class: center, middle # EE-463 STATIC POWER CONVERSION-I # Snubbers and Protection Circuits ## Ozan Keysan ## [keysan.me](http://keysan.me) ### Office: C-113 <span class="meta">•</span> Tel: 210 7586 --- # What is a Snubber? -- <img src="https://images-na.ssl-images-amazon.com/images/I/61kukXLm4PL._SL1100_.jpg" alt="Drawing" style="width: 500px;"/> --- # What is a Snubber? <img src="https://images-na.ssl-images-amazon.com/images/I/71de4v85pVL._SL1500_.jpg" alt="Drawing" style="width: 500px;"/> --- ## Why do we need snubbers in power electronics? -- - ## Limit voltage transients -- - ## Limit dv/dt to protect devices and prevent accidental turn-on -- - ## Reduction of switching losses -- - ## Reduce EMI -- - ## Prevent arcing in mechanical relays etc. #### [More info](https://www.digikey.com/en/articles/resistor-capacitor-rc-snubber-design-for-power-switches) --- # Reasons for Transients -- ## Mostly due to stray/parasitic inductances -- - ## Device inductance -- - ## PCB or line inductance --- # RC Snubber -- <img src="https://upload.wikimedia.org/wikipedia/commons/8/88/RC_Snubber_%28Model%29.PNG" alt="Drawing" style="width: 400px;"/> --- # RC Snubber -- <img src="https://upload.wikimedia.org/wikipedia/commons/e/ec/Snubber.jpg" alt="Drawing" style="width: 750px;"/> --- # Reasons to Use Snubber -- ## Common Parasitic Components -- ### Example: [Synchronous Buck](http://www.electronicdesign.com/analog/how-control-emi-synchronous-buck-converters) <img src="./images/ee463/sync_buck.png" alt="Drawing" style="width: 500px;"/> --- ## Synchronous Buck with Parasitic Components <img src="./images/ee463/sync_buck2.png" alt="Drawing" style="width: 500px;"/> --- ## Voltage Waveforms (For [IGBT](https://www.semikron.com/dl/service-support/downloads/download/semikron-application-note-igbt-peak-voltage-measurement-and-snubber-capacitor-specification-en-2008-03-17-rev-00/)) <img src="./images/ee463/snubber_voltage.png" alt="Drawing" style="width: 550px;"/> --- # Equivalent Circuit for IGBT <img src="./images/ee463/igbt_parasitic.png" alt="Drawing" style="width: 800px;"/> --- # Snubber Equations <img src="./images/ee463/igbt_snubber_equations.png" alt="Drawing" style="width: 800px;"/> --- # RC Snubber Applications Notes -- - ## [Designing RC Snubber Networks](https://assets.nexperia.com/documents/application-note/AN11160.pdf) - ## [Calculate R-C Snubber in 7 Steps](https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/05/05/calculate-an-r-c-snubber-in-seven-steps) - ## [Snubber Circuit for Buck Converter](http://rohmfs.rohm.com/en/products/databook/applinote/ic/power/switching_regulator/buck_snubber_app-e.pdf) - ## [IGBT Snubber Capacitors](https://www.semikron.com/dl/service-support/downloads/download/semikron-application-note-igbt-peak-voltage-measurement-and-snubber-capacitor-specification-en-2008-03-17-rev-00/) --- # Diode Snubbers -- ## Freewheeling diode is a very basic snubber <img src="https://gordon831.files.wordpress.com/2013/08/freewheeldiode1.png" alt="Drawing" style="width: 750px;"/> --- # Diode Snubbers: RCD Snubber -- <img src="./images/ee463/rcd_snubber.jpg" alt="Drawing" style="width: 400px;"/> --- # Diode Snubbers: RCD Snubber -- ### Flyback Converter (Wait until EE464) with RCD Snubber -- <img src="https://upload.wikimedia.org/wikipedia/commons/3/34/Flyback_w_snubber.svg" alt="Drawing" style="width: 700px;"/> #### Absorbs the current in the leakage inductor #### [RCD Application Note](https://www.fairchildsemi.com/application-notes/AN/AN-4147.pdf), [RCD Design](http://basicelectronic.blogspot.com.tr/2009/03/mosfet-rcd-snubber-circuit-design.html) --- ## You can download this presentation from: [keysan.me/ee463](http://keysan.me/ee463)