switched capacitor converter with continuous conversion ratio · resonant switched capacitor...
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Switched Capacitor Converter with
continuous conversion ratio
Mert Turhan
20.06.2017
DC/DC converter topologies 1
► Capacitive Converter ► Inductive Converter ► Linear Regulator
Advantages of Switched Capacitor Converter (SCC)
• No magnetic elements − No inductive switching losses − Can be fabricated as IC
• High power density
2
0
20
40
60
80
100
120
140
160
Energy Density (µJ/mm2)
Energy density of an inductor and a capacitor
Inductor (10µH Coilcraft SMT)
Capacitor (1µF T-Y Ceramic)
149
~1
Integration 3
► Inductive ► Capacitive
Source: V. Wai Shan Ng ,'Switched Capacitor DC-DC Converter: Superior where the Buck Converter has Dominated', PhD Berkely
DC-DC step-down inductor based with the inductor marked. Vin=5V-23V, Vout=1V-17V and Iout=3A
DC-DC step-down switched-capacitor converter (SCC) Vin=7.5V-13V, Vout=1V and Iout=1A
Why not SCC?
• Output voltage regulation is tied to efficiency
• Not suited for high current/power
• Lots of switches and gate driver
• Voltage balancing for many caps
• Current stress
4
Voltage Conversion for Dickson Converter 5
3:1 Dickson Converter First phase, odd switches are open
Second phase, even switches are open
Step-up Switched Capacitor Converter 6
Resonant Switched Capacitor Converter
• Even the efficiency increases, the output voltage is discrete and is tied to the load
7
60
65
70
75
80
85
90
95
100
0,3 0,8 1,3 1,8
Effi
cien
cy (
%)
Output Current (A)
Conventional SCC without Lr
r=20mΩ r=50mΩ
Resonant SCC with Lr
r=20mΩ
r=50mΩ
1,5
1,7
1,9
2,1
2,3
2,5
0,3 0,8 1,3 1,8 O
utp
ut
Vo
ltag
e (V
) Output Current (A)
Conventional SCC without Lr
r=20mΩ r=50mΩ
Resonant SCC with Lr
r=20mΩ
r=50mΩ
SCC with Continuous Conversion Ratio
8
Derivation of SCC with Continuous Conversion Ratio 9
The step-up SCC 10
• To connect the capacitor cells in order to increase the conversion ratio
Step-up SCC with 2 SCs 11
Conversion Ratio versus duty cycle (δ)
Operation of the step-up SCC
12
Efficiency
Parameters
C1, C3 0.1µF
C2, C4 10µF
L 2.2µH
fsw 215kHz
Vin 20-40V
Pout 100W
13
Loss distribution of the converter
14
Size comparision
• Four Level Boost Converter (FLBC) Balancing circuit was not taken into account
15
• SCQRC
%12 less
Conclusions
• Capacitors may be used in order to minimize the size of the inductor
• There is no unbalancing problem at charge pump topoplogy
• Capacitor cells may be used to increase conversion ratio without extra loss
16
Switched Capacitor Converter with
continuous conversion ratio
Mert Turhan [email protected]
20.06.2017
18
Source: Asmarashid Bin Ponniran, Koji Orikawa, and Junichi Itoh,
Minimum Flying Capacitor for N-Level Capacitor
DC/DC Boost Converter