ABSTRACT:
This paper presents a two stage battery charger for plug-in
electric vehicles (PEV) based on half-bridge LLC series resonant converter
(SRC) operating at resonance frequency. The first stage is power factor
correction (PFC) stage comprising of boost converter topology using hysteresis
band control of inductor current. The PFC stage reduces the total harmonic distortion
(THD) of the line current for achieving high power factor and regulates the
voltage to follow the battery voltage at DC link capacitor. The input of the
boost converter is a single phase 50 Hz, 220V AC from grid. At the second
stage, a half bridge LLC-SRC is used for constant-current, constant-voltage (CC-CV)
based battery charging and for providing galvanic isolation. The resonant
converter is designed to operate around resonance frequency to have maximum
efficiency and low turnoff current of power switches to reduce switching
losses. The circuit is simulated using MATLAB Simulink with 1.5 Kw maximum
output power. Simulation results show that the PFC stage achieves THD less than 0.07% and high
power factor value as 0.9976. The DC/DC
stage meets all the CC-CV charging requirements of the battery over wide
voltage range 320V—420V for depleted to fully charged battery.
KEYWORDS:
1.
LLC Resonant
converter
2.
PEV battery
charger
3.
PFC
4.
Hysteresis
band control
5.
FHA
SOFTWARE:
MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.1.
Typical power architecture of a battery charger.
CIRCUIT DIAGRAM:
Fig.
2. Schematic of the proposed battery charger.
EXPERIMENTAL RESULTS:
Fig.
3. Boost inductor current for a half cycle of input voltage.
Fig.
4. AC voltage and current after power factor correction.
Fig.
5. LLC-SRC operating at key point A (V0 = 320V, and I0 = 3.57A).
Fig.
6. LLC-SRC operating at key point B (V0 = 360V, and I0 = 3.57A).
Fig.
7. LLC-SRC operating at key point C (V0 = 420V, and I0 = 3.57A).
Fig.
8. LLC-SRC operating at key point D (V0 = 420V, and I0 = 0.25A).
CONCLUSION:
In
this paper, a 1.5 kW PEV battery charger with emphasis on the design of LLC-SRC
for DC-DC stage of the battery charger is presented. A method for improvement
in the power factor with boost converter
is presented using hysteresis current control to keep line input voltage and
current in phase using phase shift in
inductor current. Simulation results show that the PFC stage achieves minimum
THD as 0.07% and a power factor of 0.9976 having line current and voltage in
phase. The LLC-SRC is designed to operate around resonance frequency to achieve
maximum benefits of LLC converter, having
minimum circulating energy, avoiding hard
commutation of secondary rectifier diodes. Simulation results for the
converter performance are presented which show that the turning off current of
power switches have very low value throughout the charging process and is below
2.4A. Hence, the converter have minimum switching and conduction losses.
REFERENCES:
[1]
H. Wang, S. Dusmez, and A. Khaligh, "A novel approach to design EV battery
chargers using SEPIC PFC stage and optimal operating point tracking technique for
LLC converter," Applied Power Electronics Conference and Exposition (APEC),
2014 Twenty-Ninth Annual IEEE, pp.1683-1689, 16-20 March 2014.
[2]
H. Wang, S. Dusmez, and A. Khaligh, "Design and Analysis of a Full-Bridge
LLCBased PEV Charger Optimized for Wide
Battery Voltage Range," Vehicular Technology, IEEE Transactions on,
Vol. 63, No. 4, pp.1603-1613, May 2014.
[3]
J. Deng, S. Li, S. Hu, C.C. Mi, and R. Ma, "Design Methodology of LLC
Resonant Converters for Electric Vehicle Battery Chargers," Vehicular
Technology, IEEE Transactions on, Vol. 63, No. 4, pp.1581-1592, May 2014.
[4]
Marian K. Kazimierczuk, "Pulse-width Modulated DC-DC Power
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[5]
H. Wang, and A. Khaligh, "Comprehensive Topological Analyses of Isolated Resonant
Converters in PEV Battery Charging Applications," Transportation Electrification
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