Inverter Board, Input Board And Control / Display Board - Lincoln Electric Tomahawk 1500 Service Manual

LINCOLN ELECTRIC Tomahawk® 1500 Service Manual
Figure E.2 – Inverter board, input board and control / display board

Inverter Board, Input Board and Control / Display Board

The 400 VDC created by the buck / boost board is filtered and applied to an IGBT controlled full wave
bridge inverter that is located on the inverter board. The full wave bridge inverter is pulsed width
modulated at 20Khz via control signals sent from the input board. Minimum and maximum output is
achieved and controlled via the PWM signals from the input board. The pulsed DC output of the full wave
bridge inverter is coupled to the primary winding of the main transformer. The transformer primary
current is sensed on the inverter board and this current feedback information is sent to the input board.
There are two normally closed thermostats connected to the inverter board. One thermostat is located
underneath the inverter board and the other thermostat is located in the output choke. If either of these
thermostats opens, due to over temperature, the inverter board will be turned off and the cutting output
will be disabled to allow the unit to cool.
There are several auxiliary supplies created on the input board. These DC supplies are sourced from a wide
range of rectified input voltages (208 VAC to 575 VAC rectified). The input board receives current reference
commands from the control / display board and compares these to the output voltage and current
information received from the output board. The input board then sends the appropriate PWM signals to
the inverter board.
The input board also monitors the torch parts-in-place and trigger circuits and will not send a PWM signal
to the inverter board if the safety circuits are not whole and complete. Thus, no output from the
Tomahawk 1500.
The input board also sends control signals to the buck / boost board and powers the gas solenoid and
cooling fan.
The control / display board functions as the user interface between the operator and the machine. It
receives status and analog signals from the inverter and output boards via the input board and sets the
output current reference command. It also manages the error and alarm signs and the LED functions.
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