Soft-switching high gain dc-dc converter based on active clamp and coupled inductor

Abstract

The utility model belongs to the field of switching power supply discloses a kind of soft switching high-gain DC-DC converter based on active clamping and coupled inductance, compared with prior art element quantity significantly reduces, main, auxiliary switch are N type MOSFET, with the characteristics of small on-resistance, switching speed is fast, adapt high-frequency soft switching scene, through active clamping technology, main, auxiliary switch are realized zero-voltage opening, greatly reduce switching loss.The converter can obtain high voltage gain under low duty cycle condition, and the gain can be further improved with the increase of coupled inductance turns ratio.Active clamping circuit not only suppresses the voltage peak of switch tube, reduces the device size, cost and on-resistance loss, but also recovers the drain energy of coupled inductance, significantly alleviates the reverse recovery problem of diode.The above scheme can balance the relationship between gain, stress and element quantity, meet the demand of photovoltaic, fuel cell and other low-voltage direct current source for high-gain, low-loss, small volume converter.

Description

Technical Field

[0001] This utility model belongs to the field of switching power supply technology, and is a soft-switching high-gain DC-DC converter based on active clamping and coupled inductor. Background Technology

[0002] In energy conversion scenarios involving low-voltage DC sources such as photovoltaics and fuel cells, high-gain DC-DC converters are core devices connecting low-voltage sources to medium- to high-voltage loads. The output voltage of a single string of photovoltaic modules is typically 20–40V, and the output voltage of a fuel cell stack is mostly 30–60V. However, in practical applications, it is often necessary to boost these voltages to 380V or even higher DC bus voltages. Therefore, "high gain" is a core performance indicator for such converters. However, existing topologies have significant problems adapting to this requirement, specifically as follows:

[0003] While traditional Boost converters have a simple structure, their voltage gain is only 1 / (1-D) (where D is the duty cycle). To achieve a gain of more than 10 times, the duty cycle needs to be close to 0.9, which presents three problems: First, the voltage stress on the switching transistor is as high as 1 / (1-D) of the input voltage (i.e., more than 10 times the input voltage), far exceeding the voltage withstand capability of conventional devices, requiring the selection of high-voltage switching transistors, which leads to increased on-resistance and higher costs. Second, the inductor current ripple increases sharply with the increase of the duty cycle, significantly increasing core losses and copper losses, and efficiency can drop below 80%. Third, when the duty cycle is close to its limit, the control precision requirements are extremely high, and even a small disturbance can lead to circuit instability and a significant decrease in reliability.

[0004] Cascaded Boost topology increases gain by connecting multiple Boost units in series. While this avoids the duty cycle limitation of a single-stage Boost, it introduces new drawbacks: First, the number of components increases proportionally with the number of cascaded stages, leading to larger circuit size and higher costs. Furthermore, parasitic parameters of cascaded nodes (such as wiring inductance and contact resistance) further reduce efficiency. Second, the voltage stress distribution of each stage is uneven, with the front-end units bearing higher voltages, making them vulnerable to failure. Additionally, multi-stage coordinated control is complex, with slow dynamic response, making it difficult to adapt to the large voltage fluctuations in photovoltaic and fuel cell output voltages.

[0005] Coupled inductor topologies can theoretically increase the gain to n / (1-D) by adjusting the turns ratio (n) of the primary and secondary windings, significantly improving the gain compared to traditional Boost converters. However, their inherent leakage inductance introduces a new technical challenge: at the moment the switch is turned off, the back electromotive force generated by the leakage inductance creates a voltage spike of hundreds to thousands of volts, far exceeding the voltage withstand limit of the switch. To suppress this spike, existing solutions require additional RC or RCD absorption circuits, but these essentially dissipate leakage inductance energy through resistors, leading to energy loss and increased circuit complexity. Furthermore, the waste of leakage inductance energy contradicts the core objective of "efficient energy utilization" in photovoltaic and fuel cell systems, and the heat generated by the absorption components increases the difficulty of heat dissipation design, further limiting power density improvements.

[0006] Currently, with the rapid development of new energy power generation and hydrogen energy applications, the market requirements for converters have upgraded from simply high gain to a comprehensive performance balance of "high gain, high efficiency, low stress, and small size." Although current solutions focus on non-isolated architectures, attempting to recover leakage inductance energy through active clamping and achieve ZVS soft switching, existing solutions still struggle to balance the relationship between gain, stress, and component count, failing to meet the high gain, low loss, and small size requirements of low-voltage DC sources such as photovoltaics and fuel cells. Utility Model Content

[0007] The purpose of this invention is to solve the problems in the prior art and provide a soft-switching high-gain DC-DC converter based on active clamping and coupled inductors.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention proposes a soft-switching high-gain DC-DC converter based on active clamping and coupled inductors, comprising a first coupled inductor CI-1 and a second coupled inductor CI-2. Both the first coupled inductor CI-1 and the second coupled inductor CI-2 have primary windings and secondary windings. The primary winding inductance includes a first inductor L. P1 Second inductor L P2 The secondary winding inductance includes the third inductor L. S1 and the fourth inductor L S2 ;

[0010] Input voltage V in The positive terminal is connected to the first inductor L of the first coupling inductor CI-1. P1 The first inductance L of the first coupling inductor CI-1 P1 The first branch at the other end is connected to the first switched capacitor C1, and the second branch is connected to the auxiliary switch S. A The source and the third branch are connected to the drain of the main switch S; the first branch at the other end of the first switching capacitor C1 is connected to the second inductor L of the second coupling inductor CI-2.P2 The second branch connects to the first diode D1; the second inductor L of the second coupling inductor CI-2 P2 The first branch at the other end and the auxiliary switch S A The drains are connected, and the second branch is connected to the clamping capacitor C. C The first branch at the other end of the first diode D1 is connected to the third inductor L of the first coupling inductor CI-1. S1 The second branch is connected to the second diode D2, and the third branch is connected to the output capacitor C. O2 The fourth branch is connected to the output capacitor C. O1 The third inductor L of the first coupling inductor CI-1 S1 The other end is connected to the fourth inductor L of the second coupling inductor CI-2. S2 The fourth inductor L of the second coupling inductor CI-2 S2 The other end is connected to the second switched capacitor C2, and the third diode D3 and the other end of the second diode D2 are connected together and then connected to the other end of the second switched capacitor C2; the other end of the third diode D3 is connected to the output capacitor C. O2 The other end is connected to the load resistor R. L Load resistance R L The other end, output capacitor C O1 The other end, clamping capacitor C C At the other end, the source of the main switch S and the input voltage V in After the negative terminal is connected to ground, the auxiliary switch S A A first buffer protection unit is connected in parallel above, and a second buffer protection unit is connected in parallel on the main switch S.

[0011] Preferably, the first buffer protection unit includes a first parasitic diode D. a and the first parasitic capacitance C a The first parasitic diode D a and the first parasitic capacitance C a Parallel connection in auxiliary switch S A superior.

[0012] Preferably, the second buffer protection unit includes a second parasitic diode D. r Second parasitic capacitance C r The second parasitic diode D r Second parasitic capacitance C r It is connected in parallel to the main switch S.

[0013] Preferably, the drain of the main switch S is connected to the auxiliary switch S A The source poles are connected.

[0014] Preferably, the auxiliary switch S A With the clamping capacitor C CThis forms an active clamping network.

[0015] Preferably, the capacitance value of the first switched capacitor C1 is equal to the capacitance value of the second switched capacitor C2.

[0016] Preferably, the first diode D1, the second diode D2, and the third diode D3 are all Schottky diodes.

[0017] Preferably, the main switch S and the auxiliary switch S A All are N-type MOSFETs.

[0018] Preferably, the number of turns on the primary side of both the first coupling inductor CI-1 and the second coupling inductor CI-2 is twice the number of turns on the secondary side.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention proposes a soft-switching high-gain DC-DC converter based on active clamping and coupled inductors, which reduces the number of components. High voltage gain is achieved at low duty cycles through active clamping and two coupled inductors. An active clamping circuit is employed to reduce switching voltage spikes and recover leakage energy from the coupled inductors. This leakage energy mitigation alleviates the reverse recovery problem of the diodes. Therefore, the voltage stress on the switches and diodes is minimal, contributing to their efficient operation at high gain. The proposed converter consists of two switches, serving as the main and auxiliary switches respectively. These switches operate in a zero-voltage switching manner, reducing conduction and switching losses to extremely low levels, thereby significantly improving efficiency. The combination of these components balances the relationship between gain, stress, and component count, meeting the requirements of low-voltage DC sources such as photovoltaics and fuel cells for high gain, low loss, and small size converters.

[0021] Furthermore, the main switch S not only handles the switching of the main power channel, but also discharges the junction capacitor using the leakage inductance current at the moment of turn-off, achieving zero-voltage turn-on; during the conduction period, it stores energy together with the coupling inductor, and after turn-off, it transfers the remaining energy to the output through the active clamping circuit, thus playing the dual role of power transmission and soft switching.

[0022] Furthermore, the clamping capacitor C C Instantly absorbs leakage inductance spike energy and smoothly transfers it to the output, reducing switching stress from hundreds of volts to below 200V; C C Simultaneously, as a resonant capacitor, it, together with the leakage inductance, determines the ZVS boundary, serving as an energy buffer for the reliable and efficient operation of the entire converter.

[0023] Furthermore, through the parasitic diode D a and parasitic capacitance C a The coordination of auxiliary switches S A When D is turned offa Provides a freewheeling path for inductive loads, preventing reverse voltage from breaking down the switch; C a The voltage change rate during buffer switch operation, combined with the active clamping network, enables zero-voltage turn-on, reduces switching losses, suppresses electromagnetic interference, and improves the stability of the converter during high-frequency operation.

[0024] Furthermore, the main switch S serves as the core of power transmission, D r Freewheeling current flows when the device is turned off to prevent back electromotive force from damaging the device; C r It absorbs the voltage spike at the moment the switch is turned off, reduces turn-off losses, further reduces switching losses, and improves overall efficiency. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a topology diagram of the soft-switching high-gain DC-DC converter of this utility model.

[0027] Figure 2 This is a schematic diagram of the operating mode 1 of the soft-switching high-gain DC-DC converter of this utility model.

[0028] Figure 3 This is a schematic diagram of the operating mode 2 of the soft-switching high-gain DC-DC converter of this utility model.

[0029] Figure 4 This is a schematic diagram of the operating mode 3 of the soft-switching high-gain DC-DC converter of this utility model.

[0030] Figure 5 This is a schematic diagram of the operating mode 4 of the soft-switching high-gain DC-DC converter of this utility model.

[0031] Figure 6 This is a schematic diagram of the operating mode 5 of the soft-switching high-gain DC-DC converter of this utility model.

[0032] Figure 7 This is a schematic diagram of the operating mode 6 of the soft-switching high-gain DC-DC converter of this utility model.

[0033] Figure 8 This is a schematic diagram of the operating mode 7 of the soft-switching high-gain DC-DC converter of this utility model.

[0034] Figure 9 This is a schematic diagram of the operating mode 8 of the soft-switching high-gain DC-DC converter of this utility model. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, they are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the utility model. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings:

[0042] This invention proposes a soft-switching high-gain DC-DC converter based on active clamping and coupled inductors, such as... Figure 1 It includes a first coupled inductor CI-1 and a second coupled inductor CI-2. Both the first coupled inductor CI-1 and the second coupled inductor CI-2 have primary windings and secondary windings. The primary winding inductance includes the first inductor L. P1 Second inductor L P2 The secondary winding inductance includes the third inductor L. S1 and the fourth inductor L S2 The number of turns on the primary side of both the first coupled inductor CI-1 and the second coupled inductor CI-2 is twice the number of turns on the secondary side.

[0043] Input voltage V in The positive terminal is connected to the first inductor L of the first coupling inductor CI-1. P1 The first inductance L of the first coupling inductor CI-1 P1 The first branch at the other end is connected to the first switched capacitor C1, and the second branch is connected to the auxiliary switch S. A The source and the third branch are connected to the drain of the main switch S; the first branch at the other end of the first switching capacitor C1 is connected to the second inductor L of the second coupling inductor CI-2. P2 The second branch connects to the first diode D1; the second inductor L of the second coupling inductor CI-2 P2 The first branch at the other end and the auxiliary switch S A The drains are connected, and the second branch is connected to the clamping capacitor C. C The first branch at the other end of the first diode D1 is connected to the third inductor L of the first coupling inductor CI-1. S1 The second branch is connected to the second diode D2, and the third branch is connected to the output capacitor C. O2 The fourth branch is connected to the output capacitor C. O1 The third inductor L of the first coupling inductor CI-1 S1 The other end is connected to the fourth inductor L of the second coupling inductor CI-2. S2The fourth inductor L of the second coupling inductor CI-2 S2 The other end is connected to the second switched capacitor C2, and the third diode D3 and the other end of the second diode D2 are connected together and then connected to the other end of the second switched capacitor C2; the other end of the third diode D3 is connected to the output capacitor C. O2 The other end is connected to the load resistor R. L Load resistance R L The other end, output capacitor C O1 The other end, clamping capacitor C C At the other end, the source of the main switch S and the input voltage V in After the negative terminal is connected to ground, the auxiliary switch S A A first buffer protection unit is connected in parallel above, and a second buffer protection unit is connected in parallel on the main switch S.

[0044] The first buffer protection unit includes a first parasitic diode D. a and the first parasitic capacitance C a The first parasitic diode D a and the first parasitic capacitance C a Parallel connection in auxiliary switch S A Above. The second buffer protection unit includes a second parasitic diode D. r Second parasitic capacitance C r The second parasitic diode D r Second parasitic capacitance C r It is connected in parallel to the main switch S.

[0045] The drain of the main switch S and the auxiliary switch S A The source terminals are connected, and the auxiliary switch S is connected. A With clamping capacitor C C This forms an active clamping network. Main switch S and auxiliary switch S A All are N-type MOSFETs. N-type MOSFETs are characterized by low on-resistance and fast switching speed, making them suitable for high-frequency soft-switching applications; at the same time, the body diode of the MOSFET can be directly used as the parasitic diode D. a / D r This simplifies the structure of the buffer protection unit and reduces the number of components.

[0046] The capacitance of the first switched capacitor C1 is equal to that of the second switched capacitor C2, which balances the energy transmission between the two paths and avoids voltage fluctuations. The first diode D1, the second diode D2, and the third diode D3 are all Schottky diodes. Schottky diodes have extremely short reverse recovery times (almost zero), which can significantly alleviate the current spikes and losses caused by the reverse recovery of traditional diodes, making them particularly suitable for high-frequency operating scenarios.

[0047] The working process of this utility model is described below:

[0048] The proposed circuit is assumed to operate in continuous conduction mode (CCM) and with ideal power switches and diodes. The voltage across all capacitors is constant.

[0049] Mode 1: such as Figure 2 As shown, the second parasitic capacitance C of the main switch S r The first switching capacitor C1 begins to discharge; the output capacitor C O1 Power is supplied to the load, and the output capacitor C O2 The energy is then used to charge the secondary winding of the coupling inductor and the second switched capacitor C2.

[0050] Mode 2: such as Figure 3 As shown, the second parasitic capacitance C r After the energy is completely discharged, the voltage across the main switch S drops to zero, and its second parasitic diode D... r The circuit is turned on by the energy of the second coupling inductor CI-2 and the first switching capacitor C1; before the end of this mode, the main switch S is turned on under zero voltage conditions.

[0051] Mode 3: such as Figure 4 As shown, the main switch S is fully turned on under ZVS. At this time, the first coupling inductor CI-1 is directly charged by the input voltage, and the second coupling inductor CI-2 is charged by the clamping capacitor Cc; simultaneously, the second switching capacitor C2 is charged through the secondary winding; the two output capacitors C O1 and C O2 They then discharge together to the load.

[0052] Mode 4: such as Figure 5 As shown, when the main switch S is off, its second parasitic capacitance C r Charging begins; the first diode D1 conducts, and the output capacitor C... O1 The load is still supplied by the primary winding of the clamping capacitor Cc and the second coupling inductor CI-2. O2 It is powered by the second switched capacitor C2.

[0053] Mode 5: such as Figure 6 As shown, auxiliary switch S A The first parasitic diode D a Due to the second parasitic capacitance C of the main switch r The voltage causes the circuit to conduct; the primary windings of the two coupled inductors discharge along a predetermined circuit, while the secondary windings and the second switched capacitor C2 discharge to the output capacitor C. O2 Release energy.

[0054] Mode 6: such as Figure 7 As shown, the first diode D1 is turned off; the input voltage, together with the primary winding of the first coupling inductor CI-1, flows to the clamping capacitor C. cDischarge occurs as the primary winding of the coupling inductor CI-2 discharges to the first switching capacitor C1; the output capacitor C... O2 The secondary winding continues to charge via the second switching capacitor C2, while the load is supplied by the output capacitor C. O1 powered by.

[0055] Mode 7: such as Figure 8 As shown, the first diode D1 is turned on again, and the current path is similar to that in mode 5, which is in the steady state stage.

[0056] Mode 8: such as Figure 9 As shown, auxiliary switch S A Under ZVS conditions, the circuit is turned on; the energy stored in the secondary windings of the two coupled inductors is transferred to the output capacitor C through the third diode D3. O2 Discharge; at the same time, the first switching capacitor C1 feeds energy back to the clamping capacitor Cc, completing a full switching cycle.

[0057] A soft-switching high-gain DC-DC converter based on active clamping and coupled inductors significantly reduces the number of components. Through active clamping technology, both the main and auxiliary switches achieve zero-voltage turn-on, thereby greatly reducing switching losses. This converter achieves high voltage gain under low duty cycle conditions, and the gain can be further increased by increasing the turns ratio of the coupled inductor. The active clamping circuit not only suppresses voltage spikes in the switching transistors, reducing device size, cost, and conduction losses, but also recovers the leakage inductance energy of the coupled inductor, significantly alleviating the reverse recovery problem of the diodes.

[0058] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A soft-switching high-gain DC-DC converter based on active clamping and coupled inductors, characterized in that, It includes a first coupled inductor CI-1 and a second coupled inductor CI-2, both of which have primary windings and secondary windings. The primary winding inductance includes a first inductor L. P1 Second inductor L P2 The secondary winding inductance includes the third inductor L. S1 and the fourth inductor L S2 ; Input voltage V in The positive terminal is connected to the first inductor L of the first coupling inductor CI-1. P1 The first inductance L of the first coupling inductor CI-1 P1 The first branch at the other end is connected to the first switched capacitor C1, and the second branch is connected to the auxiliary switch S. A The source and the third branch are connected to the drain of the main switch S; the first branch at the other end of the first switching capacitor C1 is connected to the second inductor L of the second coupling inductor CI-2. P2 The second branch connects to the first diode D1; the second inductor L of the second coupling inductor CI-2 P2 The first branch at the other end and the auxiliary switch S A The drains are connected, and the second branch is connected to the clamping capacitor C. C The first branch at the other end of the first diode D1 is connected to the third inductor L of the first coupling inductor CI-1. S1 The second branch is connected to the second diode D2, and the third branch is connected to the output capacitor C. O2 The fourth branch is connected to the output capacitor C. O1 The third inductor L of the first coupling inductor CI-1 S1 The other end is connected to the fourth inductor L of the second coupling inductor CI-2. S2 The fourth inductor L of the second coupling inductor CI-2 S2 The other end is connected to the second switched capacitor C2, and the third diode D3 and the other end of the second diode D2 are connected together and then connected to the other end of the second switched capacitor C2; the other end of the third diode D3 is connected to the output capacitor C. O2 The other end is connected to the load resistor R. L Load resistance R L The other end, output capacitor C O1 The other end, clamping capacitor C C At the other end, the source of the main switch S and the input voltage V in After the negative terminal is connected to ground, the auxiliary switch S A A first buffer protection unit is connected in parallel above, and a second buffer protection unit is connected in parallel on the main switch S.

2. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The first buffer protection unit includes a first parasitic diode D. a and the first parasitic capacitance C a The first parasitic diode D a and the first parasitic capacitance C a Parallel connection in auxiliary switch S A superior.

3. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The second buffer protection unit includes a second parasitic diode D. r Second parasitic capacitance C r The second parasitic diode D r Second parasitic capacitance C r It is connected in parallel to the main switch S.

4. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The drain of the main switch S and the auxiliary switch S A The source poles are connected.

5. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The auxiliary switch S A With the clamping capacitor C C This forms an active clamping network.

6. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The capacitance value of the first switched capacitor C1 is equal to the capacitance value of the second switched capacitor C2.

7. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The first diode D1, the second diode D2, and the third diode D3 are all Schottky diodes.

8. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The main switch S is an N-type MOSFET.

9. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The auxiliary switch S A It is an N-type MOSFET.

10. The soft-switching high-gain DC-DC converter based on active clamping and coupled inductor according to claim 1, characterized in that, The number of turns on the primary side of both the first coupled inductor CI-1 and the second coupled inductor CI-2 is twice the number of turns on the secondary side.

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