22 Circuit Description TB8100 Installation and Operation Manual
© Tait Electronics Limited June 2005
2.3 PMU
The TB8100 PMU provides stable, low-noise 28VDC outputs to power the
TB8100 BSS. The PMU is made up of a number of individual boards and
cards which comprise two main modules, the AC module and the DC
module. The standby power supply card and auxiliary power supply board
are optional. Figure 2.4 shows the configuration for an AC and DC PMU,
along with the main inputs and outputs for power and control signals.
The PMU is available in three main configurations:
■ AC PMU (AC input only)
■ DC PMU (DC input only)
■ AC and DC PMU (both AC and DC converters are fitted to allow both
AC and DC inputs).
AC Module The AC module accepts an input of 115/230VAC 50/60Hz nominal. The
input is fed via the PFC (power factor control) input stage to the HVDC
(high voltage DC) stage on the AC converter board. The HVDC circuitry
generates the final 28VDC outputs and provides galvanic isolation between
the mains input and DC output. The output stage on the AC converter
board provides a common output filter and current monitoring circuit
which is used by both AC and DC modules.
Each power stage is controlled by its own plug-in control card. The
microprocessor is also located on the HVDC control card. The
microprocessor is used by both the AC and DC modules and is fitted to all
PMU models.
The leaded high-power components are situated on the AC converter
board, while the plug-in cards have only SMD control components.
DC Module The DC module accepts an input of 12VDC, 24VDC or 48VDC nominal
(depending on the model). The input is fed through the DC input filter to
the input of the power stage on the DC converter board. This circuitry
provides PWM (pulse width modulation) conversion to produce the final
DC output. It also provides galvanic isolation, allowing the DC input to be
positive or negative ground. The final DC output is fed back to the output
stage on the AC convertor board.
The battery control card monitors the DC input voltage and prevents the
PMU from starting if an incorrect input voltage is applied. It also operates
as a fail-safe to prevent deep discharge of the battery, and provides
information to the microprocessor to allow the Service Kit software to
display information about the battery.
The DC control card controls the power stage of the DC converter. It also
provides protection from overload and short circuit conditions.
To Next Page
Loading...
Need help?
General
