Is it possible to control the duty cycle for a high voltage solenoid? The solenoid I wish to actuate: Tubular Push solenoid, S-29-200-H page 1, Magnetic Sensor Systems on a 10% duty cycle.
I would like to power the solenoid using a power source and just use the arduino to control the duty cycle.
Not really as solenoids are highly inductive and will generate lots of back emf. You'd probably be better off using the arduino to control the driver circuit connected to the correct solenoid voltage.
The duty cycle the data sheet refers to is the ratio of on to off to control overheating of the coil. For example, if you look at the first row of the data sheet ;
If you drive that particular solenoid with 5 volts you can energise it for as long as you like (100% duty cycle)
If you drive it with 16 volts then you can only energise it for a maximum of 90 seconds after which you must let it cool for 800 seconds (10% duty cycle)
This strange ratio comes about from the heating effect being proportional to I squared. Since 16 volts is driving 3 times the current, the heating effect ids 9 times as great so you must only use it for 1/9th of the time (all numbers in very loose terms)
Of course the arduino can control the duty cycle, if you run it through the right size driver circuit. (of course you can't just hook an output pin to the solenoid.)
What kind of cycle are you looking for. You want it to push something ever 1 second, and rest for 9 seconds? Or what?
I am looking for a very low duty cycle, something like 60ms on and 5s off.
Unfortunately my knowledge of electronics is lacking. How would the switching of the driver circuit be done with an arduino? Is there a specific component I would have to use such as an electronic/digital switch which is turned on and off using the PWM on the arduino?
I don't think the PWM command will work, since it changes at about 500HZ.
But you can easily do your own timing ckt, and just turn an output on and off at the times you want.
Check the example programs in the IDE (blink led, or blink without delay).
Get the program working with an led first, then when it looks good, just send it to the driver ckt.
for the driver ckt: Google something like "arduino solenoid driver circuit". Lots of detail there.
What you may need to do is run the solenoid at full power to pull the load in, then run it at a reduced power to hold it in without the solenoid overheating. You can try using PWM, with a mosfet to drive the solenoid and a flyback diode to catch the back emf. However, you may get heating in the core due to eddy currents, because the core is quite likely not laminated. If that is the case, there are some further options, such as:
Increase the PWM frequency and add a power inductor in series with the solenoid;
Add a 2nd mosfet that applies power to the solenoid via a series resistor.
OP stated
I am looking for a very low duty cycle, something like 60ms on and 5s off.
he only needs it held in for about 60ms. Then it should cool down nicely in the following 5 seconds.
PWM could not be use for this, but a basic blink sketch would be just right. (of course a driver to provide the high power to energise the solenoid).
Im not to worried about it overheating as the duty cycle will be very low, the 60ms on and 5s off is the worst case scenario. I have looked at driver circuits but most I find on the net is mostly for driving 12v solenoids and motors. As I mentioned my knowledge of elctronics is lacking and not all to sure how to go about the sircuit. Would it be similar to that of the 12v just with different component values or is it a bit more complicated than that?
pfrost:
Im not to worried about it overheating as the duty cycle will be very low, the 60ms on and 5s off is the worst case scenario. I have looked at driver circuits but most I find on the net is mostly for driving 12v solenoids and motors. As I mentioned my knowledge of elctronics is lacking and not all to sure how to go about the sircuit. Would it be similar to that of the 12v just with different component values or is it a bit more complicated than that?
What voltage solenoid do you plan to use? The one you linked to comes in lots of different voltages. The standard mosfet driver circuit such as this http://home.comcast.net/~wahconah98/circuits/flyback.png works with higher supply voltages, if you choose an appropriate mosfet and diode. btw I would reduce the 1K resistor in that circuit to 100 ohms.
Would be the 120V I assume. Need the 180 watts as shown in the performance data of 10%.
pfrost:
Would be the 120V I assume. Need the 180 watts as shown in the performance data of 10%.
Why do you assume 120V? Is it because you have a 120V mains supply, so you think generating 120VDC will be easiest?
You need to advise exactly which solenoid you intend to use and what voltage you intend to operate it at.
From there you will get sensible advise on what the limitations of use are.
For example, if you select a unit rated at 48 volts and operate it at 120 volts then you must limit duty to 10%; however if you select a unit rated at 120 volts you can run it indefinitely (duty of 100%)
I still feel you are failing to grasp the difference between the arduino PWM facility and the duty limitations imposed on operating devices at voltages above their designed rating.
What is your solenoid planned to push (or pull)? How far does it need to move? How hard is it to push?
If it is easy to push, use a small power solenoid, if it is hard to push, use a high power one.
jackrae:
You need to advise exactly which solenoid you intend to use and what voltage you intend to operate it at.
From there you will get sensible advise on what the limitations of use are.
For example, if you select a unit rated at 48 volts and operate it at 120 volts then you must limit duty to 10%; however if you select a unit rated at 120 volts you can run it indefinitely (duty of 100%)I still feel you are failing to grasp the difference between the arduino PWM facility and the duty limitations imposed on operating devices at voltages above their designed rating.
To confirm, the solenoid being used is the 24V, not the 120V as originally stated. To be able to apply a power of 180 watt I would require 7.5 amp if Im not mistaken? This should then give the force profile as shown on the graph of the 10% duty cycle.
When using the arduino to switch a driver circuit on and off what component would be required in the switching circuit which acts as the "switch" which is controlled by the arduino?
You may have missed my previous question.
What is your solenoid planned to push (or pull)? How far does it need to move? How hard is it to push?
If it is easy to push, use a small power solenoid, if it is hard to push, use a high power one.
You may have missed my previous question.
What is your solenoid planned to push (or pull)? How far does it need to move? How hard is it to push?
If it is easy to push, use a small power solenoid, if it is hard to push, use a high power one.
Is 60 ms enought time for all the mechanical motion to be accomplished?
The solenoid is used as a kicker which needs to kick a ball. The force needs to be large as the velocity at which the solenoid(including the mass of the kicker) needs to be a certain speed. Basically the kicker will strike the ball at a stroke of 40mm.
Ok, I have a better understanding now. You may have to tamper with the 60ms, when you get there. I don't know if you may need a bit more time or not.
You're still missing the point
If you want 180watts out of your proposed 24volt solenoid then you have to drive it with 65 volts.
The information is on the data table.
But - and it's a big but - you are proposing a pulse duration of only 60mS so rather than watts you need to be talking about energy viz joules. Then do some mechanical maths and work out how much energy is required to overcome the inertia of the ball to launch it at x metres/second.
@jackrae,
Glad you agree with me. I was beginning to think I was on the wrong track. I don't know how heave the ball is, or how far he needs to move it, but I am think 60ms is not enough. More like 300ms maybe.
