Types of Three Phase Inverter

Three phase inverters are classified many types according to their features and characteristics . Some of the inverters are:

• Voltage Source Inverter
• Current Source Inverter
• Cascaded Multilevel Inverter
• Hybrid Multilevel Inverter
• Pulse Width Modulated Inverter

Voltage Source Inverter

A voltage source inverter (VSI) is an inverter that converts DC source voltage into an AC output voltage. It is also known as voltage -fed inverter, suitable for situations where the DC source has negligible or low impedance. VSIs are commonly used in Variable-Frequency Drive(VFD) systems to control the speed of 3-phase motors. In this type of inverter DC voltage is very small i.e. negligible and having small impedance .Hence these inverters are also called as voltage fed inverters . These kind of inverters are only used for buck operation and these are used in three phase inverters where the power requirement is high. In VSIs, the DC voltage source is usually provided by battery banks ,consisting of multiple cells connected in series and parallel configurations. This model ensures a reliable and stable DC supply. In some cases, photovoltaic (PV) cells are used as the DC source, harnessing solar energy to power the inverter.

Current Source Inverter

In current source inverter DC current source is converted into AC current at required frequency. In this type of inverters source current is always constant. Hence ,these inverters are called as current fed inverters. These are used only for boost operation and it is not possible to use with more than one motor. The output AC current ‘s frequency is determined by the switching frequencies of various semiconductor devices such as transistors and thyristors. Notably , the defining feature of this inverter is that the input current remains constant. A typical current source inverter setup consists of a DC current source, filters and on an AC load. These inverters are available in both single-phase and three-phase configurations, making them versatile for a wide range of applications. They find use in tasks like starting synchronous motors, power factor correction units, speed control of AC motors, induction heaters, plasma generators, uninterruptible power supplies(UPS),lagging Var compensators and more.

Cascaded Multilevel Inverter

Cascaded Multilevel Inverter is a 3-phase inverter designed for electric utility applications, offering precise control by employing multiple voltage levels to create a stepped waveform. It typically comprises(M-1)/2 H-bridges, each supported by its DC capacitor. These inverters are crucial in renewable energy systems and high-voltage power transmission. By providing enhanced voltage quality and efficient power conversion, they are well- suited for application where stable AC power generation is essential, particularly in the integration of renewable energy sources like solar and wind, as well as in high-voltage transmission systems, ensuring reliable and controlled power delivery over long distances.

Hybrid Multilevel Inverter

The Hybrid Multilevel Inverter is a three-phase inverter specially designed for industrial applications with medium voltage and high power demands. It uniquely combines elements of both current- source and voltage source inverters, offering a versatile solution for complex power requirements. This type of inverter is particularly well-suited for high power applications, including electric vehicle charging stations. Its ability to efficiently handle medium voltage and high-power scenarios makes it a valuable component in modern industries where reliable and controlled power conversion is essential. The hybrid multilevel inverter plays a pivotal role in enhancing power infrastructure, enabling the efficient charging of electric vehicles and meeting the demands of high-power industrial operations.

Pulse Width Modulated Inverter

A Pulse with Modulated (PWM) is a specialized inverter that consists of pulse-width modulation technique to precisely control the output frequency and voltage. This inverter operates by rapidly switching Insulated Gate Bipolar Transistors(IGBTs) on and off, enabling it to generate nearly ideal sinusoidal voltage with minimal harmonic distortion. The key advantage of PWM inverters is their ability to produce high-quality AC power that closely resembles a pure sinusoidal waveform, making them crucial in applications where clean and stable electricity is essential. Includes renewable energy systems such as solar and wind power, Where PWM inverters efficiently convert DC power from solar panels or wind turbines into grid-ready Ac power with minimal distortion. Moreover ,PWM inverters find extensive use in motors drives , providing precise control over the speed and torque of electric motors. Their capability to deliver clean and accurately regulated AC power makes them indispensable in various industrial and commercial applications, ensuring efficient and reliable operation of equipment and machinery.

An inverter is a fundamental electrical device designed primarily for the conversion of direct current into alternating current . This versatile device , also known as a variable frequency drive , plays a vital role in a wide range of applications , including variable frequency drives and high power scenarios such as high voltage direct current (HVDC) power transmission. Its primary function is to control the torque and speed of electrical motors , making a vital role in many industrial and commercial settings. The versatility of inverters extends to their role in HVDC power transmission, where they are crucial in converting the DC power generated in power plants or offshore wind farms into AC power suitable for long transmission .

In this context , inverters help minimize energy losses and maximize the efficiency of electricity distribution over extensive distances. Here we will discuss about circuit design and working of inverter , types of inverters , advantages , limitations and applications of inverters .