AVX High Power Capacitors for High Power Electronics - AVX

Catalogue AVX High Power Capacitors for High Power Electronics

Page

/ 34

/ 34

Text version of the page

CAPAFIM Products

Capacitor Design

/aM<

V_N DETERMINATION

The design is based upon the operating voltage V_w

where

Example:

You need:

C = 500 uF

DC voltage = 1850 V

f = 300 Hz

^Irms ⁼ ⁵⁰ ^A9amb = 50°C

Vr= V 2 x Irms/ (n f Cn)

According to the tables of values, you should find a capacitor with required capacitance C_n and voltage V_n (provided that Vn > Vw).

You must also verify that the working current and the ripple voltage can be accepted by the capacitor.

THERMAL DESIGN

Total losses are calculated as follows: P = Irms² (tg§o/Cn2rcf +Rs)

(tgSo = 3x10^-4 represents the dielectric losses of the polypropylene + rapeseed oil)

Calculate the hot-spot temperature:

9|HS =9amb +RthP

(Rth is the thermal resistance between hot-spot and ambient) (see the table value below)

Hot-spot temperature must be below 75°C.

If hot-spot temperature is higher, then chose another type

and start again the calculation.

According to data:

Vr = 150 V peak-to-peak V_w = 1850 + 150/2 = 1925 V

= capacitor type B V_n = 2000 V C = 507uF

^Irms < ^Imax ^Vr — ^Vmax

2100 2000 1900 1800 1700 1600 1500

Vn Vw Vdc

-1/f-

Thermal Calculation:

Total losses

P = 50²x(3x10^-4/(507x10^-6x2nx300)+3.49x10^-3) = 9.5W

The hot-spot temperature in this example is therefore: 9_HS = 50+1.24x9.5 = 61.8°C 9hs <75°C

= Part number DNCFM2K0B5076

EES