# Current Required To Charge A Capacitor

## Recommended Posts

Hello Wizards,

I have got a requirement where by I want to charge a capacitor to 2000V in 30mSec or less. The capacitance value is 190uFD. I dont know how to calculate current required to charge this capacitor within this time and how can I check it using a controller?

Regards

Shree

##### Share on other sites
Hello Wizards,

I have got a requirement where by I want to charge a capacitor to 2000V in 30mSec or less. The capacitance value is 190uFD. I dont know how to calculate current required to charge this capacitor within this time and how can I check it using a controller?

Regards

Shree

Shree,

What you need is a capacitor charging supply and a pretty large one if you really mean 190uF, 2000V and 30mS.

These are often resonant mode switching supplies with or without a PFC front end and are normally rated for peak power.

Designing one of these for the performance you require is not a trivial task.

The stored energy for your capacitor is 1/2C*V^2 or 380 Joules at 2000V. This in itself is not particularly large but charging in 30mS is not easy and requires high power electronics.

The required peak power rating of the charger in J/S is (0.5 * Capacitance (F) * Charge Voltage * Power Supply Voltage Rating) / Charge Time (S)

In this case if we assume that the power supply is rated at the required capacitor voltage then

Ppeak = (0.5 * 190*10-6 * 2000 * 2000) / 30mS = 12666J/S

The peak charging current is twice that of an equivalently rated DC power supply so

Icharge = (2 * Ppeak) / Vrated = (2 * 12666) / 2000 = 12.66A

or alternatively Icharge = (Capacitance * Vcharge) / Charge Time = (190*10-6 * 2000) / 30*10-3 = 12.66A

As for monitoring the current, hall effect sensors are often used. Check out www.lem.com/

I hope this helps

Regards

davidb

##### Share on other sites

Hello David, Thanks a lot for your reply. Atleast I know now what direction I must proceed!

Regards

Shree

##### Share on other sites

DANGER! Risk of DEATH

The energy stored in that capacitor will cause death to anyone who touches it, are you sure you are up to the task. The chargeing current is only one of several concerns, how are you going to discharge it? 380 Joules is a lot of energy, more than in some defibulators!

##### Share on other sites

Thanks for the Caution!

Would keep that in mind

Regards

Shree

## Join the conversation

You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.