What is inverter generator? And How It is Different from Conventional Generator?

Many times you may have heard that the inverter generators are fuel-efficient and quieter than conventional generators. Have you wondered why is that so?
Well, today we are going to answer all your queries regarding inverter generators, so keep reading.
But before this you need to understand how alternator works. The alternator is almost the same as generator however there is one big difference. In alternator, the rotor is excited with DC current and thus strong magnetic field is produced by rotor. And when the rotor rotates, the stator cuts these magnetic field and hence the electricity is produced which is collected through the stator.
But in case of generator, armature winding rotates in a fixed magnetic field and the stator produces this magnetic field with the help of excitation winding. The electricity is collected through the rotor with the help of carbon brushes and they wear out quickly so you need to replace them frequently.

Difference between inverter generator and conventional generator

The conventional generator or non-inverter generator produces directly AC current, whereas the inverter generator produces AC current, then converts it to DC current and then again converts it back to AC current, and it has many advantages which we will discuss later. An inverter generator is also fuel-efficient; let’s understand this by this equation.

This is the equation of rotor speed of the generator, and all the generators, including inverter generator, alternator, and the conventional generator, produce the power based on this equation.
Countries like America and Canada use the 60Hz frequency, so here f=60 and P is number poles of any particular generator. Almost all the generators (except for generators used in Hydropower) have two pole arrangement.
Now, as you know, the frequency of the current must be 60Hz, and if the frequency fluctuates even the slightest, let’s say 58Hz or 61Hz, then it may damage your appliances.
If we do the simple math, then to get f=60, the value of n must be 3600 RPM (Rotations per Minute). This means that the rotor of the generator must run at a constant 3600 RPM no matter what. And if this speed increases or decreases, then it may change the frequency of output current.
So now, you know that conventional generator must run at 3600 RPM constantly no matter what amount of power is asked of it.
Let’s understand it by this example. Suppose you have a generator that can supply 1000 watts of continuous power (not peak power), and you want to run a 100-watt bulb. So it will burn some fuel, right? Now let’s say you want to run an electronic device of 500 watts. In both cases the generator will definitely consume fuel, but in both cases the generator must run at 3600 RPM to produce 60Hz current.
So as you can see, there is definitely wastage of fuel; not that high, but some amount of fuel does go to waste.
Well, now let’s understand the inverter generator. As I said earlier, the inverter generator produces power in three stages; first, it produces AC power, then converts it to DC power and then again converts it back to AC power.
This is especially helpful when you need less power from the inverter generator because the generator will rotate at a lower speed (consuming less fuel) and produce power with low frequency. Then the rectifier will convert it to DC power, and then the inverter circuit will convert it to 120V 60Hz power.
Let’s understand it by this example. Suppose you have an inverter generator that can supply 1000 watts continuously, and you want to run a 100-watt bulb. And then you want to run a 500-watt device on it. Now in the case of a 100-watt bulb, the inverter generator will burn less fuel (because it does not need to produce 60Hz supply; hence, the rotating speed will be very low) compared to the conventional generator. And in the case of a 500-watt device, the rotor will rotate accordingly (far less than 3600 RPM) to produce the required power.

[Also Read: Synchronous Generators vs. Induction Generators]

Noise Output

So now you know their difference in fuel efficiency, let’s understand how they differ in terms of noise output.
The generator produces noise mainly due to combustion of fuel, and rotation of mechanical gears. This noise increases when the load demand is increased because in order to cut those intensive magnetic fields of a stator, the rotor needs high torque. And that is why the high amount of fuel is ignited in the chamber and hence, noise production increases too.
The portable generator will make the same amount of noise up to 85% load capacity, but above that, its noise will increase even further. But in the case of an inverter generator, it automatically adjusts its speed according to power demand; thus, it will make less noise at low power requirements.
Moreover, the portable inverter generators are integrated with special mufflers and sound dampening materials, which helps in reducing the noise to a great extent.

So which generator should you use?

Well, the answer is complicated because it depends on your power requirements. As you know, the inverter generators are very expensive and they are designed to be portable and compact; thus, their power output is also low.
If you need a generator for regular use and that too for load demand above 60 or 70%, then you are better off buying a conventional generator because its initial cost is low. But if you need a quiet generator with clean power output, then you should opt-in for an inverter generator.