Power for DC motor controller

B

Bob Engelhardt

Guest
I bought one of these 24v DC motor controllers:
https://www.ebay.com/itm/311703088756
It came with zero documentation. I found the basic connections on the
web, but nothing else.

My question here is: it takes 12-24v DC in and with just a variac and
bridge rectifier, it works. But would it work better with a regulated
supply? I'm guessing not because of its own big cap and PWM output.
But what do I know. If regulated would be better, in what way?

I don't want to just add caps because it will have very intermittent
duty and the fully-charged cap voltage would be way over the
controller's rated 24v.

Thanks,
Bob
 
In article <p7k6f701lt6@news4.newsguy.com>, BobEngelhardt@comcast.net
says...
I bought one of these 24v DC motor controllers:
https://www.ebay.com/itm/311703088756
It came with zero documentation. I found the basic connections on the
web, but nothing else.

My question here is: it takes 12-24v DC in and with just a variac and
bridge rectifier, it works. But would it work better with a regulated
supply? I'm guessing not because of its own big cap and PWM output.
But what do I know. If regulated would be better, in what way?

I don't want to just add caps because it will have very intermittent
duty and the fully-charged cap voltage would be way over the
controller's rated 24v.

Thanks,
Bob
Click to expand...

Usually the motor controller will work better. As the speed slows down
the PWM will give much more tork at the low RPMs.
 
On 3/5/2018 4:36 PM, Ralph Mowery wrote:
Usually the motor controller will work better. As the speed slows down
the PWM will give much more tork at the low RPMs.
Click to expand...

Thank you. It's the low speed that's most important in this case.
 
Bob Engelhardt wrote:

------------------------
I bought one of these 24v DC motor controllers:
https://www.ebay.com/itm/311703088756
It came with zero documentation. I found the basic connections on the
web, but nothing else.

My question here is: it takes 12-24v DC in and with just a variac and
bridge rectifier, it works. But would it work better with a regulated
supply? I'm guessing not because of its own big cap and PWM output.
But what do I know. If regulated would be better, in what way?

I don't want to just add caps because it will have very intermittent
duty and the fully-charged cap voltage would be way over the
controller's rated 24v.
Click to expand...

** The controller ideally should be supplied by a battery pack, a hefty
SMPS or a transformer based DC supply with about 30,000uF of smoothing.


..... Phil
 
On Mon, 05 Mar 2018 22:41:38 -0500, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 3/5/2018 4:36 PM, Ralph Mowery wrote:
Usually the motor controller will work better. As the speed slows down
the PWM will give much more tork at the low RPMs.


Thank you. It's the low speed that's most important in this case.
Click to expand...

The website says it is a PID controller. That's probably way more
sophisticated than you need or want. Do you have some tachometer
feedback signal? (and do they provide enough info so you can tune it
for your motor and load?)

With all the extra connections, and board mounted switches, looks like
it could be tricky to apply.
 
On 3/6/2018 1:23 AM, Phil Allison wrote:

** The controller ideally should be supplied by a battery pack, a hefty
SMPS or a transformer based DC supply with about 30,000uF of smoothing.


.... Phil
Click to expand...

Thanks ... that's 2 yea & 0 nay. I'm sure there's the parts in my
"collection" for a regulator.
 
On 3/6/2018 1:05 PM, default wrote:
The website says it is a PID controller. That's probably way more
sophisticated than you need or want. Do you have some tachometer
feedback signal? (and do they provide enough info so you can tune it
for your motor and load?)

With all the extra connections, and board mounted switches, looks like
it could be tricky to apply.
Click to expand...

"... enough info ...? Zero, zip, nada ... that's the problem.
 
On Wed, 07 Mar 2018 21:22:29 -0500, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 3/6/2018 1:05 PM, default wrote:

The website says it is a PID controller. That's probably way more
sophisticated than you need or want. Do you have some tachometer
feedback signal? (and do they provide enough info so you can tune it
for your motor and load?)

With all the extra connections, and board mounted switches, looks like
it could be tricky to apply.


"... enough info ...? Zero, zip, nada ... that's the problem.
Click to expand...

If it is a DC motor and you have a DC supply I'd go with a simple PWM.
You can't filter the output of those, it defeats the purpose of
chopping the power to control speed...

A better solution is a variable output switched mode power supply then
you can filter and send smooth DC to the motor and hang all the caps
you want on the output if you want a "stiff" power supply.

El cheapo PWM: https://tinyurl.com/y8sojspj

article on modding a SMPS for variable output:
https://tinyurl.com/hztw8o3

off-the-rack variable DC supplies:
https://tinyurl.com/y7q22rnw

I've got a cheap "battery eliminator" style PS that I got on Ebay for
~$20, it only outputs 3-12V in 1.5V increments at 5+ amps. It would
be child's play to make it continuously variable, just put a
potentiometer in place of the rotary switch. Then it would need a
meter and be less useful for what I use it for, so I haven't done it.
 
On 3/8/2018 6:17 AM, default wrote:

A better solution is a variable output switched mode power supply then
you can filter and send smooth DC to the motor and hang all the caps
you want on the output if you want a "stiff" power supply.

El cheapo PWM: https://tinyurl.com/y8sojspj

article on modding a SMPS for variable output:
https://tinyurl.com/hztw8o3

off-the-rack variable DC supplies:
https://tinyurl.com/y7q22rnw

I've got a cheap "battery eliminator" style PS that I got on Ebay for
~$20, it only outputs 3-12V in 1.5V increments at 5+ amps. It would
be child's play to make it continuously variable, just put a
potentiometer in place of the rotary switch. Then it would need a
meter and be less useful for what I use it for, so I haven't done it.
Click to expand...

Yeah, but ... I already HAVE the subject controller! I went for a more
sophisticated controller because of the extremely variable motor's run
conditions: it will run at low speed with no load, then a minor load
will be added, then a major load. I need the speed to stay more-or-less
constant through these changes & not have to be diddling with it.
 
On Fri, 09 Mar 2018 08:44:06 -0500, Bob Engelhardt
<BobEngelhardt@comcast.net> wrote:

On 3/8/2018 6:17 AM, default wrote:

A better solution is a variable output switched mode power supply then
you can filter and send smooth DC to the motor and hang all the caps
you want on the output if you want a "stiff" power supply.

El cheapo PWM: https://tinyurl.com/y8sojspj

article on modding a SMPS for variable output:
https://tinyurl.com/hztw8o3

off-the-rack variable DC supplies:
https://tinyurl.com/y7q22rnw

I've got a cheap "battery eliminator" style PS that I got on Ebay for
~$20, it only outputs 3-12V in 1.5V increments at 5+ amps. It would
be child's play to make it continuously variable, just put a
potentiometer in place of the rotary switch. Then it would need a
meter and be less useful for what I use it for, so I haven't done it.


Yeah, but ... I already HAVE the subject controller! I went for a more
sophisticated controller because of the extremely variable motor's run
conditions: it will run at low speed with no load, then a minor load
will be added, then a major load. I need the speed to stay more-or-less
constant through these changes & not have to be diddling with it.
Click to expand...

Understood. A PID controller can be tuned for load and the regulation
response can anticipate the power needed to maintain a set-point. To
do that it needs feedback so it knows what the RPM is, then it has to
be tuned to your system.

The scant information supplied does say it is for closed loop speed
control, and the info seems to suggest that can be an analog or
digital feedback. You don't mention if you have some form of
feedback.(?)

Short of finding the manufacturer and getting some more info, I
wouldn't know what to tell you.

I wouldn't be too crazy about PID control, any closed loop control
scheme should be able to maintain precise speed control.

Also you mention it will run at low speed. Geared motors are better
choices as a rule. 180 watts is ~1/4 HP or less.
 
On Monday, March 5, 2018 at 11:41:10 AM UTC-8, Bob Engelhardt wrote:
I bought one of these 24v DC motor controllers:
https://www.ebay.com/itm/311703088756
It came with zero documentation. I found the basic connections on the
web, but nothing else.

My question here is: it takes 12-24v DC in and with just a variac and
bridge rectifier, it works. But would it work better with a regulated
supply? I'm guessing not because of its own big cap and PWM output.
But what do I know. If regulated would be better, in what way?

I don't want to just add caps because it will have very intermittent
duty and the fully-charged cap voltage would be way over the
controller's rated 24v.

Thanks,
Bob
Click to expand...

Maybe you could Google the part number on that black square chip for a datasheet? Or did the seller sand that off?

Michael
 
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