# Synthesised Sine wave VS Modified Square Wave inverters

• edsys89
In summary, a modified square wave output is similar to a square wave, but with a delayed transition at the zero point to match the RMS value of a true sine wave. On the other hand, a synthesized sine wave is shaped more like a sine wave but still made of "square blocks" through switching. The RMS value of a synthesized sine wave can be found by multiplying the peak value by 0.707.
edsys89
I am to contrast the difference between modified square wave, and synthesized sine wave inverter outputs.

Am I to understand, that a modified square wave output is like a square wave, but the transtion to current flow in the other direction is delayed some at the zero point. This is to give it the same RMS value as true sine wave ac power.

Furthermore, a synthesised sine wave is shaped more like a sine wave but still made of "square blocks" by switching.

Am I on the right track? Is the RMS value of a synthesised sine wave found by multiplying the peak value by 0.707?

A modified square wave is given by the red curve here:
http://www.pcguide.com/ref/power/ext/ups/funcOutput-c.html

I'm not sure about the details of a synthesized sine wave.

Yes, you are on the right track. The main difference between a modified square wave and a synthesized sine wave inverter is the shape of the output waveform. A modified square wave inverter produces a waveform that is similar to a square wave, but with a delay in the transition from positive to negative voltage, resulting in a smoothed out waveform. This delay helps to achieve a similar RMS value as a true sine wave.

On the other hand, a synthesized sine wave inverter produces a waveform that is closer to a true sine wave, with smoother transitions between positive and negative voltage. This is achieved through the use of pulse width modulation (PWM) techniques, where the voltage is switched on and off rapidly to create a more continuous waveform. The RMS value of a synthesized sine wave can be calculated by multiplying the peak value by 0.707, just like a true sine wave.

In terms of performance, a synthesized sine wave inverter is generally considered to be better than a modified square wave inverter. This is because the synthesized sine wave is closer to the shape of a true sine wave, which is the standard waveform used in most household and industrial appliances. A modified square wave may still work for some devices, but it may cause issues with others that require a smooth and continuous waveform.

In conclusion, the main difference between modified square wave and synthesized sine wave inverters lies in the shape of their output waveforms. While a modified square wave is similar to a square wave with a delayed transition, a synthesized sine wave is closer to a true sine wave. The choice between the two will depend on the specific applications and devices being used.

## What is the difference between a synthesised sine wave inverter and a modified square wave inverter?

A synthesised sine wave inverter produces a smooth, continuous sine wave output that mimics the waveform of electricity from the grid. On the other hand, a modified square wave inverter produces an output that resembles a square wave with stepped edges.

## Which inverter is better for sensitive electronics?

A synthesised sine wave inverter is recommended for sensitive electronics such as laptops, computers, and medical equipment because it produces a clean and stable output that is similar to the electricity from the grid. The abrupt changes in voltage from a modified square wave inverter can cause damage to these devices.

## What is the main advantage of a modified square wave inverter?

The main advantage of a modified square wave inverter is its lower cost compared to a synthesised sine wave inverter. It is also more efficient in converting DC power to AC power, making it a popular choice for basic household appliances.

## Can a modified square wave inverter be used to power all types of appliances?

No, a modified square wave inverter is not suitable for all types of appliances. It is not recommended for sensitive electronics and appliances with motors or transformers, such as refrigerators, air conditioners, and washing machines. These devices require a smooth and stable sine wave for proper functioning.

## Which inverter is more suitable for off-grid or backup power systems?

A synthesised sine wave inverter is more suitable for off-grid or backup power systems because it can provide a stable and reliable output that is similar to the electricity from the grid. This is important for maintaining the functionality of essential electronics and appliances during power outages.

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