CN-121984352-A - DC-DC boost converter for photovoltaic charging system and application

Abstract

The invention provides a DC-DC boost converter for a photovoltaic charging system and application thereof, and belongs to the technical field of power electronics. The proposed DC-DC boost converter is combined by topology to obtain a novel high-gain converter comprising four inductors, four switching tubes, two diodes and six capacitors. The converter realizes the ZVS of all switching tubes and the natural turn-off of the diodes by enabling two non-input inductors to work in a bidirectional circulation mode, thereby being beneficial to improving the conversion efficiency of the system. Meanwhile, the input inductance of the converter equally divides the input current without a current sensor or complex current sharing control. The invention is particularly suitable for high gain applications requiring high input current ripple, efficiency, power density and cost, such as photovoltaic charging systems.

Inventors

• ZHANG TAO
• ZHANG JUNYAO
• LI LONGXIANG
• QIN LING
• Kong Ruyu
• Cui Qikai
• YANG YU
• YIN ZEYU
• LIN FEI
• LIU PENGYUAN
• LI CHAO
• YAO YING

Assignees

• 南通大学

Dates

Publication Date

20260505

Application Date

20260206

Claims (6)

1. 1. The DC-DC boost converter for the photovoltaic charging system is characterized by comprising a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3 , a fourth capacitor C 4 , a fifth capacitor C 5 , an output capacitor C o , a first inductor L 1 , a second inductor L 2 , a third inductor L 3 , a fourth inductor L 4 , a first diode D 1 , a second diode D 2 , a first switching tube S 1 , a second switching tube S 2 , a third switching tube S 3 and a fourth switching tube S 4 ; The first end of the first inductor L 1 is connected with the first end of the second inductor L 2 and is used as the positive electrode of the input end of the DC-DC boost converter; The second end of the first inductor L 1 is connected with the source electrode of the third switching tube S 3 , the negative electrode of the second capacitor C 2 and the drain electrode of the first switching tube S 1 ; The second end of the second inductor L 2 is connected with the drain electrode of the second switch tube S 2 and the negative electrode of the first capacitor C 1 ; the drain electrode of the third switching tube S 3 is connected with the positive electrode of the third capacitor C 3 and the first end of the third inductor L 3 ; the second end of the third inductor L 3 is connected with the anode of the first diode D 1 and the anode of the second capacitor C 2 ; The cathode of the first diode D 1 is connected with the source electrode of the fourth switching tube S 4 , the anode of the first capacitor C 1 and the cathode of the fourth capacitor C 4 ; the drain electrode of the fourth switching tube S 4 is connected with the first end of the fourth inductor L 4 and the anode of the fifth capacitor C 5 ; The second end of the fourth inductor L 4 is connected with the anode of the second diode D 2 and the anode of the fourth capacitor C 4 ; The cathode of the second diode D 2 is connected with the anode of the output capacitor C o and is used as the anode of the output end of the DC-DC boost converter; The source electrode of the first switching tube S 1 is connected with the source electrode of the second switching tube S 2 , the negative electrode of the third capacitor C 3 , the negative electrode of the fifth capacitor C 5 and the negative electrode of the output capacitor C o , and is used as the negative electrode of the input end and the negative electrode of the output end of the DC-DC boost converter.
2. 2. The DC-DC boost converter of claim 1, wherein the first inductor L 1 and the second inductor L 2 operate in a current continuous mode and the inductance values satisfy: Where U in,min denotes the lowest input voltage average value, U o denotes the output voltage average value, D max denotes the maximum duty cycle of the drive signal of the switching tube, f s denotes the switching frequency, P o,max denotes the maximum output power, and α denotes the inductor current ripple rate.
3. 3. The DC-DC boost converter of claim 1, wherein the third inductor L 3 and the fourth inductor L 4 operate in a current bi-directional flow mode and the inductance values satisfy: Where I L,val represents the inductor current valley of the first inductor L 1 and the second inductor L 2 , and I o represents the output current average.
4. 4. A DC-DC boost converter according to claim 1, characterized in that the ideal voltage gain G is: Where U in represents the average value of the input terminal voltage, U o represents the average value of the output terminal voltage, and D represents the duty ratio of the driving signal of the switching transistor.
5. 5. Use of a DC-DC boost converter according to any one of claims 1-4 in a photovoltaic charging system.
6. 6. A photovoltaic charging system, comprising: the photovoltaic module is used for converting solar energy into direct-current electric energy; a DC-DC boost converter as claimed in claim 1, having an input connected to the output of the photovoltaic module for boosting the voltage of the photovoltaic module; And the input end of the storage battery is connected with the output end of the DC-DC boost converter and is used for storing electric energy.

Description

DC-DC boost converter for photovoltaic charging system and application Technical Field The application relates to the technical field of DC-DC converters, in particular to a DC-DC boost converter for a photovoltaic charging system and application thereof. Background The photovoltaic charging system based on the parallel optimizer not only can reduce the carbon footprint of the electric automobile, but also has the advantages that 1) the maximum power point of each component can be accurately tracked, the maximum power output of the system is realized under complex and changeable illumination conditions, the charging time is shortened, 2) components with different specifications and ageing degrees are allowed to be used in a mixed mode, the flexible expansion capability is realized, and 3) the state monitoring, intelligent scheduling and quick shutdown of the component level can be realized, the operation and maintenance cost is reduced, and the system safety is improved. The photovoltaic interface converter is a core component of the parallel-type optimizer charging system. In order to realize efficient, reliable and economical operation of the charging system, the charging system must meet the following performance requirements that 1) the charging system has extremely strong boosting capability (more than 15 times) to match the output voltage of the photovoltaic module (about 24-48V) and the battery voltage of the electric automobile (400-800V), 2) the charging system has low enough voltage and current stress to reduce switching loss and on-state loss, improve the charging efficiency and shorten the return on investment period, and 3) the charging system has fewer devices and realizes no electrolytic capacitor to reduce the volume of the device and improve the reliability of the system and reduce the initial investment cost and the operation and maintenance cost. In recent years, many scholars have proposed a number of new interleaved parallel high gain converters. The converter has the advantages of low input current ripple, high voltage gain, low power tube current stress, low voltage stress and the like, but has obvious defects that 1) complicated control is needed to realize interphase inductance current flow equalization, 2) the number of devices is large, partial schemes also have abrupt change of voltage stress along with duty ratio, high voltage-resistant semiconductor devices are needed to be adopted, on-state loss is high, cost is high, 3) all power tubes work in a hard-switching state, and the conversion efficiency of the system is difficult to further improve. Disclosure of Invention In view of this, it is an object of the present invention to provide a DC-DC boost converter for a photovoltaic charging system and applications. Simultaneously, all the switching tubes are enabled to be switched on for ZVS, and all the diodes are enabled to be switched off naturally, so that switching loss is reduced, and the conversion efficiency of the system is improved. In order to achieve the above purpose, the technical scheme provided by the invention is as follows: In a first aspect of the invention, a DC-DC boost converter for a photovoltaic charging system is provided, comprising a first capacitor C 1, a second capacitor C 2, a third capacitor C 3, a fourth capacitor C 4, a fifth capacitor C 5, an output capacitor C o, a first inductor L 1, a second inductor L 2, a third inductor L 3, a fourth inductor L 4, a first diode D 1, a second diode D 2, a first switching tube S 1, a second switching tube S 2, a third switching tube S 3, and a fourth switching tube S 4. The first end of the first inductor L 1 is connected with the first end of the second inductor L 2 and is used as the positive electrode of the input end of the DC-DC boost converter; The second end of the first inductor L 1 is connected with the source electrode of the third switching tube S 3, the negative electrode of the second capacitor C 2 and the drain electrode of the first switching tube S 1; The second end of the second inductor L 2 is connected with the drain electrode of the second switch tube S 2 and the negative electrode of the first capacitor C 1; the drain electrode of the third switching tube S 3 is connected with the positive electrode of the third capacitor C 3 and the first end of the third inductor L 3; the second end of the third inductor L 3 is connected with the anode of the first diode D 1 and the anode of the second capacitor C 2; The cathode of the first diode D 1 is connected with the source electrode of the fourth switching tube S 4, the anode of the first capacitor C 1 and the cathode of the fourth capacitor C 4; the drain electrode of the fourth switching tube S 4 is connected with the first end of the fourth inductor L 4 and the anode of the fifth capacitor C 5; The second end of the fourth inductor L 4 is connected with the anode of the second diode D 2 and the anode of the fourth capacitor C 4; The cathode of th