C
Clive
Guest
In message <kif8k1$ddg$2@news.albasani.net>, Bimmer Owner
<dontaskfor@mymail.com> writes
Clive
<dontaskfor@mymail.com> writes
--
Clive
Guest
On Sat, 23 Mar 2013 10:48:27 +0000, Clive <clive@yewbank.demon.co.uk>
wrote:
kick-back. Virtually all battery operated variable speed power tools
use PWM. So do virtually all electric bicycles with brush motors and
the vast majority of electric forklifts.
In fact, just about any application of a brush type DC motor that
requires reasonable speed control has switched to PWM control of some
sort over the last 20 years, including power wheel chairs (except
those using 3 phase brushless motors)
wrote:
a flywheel diode is part of the "system" to handle the inductive
kick-back. Virtually all battery operated variable speed power tools
use PWM. So do virtually all electric bicycles with brush motors and
the vast majority of electric forklifts.
In fact, just about any application of a brush type DC motor that
requires reasonable speed control has switched to PWM control of some
sort over the last 20 years, including power wheel chairs (except
those using 3 phase brushless motors)
M
Michael A. Terrell
Guest
jim beam wrote:
Sure it can, if you're nothing more than a low grade grease monkey.
Your checks always bounce.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
Sure it can, if you're nothing more than a low grade grease monkey.
Your checks always bounce.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
M
Michael A. Terrell
Guest
clare@snyder.on.ca wrote:
Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
M
Michael A. Terrell
Guest
Bimmer Owner wrote:
It should generate less heat at low speeds, if it is PWM.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
It should generate less heat at low speeds, if it is PWM.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
Guest
On Sat, 23 Mar 2013 22:27:41 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:
the lighter duty stuff.
<mike.terrell@earthlink.net> wrote:
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.
M
Michael A. Terrell
Guest
tm wrote:
I've seen 20W power resistors in TO-220 packages.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
I've seen 20W power resistors in TO-220 packages.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
M
Michael A. Terrell
Guest
clare@snyder.on.ca wrote:
Is that cheaper than roll your own?
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
Is that cheaper than roll your own?
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
S
Scott Dorsey
Guest
Michael A. Terrell <mike.terrell@earthlink.net> wrote:
actual transistors in the photos, just spots from which they were removed).
But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.
any big protection diodes in there either.
If it's a RoHS soldering issue, though, I would not be surprised.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).
But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.
This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.
If it's a RoHS soldering issue, though, I would not be surprised.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
J
Jamie
Guest
Scott Dorsey wrote:
This lowers the Q significantly giving you a voltage drop of course,
but it also reduces electrical noise and helps suppress the wheeling
voltages.
Blower motors in this case are normally designed to operate lets say
8 volts for example, for full RPM.
I learned this years ago when going through the pain of removing the
blower in an air box of a Chrysler product, only to find there was
nothing wrong with the motor. Symptoms led on to the fact there was
since the output of the speed control circuit was alive and happy but
no obvious connection to the motor. If I had unplugged it from the air
box before pulling that all apart, I would of noticed it.
The problem was the resistor wire in the harness which had open at the
crimp point, also in the harness.
Jamie
the motor connection at the blower box.
This lowers the Q significantly giving you a voltage drop of course,
but it also reduces electrical noise and helps suppress the wheeling
voltages.
Blower motors in this case are normally designed to operate lets say
8 volts for example, for full RPM.
I learned this years ago when going through the pain of removing the
blower in an air box of a Chrysler product, only to find there was
nothing wrong with the motor. Symptoms led on to the fact there was
since the output of the speed control circuit was alive and happy but
no obvious connection to the motor. If I had unplugged it from the air
box before pulling that all apart, I would of noticed it.
The problem was the resistor wire in the harness which had open at the
crimp point, also in the harness.
Jamie
J
jim beam
Guest
On 03/20/2013 09:13 PM, jim beam wrote:
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.
that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.
--
fact check required
well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.
that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.
--
fact check required
A
amdx
Guest
I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek
T
tm
Guest
"amdx" <amdx@knologynotthis.net> wrote in message
news:41097$514f2120$18ec6dd7$30905@KNOLOGY.NET...
Even going to 40 to 60 kHz makes the magnetics smaller. We still do not know
what is under the PCB for that unit.
tm
news:41097$514f2120$18ec6dd7$30905@KNOLOGY.NET...
That would also make the LPF very much smaller.
Even going to 40 to 60 kHz makes the magnetics smaller. We still do not know
what is under the PCB for that unit.
tm
Guest
On Sun, 24 Mar 2013 02:28:00 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:
wiring harness.
<mike.terrell@earthlink.net> wrote:
for the guys who can't figure out how to do it without butchering the
wiring harness.
J
Jamie
Guest
amdx wrote:
Jamie
Jamie
M
Michael A. Terrell
Guest
clare@snyder.on.ca wrote:
That type shouldn't be allowed to own any tools. They generally do
more damage than good. If they do get something to work, it rarely lasts
because they have no clue what because the problem.
I've seen too many vehicles that some idiot cut and patched back
together. One stepvan I bought years ago had a damaged harness and I
talked them down almost $1000 on the price. It was coming off lease
from a fleet, and they wanted to fix it themselves. i pointed out that
if they could repair it properly, it wouldn't be in that condition.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
That type shouldn't be allowed to own any tools. They generally do
more damage than good. If they do get something to work, it rarely lasts
because they have no clue what because the problem.
I've seen too many vehicles that some idiot cut and patched back
together. One stepvan I bought years ago had a damaged harness and I
talked them down almost $1000 on the price. It was coming off lease
from a fleet, and they wanted to fix it themselves. i pointed out that
if they could repair it properly, it wouldn't be in that condition.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
M
Michael A. Terrell
Guest
Scott Dorsey wrote:
All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.
Have you looked at the National Semiconductor (Now part of T.I)
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Sometimes Friday is just the fifth Monday of the week.
S
Scott Dorsey
Guest
In article <kin5r4$pi1$1@dont-email.me>, jim beam <me@privacy.net> wrote:
the motor sees nice filtered DC with very little of the PWM leftover.
Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.
that it wasn't done right, but I'm still waiting to hear what was done wrong.
Given all the RoHS-related failures and the report that touching up solder
joints on the transistors fixes the problem, I am suspicious that it's a
soldering issue made worse by the extreme temperature cycling.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.
Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.
It's a cheap, reliable way of doing the job, if it's done right. It's clear
that it wasn't done right, but I'm still waiting to hear what was done wrong.
Given all the RoHS-related failures and the report that touching up solder
joints on the transistors fixes the problem, I am suspicious that it's a
soldering issue made worse by the extreme temperature cycling.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
J
jim beam
Guest
On 03/25/2013 06:59 AM, Scott Dorsey wrote:
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.
hot ticket items on the silicon fab agenda, and has been for some time.
there are some great pwm options out there, and for not a lot of money.
heat sink, i don't think there's any way that silicon is getting
sufficient cooling, and is clearly way up against its ceiling. whether
that's accident or design is another matter, but the bottom line is that
it's an issue that spans multiple different module manufacturers across
multiple continents with different internal designs - that reduces the
probability of it being rohs and slaps it firmly into the vehicle
manufacturer's lap.
--
fact check required
you don't want to integrate the output, merely rub the shoulders off the
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.
in this day and age, that's no longer true. motor control is one of the
hot ticket items on the silicon fab agenda, and has been for some time.
there are some great pwm options out there, and for not a lot of money.
you definitely have a point there, but given the size and shape of that
heat sink, i don't think there's any way that silicon is getting
sufficient cooling, and is clearly way up against its ceiling. whether
that's accident or design is another matter, but the bottom line is that
it's an issue that spans multiple different module manufacturers across
multiple continents with different internal designs - that reduces the
probability of it being rohs and slaps it firmly into the vehicle
manufacturer's lap.
--
fact check required
J
jim beam
Guest
On 03/24/2013 08:52 AM, amdx wrote:
--
fact check required
interesting.
--
fact check required