Hi, This is Ranjith, Im trying to develop a custom Driver based on VESC 75_300 schematics.
There is a major issue im facing right now, which i couldn't figure it out by myself, my hardware design has two boards,
- The Driver unit board has the mosfet, shunt, temp sensor and the signal connector that reaches the second board (Control Unit).
- The Control unit board has the rest of the components.
In this design we are using a different mosfet which is IPT029N08N5 instead of IRF7759L2PbF.
So the Issues are ;
- When ever we power the board individually, they were working fine, but when we connect the signals from the Control board to the Driver Board, the Mosfet are bursting out.
- When we power the Control board, we see a variation in the dutycycle and the board is turned on with the driving led(Green). This happens even before turning.
Check to see if you have Offset calibration at boot enabled in the FOC configuration? If it is, the firmware send short pulses to the drivers to calibrate offsets and if you have your current sensing values not set up correctly, you can fry the mosfets easily. During the development stage and pretty much when turning on a freshly made controller for the first time, you want to make sure it doesn't turn on drivers immediately at the boot time until you check everything is set up correctly.
NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)
Hi vadicus, Thanks for your feedback.
This is exactly whats happening in my situation, the MOSFETs are getting fried once the MCU turns on (bootsup). and there is a variation in the duty cycle. I just don't know why there is duty cycle change and the green lights getting turned on, In this case I haven't tuned a motor or provided any external inputs like throttle etc.
Sorry, Right now im bit vague in this explanation, Im trying to figure out the issue, thats occuring here, Could you able to help me with it.
Please read carefully my previous message- it sounds like you either missed the important detail I already provided. The enabled Offset calibration at boot will cause the phase PWMs to pulse, you may want to disabled them before connecting the motor:
NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)
I have solved the problem of mosfets getting failed, its because i have selected wrong components in my previous design, it works now well and good, but still I have a offset in current measurement, while performing load test, I have noticed that the measured current from clamp meter is 96.8A DC, but what I have read from the VESC Tool is 124.9A DC. what might be the cause, is there a way to correct this offset from the VESC Tool ?