A high-efficiency soft-switching interleaved parallel Boost circuit

Abstract

The high-efficiency soft-switching interleaved parallel Boost circuit of the present invention is composed of two main circuit inductors L1 and L2, two freewheeling diodes D1 and D2, and two power switch tubes S1 and S2 to form an interleaved parallel Boost circuit. The conduction phases of the two Boost circuits differ by 180 degrees. The soft-switching circuit is connected by an auxiliary freewheeling diode D1. S1 、D S2 、D S3 、D S4 , resonant capacitor C r1 、C r2 And auxiliary inductor L S1 、L S2 The present invention adds inductors and capacitors to the traditional interleaved parallel Boost converter without adding any additional active devices. By utilizing the resonance between them, zero voltage or zero current switching conditions are established when the main switch tube is commutating.

Description

Technical Field

[0001] The present invention relates to a DC / DC converter, in particular to an interleaved parallel Boost circuit adopting a passive soft switching technology. Background Art

[0002] In recent years, the shortage of non-renewable resources like oil, coal, and natural gas, as well as the increasingly serious carbon dioxide emissions caused by their combustion, have led to serious international challenges such as global warming, prompting people around the world to seek natural, clean, and renewable energy sources. Solar energy, a naturally abundant energy source, has attracted considerable attention due to its advantages, including being pollution-free, sustainable, and low-cost.

[0003] Photovoltaic power systems (PVPS) provide clean electricity. As a crucial component of these systems, the performance of photovoltaic DC / DC converters plays a crucial role in the energy conversion and transmission of PVPS. MPPT control in PV systems requires high accuracy in voltage and current sampling, minimizing the output ripple of the photovoltaic panels. Therefore, the photovoltaic DC / DC converter must have low current ripple. Furthermore, PV systems are susceptible to external influences, which can cause fluctuations in the output power of the photovoltaic panels. This requires a wide power regulation range for the photovoltaic DC / DC converter to ensure proper operation.

[0004] Converters can improve their conversion efficiency, output power quality, and reliability by considering various aspects, including components and topology. An interleaved parallel boost converter can be considered as two traditional boost circuits interleaved in parallel. This topology evenly divides the input current and power across two identical branches, improving the voltage and current withstand capabilities of the power devices in the circuit. Because the two power switches alternately switch on and off, the circuit's switching frequency can be considered twice the switching frequency, and the input current is the sum of the two branch currents, effectively reducing input current ripple. In an interleaved parallel boost converter, multiple switches share the input current at staggered times, reducing the required switch capacity, lowering their voltage and current stresses, and lowering input current ripple. This improves power supply efficiency and reliability, while also reducing power supply size. Because the interleaved parallel boost converter uses two switching transistors in alternating operation, it increases the circuit's convertible power. Compared to traditional boost converters, it offers advantages and is more suitable as a front-end DC / DC converter for photovoltaic power generation systems.

[0005] The switching tubes of traditional interleaved parallel Boost converters operate in a hard-switching state, resulting in high switching losses. Especially when the switching tubes operate at high frequencies, this leads to problems such as electromagnetic interference and heat dissipation, affecting the converter's power conversion efficiency and, in turn, the power transmission efficiency of the entire photovoltaic power generation system. Further improvements are needed.

[0006] To address these issues, various soft switching technologies have been studied in recent years. These technologies are generally categorized as active and passive. Active soft switching achieves soft switching of the main circuit's switching transistors by adding active components. However, this addition complicates the control strategy and introduces significant circuit losses. Passive soft switching, on the other hand, achieves soft switching of the switching transistors by adding passive components. These components form a resonant network to regulate the voltage and current of the switching transistors. This results in a short resonance time and minimal impact on the circuit's control strategy. This method offers the advantages of simple structure and high reliability. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-efficiency soft-switching interleaved parallel Boost circuit. By adding passive components, the circuit can achieve soft switching of the switch tube while reducing the input current ripple and the voltage and current stress of the switch tube, so as to solve the problem of low power transmission efficiency of the converter under high-frequency operation of the switch tube.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a high-efficiency soft-switching interleaved parallel Boost circuit, comprising a main circuit inductor L1, a main circuit inductor L2, a freewheeling diode D1, a freewheeling diode D2, a power switch tube S1, a power switch tube S2, an auxiliary freewheeling diode D S1 , auxiliary freewheeling diode D S2 , auxiliary freewheeling diode D S3 , auxiliary freewheeling diode D S4 , resonant capacitor C r1 , resonant capacitor C r2 , auxiliary inductor L S1 and auxiliary inductor L S2 ; One end of the main circuit inductor L1 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D1; the drain of the power switch tube S1 is connected to the anode of the freewheeling diode D1, and the source of the power switch tube S1 is connected to the input power supply V i The capacitor C and resistor R are connected in parallel, one end of which is connected to the cathode of the freewheeling diode D1, and the other end is connected to the input power supply V i Negative connection; one end of the main circuit inductor L2 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D2; the drain of the power switch tube S2 is connected to the anode of the freewheeling diode D2, and the source of the power switch tube S2 is connected to the input power supply Vi The negative electrode is connected; one end of the parallel capacitor C and resistor R is connected to the cathode of the freewheeling diode D2, and the other end is connected to the input power supply V i Negative connection; auxiliary freewheeling diode D S1 The anode and resonant capacitor C r1 One end is connected to the auxiliary freewheeling diode D S1 The cathode of the input power supply V i Positive connection, resonant capacitor C r1 The other end is connected to the drain of the power switch tube S1; the auxiliary freewheeling diode D S2 The cathode of the auxiliary freewheeling diode D S1 Anode connection of auxiliary freewheeling diode D S2 The anode and auxiliary inductor L S1 One end is connected to the auxiliary inductor L S1 The other end is connected to the input power supply V i Negative connection; auxiliary freewheeling diode D S3 The anode and resonant capacitor C r2 One end is connected to the auxiliary freewheeling diode D S3 The cathode of the input power supply V i Positive connection, resonant capacitor C r2 The other end is connected to the drain of the power switch tube S2; the auxiliary freewheeling diode D S4 The cathode of the auxiliary freewheeling diode D S3 Anode connection of auxiliary freewheeling diode D S4 The anode and auxiliary inductor L S2 One end is connected to the auxiliary inductor L S2 The other end is connected to the input power supply V i Negative connection.

[0009] Compared with the prior art, the beneficial technical effects of the present invention are:

[0010] (1) The high-efficiency soft-switching interleaved parallel Boost circuit of the present invention uses passive components to achieve soft switching of the circuit power switch tube, reducing circuit losses and improving the power conversion efficiency of the converter; and there is no voltage overshoot when the power switch tube is turned off, and there is no additional voltage stress on the power switch tube and the freewheeling diode;

[0011] (2) The present invention only adds two resonant capacitors, two auxiliary inductors and four auxiliary diodes to the original circuit to achieve soft switching of the power switch tube, with a simple structure and low circuit loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The high-efficiency soft-switching interleaved parallel Boost circuit of the present invention is described in the following embodiments and accompanying drawings.

[0013] Figure 1 This is a topology diagram of a high-efficiency soft-switching interleaved parallel Boost circuit according to a preferred embodiment of the present invention.

[0014] Figure 2 This is a phase equivalent soft-switching Boost circuit of the high-efficiency soft-switching interleaved parallel Boost circuit of the preferred embodiment of the present invention.

[0015] Figure 3 1 is a schematic diagram of the working mode of an equivalent soft-switching Boost circuit in the t0-t1 phase within a switching cycle in a preferred embodiment of the present invention.

[0016] Figure 4 1 is a schematic diagram of the working mode of an equivalent soft-switching Boost circuit in a switching cycle from t1 to t2 in a preferred embodiment of the present invention.

[0017] Figure 5 1 is a schematic diagram of the working mode of an equivalent soft-switching Boost circuit in the stages t2 to t3 within a switching cycle in a preferred embodiment of the present invention.

[0018] Figure 6 1 is a schematic diagram of the working mode of an equivalent soft-switching Boost circuit in the t3-t4 phase within a switching cycle in a preferred embodiment of the present invention.

[0019] Figure 7 1 is a schematic diagram of the working mode of an equivalent soft-switching Boost circuit in a switching cycle from t4 to t5 in a preferred embodiment of the present invention.

[0020] Figure 8 This is a simulation effect diagram of a high-efficiency soft-switching interleaved parallel Boost circuit according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined Figures 1 to 8 The high-efficiency soft-switching interleaved parallel Boost circuit of the present invention is further described in detail.

[0022] The present invention adds inductors and capacitors to the traditional interleaved parallel Boost converter without adding additional active devices. By utilizing the resonance between them, zero voltage or zero current switching conditions are established when the main switch tube commutates.

[0023] Figure 1 Shown is a topology diagram of a high-efficiency soft-switching interleaved parallel Boost circuit according to a preferred embodiment of the present invention.

[0024] See also Figure 1The high-efficiency soft-switching interleaved parallel Boost circuit of this embodiment includes a main circuit inductor L1, a main circuit inductor L2, a freewheeling diode D1, a freewheeling diode D2, a power switch tube S1, a power switch tube S2, an auxiliary freewheeling diode D S1 , auxiliary freewheeling diode D S2 , auxiliary freewheeling diode D S3 , auxiliary freewheeling diode D S4 , resonant capacitor C r1 , resonant capacitor C r2 , auxiliary inductor L S1 and auxiliary inductor L S2 ;

[0025] One end of the main circuit inductor L1 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D1; the drain of the power switch tube S1 is connected to the anode of the freewheeling diode D1, and the source of the power switch tube S1 is connected to the input power supply V i The capacitor C and resistor R are connected in parallel, one end of which is connected to the cathode of the freewheeling diode D1, and the other end is connected to the input power supply V i The negative electrode is connected to form a Boost circuit;

[0026] One end of the main circuit inductor L2 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D2; the drain of the power switch tube S2 is connected to the anode of the freewheeling diode D2, and the source of the power switch tube S2 is connected to the input power supply V i The negative electrode is connected; one end of the parallel capacitor C and resistor R is connected to the cathode of the freewheeling diode D2, and the other end is connected to the input power supply V i The negative electrodes are connected to form another Boost circuit; the conduction phases of the two Boost circuits differ by 180°;

[0027] Auxiliary freewheeling diode D S1 The anode and resonant capacitor C r1 One end is connected to the auxiliary freewheeling diode D S1 The cathode of the input power supply V i Positive connection, resonant capacitor C r1 The other end is connected to the drain of the power switch tube S1; the auxiliary freewheeling diode D S2 The cathode of the auxiliary freewheeling diode D S1 Anode connection of auxiliary freewheeling diode D S2 The anode and auxiliary inductor L S1 One end is connected to the auxiliary inductor L S1 The other end is connected to the input power supply V i The negative electrode is connected to form a soft switch resonant circuit branch; when the power switch tube S1 is turned on, the soft switch resonant circuit branch resonates, and the resonant capacitor Cr1 The energy is transferred to the input end to achieve zero voltage turn-off of the power switch tube S1; the auxiliary inductor L S1 and the resonant capacitor C r1 One end connected to the auxiliary freewheeling diode D S1 The anode of the Boost circuit (power switch S1) is connected to each other, thereby achieving lossless operation of the Boost circuit (power switch S1) in each switching cycle;

[0028] Auxiliary freewheeling diode D S3 The anode and resonant capacitor C r2 One end is connected to the auxiliary freewheeling diode D S3 The cathode of the input power supply V i Positive connection, resonant capacitor C r2 The other end is connected to the drain of the power switch tube S2; the auxiliary freewheeling diode D S4 The cathode of the auxiliary freewheeling diode D S3 Anode connection of auxiliary freewheeling diode D S4 The anode and auxiliary inductor L S2 One end is connected to the auxiliary inductor L S2 The other end is connected to the input power supply V i The negative electrode is connected to form another soft switch resonant circuit branch; when the power switch tube S2 is turned on, the soft switch resonant circuit branch resonates, and the resonant capacitor C r2 The energy is transferred to the input end to achieve zero voltage turn-off of the power switch tube S2; the auxiliary inductor L S2 and the resonant capacitor C r2 One end connected to the auxiliary freewheeling diode D S3 The anode of the Boost circuit (power switch S2) is connected to each other, thereby achieving lossless operation of the Boost circuit (power switch tube S2) in each switching cycle.

[0029] In this embodiment, the auxiliary freewheeling diode D S1 , auxiliary freewheeling diode D S2 , auxiliary freewheeling diode D S3 , auxiliary freewheeling diode D S4 , resonant capacitor C r1 , resonant capacitor C r2 , auxiliary inductor L S1 and auxiliary inductor L S2 Form a soft switching circuit.

[0030] Since the two power switches are switched on and off alternately, the circuit resonance process is short. The soft switching process of the proposed circuit can be analyzed by analyzing the equivalent soft switching Boost circuit of one phase. Figure 2 As shown in Figure 2, there are five modes in this circuit during each switching cycle:

[0031] (1) t0~t1 stage

[0032] like Figure 3 As shown, in this stage, the power switch is turned off, the circuit is in a stable working state, the input current flows to the load through the main inductor L and the freewheeling diode D, and the load energy is provided by the input end. At this time, the resonant capacitor C r The voltage across the two ends is (V o -V i ), the voltage across the load R is V o , V i is the input power supply;

[0033] (2) t1-t2 stage

[0034] At t1, the power switch is turned on, the voltage across the power switch is 0, and the auxiliary freewheeling diode D S2 conduction, resonant capacitor C r and auxiliary inductor L s Producing resonance, such as Figure 4 , when the resonant capacitor C r When the voltage across the two ends is opposite to the input voltage, the auxiliary freewheeling diode D S1 The conduction and resonance end, the following formula is the resonant capacitance C during the resonance process r The voltage across the two ends V Cr and through the auxiliary inductor L s The current i Ls :

[0035]

[0036]

[0037] Therefore, the time of the resonance process can be obtained through analysis:

[0038]

[0039] (3) t2-t3 stage

[0040] At this stage, the power switch tube is still in the on state, and the circuit working state is as follows: Figure 5 , at t3 time, the resonant capacitor C r The voltage at both ends is the negative input voltage, the power switch voltage is clamped, and the auxiliary freewheeling diode D S1 conduction, auxiliary inductor L s The voltage across the two ends is the input voltage, and its energy is released through the input end and flows through the auxiliary inductor L s The current decreases linearly as follows:

[0041]

[0042] (4) T3-T4 stage

[0043] Auxiliary inductor L at time t3 s The discharge is completed, and the circuit is in a steady state. The load energy is provided by the output capacitor C. Figure 6 As shown;

[0044] (5) T4-T5 stage

[0045] At t4, the power switch is turned off, and the main circuit inductor L supplies the resonant capacitor C r Charging until t5, the resonant capacitor C r The voltage across the terminals rises to (V o -V i ), the circuit reaches a stable working state, such as Figure 7 .

[0046] In this embodiment, MATLAB / Simulink is used to simulate and verify the high-efficiency soft-switching interleaved parallel Boost circuit. The simulation parameters are: switching frequency f is 100kHz, input power supply V i is 5.4V, the output voltage V o The voltage is 28V, the duty cycle of the power switch is 0.81, and the rated power is P o It is 60W. Figure 8 is the resonant capacitor C r Voltage across both ends V Cr , the current of the power switch tube I S , voltage U S , and flows through the auxiliary inductor L s The current i Ls The simulation waveform of . Figure 8 As can be seen, soft switching of the power switch tube is achieved. The soft switching circuit charges and discharges the resonant capacitor Cr. When the power switch tube is turned off during each switching cycle, the voltage across it is clamped by the resonant capacitor, limiting its growth rate. Therefore, the soft switching circuit achieves zero-voltage shutdown of the power switch tube, eliminating switching losses in the power switch tube and improving the energy conversion efficiency of the interleaved parallel boost circuit. This provides a new solution for the front-stage DC / DC converter of photovoltaic power generation systems that require high efficiency and low ripple.

[0047] The above content describes the specific embodiments of the present invention in detail. During the specific implementation, the converter parameters such as input and output voltages, steady-state operating point, switch tube model, component parameters, etc. can be selected or changed according to actual needs. It should be emphasized that the present invention is not limited to the specific implementation methods described above. Technicians in relevant professions can make various variations and modifications within the scope of the claims, but this does not affect the essence of the present invention.

Claims

1. A high-efficiency soft-switching interleaved parallel Boost circuit, characterized in that: Including main circuit inductor L1, main circuit inductor L2, freewheeling diode D1, freewheeling diode D2, power switch tube S1, power switch tube S2, auxiliary freewheeling diode D S1 , auxiliary freewheeling diode D S2 , auxiliary freewheeling diode D S3 , auxiliary freewheeling diode D S4 , resonant capacitor C r1 , resonant capacitor C r2 , auxiliary inductor L S1 and auxiliary inductor L S2 ; One end of the main circuit inductor L1 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D1; the drain of the power switch tube S1 is connected to the anode of the freewheeling diode D1, and the source of the power switch tube S1 is connected to the input power supply V i The capacitor C and resistor R are connected in parallel, one end of which is connected to the cathode of the freewheeling diode D1, and the other end is connected to the input power supply V i Negative connection; One end of the main circuit inductor L2 is connected to the input power supply V i The positive electrode is connected to the positive electrode, and the other end is connected to the anode of the freewheeling diode D2; the drain of the power switch tube S2 is connected to the anode of the freewheeling diode D2, and the source of the power switch tube S2 is connected to the input power supply V i The negative electrode is connected; one end of the parallel capacitor C and resistor R is connected to the cathode of the freewheeling diode D2, and the other end is connected to the input power supply V i Negative connection; Auxiliary freewheeling diode D S1 The anode and resonant capacitor C r1 One end is connected to the auxiliary freewheeling diode D S1 The cathode of the input power supply V i Positive connection, resonant capacitor C r1 The other end is connected to the drain of the power switch tube S1; the auxiliary freewheeling diode D S2 The cathode of the auxiliary freewheeling diode D S1 Anode connection of auxiliary freewheeling diode D S2 The anode and auxiliary inductor L S1 One end is connected to the auxiliary inductor L S1 The other end is connected to the input power supply V i Negative connection; Auxiliary freewheeling diode D S3 The anode and resonant capacitor C r2 One end is connected to the auxiliary freewheeling diode D S3 The cathode of the input power supply V i Positive connection, resonant capacitor C r2 The other end is connected to the drain of the power switch tube S2; the auxiliary freewheeling diode D S4 The cathode of the auxiliary freewheeling diode D S3 Anode connection of auxiliary freewheeling diode D S4 The anode and auxiliary inductor L S2 One end is connected to the auxiliary inductor L S2 The other end is connected to the input power supply V i Negative connection.

2. The high-efficiency soft-switching interleaved parallel Boost circuit according to claim 1, wherein: Auxiliary freewheeling diode D S1 , resonant capacitor C r1 , auxiliary freewheeling diode D S2 , auxiliary inductor L S1 The soft switch resonant circuit branch is formed with the power switch tube S1. When the power switch tube S1 is turned on, the soft switch resonant circuit branch resonates, and the resonant capacitor C r1 The energy is transferred to the input end to achieve zero voltage shutdown of the power switch tube S1; Auxiliary freewheeling diode D S4 , resonant capacitor C r2 , auxiliary freewheeling diode D S3 , auxiliary inductor L S2 and the power switch tube S2 to form another soft switch resonant circuit branch; when the power switch tube S2 is turned on, the soft switch resonant circuit branch resonates, and the resonant capacitor C r2 The energy is transferred to the input end to achieve zero voltage turn-off of the power switch tube S2.

3. The high-efficiency soft-switching interleaved parallel Boost circuit according to claim 2, wherein: Auxiliary inductor L S1 and the resonant capacitor C r1 One end connected to the auxiliary freewheeling diode D S1 The anode of the auxiliary inductor L S2 and the resonant capacitor C r2 One end connected to the auxiliary freewheeling diode D S3 The anode of the transistor is connected to achieve lossless operation of the circuit in each switching cycle.

4. The high-efficiency soft-switching interleaved parallel Boost circuit according to claim 2, wherein: For each soft-switching Boost circuit, there are five modes in each switching cycle, as follows: (1) t0~t1 stage In this stage, the power switch is turned off and the circuit is in a stable working state. The input current flows to the load through the main inductor L and the freewheeling diode D. The load energy is provided by the input end. At this time, the resonant capacitor C r The voltage across the two ends is (V o -V i ), V o is the voltage across the load R, V i is the input power supply; (2) t1-t2 stage At t1, the power switch is turned on, and the voltage across the power switch is 0, which is in direct contact with the auxiliary inductor L. s The auxiliary freewheeling diode in series is turned on, and the resonant capacitor C r and auxiliary inductor L s Resonance occurs when the resonant capacitor C r When the voltage across the terminals is opposite to the input voltage, connect the input power supply V i and the resonant capacitor C r The auxiliary freewheeling diode is turned on and the resonance ends. The following formula is the resonant capacitance C during the resonance process. r Voltage across both ends and flows through the auxiliary inductor L s Current The time of the resonance process is: (3) t2-t3 stage At this stage, the power switch is still in the on state, and the resonant capacitor C r The voltage across the two ends is the negative input voltage, the power switch voltage is clamped, and the auxiliary inductor L s The auxiliary freewheeling diode in series is turned on, and the auxiliary inductor L s The voltage across the two ends is the input voltage, and its energy is released through the input end and flows through the auxiliary inductor L s The current decreases linearly as follows: (4) T3-T4 stage Auxiliary inductor L at time t3 s Discharge is completed, the circuit is in steady state, and the load energy is provided by the output capacitor C; (5) T4-T5 stage At t4, the power switch is turned off, and the main circuit inductor L supplies the resonant capacitor C r Charging until t5, the resonant capacitor C r The voltage across the terminals rises to (V o -V i ), the circuit reaches a stable working state.

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