Back Emf

[chandu13]

Hai

I am facing BACK EMF problem in the proportional solenoid valve, am using 1N4007 diode across the load and 14KHZ PWM signal for swiching.
I am facing hystersis and Reputability problems with the BACK EMF
Please suggest methods to over come back emf problem with proportional solenoid valves

Regards
chandu

 

[Nigel Goodwin]

Why are you using 14KHz PWM?, it sounds rather high - and MUCH too high for a 1N4007.

 

[Leftyretro]

Hai

I am facing BACK EMF problem in the proportional solenoid valve, am using 1N4007 diode across the load and 14KHZ PWM signal for swiching.
I am facing hystersis and Reputability problems with the BACK EMF
Please suggest methods to over come back emf problem with proportional solenoid valves

Regards
chandu

I worked a lot with linear solenoid actuator controlled valves is the process control industry. I can't think of any I came across that used other then simple DC current control. While that doesn't mean the PWM could not be used I wonder why? If it's a power efficiency thing keep in mind that most of the designs I came across used a pretty small electrical solenoid and 'amplified' it's mechanical power by using pneumatic or hydraulic pilot relays, meaning that not a lot of electrical power was required, mostly just standard 4-20ma DC 'current loop'. Air or hydraulic power was the real power source for actually supplying the mechanical power required.

 

[Hero999]

Use a Schottky diode e.g MBRS360.

 

[Willbe]

. . .BACK EMF problem . . .

You mean e=-L(ΔI/ΔT)? Not the same thing.

 

[chandu13]

Lower frequency

Hi
Now am using 100Hz PWM signal to drive proportional solenoid valve with 1N4007 diode across the load
My circuit is working somewhat better compare to the higher frequencies and it has reduced the hystersis problam some what,
But proportional solenoid valve is creating some noise

Please suggest for industrial application, which is better

1.Higher frequency & fast switching diodes like MBRS360 Or
2.Lower frequency & normal switching diodes like 1N4007

regards
chandu

 

[Nigel Goodwin]

Stop jumping from extreme to extreme, pick a sensible PWM frequency, usually 1KHz to 3KHz is pretty common.

 

[chandu13]

Voltage+backEMF

hay

Please suggest suitable diodes for the rang of 1KHz to 3KHz PWM signal to reduce the back EMF in the proportinal solinide
Diodes well have normally 0.7v forward voltage, if back EMF is 0.6V how to nullify the back EMF
Ex: if I want flow rate for 5V I am getting flow rate for 5V+backEMF
Please suggest suitable circuits for to nullify the back EMF
This back EMF is creating a lot of problems in gas fuel control

Regards

chandu

 

[Nigel Goodwin]

Why do you think it's the back EMF?, hysteresis is a normal attribute of a coil, and is the standard example of it.

 

[Willbe]

Please suggest suitable diodes for the rang of 1KHz to 3KHz PWM signal to reduce the back EMF in the proportinal solinide

In order to spec. the diode we need to know steady state coil current, since the diode will see this current for an instant; what is the steady state coil current?

 

[Mephisto]

Proportional solenoid control circuit

Hi,

I need a some schematic about proportional solenoid control. If you have it, please, could you send to me a copy?

Thanks.

Mephisto.