Tristate Converters

Abstract

In the continuous inductor current operation the tristate DC/DC converters have three modes. In the first mode, the active switches are on and energy is transferred into the coil. In the second mode, the coil is short-circuited and the current in the coils stays constant, and in the third mode, the free-wheeling diode takes over the current. In the here used concept the active switch of the original converter is replaced by a series connection of two active switches and an additional diode is connected to the connection point of the two electronic switches. The other terminal of the diode is connected to the coil. This concept was originally applied to the Boost converter. In this paper, it is shown that the same idea can be applied to other DC/DC converters and the Buck and the Buck-Boost converters are shown. It is also possible to apply the concept to converters of higher order. Here the Cuk, Zeta, and SEPIC are treated. It is also possible to apply it to quadratic converters and the d-square converter is taken as an example. A converter with a reduced duty cycle is also treated and a modification that avoids the inrush current is also shown. Finally, an improved superlift converter is treated. The position of the zero of the transfer function is exemplarily studied.