On 03/02/2012 11:38 AM, Kirk Wallace wrote: > (First Message may have failed due to attachment too big) > > Attached is my first pass at an IRAMS circuit. It's pretty much a copy > of the IRF datasheet example. The plan is to hook up the digital signals > to an FPGA card, Pluto-P if I can find it, or 5i25 if I sell something > on eBay. The analog signals are an unknown for now. IRF seems to > recommend using a ceramic capacitor with each electrolytic, I need to > learn more about this as well as chose a size for the motor input caps. > Any suggestions are welcome.
Kirk, What DC bus voltage are you planning to feed to the IRAMS module? I would think a low-ESR capacitor of 1 or 2 microfarad would be desirable across the DC bus, located right next to the IRAMS module. A low-ESR film capacitor should work about as well as a ceramic and may be easier/cheaper to find if the voltage is very high. Motor input caps? Are these the 2.2uF caps in your schematic? I think these are bootstrap capacitors, used to generate a voltage inside the chip to drive the gates of the top switches. Have a look here: http://www.irf.com/technical-info/designtp/dt04-4.pdf Their minimum capacitance depends on how much voltage you have on your DC bus, what your switching frequency is going to be, and what minimum duty cycle you plan to have. Are any of these things known? Grounding is key to using these modules. Especially at high voltage. For breadboarding, try to do it on a board with a copper plane. Without this, it's not hard to get switching spikes across ground lines which are large enough to turn a logic 1 into a logic 0. When that happens, things can go bang very quickly. Karl ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
