阅读说明：本技术 一种高增益Boost变换器 (High-gain Boost converter ) 是由 秦岭 张宇妍 周磊 韩启萌 田民 尹铭 沈家鹏 高娟 段冰莹 于 2019-09-09 设计创作，主要内容包括：本发明公开了一种高增益Boost变换器,包括直流电压源、开关管、第一二极管、第二二极管、第一电感、第二电感、第一电容、第二电容、第三电容和负载。本发明所提高增益Boost变换器的电压增益为G＝(1+D)/(1-D),可以在较低的占空比条件下实现较高的电压增益；且所有功率器件的电压应力均为(U<Sub>in</Sub>+U<Sub>o</Sub>)/2,所有电容的电压应力均为(U<Sub>o</Sub>-U<Sub>in</Sub>)/2。与传统二次型Boost变换器相比,相同工况下本发明所提高增益Boost变换器的开关管、部分二极管和电容的电压应力均得到一定程度的降低,且减少了一个二极管,因此降低了系统损耗、器件选型难度和成本,提高了变换效率,较适用于中等升压能力(电压增益G≤9)要求的应用场合,如单相UPS、直流微电网等。(The invention discloses a high-gain Boost converter which comprises a direct-current voltage source, a switching tube, a first diode, a second diode, a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor and a load. The voltage gain of the gain Boost converter is increased to G ═ 1+ D)/(1-D), and the higher voltage gain can be realized under the condition of lower duty ratio; and all the voltage stress of the power devices is (U) in +U o ) (U2) all the capacitors have voltage stress o ‑U in )/2. Compared with the traditional quadratic Boost converter, the voltage stress of a switching tube, partial diodes and a capacitor of the improved gain Boost converter under the same working condition is reduced to a certain degree, and one diode is reduced, so that the system loss, the device model selection difficulty and the cost are reduced, the conversion efficiency is improved, and the improved gain Boost converter is more suitable for application occasions with medium Boost capacity (the voltage gain G is less than or equal to 9), such as a single-phase UPS, a direct-current microgrid and the like.)

1. A high-gain Boost converter is characterized by comprising a direct-current voltage source, a first inductor, a second inductor, a switching tube, a first diode, a second diode, a first capacitor, a second capacitor, a third capacitor and a load, wherein:

the drain electrode of the switching tube is connected with one end of the first inductor, the cathode of the first capacitor and the anode of the first diode;

the anode of the first capacitor is connected with the anode of the second diode and one end of the second inductor;

the other end of the second inductor is connected with the cathode of the second capacitor, the anode of the third capacitor and the cathode of the first diode;

the anode of the second capacitor is connected with the cathode of the second diode and one end of the load;

the positive electrode of the direct current voltage source is connected with the other end of the first inductor and the cathode of the third capacitor, and the negative electrode of the direct current voltage source is connected with the source electrode of the switching tube and the other end of the load;

wherein the first inductor and the second inductor both operate in a current continuous mode.

2. The high-gain Boost converter according to claim 1, wherein the switching tube is an N-channel MOS tube.

3. The high-gain Boost converter according to claim 1, wherein the voltage gain of the high-gain Boost converter is G ═ 1+ D)/(1-D), where D is the on duty cycle of the switching tube.

4. The high-gain Boost converter according to claim 1, wherein the voltage stress of the first capacitor, the second capacitor and the third capacitor of the high-gain Boost converter is (U)_o-U_in) /2, wherein U_inIs the input voltage of the converter, U_oIs the output voltage of the converter.

5. The high-gain Boost converter according to claim 1, wherein the voltage stress of the switching tube, the first diode and the second diode of the high-gain Boost converter is (U)_in+U_o) /2, wherein U_inIs the input voltage of the converter, U_oIs the output voltage of the converter.

Technical Field

The application relates to the field of electrical technology, in particular to a high-gain Boost converter.

Background

With the gradual exhaustion of traditional fossil energy and the increasing severity of problems of environmental pollution, global warming and the like, the development and utilization of new energy with the characteristics of wide resource distribution, large development potential, small environmental impact, sustainable utilization and the like are more and more emphasized by people. At present, photovoltaic power generation, wind power generation, fuel cell power generation and the like are mainly applied to new energy power generation systems. The output voltage of modules such as a photovoltaic module, a fuel cell, a storage battery and the like is lower and is generally 30-48V, and the input voltage required by a half-bridge/full-bridge grid-connected inverter is generally more than 380/760V. A plurality of photovoltaic cell assemblies or fuel cells are connected in series, so that the requirement of the input voltage of a rear-stage inverter can be met, but the whole system cannot work normally easily due to the failure of a certain unit. If the new energy power generation system adopts a two-stage structure in which a DC/DC boost converter having a high boosting capability is cascaded with a voltage source inverter, the above problem will be readily solved. A typical Boost converter is a Boost converter. Due to the limitation of parasitic resistance of the boost inductor, the practical boost capability is very limited (G ≦ 5). Moreover, even if a voltage boost of 8 times or more can be achieved, the duty cycle of the switching tube needs to be increased to 0.88 or more, which leads to a serious drop in system efficiency.

In order to effectively increase the voltage gain of the DC converter, many researchers have proposed various DC/DC converter topologies with high boosting capability. The isolation converter or the boost converter with the coupling inductor has the problems of heavy volume, high cost, leakage inductance, parasitic capacitance and the like; the Boost converter cascade system has two-stage energy conversion, the overall efficiency is low, and the topology and stability design is complex. The quadratic Boost converter shown in fig. 1 has the same gain as the cascade Boost converter, reduces the number of switching tubes, and reduces the control difficulty of the system, but the number of diodes is large, and the voltage stress of the power tube and the capacitor is large, thereby increasing the difficulty and the cost of device model selection.

Disclosure of Invention

In view of the above, the present invention provides a high-gain Boost converter. The high-gain Boost converter provided by the invention can realize high gain under a lower duty ratio; compared with the traditional quadratic Boost converter, the direct current Boost converter has the advantages that one diode is reduced, and the switching tube, part of the diode and the capacitor have lower voltage stress, so that the loss is reduced, and the cost is saved.

In order to achieve the above object, the present invention provides a high-gain Boost converter, including a dc voltage source, a first inductor, a second inductor, a switching tube, a first diode, a second diode, a first capacitor, a second capacitor, a third capacitor, and a load, wherein:

the drain electrode of the switching tube is connected with one end of the first inductor, the cathode of the first capacitor and the anode of the first diode;

the anode of the first capacitor is connected with the anode of the second diode and one end of the second inductor;

the other end of the second inductor is connected with the cathode of the second capacitor, the anode of the third capacitor and the cathode of the first diode;

the anode of the second capacitor is connected with the cathode of the second diode and one end of the load;

the positive electrode of the direct current voltage source is connected with the other end of the first inductor and the cathode of the third capacitor, and the negative electrode of the direct current voltage source is connected with the source electrode of the switching tube and the other end of the load;

the first inductor and the second inductor work in a current continuous mode;

the voltage gain of the high-gain Boost converter is G ═ 1+ D)/(1-D), wherein D is the conduction duty ratio of the switching tube;

furthermore, the switch tube is an N-channel MOS tube.

Further, the voltage stress of the switch tube, the first diode and the second diode is (U)_in+U_o) /2, wherein U_inIs the input voltage of the high-gain Boost converter, U_oIs the output voltage of the high-gain Boost converter.

Further, the voltage stress of the first capacitor, the second capacitor and the third capacitor is (U)_in-U_o)/2。

Compared with the prior art, the technical scheme of the invention has the following advantages:

compared with the traditional quadratic Boost converter, the high-gain Boost converter provided by the invention reduces an anti-reverse diode, so that reverse recovery loss and on-state loss caused by the diode are avoided; the switch tube and the second diode have lower voltage stress, so that the switch tube and the diode with lower price and lower rated voltage can be adopted under the condition of the same input and output voltage, thereby reducing the on-state resistance of the switch tube and the on-state voltage drop of the diode, and reducing the on-state loss and the cost of the converter; the voltage stress of the second capacitor is lower, so that in the application occasion of high output voltage, the second capacitor can adopt a single capacitor with low rated voltage without adopting a plurality of capacitors for serial voltage division, thereby obviously reducing the number of capacitors, the volume of a system and the cost. In addition, the voltage stress of the first capacitor, the second capacitor and the third capacitor is the same, so that the difficulty of purchasing the device is reduced. The converter provided by the invention is more suitable for application occasions with medium boost capability (G is less than or equal to 9), such as single-phase UPS, direct current micro-grid and the like.

Drawings

Fig. 1 is a schematic circuit diagram of a conventional quadratic Boost converter;

fig. 2 is a schematic circuit diagram of a high-gain Boost converter according to an embodiment of the present invention;

fig. 3 is two schematic diagrams of the high-gain Boost converter shown in fig. 2 operating in one switching cycle; fig. 3(a) is a working schematic diagram of the high-gain Boost converter when the switching tube is turned on in one switching period; fig. 3(b) is a working schematic diagram of the high-gain Boost converter when the switching tube is turned off in one switching period;

FIG. 4 is a voltage gain plot for the high-gain Boost converter of FIG. 2;

FIG. 5 is a simulated waveform diagram of the high-gain Boost converter shown in FIG. 2, wherein FIG. 5(a) shows a driving signal u of the switch tube S_gsInductor current i_L1And i_L2Input voltage u_inOutput voltage u_oFig. 5(b) shows a simulated waveform of the switching tube S and the first diode D₁A second diode D₂A first capacitor C₁A second capacitor C₂And a third capacitance C₃The terminal voltage of (1) simulates a waveform diagram.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 2, fig. 2 is a schematic circuit diagram of a high-gain Boost converter according to an embodiment of the present invention. The high-gain Boost converter comprises a direct-current voltage source U_inA first inductor L₁A second inductor L₂A switch tube S and a first diode D₁A second diode D₂A first capacitor C₁A second capacitor C₂A third capacitor C₃And a load R, wherein: drain electrode of switch tube S and first inductor L₁One terminal of (1), a first capacitor C₁And a first diode D₁The anode of (2) is connected; a first capacitor C₁Anode of and a second diode D₂Anode of, second inductor L₂Is connected with one end of the connecting rod; second inductance L₂And the other end of the first capacitor C₂Cathode and third capacitor C₃And the first diode D₁The cathode of (a) is connected; second capacitor C₂Anode of and a second diode D₂Is connected with one end of a load R; positive pole of DC voltage source and first inductance L₁The other end of the first end of the second end of the first,Third capacitor C₃The cathode of the direct-current voltage source is connected with the source electrode of the switching tube S and the other end of the load R; wherein, the first inductance L₁And a second inductance L₂Are operated in a current Continuous Conduction Mode (CCM).

In the invention, the switch tube S preferably adopts an N-channel MOS tube, and the on-state loss of the switch tube is smaller than that of a current control type switch tube.

The operation of the high-gain Boost converter according to the present application is described below with reference to the circuit connection of fig. 2.

The switch tube S has an on-time of T_on＝DT_sWhere D is the duty cycle, T_s＝1/f_sFor a switching period, f_sIs the switching frequency. L is₁Is the inductance of the first inductor, L₂The inductance of the second inductor; c₁Is the capacitance of the first capacitor, C₂Is the capacitance of the second capacitor, C₃The capacitance of the third capacitor.

Specifically, the high-gain Boost converter shown in fig. 2 is divided into two operating states according to the on and off states of the switching tube S, and the operating principle of the high-gain Boost converter provided by the present invention is described below with reference to fig. 3(a) and 3(b), where fig. 3(a) is an operating principle diagram of the high-gain Boost converter shown in fig. 2 when the switching tube S is on, and fig. 3(b) is an operating principle diagram of the high-gain Boost converter shown in fig. 2 when the switching tube S is off.

A first inductor current i when the switch tube S is in the on state_L1A second inductor current i_L2And (4) increasing linearly. First diode D₁A second diode D₂Reverse bias, first capacitor C₁Charging, second capacitor C₂And a third capacitance C₃And (4) discharging. At this time, there are:

in the formula of U_C1And U_C2The terminal voltages of the first capacitor and the second capacitor are respectively.

The first diode D is connected with the switch tube S₁A second diode D₂Is conducted to form a first inductor L₁A second inductor L₂Provides a freewheeling path. A first capacitor C₁Discharging, second capacitor C₂A third capacitor C₃And (6) charging. At this time, there are:

when the circuit is in steady-state operation, according to the first inductance L₁The volt-second equilibrium of (a) is as follows:

U_inDT_s＝(U_o-U_C1-U_in)(1-D)T_s (5)

according to the second inductance L₂The volt-second equilibrium of (a) is as follows:

(U_o-U_C1-U_C2)DT_s＝U_C1(1-D)T_s (6)

as can be seen from fig. 2:

U_C1＝U_C2 (7)

from equation (5) -equation (7), the voltage gain G of the converter can be obtained:

fig. 4 shows theoretical and simulated values of the voltage-gain curve of the high-gain Boost converter shown in fig. 2 in CCM mode. It can be seen that the two are basically consistent, thereby verifying the correctness of the voltage gain formula of the invention. In addition, fig. 4 also shows a gain curve of the conventional Boost converter. It can be seen that the high-gain Boost converter provided by the application has an obvious voltage gain advantage, and the larger the duty ratio is, the more obvious the advantage is, and the converter is verified to realize high gain.

From formulas (6) and (7), it is possible to obtain:

from formula (8):

by substituting formula (10) for formula (9), it is possible to obtain:

further, as can be seen from fig. 2:

switch tube S and first diode D₁The voltage stress of (a) is:

second diode D₂The voltage stress of (a) is:

it can be seen that all power tube voltage stresses of the high-gain Boost converter provided by the invention are equal to (U)_in+U_o) (ii)/2, the voltage stress of all capacitors is equal to (U)_o-U_in)/2。

Table 1 compares the voltage stress of the power transistor and the capacitor of the high-gain Boost converter provided by the present invention and the conventional quadratic Boost converter as shown in fig. 1. It can be seen that the same input voltage U_inAnd an output voltage U_oUnder the conditions ofThe voltage stress of the switching tube, the second diode and the second capacitor of the high-gain Boost converter provided by the invention is reduced to a certain extent. Suppose U_in＝48V，U_o300V, in the Boost converter with increased gain of the invention, the switch tube S and the first diode D₁And a second diode D₂The voltage stress of (48+300)/2 ═ 174V. Therefore, IRFP4768 with a withstand voltage of 250V, an on-state resistance of 17.5m omega and a unit price of 20 yuan can be used as S; d₁And D₂MBR20250CT can be used, and has a pressure resistance of 250V, a forward conduction voltage drop of 0.7V and a unit price of 1.5 yuan. In the conventional quadratic Boost converter shown in fig. 1, the voltage stress of S is 300V, IPB60R040C7 can be selected, the voltage resistance is 600V, the on-state resistance is 40m Ω, and the unit price is 56 yuan; d₁Voltage stress of 120V, D₃The voltage stress of the voltage is 180V, both can adopt MBR20250CT, the withstand voltage is 250V, the forward conduction voltage drop is 0.7V, and the unit price is 1.5 yuan; d₂The voltage stress of the material is 300V, S30L60 can be selected, the voltage resistance is 600V, the forward conduction voltage drop is 1.5V, and the unit price is 2 yuan. Obviously, the converter provided by the invention reduces one diode, and the voltage stress of the switching tube and the second diode is obviously reduced, so that the switching tube with lower on-state resistance and the diode with lower on-state voltage drop can be selected, the system cost is reduced, the system loss is reduced, and the conversion efficiency is improved. In addition, in the Boost converter with increased gain according to the present invention, the first capacitor C₁A second capacitor C₂And a third capacitance C₃The voltage stress of the capacitor is 126V, and an electrolytic capacitor with the rated voltage of 160V can be selected. In the conventional quadratic Boost converter shown in fig. 1, the capacitor C₁The voltage stress of the capacitor is 120V, and an electrolytic capacitor with the rated voltage of 160V needs to be selected; capacitor C₂The voltage stress of the capacitor is 300V, an electrolytic capacitor with the rated voltage of 400V needs to be selected, and the price is generally high. It can be seen that although the converter provided by the invention adopts three capacitors, the rated voltages of the three capacitors are the same and all the capacitors are very low, so that the total cost of the capacitors is not increased. In conclusion, the converter provided by the invention can reduce the purchasing difficulty and cost of devices and improve the conversion efficiency of the system.

TABLE 1 comparison of voltage stress for power tube and capacitor

In order to verify the high-gain Boost converter provided by the embodiment, the present application also builds a simulation circuit shown in fig. 2, wherein simulation parameters are selected as follows: input voltage U_in48V, switching frequency f_s50kHz, 577.6 omega load resistance R, first inductance L₁720 muH, second inductance L₂6mH, first capacitance C₁6.8 μ F, second capacitance C₂6.8 μ F, third capacitance C₃22 muF, IRFP4768 and diode D are selected as the switch tube S₁、D₂Schottky diode MBR20250CT is chosen.

The simulated waveform when the duty ratio D is 0.778 is shown in fig. 5. Wherein, FIG. 5(a) shows the driving signal u of the switch tube S_gsInductor current i_L1And i_L2Input voltage u_inOutput voltage u_oThe waveform of (2). It can be seen that the first inductance L₁And a second inductance L₂The current of (2) is continuous; input voltage of U_in48V, output voltage U_o380V, and G-U converter voltage gain_o/U_in7.92. The theoretical calculated voltage gain is (1+0.778)/(1-0.778) ═ 8, and the two values are basically identical. This shows that the voltage gain formula of the converter proposed in this embodiment in the inductor current continuous mode is correct, which can achieve much larger gain than that of the conventional Boost converter under the condition of low duty ratio.

FIG. 5(b) shows the switch tube S and the first diode D₁A second diode D₂A first capacitor C₁A second capacitor C₂And a third capacitance C₃The terminal voltage of (1) simulates a waveform. It can be seen that the simulated values of the voltage stress are U respectively_S＝U_D1＝U_D2＝215V，U_C1＝U_C2＝U_C3166V. Which is substantially consistent with the results of the voltage stress principle analysis.

It should be noted that, turning on the switch means providing a high level driving signal to the switch tube, and turning off the switch means providing a low level driving signal to the switch tube. Specifically, the switch control unit transmits a Pulse signal to the controllable switch tube through a Pulse Width Modulation (PWM) technique.

It is noted that, in the present application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea, and not to limit it. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall into the protection scope of the present invention.