Flyback circuit and electronic device
By using dual flyback power supplies in series for current limiting detection, voltage division, and real-time monitoring, the voltage withstand requirement of the switching transistor is reduced, solving the problem of voltage withstand selection for flyback topologies under high voltage environments, and enabling the widespread application of switching transistors and circuit stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2026-03-10
Smart Images
Figure CN223987041U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] Embodiments of the present application relate to the technical field of electronic circuit, and particularly relate to a flyback circuit and electronic equipment. BACKGROUND
[0002] With the development of new energy to high-voltage platform, such as the battery system of electric vehicles from 400V to 800V, and the direct current end of photovoltaic power station from 1000V to 1500V, more energy, higher efficiency and other advantages are brought, and the loss is also reduced, the system efficiency is improved, the equipment volume and workload are reduced, and the cost is reduced.
[0003] But high voltage also brings challenges to the auxiliary source design of flyback topology, such as higher voltage requiring higher voltage tube, flyback leakage inductance causing tube peak, increasing the difficulty of voltage selection, etc. CONTENT OF THE INVENTION
[0004] Embodiments of the present application provide a flyback circuit and electronic equipment, which can reduce the voltage resistance of the switch tube in the circuit by detecting the current limiting of the double flyback power supply in series, and further make the selection range of the switch tube wider.
[0005] The embodiment of the present application provides a flyback circuit, which comprises a voltage division module, a control module, a driving module, a first flyback module, a second flyback module, a current limiting module, an output module and a feedback module. The voltage division module is used for being connected with an input power supply, and is connected with the first flyback module and the second flyback module. The control module is connected with the voltage division module, the driving module, the current limiting module, the feedback module and the input power supply respectively. The driving module is connected with the first flyback module, the second flyback module and the current limiting module respectively. The current limiting module is connected with the first flyback module and the second flyback module in series. The output module is coupled with the first flyback module and the second flyback module respectively, and is also connected with the feedback module. The voltage division module is used for dividing input voltage of the input power supply to supply power for the first flyback module, the second flyback module, the control module and the feedback module. The control module is used for obtaining working current from the input power supply to start working when the input power supply is powered on, and sending a control signal to the driving module when starting working. The driving module is used for working when receiving the control signal, and outputting a driving signal to make the first flyback module, the second flyback module and the current limiting module work based on the driving signal. The current limiting module is used for generating a to-be-tested voltage when working. The control module is also used for stopping outputting the control signal when the to-be-tested voltage is greater than a preset voltage threshold. The voltage value of the to-be-tested voltage rises with working time. The output module is used for obtaining electric energy from the first flyback module and the second flyback module, and generating an output voltage. The feedback module is used for performing voltage division processing on the output voltage to obtain a feedback voltage. The control module is also used for adjusting duty ratio or frequency of the control signal based on the feedback voltage, and then adjusting duty ratio or frequency of the driving signal output by the driving module.
[0006] In some embodiments, the control module comprises a controller U1, a resistor R1, a resistor R2 and a capacitor C1. A first end of the resistor R1 is connected with the input power supply, a second end of the resistor R1 is connected with a first end of the resistor R2, a second end of the resistor R2 is connected with a power supply end of the controller U1 and a first end of the capacitor C1, a second end of the capacitor C1 is connected with the voltage division module and a ground end of the controller U1 respectively, a voltage reference end of the controller U1 is connected with the feedback module, a signal output end of the controller U1 is connected with the driving module, and a current reference end of the controller U1 is connected with the current limiting module.
[0007] In some embodiments, the current limiting module includes a current transformer CT1, a resistor Rcs1, a resistor Rcs2, a resistor R6, a diode D1, and a diode D2. The first input end and the second input end of the current transformer CT1 are connected in series with the second flyback module, the second output end of the current transformer CT1 is connected with the driving module, the first output end of the current transformer CT1 is connected with the positive electrode of the diode D1 and the negative electrode of the diode D2, the negative electrode of the diode D1 is connected with the first end of the resistor Rcs2 and the control module respectively, the second end of the resistor Rcs2 is connected with the first end of the resistor Rcs1 and the first flyback module respectively, the second end of the resistor Rcs1 is connected with the first end of the resistor R6, the voltage dividing module and the second flyback module respectively, and the second end of the resistor R6 is connected with the positive electrode of the diode D2.
[0008] In some embodiments, the feedback module includes an optocoupler U4, a Zener ZD1, a resistor R5, a resistor R10, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a capacitor C6 and a capacitor C7. The first end of the resistor R5 and the first end of the resistor R13 are connected with the output module, the second end of the resistor R5 is connected with the first end of the resistor R15, the second end of the capacitor C6, the second end of the capacitor C7 and the reference input end of the Zener ZD1 respectively, the second end of the resistor R13 is connected with the first end of the resistor R14 and the first input end of the optocoupler U4 respectively, the second end of the resistor R14 is connected with the first end of the capacitor C6, the first end of the resistor R12, the second input end of the optocoupler U4 and the negative electrode of the Zener ZD1 respectively, the second end of the resistor R12 is connected with the first end of the capacitor C7, the positive electrode of the Zener ZD1 and the second end of the resistor R15 are grounded, the first output end of the optocoupler U4 is connected with the voltage dividing module through the resistor R10, and the second output end of the optocoupler U4 is connected with the control module.
[0009] In some embodiments, the driving module includes a driver U2 and a driver U3. The signal input end of the driver U2 and the signal input end of the driver U3 are connected with the control module, the ground end of the driver U2 and the ground end of the driver U3 are connected with the voltage dividing module, the gate control end of the driver U2 is connected with the first flyback module, the source connection end of the driver U2 is connected with the first flyback module and the current limiting module respectively, the gate control end of the driver U3 is connected with the second flyback module, and the source connection end of the driver U3 is connected with the second flyback module.
[0010] In some embodiments, the first flyback module comprises a transformer winding T1-1, a switch Q1, a resistor R3, a resistor R7, a capacitor C2, a capacitor C3, and a diode D3. A first end of the transformer winding T1-1 is connected to a first end of the resistor R3, a first end of the capacitor C2, the input power supply, and the voltage dividing module, respectively. A second end of the transformer winding T1-1 is connected to a first end of the switch Q1 and a positive electrode of the diode D3, respectively. A negative electrode of the diode D3 is connected to a second end of the resistor R3 and a second end of the capacitor C2, respectively. A control end of the switch Q1 is connected to a first end of the resistor R7, a first end of the capacitor C3, and the driving module, respectively. A second end of the switch Q1 is connected to a second end of the resistor R7, a second end of the capacitor C3, the driving module, and the current limiting module, respectively.
[0011] In some embodiments, the second flyback module comprises a transformer winding T1-2, a switch Q2, a resistor R4, a resistor R8, a capacitor C4, a capacitor C5, and a diode D4. A first end of the transformer winding T1-2 is connected to a first end of the resistor R4, a first end of the capacitor C4, the current limiting module, and the voltage dividing module, respectively. A second end of the transformer winding T1-2 is connected to a first end of the switch Q2 and a positive electrode of the diode D4, respectively. A negative electrode of the diode D4 is connected to a second end of the resistor R4 and a second end of the capacitor C4, respectively. A control end of the switch Q2 is connected to a first end of the resistor R8, a first end of the capacitor C5, and the driving module, respectively. A second end of the switch Q2 is connected to a second end of the resistor R8, a second end of the capacitor C5, the driving module, and the current limiting module, respectively.
[0012] In some embodiments, the voltage dividing module comprises a capacitor CE1 and a capacitor CE2. A positive electrode of the capacitor CE1 is connected to a positive electrode of the input power supply, the control module, and the first flyback module, respectively. A negative electrode of the capacitor CE1 is connected to a positive electrode of the capacitor CE2, the current limiting module, the second flyback module, the control module, the driving module, and the feedback module, respectively. A negative electrode of the capacitor CE2 is connected to a negative electrode of the input power supply and the current limiting module, respectively.
[0013] In some embodiments, the output module includes a transformer winding T1-3, a diode D5, a capacitor CE3, and a resistor R11. The first terminal of the transformer winding T1-3 is connected to the anode of the diode D5, and the cathode of the diode D5 is connected to the anode of the capacitor CE3, the first terminal of the resistor R11, and the feedback module. The second terminal of the transformer winding T1-3, the cathode of the capacitor CE3, and the second terminal of the resistor R11 are all grounded. The cathode of the diode D5 is the output point of the output voltage.
[0014] This application also provides an electronic device, which includes the flyback circuit described above.
[0015] Unlike existing technologies, this application provides a flyback circuit and electronic device. The flyback circuit includes a voltage divider module, a control module, a drive module, a first flyback module, a second flyback module, a current limiting module, an output module, and a feedback module. The input power supply is divided by the voltage divider module to power the two flyback modules (i.e., the first flyback module and the second flyback module), reducing the voltage across each flyback module to half the input voltage (e.g., a 1500V input voltage is divided into 750V), thereby reducing the voltage withstand requirement of the switching transistor. The current limiting module is connected in series with the two flyback modules to form a current detection path. When the drive module outputs a drive signal, the two flyback modules operate synchronously, and the voltage to be measured is generated by the current limiting module. The control module monitors the voltage to be measured in real time. If it exceeds a preset voltage threshold (e.g., due to leakage inductance or voltage fluctuations causing overcurrent, the voltage increases with the current), it immediately stops outputting the control signal, cutting off the drive and preventing damage to the switching transistor due to overvoltage / overcurrent. The feedback module divides the output voltage and feeds it back to the control module. The control module adjusts the duty cycle or frequency of the drive signal to balance the energy distribution of the dual flyback module, ensuring stable bus midpoint voltage and optimizing the operating state of the switching transistors, further reducing the withstand voltage requirement. This application reduces the withstand voltage of the switching transistors in the circuit by using series current limiting detection of the dual flyback power supply, thereby broadening the selection range of switching transistors. Attached Figure Description
[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.
[0017] Figure 1 This is a structural block diagram of the flyback circuit provided in the embodiments of this application;
[0018] Figure 2This is a schematic diagram of the circuit structure of the voltage divider module, control module, drive module, first flyback module, second flyback module, and current limiting module provided in the embodiments of this application;
[0019] Figure 3 This is a schematic diagram of the circuit structure of the output module and the feedback module provided in the embodiments of this application. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0021] The technical features involved in the various embodiments of this application described below do not conflict with each other and can be combined with each other.
[0022] When an element is described as "connected" to another element, it can be directly connected to the other element, or there may be one or more intervening elements between them.
[0023] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more.
[0024] Please see Figure 1 , Figure 1 This is a structural block diagram of the flyback circuit 100 provided in the embodiments of this application.
[0025] The flyback circuit 100 includes a voltage divider module 10, a control module 20, a drive module 30, a first flyback module 40, a second flyback module 50, a current limiting module 60, an output module 70, and a feedback module 80.
[0026] Among them, the voltage divider module 10 is used to connect with the input power supply ( Figure 1 and Figure 2The input power supply includes its positive terminal (BUS+) and negative terminal (BUS-) connected. The voltage divider module 10 is connected to the first flyback module 40 and the second flyback module 50. The control module 20 is connected to the voltage divider module 10, the drive module 30, the current limiting module 60, the feedback module 80, and the input power supply. The drive module 30 is connected to the first flyback module 40, the second flyback module 50, and the current limiting module 60. The current limiting module 60 is connected in series with the first flyback module 40 and the second flyback module 50. The output module 70 is coupled to the first flyback module 40 and the second flyback module 50. The output module 70 is also connected to the feedback module 80.
[0027] Specifically, the voltage divider module 10 divides the input voltage of the input power supply to power the first flyback module 40, the second flyback module 50, the control module 20, and the feedback module 80. The control module 20 obtains operating current from the input power supply to start operation when the input power supply is powered on, and sends a control signal to the drive module 30 upon startup. The drive module 30 operates upon receiving the control signal and outputs a drive signal to enable the first flyback module 40, the second flyback module 50, and the current limiting module 60 to operate based on the drive signal. The current limiting module 60 generates a test voltage during operation; the control module 20 also stops outputting the control signal when the test voltage exceeds a preset voltage threshold; the test voltage increases with operating time. The output module 70 obtains electrical energy from the first flyback module 40 and the second flyback module 50 and generates an output voltage. The feedback module 80 is used to divide the output voltage to obtain the feedback voltage; the control module 20 is also used to adjust the duty cycle (or frequency) of the control signal based on the feedback voltage, thereby adjusting the duty cycle (or frequency) of the drive signal output by the drive module 30.
[0028] The control signal is sent by the control module 20 to the drive module 30 after the input power is turned on and the circuit starts operating. Essentially, it is an electrical signal used to regulate the circuit's operating state, typically appearing as a pulse signal. The drive module 30 determines whether to output a drive signal based on the received control signal, and certain characteristics of the control signal (such as duty cycle or frequency) affect the corresponding characteristics (such as duty cycle or frequency) of the drive signal output by the drive module 30, thereby indirectly controlling the operating states of the first flyback module 40, the second flyback module 50, and the current limiting module 60.
[0029] The drive signal is the signal output by the drive module 30 after receiving the control signal sent by the control module 20. The drive signal is generally an electrical pulse signal with specific parameters (such as idle percentage or frequency). The drive signal is the power source that directly drives the first flyback module 40, the second flyback module 50, and the current limiting module 60. The first flyback module 40 and the second flyback module 50 store and convert energy according to the drive signal, and the current limiting module 60 also starts working and generates the voltage to be measured under the action of the drive signal.
[0030] The voltage to be measured is the voltage generated by the current limiting module 60 during operation. It is a physical quantity that reflects the current operating voltage of the circuit. When the drive module 30 outputs a drive signal to start the first flyback module 40, the second flyback module 50, and the current limiting module 60, a current is generated in the circuit of the current limiting module 60. The current limiting module 60 generates the voltage to be measured based on this current. Furthermore, as the circuit operates for an extended period, the voltage value of the voltage to be measured will increase (essentially, the current in the current limiting module 60 gradually increases).
[0031] The preset voltage threshold is a voltage value pre-set in the control module 20, determined by the circuit parameters of the current limiting module 60 and the preset voltage threshold. It serves as a standard for judging whether an overcurrent condition has occurred in the circuit. When the voltage to be measured generated by the current limiting module 60 exceeds the preset voltage threshold, the control module 20 will detect that the voltage to be measured exceeds the preset voltage threshold. At this time, it is determined that the circuit is in an overcurrent state. To prevent circuit components from being damaged by excessive current, the control module 20 will stop outputting control signals, thereby cutting off the operation of the first flyback module 40, the second flyback module 50, and the current limiting module 60, thus protecting the circuit.
[0032] The output voltage is the voltage generated by the output module 70 after obtaining electrical energy from the first flyback module 40 and the second flyback module 50, and after energy conversion and processing. It is the voltage that the flyback circuit 100 ultimately provides to the external load.
[0033] The feedback voltage is the voltage obtained by the feedback module 80 after dividing the output voltage generated by the output module 70. It is a voltage signal proportional to the output voltage, reflecting the actual output voltage situation. The feedback voltage is fed back to the control module 20, serving as a crucial basis for adjusting the control signal. The control module 20 compares the feedback voltage with the expected voltage value to determine if the output voltage deviates from the set value. If there is a deviation, the control module 20 will adjust the parameters of the control signal (such as duty cycle or frequency) accordingly to achieve precise regulation of the output voltage and maintain its stability.
[0034] Please see Figure 2 , Figure 2This is a schematic diagram of the circuit structure of the voltage divider module 10, control module 20, drive module 30, first flyback module 40, second flyback module 50 and current limiting module 60 provided in the embodiments of this application.
[0035] In some embodiments, the voltage divider module 10 includes capacitors CE1 and CE2. The positive terminal of capacitor CE1 is connected to the control module 20, the first flyback module 40, and the positive terminal BUS+ of the input power supply. The negative terminal of capacitor CE1 is connected to the positive terminal of capacitor CE2, the current limiting module 60, the second flyback module 50, the control module 20, the drive module 30, and the feedback module 80. The negative terminal of capacitor CE2 is connected to the current limiting module 60 and the negative terminal BUS- of the input power supply.
[0036] In some embodiments, the control module 20 includes a controller U1, resistors R1 and R2, and a capacitor C1. The first end of resistor R1 is connected to the input power supply, the second end of resistor R1 is connected to the first end of resistor R2, the second end of resistor R2 is connected to the power supply terminal VCC of controller U1 and the first end of capacitor C1, the second end of capacitor C1 is connected to the voltage divider module 10 and the ground terminal GND of controller U1, the voltage reference terminal COM of controller U1 is connected to the feedback module 80, the signal output terminal DRIVER of controller U1 is connected to the drive module 30, and the current reference terminal CS of controller U1 is connected to the current limiting module 60.
[0037] The controller U1 can be an integrated circuit chip with signal processing and control functions, or any other electronic device capable of performing the same function. It analyzes and judges the input signals (such as the feedback voltage signal from the feedback module 80 and the current signal from the current limiting module 60) and outputs corresponding control signals. Common controllers may include MCUs (Microcontroller Units) or dedicated power management chips. Their function is to regulate the operating state of the entire flyback circuit 100, ensuring stable output voltage and safe circuit operation.
[0038] In some embodiments, the drive module 30 includes a driver U2 and a driver U3. The signal input terminals of both the driver U2 and the driver U3 are connected to the control module 20. The ground terminals M of both the driver U2 and the driver U3 are connected to the voltage divider module 10. The gate control terminal G1 of the driver U2 is connected to the first flyback module 40. The source connection terminal S1 of the driver U2 is connected to both the first flyback module 40 and the current limiting module 60. The gate control terminal G2 of the driver U3 is connected to the second flyback module 50, and the source connection terminal S2 of the driver U3 is connected to the second flyback module 50.
[0039] Specifically, the gate control terminal G1 of driver U2 and the gate control terminal G2 of driver U3 are both gate control terminals. They both quickly charge or discharge the gate capacitance (CGS) of the corresponding MOSFET by outputting high current pulses, thereby changing the gate voltage and causing the switching transistor to quickly enter the on or off state.
[0040] Both the source connection terminal S1 of driver U2 and the source connection terminal S2 of driver U3 are source connection terminals, which are directly connected to the source of the corresponding MOSFET. They are both the end point of the current loop and the reference reference of the gate voltage (VGS must reach the threshold to turn on).
[0041] The signal input terminals of both driver U2 and driver U3 receive control signals from controller U1. These signals are then matched and filtered by the input stage circuit, ultimately driving switches Q1 and Q2 to conduct.
[0042] Drivers U2 and U3 can be power drive chips. Their main function is to amplify the control signal output from the control module 20 to provide sufficient drive capability to drive the switching transistors (Q1 and Q2) in the first flyback module 40 and the second flyback module 50. The drivers can respond quickly to the control signal and accurately control the switching transistors to turn on and off, thereby achieving precise control of the energy conversion process of the first flyback module 40 and the second flyback module 50.
[0043] In some embodiments, the first flyback module 40 includes a transformer winding T1-1, a switching transistor Q1, resistors R3 and R7, capacitors C2 and C3, and a diode D3. The first end of the transformer winding T1-1 is connected to the first end of resistor R3, the first end of capacitor C2, the input power supply, and the voltage divider module 10. The second end of the transformer winding T1-1 is connected to the first end of switching transistor Q1 and the positive terminal of diode D3. The negative terminal of diode D3 is connected to the second end of resistor R3 and the second end of capacitor C2. The control terminal of switching transistor Q1 is connected to the first end of resistor R7, the first end of capacitor C3, and the drive module 30. The second end of switching transistor Q1 is connected to the second end of resistor R7, the second end of capacitor C3, the drive module 30, and the current limiting module 60.
[0044] In some embodiments, the second flyback module 50 includes a transformer winding T1-2, a switching transistor Q2, resistors R4 and R8, capacitors C4 and C5, and a diode D4. The first end of the transformer winding T1-2 is connected to the first end of resistor R4, the first end of capacitor C4, the current limiting module 60, and the voltage divider module 10. The second end of the transformer winding T1-2 is connected to the first end of switching transistor Q2 and the positive terminal of diode D4. The negative terminal of diode D4 is connected to the second end of resistor R4 and the second end of capacitor C4. The control terminal of switching transistor Q2 is connected to the first end of resistor R8, the first end of capacitor C5, and the drive module 30. The second end of switching transistor Q2 is connected to the second end of resistor R8, the second end of capacitor C5, the drive module 30, and the current limiting module 60.
[0045] In this embodiment, taking NMOS transistor Q1 as an example, the gate of the NMOS transistor is the control terminal of Q1, the drain of the NMOS transistor is the first terminal of Q1, and the source of the NMOS transistor is the second terminal of Q1. Similarly, taking NMOS transistor Q2 as an example, the gate of the NMOS transistor is the control terminal of Q2, the drain of the NMOS transistor is the first terminal of Q2, and the source of the NMOS transistor is the second terminal of Q2.
[0046] In addition, switching transistors Q1 and Q2 can be any controllable switch, such as insulated gate bipolar transistor (IGBT) devices, integrated gate commutated thyristor (IGCT) devices, gate turn-off thyristor (GTO) devices, silicon controlled rectifier (SCR) devices, junction gate field-effect transistor (JFET) devices, MOS controlled thyristor (MCT) devices, etc.
[0047] In some embodiments, the current limiting module 60 includes a current transformer CT1, resistors Rcs1, Rcs2, R6, diodes D1 and D2. The first and second input terminals of the current transformer CT1 are connected in series with the second flyback module 50. The second output terminal of the current transformer CT1 is connected to the drive module 30. The first output terminal of the current transformer CT1 is connected to the anode of diode D1 and the cathode of diode D2. The cathode of diode D1 is connected to the first terminal of resistor Rcs2 and the control module 20. The second terminal of resistor Rcs2 is connected to the first terminal of resistor Rcs1 and the first flyback module 40. The second terminal of resistor Rcs1 is connected to the first terminal of resistor R6, the voltage divider module 10, and the second flyback module 50. The second terminal of resistor R6 is connected to the anode of diode D2.
[0048] The following combination Figure 2The working principles of the voltage divider module 10, control module 20, drive module 30, first flyback module 40, second flyback module 50, and current limiting module 60 are briefly explained.
[0049] In practical applications, when the input power supply (let its voltage be Vin) is powered on, its positive terminal BUS+ and negative terminal BUS- have voltage, and capacitors CE1 and CE2 divide the voltage. The parameters of capacitors CE1 and CE2 can be adjusted so that the voltage division between the two capacitors is Vin / 2. Then, the control module 20 supplies power to the controller U1 through resistors R1 and R2 and capacitor C1, and the controller U1 begins to operate.
[0050] When controller U1 starts working, the control signal Driver from controller U1 is sent to drivers U2 and U3 in drive module 30. Driver U2 outputs signals G1 and S1, and driver U3 outputs signals G2 and S2. The drive signals include signals G1, S1, G2, and S2. When the drive signals are sent to switches Q1 and Q2, switches Q1 and Q2 are simultaneously turned on.
[0051] In this circuit, the number of turns of transformer winding T1-1 and transformer winding T1-2 can be set to be the same. At this time, the winding current increases with the operating time, and the current in the current-limiting resistor Rcs1 and the current transformer CT1 also increases accordingly. The input and output terminals of the current transformer CT1 reduce the current value through a preset ratio (e.g., 1:100), and the current forms a loop through diode D1 and resistor Rcs2, meaning the current in resistor Rcs2 also increases (and the voltage increases as well). When an overcurrent occurs, the voltage across resistors Rcs1 and Rcs2 (i.e., the voltage to be measured) will exceed the preset voltage threshold of controller U1. At this time, controller U1 will stop outputting control signals, thereby stopping the drive module 30 from working. The first flyback module 40, the second flyback module 50, and the current-limiting module 60 will also stop working, and the voltage to be measured will drop to zero. At this time, the leakage inductance of transformer winding T1-1 and the output capacitance of switching transistor Q1 form an oscillation, and the leakage inductance of transformer winding T1-2 and the output capacitance of switching transistor Q2 form an oscillation. The oscillation can be absorbed by two absorption circuits (an absorption circuit composed of resistor R3, capacitor C2 and diode D3, and an absorption circuit composed of resistor R4, capacitor C4 and diode D4).
[0052] It is important to note that, such as Figure 2As shown, in the initial circuit design, the voltage across resistors Rcs1 and Rcs2 can be adjusted to make them equal. This ensures that the first flyback module 40 and the second flyback module 50 obtain equal energy from the bus voltage, preventing bus voltage imbalance. When external factors cause bus voltage imbalance, such as the voltage across capacitor CE1 being higher than that across capacitor CE2, in the first flyback module 40, according to U = L * di / dt (the voltage-current relationship formula for inductors), di will be higher, meaning the voltage across resistor Rcs1 will be higher than that across resistor Rcs2. Furthermore, according to Q = L * I * I * 1 / 2 (the inductor energy formula) and Q = C * U * U * 1 / 2 (the capacitor energy formula), the first flyback module 40 transfers more energy, while the second flyback module 50 transfers less. This causes the voltage across capacitor CE1 to decrease, ultimately achieving dynamic equilibrium between the voltages of capacitors CE1 and CE2. Therefore, at the initial design stage, the voltage across resistor Rcs1 can be made equal to the voltage across resistor Rcs2 by adjusting the resistance values of resistor Rcs1 and resistor Rcs2.
[0053] Please see Figure 3 , Figure 3 This is a schematic diagram of the circuit structure of the output module 70 and the feedback module 80 provided in the embodiments of this application.
[0054] In some embodiments, the output module 70 includes a transformer winding T1-3, a diode D5, a capacitor CE3, and a resistor R11. The first terminal of the transformer winding T1-3 is connected to the anode of the diode D5. The cathode of the diode D5 is connected to the anode of the capacitor CE3, the first terminal of the resistor R11, and the feedback module 80. The second terminal of the transformer winding T1-3, the cathode of the capacitor CE3, and the second terminal of the resistor R11 are all grounded. The cathode of the diode D5 is the output point of the output voltage.
[0055] In some embodiments, the feedback module 80 includes an optocoupler U4, a Zener diode ZD1, resistors R5, R10, R12, R13, R14, R15, capacitor C6, and capacitor C7. In this circuit, the first terminals of resistors R5 and R13 are both connected to the output module 70. The second terminal of resistor R5 is connected to the first terminal of resistor R15, the second terminal of capacitor C6, the second terminal of capacitor C7, and the reference input terminal of Zener diode ZD1. The second terminal of resistor R13 is connected to the first terminal of resistor R14 and the first input terminal of optocoupler U4. The second terminal of resistor R14 is connected to the first terminal of capacitor C6, the first terminal of resistor R12, the second input terminal of optocoupler U4, and the negative terminal of Zener diode ZD1. The second terminal of resistor R12 is connected to the first terminal of capacitor C7. The positive terminal of Zener diode ZD1 and the second terminal of resistor R15 are both grounded. The first output terminal of optocoupler U4 is connected to voltage divider module 10 through resistor R10, and the second output terminal of optocoupler U4 is connected to control module 20.
[0056] like Figure 3 As shown, in practical applications, transformer winding T1-3 and Figure 2 The transformer winding T1-1 is coupled to the transformer winding T1-3. The transformer winding T1-3 supplies power to the capacitor CE3 and the load (not shown) through the diode D5.
[0057] The on-state voltage (e.g., 2.5V) of the Zener diode ZD1 in the feedback module 80 is equal to the voltage of resistor R15. The output voltage (i.e., the voltage at Vout) is obtained by the voltage division of resistors R5 and R15, and is fed back to the control module 20 through optocoupler U4, causing the control module 20 to adjust the duty cycle or frequency of the control signal.
[0058] This application provides a flyback circuit 100. The flyback circuit 100 includes a voltage divider module 10, a control module 20, a drive module 30, a first flyback module 40, a second flyback module 50, a current limiting module 60, an output module 70, and a feedback module 80. The input power supply is divided by the voltage divider module 10 to power the two flyback modules (i.e., the first flyback module 40 and the second flyback module 50), reducing the voltage across each flyback module to half the input voltage (e.g., a 1500V input voltage is divided into 750V), thereby reducing the voltage withstand requirement of the switching transistor. The current limiting module 60 is connected in series with the two flyback modules to form a current detection path. When the drive module 30 outputs a drive signal, the two flyback modules operate synchronously, and the voltage to be measured is generated by the current limiting module 60. The control module 20 monitors the voltage to be measured in real time. If it exceeds a preset voltage threshold (e.g., due to leakage inductance or voltage fluctuations causing overcurrent), it immediately stops outputting the control signal, cutting off the drive to prevent damage to the switching transistor due to overvoltage / overcurrent. Feedback module 80 divides the output voltage and feeds it back to control module 20. Control module 20 adjusts the duty cycle or frequency of the drive signal to balance the energy distribution of the dual flyback module and ensure the bus midpoint voltage (i.e., Figure 1 , Figure 2 The voltage at point M is stabilized, and the operating state of the switching transistor is optimized, further reducing the withstand voltage requirement. This embodiment of the application uses a dual flyback power supply series current limiting detection, which can reduce the withstand voltage of the switching transistor in the circuit, thereby broadening the selection range of switching transistors.
[0059] This application also provides an electronic device, which includes the flyback circuit 100 described above.
[0060] The specific structure and working principle of the flyback circuit 100 can be referred to the above embodiments, and will not be repeated here.
[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of this utility model as described above. For the sake of brevity, they are not provided in detail; although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.
Claims
1. A flyback circuit, characterized by The flyback circuit comprises a voltage division module, a control module, a driving module, a first flyback module, a second flyback module, a current limiting module, an output module and a feedback module; The voltage division module is configured to be connected with an input power supply, and is connected with the first flyback module and the second flyback module; the control module is connected with the voltage division module, the driving module, the current limiting module, the feedback module and the input power supply respectively; the driving module is connected with the first flyback module, the second flyback module and the current limiting module respectively; the current limiting module is connected with the first flyback module and the second flyback module in series; the output module is coupled with the first flyback module and the second flyback module respectively, and is further connected with the feedback module; The voltage division module is configured to divide the input voltage of the input power supply to supply power to the first flyback module, the second flyback module, the control module and the feedback module; The control module is configured to obtain working current from the input power supply to start working when the input power supply is powered on, and send a control signal to the driving module when starting working; The driving module is configured to work when receiving the control signal, and output a driving signal to make the first flyback module, the second flyback module and the current limiting module work based on the driving signal; The current limiting module is configured to generate a to-be-tested voltage when working; the control module is further configured to stop outputting the control signal when detecting that the to-be-tested voltage is greater than a preset voltage threshold; wherein the voltage value of the to-be-tested voltage rises with the working time; The output module is configured to obtain electric energy from the first flyback module and the second flyback module, and generate an output voltage; The feedback module is configured to divide the output voltage to obtain a feedback voltage; the control module is further configured to adjust the duty cycle or frequency of the control signal based on the feedback voltage, and further adjust the duty cycle or frequency of the driving signal output by the driving module.
2. The flyback circuit of claim 1, wherein, The control module comprises a controller U1, a resistor R1, a resistor R2 and a capacitor C1; A first end of the resistor R1 is connected with the input power supply; a second end of the resistor R1 is connected with a first end of the resistor R2; a second end of the resistor R2 is connected with a power supply end of the controller U1 and a first end of the capacitor C1; a second end of the capacitor C1 is connected with the voltage division module and a ground end of the controller U1 respectively; a voltage reference end of the controller U1 is connected with the feedback module; a signal output end of the controller U1 is connected with the driving module; and a current reference end of the controller U1 is connected with the current limiting module.
3. The flyback circuit of claim 1, wherein, The current limiting module comprises a current transformer CT1, a resistor Rcs1, a resistor Rcs2, a resistor R6, a diode D1 and a diode D2; The first input end and the second input end of the current transformer CT1 are connected in series with the second flyback module, the second output end of the current transformer CT1 is connected with the driving module, the first output end of the current transformer CT1 is connected with the positive electrode of the diode D1 and the negative electrode of the diode D2, the negative electrode of the diode D1 is connected with the first end of the resistor Rcs2 and the control module respectively, the second end of the resistor Rcs2 is connected with the first end of the resistor Rcs1 and the first flyback module respectively, the second end of the resistor Rcs1 is connected with the first end of the resistor R6, the voltage division module and the second flyback module respectively, and the second end of the resistor R6 is connected with the positive electrode of the diode D2.
4. The flyback circuit of claim 1, wherein, The feedback module comprises an optical coupler U4, a voltage stabilizing tube ZD1, resistors R5, R10, R12, R13, R14, R15, capacitors C6 and C7. The first end of the resistor R5 and the first end of the resistor R13 are connected with the output module, the second end of the resistor R5 is connected with the first end of the resistor R15, the second end of the capacitor C6, the second end of the capacitor C7 and the reference input end of the voltage stabilizing tube ZD1 respectively, the second end of the resistor R13 is connected with the first end of the resistor R14 and the first input end of the optical coupler U4 respectively, the second end of the resistor R14 is connected with the first end of the capacitor C6, the first end of the resistor R12, the second input end of the optical coupler U4 and the negative electrode of the voltage stabilizing tube ZD1 respectively, the second end of the resistor R12 is connected with the first end of the capacitor C7, the positive electrode of the voltage stabilizing tube ZD1 and the second end of the resistor R15 are grounded, the first output end of the optical coupler U4 is connected with the voltage division module through the resistor R10, and the second output end of the optical coupler U4 is connected with the control module.
5. The flyback circuit of claim 1, wherein, The driving module comprises a driver U2 and a driver U3. The signal input end of the driver U2 and the signal input end of the driver U3 are connected with the control module, the ground end of the driver U2 and the ground end of the driver U3 are connected with the voltage division module, the gate control end of the driver U2 is connected with the first flyback module, the source connection end of the driver U2 is connected with the first flyback module and the current limiting module respectively, the gate control end of the driver U3 is connected with the second flyback module, and the source connection end of the driver U3 is connected with the second flyback module.
6. The flyback circuit of claim 1, wherein, The first flyback module comprises a transformer winding T1-1, a switch tube Q1, resistors R3 and R7, capacitors C2 and C3, and a diode D3. The first end of the transformer winding T1-1 is connected with the first end of the resistor R3, the first end of the capacitor C2, the input power supply and the voltage division module respectively, the second end of the transformer winding T1-1 is connected with the first end of the switch tube Q1 and the anode of the diode D3 respectively, the cathode of the diode D3 is connected with the second end of the resistor R3 and the second end of the capacitor C2 respectively, the control end of the switch tube Q1 is connected with the first end of the resistor R7, the first end of the capacitor C3 and the driving module respectively, the second end of the switch tube Q1 is connected with the second end of the resistor R7, the second end of the capacitor C3, the driving module and the current limiting module respectively.
7. The flyback circuit of claim 1, wherein, The second flyback module comprises a transformer winding T1-2, a switch tube Q2, a resistor R4, a resistor R8, a capacitor C4, a capacitor C5 and a diode D4. The first end of the transformer winding T1-2 is connected with the first end of the resistor R4, the first end of the capacitor C4, the current limiting module and the voltage division module respectively, the second end of the transformer winding T1-2 is connected with the first end of the switch tube Q2 and the anode of the diode D4 respectively, the cathode of the diode D4 is connected with the second end of the resistor R4 and the second end of the capacitor C4 respectively, the control end of the switch tube Q2 is connected with the first end of the resistor R8, the first end of the capacitor C5 and the driving module respectively, the second end of the switch tube Q2 is connected with the second end of the resistor R8, the second end of the capacitor C5, the driving module and the current limiting module respectively.
8. The flyback circuit of claim 1, wherein, The voltage division module comprises a capacitor CE1 and a capacitor CE2. The anode of the capacitor CE1 is connected with the control module, the first flyback module and the positive pole of the input power supply respectively, the cathode of the capacitor CE1 is connected with the anode of the capacitor CE2, the current limiting module, the second flyback module, the control module, the driving module and the feedback module respectively, the cathode of the capacitor CE2 is connected with the current limiting module and the negative pole of the input power supply respectively.
9. The flyback circuit according to any one of claims 1 to 8, characterized in that, The output module comprises a transformer winding T1-3, a diode D5, a capacitor CE3 and a resistor R11. The first end of the transformer winding T1-3 is connected with the anode of the diode D5, the cathode of the diode D5 is connected with the anode of the capacitor CE3, the first end of the resistor R11 and the feedback module respectively, the second end of the transformer winding T1-3, the cathode of the capacitor CE3 and the second end of the resistor R11 are all grounded; wherein the cathode of the diode D5 is the output point of the output voltage.
10. An electronic device, comprising: The electronic device comprises the flyback circuit according to any one of claims 1 to 9.