The 3-level approach is ideal in applications where undistorted output voltage and current waveforms are needed such as uninterruptible power supply (UPS) systems and solar inverters. MiniSKiiP, SEMITOP and SKiM 4 IGBT modules will now include variants with 3-level topologies.     

The baseplate-free SKiM4 module is the most powerful IGBT module in the range, with rated currents of between 200 A and 600 A. Power levels as high as 250 kVA can be achieved without needing to connect several modules in parallel. SKiM4 modules will be available in TNPC (T-Type Neutral Point Clamped) topology for 650 V and 1200 V and NPC (Neutral Point Clamped) topology for 1200 V. The TNPC modules can deliver up to 900 VDC and 480 VAC, while the NPC variants can push the EU Low Voltage Directive to its limits of 1500 VDC and 1000 VAC.     

For smaller currents, baseplate-free, spring-contact IGBT MiniSKiiP modules are available. These offer solder-free mounting and are intended for rated currents of between 75 A and 200 A and reverse voltages of 650 V, offering powers of up to 85 kVA. At 4.9 A/cm², the power density is high compared with competitor products, making this module ideal for use in compact systems. A further advantage of these modules is the easy single-screw connection between module, heat sink and controller board.     

The counterpart to the solder-free MiniSKiiP modules is the SEMITOP, an IGBT module that is 12 mm high and soldered on to power circuit boards for use in applications with current ratings of 20 –150 A. These baseplate-free solder-connection modules will be available in NPC topology and can deliver up to 65 kVA. The voltage rating is 600 V.     

SEMITOP and MiniSKiiP modules are compact because they do not need solid busbars.     

3-level technology was originally intended to be used to control voltages that were greater than the reverse voltage of the semiconductor device. Now the main advantages of this technology relate to the output voltage waveform: instead of the full positive or negative DC link voltage, now half the DC link voltage is available for each side.     

With 3-level technology, the output waveform is closer to an ideal sine wave than is the case for conventional 2-level topologies. The biggest advantage of 3-level technology is the lower distortion factor and consequently reduced filtering requirements. This is particularly important in applications where undistorted output voltage and current waveforms are needed, e.g. uninterruptible power supply systems or solar inverter applications.     

Semikron manufactures power modules in two different 3-level topologies: NPC (Neutral Point Clamped) and TNPC (T-Type Neutral Point Clamped), both of which have their advantages.     

The advantage of NPC technology is that it allows for a higher overall DC link voltage than each individual semiconductor die would be able to block. This enables manufacturers of solar inverters to apply a DC link voltage of up to 1500 VDC to the power modules as opposed to the maximum DC link of around 1100 VDC in 2-level modules.      

In terms of error management, NPC topology is less complex than TNPC, although the same high-quality output voltage waveform is achievable with both topologies. On the other hand, TNPC modules are slightly more powerful than NPC modules, since they use eight rather than ten different semiconductor dice.

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