vi-armb-c123 Vicor Corporation, vi-armb-c123 Datasheet - Page 8

• Manufacturer Part Number: vi-armb-c123
• Description: Autoranging Rectifier Modules Up To 1500 Watts
• Manufacturer: Vicor Corporation

Figure 14 — Hold-up time
The power fail warning time (Δt) is defined as the interval
between (B OK) and converter shutdown (EN) as illustrated in
Fig. 12. The Bus-OK and Enable thresholds are 205 V and
190 V, respectively. A simplified relationship between power
fail warning time, operating power, and bus capacitance is
obtained by inserting these constants:
It should be noted that the series combination (C1, C2, Fig. 10)
requires each capacitor to be twice the calculated value,
but the required voltage rating is reduced to 200 V.
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.
For example, a converter whose output is 15 V and nominal
input is 300 V will provide 56 dB ripple rejection, i.e., 10 V p-p
of input ripple will produce 15 mV p-p of output ripple. (See
Fig. 18) 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. 14) of
the ripple, respectively. The capacitors must hold up the bus
voltage for the time interval (Δt) between peaks of the rectified
line as given by:
The approximate conduction angle is given by:
Vicor Corp. Tel: [phone] Fax: [phone]
Where:
C = 2PΔt / (205
C = 2PΔt / (5,925)
Δt = (π – θ) / 2πf
f = line frequency
θ = rectifier conduction angle
θ = Cos
Ripple (V p-p)
-1
1
V
and V
2
/V
1
2
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2
– 190
are the instantaneous
2
π – θ
)
θ
(4)
(5)
Power Fail
ARM, Autoranging Rectifier Module
Ride-Through Time
Figure 15 — Power fail warning time vs. operating power and
total bus capacitance, series combination of C1, C2 (Fig. 10)
Figure 16 — Ride-through time vs. operating power
Hold-up Time
40
35
30
25
20
15
10
100
90
80
70
60
50
40
30
20
10
5
0
250
0
250
500
500
Bus OK
1,100 μF
1,300 μF
Operating Power (W)
Power Fail
Operating Power (W)
Warning
750
750
1,600 μF
820 μF
Shut down
Converter
1000
1000
capacitance
Rev. 3.8
820 μF
680 μF (VI-ARM-x1)
Total
2,200 μF
90 Vac
1250
190 V
254 V
205 V
1250
(VI-ARMB-x2)
115 Vac
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1500
1500