Sabvoton SVMC 72150

Vw2bugyou

1 mW
Joined
Dec 3, 2020
Messages
13
Location
Oregon
I pulled my Sabvoton apart to do some modifications ( #1 current sensing mod and #2 add a wire for 12v brake so I can possibly try variable regen ).
While doing so I saw a few things.....
It seems while there is some thermal paste on the mosfets, there isn't very much. Additionally, the heatsink block is only making contact with about 15% - 20% the outer shell of the unit. It seems the surfaces aren't perfectly true so there's an air gap.
Most importantly ( and intriguing ) though is the fact that I've found what seems to be 2 potentiometer adjustments on each of the two "inductive current sensors" that the two phase wires run through. ( why not one or three inductive sensors? )
Each of the two inductive sensors is soldered to the board with 4 contacts; +15 & -15 & out & gnd.
If I try to read what the pickups are communicating to the board I'm guessing to use a meter set to millivolts and place my probes at "out" and "gnd". Does this sound like I'm on the right track? Will I need to provide a consistent and non-varying "load" to get these readings accurately?
I can only assume a potentiometer mounted on an inductive amp probe would be used to calibrate the inductive pickup. I can't imagine why there would be two pots though.... Maybe a rough and fine calibration pot? If so I'd like to take a reading of each pickup ( I'll assume they should match ) and crank them as far as I can out of calibration while still matching each other. My guess is that it's a 50/50 that the controller will be either "turned up" or "turned down". If it ends up being the latter I can just crank the pots the other direction.
Has anyone tried twisting these pots as an alternative to jumping an additional wire over the inductive sensor to cheat the software lock these controllers keep being sent out with?
Any help is appreciated and if anyone sees a fire about to happen please jump in and stop me!
 

Attachments

  • 20210918_212244.jpg
    20210918_212244.jpg
    399 KB · Views: 761
  • 20210918_212403.jpg
    20210918_212403.jpg
    361.1 KB · Views: 760
  • 20210918_212208.jpg
    20210918_212208.jpg
    480.9 KB · Views: 760
  • 20210918_212913.jpg
    20210918_212913.jpg
    337.9 KB · Views: 760
  • 20210918_212244.jpg
    20210918_212244.jpg
    411.3 KB · Views: 760
The 2 pots on the current sensor are for "gain & offset" and used to calibrate the multiple sensors that might be fitted.

This PDF should give a fair explanation and that would be basically, don't touch them, they have nothing to do with getting more power.

https://www.melexis.com/-/media/files/documents/application-notes/current-sensors-design-guide-application-note-melexis.pdf

Hope this helps.
 
Back
Top