PWM for solenoid control

Discussion in 'General Electronics Chat' started by saint_jay77, Jan 7, 2007.

  1. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    Hi,
    I am trying to make a solenoid driver circuit and am running into problems.
    I have inputs coming out of a device as such.
    I have a ground wire a 24 volt source and a 24V PWM signal from a low side switch. I am trying to drive a Mosfet driver IXYS IXDI404PI which can take input voltage of 0-18 volt.

    Problem is that i have a 24V PWM square signal coming from the low side switch which i would like to feed to the MOSFET driver which in turn would drive the FET, IRF530 gate and the drain source voltage will be 24 volts.

    Here is what i have tried: I have put a voltage divider 1.4K:1K at the 24 volt PWM signal but as soon as a connect to the mosfet driver it pulls the signal down and i do not get any driver signals for the driver. Do I have to use a capacitive divider???? This is not an AC signal!!

    SECOND ISSUE
    i gave up on the battle of driving with a 24V signal and used a freq generator to drive the MOSFET driver(IXDN404PI) when i an driving it I see that the output of the driver the positive edge of the square wave (PWM) is rounded. It almost looks like a capacitive transient.
    The output of the FET where the solenoid is connected has a great 80 volt spike with 24V input whenever it is transitioned from zero to 24V.

    I would really appreciate any help on this issues.
    Thanks...
    attached is a schematic
     
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  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    It appears that the schematic attachment did not make it into your posting.

    hgmjr
     
  3. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    http://ixdev.ixys.com/DataSheet/99018.pdf is the datasheet.

    If you want a non-inverting output, replace the IXDI404 with the IXDN404.
     
  4. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    i am not trying to invert signal but i am trying to find why my voltage divider cct doesnt work when connected to the input of ixdi404pi. actually it pulls it down. There is a cct in the work file attached....
     
  5. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Did you look over the datasheet?

    According to that datasheet and your description, the part you have listed is working properly.
     
  6. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    hi, i have looked at the datasheet but if i directly apply PWM 24V to the input pin the chip bows up after a while!!!!!!
     
  7. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    Hi, I got the PWM part switching with a 24 volt supply. I used the exiting 24V PWM signal to switch the ixdi404pi ixys driver and am switching the Power MOSFET gate of IRFB23N15D with the inverted signal from IXDI404PI. On the Drain source side I am using a 24V supply. 24V connected to the drain of the FET and on the having an inductive load on the source side. I presume it is called a high side switch.

    ISSUE: Now the problem is that the solenoid wont switch. It comes on for a fraction of a second and goes off immediately. I feel that the High side switching config that i have may not be working correctly because of the gate voltage. Oh another thing; I need to use high side switching because i need to preserve the duty cycle of the signal that i am feeding to the MOSFET switch.I do not want to use low side switching because the duty cycle changes. Please help. I am really stuck here.
    Thanking in advanced....

    RESOURCES
    http://www.irf.com/product-info/datasheets/data/irfs23n15d.pdf
    http://ixdev.ixys.com/DataSheet/99018.pdf
     
  8. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    The reason why the switch is not working correctly in the high side config is because the gate voltage needs to to be at least 12 volt higher than the source voltage for the Mosfet to be on an ON state. The problem i face now is that i have to find a way to decrease my drain source voltage inorder for it to switch properly. The voltage source at the drain is 24 volts and this will be see across the load between souce and ground. So the voltage i need to drive the N MOSFET with should be around 36 volts. Now the spec for the driver is that it can only drive up to 32 volts. In this case it would be sensible to reduce the drain supply voltage so that a lower voltage is seen across the load which means i need a voltage of 12 volts to drive the solenoid for the switch to work correctly.
    If this sounds OK please comment.
    Thanks....
     
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