Technical Description
The HAM (Figure 1) consists of a full-wave rectifier,
a high-frequency zero-current switching (ZCS) boost
converter, active inrush current limiting, short-circuit
protection, control and housekeeping circuitry.
The incoming AC line is rectified and fed to the boost
converter. The control circuitry varies the operating
frequency of the boost converter to maintain the output
voltage of the HAM above the peak of the incoming line,
while forcing the input current to follow the waveshape
and phase of the line voltage. The AC input current
follows the voltage waveform and a power factor better
than 0.99 is achieved. Operating efficiency of the boost
converter is optimized at any incoming line voltage by an
adaptive output voltage (Figure 3) control scheme.
AC
Line
Recti-
fier
ZCS
Boost
Converter
Current
Sense
Inrush
& Short
Circuit
Protection
+
DC
Out
–
Note:
Non-Isolated
Output
Voltage
Waveform
High Frequency
Control
Output Voltage
Control
Module Enable
& House-
keeping
Power OK
Circuitry
Aux. Supply
Gate In
Gate Out
NOTE: No input to output isolation.
Figure 1
— HAM Block Diagram
Oscilloscope photos showing input voltage and current
waveforms.
Figure 2a – Without power factor correction
Figure 2b – With power factor correction
Figure 2a
— Without PFC
Figure 2b
— With PFC
The output voltage of the HAM is a function of incoming
AC line voltage (Figure 3). On a nominal 115 Vac line,
the output voltage of the HAM is 280 Vdc — well within
the input operating voltage range of Vicor DC-DC
converters. Above 180 V input, the output voltage linearly
increases with input voltage. At 230 Vac the delivered
voltage will be aproximatly 365 V. For any given input
line voltage, the HAM maintains enough headroom
between the output voltage and peak input voltage to
ensure high quality active power factor correction
without sacrificing operating efficiency.
425
700
650
400
375
350
325
300
275
250
85
95 105 110 115 140 160 180 200 210 220 230 240 250 264
600
550
500
450
400
Input voltage
VRMs
Rated Output Power
Output Voltage
Figure 3
— Output voltage and power rating versus input voltage
Vicor Corp.
Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
HAM, Harmonic Attenuation Module
Rev. 1.5
Page 4 of 8
Set your site on VICOR at www.vicorpower.com
Output Voltage
Output Power
VICOR [ VICOR CORPORATION ]
