This document discusses energy management systems for advanced power systems in electric vehicles. It notes that using only batteries limits driving range and increases costs, while supercapacitors provide higher power density and longer life but lower energy density. An integrated control strategy is proposed that uses batteries as the main source with supercapacitors providing extra power during acceleration or braking to regenerate power. The strategy selects operating modes based on vehicle speed and power demands, distributing output from the battery and supercapacitor accordingly. Further work is suggested to simulate and optimize different control strategies, incorporate additional components like fuel cells, and evaluate limitations.

1. Special Topics in Advanced Power System

2. Need for energy management system
 When only battery is used as energy storage
battery management system is sufficient
Limitation: short driving range and high cost especially in city areas
 Supercapacitors:
comparatively lower energy density but high power density
longer life cycle
can provide high peak current during acceleration and can be recharged during regenerative braking
 Combined energy source
Traditional linear power distribution control strategy: poor stability
Rule based EMS: does not take into consideration the dynamic operating conditions
Logic threshold control strategy
Fuzzy control strategy
Optimization based EMS

3. Overview of Hybrid power system
Battery
Supercapacitor
Bi-directional
DC/DC converter
Energy
Management
system Load
DC Bus
Pload
Pbatt
PSC
SOCSC
duty cycle
acceleration signal,
speed signal & load
demand
ISCref

4. Proposed Integrated control strategy
 Integrated
Speed change and logic threshold control strategy
Operating mode selection based on logic threshold control strategy
● Driving modes
o Constant speed/low acceleration: Source only battery; PLoad = PBatt
o Starting/acceleration mode: Source Battery + Supercapacitor; PLoad = PBatt+ PSC
o Deceleration/Braking mode: Source Supercapacitor; PLoad = PSC
o In deceleration mode, when charging = max. limit of supercapacitor; PLoad = PR (Power consumed by brake resistance)
Distribution of output of the battery and the ultra capacitor according to the vehicle speed and power demand

5. Hybrid energy system equivalent circuit
Source [2]: Battery & ultra-capacity multi-energy system sketch map
Source [1]: Hybrid power equivalent circuit

6. EMS for
HEVs &
PHEVs
Rule-
based
EMS
Determinist
ic Rule-
based
Electrical
Assist
control
Thermostat
control
Fuzzy
Rule-
based
Convention
al Fuzzy
Adaptive
fuzzy
Predictive
fuzzy
Optimizatio
n Based
EMS
Global
Optimizatio
n based
Linear
programmi
ng
Dynamic
programing
Evolutionar
y Algorithm
Game
theory
Real-time
optimizatio
n based
Energy
conservati
on
minimizatio
n strategy
Predictive
control
models
Artificial
Intelligence
algorithms

7. Further work
 Simulate a MATLAB model with the hybrid power system incorporating various control strategies like
Energy conservation minimization strategy, predictive control method
 Comparison of control strategy to optimize operation
 Incorporate Battery management system, check for fuel cell integration
 Find out limitations of the different strategy

8. REFERENCES
 [1] ‘Research on Hybrid Power system of Electric vehicle and Energy management strategy’
 [2] ‘A Study of Energy Management System of Electric vehicles’
 [3] ‘Review on Energy Management Systems for Hybrid E Vehicles’