Flyback self-driven synchronous rectification circuit and synchronous rectifier
By replacing diodes with MOSFETs in the rectifier circuit and utilizing the secondary auxiliary winding for self-drive, the driving circuit is optimized, solving the problem of high rectifier circuit losses and achieving efficient rectification. This method is suitable for small-size, high-power-density DC/DC modules.
Patent Information
- Application Number
- CN202422775697.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-11-14
AI Technical Summary
Existing rectifier circuits suffer from significant losses, especially under low voltage and high current conditions, resulting in low rectifier circuit efficiency.
A flyback self-driven synchronous rectifier circuit is adopted, which uses MOSFETs to replace traditional diodes for rectification and self-drives the MOSFETs through the secondary auxiliary winding. The driving circuit is optimized by combining components such as capacitors and resistors, thus simplifying the circuit structure.
It reduces the losses of the rectifier circuit and improves the efficiency of the rectifier circuit. It is suitable for small-size, high-power-density DC/DC modules, simplifies circuit design, and increases layout space.
Smart Images
Figure CN223527982U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to rectifier circuit's technical field especially relates to a kind of flyback self-drive synchronous rectifier circuit and synchronous rectifier. BACKGROUND
[0002] Rectifier circuit is the circuit of AC power conversion DC power.The rectifier circuit in prior art is mostly adopted rectifier diode,as the loss of diode is larger,especially in the case of low voltage large current loss is more prominent,thus leading to the loss of entire rectifier circuit is larger. SUMMARY
[0003] In view of the deficiencies in the prior art, the utility model provides a kind of flyback self-drive synchronous rectifier circuit and synchronous rectifier, solve the problem of the loss of rectifier circuit in prior art is larger.
[0004] At least one embodiment of the utility model provides a kind of flyback self-drive synchronous rectifier circuit, including: input unit, first switch unit, transformer T1, MOS tube Q2 and output unit, wherein, the transformer T1 includes primary winding, secondary main winding and secondary auxiliary winding;
[0005] The input unit is connected with one end of the primary winding, and the other end of the primary winding is connected to a common terminal through the two ends of the first switch unit, and the control end of the first switch unit is connected with a control signal to control the on-off of the two ends of the first switch unit;
[0006] The secondary main winding is connected with the output unit in sequence through the source and drain of the MOS tube Q2;
[0007] The secondary auxiliary winding is connected with the gate of the MOS tube Q2, to control the conduction of the MOS tube Q2 when the secondary auxiliary winding receives the energy transmitted by the primary winding.
[0008] The technical scheme disclosed by the utility model has at least the following beneficial effects:
[0009] Through the above setting, when the input unit is in the power-on state, at this time, when the control end of the first switch unit accepts the control signal to be in the conduction state, the primary winding of transformer T1 accepts and stores the energy from the input unit;
[0010] At this time, the MOS tube Q2 is in the off state, when the control end of the first switch unit accepts the control signal, the primary winding of the transformer T1 transmits the stored energy to the secondary main winding and the secondary auxiliary winding, at this time, the secondary auxiliary winding controls the MOS tube Q2 to be turned on, and the secondary main winding transmits the voltage to the output unit through the MOS tube Q2, thereby completing synchronous rectification. The rectification mode of the secondary main winding of the utility model is changed from the traditional diode rectification to the MOS tube rectification, because the on-resistance of the MOS tube is much smaller than that of the conventional rectification diode, so that the loss of the whole circuit is smaller, and the efficiency of the product can be greatly improved. In addition, the MOS tube Q2 adopts the self-driven mode of the secondary auxiliary winding, which can simplify the circuit and improve the layout space. It has broad application prospects in the field of small size, high power density DC / DC module of the equipment power supply system.
[0011] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the primary winding comprises a port X1 and a port X2, the secondary main winding comprises a port Y1 and a port Y2, and the output unit comprises a first output end VO and a second output end GND, wherein the port X1 and the port Y2 are the same name end, and the port X2 and the port Y1 are the same name end.
[0012] The input unit is connected with the port X1, and the first switch unit is connected with the port X2.
[0013] The port Y1 is connected with the first output end VO in sequence through the source and the drain of the MOS tube Q2.
[0014] The port Y2 is connected with the second output end GND.
[0015] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the output unit further comprises a capacitor C4 and a capacitor C5, wherein,
[0016] The first output end VO is connected with the second output end GND through the capacitor C4 and the capacitor C5 respectively.
[0017] The technical scheme provided by the utility model has at least the following beneficial effects:
[0018] Through the capacitor C4 and the capacitor C5, the output unit can provide the effects of filtering and energy storage.
[0019] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the input unit comprises a first input end Vin, a second input end Gin and a capacitor C1, wherein,
[0020] The first input terminal Vin is connected with the port X1, and the first input terminal Vin is also connected with the second input terminal Gin through the capacitor C1.
[0021] The second input terminal Gin is connected with a common terminal.
[0022] The technical scheme provided by the utility model has at least the following beneficial effects:
[0023] Through the capacitor C1, the voltage signal output by the input unit can be filtered and energy can be stored.
[0024] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the auxiliary winding of the secondary side comprises a port Y3 and a port Y4, wherein the port Y3 and the port X2 are homonymous terminals, and the port Y4 and the port X1 are homonymous terminals.
[0025] The port Y3 and the port Y4 are connected with the gate of the MOS tube Q2.
[0026] The technical scheme provided by the utility model has at least the following beneficial effects:
[0027] At this time, when the first switch unit is turned on, the port X2 is at low level, and its homonymous terminal port Y3 is also at low level, so the GS voltage of the MOS tube Q2 is at negative level, and the MOS tube Q2 cannot be turned on.
[0028] When the first switch unit is turned off, the port X2 is at high level, and its homonymous terminal port Y3 is also at high level, and at the same time, the auxiliary winding of the secondary side obtains a driving voltage higher than the MOS tube Q2 according to the turn ratio with the main winding of the secondary side, so that the MOS tube Q2 is turned on, and the function of synchronous rectification is realized.
[0029] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the circuit further comprises a resistor R1 and a capacitor C6, and the port Y3 is connected with the gate of the MOS tube Q2 through the resistor R1 and the capacitor C6 connected in series.
[0030] The technical scheme provided by the utility model has at least the following beneficial effects:
[0031] Through the above setting, the resistor R1 can be used for adjusting the slope of the rising of the driving voltage, and at the same time, the driving oscillation caused by the inductance of the driving loop is eliminated, and the capacitor C6 can control the size of the driving voltage.
[0032] In the flyback self-driven synchronous rectification circuit provided in one of the embodiments of the utility model, the circuit further comprises a resistor R2, and the port Y4 is connected with the gate of the MOS tube Q2 through the resistor R2.
[0033] The technical scheme provided by the utility model has at least the following beneficial effects:
[0034] Through the above setting, the resistor R2 can be used as a discharge resistor to avoid the influence of external static electricity on the MOS tube Q2.
[0035] In the flyback self-driven synchronous rectification circuit provided by one of the embodiments of the utility model, the circuit further comprises a clamping diode D1 and a clamping diode D2, and the port Y4 is connected with the gate of the MOS tube Q2 in sequence through the anode of the clamping diode D1, the cathode of the clamping diode D1, the cathode of the clamping diode D2 and the anode of the clamping diode D2.
[0036] The technical scheme provided by the utility model has at least the following beneficial effects:
[0037] Through the setting of the clamping diode D1 and the clamping diode D2, the voltage peak of the gate of the MOS tube Q2 can be reduced to protect the MOS tube Q2.
[0038] In the flyback self-driven synchronous rectification circuit provided by one of the embodiments of the utility model, the circuit further comprises a resistor R3 and a capacitor C3, and the source of the MOS tube Q2 is connected with the drain of the MOS tube Q2 through the connected resistor R3 and capacitor C3 in series.
[0039] The technical scheme provided by the utility model has at least the following beneficial effects:
[0040] The resistor R3 and the capacitor C3 can form a resistance-capacitance absorption to reduce the stress between the source and the drain of the MOS tube Q2 and prevent the voltage breakdown of the MOS tube Q2 to protect the MOS tube Q2.
[0041] The utility model further provides a synchronous rectifier which comprises a rectifier body and a flyback self-driven synchronous rectification circuit as described above arranged in the body. BRIEF DESCRIPTION OF DRAWINGS
[0042] Figure 1 The utility model relates to a circuit principle diagram of a flyback self-driven synchronous rectification circuit.
[0043] In the drawings, the components represented by the reference numerals are listed as follows:
[0044] S1, input unit, S2, first switch unit, S3, output unit. DETAILED DESCRIPTION
[0045] The principles and features of the utility model will be described below in combination with the drawings, and the examples are only used to explain the utility model and not to limit the scope of the utility model.
[0046] The utility model provides a kind of flyback self-driving synchronous rectification circuit, please refer to Figure 1 As shown in the figure, comprising: input unit S1, first switch unit S2, transformer T1, MOS tube Q2 and output unit S3, wherein, the transformer T1 includes primary winding, secondary main winding and secondary auxiliary winding, need to understand, in transformer T1 as shown in Figure 1 The primary winding is the winding located on the left side of the transformer T1, the secondary main winding is the winding located on the right upper side of the transformer T1, and the secondary auxiliary winding is the winding located on the right lower side of the transformer T1.
[0047] One end of the primary winding is connected to the input unit S1, and the other end of the primary winding is connected to the common terminal through the two ends of the first switch unit S2. The control end of the first switch unit S2 is connected with a control signal to control the on-off of the two ends of the first switch unit S2.
[0048] In this embodiment, the first switch unit S2 is a MOS tube Q1. The gate of the MOS tube Q1 is connected to a control chip. The duty cycle of the PWM signal sent by the control chip can be used to realize the off and on of the MOS tube Q1.
[0049] The other end of the primary winding is connected to the common terminal through the drain and source of the MOS tube Q1.
[0050] The secondary main winding is connected to the output unit S3 through the source and drain of the MOS tube Q2 in sequence.
[0051] The secondary auxiliary winding is connected to the gate of the MOS tube Q2 to control the conduction of the MOS tube Q2 when the secondary auxiliary winding receives the energy transmitted by the primary winding.
[0052] The transformer T1 used in the circuit does not use the tapping method, but uses a separate device to build a driving circuit, and does not use the driving chip driving method. When the input range is wide, the parameters of the driving circuit can be reasonably configured, so that the efficiency is close when the high-end-nominal-low-end input. At the same time, it solves the problem of sharp peak of driving voltage of secondary MOS tube Q2 when primary MOS tube Q1 is off and on, so that the maximum voltage of the sharp peak is also within a reasonable range, and the secondary MOS tube Q2 will not be damaged.
[0053] Through the above setting, when the input unit S1 is in the energized state, at this time, the control end of the first switch unit S2 is in the conductive state when receiving the control signal, and the primary winding of the transformer T1 receives and stores the energy from the input unit S1.
[0054] At this time, the MOS tube Q2 is in the off state, when the control end of the first switch unit S2 accepts the control signal to be in the off state, the primary winding of the transformer T1 transmits the stored energy to the secondary main winding and the secondary auxiliary winding, at this time, the secondary auxiliary winding controls the MOS tube Q2 to be turned on, and the secondary main winding transmits the voltage to the output unit S3 through the MOS tube Q2, thereby completing synchronous rectification. The rectification mode of the secondary main winding of the utility model is changed from the traditional diode rectification to the MOS tube rectification, because the on-resistance of the MOS tube is much smaller than that of the conventional rectification diode, so that the loss of the whole circuit is smaller, and the efficiency of the product can be greatly improved. In addition, the MOS tube Q2 adopts the mode of self-driving of the secondary auxiliary winding, which can simplify the circuit and improve the layout space. It has broad application prospects in the field of small size, high power density DC / DC module of equipment power supply system.
[0055] Specifically, the primary winding includes port X1 and port X2, the secondary main winding includes port Y1 and port Y2, and the output unit S3 includes first output end VO and second output end GND, wherein the port X1 and the port Y2 are the same name end, and the port X2 and the port Y1 are the same name end.
[0056] The input unit S1 is connected with the port X1, and the first switch unit S2 is connected with the port X2.
[0057] The port Y1 is connected with the first output end VO through the source and the drain of the MOS tube Q2 in sequence.
[0058] The port Y2 is connected with the second output end GND.
[0059] Specifically, the output unit S3 further includes capacitor C4 and capacitor C5, wherein,
[0060] The first output end VO is connected with the second output end GND through the capacitor C4 and the capacitor C5 respectively.
[0061] Through the capacitor C4 and the capacitor C5, the output unit S3 can provide the effect of filtering and energy storage.
[0062] Specifically, the input unit S1 includes first input end Vin, second input end Gin and capacitor C1, wherein,
[0063] The first input end Vin is connected with the port X1, and the first input end Vin is further connected with the second input end Gin through the capacitor C1.
[0064] The second input end Gin is connected with the common end.
[0065] The voltage signal outputted by the input unit S1 can be filtered and energy can be stored through the capacitor C1.
[0066] Specifically, the auxiliary winding of the secondary side comprises a port Y3 and a port Y4, wherein the port Y3 is a homonymous port with the port X2, and the port Y4 is a homonymous port with the port X1.
[0067] The port Y3 and the port Y4 are connected to the gate of the MOS tube Q2.
[0068] At this time, when the first switch unit S2 is turned on, the port X2 is at low level, and its homonymous port Y3 is also at low level, so the GS voltage of the MOS tube Q2 is at negative level, and the MOS tube Q2 cannot be turned on.
[0069] When the first switch unit S2 is turned off, the port X2 is at high level, and its homonymous port Y3 is also at high level, and the auxiliary winding of the secondary side obtains a driving voltage higher than that of the MOS tube Q2 according to the turn ratio with the main winding of the secondary side, so that the MOS tube Q2 is turned on to realize the function of synchronous rectification.
[0070] Specifically, the circuit further comprises a resistor R1 and a capacitor C6, and the port Y3 is connected to the gate of the MOS tube Q2 through the resistor R1 and the capacitor C6 connected in series.
[0071] Through the above setting, the resistor R1 can be used to adjust the slope of the rising of the driving voltage, and at the same time, eliminate the driving oscillation caused by the inductance of the driving circuit, and the capacitor C6 can control the size of the driving voltage.
[0072] Specifically, the circuit further comprises a resistor R2, and the port Y4 is connected to the gate of the MOS tube Q2 through the resistor R2.
[0073] Through the above setting, the resistor R2 can be used as a discharge resistor to avoid the influence of external static electricity on the MOS tube Q2.
[0074] Specifically, the circuit further comprises a clamping diode D1 and a clamping diode D2, and the port Y4 is connected to the gate of the MOS tube Q2 through the anode of the clamping diode D1, the cathode of the clamping diode D1, the cathode of the clamping diode D2 and the anode of the clamping diode D2 in sequence.
[0075] Through the setting of the clamping diode D1 and the clamping diode D2, the voltage spike of the gate of the MOS tube Q2 can be reduced to protect the MOS tube Q2.
[0076] Specifically, the circuit further comprises a resistor R3 and a capacitor C3, and the source of the MOS tube Q2 is connected to the drain of the MOS tube Q2 through the resistor R3 and the capacitor C3 connected in series.
[0077] The resistor R3 and the capacitor C3 can constitute a resistance-capacitance absorption, reduce the stress between the source and the drain of the MOS tube Q2, prevent the voltage breakdown of the MOS tube Q2, and protect the MOS tube Q2.
[0078] Through the above setting, in the embodiment, the input voltage range of the input unit S1 is between 15V and 50V, the output voltage of the output unit S3 is 5V, the output power can be increased from 20W to 40W, the effect is up to 87% or more, the circuit structure is simple, the layout space can be improved, the efficiency is larger, and the circuit has a wide application prospect.
[0079] In summary, through the above circuit:
[0080] When the input unit S1 is in the power-on state, at this time, the gate end of the MOS tube Q1 receives a control signal to be in the on state, the primary winding of the transformer T1 receives and stores the energy from the input unit S1, the port X2 is low, and the same end port Y3 is also low, so that the GS voltage of the MOS tube Q2 is negative, and the MOS tube Q2 cannot be turned on.
[0081] When the gate end of the MOS tube Q1 receives a control signal to be in the off state, the primary winding of the transformer T1 transmits the stored energy to the secondary main winding and the secondary auxiliary winding, the port X2 is high, the same end port Y3 is also high, and the secondary auxiliary winding obtains a driving voltage higher than the MOS tube Q2 according to the turn ratio with the secondary main winding, so that the MOS tube Q2 is turned on, and the secondary main winding transmits the voltage to the output unit S3 through the MOS tube Q2, and then completes synchronous rectification.
[0082] The rectification mode of the secondary main winding of the utility model is changed from the traditional diode rectification to the MOS tube rectification, because the on resistance of the MOS tube is much smaller than that of the conventional rectification diode, the loss of the whole circuit is smaller, the efficiency of the product can be greatly improved, and in addition, the MOS tube Q2 adopts the self-driven mode of the secondary auxiliary winding, so that the circuit can be simplified and the layout space can be improved. The utility model has a wide application prospect in the occasion of small size and high power density DC / DC module in the equipment power supply system.
[0083] The transformer T1 used in the circuit does not adopt the tapping mode, but adopts the driving circuit built by separate devices, and does not adopt the driving mode of the driving chip, when the input range is wide, the parameters of the driving circuit can be reasonably configured, so that the efficiency is close when the high end-nominal-low end input. At the same time, the problem of sharp peak of the driving voltage of the secondary MOS tube Q2 caused by the on-off of the primary MOS tube Q1 is solved, so that the maximum voltage of the sharp peak is also in a reasonable range, and the secondary MOS tube Q2 will not be damaged.
[0084] The utility model further provides a synchronous rectifier, including rectifier body and the configuration in the body like above-mentioned one kind of flyback self -driving synchronous rectification circuit.
[0085] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Thus, features defined with "first", "second" or "third" can explicitly or implicitly include at least one of the features. In the description of the utility model, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.
[0086] In the utility model, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise specifically limited. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.
[0087] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of different embodiments or examples without contradiction.
[0088] Although the embodiments of the utility model have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary, and cannot be understood as limiting the utility model, and the skilled in the art can change, modify, replace and modify the above-mentioned embodiments within the scope of the utility model.
Claims
1. A flyback self-driven synchronous rectification circuit, characterized in that, The circuit comprises an input unit (S1), a first switch unit (S2), a transformer T1, a MOS tube Q2 and an output unit (S3), wherein the transformer T1 comprises a primary winding, a main secondary winding and an auxiliary secondary winding. The input unit (S1) is connected to one end of the primary winding, the other end of the primary winding is connected to a common terminal through the two ends of the first switch unit (S2), and the control end of the first switch unit (S2) is connected with a control signal to control the on-off of the two ends of the first switch unit (S2). The main secondary winding is connected to the output unit (S3) through the source and drain of the MOS tube Q2 in sequence. The auxiliary secondary winding is connected to the gate of the MOS tube Q2, so as to control the conduction of the MOS tube Q2 when the auxiliary secondary winding receives the energy transmitted by the primary winding. The primary winding comprises a port X1 and a port X2, the main secondary winding comprises a port Y1 and a port Y2, and the output unit (S3) comprises a first output terminal VO and a second output terminal GND, wherein the port X1 and the port Y2 are the same name terminals, and the port X2 and the port Y1 are the same name terminals.
2. The flyback self-driven synchronous rectification circuit according to claim 1, characterized in that, The input unit (S1) is connected to the port X1, and the first switch unit (S2) is connected to the port X2. The port Y1 is connected to the first output terminal VO through the source and drain of the MOS tube Q2 in sequence. The port Y2 is connected to the second output terminal GND. The output unit (S3) further comprises a capacitor C4 and a capacitor C5, wherein the first output terminal VO is connected to the second output terminal GND through the capacitor C4 and the capacitor C5 respectively.
3. The flyback self-driven synchronous rectification circuit according to claim 2, characterized in that, The input unit (S1) comprises a first input terminal Vin, a second input terminal Gin and a capacitor C1, wherein the first input terminal Vin is connected to the port X1, and the first input terminal Vin is further connected to the second input terminal Gin through the capacitor C1. The second input terminal Gin is connected to a common terminal.
4. The flyback self-driven synchronous rectification circuit according to claim 2, characterized in that, The auxiliary secondary winding comprises a port Y3 and a port Y4, wherein the port Y3 and the port X2 are the same name terminals, and the port Y4 and the port X1 are the same name terminals. The port Y3 and the port Y4 are both connected to the gate of the MOS tube Q2. The circuit further comprises a resistor R1 and a capacitor C6, and the port Y3 is connected to the gate of the MOS tube Q2 through the resistor R1 and the capacitor C6 connected in series.
5. A flyback self-driven synchronous rectification circuit according to any one of claims 2 to 4, wherein, The circuit further comprises a resistor R2, and the port Y4 is connected to the gate of the MOS tube Q2 through the resistor R2. The circuit further comprises a clamping diode D1 and a clamping diode D2, and the port Y4 is connected to the gate of the MOS tube Q2 through the anode of the clamping diode D1, the cathode of the clamping diode D1, the cathode of the clamping diode D2 and the anode of the clamping diode D2 in sequence.
6. The flyback self-driven synchronous rectification circuit according to claim 5, wherein, The circuit further comprises a resistor R3 and a capacitor C3, wherein the source of the MOS tube Q2 is connected to the drain of the MOS tube Q2 through the resistor R3 and the capacitor C3 connected in series.
7. The flyback self-driven synchronous rectification circuit according to claim 5, wherein, 8. The flyback self-driven synchronous rectification circuit according to claim 5, wherein, 9. The flyback self-driven synchronous rectification circuit of claim 1, wherein, 10. A synchronous rectifier characterized by, The rectifier comprises a rectifier body and a flyback self-driven synchronous rectification circuit as claimed in any one of claims 1 to 9 arranged in the rectifier body.