ST covers a consistent part of the rapidly growing welding market in Europe and Asia, while it is the largest supplier in the USA.
MOSFETs and IGBTs are present in both the power factor corrector and inverter stages of welding equipment. A wide range of devices have already been developed for PFCs and a power range will soon become complete for the inverter stage. Focus will be put on devices with fast-recovery body-drain diodes in the 800V and 900V range.
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The devices already in production are realized with the standard PowerMESH and the first generation MDmesh technology. For products under development, however we are using the latest SuperMESH generation of our standard technology and for advanced devices the improved version of MDmesh. Many of these devices are housed in the ISOTOP package as it is well suited to most welding applications. Its high current and insulation capabilities improve thermal performance and allow safety operations. |
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Welding applications can basically be split into low and high frequencies.
The first employs a low frequency transformer (50 to 60Hz) as highlighted in the following block diagrams.
Different topologies for low frequency welding
High frequency applications are becoming the most popular, used especially in new designs and based on the configuration shown below.
Typical full bridge topology for industrial and commercial high frequency welding
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Conventional power sources use transformers with the view “the bigger, the better”.
Now, instead, this approach is moving towards the concept of “the smaller, the better”. In fact for a given power, the volume of a transformer is related to the frequency, i.e. increase the frequency and the volume of the transformer will be reduced.
The higher the switching frequency the lower the size and weight of the welding machine
The result of such an approach is that size and weight are reduced to a minimum i.e. moving from 50Hz to 100kHz the weight is reduced from 70kg to only 3kg. Most welder producers are moving towards this high frequency topology for new designs.
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High Frequency Welding Machines |
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