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E-12

E-12

THEORY OF OPERATION

FIGURE E.10 – TYPICAL IGBT OUTPUTS

25sec sec

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sec

50 sec

MINIMUM OUTPUT

24 sec

1sec 24sec 50sec

MAXIMUM OUTPUT

sec

1 sec

PULSE WIDTH MODULATION

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The term PULSE WIDTH MODULATION (PWM) is used to describe how much time is devoted to conduc- tion in the positive and negative portions of the cycle. Changing the pulse width is known as MODULATION. Pulse Width Modulation is the varying of the pulse width over the allowed range of a cycle to affect the output of the machine.

MINIMUM OUTPUT

By controlling the duration of the gate signal, the IGBT is turned on and off for different durations during a cycle. The top drawing below shows the minimum out- put signal possible over a 50-microsecond time period.

The shaded portion of the signal represents one IGBT group1, conducting for 1 microsecond. The negative por- tion is the other IGBT group. The dwell time (off time) is 48 microseconds (both IGBT groups off). Since only 2 microseconds of the 50-microsecond time period are devoted to conducting, the output power is minimized.

MAXIMUM OUTPUT

By holding the gate signals on for 24 microseconds each and allowing only 2 microseconds of dwell or off time (one microsecond during each half cycle) during the 50 microsecond cycle, the output is maximized. The dark- ened area under the minimum output curve can be com- pared to the area under the maximum output curve. The more darkened area, the more power is present.

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1An IGBT group consists of the sets of IGBT modules grouped onto one switch board.

POWER WAVE 455M/MSTT

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Lincoln Electric SVM173-A service manual Pulse Width Modulation, Minimum Output, Maximum Output
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SVM173-A specifications

The Lincoln Electric SVM173-A is a highly regarded welding power supply that stands out for its advanced features, robust performance, and innovative technologies. This machine is specifically designed to meet the demands of both industrial and commercial welding applications, making it a versatile choice for professionals.

One of the main features of the SVM173-A is its high efficiency, which contributes to reduced energy costs and enhanced productivity. The device operates on a powerful DC output, ensuring stable and reliable arc performance. This is particularly beneficial when working with various materials, allowing for smooth and consistent welds.

The SVM173-A leverages Lincoln Electric's proprietary inverter technology. This innovation allows for a lighter weight and more compact design without compromising on power. The inverter technology also enables precise control of the welding parameters, which is critical for maintaining quality across different welding tasks. Additionally, the machine features a wide input voltage range, accommodating various power sources and enhancing its adaptability on job sites.

Another key characteristic of the SVM173-A is its user-friendly interface. The machine is equipped with an intuitive control panel that allows users to easily adjust settings, making it accessible for both novice and experienced welders. The digital display provides clear readouts of output parameters and error notifications, facilitating quick troubleshooting in the field.

Safety is paramount in welding operations, and the SVM173-A incorporates several protection features. These include overcurrent protection, overheating protection, and circuit protection, ensuring that the machine operates safely and efficiently under various conditions.

The SVM173-A also supports a wide range of welding processes, including MIG, TIG, and stick welding. This flexibility makes it an ideal choice for workshops that require a multi-process machine capable of handling diverse applications. Furthermore, the SVM173-A supports spool gun operation, which is particularly useful for aluminum welding, enhancing its versatility even further.

In summary, the Lincoln Electric SVM173-A is a powerful and adaptable welding machine that combines innovative technologies, user-friendly features, and robust safety mechanisms. Its high efficiency, precision control, and multi-process capabilities make it an excellent investment for professionals seeking reliable performance in demanding environments. Whether for heavy-duty industrial use or more specialized applications, the SVM173-A stands as a testament to Lincoln Electric's commitment to quality and innovation in welding solutions.
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