For my next project at my workplace I am looking for an oscilloscope which gives me good support in measuring the losses in one of the half-bridge switches over one commutation period. The last time I did this the measurement results were far off from reality as the scope just added switching and conduction losses where the letter ones were totally wrong due to offset errors of the voltage probe. Furthermore it was not possible to select a certain interval over which the losses should be averaged. In short, I am looking for something that can:
- Distinguish between switching and conduction losses
- Calculate conduction losses based on an Rdson I enter (or even reliably calculate it)
- Average losses in a specially defined interval
- Make calculations based on all acquired samples within the interval, not just of those printed on the screen
I addition I hope to be able to calculate the junction temperature of the switches my measuring the forward voltage drop of the body diode at certain current values.
The commutation frequency of my signal is between 50 - 150 Hz, PWM frequency is 10kHz, voltage rise and fall times < 100ns. Off voltage on the switch is 30V, on voltage <100mV.
At the moment I am considering either a LeCroy HDO4000 or a Keysight 4000 S-Series oscilloscope with the additional power measurement software. If the software works the way I hope, this will save me a lot of time during development. The manuals of these packages however only show measurements performed on DC-DC converters, nothing on DC-AC converters.
Does anyone of you have experiences with these tools or other recommendations?