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Driving Peltier with VNH5019A-E

Question asked by van_buskirk.steven on Jan 13, 2015
Latest reply on Feb 12, 2015 by brugora.marco
I am having trouble driving a peltier device with the VNH5019. The channel config. in the scope pictures is as follows:1. Vin to H-bridge2. PWM logic in3. A leg out4. B leg outGoodDrive.bmp shows what's supposed to happen. When the 50% 10kHz PWM pulses on 12 V is applied to the peltier, which should draw up to 12 A. But sometimes it turns out like in BadDrive.bmp where the peltier drive is cutoff prematurely, and then the next several PWM cycles are skipped. It seems to depend on the exact instance of the H-Bridge used, peltier used, or temperature gradient of the peltier; i.e. I think something is just right on the edge of working.
I put a 27 uH inductor on both legs, and the situation improved a little as in L.bmp. Not sure what the problem is. Any thoughts or ideas would be much appreciated.