Problem with DC Motor Driver Pololu 18v25 with E-Stop which will deactivate the Power Supply upon E-Stop Disengaged

Thread Starter

calvintanct

Joined Aug 16, 2021
10
Hello All,

This is my first time here and hopefully someone can help me solve this problem
Motor Control Problem.pngI want to control 24V DC motor directionally using Pololu driver 18v25 https://www.pololu.com/product/2994
Above is my circuit diagram, I am using
  • 10A circuit breaker
  • SSR (Solid State Relays) with normally open (NO) and the coil is connected to the E-Stop, the coil operated at 5-36V and the contact is 0-220V 25A
  • E-Stop always supply 24V in normal condition
  • DC converter with 350W power 48V to 24V, Meanwell SD 350 C -24
  • Motor with rated current 5A
When I turn on the main power supply, everything runs well and there is no problem with the circuit.
Then, I engaged the E-Stop and cut off the power to Pololu 18V25.
When I disengage the E-Stop, the DC Converter suddenly powered off. The DC converter has a overcurrent and overtemperature limit feature.
I cannot turn on the DC converter again unless I cut off the main power supply, wait for a few seconds (15 seconds) and turn on again the main supply

I found few observations using my multimeter
  1. The DC Converter VO+ and VO- is connected using connectivity feature in Multimeter, I know that DC converter output is only an Transformer which means is just a inductor or coil of wires. I am not sure if this is normal.
  2. The SSR contacts cable is somehow connected even when it is powered off using connectivity feature
    1. I tried to unplug the wire and using the connectivity feature on the contact itself, it is not connected which leads me to
    2. Tried connectivity feature on the wire connected to the contacts which one comes from Circuit Breaker and another from DC Converter, which somehow is connected!
It makes me wonder, is there anything wrong with the circuit or my component?
I don't know where to start troubleshooting

Please help me!
Thank you!
 

LesJones

Joined Jan 8, 2017
3,523
The output of the DC to DC converter can not be just a transformer. (A transformer only works with AC.) It may be a transformer followed by a rectifier and capacitor and possibly over current detection. (The converter may also just be a switch mode regulator. If so it will not have a transformer but it will have an inductor.)
Does the DC to DC converter have a minimum output load rating ?
Does the problem occur if the Arduino has a PWM output set to low speed ? (As you do not show how the arduino is powered I am thinking that on a normal power on the Arduino will by outputting a low PWM duty cycle so the initial motor current will be lower than if the PWM signal is for a higher speed.)
Does the fault occur if the wire to the motor is disconnected ?

Les.
 

LowQCab

Joined Nov 6, 2012
1,189
Is the SSR a Triac Output ?,
sometimes these can do strange things,
an SSR with a MOSFET Output,
and "Zero-Volt-Switching" is the most trouble-free.

Is the SSR rated for AC & DC-Loads ? or AC-only-Loads ?

The Power-Supply is probably sensing some sort of Voltage-Spike during SSR turn-off.
And an additional Filter-Capacitor on its Output "may" solve the problem.
A ~100uf Electrolytic, and a 100nf Ceramic on the
Output will probably work if this is the problem,
both rated for ~50-Volts or higher.

Also, some Power-Supplies have a "Minimum-Load-Requirement",
although, the Spec-Sheet does state "0" to 14.6-Amps,
so this "probably" isn't a problem.
Does the Power-Supply-Output work with "no-Load" attached ?

It may be better to put the SSR -BEFORE- the Power-Supply.

If You are looking for an "instant-stop" for the Motor,
there are better methods than a SSR to do this.

The Motor-Control-Board may be capable of "Motor-Braking".
.
.
.
 

shortbus

Joined Sep 30, 2009
8,886
May be a dumb question but , why are you supplying the "18V25" with 24V? When you go to your link for it, there is a chart that says it's"Max nominal battery voltage is 18V". Located in block 1 of the chart.

Max nominal
battery voltage
1 G2 High-Power Motor Driver 18v25 18 V

from - https://www.pololu.com/product/2994
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
The output of the DC to DC converter can not be just a transformer. (A transformer only works with AC.) It may be a transformer followed by a rectifier and capacitor and possibly over current detection. (The converter may also just be a switch mode regulator. If so it will not have a transformer but it will have an inductor.)
Does the DC to DC converter have a minimum output load rating ?
Does the problem occur if the Arduino has a PWM output set to low speed ? (As you do not show how the arduino is powered I am thinking that on a normal power on the Arduino will by outputting a low PWM duty cycle so the initial motor current will be lower than if the PWM signal is for a higher speed.)
Does the fault occur if the wire to the motor is disconnected ?

Les.
1629124597446.png
Yes you are right about the rectifiers and filter. Across the V+ and V- there are only 200 ohm if I use my multimeter and it increase slowly, probably a capacitor. There is nothing about minimum output load rating and I think it is running properly even in low power.
the fault is still occur if the wire to the motor from driver disconnected, but if the wire from driver to breaker disconnected, it will be fine, so I am thinking might be the motor driver.
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
Is the SSR a Triac Output ?,
sometimes these can do strange things,
an SSR with a MOSFET Output,
and "Zero-Volt-Switching" is the most trouble-free.

Is the SSR rated for AC & DC-Loads ? or AC-only-Loads ?

The Power-Supply is probably sensing some sort of Voltage-Spike during SSR turn-off.
And an additional Filter-Capacitor on its Output "may" solve the problem.
A ~100uf Electrolytic, and a 100nf Ceramic on the
Output will probably work if this is the problem,
both rated for ~50-Volts or higher.

Also, some Power-Supplies have a "Minimum-Load-Requirement",
although, the Spec-Sheet does state "0" to 14.6-Amps,
so this "probably" isn't a problem.
Does the Power-Supply-Output work with "no-Load" attached ?

It may be better to put the SSR -BEFORE- the Power-Supply.

If You are looking for an "instant-stop" for the Motor,
there are better methods than a SSR to do this.

The Motor-Control-Board may be capable of "Motor-Braking".
.
.
.
Hello!
It is a MOSFET Trigerring with 220 VDC means it only for DC. I purposely bought it for DC. The SSR is only for DC.

I am sorry but the problem is on the DC converter, I put the title of this thread wrongly. the main supply is working fine.

and yes it is working without load, I know from the fan and led running with 24V across the V+ and - using multimeter.

Do you know any reliable motor control board?
I am using relay to make sure the power to the motor driver is totally off, so it will not run when the E-Stop pressed
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
May be a dumb question but , why are you supplying the "18V25" with 24V? When you go to your link for it, there is a chart that says it's"Max nominal battery voltage is 18V". Located in block 1 of the chart.

Max nominal
battery voltage
1 G2 High-Power Motor Driver 18v25 18 V

from - https://www.pololu.com/product/2994
Hello!
Yes because the battery max capacity normally much higher than 18V, so if I use battery, I cannot use 24V battery since full battery will reach around 25.6V. Since I am using DC DC converter, the output will be a constant 24V.
 

LowQCab

Joined Nov 6, 2012
1,189
The Motor-Controller will depend on what the purpose of this project is,
what is the Motor Powering ?

Why does the Speed and Direction of the Motor need to change ?

Do You need "Motor-Braking" ?

Do You have to have a Micro-Controller to control the Motor ?

Does it have to be micro-sized with all SMD-Components ?


.
.
.
 

LesJones

Joined Jan 8, 2017
3,523
I think LowQCab's suggestion of adding capacitors across the output of the DC to DC converter is a good first step. It could be the converter seeing a sudden step in output current is causing it to shut down. (It will probably have to charge capacitors on the input of the Pololu when the E-stop closes. ) Before doing this check that to output voltage of the DC to DC converter to make sure it has not gone too high when the E-stop is open. (If the 100 uF capacitor doed not fix the problem I would be tempted to try a 1000 uF capacitor.)

Les.
 

shortbus

Joined Sep 30, 2009
8,886
Since I am using DC DC converter, the output will be a constant 24V.
But you are still exceeding the recommended voltage. You are thinking the the absolute(30V) is a working voltage? Not the way I would approach this. And if this is a PM DC motor with brushes there will be spikes of voltage.
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
The Motor-Controller will depend on what the purpose of this project is,
what is the Motor Powering ?

Why does the Speed and Direction of the Motor need to change ?

Do You need "Motor-Braking" ?

Do You have to have a Micro-Controller to control the Motor ?

Does it have to be micro-sized with all SMD-Components ?


.
.
.
The motor is actually a linear actuator with 24V and rated 6 Amps. It only draw very little power.
Speed to finely adjust the extension length, while direction to extend and retract
Motor Brake is actually not needed, but I need to cut off all the power in case the controller signal from microcontroller gone wild for safety
The arduino is the microcontroller
size actually not an issue but since we are controlling small motor, it's better to be small too
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
I think LowQCab's suggestion of adding capacitors across the output of the DC to DC converter is a good first step. It could be the converter seeing a sudden step in output current is causing it to shut down. (It will probably have to charge capacitors on the input of the Pololu when the E-stop closes. ) Before doing this check that to output voltage of the DC to DC converter to make sure it has not gone too high when the E-stop is open. (If the 100 uF capacitor doed not fix the problem I would be tempted to try a 1000 uF capacitor.)

Les.
Okay I will take a look on this, the overcurrent protection take place when it is over 350 Watt, however my motor not even that powerful. and I have 24V 10A circuit breaker in place for sudden current spike (which never cut off the power). I am not sure if the current spike is really the reason. However I will still check the voltage and current to make sure. Thank you!
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
But you are still exceeding the recommended voltage. You are thinking the the absolute(30V) is a working voltage? Not the way I would approach this. And if this is a PM DC motor with brushes there will be spikes of voltage.
According to the data sheet, the recommended battery voltage is 18v but the rated voltage max is 25V, 30V is absolute max voltage. My DC converter has voltage tolerance based on load and line regulation of +-2%. However, thank you for your concern, I hope that I make the right design, because I found it hard to find reliable motor controller for this
 

LowQCab

Joined Nov 6, 2012
1,189
All too often, Motor Controllers seem to fall into 3 categories,
1)
Chinese / Hobbyist / questionable Specs and reliability / Super-Cheap / "toys",
2)
Serious / premium quality / USA made / expensive / works of Art,
3)
Purpose-designed from scratch.

You already have an over-rated, good quality, Power-Supply,
which, believe it or not, is sadly lacking in many DIY attempts.

The Circuit-Breaker and the SSR are really not necessary,
as any decent Motor-Controller will have an "Enable-Pin",
and your Power-Supply will do a fine job of Limiting-Current.

Reversing/Stopping, for Over-Current, or Physical-Contact faults, is easy to implement.

With the conservative Current-Levels being used,
it's not really necessary to use PWM-Speed-Control.

The only high-quality Brushed-Motor-Controllers that I am personally aware of
are for Hobbyist-Robotics, and/or, RC-Cars, Boats, Planes.
These are vaguely "similar" to what You have now,
but have large reputable Companies backing their performance,
and a very demanding user-base.

Some questions still left hanging ..........

What does your Linear-Actuator Actuate, and who, what, when, where, and how ?

What initiates extension and retraction of the Actuator ?

Do You need "Positional-Feedback" Control ?

And, (I have to ask this),
is this project meant to control an "Automatic-Chicken-Coop-Door" ?
.
.
.
 

Thread Starter

calvintanct

Joined Aug 16, 2021
10
All too often, Motor Controllers seem to fall into 3 categories,
1)
Chinese / Hobbyist / questionable Specs and reliability / Super-Cheap / "toys",
2)
Serious / premium quality / USA made / expensive / works of Art,
3)
Purpose-designed from scratch.

You already have an over-rated, good quality, Power-Supply,
which, believe it or not, is sadly lacking in many DIY attempts.

The Circuit-Breaker and the SSR are really not necessary,
as any decent Motor-Controller will have an "Enable-Pin",
and your Power-Supply will do a fine job of Limiting-Current.

Reversing/Stopping, for Over-Current, or Physical-Contact faults, is easy to implement.

With the conservative Current-Levels being used,
it's not really necessary to use PWM-Speed-Control.

The only high-quality Brushed-Motor-Controllers that I am personally aware of
are for Hobbyist-Robotics, and/or, RC-Cars, Boats, Planes.
These are vaguely "similar" to what You have now,
but have large reputable Companies backing their performance,
and a very demanding user-base.

Some questions still left hanging ..........

What does your Linear-Actuator Actuate, and who, what, when, where, and how ?

What initiates extension and retraction of the Actuator ?

Do You need "Positional-Feedback" Control ?

And, (I have to ask this),
is this project meant to control an "Automatic-Chicken-Coop-Door" ?
.
.
.
Hello LowQCab, thank you for supporting me until now.
I still think I need redundancy for this product which is actually will be a real product in the future, that's why I put the SSR for E-Stop and Circuit Breaker to protect the driver which does not have overcurrent protection, the DC converter has overcurrent but the limit is very high for the converter protection not for the pololu driver protection.
Thank you for your verification for the product quality!!!

My question remains the same with my first question. After I tried to check with oscilloscope, there is no voltage spike the moment it disengage from E-Stop. I don't think there is overcurrent because my circuit breaker also not reacting. But, my power supply is still turning off the moment EStop disengaged.
I need to know why this is happening. By the way I have also put the capacitor between the input of motor driver pololu, and it is still happening. Appreciate if anyone can answer this question, and provide any solution for this

For your other questions, the linear actuator will be controlled via arduino closed loop with position feedback from encoder reading. I am not sure if this answer is relevant to the problem that I am facing right now.
It is not for Auto Chicken Coop Door hahaha, thanks!
 

LowQCab

Joined Nov 6, 2012
1,189
"".........which is actually will be a real product in the future .......""

Do You have any idea how much the odds are against You in
actually having a commercial success from a "cool-idea" ?

The way that You are approaching this project is nothing like how
a "Real-World" version will ultimately be built if You expect it to actually
be commercially viable.

You'll need a custom designed Board that can be mass produced,
with the lowest parts-count possible,
with most parts doing 2 or 3 jobs simultaneously.
And preferably with no Micro-Controller that You will have to warranty.

It's astounding how many people come into these Forums with
a "World-Beater" idea that they've got to keep "Top-Secret" or somebody will steal
their idea and make the Billions that You rightfully deserve.

Bringing a new idea to Market is a cut-throat POLITICAL GAME,
"ideas" are a "dime-a-dozen" ..........
however,
You could carve-out a somewhat profitable niche manufacturing business
if You are really passionate about it.

Your Power-Supply can do a great job of protecting the entire device,
but that's not the Power-Supply that You will be using
in a successful new Commercial-Device.
So, the fact that You are having problems with your
"proof-of-concept" assemblage of parts is almost irrelevant.
You're just excited to see your idea come to life, which is great fun.
I know, I've done it at least 100 times.

Most likely, your device can be made with just a handful of analogue parts.

If You are willing to "divulge-Your-Secrets" and explain
what it is that your device is supposed to do,
I'm sure that You will get plenty of improvement ideas here
from some very experienced guys.

Present a Real-World scenario first, then ask for ideas based on the
actual environment/conditions that it will be expected to perform under.

Keep in mind that if this is going to be a successful commercial endeavor,
the cost of production needs to be approximately
10% of what You estimate people will pay for it at the retail-level.
At 30% You might just scrape-by at personal-survival-wages, but "keep-your-Day-Job".

Then there's the Mechanical-practicality of the device.
Knowing whether or not the Idea is actually practical comes only with experience.
.
.
.
 

LesJones

Joined Jan 8, 2017
3,523
The capacitor suggestion was for it to be directly across the output of the DC to DC converter. The reasoning behind it is for it to supply the fast current spike that may occur at the instant the SSR closes due to charging any input capacitors on the pololu. This current spike would be very short but may be enough to trip the over current circuit in the DC to DC converter. It would be too short to trip the circuit breaker.

Les.
 

Alec_t

Joined Sep 17, 2013
12,263
I don't think there is overcurrent because my circuit breaker also not reacting. But, my power supply is still turning off the moment EStop disengaged.
Your power supply overload capability is specified as 105%-135% of rated power. That brings the max Amps up to 14.6A x 1.35 = 19.7A before shut-down is triggered.
Your actuator motor current is rated 6A. If that is the normal running current then the motor stall/start-up current could well be ~five times that, i.e ~30A. Hence disengaging the E-stop would result in a start-up current surge and trigger the power supply to shut down. That might well occur before the circuit-breaker has time to react.
 

LesJones

Joined Jan 8, 2017
3,523
Hi Alec, I was originally thinking along the same lines so in post #2 I asked if the problem occurred with the wire to the motor disconnected and the TS said in post #5 that it did still occur with the wire to the motor disconnected.

Les.
 
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