A high-gain dc-dc converter for automotive fuel cells

Abstract

The invention discloses a fuel cell high-gain DC-DC converter used for an automobile, and belongs to the new energy automobile DC-DC converter technology field. The invention aims at solving a problemthat an existing non-isolated DC-DC converter topology used for the fuel cell automobile cannot give consideration to a high gain and a low device voltage stress at the same time. The converter comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a switching tube Q1, a switching tube Q2, a switching tube Q3, a diode D1, a diode D2, a diode D3, a diode D4 and an inductor L. Byusing the DC-DC converter topology of the invention, based on a switching inductor and a switching capacitor network, voltage stresses of all power semiconductor devices and capacitors in a circuit do not exceed half of an output voltage while the high gain is realized, the converter is beneficial to device type selection, the used devices are fewer, and the problem of circuit complexity is overcome.

Description

technical field [0001] The invention relates to the field of converters, in particular to a high-gain DC-DC converter for fuel cells used in automobiles. Background technique [0002] The burning of a large amount of fossil fuels has led to serious energy shortages and environmental pollution problems, and the development of the new energy vehicle industry has brought hope for solving these problems. Due to its advantages of cleanliness, reliability and high efficiency, fuel cell vehicles have become a very promising research direction in the new energy vehicle industry. However, the fuel cell has some defects, such as: the output characteristic of the fuel cell is soft, and the output voltage drops too fast with the increase of the output current; the output voltage of the fuel cell is generally low, and it cannot directly drive the motor of the car. At present, the DC bus voltage of general fuel cell vehicles is relatively high. In order to provide a stable DC bus voltage...

AI Technical Summary

Problems solved by technology

[0004] (1) Traditional Boost, Buck-Boost and interleaved half-bridge topologies are difficult to obtain high gain, and cannot meet the requirements of high gain and wide input voltage range for DC-DC converters used in fuel cell vehicles

In addition, when the boost ratio is large, the duty cycle is close to the limit value 1. This extreme duty cycle makes the turn-on time of the power switch too long, which easily causes the switch tube to work in an unsafe area and increases the on-state loss of the power device.

[0005] (2) High gain can be achieved by using the Boost cascade structure, but the cascade connection of two or more basic converters will cause problems such as complex circuit, large converter size, high cost and low efficiency

[0006] (3) In some non-isolated converter topologies based on switched inductors and switched capacitors, power devices will be subjected to high voltage stress, which is not conducive to device selection

[0007] (4) On the one hand, some existing non-isolated DC-DC converters with non-common ground structures have the problem of bringing difficulties to the sampling of the circuit; on the other hand, when the boost circuit is working normally, the input terminal and High-frequency pulsating voltage is generated between the output terminals, which is likely to cause safety problems and electromagnetic interference, which reduces the reliability of the converter

Images