VI-HAM-EM Datasheet, PDF (1/6 Pages) Vicor Corporation – Harmonic Attenuator Modules

12 ^{1-800-735-6200}
VI-HAM
Harmonic Attenuator
Modules
Features
■ Unity Power Factor
■ Safety Agency Approvals:
UL, CSA, TÜV, BABT
■ Meets IEC 6100-3-2 for Line
Current Harmonic Content
■ Reduces Peak and RMS Line
Currents
■ Universal Input: 85-264Vac:
50/60 Hz
■ Up to 600W of Power
■ Power Density Up to100W/in³
■ Adaptive Output Voltage Control
■ Short-Circuit Protection
■ Input Surge Current Limiting
■ Converter Enable
■ Power OK Output
■ Size: 4.6" x 2.4" x 0.5"
(116,8mm x 61,0mm x 12,7mm)
■ Efficiency: 90-94% Typical
■ CE Marked
Unity Power Factor
Conventional capacitive-input front ends draw
energy from the AC line in short bursts of current
at the peaks of the line voltage waveform. These
current bursts are characterized by high peak
currents and high harmonic content. The effect of
the distorted line current can be appreciated by
measuring the rms line current drawn by a
conventional front end: the product of the
measured rms current and the rms line voltage —
the "apparent power" being delivered by the line
— will be significantly greater (typically 1.6X)
than the DC power delivered by the front end.
The "extra" rms current at the input is circulating
harmonic currents which deliver no power to the
load but which flow in the delivery system and
contribute to losses. Only the fundamental
component of the line current contributes to "real"
power flow. Power factor — the ratio of "real" to
"apparent" power — is a measure of the
effectiveness with which an AC load can extract
usable power from an AC source.
The VI-HAM (see Fig. 2) consists of a
full-wave rectifier, a proprietary high-frequency zero-
current switching (ZCS) boost regulator (patents
applied for), active inrush, short-circuit protection,
control and housekeeping circuitry. The incoming
AC line is rectified and fed to the ZCS boost
converter. The control circuitry varies the operating
frequency of the ZCS boost converter so as to
simultaneously maintain the output voltage of the
VI-HAM at a DC voltage value above the peak of
the incoming line, while forcing the input current
to the ZCS converter to follow the waveshape of
the rectified line. By this means, the AC input
current follows the AC voltage waveform and a
power factor better than 0.99 is achieved.
Operating efficiency of the ZCS boost converter is
optimized at any incoming line voltage by a
patented adaptive output voltage control scheme.
The VI-HAM also includes active circuitry which
controls inrush currents when power is applied
and active short circuit protection circuitry —
features not normally found in conventional power
factor correctors.
Housekeeping circuitry provides two signals of
use to the system designer (see Fig. 2): Module
Enable and Power OK. Referencing the timing
diagram (see Fig. 3), the Module Enable signal,
which is connected to the Gate In inputs of the
Vicor DC-DC converters powered by the
VI-HAM, will come high and enable the DC-DC
converters when the VI-HAM output voltage
exceeds 240Vdc. The DC-DC converter voltage
outputs will be up approximately 10 ms after
Module Enable goes high. Typically, 20 ms after
Module Enable goes high the VI-HAM Power OK
signal, which can be used by the system designer
to enable circuitry powered by the DC-DC
converter modules, goes low. On loss of power or
brownout, the Power OK signal will go high when
the VI-HAM DC output voltage drops below
230V, signaling an impending loss of input power
to the converter modules. When the DC output
dips below 195V, the Module Enable signal will
toggle low, disabling the converter modules and
unloading the VI-HAM. The VI-HAM will
provide at least 16 ms of ride-through or holdup
time, and at least 5 ms of AC fail warning time
with a 1000 µF output capacitor.
Figure 1a.
AC
Recti-
Line
fier
Voltage
Waveform
ZCS
Boost
Converter
Inrush
& Short
Circuit
Protection
+
DC
Out
–
Current
Sense
Control
& House-
keeping
Circuitry
High Frequency
Control
Output Voltage
Module Enable
Power OK
Note:
Non-Isolate
Output
Figure 1b.
Above: Oscilloscope photos showing input
voltage and current without power factor
correction (A) and with power factor correction
as provided by the VI-HAM (B).
Gate In
Gate Out
Aux. Supply
NOTE: No input to output isolation.
Figure 2 • VI-HAM Block Diagram
Vicor Corp. Tel: [phone] Fax: [phone]
HAM, Harmonic Attenuator Module
Set your site on VICOR at www.vicorpower.com
Rev. 1.1
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