Multi-stage single switch boost converter

Abstract

The invention relates to the field of power electronics, in particular to a multi-stage single switch boost converter which is composed of a Boost circuit and a plurality of Switch-Capacitor networks. Voltages supplied by all the Switch-Capacitor networks are equal. Accumulation of the network voltages is achieved in an interleaving series connection mode, an output voltage is boosted, and the capacity of boosting is high. The converter is provided with only one active switch element, a control circuit is simple, and voltage stress of a switching tube is small and 1/ (1-D) times that of an input voltage. Capacitor voltages of all the Switch-Capacitor networks are equal and 1/ (1-D) times that of the input voltage, stress of the capacitor voltages is small, therefore, the size of the circuit is reduced, and integration is easy.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a multi-stage single-switch boost converter. Background technique [0002] In renewable energy grid-connected power generation, photovoltaic power generation and fuel cell power generation play an important role. However, the output voltages of solar panels and fuel cells are relatively low, which is not enough to achieve the purpose of grid-connected power generation. Therefore, a DC-DC boost converter with a larger boost ratio becomes extremely important. In addition, in order to be suitable for the engineering field, this type of boost converter should also have smaller volume, higher power density and higher efficiency. [0003] At present, in the field of new energy grid-connected power generation, the traditional Boost converter is widely used. However, in practical applications, its boosting capacity is limited, only 6 times the input voltage. If the output voltage is to ...

AI Technical Summary

Problems solved by technology

[0003] At present, in the field of new energy grid-connected power generation, the traditional Boost converter is widely used. However, in practical applications, its boosting capacity is limited, only 6 times the input voltage. If the output voltage is to be continuously increased, the To increase the duty cycle, this will cause the following problems: ①The voltage and current stress of the active switch tube and diode are large; ②The switching loss and diode reverse recovery loss are large, resulting in low conversion efficiency; ③The dv / dt is large, Lead to serious EMI; ④ Poor ability to resist input voltage disturbance and dynamic performance

Although the current device can achieve a better boost effect, the topology is complex, the design of the control circuit is difficult, and there are many inductive components, and the converter is bulky.

Although the existing n-level cascaded Boost converter can achieve high boosting capability, the voltage stress of the switching tube is relatively high, which is equal to the output voltage, which affects the working efficiency of the converter.

Someone proposed the Z-source converter topology, which uses a unique impedance network to couple the main circuit of the converter and the power supply together to obtain unique characteristics that cannot be obtained by traditional voltage source and current source converters, and provides a novel power converter. The transformation concept overcomes the deficiencies of the traditional voltage source and current source converters, but there are deficiencies in the aspects of insufficient boosting capacity, severe start-up shock, and low DC voltage utilization due to intermittent input current.

The method of cascaded quasi-Z source impedance network is used to increase the voltage gain, and the conversion efficiency is high, but the topology of the main circuit and the control circuit are more complicated. How to ensure the stable operation of the cascaded quasi-Z source impedance network is also relatively difficult, and the circuit There are many inductive components and the volume is large

The existing Cuk converter and Sepic converter use voltage bootstrap technology to realize boosting effect. Although the input current ripple and output voltage ripple are small and the control circuit is simple, the boosting capability is limited.

At present, it is also proposed to use coupled inductors to build high-boost converters for fuel cell power generation systems. The use of coupled inductors will cause excessive voltage stress on switching devices, resulting in large operating losses, low efficiency, and more active switching elements in the converter. ,high cost

Although some schemes recorded in the literature can achieve a good boost effect, the topology is relatively complex, the design of the control circuit is difficult, and the utilization rate of the input voltage is low, and the output voltage ripple is large.

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