Learn About Digital Control Arc Welding Machine

A digital control arc welding machine comprises auxiliary circuits connected to a digital signal controller. These auxiliary circuits can be manipulated remotely, or monitored in real time. This allows the user to perform remote diagnosis and upgrade, as well as implantation of welding data.

The auxiliary circuits may be configured to provide a high degree of safety and reliability. In some instances, the interface may be integrated with an external computer 801. Depending on the nature of the digital controller, the auxiliary circuits can be used for a variety of functions. For example, the auxiliary circuits may be able to detect malfunctions and update the controller accordingly. Moreover, the auxiliary circuits may be accessed for program downloads.

In addition to the current waveforms, the controller may also be able to control various parameters of the current, such as the shape and size of the waveform. Additionally, the controller may be able to control the arc voltage and the arc impedance. As an example, the arc impedance may be low or zero during arc initiation, and be large or zero during arc completion. However, the arc impedance can change rapidly during welding operation. To avoid a sudden change in the arc impedance, the controller may be able to control other factors, such as the rate at which the current levels change between short-circuit and open-circuit.

One of the primary functions of the digital controller is to calculate the duty cycle term, or PWM signal. This duty cycle term is computed by combining various terms. Some of these terms include the droop term, which accounts for a non-ideal transfer function of the welding power supply. Other terms include the input rectification circuit, which is responsible for controlling the amount of voltage dropped across the equivalent inductance and resistance of the weld cable.

Another function of the digital controller is to receive and process the feedback signal from the output terminals. The resulting filtered voltage feedback signal can be clamped to a preset value to reduce the effect of induced voltage in the feedback signal due to the weld cable inductance. This enables the welding power supply to be operated as a controlled current source.

An exemplary clamped current plot illustrates the effect of digital controller clamping. Also, exemplary clamped voltage plots indicate the effects of induced voltage in the feedback signal due, in part, to the weld cable inductance. If the induced voltage is too high, the feedback voltage can be lowered to a preset value, which can dampen the ringing of the feedback voltage.

In addition, the digital controller may perform additional functions, including controlling status indicators and relays. Further, it may use bus voltage feedback to calculate the duty cycle, as well as using additional signals in combination with the feedback signal to calculate the duty cycle. Depending on the embodiment, the digital controller may be able to improve the induced voltage in the voltage feedback signal.

Embodiments of the presently disclosed digital controller are designed to allow for improved digital PWM control, as well as limiting the effect of induced voltage in the feedback voltage. Digital controllers are also able to provide feedback values, which may represent the state of the welding power supply. Using feedback values, the digital controller may calculate the next duty cycle term, and control the welding power supply accordingly.