Re: [TCML] Treadmill Motor Question

[Yurtle Turtle <yurtle_t@xxxxxxxxx>]

Thanks. Yes, it's a permanent magnet DC motor. It came with a speed controller, that was part of the treadmill. I'm assuming it's duty cycle and cooling fan are matched for each other.

I was wondering if filter caps on full wave rectification would be necessary (in case I fry my DC speed controller). I guess my question was mixing apples and oranges, and am not that familiar with VFDs, but always assumed the filter caps were for the DC component, and that the fake AC it outputs is not a lot cleaner than full wave rectified DC, though it depends on the number of pulses.




________________________________
 From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx 
Sent: Tuesday, September 10, 2013 9:31 AM
Subject: Re: [TCML] Treadmill Motor Question
 

On 9/10/13 5:30 AM, Yurtle Turtle wrote:
> Question for the list experts. If one were to employ a DC rsg motor
> with full wave rectification, are filter caps needed? Is the ripple
> any worse than pulsed AC from an inverter or pulsed DC from a cheap
> SCR speed controller?
>

You're talking about a brush DC motor, right?

Basically, you're relying on the inductance and mechanical inertia for 
"filtering".

The only thing I've noticed when doing this kind of thing is that the 
harmonic content is higher, so there's a bit more heating of the 
windings and/or noise (hum from the vibrations).

This is more of an issue with the SCR controller (waveform with lots of 
sharp edges) than, say, variac and a bridge.
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