Power Electronics

Power electronics is the technology for efficient conversion, control, and management of electric power and to control the flow of electrical energy. Power electronics are used in everything from laptop chargers to inverters driving electric vehicles and renewable energy systems.

Power electronics manage the flow of electricity, maximizing performance and minimizing waste. Power Electronics runs the devices efficiently with the control and conversion of electric power.

Power electronics can be defined as the application of solid-state electronics for the control and conversion of electrical power. Power electronics is a technology for the conversion, regulation, and management of electric power. It deals with the processing of high currents and voltages that help in the delivery of power to many areas for use.

Power electronics use electronic devices and circuits to efficiently and precisely control the flow of electrical energy for various applications. Power electronics play an important role in transforming and regulating the voltage, current, and frequency in different electrical applications.

Power electronics have a wide range of applications in energy conversion and transmission of motor control, in renewable energy systems, and in electric vehicles.

The main blocks of a power electronics system are:

• Source of Electrical Power
• Power electronic converter circuit
• Electrical Load
• Sensor, Sensing Unit, or Feedback Circuit
• Control Unit or Controller

Source of Electrical Power

Mainly, there are two types of electrical energy sources. They are

• AC
• DC

Power electronic converter circuit

• Power electronic converter circuits convert the input power from the source to a suitable form as required by the load.
• For example, it we have a DC source and need to supply an induction motor, then it is necessary to convert DC to AC, which is achieved using power electronic converter circuits.
• It works as a converter.
• During transient operation, it retrieves the source and motor current in cases of excessive current (overload).

Electrical Load

• The load can be a motor, battery, etc. Usually, loads are specified by their power rating and the type of source required. The ratings of the load largely determine the ratings of the power electronic converter circuit.

Sensor, Sensing Unit, or Feedback Circuit

• The sensing and feedback circuits monitor the load conditions. For example, speed and output current are sensed in the case of motor loads.
• The sensing unit helps in sensing certain drive parameters, like current or voltage, may be required for protection or for closed loop operation.

Control Unit or Controller

• The control unit consists of the drive circuits of the power electronic converter circuit.
• The drives of the switches are adjusted according to feedback and reference values.
• It consists of control circuits that are operated as power modulators as desired.

A power electronic system consists of an electrical energy source, a power electronic converter circuit, an electrical load, a sensor and control circuit. The converter and controller are two major components in working.

The power converters change one form of electric power into another with the use of a power semiconductor device. While power controllers are the ones that are responsible for producing control signals relative to turning on or off the switching devices present within the circuit, this is divided into a variety of applications:

• Power Generation
• Power Transmission
• Power Control
• Power Distribution

The complete operation of the system will provide the desired signal at a particular frequency, as shown in the block diagram given below, and it will include several steps:

Step 1

In power electronic systems, there can be an AC or DC source of electric power. The DC electric power source can be a DC generator, battery, etc., while the AC electric power source can be an alternator or induction generator. With the use of a controller, a signal of controlled power reaches the load end from the source via a converter.

Step 2

Next, the converter provides ac or dc electric power according to the load with variable voltage and frequency. The electric power at the output is dependent on the load. When the load is DC motor, the converter provides the output as an adjustable DC voltage.

Step 3

The parameters on which the load is measured, like voltage, current, etc., act as the input signal for the controller unit. These are known as feedback signals or controller input signals. Along with the feedback signal, the controller is also provided with the reference input signal.

The control signal generated by the controller is an outcome of the comparison made between the feedback signal and the reference input signal. This control signal regulates the turning on and off of the switching devices of the power converter.

Final Output

In this way, with proper control, the desired output is achieved at the load.

Power electronic circuits are mainly classified into four types:

• AC-to-DC Converter (Rectifiers)
• DC-to-DC Converters (Choppers)
• AC-to-AC Converters (Cycloconverters)
• DC-to-AC Converters (Inverters)

AC-to-DC Converter (Rectifiers)

These are also called as AC-to-DC converters or controlled rectifiers. The line-commutated converters (controlled rectifiers) are used to convert a fixed voltage, fixed frequency AC power supply to a variable-voltage DC output. Rectifiers are power electronic circuits that are used to convert 1 or 3-phase AC input to DC output.

The input is a single phase or three phase AC supply normally available from the mains. The output is controlled by DC voltage and current.

DC to DC Converters (Choppers)

Choppers are power circuits that obtain power from a fixed-voltage DC supply and convert it into a variable DC Voltage. Choppers are power electronic circuits that convert fixed DC input voltage to fixed or variable-voltage DC supply.

Choppers are popularly used in DC drive applications, where the speed of the motor can be controlled in forward and reverse directions. Choppers take input from a fixed DC source or from the output of an uncontrolled rectifier.

AC to AC Converters (Cycloconverters)

AC voltage controllers convert the constant frequency, fixed voltage AC supply into a variable-voltage AC supply at the same frequency using line computation. Cycloconverters are power electronic converter circuits used to convert a fixed AC input voltage to a fixed or variable (voltage or frequency) AC output. The output frequency is lower than the input frequency.

DC to AC Converters (Inverters)

Inverters are power electronic converter circuits used to convert fixed DC input to fixed or variable AC output. The inverters employ the force commutation method to turn off the thyristors. The input for the inverters is usually obtained from batteries. Inverters are used for speed control in induction motors.

A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics, for example, in a switch-mode power supply. Such a device is also called a power device or, when used in integrated circuits.

Power devices operate at lower switching speeds, whereas signal devices operate at higher switching speeds. Power semiconductor devices are extensively used in power electronic circuits.

These power semiconductor devices are divided into three types:

• Diodes
• Thyristors
• Transistors

Power Diode

Diodes play a significant role in power electronics circuits. These are uncontrolled rectifying devices. It acts as a switch to perform various functions, such as switching in rectifiers, change reversal of capacitors, energy transfer between components, voltage isolation, and energy feedback from the load to the power source.

Thyristors

Thyristors are extensively used in power electronic circuits. They are operated as bistable switches, operating from state to conducting state. The members of the Thyristors family are SCR, LASCR, RCT, GTO, SITH, and MCT.

Transistors

The power transistors have controlled turn-on and turn-off characteristics. The switching speed of power transistors is much higher than that of thyristors, and they are extensively used in dc-dc and dc-ac converters. The power transistors can be classified as BJTs, MOSFETs, SITs, and IGBTs.

Some of the applications of power electronics are listed below.

• Electric Transportation: Power electronics have countless applications in real life. It is used in electric vehicles for the charging and discharging of the battery and to regulate the continuous power flow in the vehicle.
• Industrial drives: Power electronics that are used in industries are cement mills, rolling mills, windmills, elevators; they are also used to improve efficiency and control the speed and torque of the motor.
• Energy storage: For stable power conversion, energy storage in done in batteries and in other forms.
• Power distribution and transmission: The power electronics that are used in utility systems are smart grids, FACTS, HDVC transmission, improving system efficiency, and preventing power losses.
• Renewable energy: The power electronics that are used in renewable energy are solar systems, turbines to convert the power into AC power, which can be transmitted to the power grid.

Some benefits of the power electronics are listed below.

• Energy efficiency: Low efficiency due to low loss in the power semiconductor devices
• Reliability: High reliability of the power electronic converter system.
• Durability: Long life and less maintenance due to the absence of any moving system.
• Prompting: Fast dynamic response of a power electronic system as compared to an electro-mechanical system
• High speed switching: Power can flow easily and efficiently with high-speed switching.

Some of the disadvantages of power electronics are given below.

• Power electronics converters have a low overload capacity.
• Power electronics converter circuits have a tendency to generate harmonics in the supply system as well as in the load.
• It has low power factor operation.
• Regulation of power is difficult in a power electronics converter.

• Power electronics systems are used in a wide range of applications and have the potential to impact any area of ​​global industrial and social activity. From cellphones to pacemakers, and utilities to automobiles, power electronics, and the engineering behind those electronics are very influential in people’s daily lives.
• From power generation to transportation and communication technologies to average kitchen appliances, power electronics and the engineers behind these electronic devices are everywhere.

The future of power electronics is expected to be driven by:

• In the growth of renewable energy.
• In the development of smart grid technology.
• In the growth of the electric vehicle market.
• In the trend toward miniaturization and integration.
• Energy storage systems, such as batteries and supercapacitors, will play an increasingly important role in the future of power electronics.
• The integration of artificial intelligence and machine learning will also play a significant role.

In this article, we have seen what power electronics, the different types of power electronic circuits, their benefits and the future range of applications of power electronics in every field. The main purpose of power electronics is the process, convert, manage and control electric power by providing sufficient voltage and current so that it will be suitable for various consumer applications. Power electronics are used to transform how we generate, distribute, and utilize electricity.

What is the Basic Working of Power Electronics?

The variable input power is received from the source, then the controller processes it to generate output that is then provided to sensors that give load parameters feedback, and the controller regulates feedback on switches.

What do you mean by power electronics?

Power electronics can be defined as the technology that enables the efficient conversion, control, and conditioning of electric power by static means from its available input form into the required electrical output form.

What are the main components of power electronics systems?

Power electronics systems consist of power semiconductor devices, passive components, control circuits and cooling systems.

What is the application of power electronics?

Power electronics are used in different fields like transportation, industries, aerospace, defense, etc.