High-voltage-gain low-input-current ripple direct-current converter and working method

Abstract

The invention relates to the technical field of power design, in particular to a high-voltage-gain low-input-current ripple direct-current converter and a working method, and the converter comprises a direct-current input source Vin, an input inductor L, coupling inductors N1 and N2, a switching tube S, diodes D1 to D5, clamping capacitors C1 to C4, an output capacitor Co and a load R; the coupling inductor N1 comprises a primary winding N1a and a secondary winding N1b, the coupling inductor N2 comprises a primary winding N2a and a secondary winding N2b, a terminal 1 of the N1a and a terminal 4 of the N1b are dotted terminals, and a terminal 5 of the N2a and a terminal 8 of the N2b are dotted terminals; according to the invention, ultrahigh output voltage gain can be realized in a limited duty ratio range, the voltage level of the direct current bus is remarkably improved, low-voltage renewable energy can be efficiently and directly connected to the high-voltage direct current bus through single-stage power conversion and the converter, the system architecture is simplified, intermediate conversion links are reduced, and the overall efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric power design, in particular to a high voltage gain and low input current ripple direct current converter and a working method thereof. Background Art

[0002] The voltage level of new energy and energy storage systems is usually low, generally between 20V and 60V. This forms a significant gap with the high voltage requirements in many practical applications. For example, in high-voltage DC bus, new energy grid-connected inverter system and vehicle-mounted inverter, the required DC bus voltage is usually high. Taking the photovoltaic grid-connected inverter system as an example, considering that the grid voltage is 220Vac and there is a voltage fluctuation of ±20%, when using a full-bridge grid-connected inverter, the DC bus voltage needs to reach 380Vdc to 400Vdc, which is much higher than the output voltage of the photovoltaic cell. Therefore, the development of a high-voltage gain DC converter that can realize voltage conversion between a low-voltage new energy power source and a high-voltage DC bus has become a key technical requirement.

[0003] In traditional high-voltage DC bus renewable energy power generation systems, renewable energy or energy storage devices are usually connected to the high-voltage DC bus through multiple cascaded boost DC converters. Although this architecture can achieve voltage boost, it also brings many problems such as high cost, large size and complex control, which seriously affects the economy and integration of the system.

[0004] In order to overcome these shortcomings, researchers have proposed a variety of high voltage gain DC converter solutions in recent years, which can be mainly divided into coupled inductor type and switched inductor / switched capacitor type. Among them, although the high gain DC converter based on switched inductor / switched capacitor can achieve high voltage gain, it has disadvantages such as a large number of devices, large size, and high cost, which is not conducive to the compact design of the system. In contrast, the high gain DC converter based on coupled inductor can realize the integration of magnetic components, showing the advantages of high power density and low cost, and has gradually attracted widespread attention. However, the existing coupled inductor DC converter generally has the problem of large input current ripple, which not only reduces the efficiency of the system, but also has an adverse effect on the stability of the power supply and load.

[0005] Therefore, developing a DC converter with both low input current ripple and high voltage gain can meet the requirements of new energy systems for power quality and reliability while maintaining system high efficiency, low cost and high power density, and has important engineering application value. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the present invention proposes a low input current ripple and high voltage gain DC converter which can realize power conversion between a low voltage renewable energy source and a high voltage DC bus.

[0007] The present invention is achieved through the following technical solutions:

[0008] A high voltage gain and low input current ripple DC converter, comprising a DC input source Vin, an input inductor L, coupled inductors N1 and N2, a switch tube S, diodes D1 to D5, clamping capacitors C1 to C4, an output capacitor Co and a load R;

[0009] The coupled inductor N1 includes a primary winding N1a and a secondary winding N1b, and the coupled inductor N2 includes a primary winding N2a and a secondary winding N2b, and the terminal 1 of N1a and the terminal 4 of N1b, and the terminal 5 of N2a and the terminal 8 of N2b are the same terminals;

[0010] The positive electrode of the DC input source Vin is connected to the clamping capacitor C1, diodes D1 and D2 through the input inductor L, the clamping capacitor C1 is connected to the primary winding of the coupling inductor N2, the primary winding of the coupling inductor N1 is connected to the diode D1, and the clamping capacitor C2 is connected to the negative electrode of the DC input source Vin; the drain of the switch tube S is connected to the primary winding of the coupling inductor N1 and the diode D3, the source of S is connected to the negative electrode of Vin, the diode D3 is connected to the clamping capacitor C3 and the diode D4, the clamping capacitor C3 is connected to the secondary winding of the coupling inductor N2, the diode D4 is connected to the secondary winding of the coupling inductor N1 and the diode D5, the clamping capacitor C4 is connected to the drain of the switch tube S, and the diode D5 is connected to the output capacitor Co and the load R.

[0011] Further, the output voltage gain of the converter is: Wherein n1 represents the turns ratio between the primary and secondary windings of the coupled inductor N1, n2 represents the turns ratio between the primary and secondary windings of the coupled inductor N2, and D represents the on-duty cycle of the switch tube S.

[0012] 3. A method for operating a high voltage gain low input current ripple DC converter, characterized in that it is applicable to the converter as claimed in claims 1-2, and includes two different switching states in one switching cycle, specifically:

[0013] In switch state 1 from t0 to t1, at t0, the switch tube S is turned on, the diodes D1 and D4 are turned on, the diodes D2, D3 and D5 are turned off, the DC input source Vin charges the input inductor L through the loop formed by the diode D1 and the switch S, the inductor current iL rises linearly, the clamping capacitor C1 is connected in parallel with the primary winding N2a of the coupled inductor N2 through the loop formed by the switch tube S and the diode D1, the winding current iL2 rises, the capacitor C2 is connected in parallel with the primary winding N1a of the coupled inductor N1 through the loop formed by the switch tube S, the winding current iL1 rises, and the output capacitor Co is connected in parallel with the load R to supply power to the load;

[0014] In switch state 2 from t1 to t2, at t1, the switch tube S is turned off, the diodes D1 and D4 are cut off, the diodes D2, D3 and D5 are turned on, the DC input source Vin is connected in series with C2 and then connected in parallel with the input inductor L through the loop formed by the diode D2, the inductor current iL decreases linearly, the clamping capacitors C1 and C2 are connected in series to charge the primary winding N2a of the coupled inductor N2 through the diode D2, the winding current iL2 increases, the clamping capacitors C2 and C3 are connected in series to discharge the primary winding N1a of the coupled inductor N1 through the diode D3, the winding current iL1 decreases, and the secondary winding N1b of the coupled inductor N1 discharges to the load through the diode D5.

[0015] Beneficial effects of the present invention:

[0016] (1) The high voltage gain and low input current ripple DC converter proposed in the present invention can achieve ultra-high output voltage gain within a limited duty cycle range, significantly improving the voltage level of the DC bus. Through single-stage power conversion, the converter can efficiently connect low-voltage renewable energy directly to the high-voltage DC bus, simplifying the system architecture, reducing intermediate conversion links, and improving overall efficiency.

[0017] (2) The high voltage gain and low input current ripple DC converter proposed in the present invention can realize continuous input current and significantly reduce input current ripple. It is suitable for renewable energy input occasions, can smoothly process input current, reduce the impact on renewable energy power generation units, and improve the stability and reliability of the system.

[0018] (3) Compared with the traditional multi-stage boost circuit, the high voltage gain and low input current ripple DC converter proposed in the present invention requires fewer components and has a simpler circuit structure, which significantly reduces the material cost and manufacturing complexity of the system. At the same time, while achieving high voltage gain, the voltage stress of the device is also effectively controlled, reducing the demand for high-voltage components, thereby further reducing costs and improving power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 A circuit schematic diagram of a high voltage gain and low input current ripple DC converter proposed by the present invention;

[0021] Figure 2 A control circuit schematic diagram of a high voltage gain and low input current ripple DC converter proposed by the present invention;

[0022] Figure 3 A control circuit schematic diagram b of a high voltage gain and low input current ripple DC converter proposed by the present invention;

[0023] Figure 4 This is a key circuit waveform diagram of a high voltage gain and low input current ripple DC converter proposed by the present invention;

[0024] Figure 5 An equivalent circuit diagram of a switch state 1 of a high voltage gain and low input current ripple DC converter working method proposed by the present invention;

[0025] Figure 6 An equivalent circuit diagram of switch state 2 of a high voltage gain and low input current ripple DC converter working method proposed by the present invention;

[0026] Figure 7 This is a steady-state simulation waveform of a high voltage gain and low input current ripple DC converter proposed by the present invention;

[0027] Figure 8 A schematic diagram of simulation results of a high voltage gain and low input current ripple DC converter proposed by the present invention when the load changes;

[0028] Fig. 9 This is a schematic diagram of simulation results of a high voltage gain and low input current ripple DC converter proposed by the present invention when the input jumps. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] refer to Figure 1The present embodiment proposes a high voltage gain and low input current ripple DC converter, including a DC input source Vin, an input inductor L, a first coupled inductor N1, wherein the first coupled inductor N1 includes a primary winding N1a and a secondary winding N1b, a second coupled inductor N2, wherein the second coupled inductor N2 includes a primary winding N2a and a secondary winding N2b, a switch tube S, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a first clamping capacitor C1, a second clamping capacitor C2, a third clamping capacitor C3, a fourth clamping capacitor C4, an output capacitor Co, and a load R.

[0032] The terminal 1 of the primary winding of the first coupling inductor N1 and the terminal 4 of the secondary winding are the same terminals, and the terminal 5 of the primary winding of the second coupling inductor N2 and the terminal 8 of the secondary winding are the same terminals.

[0033] The positive end of the DC input source is connected to one end of the input inductor L, the other end of L is connected to one end of the first clamping capacitor C1, the anode of the first diode D1 and the anode of the second diode D2, the other end of C1 is connected to the primary terminal 5 of the second coupling inductor N2, and the primary terminal 6 of N2 is connected to the negative end of the DC input source; the cathode of the first diode D1 is connected to the primary terminal 1 of the first coupling inductor N1, the primary terminal 2 of N1 is connected to the cathode of the second diode D2, the cathode of D2 is connected to one end of the second clamping capacitor C2, the other end of C2 is connected to the negative end of the DC input source, and the drain of the switch tube S is connected to the primary terminal 1 of the first coupling inductor N1 and the third The anode of diode D3 and the source of S are connected to the negative end of the DC input source, the cathode of D3 is respectively connected to one end of the third clamping capacitor C3 and the anode of the fourth diode D4, the other end of C3 is connected to the secondary terminal 7 of the second coupling inductor N2, the secondary terminal 8 of N2 is connected to the source of S, the cathode of D4 is respectively connected to the anode of the fifth diode D5 and the secondary terminal 4 of the first coupling inductor N1, the secondary terminal 3 of N1 is connected to one end of the fourth clamping capacitor C4, the other end of C4 is connected to the drain of the switch tube S, the cathode of D5 is respectively connected to one end of the output capacitor Co and the positive end of the load R, the other end of Co is connected to the negative end of R and then connected to the negative end of the DC input source.

[0034] In this embodiment, the switch tube adopts a metal oxide semiconductor field effect transistor MOSFET. For applications with higher power and higher voltage level, the switch tube may also adopt an IGBT.

[0035] Example 2

[0036] This embodiment proposes a control method for a high voltage gain and low input current ripple DC converter based on the first embodiment: the output voltage or input power is controlled by adjusting the duty cycle of the switch tube S.

[0037] refer to Figure 2 The control method adopts a control circuit. When controlling the high-voltage DC bus voltage, a control circuit of a DC converter with low input current ripple and ultra-high output voltage gain includes a subtractor SUM, an error amplifier EA, a comparator CMP, and a NOT gate NO. The positive input of the subtractor SUM is the bus reference voltage Vo_ref, the negative input of the subtractor SUM is the bus sampling voltage Vo, the output is connected to the input of the error amplifier EA, the output of EA is connected to the positive input of the comparator CMP, the negative input of CMP is used to input a sawtooth wave vt, and the output of CMP generates a driving signal for connecting to the gate of the switch tube S, wherein the control circuit first calculates the difference between the actual output voltage Vo of the high-voltage DC bus and the reference voltage Vo_ref through the subtractor SUM, specifically: The positive input of SUM is the bus reference voltage Vo_ref, which represents the preset target voltage; the negative input of SUM is the bus actual sampling voltage Vo, which represents the actual voltage value obtained by the sampling circuit; the output of SUM generates an error signal, which represents the deviation between the actual voltage and the expected voltage. The error signal is transmitted to the error amplifier EA, which amplifies the error signal to generate an amplified error signal, enhances the tiny voltage deviation, and enables the subsequent circuit to respond and adjust the system more sensitively. The output of EA is connected to the positive input of the comparator CMP to provide the amplified error signal. The comparator CMP compares the amplified error signal with a fixed-frequency sawtooth wave signal vt. The sawtooth wave signal is usually used in pulse width modulation (PWM) to determine the conduction time of the switch tube.

[0038] The positive input terminal of CMP is connected to the output terminal of the error amplifier EA to receive the amplified error signal.

[0039] The negative input terminal of CMP receives the sawtooth wave signal vt. The sawtooth wave signal is a periodically changing voltage signal used to modulate the duty cycle of the switch tube.

[0040] When the error signal exceeds the sawtooth wave signal, the comparator CMP outputs a high level and generates a drive signal to trigger the switch tube S to turn on; when the error signal is lower than the sawtooth wave signal, CMP outputs a low level and turns off the switch tube S.

[0041] Through this comparison, the output end of CMP generates a PWM signal, which is used to control the gate of the switch tube S, adjust the switching frequency and duty cycle of S, and thus control the output voltage of the DC converter.

[0042] In this embodiment, a NOT gate NO is provided between the output end of CMP and the gate of the switch tube S to perform inversion processing on the PWM signal according to logic requirements.

[0043] refer to Figure 3 When controlling the input power of renewable energy, a control circuit of a DC converter with low input current ripple and ultra-high output voltage gain includes an MPPT algorithm unit, a subtractor SUM, an error amplifier EA, a comparator CMP, and a NOT gate NO. One input end of the MPPT algorithm unit is the input voltage Vin of the DC converter, the other input end of the MPPT algorithm unit is the input current Iin of the DC converter, the output end of the MPPT algorithm unit is connected to the negative input end of the subtractor SUM, the positive input end of the subtractor SUM is the input voltage Vin of the DC converter, the output end of the subtractor SUM is connected to the input end of the error amplifier EA, the output end of EA is connected to the positive input end of the comparator CMP, the negative input end of CMP is used to input a sawtooth wave vt, and the output end of CMP generates a driving signal for connecting to the gate of the switch tube S. The specific control steps are similar to those for controlling the high-voltage DC bus mentioned above. The difference is that when controlling the input power, the input reference voltage Vin_ref is not a set value, but is obtained by calculating the maximum power point tracking (MPPT) algorithm. The input of the MPPT algorithm is the input voltage and input current of the converter. The core function of the MPPT algorithm unit is to determine the maximum power point of renewable energy (such as photovoltaic cells) under current conditions in real time through calculation, that is, the MPPT algorithm unit receives the input voltage Vin and input current Iin signals from the DC converter. By analyzing the input voltage and input current, the MPPT algorithm unit calculates the voltage reference value Vin_ref corresponding to the maximum power point. This voltage reference value is the voltage that makes the input power reach the maximum value under the current conditions. The subtractor SUM calculates the difference (i.e., error signal) between the current input voltage Vin and the voltage reference value Vin_ref output by the MPPT algorithm unit. Where:

[0044] The positive input terminal of SUM is the actual input voltage Vin of the DC converter;

[0045] The negative input terminal of SUM is the voltage reference value Vin_ref calculated by the MPPT algorithm unit;

[0046] The output of SUM generates an error signal, which indicates the deviation between the current input voltage and the maximum power point voltage;

[0047] The error signal is transmitted to the error amplifier EA, which amplifies the error signal and generates an amplified error signal. The purpose of this step is to enhance the tiny voltage deviation signal so that the subsequent regulation circuit is more sensitive and effective. The comparator CMP compares the amplified error signal with a sawtooth wave signal vt of a fixed frequency to generate a PWM signal to control the switch tube S. The positive input of CMP is connected to the output of the error amplifier EA to receive the amplified error signal. The negative input of CMP receives the sawtooth wave signal vt. The sawtooth wave signal is used for pulse width modulation (PWM) to determine the conduction time of the switch tube S. When the error signal exceeds the sawtooth wave signal, CMP outputs a high level and generates a PWM drive signal to turn on the switch tube S; when the error signal is lower than the sawtooth wave signal, CMP outputs a low level and turns off the switch tube S. Through this comparison, the PWM signal generated by CMP is used to control the gate of the switch tube S to dynamically adjust the duty cycle of S and realize the regulation of the input power. The NOT gate NO is used to invert the PWM signal output by CMP to ensure the correct conduction and shutdown of the switch tube S. If the polarity of the driving signal needs to be adjusted, the NOT gate will perform a logical inversion of the PWM signal between the output of CMP and the gate of the switch tube S.

[0048] like Figure 4 As shown in FIG. 1 , the theoretical waveform of the high voltage gain low input current ripple DC converter after the above control circuit is adopted in this embodiment, wherein vgS is the gate drive signal of the switch tube S, iLk is the current of the first winding in the three-winding coupled inductor, iL is the input inductor current, iL1 and iL2 are the winding currents of the primary windings N1a and N2a of the first coupled inductor and the second coupled inductor respectively. iD1, iD2, iD3, iD4, iD5 are the currents of the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 respectively, with the direction from the anode to the cathode being positive.

[0049] The high voltage gain and low input current ripple DC converter has two different switching states in one switching cycle. The specific working process of the converter is as follows:

[0050] (1) Switching state 1 (t0~t1): The equivalent circuit is as follows Figure 5 As shown, at time t0, the switch tube S is turned on, the diodes D1 and D4 are turned on, the diodes D2, D3 and D5 are turned off, the DC input source Vin charges the input inductor L through the loop formed by the diode D1 and the switch S, the inductor current iL rises linearly, the first clamping capacitor C1 is connected in parallel with the primary winding N2a of the second coupled inductor through the loop formed by S and D1, the winding current iL2 rises, the second clamping capacitor C2 is connected in parallel with the primary winding N1a of the first coupled inductor through the loop formed by S, the winding current iL1 rises, and the output capacitor Co is connected in parallel with the load R to supply power to the load.

[0051] The DC input source Vin charges the input inductor L through the loop formed by the diode D1 and the switch S, so that the current iL of the input inductor L rises linearly, accumulates energy, and provides necessary energy reserves for subsequent conversion. The charging process of the inductor L is a key step in energy storage, providing sufficient energy support for the circuit in the next cycle, and also adjusting the input power by controlling the current of the inductor. The first clamping capacitor C1 is connected in parallel with the primary winding N2a of the second coupled inductor through the loop formed by the switch S and the diode D1. At this time, the current iL2 in the winding N2a rises, and the first clamping capacitor C1 can be connected in parallel to partially transfer its stored energy to the second coupling inductor N2a, thereby increasing the current of N2a, promoting energy accumulation in the inductor, and achieving high voltage gain. The second clamping capacitor C2 is connected in parallel with the first coupling inductor N1a. The second clamping capacitor C2 is connected in parallel with the primary winding N1a of the first coupling inductor through the loop formed by the switch S. At this time, the current iL1 in the winding N1a rises, and the parallel connection of C2 and N1a can transfer part of the capacitor energy storage to N1a, increase the current in the winding, increase the energy reserve in the inductor, and also promote the realization of voltage gain. The output capacitor Co is connected in parallel with the load R to provide electrical energy to the load. At this time, the energy storage in Co stabilizes the output voltage and provides continuous power supply to the load.

[0052] (2) Switching state 2 (t1~t2): The equivalent circuit is as follows Figure 6As shown, at time t1, the switch tube S is turned off, the diodes D1 and D4 are turned off, the diodes D2, D3 and D5 are turned on, the DC input source Vin is connected in series with C2, and then connected in parallel with the input inductor L through the loop formed by the diode D2, the inductor current iL decreases linearly, C1 and C2 are connected in series to charge the second coupled inductor primary winding N2a through D2, the winding current iL2 increases, C2 and C3 are connected in series to discharge the first coupled inductor primary winding N1a through D3, the winding current iL1 decreases, and the first coupled inductor secondary winding N1b discharges to the load through D5. After S is turned off, the DC input source Vin is connected in series with the second clamping capacitor C2, and connected in parallel with the input inductor L through the loop formed by the diode D2, so that the current iL in the inductor L decreases linearly. When the current in the inductor L decreases, the inductor begins to release the stored energy. This energy is partially transferred to the subsequent circuit to promote the voltage gain. At the same time, during the energy transfer process, it is used to stabilize the current on the input side. The first clamping capacitor C1 and the second clamping capacitor C2 are connected in series, and the primary winding N2a of the second coupled inductor is charged through the diode D2, so that the winding current iL2 increases. The series charging process of C1 and C2 increases the current in the winding N2a, further accumulates energy, and also uses the energy transfer between capacitors to achieve the increase of the current of the inductor N2a. The second clamping capacitor C2 and the third clamping capacitor C3 are connected in series, and the primary winding N1a of the first coupled inductor is discharged through the diode D3, so that the winding current iL1 decreases. The discharge process helps to transfer the energy stored in C2 and C3 to N1a, and through the current change of N1a, the voltage is controlled and increased. At the same time, through the energy release, the necessary power support is provided for other parts in the circuit. The secondary winding N1b of the first coupled inductor is discharged to the load through the diode D5. The discharge process of N1b directly powers the load, ensuring that the load can continuously obtain a stable power supply. At this time, the stored energy in N1b is effectively converted into output electrical energy to support the normal operation of the load.

[0053] According to the above equivalent circuit, combined with the volt-second balance principle of coupled inductors, the output voltage gain of the DC converter under ideal conditions can be expressed as:

[0054] Wherein n1 represents the turns ratio between the primary and secondary windings of the coupled inductor N1, n2 represents the turns ratio between the primary and secondary windings of the coupled inductor N2, expressed as N1a:N1b=n1, N2a:N2b=n2, D represents the on-duty cycle of the switch tube S, the larger the duty cycle D is, the larger the output voltage gain is, the larger the turns ratio is, the larger the output voltage gain is, take the duty cycle D=0.5, n1=n2=3, then the output voltage gain of the converter is 36, which can meet the boost demand of renewable energy such as photovoltaic to 400V DC bus.

[0055] Example 3

[0056] This embodiment proposes a method of using PSIM simulation software to perform time domain simulation analysis on a high voltage gain and low input current ripple DC converter.

[0057] The input source Vin uses a constant voltage source with a voltage of 20V, the rated power of the load R is 500W, the output voltage is 400V, the input inductance L=200μH, the excitation inductance Lm=100μH, the leakage inductance of the coupling inductor is ignored, the first clamping capacitor Cx1, the second clamping capacitor Cx2, the third clamping capacitor Cx3, and the fourth clamping capacitor Cx4 are all 100μF, the switching frequency is fs=100kHz, the output filter capacitor Co=200μF, the turns ratio of the first coupling inductor and the second coupling inductor is n1=n2=2, and the system simulation results are as follows:

[0058] like Figure 7 The figure shows the steady-state simulation results of a high voltage gain and low input current ripple DC converter. It can be seen from the simulation results that the steady-state simulation waveform is consistent with the theoretical analysis.

[0059] like Figure 8 The figure shows the simulation results of the high voltage gain and low input current ripple DC converter when the load R jumps between 200W and 400W. It can be seen from the simulation results that the output voltage can continue to remain unchanged at 400V when the load jumps.

[0060] like Fig. 9 The figure shows the transient simulation results of the high voltage gain and low input current ripple DC converter when the input voltage jumps between 20V and 30V. It can be seen from the simulation results that when the input voltage jumps, the output voltage remains constant.

[0061] According to the above theoretical analysis and simulation, it can be seen that the high voltage gain and low input current ripple DC converter proposed by the present invention has the advantages of simple structure, low cost, and high power density, can achieve ultra-high output voltage gain and continuous input current ripple, and the design of the control circuit is simple. Therefore, the converter proposed by the present invention has obvious advantages over the prior art.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A high voltage gain low input current ripple DC converter, characterized in that: It includes a DC input source Vin, an input inductor L, coupled inductors N1 and N2, a switch tube S, diodes D1 to D5, clamping capacitors C1 to C4, an output capacitor Co and a load R; The coupled inductor N1 includes a primary winding N1a and a secondary winding N1b, and the coupled inductor N2 includes a primary winding N2a and a secondary winding N2b, and the terminal 1 of N1a and the terminal 4 of N1b, and the terminal 5 of N2a and the terminal 8 of N2b are the same terminals; The positive electrode of the DC input source Vin is connected to the clamping capacitor C1, diodes D1 and D2 through the input inductor L, the clamping capacitor C1 is connected to the primary winding of the coupling inductor N2, the primary winding of the coupling inductor N1 is connected to the diode D1, and the clamping capacitor C2 is connected to the negative electrode of the DC input source Vin; the drain of the switch tube S is connected to the primary winding of the coupling inductor N1 and the diode D3, the source of S is connected to the negative electrode of Vin, the diode D3 is connected to the clamping capacitor C3 and the diode D4, the clamping capacitor C3 is connected to the secondary winding of the coupling inductor N2, the diode D4 is connected to the secondary winding of the coupling inductor N1 and the diode D5, the clamping capacitor C4 is connected to the drain of the switch tube S, and the diode D5 is connected to the output capacitor Co and the load R.

2. A high voltage gain low input current ripple DC converter according to claim 2, characterized in that: The output voltage gain of the converter is: Wherein n1 represents the turns ratio between the primary and secondary windings of the coupled inductor N1, n2 represents the turns ratio between the primary and secondary windings of the coupled inductor N2, and D represents the on-duty cycle of the switch tube S.

3. A method for operating a high voltage gain low input current ripple DC converter, characterized in that: Applicable to the converter as claimed in claims 1-2, comprising two different switching states in one switching cycle, specifically: In switch state 1 from t0 to t1, at t0, the switch tube S is turned on, the diodes D1 and D4 are turned on, the diodes D2, D3 and D5 are turned off, the DC input source Vin charges the input inductor L through the loop formed by the diode D1 and the switch S, the inductor current iL rises linearly, the clamping capacitor C1 is connected in parallel with the primary winding N2a of the coupled inductor N2 through the loop formed by the switch tube S and the diode D1, the winding current iL2 rises, the capacitor C2 is connected in parallel with the primary winding N1a of the coupled inductor N1 through the loop formed by the switch tube S, the winding current iL1 rises, and the output capacitor Co is connected in parallel with the load R to supply power to the load; In switch state 2 from t1 to t2, at t1, the switch tube S is turned off, the diodes D1 and D4 are cut off, the diodes D2, D3 and D5 are turned on, the DC input source Vin is connected in series with C2 and then connected in parallel with the input inductor L through the loop formed by the diode D2, the inductor current iL decreases linearly, the clamping capacitors C1 and C2 are connected in series to charge the primary winding N2a of the coupled inductor N2 through the diode D2, the winding current iL2 increases, the clamping capacitors C2 and C3 are connected in series to discharge the primary winding N1a of the coupled inductor N1 through the diode D3, the winding current iL1 decreases, and the secondary winding N1b of the coupled inductor N1 discharges to the load through the diode D5.

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