[SOLVED] Using LED driver IC to Drive Proportional Solenoid Valve

Hello everyone,

I am using PWM to control a proportional solenoid valve(12 V,340mA) to control air flow rate. The control system is working but the coil of the solenoid is getting very hot. I want to reduce the heat generated in the coil.

After searching on the internet. I found that If I use PWM current control then I can reduce the heat loss in the coil. Here is an Application note of MAXIM which describes how to use LED driver to control Solenoid Valve.

My question is ..Can i Use any 12 V 350mA LED driver (with pwm dimming ) to control the solenoid (Inductive load with flyback diode). and will this reduce the heat loss??


Proportional Valve Datasheet

I think you can but run a test to see if and how it works. If the valve is designed to run proportionlly to driving current, maybe it will work directly or you may need to use a smoothing capacitor to prevent vibration.

Proportional solenoid valve means the force acting on the plunger will be proportional to the applied current through out the stroke length. It need constant current source to drive, You can use led driver for your valve, It is better if you get a current controlled driver.

Yes jiripolivka data sheet of the solenoid says ..opening of the valve is proportional to current flowing through it. I will test the circuit tomorrow and let you know how it goes.. thank you for reply.

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smijesh said:

Proportional solenoid valve means the force acting on the plunger will be proportional to the applied current through out the stroke length. It need constant current source to drive, You can use led driver for your valve, It is better if you get a current controlled driver.

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you are right .. my concern is heating of the coil.

YOu can use any method to control current which directly controls flow.

But the medium itself must provide the cooling.

SunnySkyguy said:

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But the medium itself must provide the cooling.

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If you see the data sheet of the solenoid the coil assembly is on the top of the flow opening and also the flow rate is below 15 LPM . so it is not dissipating the heat properly unless I provide a separate cooling fan.

Hi,

I found that If I use PWM current control then I can reduce the heat loss in the coil

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The solenoid needs constant current.
I can´t see a way to lower the coil (the solenoid coil) loss. It is always I * I * R.
You need the same coil current with and without PWM.

But you can lower the control circuit loss. Here PWM is a good way.


Klaus

When continuously energizing adjacent valves at the same time, ambient
temperature rises since the coil generates heat. Implement measures to exhaust
excess heat so that the temperature remains within the range of the table on the
right.

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330mA*12V=4W

THermal rise is a function of surface area and air turbulence surface velocity.
So perhaps radial fin heatsink and 35mm fan for continuous use.

PWM will not reduce heat as rms of average duty cycle current (squared) thru coil resiistance dissipates heat and regulates flow.

Pd=I² Rs

If PWM is too high frequency then force may be reduced in solenoid as impedance rises and current drops.

One thing to consider is that if the valve is usually most of the way open and only sometimes closed than you may be able to find a different valve that has reverse characteristics such that you apply current to close it rather than open it. For example, a door lock made with a solenoid would want to be a pull type solenoid so you only need to briefly apply current to open the door and most of the time its dissipating no power. Not sure if this is relevant to your application but figured its worth consideration.

KD494 said:

One thing to consider is that if the valve is usually most of the way open and only sometimes closed than you may be able to find a different valve that has reverse characteristics such that you apply current to close it rather than open it.

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Yes I understand your point ..But this is proportional control valve and it is normally closed. If I can get the normally open valve then I have to close it till the flow reaches its set point.