A few notes about the ideas discussed here, as my business is designing electronics:
1) If the module has 6 individual LED chips you will have to supply them by individual drivers. Connected in parallel a LED which heats up will draw more current from the given voltage resulting in even more heat dissipated until is's gone
.
2) I would not recommend to use a step up design if you want to get flicker free light. Without lots of filtering at the output a step up will produce strong flicker at it's PWM frequency.
3) Power dissipation in
step up converter. The MOSFET or IGBT in an step up converter has to handle the input current and the output voltage. Thus converting 1500 W from 12 to 36 V will have an input current of 125 A. Power distribution is split in two components, static and dynamic loss.
Static loss can be estimated with the ON resistance RDSON for MOSFETs to be about (InputCurrent)^2*RDSON*(Vin/Vout). For the IXIS device referenced in an earlier post this would be about 125^2*0.0055*12/36 = 29 W (quite fine).
Using an IGBT this estimate would be saturation voltage VCEsat (typically in range of 2 V) * input current * Vin/Vout, resulting in about 83 W (need for good cooling).
Dynamic loss is caused by switching and could be estimated for both with SwitchingTime*Vout*InputCurrent*SwitchingFrequency. Trying to run the IXIS MOSFET at 125 kHz this leads to 200ns*36V*125A*125000 = 112.5 W.
To cool a total of >150 Wwill need water cooling or a pretty big heatsink for the MOSFET. Note the 1500 W shown in the datasheet is the maximum power dissipation if you manage to keep the case temperature at 25°C!
More notes:
a) As you can guess from the dynamic loss estimate above, switching at 5 MHz will definitely not work at this load.
b) Gate current during switching will be several A, so you need a good gate driver circuit to achieve the switching times shown in the datasheet.
c) In general switching converters will produce high electromagnetic noise emission. At this power there is a good chance you run into serious issues up to disturbing radio, TV, mobile and WiFi reception.
d) Stray inductance in the circuit caused by even short wires might produce strange voltage peaks which could easy destroy your electronics.
e) As of the voltage/current characteristic of a LED you won't get stable output current/power unless you put in a control circuit. Without this active control circuit there is a good chance you overload your LED with a slight change in PWM duty cycle. Warning: You won't get a linear relation between PWM duty and output current/power! The actual will be more like a threshold where the output starts to increase pretty steep without current control.
Conclusion: Don't try to build your own circuit unless you are familar with design of power electronics.