Week 9 Challenge
Model
Input of the model is Power demand(KW),which can be provided by the power train of the vehicle as load power demand to move vehicle.
The output of the model is the power request to fuel cell,ultracapacitor and battery to get power drain and charge during regeneration.
Energy Management Strategy
Positive Power
In propulsion subsystem(positive power) the power demand is tested for three components UC,Fuel cell and Battery based on their operating ranges using 'interval test' block as shown below
FC_test
UC_test
Battery_test
UC_fail condition
In this subsystem, the SOC of UC is checked as a FAIL condition using a switch block to give as output 1 and 0 for true condition.
The UC_test result is again checked with a switch block as it is TRUE(1) for above 55KW.
Both the signals are given to an AND block as this back up operation will set ON only both signals are TRUE.
Final output from AND is checked in a switch block, if output is 1 this positive power input is consider as battery backup source when Bat_SOC > Min. value as shown above as from outport 1.
UC & Battery fail condition
If both the SOC of UC and battery are less than their minimum values, in this stage the power drawn source is shifted to fuel cell.
This operation is implemented in this subsystem as shown below,
Negative Power
In Negative power (regeneration power) subsystem,
It was checked for UC_SOC > UC_Battery with the switch block.If the condition is true(1) then the negative power demand is passes as output from the switch 1.
Then if UC_SOC==Bat_SOC was checked, a half of the negative power is given as battery charge power and if fails the output from Switch 1 is given as battery charge power.
This battery charge power was checked in a switch 3 as if Bat_SOC >90% charging will not occur and if condition fails this batteery charge power from switch 2 is considered as final battery charging power
Power Demand (Input)
From this power demand signal we can see that there is positive power demand as propulsion power demand and negative power demand as power generated during regeneration to charge battery or ultracapacitor.
Result
Case 1:
UC_SOC = Bat_SOC
As both UC and Battery are having same SOC values the charging power are equally shared to UC and battery as we see from above plots.
Case 2:
UC_SOC>Bat_SOC
The power demand above 23KW is acheived by Fuel cell, above 55 KW is acheived by Ultracapacitor and 0-23KW from Battery source as seen from plots.
And also as UC_SOC is greater than Bat_SOC the charging power is shifted to battery to charge first rather than ultracapacitor.This can be verified as charging(Negative power) is occuring in Battery power plot alone and not in UC power plot.
Case 3:
UC_SOC<Bat_SOC
As Bat_SOC is greater than UC_SOC the charging power is shifted to Ultracapacitor to charge first rather than Battery .This can be verified as charging(Negative power) is occuring in UC power plot alone and not in battery power plot.