IGBT module vs Full SiC power module

IGBT modules that combine Si IGBTs and FRDs (Fast Recovery Diodes) are widely used for power modules that handle large currents. We have started selling SiC power modules.

Compared to Si IGBT modules, full SiC power modules have

1. Significant reduction in switching loss
2. The higher the switching frequency, the more pronounced the overall loss reduction.

There are two big advantages.

In particular, the large switching losses caused by IGBT tail currents and FRD recovery currents have been significantly reduced by full SiC modules.

2 benefits

Now, let's take a concrete look at the merits of using a full SiC module compared to a Si IGBT module.

1.スイッチング損失を大幅に低減できる

The figure compares a 1200V/300A ROHM full SiC power module (BSM300D12P2E001) with an equivalent IGBT.

Although it is a comparison based on data sheet standard values, it shows three parameters that affect switching loss.

• Eon: Loss when switching on (including reverse recovery loss)
• Eoff: loss at switch off
• Err: Recovery loss (body diode reverse recovery loss)

As can be seen from the figure, both Eon and Eoff are significantly smaller, and as far as Err is concerned, Irr hardly flows, so it is very small.

As a result, we can see that the total switching loss is reduced by 77%.

2. The higher the switching frequency, the more pronounced the overall loss reduction.

Full SiC modules are capable of high-speed switching compared to IGBT modules. The figure shows the sum of switching loss and conduction loss at a loss simulation switching frequency of 5 kHz and 30 kHz assuming a PWM inverter.

IGBTモジュールとの比較において、5kHzでは全体損失を約22%低減できています。橙色の部分がスイッチング損失を示しており、低減された損失のほとんどはスイッチング損失です。

30kHzの条件では、まずIGBTのスイッチング損失が大幅に増加しています。これは、IGBTの高速スイッチングに対する課題であることはよく知られています。フルSiCパワーモジュールのスイッチング損失も増加していますが、その割合はIGBTモジュールの比ではありません。結果として、30kHzの条件では合計損失を約60%低減可能であることがわかります。

Third-generation SiC trench MOSFET with further reduced switching loss

ROHM has mass-produced SiC-MOSFETs with a trench structure ahead of the rest of the industry. SiC power modules have already adopted this trench structure MOSFET, further reducing switching loss compared to conventional SiC power modules.
The figure shows a comparison of switching losses of 1200V/180A and equivalent products.

• IGBT module
• Full SiC power module BSM180D12P2C101 using second-generation DMOS structure SiC-MOSFET
• BSM180D12P3C007 using 3rd generation trench structure MOSFET

The switching loss is the result of comparison based on the standard value of the data sheet.

Compared to IGBTs, the 2nd generation reduces switching losses by approximately 60%, and the 3rd generation reduces switching losses by approximately 42% compared to the 2nd generation. It is

Application example

• Power inverter for industrial equipment
• PV inverter
• motor drive

At the end

Full-SiC power modules can significantly reduce switching loss compared to IGBT modules, and the higher the switching frequency, the greater the difference in loss from IGBT modules. Full-SiC power modules enable high-speed switching while greatly reducing losses.

Full-SiC power modules will continue to evolve further toward larger capacities.

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