Voltage regulator

[Greg Hermann]

>Greg Hermann wrote:
>>
>> >At 01:55 PM 1/2/99 -0500, you wrote:
>> >
>> >>
>> >>Hence, the proper answer of PWM.
>> >
>> >Exactly!
>> >The pump still sees full voltage, it just has it for a limited time!
>>
>> C'mon--the PWM switch LOWERS the AVERAGE voltage by switching teh FULL
>> voltage on and off rapidly. As I said, you want good smoothing of the
>> output, cuz the rapid pulsing IS what will dissassemble the windings!
>>
>> Regards, Greg
>> >
>> >===========================================================
>> >           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
>> >     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
>> >       I am Pentium of Borg...division is futile...you will be approximated.
>> >===========================================================
>DC motors designed for PWM control are of the "universal" variety, with
>laminated cores - capable of running on AC as well as DC - or permanent
>magnet field with laminated armatures. Yes, the inductance DOES tend to
>smooth out the peaks - but try running two identical motors at the same
>reduced "average" voltage - one with a pwm and one with a resistor. You
>know what you will find. Right, the PWM controlled motor will have
>significantly more torque, assuming the pwm controller is properly built
>and designed. Just try out an electronic controlled variable speed drill
>vs a resistance controlled variable speed drill.

OK--voltage relates to speed--current relates to torque. same as a shunt
wound DC motor. The PWM reduces the (average) voltage, but does not limit
the (average) current the way a resistor does. The picture is now coming
into focus a bit clearer! I still say a smoothing filter on the motor lead
side of the PWM switching device is very good for the motor. Likewise, a
filter upstream of the PWM switching device is good for everything else in
the neighborhood. (Like digital devices of one sort or another!) :-)

A couple of loops of power and motor, and even control leads around
(separate) ferrite cores is also not a bad idea, if you want to get serious
about reducing the noise.

Greg