Hm... i will create my own thread for sure. Now that you present argument like that... i will take a look at my readings.Arlo1 wrote: ↑Apr 23 2019 1:41pmUhm actually the measurement I got was all over the place but almost never that low.
Amber DID NOT CALCULATE THE DEAD TIME CORRECTLY. This will cause miss readings in the resistance and all kinds of other problems. The dead time is determined by math based on all the worst case scenarios this is for prevention of a shoot through due to one transistor turning on before the other is fully off. If you are switching them to close together it will cause weird measurements. Also if you switch them to fast. Amber maybe its wise for you to start your own thread and we can try to debug your system.
I dont have a diff scope. I can only scope board signals. Or i can scope phases directly without GND.
tdead = [(t D _ OFF − t D _ ON )+ (tPDD _ MAX − tPDD _ MIN )]×1.2
I calculated deadtime with Infineon equasion from IGBT datasheet and made asumption about driver optos having the 0.25us delay. I dont know which optos Hitachi used, so this is educated guess.
On closer inspection i see i should be using toff max and ton min. Together with my assumption i arrive at 2.1uS for deadtime then.
I could try with 2us deadtime like you did. In my car i have Skyper 32pro drivers which demand 3us deadtime. But that is a different matter.