Controlling a solenoid beyond on/off?

Eavesdropper over 13 years ago

How does one control a solenoid beyond turning it on and off?

PWM control? Power it, then scale back the current?

Any info on alternative ways to power a solenoid would be most appreciated.

Thanks.

Top Replies

DAB over 13 years ago +1

Hi E, TI just announced a new Solinoid controller this week. You might want to take a look at it for your application. DAB

0 Former Member over 13 years ago

You have pretty much answered your own question. You can do it by Pulse Width Modulation or since solenoids have a lower retention current than pull-in current you can do it by current fold back.

Most of the issues tend to be analog though.

Please take a look at the links below.

Pulse Width Modulation (PWM) and Relays

Hold-In Circuit - Solenoids
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Former Member over 13 years ago

If you have a variable power supply you can pull in the contactor and then reduce the voltage to see what will hold it in, then recreate this voltage with a pwm signal and a Mosfet.
simply:

required hold in voltage = PWM% x supply voltage

placing the Mosfet on the low side of the coil will allow you to run the pwm from a micro and use a higher supply voltage.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 DAB over 13 years ago

Hi E,

If you use a solenoid with varying pulse widths, you need to be very aware of the huge amount of heat and current you may have to deal with. You ware probably much better off using a stepper motor or synchro. A motor would use less current and provide you with much better control levels.
Plus, you greatly reduce the back EMF that a solenoid can generate when the magnetic field collapses.

Just a thought,
DAB
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Eavesdropper over 13 years ago in reply to Former Member

Chris & DAB,

Thank you for the info and thoughts.

I have to use a solenoid, it is part of a valve system. I just want a scheme to turn the solenoid on/off using the least amount of power.

I was hoping for a simple, tried and true, solution.

Keep the thoughts coming...

Thanks again.

E
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 DAB over 13 years ago in reply to Eavesdropper

Have you considered using a windlass type system where the solenoid could step through the valve turn to meet need between on and off. A second solenoid could flip the direction latch so you had full control for various on and off steps.

Just a thought.
DAB
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 DAB over 13 years ago

Hi E,

TI just announced a new Solinoid controller this week. You might want to take a look at it for your application.

DAB
Cancel
Vote Up +1 Vote Down

Sign in to reply

Verify Answer

Cancel
0 D_Hersey over 11 years ago

Are you using a bistable relay?
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 sanuzr over 11 years ago

Yes you are correct. You can use PWM to do the job for you. Using DRV102 from Texas is a good choice. I have used it and is fantastic.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel