00:00Have you ever stopped to think about why the fan in your house only has two or three speeds?
00:06While in industrial environments it's possible to adjust an electric motor speed with surgical precision?
00:12The answer to this question lies in a device that, although few people know about it,
00:17is present in almost every place where there is an electric motor running.
00:23The variable frequency drive.
00:31Hey engineering enthusiasts! Today we're going to talk about equipment that revolutionized the global industry.
00:37And it's probably closer to you than you think.
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01:07To understand what a variable frequency drive is, we need to go back to the end of the 19th century.
01:13More specifically, in the one year, 1888, when the Serbian inventor Nikola Tesla patented the three-phase induction motor.
01:22This motor, which operated with alternating current, was a stroke of genius.
01:28Simple, robust and efficient.
01:30So efficient, that even today, the vast majority of electric motors in the world operate based on the principle that
01:37Tesla established.
01:38But this motor had an important limitation.
01:42It rotated at a fixed speed, determined by the frequency of the power grid that supplied it.
01:47But what is this so-called frequency?
01:50Here's a quick explanation.
01:52The electrical energy that comes to our outlets is called alternating current, which means it changes direction several times per
01:59second.
01:59Here in Brazil, the power grid operates at 60 Hz, which means the current reverses direction 60 times every second.
02:08This frequency is what determines the speed at which the electric motor spins.
02:13If the frequency is 60 Hz, the motor will spin at a fixed maximum speed.
02:20But what would happen if we could change this frequency?
02:23That's exactly where the variable frequency drive comes in.
02:26Also known by the acronym VFD.
02:29From the English term, variable frequency drive.
02:32This electronic device has the ability to take the power from the electrical grid with its fixed frequency of 60
02:40or 50 Hz and turn it into power at a variable frequency.
02:44With this, it's possible to make the motor run slower or faster according to the need.
02:49But how does it do that?
02:51The variable frequency drive works in three stages.
02:54The first one is rectification.
02:56In this phase, the alternating current that comes from the grid is converted into direct current.
03:02Think of it like your cell phone charger, which takes the power from the outlet and turns it into a
03:08continuous flow of energy to charge the battery.
03:11In the inverter, electronic diodes do this conversion work.
03:17The second stage is called the direct current bus.
03:20It's basically a filter that smooths out the converted energy, storing this direct current in capacitors.
03:28The goal here is to turn it into a clean and stable energy source for the next phase.
03:34The third and final stage is the inversion, which gives the equipment its name.
03:39In this phase, electronic components called IGBT, which work as extremely high-speed electronic switches, turn the direct current on
03:49and off thousands of times per second.
03:52This process is controlled by a technique called PWM or Pulse Width Modulation.
03:58The result of this is that from the direct current, we create a new alternating current, but now with the
04:06frequency and voltage that we want.
04:08It's as if the inverter is drawing a new electrical wave from scratch, cutting and stitching the current into pieces
04:16so small that the motor perceives it as perfectly continuous and smooth energy.
04:22But why is all this so important?
04:24To understand the real impact of the variable frequency drive, imagine a water pump in a residential building.
04:31Without the inverter, the pump motor always runs at maximum speed, regardless of whether it is supplying a water tank
04:39or not.
04:40To control the amount of water, a valve is used to restrict the flow, like partially covering the end of
04:46a hose.
04:47Less water comes out, but the motor keeps working at maximum.
04:51With the variable frequency drive, instead of restricting the flow with a valve, the motor speed itself is reduced.
04:58If less water is needed, the motor turns more slowly, consuming only the energy necessary for that moment.
05:05This makes a huge difference in energy consumption.
05:08Studies show that reducing motor speed through the variable frequency drive can generate considerable energy savings.
05:16Especially in applications like pumps, fans and compressors.
05:21This happens because the power consumed by this equipment varies with the cube of the speed.
05:27Which means that a small reduction in motor speed results in a much greater reduction in energy consumption.
05:35But is the variable frequency drive only used to save energy?
05:38Actually, no.
05:40The variable frequency drive also allows the motor to accelerate and decelerate smoothly and in a controlled way.
05:47Which reduces the mechanical weight of components like gears, belts and shafts.
05:52Think about how it's different to accelerate a car all at once by flooring the gas pedal versus gradually increasing
05:58the speed.
05:59Think about it.
06:00The engine and all the components experience much less stress when the acceleration is gradual.
06:06Besides that, the inverter provides electronic protection to the motor, being able to detect overloads, imbalances and faults, shutting down
06:14the system before something more serious happens.
06:17But where else do we find this equipment in our daily lives?
06:20Well, they're in more places than you might think.
06:24In your home's air conditioner, for example.
06:27Inverter models use exactly this technology to adjust the compressor speed according to the room temperature.
06:36Instead of turning the motor on and off all the time.
06:39In elevators, they provide smooth starts and stops, without those uncomfortable jolts.
06:45On conveyor belts, they allow you to adjust the speed according to production needs.
06:51In irrigation systems, they control the water flow precisely.
06:56And even in modern washing machines, the drum rotation is controlled by an inverter.
07:01But if this technology is so advantageous, why doesn't every electric motor have an inverter?
07:07The answer involves cost and complexity.
07:10A variable frequency drive is a sophisticated electronic device, which requires a higher initial investment than conventional direct starting.
07:19In addition, it generates some heat during the energy conversion process, which means that a small part of the energy
07:27is lost as heat and needs to be dissipated.
07:30In applications where the motor always needs to run at maximum speed, without variation, the inverter can be an unnecessary
07:37expense.
07:38But what about the future?
07:39With the advancement of power electronics and the growing concern for energy efficiency around the world,
07:45variable frequency drives are becoming increasingly accessible and common.
07:51What used to be equipment restricted to large industries is now present in household appliances, residential climate control systems,
07:59and increasingly in renewable energy applications.
08:03equipment that used to simply turn on and off can now operate intelligently, adjusting their energy consumption to the actual
08:11needs at that moment.
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08:37And you, have ever stopped to think that behind that air conditioner with the inverter label, there's all this engineering
08:44behind a variable frequency drive?
08:46Or that the elevator that goes up smoothly owes that to a device that controls the frequency of the electric
08:53power?
08:54Leave a comment telling us which applications surprise you the most.
08:58And have you ever heard of a variable frequency drive before this video?
09:02Right here are two interesting videos you should watch to learn more and satisfy your curiosity.
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09:14That's it engineering lovers, big hug and I'll see you in the next video.
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