VI-ARM-C11 VICOR [Vicor Corporation], VI-ARM-C11 Datasheet - Page 8

• Manufacturer Part Number: VI-ARM-C11
• Description: Autoranging Rectifier Modules Up to 1500 Watts
• Manufacturer: VICOR [Vicor Corporation]

Vicor Corp. Tel: [phone] Fax: [phone]
Application Note, continued
Figure 12—Hold-up time
The holdup time (∆t) is defined as the interval between power
fail warning (B OK) and converter shutdown (EN) as illustrated
in Fig. 12. The Bus-OK and Enable thresholds are 205V and
185V, respectively. A simplified relationship between hold-up
time, operating power, and bus capacitance is obtained by
inserting these constants:
It should be noted that the series combination (C1, C2, Fig. 8)
requires each capacitor to be twice the calculated value,
but the required voltage rating is reduced to 200V.
Allowable ripple voltage on the bus (or ripple current in the
capacitors) may define the capacitance requirement.
Consideration should be given to converter ripple rejection and
resulting output ripple voltage. The ripple rejection (R) of many
Vicor converters is specified as a function of the input/output
voltage ratio:
For example, a converter whose output is 15V and nominal
input is 300V will provide 56dB ripple rejection, i.e., 10V p-p
of input ripple will produce 15mV p-p of output ripple. (See
Fig. 16) Equation 3 is again used to determine the required
capacitance. In this case, V
values of bus voltage at the peaks and valleys (see Fig. 12) of
the ripple, respectively. The capacitors must hold up the bus
voltage for the time interval (∆t) between peaks of the rectified
line as given by:
The approximate conduction angle is given by:
Ripple (V p-p)
Where:
π – θ
∆t = (π – θ) / 2πf
C = 2P∆t / (205
C = 2P∆t / (7,800)
R = 30 + 20log(Vin / Vout)
θ = rectifier conduction angle
θ = Cos
f = line frequency
θ
-1
1
V
and V
Power
2
Fail
Set your site on VICOR at www.vicorpower.com
/V
1
Ride-Thru Time
Hold-up Time
2
2
– 185
are the instantaneous
2
)
B OK
Power Fail
Warning
Shutdown
Converter
254V
205V
185V
(4)
(5)
(6)
ARM, Autoranging Rectifier Module
Figure 15—Ripple voltage vs. operating power and bus
capacitance, series combination of C1, C2 (see Fig. 8)
Figure 14—Ride-through time vs. operating power
Figure 13—Hold-up time vs. operating power and total bus
capacitance, series combination of C1, C2 (Fig. 8)
100
40
35
30
25
20
15
10
90
80
70
60
50
40
30
20
10
30
25
20
15
10
5
0
250
0
250
5
0
250
500
500
500
Operating Power (W)
Operating Power (W)
Operating Power (W)
1100µF
1300µF
1100µF
1300µF
750
750
750
1600µF
820µF
1600µF
820µF
1000
1000
1000
capacitance
Rev. 2.4
820µF
Total
90Vac
2200µF
680µF
2200µF
680µF (Ver. 12)
1250
1250
1250
(Arm-1)
(Arm-2)
(Ver. 22)
115Vac
Page 8 of 12
1500
1500
1500