Battery Management of Electric and Hybrid Vehicles Pr. J.L. Lilien

1
Battery Management of Electric and Hybrid
VehiclesPr. J.L. Lilien PhD. student H. Yuan ,
University of Liège, BelgiumLilien_at_montefiore.ulg
.ac.be

• Vrev 0.043x I
• Ni-Cd 100 Ah, 6V
• (V in Volts if I in A)

Voltage vs time (s)

• Problems
• Ageing
• Large transient energy consumption different from
  continuous discharge
• Small current effects not the same as large
  current

• Why BMS ?
• To know ACTUAL free voltage
• Adapt current extraction to obtain needed power
• Help SOC evaluation

Reversible voltage vs SOC
Solutions by parameters spectroscopy in real
time 2 time constants model of V(t) V(t)
Vini RW.I Vrev1(1-e -t/t1) Vrev2(1-e -t/t2)
R W.I Vrev Vrev1 e -t/t1 Vrev2 e -t/t2
V0DOD Vrev1 e -t/t1 Vrev2 e -t/t2
Permanent revision of V0DOD R W Vrev and the
two time constants
Internal resistance vs SOC
Cd electrode Time constant vs SOC

• Lab and road tests with 20 Ni-Cd 100 Ah

Free voltage vs SOC (different discharge currents
40, 60, 80 (red) and 100 A (cyan))
Our hybrid cars (pre-proto and modified Lupo 3l
into hybrid (60 g CO2/100 km))
Voltage calculated and measured along urban cycle
ECE15
t1 250 s t2 7 s RW 3.2 mW Vrev0.0043xI