Different DC to DC Voltage Conversion Methods

A DC power supply is used in most of the appliances where a constant voltage is required. DC stands for Direct Current, in which the current flow is unidirectional. The process of DC conversion can be don be DC Converters.  The charge carriers in DC supply travel in a single direction. Solar cells, batteries and thermocouples are the sources of DC supply. A DC voltage can produce a certain amount of constant electricity, which becomes weak when it travels further longer. An AC voltage from the generator can change their strength when they travel through a transformer.

DC Converters - 24V DC to 9V DC Converter
24V DC to 9V DC Converter

An AC power supply is an Alternating Current, in which the voltage changes instantly with time. In AC supply the charge carriers change their direction periodically. AC supply is used as utility current for household needs. This utility AC current is converted to DC by using a circuitry which consists of a transformer, rectifier and a filter. Similarly, a DC voltage is stepped up or stepped down to desired voltage using such circuitry.

This utility AC current is converted to DC by using a circuitry which consists of a transformer, rectifier and a filter. Similarly, a DC voltage is stepped up or stepped down to desired voltage using such circuitry.

DC-DC Conversion

A DC to DC converter takes the voltage from a DC source and converts the voltage of supply into another DC voltage level. They are used to increase or decrease the voltage level. This is commonly used automobiles, portable chargers and portable DVD players. Some devices need a certain amount of voltage to run the device. Too much of power can destroy the device or less power may not be able to run the device. The converter takes the power from the battery and cuts down the voltage level, similarly a converter step-up the voltage level. For example, it might be necessary to step down the power of a large battery of 24V to 12V to run a radio.

The converter takes the power from the battery and cuts down the voltage level, similarly a converter step-up the voltage level. For example, it might be necessary to step down the power of a large battery of 24V to 12V to run a radio.

Electronic Conversion

DC to DC converters in electronic circuits uses switching technology. Switched mode DC-DC converter converts the DC voltage level by storing the input energy temporarily and then releases that energy at different voltage output. The storage is done either in magnetic field components like an inductor, transformers or electric field components like capacitors. This conversion method can increase or decrease the voltage level.

Switching conversion is more power efficient than linear voltage regulation, which dissipates unwanted power as heat. The high efficiency of a switched mode converter reduces the heat sinking needed and increases battery endurance of portable equipment. Efficiency has increased due to the use of power FETs, which are able to switch more efficiently with lower switching losses at higher frequencies than power bipolar transistors and use less complex drive circuitry. Another improvement in DC-DC converters is done by replacing the flywheel diode with synchronous rectification using a power FET, whose ‘on resistance’ is much lower, which reduces switching losses.

The efficiency of the converter has increased due to the use of power FETs, which are able to switch more efficiently with lower switching losses at higher frequencies than power bipolar transistors and use less complex drive circuitry. Another improvement in DC-DC converters is done by replacing the flywheel diode with synchronous rectification using a power FET, whose ‘on resistance’ is much lower, which reduces switching losses.

Most DC-DC converters are designed to move unidirectionally, from input to output. But the switching regulator topologies can be designed to move bidirectionally by replacing all diodes with independently controlled active rectification. For example, in regenerative braking of vehicles, where power is supplied to the wheels while driving, but supplied with the wheels when braking. Hence a bi-directional conversion is useful.

Magnetic Conversion

In these DC-DC converters, the energy is periodically stored and released from a magnetic field in an inductor or a transformer in a frequency range of 300KHz to 10MHz. By adjusting the duty cycle of the charging voltage the amount of power transferred to a load can be more easily controlled, through this control can also be applied to the input current, the output current or to maintain constant power. The transformer based converter can provide isolation between input and output.

In general, DC-DC converter refers to the following explained switching converters. These circuits are the heart of switched mode power supply. The below explained are the most commonly used circuits.

Non-Isolated Converters

Non-isolated converters are used when the change in the voltage is small. The input and output terminals share a common ground in this circuit. The following are the different types of converters in this group.

The disadvantage is cannot give protection from high electrical voltages and has more noise.

Step-Down (Buck) Converter

A step-down circuit is used to generate a lower voltage than the input. It is also called as a buck. The polarities are same as in the input.

Buck Converter
Buck Converter

Step-Up (Boost) Converter

A step-up circuit is used to generate a higher voltage than the input voltage. It is called as a boost. The polarities are same as in the input.

Boost Converter
Boost Converter

Buck-Boost Converter

In Buck-Boost Converter, the output voltage can be increased or decreased than the input voltage. It works to either boosting or bucking the voltage. The common usage of this converter is to reverse the polarity.

Cuk: This type of converter is similar to the Buck-Boost converter. The difference is its name, named after Slobodan Cuk, the man who created it.

Charge Pump: This converter is used to step the voltage up or down in applications that have low power.

Isolated Converters

These converters have a separation between input and output terminals. They have high isolation voltage properties. They can block the noise and interference. This allows them to produce a cleaner DC source. They are categorised into two types.

Flyback converter

This converter works similar to the buck-boost converter of the non-isolating category. The difference is it uses a transformer to store the energy instead of an inductor.

Flyback converter
Flyback converter

Forward Converter

This converter will use the transformer to send the energy, between the input and output in a single step.

Working of DC Converter

A basic DC-DC converter takes the current and passes it through a switching element, which turns the DC signal into an AC square wave signal. This wave is, then passes through another filter which turns it back into a DC signal of required voltage.

Advantages of DC Converter

  • Battery space can be reduced by reducing or increasing the available input voltage.
  • A device can be driven by bucking or boosting the available voltage. Thus preventing the damage of the device or breakdown.

I hope you have clearly understood the topic- Different  DC to DC voltage conversion methods and their types. If you have any queries on this topic or on the electrical and electronic projects leave the comments below.

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