What is ECM Technology?

Kal Row

in a regular universal motor with brushes, the magnetic fields are commutated, i.e. moved along the circle or reversed so to speak, by the brushes – that is, the current in the rotor is opposite the current in the stator causing the poles to repel, moving the rotor to the next segment under the brushes, which again powers the rotor in reverse to the stator and moves it along … and so on and so on, these motors are powerful and cheap – the exist everywhere from your blender to you car’s starter, – but they make a racket, electrical noise, and the brushes ware out, and cant be immersed in liquids for cooling

enter the Electronically Cumulated Motor,
these motors have a powerful permanent magnet rotors, and the poles in the stator are switched along (or “COMUTATED”) electronically, by electronically watching the current and voltages of the stator.

so right off the top the motor uses half the current because the magnetic field in the rotor is a permanent magnet and essentially free energy, (or course the are inertial/friction loses but those are a drop in the hat) – now because we are watching and controlling the voltage and current in the windings we can do all sorts of things like – “constant pressure”, which works like this: all motors have “SILP”, that is, the rotor “slips” slightly behind the rotating magnetic field – the bigger the load the more the slip – until it stalls on a complete overload, and lets all the smoke out of the windings ;), – now, we can set this slip angle electronically and hold it, so that as zone valves close and the pressure builds, and the motor will slip more, which can be sensed by the current rising faster than the voltage in the stators – so, we lower the frequency to the stator’s rotating magnetic field to lower the speed, which drops the pressure and hence the slip angle with it – this happens very fast electronicaly, since motors move much slower than the speed of light - in fact in the hard disk of you computer which is an ECM motor, it varies the speed up and down a few timer per revolution to balance itself out – that why modern hard disks are so quiet,

strictly speaking though, an ECM motor does not have to have a permanent magnet rotor as you can electronically commutate induction motors too!


Now the Grundfos MAGNA’s adaptive mode, takes this a step further, by also having temp sensors that can measure the change in temp across the system, so, even if all the zone valve are open – but the water temp coming back is getting closer to the water temp going, it slows down, as you are not using the BTU’s, so why waste energy moving all that water, this feature is also built into the HydroBlock from hbx controls (http://www.hbxcontrols.com/products/hyd-0100.php) – while not an ecm motor itself – it still uses electricity very sparingly by direct delta-P/delta-T sensing – and is readily available and less expensive that either the wilo stratos or the grundfoss magna

Supply House Rick

Can somebody explain it?

It's seems to be pretty important to some people around here lately. Thanks!

Rick

singh

ECM

Well, to put it very simply, its a modulating motor.

ECM (electronic commutated motor) is a brushless DC motor with a permanent magnet rotor and a built in inverter. DC motors are more effcient than AC motors. They are also more expensive.

I'm sure others here will go into greater technical explaination.

Devan

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Mitch_4

go here

http://www.thedealertoolbox.com/home.php

You can get all kinds of information.

Mitch

Steve Thompson (ST)

ECM

Hi Rick.

There are a couple of ECM motor types. The typical fan type is indeed brushless DC. About 8 years ago larger HVAC circs were developed and are a have different technology.

Our Stratos and Stratos ECO use ECM (Electronically Communicated Motors) but the motors are AC. The key to how these circs work is they have permanent magnet rotors. The drive senses the difference between the magnetic field of the rotating rotor and the rotating magnetic field of the windings in the motor stator. As the system flow demand increases (zones open) the drive senses the torque difference at the impeller via the change in the magnetic field difference and speeds up by increasing the frequency to the motor. A nice by-product of this kind of ECM is 4 times the starting torque and soft start plus eliminating pressure compensated by-pass valves and no need to wire zone valves back to pumps due to extremely low dead head power. You can imagine how much more efficient driving a permanent magnet rotor is vs a standard non-magnetic rotor would be.

Neat stuff. More zones open, more heat required, more BTU’s and more flow required. Of course this works in reverse as the zones are satisfied.

If you have any additional questions or would like one of my training CD’s drop me an E Mail (steve.thompson@wilo-usa.com).

Supply House Rick

Thanks Steve!

Now that makes sense!

Rick

singh

Steve

Is it "Electronically Communicated Motors" or Electronically Commutated Motors?

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