volatge boosting(Mc34063a )

[soheil6818]

hi all!!!!
first i'll start with a TINY description of my project . a SOLENOID KICKER.
so i want a 160v momentary power source to fire the solenoid. .my question is how can i reach to this voltage? the possible reasponse is to discharge 3 ,2200uf, capasitors in series.(3 * 50v =150v)
my source is a 2A ,12v battery.im planing to use MC34063, to Step the 12v source up to 50v.
second question is : can itself charge 3 cap in 6sec? would it need an external current boosting?
how much current can MC34063 supply?
thanks

 

[enjunear]

hi all!!!!
first i'll start with a TINY description of my project . a SOLENOID KICKER.
so i want a 160v momentary power source to fire the solenoid. .my question is how can i reach to this voltage? the possible reasponse is to discharge 3 ,2200uf, capasitors in series.(3 * 50v =150v)
my source is a 2A ,12v battery.im planing to use MC34063, to Step the 12v source up to 50v.
second question is : can itself charge 3 cap in 6sec? would it need an external current boosting?
how much current can MC34063 supply?
thanks

You might want to go down another layer and think about the amount of energy you need to drive the solenoid. Your three 50V, 2200 uF caps will store ~2.75 Joules of energy (U) each, for a net of 8.25 J. If you know how much power is needed (over the activation time), then you can calculate the amount of energy that must be stored. Energy stored in an inductor = \[\int\]Power \[\mathrm{d}\]t, from t=0 to t=t, max. Knowing the required amount of energy, you can then figure out the amount of energy needed to be stored by your caps using U = 1/2*C*V^2 (joules).

See:
Energy Stored in an Inductor - HyperPhyics
and
Energy Stored in a Capacitor - HyperPhyics

As for current-handling of the MC34063, one example in the datasheet shows an output of 28V @ 175mA. That's a charge capability of 28V * 0.175A = 4.9 watts. Since 1 Joule = 1 Watt*second, to charge the three 50V 2200 uF caps (8.25 J), it'd take 8.25 J / 4.9 W = 8.25 W*s / 4.9 W = 1.68 seconds. You'd have to work up a circuit that can generate 50V from 12V, so that will impact your V/I output characteristic, which will change your maximum output power capability, which in turn will affect the charge-time.

The design equations for a step-up converter are on page 11 of the datasheet, so start there and try to work up a boost circuit. See page 6, Figure 10 for the current-boost circuit topologies. You'll have to determine how big of a BJT/FET you'd need to add to increase the peak switching current (Isw).