DC Inverters and Rectifiers: Understanding the Terminology

[JimTheHVACGuy]

I'm no Electrical Engineer. But I do have a lot of questions pertaining to Electrical theory. One topic as of late that has the cogs in my brain turning, are Converters.

For instance, I work on Comfort Cooling and Heating Systems for a living, as of the last 3-4 years DC Inverter Heat Pumps have become a huge factor in my line of work. So, my question that has been aching my head, why would the call them DC Inverters? The process of CONVERTING AC to DC is Rectification, is it not? The CONVERTING of DC to AC is done by use of an Inverter. WHY DO THE CALL THE HEAT PUMP CIRCUIT BOARD A DC INVERTER??

Has my whole life been a lie? Is there some explanation that could be given to me to make this make sense? Or am I just an ignorant fool? Why didn't they name them DC Rectifiers?

 

[Drakkith]

From wikipedia's article on power inverters:

Early inverters
From the late nineteenth century through the middle of the twentieth century, DC-to-AC power conversion was accomplished using rotary converters or motor-generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas-filled tubes began to be used as switches in inverter circuits. The most widely used type of tube was the thyratron.

The origins of electromechanical inverters explain the source of the term inverter. Early AC-to-DC converters used an induction or synchronous AC motor direct-connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame. The result with either is AC-in, DC-out. With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectified AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC. Hence an inverter is an inverted converter.

 

[Baluncore]

Welcome to PF.

Has my whole life been a lie?

Probably, yes.

 

[TonyStewart]

If you talk to an Electrical Engineer who does hardware design for Logic, ask for a 3.3V Inverter. It is just a logic chip that amplifies to the opposite limit value defined for 0 and 1 in voltage. There are dozens of these logic types. Six in a package cost a few pennies in volume.

JimTheHVACGuy said:
Has my whole life been a lie?

Do not fret about the many uses of the same word in English.

Many industries invert, convert, transform and regenerate.

Heat pumps are an example of using common fluid heat-sharing interfaces to conserve thermal power on air-fluid exchange by reversible flow in seasons or using the earth's core for cooling buildings.

These concepts highlight the dynamic nature of various industries, where companies strive to adapt, innovate, and respond to evolving challenges and opportunities. By embracing inversion, conversion, transformation, and regeneration, industries can drive progress, sustainability, and economic growth in a rapidly changing world.

Ok. nuf said... Blanket name might confuse people like "conversion" She/his ;)

 

[JimTheHVACGuy]

Wow. Thank you for your responses. Especially you Baluncore :) You all are very intelligent individuals. I honestly didn’t expect such detailed responses. So am I just getting hung up on “name labeling”? I’m gonna assume that I am, but this all leads into my next question, and I’m going to reference Drakkith’s resource material, so in the application of using a M-G Set, it takes AC in - DC out. And then theoretically runs backwards taking the DC Voltage generated in - AC out? If that’s the case then I totally get it. But as a novice Electrical Theory Connoisseur, I have to ask, wouldn’t it make more sense to use a Rectifier then an Inverter?

 

[TonyStewart]

M-G Set, wouldn’t it make more sense to use a Rectifier then an Inverter?

In AC inverters inside UPS sets the energy is stored in a battery. When the power gets too big, the stored kinetic energy in M-G sets may be cheaper to provide the low impedance and low loss to reduce load regulation errors.

 

[Drakkith]

But as a novice Electrical Theory Connoisseur, I have to ask, wouldn’t it make more sense to use a Rectifier then an Inverter?

That depends on the context. Cost effectiveness, cost, reliability, power requirements, size, availability, and many other factors come into play when deciding what is best to use to convert power from one form to another.

In the Air Force we had big motor generators that converted 120V 60 Hz electricity to 400 Hz (I can't remember the voltage) for use in testing and powering our cruise missiles, as the B-52 bombers they would be loaded onto used 400 Hz ac power internally (at least for powering weapons). I always thought it odd that we took AC power from the grid, used it to power a motor that was used to power another generator just to convert it to a higher frequency. But I later realized there likely just wasn't a cheaper and easier way of doing it for what we needed it for.

 

[Tom.G]

But I later realized there likely just wasn't a cheaper and easier way of doing it for what we needed it for.

And it is a LOT easier, cheaper, (and less frequent in those days) to replace brushes and dress a worn commutator that to 'do it electronically'!

Less training too.

 

[russ_watters]

For instance, I work on Comfort Cooling and Heating Systems for a living, as of the last 3-4 years DC Inverter Heat Pumps have become a huge factor in my line of work. So, my question that has been aching my head, why would the call them DC Inverters? The process of CONVERTING AC to DC is Rectification, is it not? The CONVERTING of DC to AC is done by use of an Inverter. WHY DO THE CALL THE HEAT PUMP CIRCUIT BOARD A DC INVERTER??

Has my whole life been a lie? Is there some explanation that could be given to me to make this make sense? Or am I just an ignorant fool? Why didn't they name them DC Rectifiers?

Do you have a link to somewhere that says that? Because what you describe is wrong:

AC variable speed control = inverter.

DC variable speed control = ECM (there may be other methods).