HAS310M17BM3 gate driver for Railway application

littleBlue

Hello,

I'm considering using HAS310M17BM3 SiC module for tram auxiliary converter application. However, I have difficulties choosing an adequate gate driver for stringent insulation requirements. I was considering using CGD1700HB2P-BM-REV01 gate driver evaluation board, however, after seeing that gate drive chip on that board AD ADUM4146 has creepage distance of 8.3mm, I have hard time justifying even trying a simple double pulse test.

Also, seeing that MGJ2D121505SC DC/DC converter is having only 2mm creepage/clearance between primary and secondary, it is even worse.

According to IEC EN 50124, I need a driver that would satisfy PD3, OV3 reinforced insulation at 600 Vdc nominal tram line voltage.

That corresponds to creepage distance of 18,1 mm for Material group 1 or 20,12 mm for Material group 2 between primary low voltage PWM signal and secondary high voltage side.

Is there a solution (possibly using double insulation) and how to realize that type of gate driver using suggested BOM from CGD1700HB2P-BM-REV01 evaluation board.

Thank you.

Forum_Moderator

Thank you for your post, it has been approved and we will respond as soon as possible.

ChrisN

Hello littleBlue,

We typically design our gate drivers to the creepage requirements outlined in UL 61800-5-1, which is largely harmonized with IEC 61800-5-1. These gate drivers are well suited for laboratory testing and early design activities. We use these gate drivers for our internal testing of these modules. You can use these gate drivers safely for double pulse testing.

These gate drivers are designed to be used in laboratory environments and are not intended to operate in an end application. To achieve your strict isolation requirements, you may need to develop a custom solution, though you can still adopt the design practices used in the CGD1700HB2P-BM gate drivers (outside of the isolation). For very high isolation, some designers use fiber option isolation such as the Broadcom AFBR-2634Z or use a larger footprint isolators such as the Texas Instruments ISO7841F.

Although I am not directly familiar with the IEC EN 50124 standard, I would recommend reviewing the creepage requirements that you identified to ensure the right ones were selected. In creepage standards I have reviewed, the creepage requirement is typically <10 mm at these voltages, though I recognize this standard could be more stringent. Please also consider the following items which may decrease the creepage requirement. First, many isolated gate driver components use high-CTI materials such that the creepage requirements of the part are not as stringent. Second, printed circuit board components often have different creepage requirements in standards than other materials. Third, you can consider coating the gate driver board with electrically insulating material to potentially reduce the creepage/clearance requirement.

Thanks,

Chris N.