30-03-2017, 04:39 PM
The circuits work best with a constant and specific input. Controlling input to specific subcircuits is crucial to meeting design requirements. The AC-AC conversion can be easily done with a transformer; However dc-dc conversion is not so simple. Voltage diodes and bridges are useful for reducing the voltage by a certain amount, but may be inefficient. Voltage regulators can be used to provide a reference voltage. In addition, the battery voltage decreases as the batteries are discharged, which can cause many problems if there is no voltage control. The most efficient method of regulating the voltage across a circuit is with an dc-dc converter. There are 5 main types of dc-dc converters. Buck converters can only reduce voltage, boost converters can only increase voltage, and Buckboost, Cúk and SEPIC converters can increase or decrease voltage. Some applications of the converters only need to increase or increase the voltage and can simply use the corresponding converters. However, sometimes the desired output voltage will be in the input voltage range. When this is the case, it is usually best to use a converter that can decrease or increase the voltage. Buck-boost converters can be cheaper because they only require a single inductor and a capacitor. However, these converters suffer a lot of ripple from the input current. This ripple can create harmonics; In many applications these harmonics require the use of a large capacitor or an LC filter. This often makes the buck-boost expensive or inefficient. Another problem that can complicate the use of buck-boost converters is the fact that they reverse the voltage. Cúk converters solve both problems using an additional capacitor and inductor. However, both Cú and the buck-boost converter cause large amounts of electrical voltage in the components, this can result in a device failure or overheating. SEPIC converters solve both problems.
