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PSL Projects : Development of an Automatic Energy Recovery
System for Partially-Spent Batteries
This work is to study the feasibility to reclaim and
consolidate energy from partially-spent batteries (primary or secondary) into
secondary cells to minimize daily battery load carried by Marine squads and to
develop a prototype automatic battery energy recovery system in the laboratory.
The system will allow a soldier to connect any combination of
primary and secondary batteries together and it will recover (at appropriate
rates, considering urgency and energy efficiency) the energy from partially
depleted primary batteries and consolidate it into one or more secondary
batteries. An objective will be to make this process fully automatic so that no
knowledge is required on the part of the user. (But it may be desirable to allow
the user to select options regarding urgency or how to allocate the recovered
energy.) The energy recovery system will also be capable of acting as a
substitute power source for any one (or possible more) items of equipment,
aggregating the power available from several partially depleted batteries so
that it becomes sufficient to power any item of equipment in the soldier
inventory.
The approach used in this study is summarized as follows.
o Develop algorithms to optimize the number of primary and secondary batteries
o Develop adaptive battery discharging algorithms
o Develop automatic battery identification algorithms and adaptive battery
charging algorithms
o Develop floating bus voltage algorithms
o Develop various battery models and system model
o Design control strategies for power converters
o Perform system simulation in the Virtual Test Bed environment
o Validate the concept on real hardware
The system under study comprises five individual, identical
charging/discharging channels and an integrated controller, as shown in Figure
1. Each channel consists of a battery pack in series with a bi-directional dc/dc
converter. The power can flow through the power converter in both directions,
and then the battery can be charged or discharged. The users can choose between
charging and discharging their battery by setting the controller. The high
voltage side of each power converter is connected to the same voltage bus, and
then all power converters have the same voltage at the high voltage side. The
power converters control the charging/discharging currents of each battery, and
allocate the available power among the batteries. The controller is used to
coordinate these power converters. The control system is responsible for
managing the discharging process, regulating the bus voltage, automatically
selecting the secondary batteries to be charged, and limiting the charging
currents/voltages.
Figure 1. Block diagram of the proposed automatic energy recovery system for
partially-spent batteries.
Figure 2 shows a virtual prototype of the automatic energy
recovery system for partially-spent batteries that is built in the Virtual Test
Bed environment. Figures 3 through 5 show the voltages, currents and states of
charge of the batteries, respectively.
Figure 2. VTB schematic view of the automatic energy recovery system for partially-spent batteries.
Figure 3. Voltage of the batteries and the bus.
Figure 4. Currents from the batteries.
Figure 5. States of charge of the batteries.
Figure 6 shows an image of the PCB layout of the automatic energy recovery system for partially-spent batteries.
Figure 6. PCB layout of the automatic energy recovery system
