VI-HAM™, VE-HAM™

Rev 2.7

Page 4 of 10

08/2017

VxHAMxL

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.

The output voltage of the HAM is a function of incoming AC line

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.

InputVoltage

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 11W/V for V

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