Operator`s manual

Badger II Power Supply Operator’s Manual
Rev. 05/11/2012 Mission Power Solutions [phone] [e-mail] Pg. 6
At start-up, inrush current is limited by a PTC thermistor. The PTC is shunted out shortly after initial power-up
by a DC bus voltage sense circuit driving a thyristor. After rectification, the input voltage is put through a boost
converter that keeps the AC input current sinusoidal and synchronized with the input AC voltage. The boost
converter delivers a regulated input to the hold-up capacitors and a high voltage backplane. The backplane sup-
plies power to the DC-DC converters that provide the desired low voltage, regulated outputs.
Voltage conversion is achieved by Vicor’s family of Zero-Current-Switching (ZCS) DC-DC converters. These
are forward converters in which the main switching element switches at zero current. This patented topology
has a number of unique attributes: low switching losses, high frequency operation (resulting in reduced size for
magnetics and capacitors), excellent line and load regulation, wide output adjustment range, low EMI/RFI
emission, and high efficiency.
At initial power-up, the Badger II outputs are disabled to limit the inrush current and to allow the DC bus po-
tential to settle out to the correct operating level. A low-power flyback converter operating with PWM current-
mode control converts the high voltage DC bus into regulated low voltage to power the internal housekeeping
circuits and DC cooling fans.
The internal housekeeping Vcc comes up within 1 second after the application of input power. Once the high
voltage bus is within operating limits, the AC Power OK signal changes its output to a TTL “1,” indicating the
input power is OK, and allows the power outputs to come up 15-30 ms later. An auxiliary Vcc output of 5 VDC
capable of sourcing up to 0.1 A is provided for peripheral use.
An output Enable/Disable function is provided by using an optocoupler to control Vicor’s DC-DC converters.
If the Enable/Disable control pin is pulled low, the optocoupler turns on and disables the output. The delay for
an output to come up when measured from release of the Enable/Disable pin is 5-10 ms. The General Shut-
down function controls all outputs simultaneously and works in a similar manner.
Power
Output
Line Filter
Rectifier
Soft Start
Circuit
Boost Converter
Output Card #1
Output Card #2
Output Card #3
PFC Control
Customer
Interface
E/D Control
Fan
Housekeeping
Power
Input
Current
Sample
Waveform
Sample
Enable/Disable Control
Power
Output
Power
Output
Figure 10. Badger II Architecture