One of the most important conflicts of the 19th century was fought for the sort of electricity that powers our structures, not over territory or other resources.
Thomas Edison (1847–1931), an American electrical pioneer, made an effort to show that direct current (DC) was a superior method of supplying electrical power than alternating current (AC), which was supported by his arch-rival Nikola Tesla (1856–1943).
Edison used a variety of crafty tactics, including as electrocuting an elephant and (quite cunningly) advocating the use of AC in the electric chair to carry out the death sentence, to try to persuade people that AC was too hazardous.
However, Tesla’s technique ultimately prevailed, and since then the globe has mostly been powered by AC.
The main issue is that although many of our gadgets are designed to operate on AC, DC is often produced by small-scale power sources.
Accordingly, a device known as an inverter is required if you wish to power anything like an AC-powered equipment in a mobile home using a DC automobile battery.
Let’s examine these devices more closely and see how they operate.
Table of Contents
What Distinguishes DC From AC Electricity?
Usually, direct current is what science professors refer to when they describe the fundamental concept of electricity to us as a flow of electrons (DC).
We discover that the electrons behave much like a line of marching ants, carrying electrical energy packets as ants carry leaves.
That serves as a suitable analogy for an object like a simple flashlight, which consists of a circuit (an uninterrupted electrical loop) connecting a battery, a lamp, and a switch.
Electrical energy is systematically transferred from the battery to the lamp until the battery is completely discharged.
Electricity operates in larger home equipment in a different manner.
Alternating current (AC), or energy that alternates direction around 50–60 times per second (50–60 Hz), is the basis of the power source that emerges from the socket in your wall.
When AC continuously changes its mind about where it’s going, it might be challenging to grasp how it provides energy! How do the electrons from your wall outlet ever reach the lamp on your table to turn it on if they have to go back and forth after traveling a few millimeters down the cable?
Actually, the answer is fairly straightforward.
Consider the wires that connect the bulb to the wall being loaded with electrons.
When the switch is turned on, the whole cable’s electron population vibrates quickly back and forth in the filament of the lamp, converting electrical energy into heat and causing the light to shine.
In AC, electrons “run on the spot” rather of necessarily running in a circle to carry energy.
What are the distinctions between DC and AC electricity? Let’s say you need to vacuum a space.
Alternating current is similar to moving back and forth on the spot whereas direct current is like moving from one side to the other in a straight line.
Both do the same task, just significantly differently!
Describe the Inverter.
The majority of the appliances we have in our homes are made expressly to operate off AC power, which is one of Tesla’s contributions—along with that of his business partner George Westinghouse, the head of the Westinghouse Electrical Company.
An additional piece of equipment called a rectifier, which is commonly constructed from electrical components called diodes, is required to convert from AC to DC for appliances that need DC but must be powered by AC outlets.
An inverter performs the opposite function, and the basic principles behind its operation are relatively simple.
Consider a battery in a flashlight with the switch closed, causing DC to travel through the circuit in one direction only, much like a racecar around a track.
What happens if you flip it over after removing the battery? It will very probably still power the flashlight if it fits the other way, and you won’t notice any change in the amount of light you get—but the electric current will really be going the other way.
Imagine you possessed hands that moved at the speed of light and were quick enough to reverse the batteries 50–60 times per second.
The battery’s DC electricity would then be converted into AC at a frequency of 50–60 hertz by you, acting as a kind of mechanical inverter.
Typical electrical inverter in picture.
Made by Xantrex/Trace Engineering, this one.
Photo courtesy of US Department of Energy/NREL by Warren Gretz.
Although some are mechanical, the inverters you purchase at electrical shops don’t always operate in this manner.
Instead, they employ electromagnetic switches that rapidly flicker on and off to reverse the direction of the current.
Such inverters often create a square-wave output, in which the current is either flowing in one direction or the other or is rapidly switching between the two states:
Some types of electrical equipment are very vulnerable to these kinds of abrupt power changes.
In a sine-wave pattern, the current gradually switches in conventional AC power from one direction to the other as follows:
This kind of gradually fluctuating AC output from a DC input may be created using electronic inverters.
Instead of the basic inverter’s sudden, on/off-switching square wave output, they employ electrical components called inductors and capacitors to make the output current increase and decrease more gradually.
The output power must always be less than the input power because an inverter and transformer cannot output more power than they consume, and some energy is bound to be lost as heat as electricity flows through the various electrical and electronic components.
Inverters can also be used with transformers to change a specific DC input voltage into a completely different AC output voltage (either higher or lower).
Although in reality an inverter’s efficiency is often above 90%, fundamental physics informs us that some energy—however small—is constantly being lost somewhere.
What Is The Process Of An Inverter?
Inverters have just been briefly discussed; now let’s go over it once more in more depth.
Think of yourself as a DC battery that has been asked to generate AC instead after receiving a tap on the shoulder.
What method would you use? What about adding a simple switch to your output lead if all the current you generate goes out in one direction? Pulses of direct current would be produced by quickly turning your current on and off; this would accomplish at least half the task.
You would need a switch that could totally reverse the current at a rate of 50–60 times per second in order to provide appropriate AC.
Consider yourself a human battery switching contacts more than 3000 times each minute.
You’d need some fancy fingerwork for that.
An old-school mechanical inverter is essentially nothing more than a switching device attached to an electrical transformer.
If you’ve read our article on transformers, you know that they use two wire coils (referred to as the primary and secondary) coiled around a common iron core to shift low-voltage AC to high-voltage AC, or vice versa.
In a mechanical inverter, the incoming direct current is switched back and forth in the primary by an electric motor or other automated switching mechanism, simply by reversing the contacts, and this results in alternating current in the secondary—so it’s not all that dissimilar from the hypothetical inverter I sketched out above.
Similar to the one in an electric doorbell, the switching mechanism operates similarly.
When the electricity is turned on, the switch becomes magnetized, drawing it open and temporarily turning it off.
A spring moves the switch back into place, turning it on once again and repeating the process.
An electromechanical inverter’s fundamental design, shown in animation.
A spinning plate (red and blue) with crisscross connections feeds DC into the primary winding (pink zigzag wires on the left side) of a toroidal transformer (brown donut).
The connections to the main winding are frequently switched as the plate spins, providing AC instead of DC as the transformer’s input.
This step-up transformer increases a low AC input voltage into a high AC output by having more windings in the secondary (yellow zig-zag, right side) than the primary.
The AC output frequency is controlled by the disk’s rotational speed.
This is only an example; most inverters don’t operate in this manner.
This configuration of an inverter would result in a highly shaky square wave output.
Various Inverter Types
A DC current results in highly sudden variations of current if you merely turn it on and off or flip it back and forth such that its direction continues changing.
The current will go all in one way, all in the other direction, and then back again.
You will obtain a square wave if you plot the current (or voltage) versus time.
Although technically an alternating current, energy that fluctuates in that way differs greatly from the alternating current delivered to our houses, which varies in a much smoother undulating sine wave.
Heavy appliances in our houses that consume raw electricity, such as electric heaters, incandescent lights, kettles, or refrigerators, typically don’t care much about the form of the wave they get since all they want is energy, and plenty of it.
Therefore, square waves don’t really affect them.
On the other hand, electronic equipment are considerably pickier and favor the sine wave’s smoother input.
Picture of Nikola Tesla Thomas Edison is still regarded as the inventor of electric power, despite the fact that he prevailed in the battle of the currents.
By Sarong, around 1906; image courtesy of US Library of Congress.
This explains why there are two types of inverters: modified/quasi sine wave inverters and true/pure sine wave inverters (commonly abbreviated to PSW) (shortened to MSW).
True inverters, as their name implies, convert direct current into an alternating current with smoothly fluctuating frequency that is extremely comparable to the sort of real sine wave often provided to our houses using toroidal (donut-shaped) transformers and electronic circuits.
They may be used to power any kind of AC equipment, such as TVs, laptops, video games, radios, and stereos, from a DC supply.
Modified sine wave inverters, on the other hand, produce a kind of “rounded-off” square wave (a much rougher approximation to a sine wave) using relatively inexpensive electronics (thyristors, diodes, and other simple components), and while they’re fine for delivering power to substantial electric appliances, they can and do cause problems with delicate electronics (or anything with an electronic or microprocessor controller), so, generally speaking, that means they’re unsuitable for t Additionally, if you consider it, the appliance is receiving more power from their rounded-off square waves than from a pure sine wave since a square has a larger surface area than a curve.
As a result, MSW inverters are less effective and run the slight risk of overheating due to the lost power that is released as heat.
On the plus side, they are often far less expensive than real inverters.
Illustration: A modified sine wave (MSW, green) is more akin to a sine wave (blue) than a square wave (orange), but both still include abrupt, jarring changes in current.
A modified sine wave becomes closer to the idealized version of a real sine wave as there are more steps in it.
Some inverters, known as utility-interactive inverters or grid-tied inverters, are specifically made to be connected to the grid at all times; typically, they’re used to send electricity from something like a solar panel back to the grid at exactly the right voltage and frequency.
While many inverters operate as standalone units with battery storage that are completely independent from the grid, others (known as grid-tied inverters or utility-interactive inverters) work as standalone units with battery storage that are That’s OK if producing your own energy is your major goal.
It’s not very helpful if you want to occasionally be off the grid or if you need a backup power source in case of an outage because if your connection to the grid goes down and you’re not producing any electricity of your own (for example, it’s nighttime and your solar panels are off), the inverter goes down too, and you’re left without power—just as helpless as you would be whether you were producing your own power or not.
Due to this, some individuals utilize bimodal or birectional inverters, which may operate either independently or in conjunction with a grid (though not both at the same time).
They often cost more and are more costly since they contain more parts and sections.
How Do Inverters Work?
Inverters may be rather large and heavy, particularly if they include integrated battery packs that allow them to function independently.
They produce a lot of heat as well, which is why they often feature cooling fans in addition to big metal fins that serve as heat sinks.
From our top image, you can see that normal ones are around the size of a car battery or vehicle battery charger; bigger units resemble a bank of car batteries stacked vertically.
The tiniest inverters are smaller, more portable units around the size of a car radio that you can plug into your cigarette lighter socket to generate AC for charging laptops or telephones.
Photo: A single photovolatic solar panel’s DC output is normally converted into AC by tiny, compact inverters called microinverters, which may then be delivered directly into the electrical grid.
To put it another way, every panel has a separate microinverter.
The National Renewable Energy Laboratory is testing six Enphase IQ 6 microinverters in this image (NREL).
Because they are linked to the Internet, you can check on their performance and see how it evolves over time using a web browser.
With permission from NREL, a photo by Dennis Schroeder
Inverters vary in the amount of electricity they generate, just as appliances vary in how much power they need.
You’ll often need an inverter rated around a quarter higher than the maximum power of the appliance you wish to drive in order to be safe.
This takes into account the fact that certain devices (such refrigerators and freezers or fluorescent lights) use their peak power when they are initially turned on.
Although inverters may function at peak power for brief periods of time, it’s crucial to keep in mind that they weren’t originally built to do so.
An Uninterruptible Power Supply Is What?
Emergency power supplies, also known as uninterruptible power supplies or uninterruptible power sources, are a fairly popular use for inverters (both going by the acronym UPS).
You could have a UPS as a backup if your home’s power goes out during a blackout, but how does it operate?
Typical UPSs use rechargeable batteries to store energy in electrical form (some UPS systems store energy in mechanical form using a high-speed flywheel, spun to high speed by an electric motor).
When the electricity is operating properly, a transformer and rectifier circuit provide DC from the AC power source, which is used to trickle charge the batteries.
Charged batteries that can create direct current but need alternating current to power your house can come in handy if the power goes out.
Therefore, the batteries pump DC via an inverter to create AC while the UPS is delivering power.
To provide a robust power supply that can withstand spikes, surges, over-voltage, under-voltage, or a full loss of power, a UPS is sometimes paired with a surge protector and voltage optimization equipment.