IEEE Power Electronics Magazine - December 2015 - 42

Q19 0 !0 3

50
25,0 !1,0

Maximum
Max
ximu
i m08
0, 26 !1 0

Q 0 15

Release Tape

Detail A

Release Tape

0 !0
03
50
!10
170 !10
FIG 2 A rounded coil like the WE-WPCC 760308101214 offers a thickness of 0.8 mm.

WPC is 110-205 kHz, whereas it is
key specifications of one of the WE
between 232 and 278 kHz for PMA; the
products, WE-WPCC 760308103202,
inductance requirement to work on
with coils from other wireless coil
The key element
these ranges of frequency is different.
manufacturers. The specifications
in the wireless power
WE has moved forward in creating
of each parameter listed in Table 1
coils to help the end-product designer
for the WPCC product are exceptioncharging system is the
choose a coil that complies with both
ally good when compared with simiwireless power coil.
the WPC and PMA standards; such
lar products from competitors. The
coils are called dual-standard coils.
ferrite shield used in the coil has a
Some of the WE dual-standard coils
very important role in determining
are WE-WPCC 760308102210, WEthe number of turns to be placed and
WPCC 760308102213, WE-WPCC 760308103211, and WEthe thickness of the overall coil. A WPCC's carefully enWPCC 760308103206.
gineered ferrite shield helps to achieve the performance
presented in Table 1 while acheiving the smallest thickness. The ferrite shield used in the coil is prefractured
Maximum Power Transfer Coils
ferrite material.
One of the significant concerns in wireless power transfer technology is the efficiency of the power transfer
from the transmitter to the receiver coil. The amount of
Dual-Standard Coils
power transfer is directly proportional to the coupling
Today, there are two inductive wireless charging standards,
factor; the better the coupling, the higher the power
Qi from the Wireless Power Consortium (WPC) and PMA
transfer. Factors such as the size and ratio of the transfrom the Power Matters Alliance. The frequency band for
mitter and receiver coils, the distance
between the coils, and the coil position are
Table
1.
A
comparison
of
key
specifications
of
WE-WPCC
the major factors that affect coupling
-
760308103202 with similar coils from other manufacturers.
between coils. With its extensive experience in the field of engineering and manuParameter
wE
competitor a competitor B competitor c
facturing WPCCs, WE has created coils
12.0
9.7
11.3
10.5
Inductance (nH)
that maximize the power transfer to the
Quality factor
33 at125 kHz 30 at 200 kHz
18 at 100 kHz
N/A
receiver (Figure 3).
160
200
225
200
dc resistance
The unique design features of the ferrite
^mX h
shield
used in the coil are the elevated rim on
Thickness (mm)
0.958
1.05
1.10
1
the
edge
of the ferrite and the elevated ferOperating
105
N/A
N/A
70
temperature (°C)
rite plateau at the center of the coil, which
help to direct the magnetic flux and increase

IEEE PowEr ElEctronIcs MagazInE

z December 2015

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - December 2015