BASIC KNOWLEDGE An introduction to power converters

Related Vendors

ROHM Semiconductor GmbH

Rogers Corporation

SPACE SE & Co. KG

Power converters are relatively simple circuits that play a fundamental role in enabling electronic devices to function. Here’s an introduction to what power converters are, how they work, and why they’re important.

Power converters are essential and ubiquitous components found in virtually all electronic devices. They were first invented back in 1902 when Peter Cooper Hewitt invented the mercury-arc rectifier, which was used to convert alternating current (AC) into direct current (DC). From the 1920s onwards, research and innovation intensified, eventually leading to the wide range of different power converter solutions that are available today.

What is a power converter?

Power converters are a family of electrical circuits that are designed to convert electrical energy from one level of voltage, current, or frequency to another by using semiconductor electronic switches. They are essential components in electronic and electrical systems, allowing the conversion of electrical power from one form to another to meet specific requirements.

The essential characteristic of power converters is that the switches are operated only in one of two states — either fully ON or fully OFF. This is very different to other types of electrical circuits where the control elements are operated in a near-linear active region. The process of switching devices in a power converter between ON and OFF states is achieved through a process known as modulation, and the development of strategies to implement this in an optimum way has been the subject of research efforts for more than three decades.

RENEWABLE ENERGY

Implementation and Characterization of a 200 kW Full-SiC Isolated DC-DC Converter for Future Medium Voltage PV Plants

How does a power converter work?

Power converters work by altering the characteristics of electrical from one form to another to match the requirements of specific devices or systems. The operation of power converters involves a variety of electronic components and techniques tailored to the type of conversion (AC to DC, DC to AC, DC to DC, or AC to AC).

Although there are different types of power converters, which we’ll explore in more detail later, they’re all made from the same fundamental components:

• Diodes and thyristors, which enable current to flow in one direction.

• Transistors and MOSFETs, which act as switches in inverters and DC-DC converters to enable rapid switching.

• Capacitors and inductors, which store and filter energy to smooth out voltage and current waveforms.

• Microcontrollers, which manage the operation of switches to produce the desired output.

The different power converter types

There are a variety of different power converters available depending on the needs of a given application. These include:

AC-DC converters, also known as rectifiers. These converters are used to convert AC from the power grid into DC, which is required by most electronic devices. They are commonly found in various power supplies, including chargers for batteries and electronic gadgets.

DC-AC converters, also known as inverters. These convert DC power (i.e., that from batteries or solar panels) into AC power, which can be used to operate AC equipment or fed into the power grid. They are essential in renewable energy systems, portable power systems, and for backup power supplies.

DC-DC converters, which are used to change DC power from one voltage level to another. This is crucial in electronics, where different components require different voltage levels. They are widely used in battery-powered devices, laptops, and as part of the power management systems in vehicles. There are different types of DC-DC converters, including:

expert PCIM EUROPE 2021 - BEST PAPER AWARD WINNER

A resonant DC/DC converter with high efficiency and power

• Buck converters, which step down voltage from a higher level to a lower level.

• Boost converters, which step up voltage from a lower level to a higher level.

• Buck-boost, which can either step up or step down the voltage.

• Isolated converters, which include transformers to provide electrical isolation between the input and output, with variations like the Flyback, Forward, and Push-Pull converters.

AC-AC converters, which are used to change one form of AC power (with a certain voltage and frequency) to another. They can adjust output frequency and voltage and are important in applications that require frequency conversion (such as from 60Hz to 50Hz) or in variable frequency drives for controlling the speed of AC motors. Just like there are different types of DC-DC converters, there are different types of AC-AC converters, too:

• Cycloconverters, which convert input power to a lower frequency AC output.

• AC voltage controllers, which control the RMS voltage delivered to the load by adjusting the input waveform.

expert POWER CONVERTER

Compensating a Flyback Converter

Importance and applications of power converters

Power converters play a crucial role in a wide range of applications, primarily due to the diverse nature of electrical power generation and consumption requirements. The need for power converters arises from several fundamental factors:

Compatibility: Different devices and systems require different forms of power (AC or DC) and operate at different voltage and current levels. Power converters ensure compatibility between the power source and the electrical devices by converting the power into the appropriate form and level.

Energy efficiency: Power converters can significantly improve energy efficiency by adjusting the voltage and current to match the load requirements precisely. This minimizes energy loss and improves the overall performance of the electrical system.

Renewables: Renewable energy sources, such as solar panels and wind turbines, often generate DC power or variable AC, which needs to be converted to a stable AC form for use in homes and businesses or for feeding into the power grid. Power converters are essential for integrating renewable energy sources into existing power systems.

Portable Devices: With the proliferation of portable and battery-powered devices, there's a need to convert battery-stored DC power into the required voltage and current levels for these devices. Power converters allow for the efficient operation of laptops, smartphones, electric vehicles, and more.

In terms of applications, power converters are used in a wide variety of areas. The most notable is in consumer electronics, where they’re used in chargers, power supplies, and adapters for electronic gadgets to ensure they receive the correct voltage and current.

They’re also used in electric vehicles, where they manage the charging of batteries and the operation of the vehicle's electric motor, ensuring efficient power flow and usage. Meanwhile, in industrial and commercial applications, converters control machinery, enable speed control of motors, and manage power distribution across complex systems for optimized performance.

(ID:49961812)