Kikusui PLZ-4W Series, User Manual

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A-10 Appendix PLZ-4W
A.2.5 Operation of the CC+CV Mode
The PLZ-4W allows you to add CV mode to CC mode.
■
CC+CV mode operation
When the PLZ-4W is used in CC+CV mode, the PLZ-4W operates as a constant
current load and a constant voltage load (shunt regulator) as shown in Fig. A-12.
When operating as a constant current load, the PLZ-4W sinks the speci
fi ed current
(I) independent of the output voltage of the constant-voltage power supply (V
M
).
When operating as a constant voltage load and V
M
is greater than V, the input volt-
age V is kept constant even when the input current I varies. Current does not fl ow
when V
M
is less than or equal to V.
The switching between the modes is automatic. In the fi g. A-12, R1 is the internal
resistance of the constant-voltage power supply. In constant-voltage (CV) mode, the
PLZ-4W may operate unstably if R1 is low.
Fig. A-12 Equivalent circuit of the CC+CV mode and operation
■
Transition of the operating point: Overpower protection (OPP)
We will consider the case when checking the discharge characteristics of a battery
of Fig. A-12.
Fig. A-13 Transition of the operating point in CC+CV mode (OPP trip
point)
0
CC setting value
CV
setting
value
PLZ-4W Series Electronic Load
Battery
Current I
V
oltage V
I
V
R
1
CV operation
Voltage is constant even
when the current varies
CC operation
Current is constant
even when the
voltage varies
V
M
Input current [A]
Input
voltage [V]
Log scale
V
M
V
Q
Q
S
Constant power line
(OPP setting)
Constant voltage line
(Constant voltage setting)
Operating area
OPP trip point
M
N
I
N
M
1
M
2
P
N
P
N1
Constant current line
(Constant current settings: I
M1
, I
M2
, and I
N
)
I
M1
I
M2