Advanced Welding Processes: Technologies and Process Control

Off line
storage
Operator
interface
Welding power source technology 41
Program
EPROM
Input – Output
interface
3.15 Microprocessor control system.
Parameter
EPROM
It is common now to use a particular form of microprocessor which is
known as a digital signal processor (DSP). The specifications of these devices
vary, but often include all the peripherals required for monitoring and control
as well as communication facilities for external interrogation of the system
as discussed in Chapter 2. They provide a reliable and cost effective means
of achieving sophisticated control and facilitate the synergic control systems
mentioned later in Chapter 7.
Although the dedicated microprocessor control approach does not allow
complete design flexibility (the software will often represent a significant
investment and revisions may be costly), the designer can build in the ability
to change certain parameters based on a knowledge of the welding process
requirements. This may be used to simplify the operation of the equipment
or to provide the user with the ability to reprogramme key process variables.
3.5.3 Programming and one-knob control
User RAM
System communication bus
Power source and wire
feed unit electronic
control system
The concept of a single adjustment knob for ‘complex’ parameter setting, for
example in the GMAW process, is not new and power sources using preset
wire feed and voltage controls and a single condition selector switch were
available in the mid 1970s. However, without electronic feedback control,
novel, but unreliable, methods of mains voltage stabilization had to be
employed. With electronic power regulation and feedback control power
sources may be programmed by the supplier or the user with reliable ‘optimum’