Question About Using EVALSTGAP4S for a 7-Level Cascaded H-Bridge Motor Drive

[Taeseong2]

I am currently considering the EVALSTGAP4S evaluation board for a laboratory prototype, and I would like to ask a few technical questions about its possible use in a motor-drive application.

My goal is to build a 7-level cascaded H-bridge (CHB) multilevel inverter for motor driving. Since the EVALSTGAP4S includes isolated gate drivers, I am wondering whether it can be used as a building block for a CHB inverter cell.

I would like to ask the following:

1. What is the practical current capability of the EVALSTGAP4S board?
   I would especially like to know the recommended continuous current range, and whether it depends on thermal conditions, switching frequency, or cooling method.
2. Would this board be suitable for use in a 7-level cascaded H-bridge multilevel inverter for motor-drive applications?
   If not, what would be the main limitations or concerns?
3. Since the board has isolated gate drivers, can multiple boards be used in a cascaded configuration with floating DC sources?
   If there are any important precautions regarding insulation, grounding, protection, or gate-drive operation in CHB applications, I would appreciate your advice.
4. If available, could you share more detailed technical information about this evaluation board?
   For example: detailed schematics, thermal design guidelines, practical current limits, layout recommendations, or any application notes related to multilevel converters or motor drives.

If this board is not suitable for this purpose, I would also appreciate any recommendation for a more appropriate ST solution for CHB-based motor-drive experiments.

Thank you in advance.

[Peter BENSCH]

Welcome @Taeseong2, to the community!

Since no one has been able to get enthusiastic about your question for quite some time now (probably because the topic has rarely come up so far), and because the personal Online Support OLS also could not help you further, it seems that your only remaining option is to persuade your local distributor, or better still, the local ST office, of your idea.

I am not necessarily an expert in this area, but the EVALSTGAP4S should in principle be suitable for this, since all secondary voltages are isolated, which should also answer your question 3.

The output current is not specified, but it can be roughly estimated based on the parameters of the gate driver MOSFETs (STL8P4LLF6 and STL8N6F7), which can each provide 20...24 mΩ and at least 8 A.

Regarding your fourth question: the schematics can be found in full and in detail in UM3153. The remaining points, namely thermal design guidelines, practical current limits, layout recommendations, or any application notes related to multilevel converters or motor drives, partly go beyond the general use of the EVAL board, but may possibly be clarified together with your distributor or the local ST office.

The more details you have for a project that may be realised in practice, the greater the likelihood of finding someone who can help you.

Does it for the moment answer your questions?

Regards
/Peter