Is Honda's main IMA motor AC or DC?

Are you sure?

Honda calls their IMA a "brushless DC motor". That is what they call it the in the brochures for the Insight, Civic and Accord hybrid. After doing a bit of research I've discovered that the motors are in fact brushless 3 phase AC motors.

Check out this pic:

http://www.greenhybrid.com/share/image190.html

This thread has the details:

http://www.insightcentral.net/forum/...pic.php?t=3080

See also:

http://www.insightcentral.net/encyclopedia/enmdm.html

and:

http://www.insightcentral.net/encycl...converter.html


I think the confusion is because the MDM is attached to a DC to DC converter. The DC to DC function supplys the 12V system with power. The inverter in the MDM supplies artificial 3 phase AC to the IMA motor. In regen mode the IMA motor supplies true 3 phase AC back to the MDM which converts it to DC to charge the big battery pack.

Near as I can tell all the Honda Hybrids work the same way.

Thanks for the update on this and the links. I think all of this is very interesting and seeing the information you linked to is good to know.

Billy

In fact there is no such thing as a brushless DC motor, in point of fact any brushless motor operates by using AC power, even those "12v DC Brushless Fans" in your computer use AC power to spin the fan, there is a tiny (just a few transistors) square wave multi-phase inverter inside, so the DC power that comes in is turned into AC before doing any work, thus it's really an AC motor.

The brushes in a true DC motor are connecting the rotating coils to the DC power, but the act of rotating is causing the polarity to change as different coils are energized, so it acts like AC, but uses DC directly, you might say like a mechanical inverter.

We should all tip our hats to Nikola Tesla for inventing the AC motor and modern generators, amongst a whole whack of other important discoveries, such as wireless communication and other things that we still aren't "ready" to use to this day.

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The motors we use in RC airplanes are also called "Brushless DC", but are in fact 3 phase AC motors that require a special controller. I think that industry is calling them DC because the power storage source is a DC batt.

Mike Kinnell
Sonic Blue FEH AWD
Go BLUE!

I guess it really does not matter what the motors are called so long as everyone understands that you can't just hook up DC to a "Brushless DC" motor and that such a motor needs a conroler that converts the DC to 3 phase AC.

I also fly electric planes and noticed that the Honda MDM looks just like a huge Jeti/Castle Creations. Not that it is at all important but I don't remember the motors in RC being called "Brushless DC" They usually just call em plain ole "Brushless".

See link:

http://www.hobby-lobby.com/brushless-motors.htm

When I see "Brushless DC motor" I also view the whole package.

Most of the time I see this used for fans, etc and consider the actual current on the coils as irrelivent.

For example as a hobbyist if I go buy a "Brushless DC Motor" fan, I'm concered with the actual input, which would be + - DC at the rated voltage/current.

If I go buy an AC fan motor it's likely an induction type and once again my concern is the input requirements of the whole package.

I see the term as "Brushless" as it contains no mechanical means that can wear out that supplies the rotor with power for coils, and the fact that the package has a DC input.

The HCH motor is brushless, and as far as I know is DC just like our tiny fan motors.

What's the actual current on the coils? I'd imagine its AC to reverse its magnetic field.
I'm counting here that the inverter is part of the motor, just like our fans, and the input is DC. A brushless DC motor.

This is the sticking point. Over at IC, John maintains that if the controller is built into the motor that you call it a DC brushless but if the controller is seperate you call it AC brushless or just brushless. The MDM is the inverter that drives the IMA motor and it is physically seperate from the motor. The two units are connected by 3 cables carrying 3 phase AC power from the MDM to the IMA motor. Hence my original assertion that the motor is AC.

Chrs over at IC is saying that the internal workings of the motor determine (historically) what the motor is called. He maintains that if a motor is fed 3 phase pure sine wave power and the rotor is an induction type with no magnets that the motor is called AC. If however the motor is fed "fake" AC from an inverter and the rotor has magnets (more like a traditional DC motor) that it is call "brushless DC".

I've come off the position that it is wrong to call the motor "brushless DC" but I still don't care for for that description as IMO it is missleading. I think they should drop the "DC" and just call it "brushless"

Why does it matter?

troy