EN1M11 Просмотр технического описания (PDF) - Vicor
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EN1M11 Datasheet PDF : 12 Pages
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Application Note
PRELIMINARY
The ENMods system provides an effective solution for the AC
front end of a power supply built with Vicor DC-DC converters.
This high performance power system building block satisfies a
broad spectrum of requirements and agency standards.
The ENMods system provides transient/surge immunity, harmonic
current attenuation and EMI filtering, in addition to all of the
power switching and control circuitry necessary for autoranging
rectification, inrush current limiting, and overvoltage protection.
Converter enable and status functions for orderly power up/down
control or sequencing are also provided. To complete the AC front
end configuration, the user only needs to add hold-up capacitors,
a simple EMI filter, and a few discrete components (Fig 1A).
Functional Description (FARM3, see Figures 9 & 10)
Power-Up Sequence.
1.1 Upon application of input power, the hold-up capacitors
begin to charge. The thermistor limits the charge current,
and the exponential time constant is determined by the
hold-up capacitor value and the thermistor cold resistance.
The slope (dv/dt) of the capacitor voltage versus time
approaches zero as the capacitors become charged to the
peak of the AC line voltage.
The switch that bypasses the inrush limiting PTC (positive
temperature coefficient) thermistor is open when power is
applied, as is the switch that engages the strap for voltage
doubling. In addition, the converter modules are disabled
via the Enable (EN) line, and Bus-OK (BOK) is high.
2.1 If the bus voltage is less than 200V as the slope nears
zero, the voltage doubler is activated, and the bus voltage
climbs exponentially to twice the peak line voltage.
If the bus voltage is greater than 200V, the doubler is
not activated.
3.1 If the bus voltage is greater than 235V as the slope
approaches zero, the inrush limiting thermistor is
bypassed. Below 235V, it is not bypassed.
4.1 The converters are enabled 50 milliseconds after the
thermistor bypass switch is closed.
5.1 Bus-OK is asserted after an additional 50 millisecond
delay to allow the converter outputs to settle within
specification.
Power-Down Sequence. When input power is turned off or
fails, the following sequence occurs as the bus voltage decays:
1.2 Bus-OK is deasserted when the bus voltage falls below
210Vdc.
2.2 The converters are disabled when the bus voltage falls
below 190Vdc. If power is reapplied after the converters
are disabled, the entire power-up sequence is repeated.
If a momentary power interruption occurs and power
is reestablished before the bus reaches the disable
threshold, the power-up sequence is not repeated,
i.e., the power conversion system “rides through”
the momentary interruption.
PTC
Thermistor
L
Strap
+Out
Strap
N
Microcontroller
–Out
SR
EN
BOK
Figure 9—Functional block diagram: FARM3 module
Power
Up
90–132V
AC Line
Output
Bus
(Vdc)
400
300
200
100
0 1.1
2.1
Strap
PTC
Thermistor
Bypass
Converter
Enable
Bus OK
3.1
4.1
50ms
5.1
50ms
Power
Down
2.2
1.2
Figure 10—Timing diagram: power-up/down sequence
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
ENMods System: FARM3 and MiniHAM
Set your site on VICOR at www.vicorpower.com
Rev. 1.3
Page 7 of 12
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