voltage controlled capacitor????

Discussion in 'The Projects Forum' started by onlyvinod56, Jan 6, 2010.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008

    not wasting the time,

    Iam designing a power factor correction circuit. (Not yet put on the PCB)
    Just paper work is going on.

    the phase angle between the voltage and current are measured in terms of a voltage.
    this voltage is compared with a preset (0 volts) to achieve 0 time difference (unity pf).

    my question is, how can i design a variable capacitance controlled by a voltage.

    any idea please...
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    How much capacitance do you need?
  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    Power factor correctors typically switch banks of capacitors in & out of circuit using large contactor-style relays.

    One setup uses multiple banks of capacitors, with each bank double the value of the last.

    If you imagine a setup with eg. six banks, values 1, 2, 4, 8, 16, 32 KVAR, it's possible to set any value from 0 to 63 KVAR by controlling the contactors with the equivalent six bit binary value.

    Use a binary counter and step the value up or down depending if the capacitance needs to increase or decrease.