What is the difference between Boost/Buck Controllers and Inverters/Transformers?

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#1 21684722 12 Jul 2020 18:43

David Fong David Fong

Anonymous

Post #1
21684722 12 Jul 2020 18:43

Dear Team,
I would like to understand the difference between Boost/Buck Controllers and Inverters/Transformers? Do both really amplify the power output or they only increase the Voltage and keeping the power output respectively to the power input?

Thank you for your help,David
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#2 21684723 12 Jul 2020 19:14

Maurizio Di Paolo Emilio Maurizio Di Paolo E...

Anonymous

Post #2
21684723 12 Jul 2020 19:14

I suggest you this link with a lot of material https://www.powerelectronicsnews.com/special/power-design-notes/
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#3 21684724 12 Jul 2020 23:43

David Fong David Fong

Anonymous

Post #3
21684724 12 Jul 2020 23:43

Dear Maurizio,
Thank you for your help, the link you sent me is very helpful, let me go through it and i will keep you posted.
Many thanksDavid
#4 21684725 12 Jul 2020 23:43

David Fong David Fong

Anonymous

Post #4
21684725 12 Jul 2020 23:43

Dear Maurizio,
Thank you for your help, the link you sent me is very helpful, let me go through it and i will keep you posted.
Many thanksDavid
#5 21684726 12 Jul 2020 23:44

David Fong David Fong

Anonymous

Post #5
21684726 12 Jul 2020 23:44

Dear Maurizio,
Thank you for your help, the link you sent me is very helpful, let me go through it and i will keep you posted.
Many thanksDavid
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#6 21684727 13 Jul 2020 11:25

David Ashton David Ashton

Anonymous

Post #6
21684727 13 Jul 2020 11:25

DavidA BOOST controller is an active electronic circuit (ie uses transistors/ICs) with a DC input and DC output voltage that is higher than the input voltage. Power out is equal to power in x efficiency (efficiency may be anything up to 95% or so)A BUCK controller is an active electronic circuit with a DC input and DC output voltage that is lower than the input voltage. Same remarks as above for efficiency.Boost/Buck controllers typically use inductors only, not usually .transformersAn INVERTER is a device with a DC input and an AC output. It will usually use similar circuits to buck/boost controllers, and also usually transformers. It's also an active electronic circuit.A TRANSFORMER is two coils using the same core, to transform AC voltages from one value to another. It is a passive device (ie no electronic circuitry) The coils will usually use different numbers of turn, so the output voltage is usually lower or higher than the input voltage. The core is usually laminated iron for low frequencies, ferrite for high frequencies, or even air for RF types.None of these devices amplify. An AMPLIFIER takes a small signal and converts it to a larger signal, and uses an external power source to provide the power for the increase.Hope this helps.
#7 21684728 13 Jul 2020 11:49

David Fong David Fong

Anonymous

Post #7
21684728 13 Jul 2020 11:49

Dear David,
Thank you for you excellent input, it is now very clear for me that for any of these devices the power input will always equal the power output, not considering efficiency losses.
Many thanksWarm regardsDavid
#8 21684729 18 Jul 2020 08:17

John David Heinzmann John David Heinzmann

Anonymous

Post #8
21684729 18 Jul 2020 08:17

Yes, I like to think of these all functionally as transformers of sorts. Respectively, the boost and buck converters are like step up and step down transformers but for DC, and the inverter is like a transformer between DC and AC (often variable). Ideally, power out is nearly equal to power in, thus current goes down (from input to output) when voltage goes up, and vice versa.-JD
#9 21684730 19 Jul 2020 19:29

David Fong David Fong

Anonymous

Post #9
21684730 19 Jul 2020 19:29

Many Thanks to all of you,
I have received clear explanations from different inputs to cover this topic.
Warm regards and continue the great work
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#10 21684731 02 Aug 2020 17:25

David Fong David Fong

Anonymous

Post #10
21684731 02 Aug 2020 17:25

Dear Mr. Ashton,
Trust you are doing well, though you have sent me a clear explanation on the differences between Transformers and Inverters and I have understood that in both cases the power input will always equal to the power output, but I still can't understand how a power inverter can convert a 12v DC to 220v AC, in this situation there is definitely a power increase. Kindly if you could help me to understand if Inverters can increase Power? I went through the working principles of an Inverter and I understood that it is mainly based on Magnetic Induction, which is used by Transformers! I am really confused and Thank you in Advance.
#11 21684732 02 Aug 2020 18:14

David Ashton David Ashton

Anonymous

Post #11
21684732 02 Aug 2020 18:14

Hi David,
OK, an inverter still has efficiency less than 100% and does not create new power. For example if you have an inverter 12V DC to 220V Ac that can supply 120 Watts. At 220V, 100 watts is about 550 mA. But at 12V, 100W is 10A and that is what it will draw from the battery. In fact it would probably be around 12A allowing for an efficiency under 100%. An inverter will usually have a transformer in it to step up the 12V DC to 200V AC, along with some electronics to convert the 12VDC to AC for the input to the transformer.It's easy enough to make a square wave inverter using two transistors run as a multivibrator, and a split input winding. But an inverter putting out a pure sine wave will use much more sophisticated electronics to provide a sine wave output.A transformer merely change one AC voltage to another. Again the power at each side will be the same (allowing for efficiency which in a good transformer should be well above 90%).This is a huge subject, but hope this helps...Cheers // David
#12 21684733 02 Aug 2020 20:13

David Fong David Fong

Anonymous

Post #12
21684733 02 Aug 2020 20:13

Hi Mr. Ashton, Yes I do understand that it is a huge subject but i am not looking to go into more details but just to understand the working principles and I must Thank you for helping me on that. So my confusion came from the fact that every devices have their own specific Amp value to work properly and I could not understand how they could work from an Inverter, but now I understand that the power required is drained from the 12VDC source. so I can conclude that an Inverter will not work on any type of DC source, but mostly from a constant generating power source. even if I am wrong no worries but now i have understood the idea behind it and Many Thanks again
#13 21684734 03 Aug 2020 05:25

David Ashton David Ashton

Anonymous

Post #13
21684734 03 Aug 2020 05:25

David... I'd suggest you review your basics... Power = Volts x Amps. For AC you should use the RMS values, which a good meter will read. For all the devices you initially mentioned (Boost/Buck controllers, inverters and even the passive transformers) Power out = Power in x efficiency.Inverters will usually have a specified input voltage, eg the common 12V DC ones you see for powering mains devices in your car or while camping, or much higher voltage ones (can take a wide input voltage up to a few hundred volts) for use with solar power rooftop installations
The solar grid-connected inverters have to not only generate 220V, but do it in the right phase and with just enough voltage difference from the mains that they can effectively feed power back into the grid. If you look inside one of those there are LOTS of electronics to accomplish this.As I say, a huge subject.Best // David
#14 21684735 10 Sep 2020 15:11

jessewalter375 jessewalter375

Anonymous

Post #14
21684735 10 Sep 2020 15:11

Buck Boost Transformer:-
When it comes to power conversion, the buck boost or “push pull” transformer application is well known. The buck boost transformer configuration is widely used in converting direct current (D.C.) voltage into another value of D.C. voltage, and in inverters. Inverters convert direct current into alternating current (A.C.). The push pull transformer is usually the preferred choice in high power switching transformer applications exceeding one kilowatt. It is usually used in a circuit known as a “forward converter” circuit,and it may also be referred to as an “inverter”, “D.C. converter”, “buck”, “feed forward”, and others. A basic “forward converter” transformer circuit is illustrated in Figure 1A. It is not a push pull transformer application. The output inductor reduces ripple voltage. Pulse width modulation is used to control the value of the output voltage.

Inverter:-
A power inverter, or inverter, is a power electronic device or circuitry that changes direct current to alternating current. The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry.
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Topic summary

✨ Boost and Buck controllers are active electronic DC-DC converters that respectively increase or decrease DC voltage while maintaining power output approximately equal to power input multiplied by efficiency (up to about 95%). They typically use inductors and transistors/ICs but not transformers. Inverters convert DC input to AC output, often employing similar switching circuits combined with transformers to step up voltage. Transformers are passive devices consisting of two coils on a shared magnetic core that convert AC voltages by changing coil turns ratio without electronic components, maintaining power balance minus losses. Power output in all these devices does not exceed power input, considering efficiency losses. Inverters, such as 12V DC to 220V AC types, increase voltage but draw proportionally higher current from the DC source, thus not creating additional power. Advanced inverters produce sine wave AC outputs using sophisticated electronics, while simpler designs may generate square waves. Buck-boost transformers, often used in high-power switching applications and forward converter circuits, facilitate DC voltage conversion and inverter functions through pulse width modulation and inductive filtering. Solar grid-tied inverters incorporate complex electronics to synchronize output phase and voltage with the grid. Overall, these devices transform voltage and current characteristics but do not amplify total power beyond input limits.

FAQ

TL;DR: DC‑DC buck/boost converters can hit about 95% efficiency; “None of these devices amplify.” They trade voltage for current, so power out ≈ power in minus losses. This FAQ explains how bucks, boosts, inverters, and transformers differ, with clear examples. [Elektroda, Anonymous, post #21684727]

Why it matters: If you’re sizing power gear or troubleshooting sagging voltage, knowing that converters don’t create power prevents burnt parts and dead batteries.

Quick Facts

Boost = higher DC output than input; active electronics; typical peak ≈95% efficiency. [Elektroda, Anonymous, post #21684727]
Buck = lower DC output than input; active electronics; efficiency similar to boost stages. [Elektroda, Anonymous, post #21684727]
Inverter example: 100 W at 220 V ≈ 0.55 A; same 100 W from 12 V draws ≈10–12 A. [Elektroda, Anonymous, post #21684732]
Transformers are passive AC–AC devices; good units run well above 90% efficient. [Elektroda, Anonymous, post #21684732]
Universal rule: Power out = Power in × efficiency (use RMS for AC). [Elektroda, Anonymous, post #21684734]

What’s the difference between a buck, a boost, an inverter, and a transformer?

A boost raises DC voltage; a buck lowers DC voltage. Both are active switch-mode stages. An inverter converts DC to AC, often using similar switch-mode blocks plus a transformer. A transformer passively shifts AC voltage using two windings on a common core. None of them create power. [Elektroda, Anonymous, post #21684727]

Do any of these devices amplify power?

No. They convert voltage and current while conserving power minus losses. “None of these devices amplify.” Amplifiers increase signal power by drawing extra energy from a supply, which is different from conversion. [Elektroda, Anonymous, post #21684727]

How can a 12 V inverter run a 220 V appliance without increasing power?

It raises voltage but draws more current from the 12 V source. Example: 100 W at 220 V is about 0.55 A, but at 12 V that same 100 W needs around 10 A, or about 12 A including losses. The inverter doesn’t create power; it trades current for voltage. [Elektroda, Anonymous, post #21684732]

What efficiency should I expect from buck/boost converters?

Expect high efficiency, with good designs reaching about 95%. Actual efficiency depends on components, switching frequency, magnetics, and load. Plan thermal and input current for real, not ideal, efficiency. [Elektroda, Anonymous, post #21684727]

How efficient are transformers?

Quality transformers are highly efficient. The thread cites “well above 90%” for good units. Core material, frequency, and loading affect losses. Ferrite cores suit higher frequencies; laminated iron cores suit mains frequencies. [Elektroda, Anonymous, post #21684732]

Do buck/boost controllers use transformers?

Typical buck and boost regulators use inductors, not transformers. Some topologies add transformers for isolation or large ratios, but the common non‑isolated buck/boost stages are inductor‑based. [Elektroda, Anonymous, post #21684727]

What does RMS mean for AC power calculations?

Use RMS (root mean square) voltage and current when calculating AC power. The basic relation is Power = Volts × Amps, using RMS values. Good meters report RMS, which makes comparisons to DC straightforward. [Elektroda, Anonymous, post #21684734]

What’s inside an inverter?

A typical design includes switching electronics to generate AC from DC and a transformer to step voltage as needed. Simple units output a square wave. Pure sine wave models add more sophisticated control to shape the output. [Elektroda, Anonymous, post #21684732]

Quick calc: How many amps from 12 V for a 100 W load?

About 10 A at ideal efficiency, and around 12 A allowing for losses. As voltage increases at the output, input current rises to conserve power. This is why cabling and fusing on the 12 V side must handle high current. [Elektroda, Anonymous, post #21684732]

Can I power an inverter from any DC source?

Use the specified input voltage range. Car inverters target about 12 V. Solar inverters may accept a wider DC range and must synchronize phase and voltage when grid‑tied. Without proper phase and voltage offset, they won’t feed the grid. [Elektroda, Anonymous, post #21684734]

Is a buck‑boost “transformer” the same as a buck‑boost converter?

Terminology varies. Some switch‑mode literature calls push‑pull or forward‑converter transformer stages “buck‑boost” applications. They’re magnetic stages within DC‑DC or inverter systems, not the simple non‑isolated buck‑boost regulator. Context matters. [Elektroda, Anonymous, post #21684735]

What is a forward converter in plain terms?

It’s a switched‑mode power supply topology that uses a transformer and pulse‑width modulation to produce a regulated DC output. An output inductor reduces ripple. Designers may refer to related stages with terms like inverter, DC converter, or buck. [Elektroda, Anonymous, post #21684735]

How do I calculate inverter input current from a known AC load?

Compute load power: P_load = V_out × I_out (use RMS if AC).
Estimate input power: P_in ≈ P_load ÷ efficiency.
Compute input current: I_in ≈ P_in ÷ V_in. Example: 100 W ÷ 0.85 ≈ 118 W; at 12 V, I_in ≈ 9.8 A. [Elektroda, Anonymous, post #21684734]

Why do people think converters “amplify”?

Voltage may rise dramatically, which looks like amplification. But current falls so power stays similar minus losses. True amplifiers use an external supply to increase signal power. Converters only trade voltage and current. [Elektroda, Anonymous, post #21684727]

What happens if my inverter isn’t a pure sine wave?

Functionally, simpler designs can output a square wave, while pure sine models use more complex electronics. Choice affects compatibility and performance, but both still obey power conservation. “It’s easy enough to make a square wave inverter.” [Elektroda, Anonymous, post #21684732]