Saft evolion Technical Manual - page 19
20
IMD.
In general operating at or close to IMR risks activating the charge regulated mode. For all practical purposes, operating with IMR is
not recommended. However, for applications using only one installed Evolion and where cycling is infrequent (once per week or longer
interval), if operating with IMR, it should avoid the charge regulated mode since a re-charge current margin factor is used in the Evolion.
0.85 x IMR
. The default setting for this factorized IMR is 0.85 multiplied by the IMR. This factor (0.85) can be changed in each Evolion
using the Evolion Toolbox software. In operation, this factorized value of IMR. is available through the RS485/Modbus communication
bus of the Evolion. It is typically used as output current control parameter. If ever the output current of the power system ever
becomes equal to or above the 0.85 x IMR value, then the output charge current should be adjusted lower in order to avoid the charge
regulated mode.
0.75 x IMR
. This guideline of IMR is the recommended level of maximum charge current when operating without communication control
with the recifier power system. The maximum re-charge current setpoint of the power system or maximum installed rectification for
re-charge and load can be determined using this guideline in combination with the maximum (or minimum) anticipated application
temperature. For example, if the highest temperature anticipated is 60 ºC, the corresponding 0.75 x IMR value is approximately 25 Amps
per Evolion module. So it would follow that the maximum installed output power or the set point for the maximum re-charge current
would use this for the maximum value. In this case, the charge regulated mode should be avoided when operated in the anticipated
temperature range.
For the charge regulated mode, if the IMR is ever encountered by an Evolion module, it will automatically activate the charge regulated
mode of operation. In this mode, the current will decrease to approximately 4 Amps (with the set point voltage at 56 Vdc). The
re-charge time will be approximately 24 hours to reach a full state of charge if fully discharged. When the charge regulated mode
is active, the module will direct connect once every minute in order to check if the current is still too high. If it is, it returns to charge
regulated mode.
The maximum allowed re-charge current is a function of the module temperature. See Figure 10.
Figure 10. The maximum re-charge current of the Evolion
If the Evolion is connected at - 40ºC (- 40ºF), no charge will be accepted until the Evolion temperature increases. After connecting and
powering on, the heater will be activated ON (see chapter Internal heater). If the temperature is less than - 30ºC (- 20ºF), the module will
operate in forbidden charge mode until the temperature rises above - 30ºC (- 20ºF). After, charge current starts to be accepted.
When connecting several Evolions in parallel, the current sharing between branches will vary due to normal variations in the module’s
internal impedance, the module’s state of charge, the module’s temperature and the application conditions. To avoid the charge
regulated mode, make sure to right size the charger output or set the maximum charge current to never exceed 0.75 x IMR. At 0.75 x
IMR, it will sufficiently account for normal current sharing variations. See further details in chapter Massive paralleling.
For frequent cycling applications where several cycles are solicited from the Evolion each day, the maximum re-charge current must
be set in order to manage the thermal characteristics of the module. Use Table 1 as guide.
Module temperature (ºC)
(ºF)
IMR (Amps)
-40 -30 -20 -10 0 10 20 30 40 50 60 70
-40 -22 -4 14 32 50 68 86 104 122 140 158
50
45
40
35
30
25
20
15
10
5
0
Internal heater operation
0.75 x IMR
0.85 x IMR
IMR