. Terminal 4 of the auxiliary coil winding T2 is connected to one end of resistor R4. The other end of resistor R4 is connected to the current feedback terminal CS of the main control microcontroller U1.

[0031] The output rectifier and filter circuit also includes capacitor C7 and resistor R7. The source of transistor Q3 is connected to terminal 5 of the secondary coil winding T3, the gate of transistor Q3 is connected to the output drive signal terminal VG of the synchronous rectification control chip U3, and the drain of transistor Q3 is connected to the output filter circuit, which consists of capacitor C7 and resistor R7 connected in parallel. The heat loss of the power output diodes at high frequencies and high currents is a significant part of the power supply efficiency loss. Using synchronous rectification can significantly reduce this power consumption, improving system efficiency by more than 1%.

[0032] In the embodiments of this application, the synchronous rectification control chip U3 is model IR11672. This application uses a high-temperature resistant SiC MOSFET instead of a traditional rectifier diode. The forward voltage drop of a traditional rectifier diode is typically 0.3V-0.7V, while the on-resistance of a SiC MOSFET is approximately 10mΩ. Using a synchronous rectification circuit structure can reduce power loss, reduce reverse recovery loss, reduce noise and ripple, and improve power conversion efficiency and reliability.

[0033] Assuming the flyback transformer circuit has an output voltage of V0, an output current of I0, and an output power of P0, and assuming the power consumption of the synchronous rectification control chip U3 has a relatively small impact on the power supply efficiency, the conduction loss P of the rectifier diode is... loss,D The conduction loss P of transistor Q3 loss,Q The improvement in power efficiency, Δη, can be calculated as follows.

[0034] The conduction loss of the rectifier diode:

[0035] P loss,D =I avg ·V F

[0036] Conduction loss of synchronous rectifier diodes:

[0037] P loss,Q =I rms 2 ·R dson

[0038] Improvement in power efficiency:

[0039]

[0040] Assuming an output voltage V0 of 12V, an output current I0 of 2.5A, a transformer turns ratio of 16:1, and a Schottky diode forward voltage drop V... F The voltage is 0.4V, and the on-resistance R of transistor Q3 is used. dson Taking a 10mΩ flyback transformer circuit as an example, the conduction loss ratio η of the rectifier diode can be estimated. DThe conduction loss of transistor Q3 accounts for 3.3% of the total conduction loss η. Q The efficiency loss is 0.5%, and the improvement in power supply efficiency Δη is 2.8%. This demonstrates that using synchronous rectification instead of traditional diode rectification can effectively reduce rectification losses and improve power supply efficiency.

[0041] Furthermore, the output filter circuit of this application is used to improve the quality of the power supply output, reduce ripple amplitude, improve the dynamic performance of the power supply, reduce unnecessary energy loss, and improve the overall efficiency of the power supply.

[0042] The input rectifier and filter circuit, main control circuit, switching transistor circuit, flyback transformer circuit, output rectifier and filter circuit, and feedback circuit are all mounted on the PCB board, which is made of alumina ceramic.

[0043] In the embodiments of this application, the alumina ceramic material used has a thermal conductivity of 30 W / m·K, which can effectively reduce thermal resistance and reduce heat accumulation on the circuit board. Assuming the thermal resistance is reduced to... Using circuit boards made of alumina ceramic material can reduce power loss caused by insufficient thermal management and improve efficiency.

[0044] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0045] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A dual-transistor flyback switching power supply, characterized in that, The system includes an input rectifier and filter circuit, a main control circuit, a switching transistor circuit, a flyback transformer circuit, and an output rectifier and filter circuit connected in sequence. A feedback circuit is also connected between the flyback transformer circuit and the main control circuit. The switching transistor circuit includes transistors Q1 and Q2, which form a dual-transistor flyback circuit. Both transistors Q1 and Q2 are SiC MOSFETs. The output rectifier and filter circuit includes transistor Q3 and a synchronous rectification control chip U3. Transistor Q3 is a SiC MOSFET, and the synchronous rectification control chip U3 uses a synchronous rectification circuit structure to rectify the power output from the flyback transformer.

2. The dual-transistor flyback switching power supply according to claim 1, characterized in that, The input rectifier and filter circuit includes capacitor C1 and capacitor C2, which are connected in parallel with one end connected to the power input terminal and the other end grounded.

3. The dual-transistor flyback switching power supply according to claim 1, characterized in that, The main control circuit includes a main control microcontroller U1, a gate driver U2, a resistor R1, and a capacitor C4. The output drive signal terminal DRV of the main control microcontroller U1 is connected to the high-side drive signal terminal HIN of the gate driver U2. The output drive signal terminal DRV of the main control microcontroller U1 is connected to the low-side drive signal terminal LIN of the gate driver U2 through a delay circuit composed of the resistor R1 and the capacitor C4.

4. A dual-transistor flyback switching power supply according to claim 3, characterized in that, The switching transistor circuit also includes resistors R3 and R5 and capacitor C5. The source of transistor Q2 is connected to the drain of transistor Q1. The source of transistor Q1 is connected to the parallel resistors R3 and C5. Resistor R3 and capacitor C5 are connected in parallel to the input rectifier filter circuit. The gate of transistor Q1 is connected to the high-side gate drive output terminal HO of the gate driver U2. The gate of transistor Q2 is connected to the low-side gate drive output terminal LO of the gate driver U2. The drain of transistor Q2 is grounded through resistor R5.

5. A dual-transistor flyback switching power supply according to claim 3, characterized in that, The flyback transformer circuit includes a primary coil winding T1, an auxiliary coil winding T2, a secondary coil winding T3, and an inductor L1. One end of the primary coil winding T1 is connected to the input rectifier and filter circuit, and the other end of the primary coil winding T1 is connected to the inductor L1. The inductor L1 is connected to the drain of transistor Q1 and the source of transistor Q2. The auxiliary coil winding T2 is connected to the feedback circuit, and the secondary coil winding T3 is connected to the output rectifier and filter circuit.

6. A dual-transistor flyback switching power supply according to claim 5, characterized in that, The feedback circuit includes a diode D1, resistors R2, R4, and R6, and a capacitor C6. Terminal 3 of the auxiliary coil winding T2 is connected to the anode of diode D1. The cathode of diode D1 is connected to one end of resistor R2. The other end of resistor R2 is connected to the voltage feedback terminal FB of the main control microcontroller U1. The cathode of diode D1 is also connected to one end of resistor R6. The other end of resistor R6 is connected to the input voltage port of the main control microcontroller U1 and the input voltage port of the gate driver U2. The other end of resistor R6 is also connected to one end of capacitor C6. The other end of capacitor C6 is connected to terminal 4 of the auxiliary coil winding T2. Terminal 4 of the auxiliary coil winding T2 is connected to one end of resistor R4. The other end of resistor R4 is connected to the current feedback terminal CS of the main control microcontroller U1.

7. A dual-transistor flyback switching power supply according to claim 5, characterized in that, The output rectifier filter circuit also includes a capacitor C7 and a resistor R7. The source of the transistor Q3 is connected to terminal 5 of the secondary coil winding T3. The gate of the transistor Q3 is connected to the output drive signal terminal VG of the synchronous rectification control chip U3. The drain of the transistor Q3 is connected to the output filter circuit. The output filter circuit is composed of the capacitor C7 and the resistor R7 connected in parallel.

8. A dual-transistor flyback switching power supply according to claim 1, characterized in that, The input rectifier filter circuit, the main control circuit, the switching transistor circuit, the flyback transformer circuit, the output rectifier filter circuit, and the feedback circuit are all mounted on a PCB board, which is made of alumina ceramic.

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