High Voltage Forum

General electronics => Beginners => Topic started by: L_Mangold on May 15, 2019, 12:42:46 AM

Title: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
Post by: L_Mangold on May 15, 2019, 12:42:46 AM

Hello everyone,

I wanted to get a few other peoples' input on probing techniques for troubleshooting (DR)SSTC H-bridge circuitry. Currently, I have been using a used analogue CRT scope from Tektronics for probing pretty much everything from my driver to the actual power side of the coil(s) that I've been working on. The benefit of the analogue scope has included being able to see very short/transient spikes, as well as the fact that it has an add feature that allows for differential (I believe) measurements. I've been able to tune my primary, probe current waveforms, and even turn phase lead on the driver, but I've been nervous about taking any measurements when powering the bridge via mains. I just bought a Hantek digital storage scope, and an additional 1-100X probe so my old scope will now be my back-up one and provide an additional 2 channels in case I need more than 2 for one test.

My question is simply to inquire as to how everyone else probes their bridge; particularly probing the high side IGBT's and tuning phase lead, and whether or not you use a high voltage differential probe.

Thank you kindly in advance!

Title: Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
Post by: Mads Barnkob on May 15, 2019, 10:08:11 AM

I use my DSO1054z with a range of different Pearson current monitors and a Tektronix P5100 differential probe for up to 1100V isolated measurements. I also have a 2ch Tektronix A6909 isolator for up to 600V.

I try to follow the guide on measurements found here: https://highvoltageforum.net/index.php?topic=2.0

Quote

Guides and tutorials
https://highvoltageforum.net/index.php?topic=111.0 - Tektronix 30-page guide to do CORRECT measurements on SMPS and Inverters

Title: Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
Post by: Teravolt on May 20, 2019, 06:33:49 PM

invest in a isolation transformer so you can connect your scope common to your power sources common. reserch so you understand what you doing. I just use a dual winding 120 to 120 transformer. it does not have to be a expensive topaz transformer just something to seperate your mains refrance to ground. if you have 220 the same applies. it will be cheaper than a diferencial probe

Title: Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
Post by: Mads Barnkob on May 21, 2019, 09:51:27 PM

Dave from EEVblog made a video long ago on oscilloscope grounding

Title: Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
Post by: L_Mangold on June 01, 2019, 12:23:13 AM

I love Dave from EEVblog. Thank you very much for the input friends!