Why Module Selection Deserves Care

The power module is the most consequential component in an inverter. It sets the voltage class, the losses, the heatsink size and, in many cases, the reliability of the whole product. Choosing the wrong module late in a project costs time and money, which is why a structured selection process pays for itself. This guide walks through a repeatable method for selecting a Mitsubishi Electric IGBT module or IPM, using the T-series modules and the G1 and V1 series IPM as the candidate set.

Step 1: Fix the Voltage Class

Start with the DC bus. A 380 to 480 V AC drive rectifies to roughly 560 to 680 V, and switching overshoot adds more, so a 1200 V device provides the necessary margin. Lower-voltage systems may use a 650 V class, while 690 V systems move to 1700 V. Never choose the voltage class from the nominal bus alone; include the switching overshoot you expect, because the device must survive the peak, not the average.

Overshoot and Margin

The commutation loop inductance and the switching speed set the overshoot. A module shrinks the loop compared with discretes, which reduces overshoot, but the DC-link layout and capacitor placement still matter. Leave at least fifteen percent margin between the worst-case peak and the module's blocking voltage, and measure overshoot at the module terminals during validation.

Step 2: Set the Current

Continuous current plus overload current sets the current rating. A motor drive may draw 150 percent of rated current for several seconds during acceleration, and compressor loads draw high current at start-up. Choose a module whose rated current covers the worst case at the expected case temperature, then verify junction temperature with the thermal path. Current ratings are specified at a case temperature, so a hot environment requires derating.

Switching Frequency

Switching frequency is the next filter. Below about 15 kHz, conduction loss dominates, so a low saturation voltage device is efficient. Above 15 kHz, switching loss grows quickly, so the gate drive and the commutation loop become critical. Mitsubishi Electric's CSTBT chip keeps loss low enough to run at practical frequencies within a modest heatsink.

Step 3: Choose the Integration Level

Mitsubishi Electric offers two levels of integration that matter here. A T-series IGBT module gives the most circuit flexibility, with 2in1 dual and other configurations and a flat, isolated base. A G1 or V1 series IPM goes further and adds the drive circuit, the protection and the inverter bridge, so a microcontroller drives it directly. The right choice depends on current level, board space, production volume and how much gate-drive work you want to own.

Module or IPM

Use IGBT modules when you need the highest current or a custom gate drive, and IPM when you want the simplest, most compact power stage. Many designs combine a module bridge with an IPM for an auxiliary axis.

Step 4: Confirm the Thermal Design

Thermal design decides reliability. Begin from the datasheet junction-to-case thermal resistance, add the interface and heatsink resistance, and verify junction temperature at worst-case current and ambient. The 4000 Vrms isolation of the T-series modules and the flat base make mounting straightforward. Use a thin, uniform thermal interface material and the specified mounting torque.

Step 5: Validate on the Bench

Before committing to volume, build a prototype and measure gate waveforms, turn-off overshoot and case temperature under load. Compare the measured loss with the datasheet estimate and adjust the gate resistor, dead time and heatsink as needed. Measured data removes the guesswork and prevents late-stage surprises. BeiLuo's FAE team can support this validation and compare candidate modules on your operating point.

Documentation and Supply

Every Mitsubishi Electric module BeiLuo ships is factory-traceable and includes an import declaration, a certificate of origin and a RoHS compliance file. Mainstream modules are held in regional stock, so a validated design moves smoothly from prototype to production. Selecting the right module is the first step; keeping it supplied is the second, and BeiLuo supports both.