 the Äuk converter (pronounced chook; sometimes incorrectly spelled cuk, Äuk or cÃºk) is a type of dc-dc converter that has an output voltage magnitude that is either greater than or less than the input voltage magnitude. it is essentially a boost converter followed by a buck converter with a capacitor to couple the energy. the non-isolated Äuk converter can only have opposite polarity between input and output. it uses a capacitor as its main energy-storage component, unlike most other types of converters which use an inductor. it is named after slobodan Äuk of the california institute of technology, who first presented the design. ==non-isolated Äuk converter== there are variations on the basic Äuk converter. for example, the coils may share single magnetic core, which drops the output ripple, and adds efficiency. because the power transfer flows continuously via the capacitor, this type of switcher has minimized emi radiation. the Äuk converter enables the energy flow bidirectionally, by adding a diode and a switch. ===operating principle=== thumb|350px| fig 1: schematic of a non-isolated Äuk converter. thumb|200px| fig 2: the two operating states of a non-isolated Äuk converter. thumb|350px| fig 3: the two operating states of a non-isolated Äuk converter. in this figure, the diode and the switch are either replaced by a short circuit when they are on or by an open circuit when they are off. it can be seen that when in the off state, the capacitor c is being charged by the input source through the inductor l1. when in the on state, the capacitor c transfers the energy to the output capacitor through the inductance l2. a non-isolated Äuk converter comprises two inductors, two capacitors, a switch (usually a transistor), and a diode. its schematic can be seen in figure 1. it is an inverting converter, so the output voltage is negative with respect to the input voltage. the capacitor c is used to transfer energy and is connected alternately to the input and to the output of the converter via the commutation of the transistor and the diode (see figures 2 and 3). the two inductors l1 and l2 are used to convert respectively the input voltage source (vi) and the output voltage source (co) into current sources. at a short time scale an inductor can be considered as a current source as it maintains a constant current. thi
Electrical_power_conversion