Dual switch coupled inductor dc-dc converter

Abstract

The application discloses a double-switch coupled inductance DC-DC converter and belongs to the technical field of power electronic converters, and specifically comprises an input source, a first inductance, a coupled inductance boost unit, an improved active switch unit, a switch capacitor unit, an output filter module, a sixth diode, a sixth capacitor and a load, wherein the improved active switch unit comprises a first diode, a first power switch tube, a second power switch tube and a first capacitor; the switch capacitor unit comprises a fourth diode, a fifth diode, a fourth capacitor and a fifth capacitor; the first capacitor and the first diode form a clamping loop, thereby reducing the voltage stress of the first power switch tube; and the third capacitor, the fifth capacitor and the fourth diode form a clamping loop, thereby reducing the voltage stress of the second power switch tube.

Description

Technical Field

[0001] This invention belongs to the field of power electronic converters, specifically a dual-switch coupled inductor DC-DC converter. Background Technology

[0002] Driven by both global carbon neutrality goals and energy security, energy transition has become an inevitable trend. Compared to traditional fossil fuels, new energy power generation such as photovoltaics has significant ecological and economic advantages. However, its output voltage is often low and susceptible to environmental factors, thus requiring high-gain DC-DC converters to act as the medium to meet the demands of high-performance downstream loads. Therefore, high-gain DC-DC converters have become one of the research hotspots in the field of new energy power generation.

[0003] High-gain DC-DC converters can be broadly classified into two categories: isolated and non-isolated. Isolated boost converters achieve higher voltage gain by adjusting the turns ratio of the high-frequency transformer windings; however, the high-frequency transformer significantly increases the converter's size, weight, and material cost, thus reducing the overall power density. Non-isolated boost converters, on the other hand, do not require stringent electrical isolation regulations and offer simpler structures, more flexible control, and lower costs, making them a key research area in high-gain boost converters and attracting widespread attention from scholars both domestically and internationally. While traditional boost converters have a simple structure, their voltage gain is limited, and the voltage stress on the switching transistors is relatively high. When facing high-boost scenarios, the duty cycle approaches its limit, and losses increase exponentially, severely impacting the converter's performance. In recent years, various scholars have proposed a variety of boost converter schemes. Based on the traditional boost converter, the original switching transistors are replaced with active switching structures, which reduces the voltage stress on the switching transistors. However, the voltage stress on the switching transistors is still relatively high at a large duty cycle. Two traditional boost converters are cascaded to form a quadratic structure, and the original inductor is replaced with an inductor-diode-capacitor boost unit. Although this can improve the voltage gain, the voltage stress on the switching transistors is relatively high. At the same time, the use of multiple inductors may cause electromagnetic interference problems, and the cost and size will also increase significantly. Compared with traditional inductors, coupled inductors are widely used through magnetic integration technology. They can not only reduce the size, but also introduce a new degree of modulation freedom for the voltage gain of the converter—the turns ratio, which greatly improves the voltage gain performance of the converter. However, a leakage inductance absorption circuit needs to be designed to avoid voltage spikes.

[0004] In summary, existing technologies can reduce the voltage stress of switching transistors through active switching structures, but the effectiveness of reducing the voltage stress of switching transistors needs to be further improved; existing technologies can improve voltage gain through switched capacitors and coupled inductors, but the leakage inductance absorption problem of the coupled inductor needs to be designed. Summary of the Invention

[0005] The purpose of this invention is to provide a dual-switch coupled inductor DC-DC converter.

[0006] The technical solution to achieve the objective of this invention is: a dual-switch high-gain coupled inductor DC-DC converter, including an input source V in The components include: first inductor L1, coupled inductor boost unit, improved active switching unit, switched capacitor unit, output filter module, sixth diode D0, sixth capacitor C0, and load R. L The improved active switching unit includes a first diode D1, a first power switch S1, a second power switch S2, and a first capacitor C1; the switched capacitor unit includes a fourth diode D4, a fifth diode D5, a fourth capacitor C4, and a fifth capacitor C5; wherein, the input source V in The positive terminal is connected to one end of the first inductor L1, and the input source V in The negative terminal is simultaneously connected to the source of the first power switch S1, the cathode of the first diode D1, the negative terminal of the fifth capacitor C5, the negative terminal of the sixth capacitor C0, and the load resistor R. L One end of the first power switch S1 is connected to the other end of the first inductor L1, the positive terminal of the first capacitor C1, and the same-name terminal of the primary winding N1 of the coupling inductor; the anode of the first diode D1 is connected to the negative terminal of the first capacitor C1 and the source of the second power switch S2; the drain of the second power switch S2 is connected to the opposite-name terminal of the primary winding N1 of the coupling inductor, the negative terminal of the second capacitor C2, and the negative terminal of the third capacitor C3; the cathode of the second diode D2 is connected to the positive terminal of the second capacitor C2 and the secondary winding N2 of the coupling inductor. The terminals of the coupling inductor are connected to the same-name terminals; the terminals of the coupling inductor secondary winding N2 are simultaneously connected to the negative terminal of the fourth capacitor C4 and the anode of the third diode D3; the cathode of the third diode D3 is simultaneously connected to the anode of the fourth diode D4 and the positive terminal of the third capacitor C3; the cathode of the fourth diode D4 is simultaneously connected to the anode of the fifth diode D5 and the positive terminal of the fifth capacitor C5; the cathode of the fifth diode D5 is simultaneously connected to the positive terminal of the fourth capacitor C4 and the anode of the sixth diode D0; the cathode of the sixth diode D0 is simultaneously connected to the positive terminal of the sixth capacitor C0 and the load resistor R. L The other end is connected; the first power switch S1 and the second power switch S2 are connected by the control signal V gs Synchronous control is used to switch the converter between on and off modes; the primary winding N1 of the coupled inductor and the secondary winding N2 of the coupled inductor form a magnetic coupling.

[0007] Compared with the prior art, the significant advantages of this invention are:

[0008] (1) By improving the traditional active switching unit and combining it with a switching capacitor, this invention solves the problem that the voltage stress of the switching tube in the traditional active switching unit is still relatively high, and achieves a further reduction in the voltage stress of the switching tube. This is beneficial for selecting a low-voltage switching tube with lower on-resistance to reduce losses and improve converter efficiency.

[0009] (2) The converter proposed in this invention has excellent boost capability. By introducing a coupling inductor into the improved active switching unit, a new energy transmission path is constructed, and it is combined with the switched capacitor to form a composite boost unit, which achieves a breakthrough in voltage gain performance. At the same time, the switched capacitor unit can also absorb and utilize leakage inductance energy without the need to introduce an additional leakage inductance absorption circuit, thus improving the efficiency of the system.

[0010] (3) By controlling the simultaneous on and off of two power switching transistors, this invention can change the on / off state of the diodes and the connection method of the coupling inductor and capacitor in the circuit, thereby achieving the effects of absorbing and utilizing leakage inductance and increasing voltage gain.

[0011] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0012] Figure 1 For the existing converter topology.

[0013] Figure 2 To employ an improved active-switch dual-switch coupled inductor DC-DC converter topology

[0014] Figure 3 The equivalent circuit diagram of a dual-switch coupled inductor DC-DC converter using an improved active switch is shown.

[0015] Figure 4 This is an equivalent schematic diagram of the switching mode 1 of a dual-switch coupled inductor DC-DC converter using an improved active switch.

[0016] Figure 5 This is an equivalent schematic diagram of the switching mode 2 of a dual-switch coupled inductor DC-DC converter using an improved active switch.

[0017] Figure 6 This is an equivalent schematic diagram of the switching mode 3 of a dual-switch coupled inductor DC-DC converter using an improved active switch.

[0018] Figure 7 The main waveform diagram is shown for a dual-switch coupled inductor DC-DC converter using an improved active switch.

[0019] Figure 8 This is a dual-switch coupled inductor DC-DC converter topology that uses a traditional active switch.

[0020] Figure 9 This is an equivalent schematic diagram of the switching mode 1 of a dual-switch coupled inductor DC-DC converter using a conventional active switch.

[0021] Figure 10 This is an equivalent schematic diagram of the switching mode 2 of a dual-switch coupled inductor DC-DC converter using a conventional active switch.

[0022] Figure 11 The main waveforms are shown for a dual-switch coupled inductor DC-DC converter using a conventional active switch.

[0023] Figure 12 Comparison of voltage gain when n=1.

[0024] Figure 13 A comparison of normalized voltage stress of the switching transistor when n=1. Detailed Implementation

[0025] like Figure 1 As shown, a dual-switch high-gain DC-DC converter is mainly an improvement on the traditional Boost converter. The original switching transistors are replaced with traditional active switches, reducing the voltage stress on the switching transistors. However, the voltage stress on the switching transistors remains relatively high at large duty cycles. Theoretical analysis yields the voltage gain G1 and the voltage stress V of the two switching transistors. S1 V S2 :

[0026] (1)

[0027] (2)

[0028] like Figure 2 , 3 As shown, a dual-switch coupled inductor DC-DC converter employing an improved active switch is mainly an improvement on the traditional Boost converter. It primarily consists of a coupled inductor boost unit, an improved active switch unit, and a switched capacitor unit. The coupled inductor boost unit includes a second inductor L... k Third inductor L m The system includes: a primary winding N1 of a coupled inductor, a secondary winding N2 of a coupled inductor, a second diode D2, a third diode D3, a second capacitor C2, and a third capacitor C3; the improved active switching unit includes a first diode D1, a first power switch S1, a second power switch S2, and a first capacitor C1; the switched capacitor unit includes a fourth diode D4, a fifth diode D5, a fourth capacitor C4, and a fifth capacitor C5.

[0029] In summary, the dual-switch coupled inductor DC-DC converter with improved active switching proposed in this invention includes an input source Vin First inductor L1, second inductor L k Third inductor L m The coupling inductor consists of: primary winding N1, secondary winding N2, diodes D1, D2, D3, D4, D5, and D0; power switch S1 and S2; capacitors C1, C2, C3, C4, C5, and C0; and a load R. L ; where the input source V in The positive terminal is connected to one end of the first inductor L1, and the input source V in The negative terminal is simultaneously connected to the source of the first power switch S1, the cathode of the first diode D1, the negative terminal of the fifth capacitor C5, the negative terminal of the sixth capacitor C0, and the load resistor R. L One end is connected; the drain of the first power switch S1 is simultaneously connected to the other end of the first inductor L1, the positive terminal of the first capacitor C1, and the second inductor L k One end of the first diode is connected to the anode of the second diode D2; the second inductor L k The other end is connected to the same-name terminal of the primary winding N1 of the coupling inductor; the anode of the first diode D1 is simultaneously connected to the cathode of the first capacitor C1 and the source of the second power switch S2; the drain of the second power switch S2 is simultaneously connected to the opposite-name terminal of the primary winding N1 of the coupling inductor, the cathode of the second capacitor C2, and the cathode of the third capacitor C3; the cathode of the second diode D2 is simultaneously connected to the anode of the second capacitor C2 and the same-name terminal of the secondary winding N2 of the coupling inductor; the opposite-name terminal of the secondary winding N2 of the coupling inductor is simultaneously connected to the cathode of the fourth capacitor C4 and the anode of the third diode D3; the cathode of the third diode D3 is simultaneously connected to the anode of the fourth diode D4 and the anode of the third capacitor C3; the cathode of the fourth diode D4 is simultaneously connected to the anode of the fifth diode D5 and the anode of the fifth capacitor C5; the cathode of the fifth diode D5 is simultaneously connected to the anode of the fourth capacitor C4 and the anode of the sixth diode D0; the cathode of the sixth diode D0 is simultaneously connected to the anode of the sixth capacitor C0 and the load resistor R. L The other end is connected; the first power switch S1 and the second power switch S2 are connected by the control signal V gs Synchronous control is used to switch the converter between on and off modes; the primary winding N1 and the secondary winding N2 of the coupled inductor form a magnetic coupling; the first capacitor C1 and the first diode D1 form a clamping circuit to reduce the voltage stress on the first power switch S1; the third capacitor C3, the fifth capacitor C5 and the fourth diode D4 form a clamping circuit to reduce the voltage stress on the second power switch S2.

[0030] In a further embodiment, the control signal Vgs of the dual-switch coupled inductor DC-DC converter with improved active switches simultaneously controls the on / off state of power switches S1 and S2; the entire control process is divided into three switching modes, namely switching mode 1, switching mode 2, and switching mode 3.

[0031] Where, t1 - t0 = DT s =D / f s t3 - t1 = (1 - D)T s =(1-D) / f s , where f s This refers to the switching frequency.

[0032] Mode 1 corresponds to the time period [t0-t1]: Under this mode, such as Figure 4 As shown, the first power switch S1 and the second power switch S2 are simultaneously turned on, the first diode D1, the third diode D3, the fourth diode D4, and the sixth diode D0 are turned off, and the second diode D2 and the fifth diode D5 are turned on. At this time, V in The primary magnetizing inductance of the first inductor L1 is charged by the first capacitor C1, and the leakage inductance current i Lk and excitation current i Lm It shows an upward trend; the fifth capacitor C5 charges the fourth capacitor C4 through the fifth diode D5, and is related to V. in Charge the second capacitor C2 together.

[0033] Mode 2 corresponds to the time period [t1-t2]: Under this mode, as follows Figure 5 As shown, the first power switch S1 and the second power switch S2 are off, the second diode D2 and the fifth diode D5 are off, and the first diode D1, the third diode D3, the fourth diode D4 and the sixth diode D0 are on. At this time, V in The first inductor L1 and the first capacitor C1 are charged, and the primary side of the coupled inductor releases energy to the fifth capacitor C5, resulting in a leakage inductance current i. Lk and excitation current i Lm The current is decreasing; the third capacitor C3 charges the fifth capacitor C5 through the fourth diode D4, and the second capacitor C2 charges the fifth capacitor C5 through the third diode D3, and together with the fourth capacitor C4, charges the load R. L Energy supply.

[0034] Mode 3 corresponds to the time period [t2-t3]: Under this mode, as follows Figure 6 As shown, the first power switch S1 and the second power switch S2 are off, the second diode D2 and the fifth diode D5 are off, and the first diode D1, the third diode D3, the fourth diode D4 and the sixth diode D0 are on. At this time, V inThe first inductor L1 and the first capacitor C1 continue to charge, and the second capacitor C2 charges the third capacitor C3 through the third diode D3. The input power supply V in The first inductor L1, the second capacitor C2, the fourth capacitor C4, and the secondary side of the coupling inductor together transfer energy to the load.

[0035] Applying KVL to the equivalent circuit diagram of the first power switch S1 and the second power switch S2 in switching mode 1 when they are turned on, we can obtain:

[0036] (3)

[0037] Among them, V L1 V Lm V N2 These represent the first inductor L1 and the third inductor L2 when the switching transistor is turned on. m And the voltage on the secondary side of the coupled inductor.

[0038] Applying KVL to the equivalent circuit diagrams of switching modes 2 and 3 when the first power switch S1 and the second power switch S2 are turned off, we can obtain:

[0039] (4)

[0040] in, These represent the first inductor L1 and the third inductor L2 when the switching transistor is turned off. m And the voltage on the secondary side of the coupled inductor.

[0041] During one switching cycle, the first inductor L1 and the third inductor L... m Using the volt-second balance, we can obtain:

[0042] (5)

[0043] Substituting formulas 3 and 4 into the above equation, we can obtain the expressions for the voltages of each capacitor:

[0044] (6)

[0045] Substituting the above formula into Formula 2, we obtain the output voltage V0, which is the voltage gain expression:

[0046] (7)

[0047] Without considering the effect of leakage inductance, i.e., k=1, we can obtain the simplified expression for voltage gain:

[0048] (8)

[0049] By combining the equivalent circuit diagrams of the converter in each operating mode, the drain-source voltage V when the first power switch S1 and the second power switch S2 are turned off can be obtained. ’ S1 V ’ S2 :

[0050] (9)

[0051] like Figure 8 As shown, a dual-switch coupled inductor DC-DC converter topology using conventional active switches is mainly an improvement on the conventional Boost converter. It mainly consists of a coupled inductor boost unit, a conventional active switch unit, and a switched capacitor unit. The conventional active switch unit includes a first diode D1, a seventh diode D6, a first power switch S1, a second power switch S2, and a first capacitor C1.

[0052] The control signal Vgs of the dual-switch coupled inductor DC-DC converter simultaneously controls the on / off state of power switches S1 and S2; the entire control process is divided into two switching modes, namely switching mode 1 and switching mode 2.

[0053] Where, t5 - t4 = DT s =D / f s t6 - t5 = (1 - D)T s =(1-D) / f s , where f s This refers to the switching frequency.

[0054] Mode 1 corresponds to the time period [t4-t5]: Under this mode, as follows Figure 9 As shown, the first power switch S1 and the second power switch S2 are simultaneously turned on, the first diode D1, the fourth diode D4, the sixth diode D0, and the seventh diode D6 are turned off, and the second diode D2, the third diode D3, and the fifth diode D5 are turned on. At this time, V in The first inductor L1 is charged, and the primary magnetizing inductance of the coupling inductor is charged by the first capacitor C1. The leakage inductance current i Lk and excitation current i Lm It shows an upward trend; the fifth capacitor C5 charges the fourth capacitor C4 and the third capacitor C3 through the fifth diode D5, and is related to V. in Charge the second capacitor C2 together.

[0055] Mode 2 corresponds to the time period [t5-t6]: Under this mode, as follows Figure 10As shown, the first power switch S1 and the second power switch S2 are off, the second diode D2, the third diode D3, and the fifth diode D5 are off, and the first diode D1, the fourth diode D4, the sixth diode D0, and the seventh diode D6 are on. At this time, V in The first inductor L1 and the first capacitor C1 are charged, and the primary side of the coupled inductor releases energy to the fifth capacitor C5, resulting in a leakage inductance current i. Lk and excitation current i Lm The trend is downward; the third capacitor C3 charges the fifth capacitor C5 through the fourth diode D4, and the second capacitor C2 and the fourth capacitor C4 together charge the load R. L Energy supply.

[0056] Applying KVL to the equivalent circuit diagram of the first power switch S1 and the second power switch S2 in switching mode 1 when they are turned on, we can obtain:

[0057] (10)

[0058] Among them, V L1 V Lm V N2 These represent the first inductor L1 and the third inductor L2 when the switching transistor is turned on. m And the voltage on the secondary side of the coupled inductor.

[0059] Applying KVL to the equivalent circuit diagram of the first power switch S1 and the second power switch S2 in switching mode 2 when they are turned off, we can obtain:

[0060] (11)

[0061] in, These represent the first inductor L1 and the third inductor L2 when the switching transistor is turned off. m And the voltage on the secondary side of the coupled inductor.

[0062] During one switching cycle, the first inductor L1 and the third inductor L... m Using the volt-second balance, we can obtain:

[0063] (12)

[0064] Substituting Equations 10 and 11 into the above equation, we can obtain the expressions for the voltages of each capacitor:

[0065] (13)

[0066] Substituting the above formula into Formula 11, we obtain the output voltage V0, which is the voltage gain expression:

[0067] (14)

[0068] By combining the equivalent circuit diagrams of the converter in each operating mode, the drain-source voltages of the first power switch S1 and the second power switch S2 when they are turned off can be obtained. , :

[0069] (15)

[0070] like Figure 12 The figure shown is a voltage gain comparison graph. From the graph, we can see that... Figure 1 The voltage gain of the converter only approaches that of the converter proposed in this invention when the duty cycle is close to the limit. At the same time, compared with the dual-switch coupled inductor DC-DC converter using conventional active switches, the voltage gain of the dual-switch coupled inductor DC-DC converter using improved active switches is significantly higher, achieving up to 18 times the voltage gain at a duty cycle D=0.5.

[0071] like Figure 13 The figure shows a comparison of normalized voltage stress of the switching transistor. From the figure, we can see... Figure 1 Although conventional active switches are used in dual-switch coupled inductor DC-DC converters to reduce switching voltage stress, the voltage stress remains relatively high at larger duty cycles. This invention, through topology reconstruction and improvements to the conventional active switches, successfully achieves a further reduction in the voltage stress of both switching transistors. Specifically, at a duty cycle D=0.5, the voltage stress of S1 and S2 in a dual-switch coupled inductor DC-DC converter using conventional active switches is 14.28% and 28.57% of the output voltage, respectively, while in a dual-switch coupled inductor DC-DC converter using improved active switches, the voltage stress of S1 and S2 is 11.11% and 22.22% of the output voltage, respectively.

[0072] This invention is based on the traditional Boost converter. To address the shortcomings of the traditional Boost converter, it innovatively combines an active switch, a coupled inductor, and a switched capacitor unit into the traditional Boost converter and improves the traditional active switch. This combination can not only further improve the voltage gain, but also further reduce the voltage stress of the switching transistor. At the same time, it also has the advantages of continuous input current and common input and output ground. It can be applied to new energy power generation systems such as fuel cells and photovoltaic cells.

[0073] This invention improves upon traditional active switches and combines them with switched capacitors, thereby further reducing the voltage stress on the switching transistors. At the same time, by introducing a coupling inductor into the improved active switch unit, a new energy transmission path is constructed, achieving a breakthrough in voltage gain performance and enabling ultra-high voltage gain at low duty cycles.

Claims

1. A dual-switch coupled inductor DC-DC converter, characterized in that, Including input source V in The components include: first inductor L1, coupled inductor boost unit, active switching unit, switched capacitor unit, sixth diode D0, sixth capacitor C0, and load R. L The active switching unit includes a first power switch S1, a second power switch S2, a first capacitor C1, and a first diode D1; the switched capacitor unit includes a fourth diode D4, a fifth diode D5, a fourth capacitor C4, and a fifth capacitor C5; wherein, the input source V in The positive terminal is connected to one end of the first inductor L1, and the input source V in The negative terminal is simultaneously connected to the source of the first power switch S1, the cathode of the first diode D1, the negative terminal of the fifth capacitor C5, the negative terminal of the sixth capacitor C0, and the load resistor R. L One end of the first power switch S1 is connected to the other end of the first inductor L1, the positive terminal of the first capacitor C1, and the same-name terminal of the primary winding N1 of the coupling inductor; the anode of the first diode D1 is connected to the negative terminal of the first capacitor C1 and the source of the second power switch S2; the drain of the second power switch S2 is connected to the opposite-name terminal of the primary winding N1 of the coupling inductor, the negative terminal of the second capacitor C2, and the negative terminal of the third capacitor C3; the cathode of the second diode D2 is connected to the positive terminal of the second capacitor C2 and the secondary winding N2 of the coupling inductor. The terminals of the coupling inductor are connected to the same-name terminals; the terminals of the coupling inductor secondary winding N2 are simultaneously connected to the negative terminal of the fourth capacitor C4 and the anode of the third diode D3; the cathode of the third diode D3 is simultaneously connected to the anode of the fourth diode D4 and the positive terminal of the third capacitor C3; the cathode of the fourth diode D4 is simultaneously connected to the anode of the fifth diode D5 and the positive terminal of the fifth capacitor C5; the cathode of the fifth diode D5 is simultaneously connected to the positive terminal of the fourth capacitor C4 and the anode of the sixth diode D0; the cathode of the sixth diode D0 is simultaneously connected to the positive terminal of the sixth capacitor C0 and the load resistor R. L The other end is connected; the first power switch S1 and the second power switch S2 are connected by the control signal V gs Synchronous control is used to switch the converter between on and off modes; the primary winding N1 of the coupled inductor and the secondary winding N2 of the coupled inductor form a magnetic coupling.

2. The dual-switch coupled inductor DC-DC converter according to claim 1, characterized in that, The dual-switch coupled inductor DC-DC converter achieves three modes by simultaneously controlling the on / off state of the first power switch S1 and the second power switch S2 through a control signal.

3. The dual-switch coupled inductor DC-DC converter according to claim 2, characterized in that, Mode 1 corresponds to the time period [t0-t1]. During this time, the first power switch S1 and the second power switch S2 are simultaneously turned on, the first diode D1, the third diode D3, the fourth diode D4, and the sixth diode D0 are turned off, and the second diode D2 and the fifth diode D5 are turned on. At this time, V in The primary magnetizing inductance of the first inductor L1 is charged by the first capacitor C1, and the leakage inductance current i Lk and excitation current i Lm It shows an upward trend; the fifth capacitor C5 charges the fourth capacitor C4 through the fifth diode D5, and is related to V. in Charge the second capacitor C2 together.

4. The dual-switch coupled inductor DC-DC converter according to claim 2, characterized in that, Mode 2 corresponds to the time period [t1-t2]. During this time, the first power switch S1 and the second power switch S2 are off, the second diode D2 and the fifth diode D5 are off, and the first diode D1, the third diode D3, the fourth diode D4 and the sixth diode D0 are on. At this time, V in The first inductor L1 and the first capacitor C1 are charged, and the primary side of the coupled inductor releases energy to the fifth capacitor C5, resulting in a leakage inductance current i. Lk and excitation current i Lm The current is decreasing; the third capacitor C3 charges the fifth capacitor C5 through the fourth diode D4, and the second capacitor C2 charges the fifth capacitor C5 through the third diode D3, and together with the fourth capacitor C4, charges the load R. L Energy supply.

5. The dual-switch coupled inductor DC-DC converter according to claim 2, characterized in that, Mode 3 corresponds to the time period [t2-t3]. During this time, the first power switch S1 and the second power switch S2 are off, the second diode D2 and the fifth diode D5 are off, and the first diode D1, the third diode D3, the fourth diode D4 and the sixth diode D0 are on. At this time, V in The first inductor L1 and the first capacitor C1 continue to charge, and the second capacitor C2 charges the third capacitor C3 through the third diode D3. The input power supply V in The first inductor L1, the second capacitor C2, the fourth capacitor C4, and the secondary side of the coupling inductor together transfer energy to the load.

6. The dual-switch coupled inductor DC-DC converter according to claim 1, characterized in that, The first capacitor C1 and the first diode D1 form a clamping circuit, thereby reducing the voltage stress on the first power switch S1.

7. The dual-switch coupled inductor DC-DC converter according to claim 1, characterized in that, The third capacitor C3, the fifth capacitor C5, and the fourth diode D4 form a clamping circuit, thereby reducing the voltage stress on the second power switch S2.

8. The dual-switch coupled inductor DC-DC converter according to claim 2, characterized in that, The specific gains for the three switching modes are as follows: ； In the formula, D is the duty cycle of the first power switch S1 and the second power switch S2, and its operating range is (0, 1). The turns ratio of the coupled inductor is n = N2:N1, where N1 and N2 are the windings of the primary and secondary sides of the coupled inductor, respectively.

9. The dual-switch coupled inductor DC-DC converter according to claim 2, characterized in that, The voltage stress on the switching transistor is specifically as follows: ； In the formula, D represents the duty cycle of the first power switch S1 and the second power switch S2, with an operating range of (0, 1). The turns ratio of the coupled inductor is n = N2:N1, where N1 and N2 are the primary and secondary windings of the coupled inductor, respectively. This is the drain-source voltage when the first power switch S1 is turned off. This is the drain-source voltage when the second power switch S2 is turned off.

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