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I'm currently an electrical engineering student working on building a 3 degree of freedom motion simulator using three 90V DC Stepper Motors. Each motor can draw up to 5 A so I need to find or build a 90V DC power supply that can handle up to 15 A (1.35 kW). I've tried looking around for an already built power supply that I could buy but for this amount of power these become very expensive (~$3000). I'm working for a client whom recommended that I use a Dual IGBTMOD H-Series Module (Datasheet: http://www.pwrx.com/pwrx/docs/cm50dy-12h.pdf) to convert 120 VAC to 90VDC. Schematic for Dual IGBTMOD H-Series Module

The picture above shows the schematic for the module and I've tried searching for circuit diagrams of power supplies using similar modules and but I haven't been able to figure out how these work. From my understanding I imagine that 120 VAC would connect to C1 and E2 terminals and a PWM signal would be fed to the gates G1 and G2 to get the desired output at C2E1. However this is just speculation and I'm not sure if what I'm thinking is completely wrong or if there may be a better solution altogether. Any help would be greatly appreciated, thanks.

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  • \$\begingroup\$ It is pretty much never cheaper to design and build a small quantity of something if the item is also commercially available. However, you may have not really looked hard enough. You don't need a flexible, programmable bench type supply. You just need something that can put out 15 amps at 90V. I would personally be a bit scared of designing a 15A, 90V supply for a customer, and I think you should be scared of it, too. Sure, I could cobble something together for my own use. But this type of supply is a specialty design area. \$\endgroup\$ – mkeith Mar 2 '16 at 20:36
  • \$\begingroup\$ This is a speed control (it is a power supply with tachometer feedback) that can work up to 90V and 15A. zoro.com/… \$\endgroup\$ – mkeith Mar 2 '16 at 20:41
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Generally, unless you really need to it is better to buy power supplies.

To answer your question, you could build an efficient rectifier out of these, you would spend some time designing a circuit to switch the IGBT's at the appropriate time, and if they don't, then they blow up. An easier way is just using schottky diodes, you would have to have some monster caps to filter the rectified voltage. If you need to parallel the diodes to get the current you need.

I think a better way is changing your design at the system level, the steppers draw 5A, are they doing this continuously? No. So you may not need the total 5A. Even if you did need all 5A, Power supplies are available that can be connected in series. For one motor two 48v 5A power supplies could be used (and most of them come with a regulator that you could bump the power down to 45V). You would need two supplies for each axis, they run at about 100$ for each supply. 600$ for the whole system.

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  • \$\begingroup\$ Steppers tend to draw rated current when stationary - but at much less than full voltage. So you probably DO need the full 15A - but possibly only at 12 or 24V with a 5A 90V supply for high speed stepping. \$\endgroup\$ – Brian Drummond Mar 2 '16 at 21:24
  • \$\begingroup\$ I know how they work, but if the application doesn't need holding torque then you could derate the power supply. \$\endgroup\$ – Voltage Spike Mar 2 '16 at 21:26
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You could just buy 2 identical say 48VDC 15Amp supplies .They will be cheap because they are really a commodity item now. Now adjust them to do 45V and connect in series.That is an easy 90V.

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