Hay
I want control the 400mA, 24V load using PWM
Which device is preferable for switching applications TRANSISTER or MOSFET?
Please suggest TRANSISTER or MOSFET for the above application
Regards
chandu
switching
Hay
I want control the 400mA, 24V load using PWM
Which device is preferable for switching applications TRANSISTER or MOSFET?
Please suggest TRANSISTER or MOSFET for the above application
Regards
chandu
You didn't say whether you're switching the high or low side or the frequency. I'll assue you're switching the low side as it's much easier.
BC548, BC337, IRL540.
I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.
Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.
switching
Thanks for the reply
I am controlling the 400mA, 24V proportional solenoid valve using PWM
I can generate any frequency from 100Hz to 14MHz using LPC2106
So what frequency range I can use for above application
What are the considerations for switching application?
Regards
chandu
It doesn't really matter what the frequency is. It needs to be high enough for the current to remain circulating in the solenoid when ther transistor is off an low enough to prevent switching losses from being excessive. I'd recommend about 100kHz but it really depends on the inductance of the coil.
I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.
Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.
switching
Hay
I am using Series SVP Proportioning Solenoid Valve from
http://www.dwyer-inst.com/PDF_files/SVP_iom.pdf
In the pdf they have not mentioned any information regarding the inductance & switching frequency
Presently I am using 1Kz PWM & switching transistor as TIP122,
TIP122 can useful for only 3KHz (lower switching applications)
Regards
chandu
use transistor , or optotransistor , but for the solonoid valve (its inductive load) it won't work properly...
my suggestion is thatgo for ssr's for switsching......
how would u generate 100Hz PWM pulse & what is ur clock frequency......
400mA ,24 V is it a dc?
hm:
Driving a proportional valve
Reading the datasheet of the valve, I think you should not feed it with a PWM signal but with a variable DC voltage. Because of the nature of the proportional valve, the PWM approach may bring to very poor linear control of the flow.Originally Posted by chandu13
I suggest you use the PWM output of the micro to feed a low-pass filter (active or passive) that drivers a power op-amp to drive the valve.
Here is a brief list of power opamp: LM675, OPA569, L165 ... but be sure to check the dissipation of the device and provide correct cooling.
I'd recommend a power MOSFET like the IRL540.
Keeping the frequency above 20kHz is a good idea as you won't be able to hear it.
I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.
Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.
switching
Thanks for the information
Please can you provide interfacing circuit between the LPC2106 and Proportional valve?
Shell I connect LPC2106 Port pin to the IRL540 with Rg, how to calculate the Rg value
For PWM generation a I am using LPC2106 PWM Registers, it have in built PWM hardware
PWMMR0=0x00003999; // base frequency register
PWMMR4=0x00001CCC; // Duty cycle register
PWMMR0=0x00003999; // 1KHz
PWMMR0=0x00001CCC; // 500Hz
PWMMR0=0x0000005C2; // 100Hz
Clock frequency = 14.7MHz
Regards
chandu
The Philips NXP microcontrollers are not that popular in among the hobbyist market. I've not seen alot of code or even a users group for them. Why not use something more popular like PIC or AVR microcontrollers? Either can do simple PWM valve control.
Mosfet (irl540)
Hay
I have tested proportional solenoid with TIP122 & 1KHz frequency
Across the load I am getting sufficient voltage but I am not getting the sufficient current to the solenoid
So now I have to use power MOSFET (IRL540) & frequency above 20kHz
How to interface LPC2106 with MOSFET (IRL540)
please provide me information information
Regards
nari
hi Chandu,
Why do you consider that the solenoid requires anywhere near a 20KHz frequency drive.?, that equates to a 25µSec half cycle pulse.
Just changing the drive frequency is not PWM control.
How accurately must you control the position of the valve.?
IMO the inductance of the solenoid winding is having an effect upon the solenoid current at those higher frequencies.
XL = 2 * Π * L * f
EDIT:
Does the prop valve have a spring return mechanism or does it require bi-directional PWM.?
Last edited by ericgibbs; 20th August 2008 at 01:06 PM.
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/
valve position
Thanks for the reply
The proportional valve require unidirectional PWM pulses
By varying the PWM duty cycle I have to control the valve position
I am using Proportioning Solenoid Valve from
http://www.dwyer-inst.com/PDF_files/SVP_iom.pdf
Regards
nari
hi nari,
I have looked at the pdf.
What you need to do is control the pulse width as well as the frequency.
Taking a very rough example:
Assume the 100% operating speed from closed to open was say, 1 sec
If you applied 24V, the 400mA would flow and the solenoid would fully open in 1 sec.
If you now applied 24V for 0.5sec the valve would reach its 50% open point before the current was shut off,
the valve would then start to close.
If now you repeatedly applied a short pulse of 24V the valve would held at the 50% open point.
By increasing or decreasing this 'holding' pulse width the valve could be held at any position.
The graph on the pdf is just a guide, you will have to experiment with the PWM timing to get it just right.
What I would do is to set up a variable freq 555 driving a variable delay monostable.
The output of the mono would drive a power FET, which would power the valve.
While varying the freq of the 555 and the delay of the mono, use a scope to get an indication of the range of the PWM.
Once you have these values you could then program a PIC.
Use the PIC's adc inputs and connect two pots, one for freq and the other for the PWM period. [use the on PIC PWM of course].
Does this help.?
Last edited by ericgibbs; 21st August 2008 at 08:53 AM.
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/
Hay
I am facing hystersis problem while testing proportional solenoid valve.
Solenoid valve rating is 0-24V & 400mA,I tested solenoid with variable DC power supply
When ever I am applying 0-24 v the valve is opening but the valve is not closing at the same voltage
Ex: Whenever I applied 16V(3.3) the valve is opened but it is closing at 5V(3.3)
(OPENING)
Volt(V) -> airflow (LPM)
9 -> 0
10 -> 0
11 -> 0
12 -> 0.5
13 -> 1.7
14 -> 2.8
15 -> 3.1
16 -> 3.3
17 -> 3.4
18 -> 3.4
maximun flow
(CLOSING)
volt(V) -> flow(LPM)
18 -> 3.4
17 -> 3.4
16 -> 3.3
15 -> 3.3
12 -> 3.3
7 -> 3.3
6 -> 3.3
5 -> 1.6
4 -> 0.8
3 -> 0
Regards
chandu
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