How do I start selecting a Semikron module?

Begin with the DC bus to fix the voltage class, then set the current from the load, choose the topology and housing for the mechanical design, and pick the platform: SEMITRANS for the classic 62 mm, SEMiX for a compact inverter, or SEMITRANS 3+ for the latest chip and the highest current. Those decisions narrow the range quickly.

SEMITRANS, SEMiX or SEMITRANS 3+?

Choose SEMITRANS for the proven 62 mm and 34 mm platform, SEMiX for a low-profile module with the driver on top and a dense layout, and SEMITRANS 3+ for the IGBT 7 chip, higher current and a 175 degree junction in the classic footprint. The mechanical design usually decides the platform.

How do I choose the voltage class?

Start from the DC bus and include the switching overshoot. A 380 to 480 V AC drive rectifies to roughly 560 to 680 V, so a 1200 V module gives the necessary margin, while a 690 V system moves to 1700 V. Never choose the class from the nominal voltage alone. Our FAE team can confirm the class for your bus.

What selection mistakes should I avoid?

The usual mistakes are undersizing the current, ignoring the thermal resistance and choosing a housing that does not fit the heatsink. Each adds cost or risk without benefit, and a module that runs too hot fails early. Validate the choice on the bench before committing the BOM.

How do I choose the gate resistor for a Semikron module?

Start from the datasheet recommendation, then tune on the bench: measure the collector overshoot at turn-off and the EMI spectrum at the switching frequency. Increase the resistance if the overshoot approaches the blocking voltage, and decrease it if switching loss dominates the thermal budget. Separate turn-on and turn-off resistors give the best balance.

Which driver should I pair with the module?

Use a matched Semikron SKYPER or SKHI driver, which provides the isolation, the short-circuit protection and the soft shutdown the module needs. Mount it close to the module to keep the gate loop short, and check that its output current suits the module gate charge. Ask us for a module and driver pairing.

How do I size the heatsink?

Estimate the conduction and switching losses at the actual operating point, then use the module junction-to-case thermal resistance and the interface material to find the required case-to-ambient resistance. Confirm the junction temperature at the worst-case ambient and load. Our FAE team can run the loss estimate for you.

How do I set the dead time?

Set the dead time above the worst-case turn-off time of the switch plus the driver propagation delay, with margin, so both switches in a leg never conduct together. Too little dead time risks shoot-through; too much distorts the output waveform. Verify the dead time on the bench at the operating temperature.

Why use a three-level converter?

A three-level converter halves the voltage step across each device, so the switching loss falls and the output waveform improves, allowing a smaller filter and a higher efficiency. That is why solar, wind and storage converters increasingly use three-level NPC and ANPC topologies at a high DC bus. The trade-off is more devices and a more complex gate drive.

Which module suits a three-level converter?

SEMITRANS 3+ is optimised for modern three-level topologies as well as the classic half-bridge, offering the latest IGBT 7 chip and a 175 degree junction in the proven 62 mm footprint. Choose the voltage class for the full bus with margin. Our FAE team can review your three-level design.

How do I estimate the loss in a three-level stage?

For each of the modules in the topology, estimate the conduction loss from the device current and the saturation voltage, and the switching loss from the switching energy at the operating current and voltage, then sum the two over the fundamental period. An NPC stage shares the loss across more devices, which lowers the junction temperature for the same output. Our FAE team can run the loss estimate.

Does a three-level converter need a special driver?

Yes. A three-level converter has more switches, each with its own isolated supply and gate drive, so the driver design is more involved. Using matched Semikron drivers keeps the isolation, the protection and the timing consistent across the stage. Request a three-level driver review.

My module overheats even at light load. Where do I start?

Measure the gate waveform first. If the device is oscillating or partially turned on by noise, losses rise without load. Then check the turn-off overshoot and verify the thermal interface and mounting torque, because a poor interface masquerades as a device problem. Gate problems often look like thermal problems.

Why is my gate waveform ringing?

Ringing is parasitic oscillation between the gate capacitance and gate-loop inductance. Shorten the gate loop, increase the gate resistance in small steps, or add a ferrite bead close to the package. Keep ringing below about 20 percent of the drive voltage.

How do I stop false turn-on in a half bridge?

Fast dv/dt couples through Miller capacitance and lifts the off-state gate. Use a negative gate rail, a lower-impedance pull-down, or a lower off-transition gate resistance, and measure the off-state gate during a switching event. If the spike crosses threshold, add the negative rail.

Collector overvoltage at turn-off: what next?

Overvoltage comes from stray loop inductance. Tighten the power loop, then increase the turn-off gate resistor slightly or add a clamp, and measure at the module terminals, not the bus. A low-inductance module helps, but the busbar still sets the result. A layout review often removes the overshoot.

Technical Support | Semikron Expertise | BeiLuo

Guides, application notes and troubleshooting from BeiLuo's FAE team covering Semikron SEMITRANS, SEMiX and SEMITRANS 3+ IGBT modules and their gate drivers.

Guides 1 Application Notes 2 Troubleshooting 1 Reviews 0

How to Select a Semikron IGBT Module: A Practical Guide

2026-07-24 - Guides - By Wei Lin

Compare Semikron SEMITRANS, SEMiX and SEMITRANS 3+ IGBT modules by voltage, current, topology and housing to choose the right module for your converter.

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Semikron IGBT Module Application Notes for Drives

2026-07-17 - Application Notes - By Wei Lin

Gate drive, dead time and thermal design guidance for Semikron SEMITRANS and SEMiX IGBT modules in three-phase motor drives, inverters and UPS systems.

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Semikron Three-Level Converter Application Notes

2026-07-10 - Application Notes - By Sun Qiang

Topology, loss estimation and layout guidance for Semikron IGBT modules in three-level NPC and ANPC converters for solar, wind and energy storage systems.

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Semikron Module Troubleshooting and Protection

2026-07-03 - Troubleshooting - By Bai Xue

Diagnosing gate ringing, false turn-on, turn-off overvoltage and overheating in Semikron module designs, with a systematic fault-finding procedure and fixes.

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Meet Our FAE Team

Wei Lin

Senior FAE Engineer, Power Modules

IGBT ModulesGate DriveThermal Design

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Sun Qiang

FAE Engineer, Drives and Topology

Three-LevelMotor DriveLoss Estimation

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Bai Xue

FAE Engineer, Applications

Motor DriveEMCTroubleshooting

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