Analysis and Control of Cascade Multiphase DC-DC Boost Converters with Very Low Input Current Ripple

A dc-dc boost converter is commonly used in photovoltaic (PV) power and fuel cell power generation systems. In such applications, a very high voltage gain and very low input current ripple are desirable. One common method to achieve a very high voltage gain is by using a cascade connection of two dc-dc boost converters. In order to reduce the input current ripple, the cascaded converters are multiphase dc-dc boost converters. The phase numbers of the cascaded converters do not have to be the same. Moreover, the duty factors and switching frequencies of the two converters do not also have to be the same. This paper presents how to determine the phase numbers, switching frequencies, and duty factors to maximize the efficiency of the system. This paper also presents how to control the system.