vi-armb-c123 Vicor Corporation, vi-armb-c123 Datasheet - Page 9

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

Figure 18 — Converter ripple rejection vs. output voltage (typical)
Figure 17 — Ripple voltage vs. operating power and bus
capacitance, series combination of C1, C2 (see Fig. 10)
Another consideration in hold-up capacitor selection is their
ripple current rating. The capacitors’ rating must be higher
than the maximum operating ripple current. The approximate
operating ripple current (rms) is given by:
Calculated values of bus capacitance for various hold-up time,
ride-through time, and ripple voltage requirements are given
as a function of operating power level in Figures 15, 16, and
17, respectively.
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30
25
20
15
10
5
0
250
Where: P = operating power level
80
75
70
65
60
55
50
45
40
2
5
I rms = 2P/Vac
Vac = operating line voltage
500
1,100 μF
1,300 μF
15
Operating Power (W)
Output Voltage
750
1,600 μF
820 μF
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1000
30
680 μF (VI-ARM-x1)
2,200 μF
1250
(VI-ARMB-x2)
1500
50
(6)
ARM, Autoranging Rectifier Module
In this example, the output required at the point of load is 12
Vdc at 320 W. Therefore, the output power from the ARM
would be 375 W (assuming a converter efficiency of 85%). The
desired hold-up time is 9 ms over an input range of 90 to 264 Vac.
for a given power fail warning time and power level, and
shows that the total bus capacitance must be at least 820 µF.
Since two capacitors are used in series, each capacitor must
be at least 1,640 µF.
hold-up capacitor calculator is available on the Vicor website,
at vicorpower.com/hubcalc.
through time as a function of line voltage and output power,
and shows that at a nominal line of 115 Vac, ride-through
would be 68 ms. Ride-through time is a function of line
voltage.
Fig. 17 is used to determine ripple voltage as a function of
operating power and bus capacitance, and shows that the
ripple voltage across the hold-up capacitors will be 12 Vac.
rejection of the DC-DC converter and indicates a ripple
rejection of approximately 60 dB for a 12 Volt output. If the
ripple on the bus voltage is 12 Vac and the ripple rejection of
the converter is 60 dB, the output ripple of the converter due
to ripple on its input (primarily 120 Hz) will be 12 mV p-p.
Note that Maxi, Mini, Micro converters have greater ripple
rejection then either VI-200s or VI-J00s.
For more information about designing an autoranging AC
input power supply using the ARM and Vicor DC-DC
converter modules, contact Vicor Applications Engineering at
the nearest Vicor Technical Support Center (see back cover),
or send an E-mail to [e-mail].
The warning time is not dependent on line voltage. A
Fig. 15 is used to determine hold-up capacitance
Fig. 18 is used to determine the ripple
• • •
Figure 16 illustrates ride-
Rev. 3.8
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