Transcript スライド 1 - Indico

Considerations on Step-Down
Piezoelectric Transformers
Masatosi Imori, Yoshinobu Unno1, and Yasumasa Kanada2
ICEPP, University of Tokyo
7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan
1KEK
1-1 Oho, Tsukuba, Ibaraki 305-0801 Japan
2Information Technology Center, University of Tokyo
2-11-16 Yayoi, Bunkyo-ku Tokyo 113-8658, Japan
Equivalence Circuit of Step-Down PT
PT Newly Provided by Tokin
R concerns input voltage
• Let input voltage be 120 V and the current
through R be 100 mA,
• Then power to the transformer is 12 W and the
power dissipated by R is less than 100 mW .
• Power loss at R is less than 1 %.
• R becomes smaller for the lower input voltage.
Dependence of Impedance on Frequency
Resistance of Electrode is Rd
• Impedance becomes minimum around a serial resonance
• Impedance becomes maximum around a parallel resonance
• Influence of Rd on resonance is different between the serial
and the parallel resonances
• The resistance of the electrode is identified with Rd by the
experiment where the influence is measured by changing
number of the layers
Optimal Resistance
• Cd2 is the capacitance in the equivalence circuit.
Let f be the carrier frequency, then optimal
resistance Rop is defined by
R op
1

 Cd 2
where   2  f
• The load equal to the optimal resistance attains
the maximum efficiency
Capacitance Cd2 to match load
R EQ
8
 2 RL

Let output capacity be 2 V 4A, then RL= 0.5Ω, and REQ= 0.4Ω.
Let f be 100 kHz then Capacitance Cd2 to match load is about 4 μF
Stacked Ceramic
Capacitor
Recently
Number of Layers
1000
Thickness of Layer
~ 1μ
Capacitance
up to 100 μF
Stacked Piezoelectric Actuator
Sheet of Electrode
Polarization
Layer Made of Piezoelectric Material
Step-Down Piezoelectric Transformer
PT of Large Output Current
• Tokin Corporation is a branch of NEC
Corporation. Tokin people talked to NEC
people about the development of such the low
voltage step-down PT.
• The decision about the development will be
based on prospects of such the transformers,
where the demand for the transformers in a
high energy physics is not considered so much
as we expect.
Dedicated Power Supply
• Low voltage step-down PT’s, which can be
manufactured without further development or
studies, are characterized by the optimal
resistance around or larger than 10 Ω.
• An efficient power supply using the PT can be
implemented for the load larger than 10 Ω.
• It is better to prepare a dedicated power
supply to each channel.
Ground Isolation at Individual Channels
Due to the ground isolation at the
individual channels, the dedicated
power supplies will contribute to
reducing the noises caused by
ground loops.
Isolation Coupler Using PT
The PT with a simple driver and a receiver
could work as an isolation coupler
Example of Ceramic Gyro to See Possible Size of
Isolation Coupler
Acknowledgement
We would like to thank Tokin Corporation