Bi-directional DC-DC converter with Soft Switching Cell Student: Marek Ryłko Co-ordinators: Dr....
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Transcript of Bi-directional DC-DC converter with Soft Switching Cell Student: Marek Ryłko Co-ordinators: Dr....
Bi-directional DC-DC converter Bi-directional DC-DC converter with Soft Switching Cellwith Soft Switching Cell
Student: Marek Ryłko
Co-ordinators: Dr. Michael G. Egan
Dr. John G. Hayes
EPE-PEMC 2006, Portoroz 31th Aug 2006
Topology basics
• Introduce Soft Switching Cell
• 5 extra elements
– 2 aux. Switches
– 2 aux. Diodes
– Autotransformer
Hard Switching
Soft Switching
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Fundamentals of operation
Continous conduction mode• Fixed bus-voltages• Operating frequency – above audible noise
Maximum frequency limited by system topology and devices properties
• Efficiency 92-98%• Hardware overcurrent protection• Main switches operates as thyristor-dual• Fully ZVCS switch-on main switches and snubber assisted
switch-off• ZCS switch-on and ZVCS turn-off of auxiliaries• Main diodes reverse recovery limited by soft-switching cell
inductance
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Main inductor current
Resonant ind. current
Main switch current
Flywheeling diode current
Pole voltage
Low voltage bus current
Main inductor voltage
Basic waveforms - BOOST
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Main inductor current
Resonant ind. current
Main switch current
Flywheeling diode current
Pole voltage
Low voltage bus current
Zero Current Crossing Mode
Basic waveforms - ZCCM
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Main inductor current
Resonant ind. current
Main switch current
Flywheeling diode current
Pole voltage
Low voltage bus current
Main inductor voltage
Basic waveforms - BUCK
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Soft Switching boundary
22 cos1 Vtaavp
1cosmin t
0)1(0min
2 aatvt
p
2
1a
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Pole voltage swing (boost):
Minimum value is achieved for:
Pole voltage must reach zero:
Soft Switching boundary is:
Transformer turn ratio
• Presented boundary for soft switching refer to auxiliary voltage VS
• Damp resistance is present Rd and take part as voltage drop
• Initial conditions are significant factor when main current is large
• Diodes voltage drop affect soft switching
• Voltage swing must be overestimated to take into account main-switch turn-
on time 22
22
542
42max
2
11
1
12
Di
Di
DD
DVL
dV t
t
VVV
VVaI
V
R
e
an
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Duty factor
• Hard switching (square pole voltage)
• Soft switching rr = 0 (deformation of rising and falling edge)
2
1
V
rIVD rLeffective
Because bus voltages are fixed, the duty factor depends on main inductor current as derivative of average value of pole voltage
20
222
2
20
2220
22
2
1
2 1
211arccos
1arccos
2
1
1 ZIVa
ZIaVZIaaV
a
a
TV
rIV
TVa
LID
L
LLLrLapp
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
0 100 200 300 400
I
0.2
0.4
0.6
0.8
1
D
DvsIL, Blue:Pspice, Green&Red:Ideal rr0, 150kHz
System characteristic DvsI
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Damped Cell – non ideal case rr ≠ 0
• Damped cell Duty factor
20
222
2
20
2220
22
22
22
22
22
2
22
2
2
2
1
1
211arccos
1arccos
2
1
21arccos
arccos2
11
1
1ln
ZIVa
ZIaVZIaaV
a
a
VrIa
rIaVVr
V
Ia
VrIa
rIa
Va
a
Va
aVVa
TrIVa
Va
Tr
L
V
rIVD
L
LL
rL
rLr
L
rL
rL
rLr
rLapp
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
0 100 200 300 400I
0.2
0.4
0.6
0.8
1
D
DvsIL, Red:Pspice, Purple&DarkGreen:Damped rr0.3, 150kHz
System characteristic DvsI
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
100 200 300 400IL
0.2
0.4
0.6
0.8
1
D
DvsIL, Blue&Black:HS, Red&LightGreen :Ideal, Purple&DarkGreen:Damped, 150kHz
Difference between ideal and damped system
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Summary of soft switching system
• EMI improvement
• Good efficiency
• Decreased switching losses
• Distributed heat radiation
• Silent operation (over audible frequencies)
• No significant volume improvement
• More complex system
• Gain affected due to cell operation
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
Further research plan
• Development of systems above 10kW• Compare with other bi-directional topologies
– Interleaved, multiphase converters – Comparison of high ripple current and low ripple
current cases– Investigation of IGBT operation in soft-switched
regimes– MOSFETs in interleaved systems for high power– Inductor design– Coupled inductor approaches– Fully resonant approach– Hardware, FPGA’s for control– Conference papers
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END
THE END
Thank you for your attention!
Topology
Fundamentals
BOOST
ZCCM
BUCK
SS Boundary
Turn ratio
Duty – ideal
Duty – damped
Summary
Further plans
END