SPECIAL CHARACTERISTICS AFFECTING THE SELECTION
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Figure 6. Battery voltage change as a function of State Of Charge (SOC)
The voltage window is important also from the process dynamics point of view. If we expect the
battery system to take energy (either discharge or charge), we create change in voltage of the
battery. The voltage controller needs to be capable to change the actual voltage of the battery in a
controlled way from full to empty value or from empty to full value. For example, if the battery is
wanted to be discharged in 30 s - 300V voltage window from 1000 Vdc - 700 Vdc it means roughly 10
V/s voltage change of rate. This is huge difference in comparison to for example case where
discharge time is longer, say 30 min resulting in 0,2 V/s. This way the SOC (State of Charge) behavior
is observed.
Below is a case where same sized of DC-power units are charged/discharged from the battery.
Figure 7. Battery string number effect on voltage change using the spring analogy
120
100
80
0
20
40
60
80
100
UDC [%]
SOC [%]
Charging of battery
Discharging of battery
1C
2C
3C
6C
9C
Summary of Contents for NX6
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