A novel lossless snubber for boost converters

Advanced transportation technologies, such as hybrid-electric vehicles, battery-electric vehicles, and fuel cell vehicles, rely on high-power DC/DC converters to interconnect and manage their power systems. Boost converters are especially useful in stepping-up the voltage from a battery or fuel cell to match the electric motor voltage range. However, conventional high-power boost converters are very large and heavy, partly due to the large inductors used in the design. These heavy components negatively affect the fuel economy of the vehicles, add cost to the vehicle, and may add difficulty for packaging. The solution is to implement a method which reduces the switching losses in the converter so that the switching frequency can be increased and hence the size of the inductors, and overall converter, can be reduced. This paper proposes a new lossless snubber circuit that greatly reduces the switching losses of the IGBT in the converter. The circuit uses no additional magnetic components, has a simple control strategy, is relatively low-cost, and is shown to provide a boost in efficiency even while greatly reducing the size of the converter. Thermal considerations are taken into account to provide practical simulation results.