top of page

Differences between a 2 level inverter and a 3 level inverter

Updated: Oct 3, 2023


In power electronics devices, an inverter is the one that converts DC voltage into AC voltage of a desired frequency and waveform. Inverters are widely used in various applications such as renewable energy systems, motor drives, and UPS systems. There are two common types of inverters based on their output voltage levels: 2-level and 3-level inverters. In this blog let’s discuss the major differences between these two types of inverters.


Basics of Inverters

Before delving into the differences between 2-level and 3-level inverters, it is important to understand how inverters work. An inverter converts DC power into AC power, which is suitable for use in homes and businesses. The process of converting DC to AC involves switching the DC voltage on and off at a high frequency to create a sine wave. The sine wave produced by the inverter must be as close as possible to the AC power grid's sine wave to ensure efficient and reliable operation. The inverter's output voltage, frequency, and waveform must be carefully controlled to match the AC grid's specifications. There are various kinds of inverters in the market, now by understanding the efficiency and cost factor most people are switching for solar power inverter.


Two-Level Inverter

A 2-level inverter is the simplest type of inverter. It consists of two switches that are connected to a DC voltage source and an AC load. The switches can be either bipolar junction transistors (BJTs) or metal-oxide-semiconductor field-effect transistors (MOSFETs). When one switch is closed, current flows through the load, and the output voltage is positive. When the other switch is closed, current flows in the opposite direction, and the output voltage is negative.


By switching the two switches on and off at a high frequency, the 2-level inverter can produce an AC voltage with a frequency and waveform that matches the AC grid. The main advantage of a 2-level inverter is its simplicity. It has only two switches, which means that it is easy to design and manufacture. It is also relatively inexpensive compared to other types of inverters.


Three-Level Inverter

A 3-level inverter is a more advanced type of inverter that overcomes some of the limitations of the 2-level inverter. It consists of three switches, which can be either BJTs or MOSFETs, and a DC voltage source and an AC load. The three switches are arranged in a configuration known as a "H-bridge." The H-bridge allows the inverter to produce three voltage levels: positive, zero, and negative.


By switching the three switches on and off at a high frequency, the 3-level inverter can produce an AC voltage with a frequency and waveform that matches the AC grid. The main advantage of a 3-level inverter is its ability to produce a sine wave output voltage that closely matches the AC grid's waveform. The three voltage levels produced by the inverter allow it to produce a smoother, more sinusoidal output voltage, which is ideal for sensitive electrical loads such as motors and audio equipment. Another advantage of a 3-level inverter is its ability to produce higher voltage levels. By using a technique known as pulse width modulation (PWM), the 3-level inverter can produce an output voltage that is twice the DC voltage source's voltage.


Differences between a 2 level inverter and a 3 level inverter


Output Voltage Levels: A 2-level inverter generates an output voltage waveform that switches between two voltage levels, typically +Vdc and -Vdc, whereas a 3-level inverter generates an output waveform that switches between three voltage levels, typically +Vdc, 0V, and -Vdc.


Harmonic Distortion: Due to its limited output voltage levels, a 2-level inverter produces higher harmonic distortion compared to a 3-level inverter. A 3-level inverter, with its additional voltage level, produces lower harmonic distortion in the output waveform, resulting in better performance and efficiency.


Switching Frequency: A 2-level inverter requires a higher switching frequency than a 3-level inverter to produce the same output waveform. This is because a 2-level inverter generates a staircase-like output waveform, which requires more switching events to produce the same waveform as a 3-level inverter.


Topology: 2 level inverters have a simpler topology than 3 level inverters. 3 level inverters have more complex circuits with additional switching devices and capacitors.


Output voltage waveform: 2 level inverters produce a square wave output voltage waveform, while 3 level inverters produce a more sinusoidal output voltage waveform with lower harmonic distortion.


Efficiency: 3 level inverters are generally more efficient than 2 level inverters due to their lower harmonic distortion and more sinusoidal output voltage waveform.


Cost: 3 level inverters are generally more expensive than 2 level inverters due to their more complex topology and additional components.


Applications: 2 level inverters are commonly used in low-power applications such as home appliances and lighting systems, while 3 level inverters are suitable for high-power applications such as electric vehicles, industrial motors, and renewable energy systems.


Wrapping Up:

In conclusion, both 2 level and 3 level inverters have their own advantages and disadvantages. 2 level inverters are simple and cost-effective, but they produce high harmonic distortion in the output voltage. 3 level inverters are more complex and expensive, but they produce a more sinusoidal output voltage waveform with lower harmonic distortion and are suitable for high-power applications. If you are looking for a better option, you can also try out any smart solar inverter available in the market. Overall, the choice between a 2-level inverter and a 3-level inverter depends on the specific application and its requirements for output waveform quality, efficiency, and cost.


255 views0 comments

Comments


bottom of page