DC/DC Converters: Converter Topology

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DC/DC Converters: Converter Topology

Posted Date: 2024-01-19

Converter topology

DC/DC converters are a key aspect of research in power electronics and energy drives as they are widely used in a variety of industrial applications. DC/DC conversion technology was established in the 1920s [1]. Since then, DC/DC conversion technology has advanced significantly. They are also undergoing significant changes due to two major industry trends: low voltage and high power density. This has resulted in a range where the output of DC/DC converters far exceeds that of AC/DC converters.

In its simplest form, a DC/DC converter is a voltage divider, such as a rheostat or potentiometer. However, it can only transmit an output voltage lower than the input voltage and has poor conversion efficiency. Some basic voltage divider circuits are shown in Figure 1.

Figure 1. Basic voltage divider circuit. Image property of EETech

The next step in the evolution of DC/DC converters is the multi-quadrant chopper.

The development of communication technology has promoted the rapid development of DC/DC conversion technology. At a high level, DC/DC converters have been divided into several generations of DC/DC conversion topologies based on their evolution. They are classified as belonging to different converter families. According to some probably incomplete statistics, more than 500 DC/DC converter prototypes have been developed in the past 6 years.

Classification of DC/DC converters

Classic or traditional converters are classified as generation converters. They typically operate in single-quadrant mode and operate in the low power range. These include basic converters such as buck, boost, and buck-boost converters, as well as some transformer-type converters.

Second-generation converters include multi-quadrant DC/DC converters that operate in two- or four-quadrant operating modes. They operate in the medium output power range and can be divided into two broad categories - topologies derived from generation converter based topologies and transformer-based topologies.

The third generation converter is formed based on the switching component converter and is implemented using an inductor or a capacitor, hence it is called a switched inductor or switched capacitor circuit. They operate in two- or four-quadrant, have a high output power range, and have the advantages of high power density and conversion efficiency.

The fourth-generation converter mainly consists of soft-switching converters such as zero-current switching (ZCS) and zero-voltage switching (ZVS) converters. They can be divided into resonant switching converters, load resonant converters, resonant DC link converters and high frequency link integrating half-cycle converters. Most attention has been focused solely on resonant switching conversion methods.

Fifth-generation converters include synchronous rectifier (SR) converters, which are critical to the development of computing technology. Generally speaking, power supplies with low output voltage and high current are widely used in communications, industrial applications, and computer equipment.

The sixth generation converter consists of multiple energy storage element resonance (MER) converters. These, in turn, are classified according to resonant energy storage elements.

Figure 2 shows an overview of the DC/DC converter family.

How DC/DC converters work

For buck, boost, and buck-boost converters, switches and diodes alternately turn on and off. They usually operate in continuous conduction mode, and the inductor current is continuous. Some buck-boost converters such as SEPIC and Cuk are built on traditional topologies while providing additional benefits such as reduced current ripple at the terminals [2].There are other transformer based topologies such as forward converter, flyback converter, push-pull converter, bridge converter and Zeta converter [3]. These can be analyzed similarly to basic converters and the basic electrical principles of resonance and mutual inductance using circuit analysis concepts such as Kirchhoff's laws.

#DCDC #Converters #Converter #Topology