Vicor Corp.

Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715

HAM, High-Boost Harmonic Attenuation Module

Rev. 2.5

Page 4 of 10

Set your site on VICOR at vicorpower.com

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.

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 V375 DC-DC converters.

Above 180 Vac input, the output voltage linearly increases with

input voltage. At 230 Vac the delivered voltage will be

approximately 365 Vdc. 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.

Note:

Non-Isolated

Output

Gate In

Gate Out

ZCS

Boost

Converter

Inrush

& Short

Circuit

Protection

High Frequency

Control

Voltage

Waveform

Current

Sense

AC

Line

Control

& House-

keeping

Circuitry

Output Voltage

Module Enable

Power OK

DC

Out

Recti-

fier

Aux. Supply

+

–

NOTE: No input to output isolation.

Input Voltage

Rated Output Power

Output Voltage

400

450

500

550

600

650

700

85

250

300

350

400

375

425

325

275

95 105 115 125 135 145 155 165 175 185 195 205 215 225 235 245 255 265

derate output power 11 W/V for Vin <110 Vac

110

Figure 1 — HAM block diagram

Figure 2 — Input voltage and current wave forms, with and

without power factor correction

Without PFC

With PFC

Figure 3 — Output voltage and power rating versus input voltage

TECHNICAL DESCRIPTION