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<blockquote data-quote="Prashant Kumar" data-source="post: 740012"><h4>Basic Technical Details</h4>The driver is basically a DC solar charge controller, it&#039;s used in solar street lights, it requires a battery and panel. This driver uses the Buck-Boost Topology. At night it behaves as a Boost converter from battery to the lamp load. In sunlight - when charging - it behaves as a Buck converter.<ul>
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Load - 12W 
 
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Battery - Li-Po4 (12.8v) 
 
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Panel - 75W (21VDC) 
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</ul><h4>Problem</h4>To cope with thunderstorms and other upsets, we need to test the driver circuit to withstand overvoltages on the connections to battery and load.The test procedure uses a 1000V pulse, of either polarity, at the panel input side.Our initial choice of circuit protection is a MOV as shown in the circuit diagram below. The MOV part# is CVR 40D14. With this MOV, the circuit failed at a positive surge of 750 volts and also failed at a negative surge of 500 volts. The mosfets are rated 40V maximum.<h4>Question</h4>How to choose the right protection circuitry to pass 1000 volts surge ?If you want any other technical details please let me know.<a href="https://i.sstatic.net/UsMjH.jpg"><img src="https://i.sstatic.net/UsMjH.jpg" alt="a fragment of the schematic of the driver circuit, showing the buck-boost mosfets, and the location of the MOV" class="fr-fic fr-dii fr-draggable " style="" /></a></blockquote>

[QUOTE="Prashant Kumar, post: 740012"] [HEADING=3]Basic Technical Details[/HEADING] The driver is basically a DC solar charge controller, it's used in solar street lights, it requires a battery and panel. This driver uses the Buck-Boost Topology. At night it behaves as a Boost converter from battery to the lamp load. In sunlight - when charging - it behaves as a Buck converter. [LIST] [*] Load - 12W [*] Battery - Li-Po4 (12.8v) [*] Panel - 75W (21VDC) [/LIST] [HEADING=3]Problem[/HEADING] To cope with thunderstorms and other upsets, we need to test the driver circuit to withstand overvoltages on the connections to battery and load. The test procedure uses a 1000V pulse, of either polarity, at the panel input side. Our initial choice of circuit protection is a MOV as shown in the circuit diagram below. The MOV part# is CVR 40D14. With this MOV, the circuit failed at a positive surge of 750 volts and also failed at a negative surge of 500 volts. The mosfets are rated 40V maximum. [HEADING=3]Question[/HEADING] How to choose the right protection circuitry to pass 1000 volts surge ? If you want any other technical details please let me know. [URL='https://i.sstatic.net/UsMjH.jpg'][IMG alt="a fragment of the schematic of the driver circuit, showing the buck-boost mosfets, and the location of the MOV"]https://i.sstatic.net/UsMjH.jpg[/IMG][/URL] [/QUOTE]

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