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What Is A Pure Sine Wave Inverter?

If you’re trying to understand the workings of a pure sinewave inverter, then you might be considering installing a solar system that includes batteries for your RV or your home.
If you’ve done your research already, you may have read about the two main inverter technology: modified sine waves and pure sine waves.

A pure sine wave converter can cost up to twice as much as a modified sinewave inverter. So, what are they good for? You might then wonder what a pure sinewave converter is.

A pure sine wave converter will convert direct current (DC), to alternating currents (AC). This can be used to supply high-quality electricity to all types of appliances (similar to utility standard voltage, frequency 50/60hz, frequency 230V)

Pure sine wave converters can also be used as transformers. They can raise the input DC voltage from 12V to a much higher AC voltage like 230V.

We will then discuss the operation of pure sine wave converters in detail. A brief comparison between the main inverter technologies will then be made. Then, you’ll be shown why your electrical system should use the most recent pure sine wave inverter tech.

What is a pure sine wave inverter?

Let’s first understand what a pure sine wave converter is and why we need one for our electrical system.

You might be familiar with the two types of current.

AC, Alternating Current
DC, Direct Current

What’s the difference between AC and DC?

Brief History
Two prominent scientists attempted to make their technology a standard when the world began its electric revolution (end 19th century, start of 20th).

Nikola Tesla was advocating for AC electricity, while Thomas Edison strongly supported DC electricity. As AC electricity is now the main source of power for most household appliances, and electric motors, it was clear that Tesla won.

However, DC continues to be used and is gaining popularity with the advancement of solar energy. In fact, both solar panels and batteries can produce DC power.

After some background, you might still be wondering about the main differences between AC or DC.

First of all, electricity can be described as a flow electrons.

DC electrons flow one way. They move from the negative electrode towards the positive electrode. You can visualize it as a continuous and straight current over time.

AC is the opposite. Electrons can flow alternately in either direction in a periodic circle. It can be described as a sine-wave current in time.

AC and DC are very different. Therefore, it is important to avoid connecting AC appliances to DC sources. Your AC appliance will be irreparably damaged.
How can we convert DC to AC?

Electrical engineers developed a device that converts DC from AC to AC in order to overcome the compatibility issue between AC and DC. This is known as the “inverter”.

An inverter that is pure sine wave will therefore:

Produce alternating current from a source of direct current (DC).
Provide high-quality electric current that is comparable to utility standards (voltage at 230V, frequency at 50/60hz).

Pure sine wave converters can also be called transformers. They boost the input DC voltage up to a much higher AC voltage (e.g., 12V – 230V).

Let’s find out how it works now that we know the basics of a pure sine wave converter.
How does a Pure Sine Wave Inverter work?

We previously saw that pure sinewave inverters first convert DC to AC, then increase the input voltage (12V-24V, 48V ), and finally reach an output voltage (transformer) of 230V. This is what all our household appliances can use.

Let’s look at these two steps of a pure sinewave converter.
From direct current (DC), to pure sine-wave alternating current (AC)

Here is a simplified working principle that demonstrates how pure sinewave inverters operate.

It’s difficult to convert a straightline (DC) into an AC wave in which the current flows continuously in both directions.

Let’s start by making a simple change.

The square-shaped current can be generated by switching the DC current on and off periodically. It alternates between zero (switch Off), and maximum value (switch ON).

Ok, now you have a periodic current. However, it’s not flowing in both direction and is far from a sinewaveform.

A type of automatic switch is required to alternately reverse the current flow by flipping the contact.

This can be illustrated by a rotating disk connected to each other. Frequency of the alternating current is determined by the speed of rotation.

Now you have a flowing current in both directions. But it still looks like a square. You will need to use a few more electronic circuits in order to make the square look like a sine wave.

How can pure sine wave inverters increase voltage?

The second step involves increasing the voltage of pure sine wave current. DC can be either 12V, 24V and 48V. AC is 230V.

The transformer can do the job. It is an electromagnetic device that is made of an iron core with two copper wire coils, the primary and second coils. The primary coil receives the low voltage voltage current, and the secondary coil emits the high voltage.

The coils are not in direct contact at the end and the current is transferred to the other via electromagnetic induction.

The output voltage can be controlled by the wire density of the coils. A step-up transformer increases the voltage by increasing the wiring density of the secondary coil.

Transformers are all around us. Your cell phone and laptop chargers, for instance, are step-down transformers.