[NSRCA-discussion] ESC

[Ken Thompson]

George,

It uses the Flux Capacitor, every one knows that <VBG>


----- Original Message ----- 
From: <glmiller3 at suddenlink.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, July 25, 2007 4:49 PM
Subject: Re: [NSRCA-discussion] ESC


> Fred,
>
> I can see how that senses the rpm to adjust the "phasing speed" but how 
> does it sense the "flux" of the magnets?
>
> George
> ---- Fred Huber <fhhuber at clearwire.net> wrote:
>> The simulated AC supplied by the ESC leaves one phase "dead" appx 1/4 of 
>> the
>> time.  Durring that time, the ESC senses the "counter EMF" generated by 
>> the
>> magnets passing the de-energized windings.
>>
>> If the ESC didn't have this feedback, it would need a hall sensor to 
>> detect
>> rpm.  Early 3-phase ESC's had the hall sensors. (and actually thats a 
>> better
>> way to do it)
>>
>> ----- Original Message ----- 
>> From: <glmiller3 at suddenlink.net>
>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>> Sent: Wednesday, July 25, 2007 9:35 AM
>> Subject: Re: [NSRCA-discussion] ESC
>>
>>
>> > So (to check my understanding at the risk of being repetitive)- the ESC
>> > changes the voltage to maintain the magnetic flux of the rotor and 
>> > changes
>> > the frequency to increase the RPM ?!
>> >
>> > So how does it detect the magnetic flux?
>> >
>> > And how come your running a 4stroke if you are such an electric 
>> > guru?<G>
>> >
>> > G
>> > ---- Richard Lewis <humptybump at sbcglobal.net> wrote:
>> >> George,
>> >>
>> >> It is the unit of measure related to the strength of the magnetic 
>> >> field
>> >> produced by the windings.
>> >>
>> >> Richard
>> >>
>> >> -----Original Message-----
>> >> From: nsrca-discussion-bounces at lists.nsrca.org
>> >> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
>> >> glmiller3 at suddenlink.net
>> >> Sent: Wednesday, July 25, 2007 6:10 AM
>> >> To: NSRCA Mailing List
>> >> Subject: Re: [NSRCA-discussion] ESC
>> >>
>> >> Richard,
>> >>
>> >> What is the "flux" in the motor?
>> >> Thanks
>> >> George
>> >> ---- Lance Van Nostrand <patterndude at tx.rr.com> wrote:
>> >> > Thanks Richard.  I thought the motors were multiphase DC motors and 
>> >> > the
>> >> ESC sequentially energized the windings at the desired rpm and 
>> >> increased
>> >> the
>> >> voltage when the stator fell too far behind.
>> >> > --Lance
>> >> >
>> >> >   ----- Original Message ----- 
>> >> >   From: Richard Lewis
>> >> >   To: 'NSRCA Mailing List'
>> >> >   Sent: Tuesday, July 24, 2007 4:57 PM
>> >> >   Subject: Re: [NSRCA-discussion] ESC
>> >> >
>> >> >
>> >> >   Nat,
>> >> >
>> >> >
>> >> >
>> >> >   The ESC has a set of transistors arranged in a three phase bridge
>> >> arrangement.  The 3-phase bridge is supplied by the DC from the 
>> >> batteries
>> >> and through a complex switching algorithm it synthesizes a three phase 
>> >> AC
>> >> voltage that is applied to the motor windings.  The motor is a 
>> >> permanent
>> >> magnet synchronous AC motor.  The speed of a synchronous machine is
>> >> directly
>> >> proportional to the speed of the rotating magnetic field applied.  The
>> >> voltage applied to the motor is in short pulses at a fixed frequency 
>> >> know
>> >> as
>> >> the carrier frequency.  The width of these pulses is modulated (pulse
>> >> width
>> >> modulation or PWM) to produce an average voltage waveform that
>> >> approximates
>> >> the sinusoidal shape required to operate the motor efficiently.  The
>> >> amplitude of the synthesized sinusoidal voltage waveform is varied
>> >> proportionally with the frequency to produce the proper flux within 
>> >> the
>> >> motor for a given frequency.
>> >> >
>> >> >
>> >> >
>> >> >   To answer the question, the speed controller varies the frequency 
>> >> > to
>> >> control the speed of the motor.  The ESC varies the voltage to control
>> >> the
>> >> flux in the motor.
>> >> >
>> >> >
>> >> >
>> >> >   The single phase case would cause the connected windings to draw
>> >> excessive current without the third phase to balance the effective
>> >> impedance
>> >> in the motor winding and take out the transistors easily.
>> >> >
>> >> >
>> >> >
>> >> >   In modern industrial Variable Frequency Drives (VFD) the 
>> >> > transistors
>> >> have many protection mechanisms from fuses which are relatively slow 
>> >> to
>> >> an
>> >> internal gate cutoff that can stop excessive current within a single
>> >> pulse
>> >> to protect the transistor from damage due to excessive current.  In
>> >> comparison, the ESC's we use have little or no protection from 
>> >> excessive
>> >> current.
>> >> >
>> >> >
>> >> >
>> >> >   Richard
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> ----------------------------------------------------------------------------
>> >> --
>> >> >
>> >> >   From: nsrca-discussion-bounces at lists.nsrca.org
>> >> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Nat 
>> >> Penton
>> >> >   Sent: Tuesday, July 24, 2007 3:26 PM
>> >> >   To: NSRCA Mailing List
>> >> >   Subject: [NSRCA-discussion] ESC
>> >> >
>> >> >
>> >> >
>> >> >   OK, I need educating.
>> >> >
>> >> >   I realize the ESC converts single phase to three phase. Does it 
>> >> > alter
>> >> the speed of the motor by changing  amplitude or frequency ?
>> >> >
>> >> >
>> >> >
>> >> >   Why did it burn up the ESC (fast, like in quick) when I accidently
>> >> single phased ?           TIA   Nat
>> >> >
>> >> >
>> >> >
>> >> >
>> >> ----------------------------------------------------------------------------
>> >> --
>> >> >
>> >> >
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