October 5, 2022


Empowering People

Using IGBT Modules to Improve System Efficiency

With the recent push for high-efficiency systems from both the broader industry sectors and the government, the semiconductor industry is responding with optimized power electronics focusing on increased reliability and operating performance.

There are two types of losses in an  IGBT module:

  • Conduction
  • Switching

It is well understood that efforts to reduce conduction losses at a given voltage will result in a compromise in switching losses, and vice versa. As a result, no single module optimized for a specific operation can provide a one-stop solution for a variety of application requirements across the operating window.

Traditionally, semiconductor manufacturers offer a single IGBT power module at any voltage level to fit a wide range of applications when operating under nominal conditions. This method restricts design flexibility and optimization from one inverter unit to the next and, in some topologies, even within a single inverter unit.

Igbts With Different Operating Frequencies Aid In Increasing Efficiency

Dynex’s new products demonstrate how providing  IGBT modules optimized for different operating frequencies helps increase overall system efficiency. On a 3-L NPC inverter topology, selecting two different modules per phase, as opposed to a single module for all slots, results in a significant efficiency improvement.

The IGBTs T1 to T4 contribute the majority of the losses in the 3L NPC topology, as shown in Figure 1 right, followed by the NPC diodes D5 and D6. Losses in D1 to D4 usually contribute to a very low overall share.

T1 and T4’s overall losses are dominated by switching losses, whereas T2 and T3 are dominated by conduction losses.

As a result, choosing the high frequency optimized IGBT variant DIM1500ESM33-MF (referred to as MF from here onwards) for T1 and T4, and the conduction optimized DIM1500ESM33-MS (referred to as MS from here onwards) for T2 and T3, provides improved overall efficiencies simulated across the frequency spectrum when compared to any single IGBT optimized for an individual operation.

Content of a 3L NPC Phase Leg.
Figure 1: A 3L NPC Phase Leg’s Contents.
Semiconductor Power losses per phase (W) Vs. Frequency (Hz) MS vs MF and optimised use of MF + MS.
Figure 2a: Semiconductor power losses per phase (W) vs. frequency (Hz), MS vs MF, and optimal use of MF + MS.

Figure 2a compares the losses per phase of Dynex MS and MF variant modules and the MS + MF optimized combination. Figure 2b overlays the same data for four competing modules for further comparison.

Comparison of Power Losses using Dynex MS and MF variant modules vs modules from four competitors.
Figure 2b: Power loss comparison between Dynex MS and MF variant modules and modules from four competitors.

Dynex IGBT for Conduction and Switching

Under 550Hz operation, the Dynex IGBT optimized for conduction (DIM1500ESM33-MS) outperforms competitor IGBT power modules designed as average switching and conduction performers.

Above 550Hz operations, Dynex’s switching-optimized variant (DIM1500ESM33-MF) outperforms competing modules, making the MS and MF variants ideal choices for low and high-frequency operation, respectively. Combining MS+MF modules with care optimizes system performance even further, demonstrating greater superiority in Dynex IGBT performance versus the established competition.

With ever-increasing standards for higher efficiency systems, this demonstrates that designers should consider optimizing not only from system to system, but also within different slots of a phase in the system, where applicable.