Re: Pancake servo motors?

Brian,

Tempting but:

1. Low efficiency. The magnets are cantilevered rather than
cylindrical. This mechanically non-rigid shape makes for a much
larger air gap which lowers efficiency. These motors often have no-
load currents in the several amp range versus 200 mA or so for an
equivelent standard motor.

2. The low motor inertia advantage is quickly swamped out when a real-
life inertial load is applied.

3. The low armature inductance makes driving the motor more
complicated. Usually large series chokes must be used to keep
switching ripple currents managable.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "bsptrades" <bspunkar@a...> wrote:
>
>
> Hi all I have been exploring various refits and following along
with
> various threads bu I
> don't see anyone mention the ironless type pancake motors.
>
> For electric controls we have been using the ironless pancake
style
> motors exclusively
> for years now. These motors such as the Kollmorgen servodisc or
> Infranor motors would
> seem also ideal for high performance servo systems on machine
tooling.
>
> The rotor design provides almost zero cogging , very long brush
life
> in brushed models due to the low inductance, very high acceleration
> rates and peak torque. It also seems the flat package would just
look
> nice compared to a big long servo motor sticking out in some
> applications.
>
> Does anyone have experience as to why these type motors are not
> appropriate I really don't see a down side other than the diameter
> and non NEMA mount which would seem easy enough to get around?
>
> Anyhow just a question as there are a lot of experienced folks out
> here.
>
> Brian S Punkar
> BSP