VICOR VI-HAM-MM, VI-HAM-IM, VI-HAM-EM, VI-HAM-CM Datasheet

12

Note:
Non-Isolate
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.

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/in

■ 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

3

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 zero­current 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
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 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 DC­DC converters powered by the HAM, will come
high and enable the DC-DC converters when the
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 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 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 HAM.
The 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.

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).

Figure 2 • VI-HAM Block Diagram

12

Outputs
VI-200
DC-DC
Converter(s)

Rectified Line

Module
Enable

DC
Output
of HAM

Power OK

AC
Mains
120V
RMS

Boost Voltage

195
Vdc

240
Vdc

Off at
195
Vdc

Off at
230
Vdc

230
Vdc

25 ms

10 ms

50 100 150 200 250

300

Output Voltage
as a Function
of Input Voltage

Vac

400 Vdc
350 Vdc
300 Vdc
250 Vdc
200 Vdc
150 Vdc
100 Vdc

50 Vdc

25

75 125

175 225

275

80 Vac

85 Vac

260 Vdc

152 Vac

Operating Region

250 Vac

264
Vac

46V
Boost

296

Vin x

2

1-800-735-6200

Figure 3 • Functional Timing Diagram

Active power factor correctors incorporate a
boost regulator which must operate over a range
of incoming AC line voltages. Conventionally,
the output voltage of the boost regulator is set
to a value greater than the maximum anticipated
peak value of the incoming AC line.

Vicor varies the output voltage of the HAM as
a function of incoming AC line voltage
(see Fig. 4, patent applied for). On a nominal
120Vac line the output voltage of the HAM is
260Vdc — well within the input operating
voltage range of standard Vicor converters.
As input line increases, so does the HAM
output voltage; at 220Vac the delivered voltage
will be about 350V. 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 unnecessarily
sacrificing operating efficiency.

Figure 4 • Input Voltage vs. Output Voltage

VI-HAM Protection Features

Overtemperature Shutdown

The HAM incorporates overtemperature
shut-down, and is designed to shut down when
the temperature of the baseplate exceeds
90–100°C. It is not safe to run the HAM for
extended periods above its maximum operating
temperature of 85°C.

Short Circuit Protection

The HAM contains a short circuit shutdown
function. Operation of this function does not
clear the input fuse and the output will resume
normal operation after removal of the short. A
small period of time may be required to allow
for cooling of an internal PTC. Overcurrent
protection is provided by the Vicor DC-DC
converters.

Output Overvoltage Protection

The HAM contains output overvoltage
protection. In the event the output voltage
exceeds approximately 420Vdc, the boost will
decrease to maintain 420Vdc on the output.
When the peak of the AC line exceeds 420V
(approximately 293Vac) the boost will have
been reduced to zero. Beyond this the protection
circuit will be enabled and the output voltage
will decrease.

Pin Function Description

• L1 and L2/N (VI-HAM):

These pins are to be connected to the AC mains
output of a suitable EMI/RFI filter (Vicor
P/N 07818 or equivalent). Do not connect an
X capacitor across these pins as power factor
correction will be slightly degraded.

• +IN, –IN (VI-HAMD, VI-BAMD):

These pins are connected to the output of the external
bridge rectifier.

• Gate Input (VI-HAM):

This pin disables the boost converter only. Rectified
line current may still be present on the output. This pin

does not provide the same function as the gate input
pin of VI-200/VI-J00 modules. The user should not

make any connection to this pin.

• Gate Input (VI-HAMD):

This pin serves as a rectified AC following pin for
power factor correction synchronization to line. This
connection must be made through the synchronization
diodes between the line filter and bridge rectifier (see
Fig. 10, page 84).

• Gate Input (VI-BAMD):

The Gate Input pin is an interface pin to the Gate Out
pin of a VI-HAM, VI-HAMD or VI-BAMD depending
on configuration. The user should not make any other
connection to this pin.

• Gate Output:

The Gate Output pin is an interface pin to BAMDs;
the user should not make any other connection to
this pin.

• +Output and -Output and Holdup Capacitor:

These outputs should be connected to the respective
inputs of Vicor DC/DC converters. In addition, an
external holdup capacitor of 1000 µF with a minimum
voltage rating of 450Vdc, is required across the
output for 16 ms ride through time at 600W (500 µF
for 300W, etc). Do not exceed 3000 µF of total

output capacitance. Lower values of capacitance may
be used for reduced holdup requirements, but not less
than 330 µF. Lower capacitance values may degrade
power factor specifications.

• Auxiliary Supply (A/S):

The VI-HAM and VI-BAMD contain an internal low
voltage output (A/S) that may be used to power
primary side logic. This output is 19-23Vdc,
referenced to -OUT, at 3 mA max. Do not overload or
short this output as the HAM will fail. A typical use for
A/S is to power an optical coupler that isolates the
Power OK signal.

18 kΩ, 1/4W

A/S
≤ 3mA

-OUT

"Power OK" Status
Low = OK

+ OUT

P/OK

– OUT

E/O
A/S

19 - 23V

+

–

Figure 5 • Auxiliary Supply (A/S)

• Power OK (P/OK)

P/OK is a monitor signal that indicates the status of the
AC mains and the DC output voltage of the HAM.
P/OK, during normal operation, is an active low
(see Fig. 6). In the event AC mains or DC output fails,
this pin goes to an open circuit state. P/OK is asserted
when the output bus voltage is within normal operating
range and 20-25 ms after DC-DC converters are
enabled by the Module Enable output of the HAM.

This provides sufficient time for the converters to turn
on and their outputs to stabilize prior to P/OK being
asserted. When the AC mains is removed and the
output of the HAM drops below 230V, P/OK goes to
an open circuit state. When the output voltage drops
below 195V the converters are disabled via Module
Enable. P/OK will provide power fail warning at least
1 ms prior to converter shutdown.

P/OK

D

LOGIC

S

G

-OUT

Figure 6 • Power OK (P/OK)

• Module Enable (E/O)

The Module Enable output is used to disable the
DC-DC converters until there is sufficient energy in
the holdup capacitor (240V) to support normal
operation, while limiting inrush current. Module
Enable must be connected to the Gate Input of all
driver DC-DC converters. It is not necessary to
connect this pin to boosters as they are controlled by
their respective driver. If the AC mains fail, Module
Enable goes low when the DC output of the HAM
drops below 195V. Failure to connect Module Enable
may result in the output of the HAM latching low
during turn-on.

E/O

LOGIC

D

S

G

-OUT

Figure 7 • Enable/Output (E/O)