Choosing a DC to DC Converter

DC-to-DC converters are one of the most important and common components in electronic devices. They are used in consumer electronics, telecommunications equipment, power electronics, automotive, medical, and industrial applications. Besides providing different voltage levels, these converters can also boost or decrease current. Hence, they are an essential component in designing power electronics, hardware, and robotics. However, when choosing a dc to dc converter for a specific application, engineers must consider factors such as size, cost, and efficiency. Fortunately, the market has many choices available for designers to choose from.

Most dc to dc converters are designed to change the DC input voltage level. They are commonly known as switching regulators because they use a switch to alternately connect or disconnect the input and output circuits. Various switching topologies have been developed to achieve this goal. Each topology has its own advantages and disadvantages. Some have a high voltage gain, but they may not offer an adequate output voltage range. On the other hand, others have low voltage gains but are efficient and compact in size.

One popular dc to dc converter is the push-pull converter (shown in Fig. 7.30). In this type of converter, a pair of inductors and a capacitor form a push-pull structure that allows the inductor to absorb energy from the input source and release it to the output load at a constant current. This type of converter is highly efficient and offers a wide range of output voltage.

Another type of dc to dc converter is called a buck converter. Its operating principle is based on Faraday’s law of induction. When the switch S is in the off state, the inductor L stores energy in its magnetic field. When the control signal S is in the on state, the inductor releases this energy to the load by generating an opposing voltage VL that counteracts the voltage of the source. This decreases the output voltage of the dc to dc converter.

The voltage gain of the buck converter can be improved by using a bidirectional circuit. This type of converter is useful in applications such as regenerative braking of automobiles, where the power from the wheels is used to lower the battery voltage after driving.

A dc to dc converter is often implemented in portable electronic devices such as cellular phones and laptop computers, which are powered by batteries. These portable devices typically have several power-consuming sub-circuits with varying voltage requirements. A dc to dc converter helps to properly distribute and manage power so that each sub-circuit can get the right amount of energy. It can also raise the voltage from a partially lowered battery, which saves space and makes the device more energy-efficient.

A dc to dc converter has both switching and conduction losses. The power losses are calculated by summing the resistance and dissipation of each component in the circuit. The switching loss is estimated by considering the diodes’ cut-in and cut-out voltages, as well as their equivalent series resistances rD1, rD2, and rD3. The conduction loss is calculated by estimating the internal resistance of each inductor and capacitor as well as the power dissipation of the main switch.