CHAPTER 3: USING PROGRAMMING FUNCTIONS
IS-300CA INVERTER POWER SUPPLY
990-418 3-9
(Note) Control method of the inverter-type welding power supply
CONTROL METHOD FEATURE APPLICATION CONTROL MECHANISM
Primary constant-current
control
(PWM effective value control)
Requires no connection of
toroidal coil on the secondary
side of the transformer.
Requires turn ratio setting of
the inverter-type transformer.
The loss inside the
transformer is not considered.
Used for welding in
a robot or an
environment where
the weld head
moves and that
causes
disconnection of
toroidal coil and
cable.
Detects the primary current by the current
sensor mounted into the power supply to
compare the measured current obtained by
calculating with each control frequency to
the primary current obtained by “set current
÷ turn ratio”, and controls pulse width so
that there is no difference in these values.
Secondary constant-current
control
(PWM effective value control)
Compared to the primary
constant-current control, the
current accuracy is high since
the welding is directly
controlled, being detecting the
welding current.
Commonly used for
general welding.
Detects the welding current with toroidal
coil to compare the measured current
obtained by calculating with each control
frequency to the set current, and controls
pulse width so that there is no difference in
these values.
Secondary constant-power
control
(PWM effective value control)
Controls so that the power
between electrodes becomes
constant.
Responds to change in work
piece state during welding to
make heat input constant.
Used when you
want to reduce
expulsion in early
welding, shunt
current is occurred
at welding, or make
heat generation
constant.
Detects the welding current with toroidal
coil and the voltage between electrodes with
the voltage detecting cable to compare the
power calculated by the measured current
obtained by calculating with each control
frequency and voltage to the set current, and
controls pulse width so that there is no
difference in these values.
Primary constant-current peak
value control
(PWM peak value control)
Requires no connection of
toroidal coil on the secondary
side of the transformer.
Requires turn ratio setting of
the inverter-type transformer.
The loss inside the
transformer is not considered.
Compared to the effective
value control, the rise of the
current is fast, but the
effective current changes
depending on how large the
current ripple is.
Used for welding of
coated metal or
dissimilar metal.
Sets the primary current obtained by the set
current and the transformer turn ratio as
current limiter, and controls pulse width so
that the switching is turned off when the
primary current detected by the current
sensor mounted into the power supply has
reached to the current limiter.
Secondary constant-voltage
control
(PWM effective value control)
Controls with the voltage
between electrodes.
Provides welding without
expulsion by making voltage
from the rise constant and
reducing the current.
Used for welding of
high specific
resistance material,
welding of high
contact resistance
work piece such as
cross wire, and
projection welding,
which has resistance
change in early
welding to reduce
expulsion.
Detects the voltage between electrodes with
the voltage detecting cable to compare the
measured current obtained by calculating
with each control frequency to the set
voltage, and controls pulse width so that
there is no difference in these values.
Constant-phase control
(Non-constant current)
Welding with the fixed pulse
width. No feedback control.
Used for special
cases such as the
test of welder, and
not used for normal
welding.
Controls switching with the set pulse width.
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