CN-122026721-A - Staggered parallel DC-DC boost converter and application thereof in balcony photovoltaic power generation system

Abstract

The invention provides a staggered parallel DC-DC boost converter and application thereof in a balcony photovoltaic power generation system, and belongs to the technical field of power electronic conversion. The converter simplifies a driving and sampling circuit by adopting a common ground design of a switching tube and input-output, can realize ultra-high voltage gain of 4/(1-D) within the range of D >1/3 in a current continuous mode, effectively adapts to wide-range fluctuation of input voltage, can automatically divide inductance current equally, remarkably reduces input current ripple, is beneficial to improving the power generation efficiency of a solar battery, does not need a current sensor or complex current sharing control, and reduces the cost and complexity of a system. The invention realizes high gain, low ripple and low voltage stress on the basis of small number of devices and compact structure, thereby better meeting the comprehensive performance requirement of the balcony photovoltaic interface converter in the aspects of power density, cost and overall efficiency.

Inventors

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

Assignees

• 南通大学

Dates

Publication Date

20260512

Application Date

20260206

Claims (6)

1. 1. The alternating parallel DC-DC boost converter is characterized by comprising two phase branches, wherein each phase branch comprises a switched capacitor module; the switch capacitor module is formed by cascading N switch capacitor units, wherein N is an integer greater than 0; The switch capacitor unit comprises a first diode, a second diode, a first capacitor and a second capacitor, wherein the positive electrode of the first capacitor is connected with the cathode of the first diode and the anode of the second diode; in the switch capacitor module, the anode of a first diode of a1 st switch capacitor unit is marked as a first end of the switch capacitor module, the cathode of a second diode of an N-th switch capacitor unit is marked as a second end of the switch capacitor module, and the cathodes of the first capacitors of the N switch capacitor units are connected to serve as a third end of the switch capacitor module; The first phase leg further comprises a first inductor, a first switching tube and a first leg diode; The first end of the first phase branch switch capacitor module is connected with one end of the first inductor and the drain electrode of the first switch tube, and the second end of the first phase branch switch capacitor module is connected with the anode of the first branch diode; The second phase branch circuit further comprises a second inductor, a second switching tube, an output diode, a second branch circuit capacitor and an output capacitor, wherein the first end of the second phase branch circuit capacitor module is connected with the anode of the second branch circuit capacitor and the cathode of the first branch circuit diode, the second end of the second phase branch circuit capacitor module is connected with the anode of the output diode, and the cathode of the output diode is connected with the anode of the output capacitor to serve as the anode of the output end of the DC-DC boost converter; the other ends of the first inductor and the second inductor are connected and serve as the positive electrode of the input end of the DC-DC boost converter; The source electrode of the first switching tube, the source electrode of the second switching tube and the output capacitor are connected with the third end of the switching capacitor module and serve as cathodes of the input end and the output end of the DC-DC boost converter.
2. 2. A DC-DC boost converter according to claim 1, characterized in that N = 1.
3. 3. A DC-DC boost converter according to claim 2, 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 is the duty cycle of the first switching tube and the second switching tube.
4. 4. Use of a DC-DC boost converter according to any one of claims 1-3 in a balcony photovoltaic power generation system.
5. 5. A balcony photovoltaic power generation system, comprising: A DC-DC boost converter, said DC-DC boost converter being a DC-DC converter according to any one of claims 1-3; the output end of the photovoltaic module is connected with the input end of the DC-DC boost converter; And the direct current side of the DC-AC grid-connected inverter is connected with the output end of the DC-DC boost converter and is used for converting direct current into alternating current.
6. 6. The balcony photovoltaic power generation system of claim 5, wherein the output direct current voltage of the photovoltaic module is 24-60V and the direct current bus voltage of the DC-AC grid-connected inverter is 400V.

Description

Staggered parallel DC-DC boost converter and application thereof in balcony photovoltaic power generation system Technical Field The application belongs to the technical field of converters, and particularly relates to an interleaved parallel DC-DC boost converter and application thereof in a balcony photovoltaic power generation system. Background The balcony photovoltaic power generation is used as an important form of distributed energy utilization, and has positive significance for improving the energy efficiency of urban buildings and promoting the on-site consumption of renewable energy sources. The system outputs a low DC voltage (typically ranging from 24V to 60V) and fluctuates over a wide range with changes in illumination intensity, while the output current is large (typically 12A or more), while the DC bus voltage required for the grid-connected inverter is high and stable (about 400V), so voltage matching must be achieved by a high-gain DC-DC interface converter that can operate stably over a wide duty cycle range. The converter needs to have both high boost capability, low current stress and low input current ripple. The low input current ripple is not only beneficial to improving the power generation efficiency of the solar cell panel in actual operation, but also can effectively reduce the capacity of the filter capacitor required by the input end, thereby having direct effects of reducing the system cost, reducing the volume and improving the overall reliability. The staggered parallel high-gain conversion technology has become one of the main research directions for realizing the interface function because of being capable of improving the equivalent switching frequency and equally dividing the current of each phase. Particularly, those topologies having an automatic current sharing of the input inductor, requiring no soft start circuit, and having input/output and switching transistors commonly grounded (contributing to simplified sampling driving and suppression of electromagnetic interference) are attracting attention because of simple control and high reliability. However, the voltage gain of the traditional topology under the conventional symmetrical control is generally less than 10 times, the requirement of the balcony photovoltaic power generation system on the ultra-high voltage boosting ratio is difficult to meet, and more importantly, when the input voltage is widely changed to force the duty ratio to be greatly adjusted, the key performances such as the voltage gain, the current sharing characteristic and the like are often obviously reduced. If the coupling inductance is adopted and the gain is improved by adjusting the turn ratio, the leakage inductance problem caused by the coupling inductance with high turn ratio can cause remarkable voltage peak and oscillation, and the conversion efficiency, the device stress and the electromagnetic compatibility are seriously affected. In addition, if a topology with more phases is constructed by a phase expansion or input-parallel output (IPOS) method, although the gain can be improved under a specific working condition, the automatic current sharing capability cannot be maintained in a wide duty ratio variation range required by the system, so that the input current ripple is increased, the voltage gain is reduced, the stress of a switching tube is increased, and meanwhile, the number of power devices and magnetic elements is increased, so that the problems of high system cost and large volume are caused. Disclosure of Invention In view of the above, the present invention aims to provide an interleaved parallel DC-DC boost converter and an application thereof in a balcony photovoltaic power generation system, so as to reduce the number of switching transistors and inductors, obtain extremely strong boost capability, maintain a constant voltage gain expression, maintain a constant voltage stress and achieve accurate balancing of inductor current under the condition of wide variation of duty ratio. In order to achieve the above purpose, the technical scheme provided by the invention is as follows: in a first aspect of the present invention, there is provided an interleaved parallel DC-DC boost converter comprising two phase legs, each phase leg comprising a switched capacitor module; the switch capacitor module is formed by cascading N switch capacitor units, wherein N is an integer greater than 0; The switch capacitor unit comprises a first diode, a second diode, a first capacitor and a second capacitor, wherein the positive electrode of the first capacitor is connected with the cathode of the first diode and the anode of the second diode; in the switch capacitor module, the anode of a first diode of a1 st switch capacitor unit is marked as a first end of the switch capacitor module, the cathode of a second diode of an N-th switch capacitor unit is marked as a second end of the switch capacitor module, and the cathodes of the first capa