Introduction to Infineon IGBT Selection

The insulated-gate bipolar transistor, or IGBT, sits at the heart of nearly every modern power conversion system. Motor drives, solar inverters, EV traction systems, uninterruptible power supplies, and induction-heating appliances all rely on IGBTs to switch voltages ranging from a few hundred volts to well over a kilovolt at currents measured in tens or hundreds of amperes. Infineon is one of the world's leading IGBT manufacturers, and their product portfolio spans discrete devices, modules, and intelligent power modules (IPMs) covering virtually every power class. Choosing the correct Infineon IGBT for your design, however, requires more than picking the first device that exceeds your voltage and current requirements. This guide explains the parameters that matter most and shows you how BeiLuo FAEs approach IGBT selection for customers across industrial, automotive, and renewable-energy applications.

Understanding IGBT Voltage Classes

Infineon divides its discrete IGBT portfolio into several collector-emitter breakdown voltage classes: 600 V, 650 V, 1200 V, and 1700 V are the most common. The 600 V and 650 V classes target single-phase power-factor-correction stages, low-voltage motor drives operating from a 400 V AC bus, and consumer appliance inverters. The 1200 V class is the workhorse of three-phase industrial drives and grid-tied solar inverters running from 480 V or 690 V AC mains. The 1700 V class addresses high-power traction converters, large UPS systems, and medium-voltage drives.

A common rule of thumb is to derate the IGBT blocking voltage to approximately 50 to 60 percent of its rated BVCES to account for transient overvoltages caused by parasitic inductance in the DC bus. So for a 600 V DC bus you should select a 1200 V rated device, and for a 400 V DC bus a 650 V device is generally appropriate. BeiLuo consistently stocks the 1200 V class because it covers the widest range of industrial motor-drive applications.

Current Rating and Safe Operating Area

The IGBT continuous collector current rating (IC at a specified case temperature) tells you the steady-state thermal limit, but it is the peak current and the safe operating area (SOA) curve that determine whether the device will survive fault conditions. For motor-drive applications, the short-circuit withstand time (tsc) is critical: Infineon Trenchstop and IGBT4 devices typically specify a short-circuit withstand time of 10 microseconds at rated voltage, which gives the system controller time to detect the overcurrent and turn off the gate signal safely.

To size the current rating, start with the RMS output current required by your load, then apply a derating factor of 0.7 to 0.8 for the package thermal resistance and expected ambient temperature. For example, if your motor drive needs 30 A RMS output, you should select an IGBT rated for at least 40 A. The Infineon IKW40N120H3 is a 40 A, 1200 V Trenchstop IGBT in a TO-247 package that BeiLuo stocks in volume and recommends for industrial drives in this current range. Its low VCE(sat) of 1.95 V at 25 degrees C reduces conduction losses, and its relatively soft turn-off characteristic limits EMI generation at switching frequencies below 20 kHz.

Switching Frequency and Switching Losses

Every time an IGBT switches, it dissipates energy as turn-on loss (Eon) and turn-off loss (Eoff). At low switching frequencies (2 to 4 kHz) these losses are manageable, and the device spends most of its time either fully on or fully off with small conduction losses. As switching frequency rises toward 16 kHz or higher (common in servo drives demanding low acoustic noise), switching losses dominate the power budget and require careful thermal management or a move to a faster switching technology such as silicon carbide (SiC) MOSFET.

Infineon characterizes Eon and Eoff in the datasheet at standard test conditions. When comparing devices, check that the test inductance (LS) and gate resistance (Rg) match your application. Lower gate resistance speeds switching, cutting Eoff, but increases the current spike at turn-on and the dv/dt stress on the freewheeling diode. BeiLuo FAEs routinely help customers balance gate resistance between 5 ohm and 22 ohm to optimize the trade-off between switching loss and EMI signature.

Thermal Package and Heatsink Design

The thermal resistance from junction to case (Rth(j-c)) determines how much power the IGBT can dissipate for a given junction temperature rise above the heatsink temperature. TO-247 packages typically offer Rth(j-c) values between 0.3 K/W and 0.7 K/W for discrete IGBTs, while power modules can achieve 0.1 K/W or lower by bonding multiple chips directly to a copper substrate.

Calculate total power loss as the sum of conduction loss (VCE(sat) times average current) and switching loss (Eon plus Eoff times switching frequency). Then solve the thermal equation: Tjunction = Tambient plus (Ploss times (Rth(j-c) plus Rth(c-s) plus Rth(s-a))), where Rth(c-s) is the contact resistance of the thermal interface material and Rth(s-a) is the heatsink-to-ambient resistance. Infineon publishes thermal impedance curves (Zth) that allow you to account for the transient thermal mass of the chip and package, which is essential for pulsed-load applications like elevators and cranes.

Gate-Drive Requirements

Infineon IGBTs require a gate-emitter voltage (VGE) of typically plus 15 V for full saturation and minus 7 V to minus 15 V for fast, reliable turn-off with adequate noise immunity. The gate charge (Qg) listed in the datasheet determines the peak current your gate-drive IC must supply to achieve the desired switching speed. A rough estimate for gate-drive supply current is Qg times switching frequency.

Isolation is mandatory in most bridge topologies because the high-side emitter floats at a switching node voltage. Infineon offers dedicated gate-drive ICs such as the 1ED020I12-F2 that integrate isolated power supply and signal path in a compact package, simplifying PCB layout and reducing bootstrap component count. BeiLuo stocks these gate-drive ICs alongside the IGBT devices so customers can prototype complete half-bridge circuits from a single supplier.

BeiLuo Stock and Procurement Tips

BeiLuo maintains authorized inventory of Infineon discrete IGBTs with full lot traceability and Certificate of Conformance documentation. Our most popular discrete devices in the 1200 V class ship within three business days for standard orders. For volume orders above 500 pieces, we can provide lead-time commitments aligned with Infineon factory scheduling.

When evaluating new IGBT designs, we recommend requesting a small evaluation lot of 10 to 20 pieces for board-level validation before committing to a full production purchase order. BeiLuo FAEs can assist with application review, suggesting alternative part numbers from the BeiLuo selection guide portfolio if your primary candidate becomes constrained. Contact our technical sales team for consolidated quotes that include matched gate-drive ICs and current-sense resistors.

Summary: Key IGBT Selection Checklist

To select the right Infineon IGBT, work through this checklist: (1) Determine your DC bus voltage and apply a 50 percent derating to choose the blocking voltage class. (2) Calculate RMS output current, apply a 0.75 derating factor, and size the collector current rating accordingly. (3) Estimate total power loss at your target switching frequency and verify it stays within the thermal budget. (4) Check the short-circuit withstand time against your overcurrent protection response time. (5) Confirm that your gate-drive design supplies adequate peak current for the IGBT's gate charge. (6) Verify that BeiLuo has stock on hand or a confirmed lead time that fits your production schedule. Following these steps will help you arrive at a reliable, cost-effective IGBT selection on the first spin.