What is Power Electronic Converters? Types, Working Principles, and Applications

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Introduction

Power electronic converters play a crucial role in contemporary electrical systems, facilitating the efficient transformation, regulation, and administration of electrical power. These converters are essential across various industries for tasks like regulating voltage levels and transforming AC to DC power. In this comprehensive blog post, we will explore various types of power electronic converters, their operational principles, and practical uses.

Understanding Power Electronic Converters

Power electronic converters are gadgets that transform electric energy from one type to another by changing voltage, current, or frequency to meet the needs of a particular usage. These convertors work by turning on and off semiconductor devices like diodes, transistors, and thyristors to regulate the flow of electric power.

The great strides taken in the industrial applications of power electronics during recent years have demonstrated that this versatile tool can be of great importance in increasing production, efficiency and control. Power Electronic Circuits are also called as power converters. A converter uses a matrix of power semiconductor switches to convert electrical power at high efficiency. The converter system is comprised of switches, reactive components L, C, and transformers. Switches include two terminal devices such as diodes and three terminal devices such as transistors or thyristors. These converters/controllers are generally classified into the following five broad categories:

1. Phase Controlled Rectifiers (AC to DC Converters)

  • These controllers convert fixed ac voltage to a variable dc output voltage. These converters
    take power from one or more ac voltage/current sources of single or multiple phases and delivers to a load. The output variable is a low-ripple dc voltage or dc current.
  • These controller circuits use line voltage for their commutation. Hence they are also called as line commutated or naturally commutated ac to dc converters.These circuits include diode rectifiers and single/three phase controlled circuits.

➤Applications

  1. High voltage dc transmission systems
  2. DC motor drives
  3. Regulated dc power supplies
  4. Static VAR compensator
  5. Battery charger circuits

2. Choppers (DC to DC Converter)

  • A chopper converts fixed dc input voltage to a variable dc output voltage. The dc output voltage may be different in amplitude than the input source voltage. Choppers are designed using semiconductor devices such as power transistors, IGBTs, GTOs, Power MOSFETs and thyristors.
  • Output voltage can be varied steplessly by controlling the duty ratio of the device by low power signals from a control unit. Chopper has either a battery, a solar powered dc voltage source or a line frequency (50-60 Hz) derived dc voltage source.

➤Applications

  1. DC drives
  2. Subway cars
  3. Battery driven vehicles
  4. Electric traction
  5. Switch mode power supplies

3. Inverters (DC to AC Converter)

  • An inverter converts a fixed dc voltage to an ac voltage of variable frequency and of fixed or variable magnitude. A practical inverter has either a battery, a solar powered dc voltage source or a line frequency (50 Hz) derived dc voltage source (often unregulated).
  • Inverters are widely used from very low-power portable electronic systems such as the
    flashlight discharge system in a photography camera to very high power industrial systems.Inverters are designed using semiconductor devices such as power transistors,MOSFETs, IGBTs, GTOs and thyristors.

➤Applications

  1. Uninterruptible power supply (UPS)
  2. Aircraft and space power supplies
  3. Induction and synchronous motor drives
  4. High voltage dc transmission system
  5. Induction heating supplies

4. Cycloconverters (AC to AC Converters)

  • These circuits convert input power at one frequency to output power at a different frequency through one stage conversion. These are designed using thyristors and are controlled by triggering signals derived from a control unit.
  • The output frequency is lower than the source frequency. Output frequency in cycloconverter is a simple fraction such as `1/3`,`1/5` and so on of the source frequency. These are mainly used for slow speed, very high power industrial drives.

➤Applications

  1. AC drives like rotary kilns multi-MW ac motor drives

5. AC Voltage Controllers (AC Regulators)

  • These converters convert fixed ac voltage directly to a variable ac voltage at the same frequency using line commutation.
  • These converters employ a thyristors voltage controller. Stepless control of the output voltage can be obtained by controlling firing angle of converter thyristors by low power signals from a control unit.

➤Applications

  1. Lighting control
  2. Speed control of large fans and pumps
  3. Electronic tap changers

Applications of Power Electronic Converter

Power electronic converters find extensive applications across various industries and technologies:
  1. Power Supplies: DC/DC converters are utilized in power supplies for electronics such as computers and communication gadget to level up the voltage and make the current stable DC.
  2. Renewable Energy Systems: The inverter being the crucial component in solar PV systems as well as wind turbines converts DC power from solar panels or wind generators into AC power that can be directly connected with the grid.
  3. Electric Vehicles (EVs): EV power trains involve power electronic module like DC/DC converters (e.g. charge the battery) and DC/AC inversion (e.g. for motors).
  4. Industrial Motor Drives: VFD (Variable Frequency drives) converters are used to regulate the speed and power of the motor, improving energy efficiency in factory equipment and business processes.
  5. HVDC Transmission: HVDC (high-power direct current) converters increase the efficiency of long-distance power transmission by raising the power over the HVDC lines and yield low losses compared to the transmission of the identical power over the same distance as in the AC transmission.
  6. Grid-Tied Systems: Power electronic converters equipped with the grid connection can include DERs, ESS, and smart grid technologies for the efficient management of power and its integration with the grid of a utility.
  7. Uninterruptible Power Supplies (UPS): Backup power is provided by UPS systems using converters. The converters in UPS systems will automatically kick in to provide power to the critical elements that must remain operational during a blackout.

Conclusion

To sum up, power electronic converters are essential in contemporary electrical systems, allowing for effective energy conversion, control, and management in various applications. With the further development of technology, we can anticipate ongoing advancements in power electronics, leading to increased efficiency, sustainability, and reliability in the energy sector.

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