I'm preparing to replace the power stage + breadboard with a single controller box. The last parts should arrive next week. It's almost fully assembled though, so I thought I'd post some pics.
), will do long and severe gravel uphill hauls, heavy trail duty etc under constant battery current limiting without getting worringly hot to the touch. It will be subject to testing to find out how much further a single row of TO-247s such as this can be taken.
Here is a shot at an analytical way to predict how far it could be safely taken. Without any forced cooling, ie a normal e-bike controller box with some wind, assume the mosfet can continuously handle half of the datasheet current, in this case 195/2 =~ 100A. Continuously meaning at a time scale several decades higher than what is used in the Safe Operating Area curve, perhaps several tens of seconds of very steep climbing or similar.
Consider further that the device is conducting 66% of the time; 33% as on-time, 33% as diode and 33% off. This means it could actually take the equivalent current of 100/0.66 =~ 150A during its on/diode time, since it gets to "rest" the remaining 33%. The battery current needed to drive that phase at 150A is I_batt = I_mosfet * (duty cycle). (This is making an analogy of the motor phase to a buck converter).
The load on the mosfet is at its highest during startup or low speed climbing, where they are at risk of blowing. The duty cycle is perhaps 10-20%, so any battery current would result in a 5-10 times higher current in the mosfet (according to the buck converter formula above). Assuming one were to stay in this mode continuously - as for example during a very steep climb - a safe battery current cap would then be 150 / (5-10) = 15-30A.
This lines up ok with what I know from a pair of Golden Motor controllers I once owned. They were capped at 20A battery current, using a single row of TO-220s. A reasonable cap for TO-247 - from a longevity perspective - would then be somewhere above that, perhaps at 30-40A. Testing will tell.
The software has been updated to enable higher rpms. It will now spin a seven pole-pair motor up to 13 000 rpm (90 000 e-rpm). This however has little practical meaning, since I'm using only 10000 rpm.
The present controller - equal to the new one in most aspects - is running at 62V(16S)/25A, so about 1500W. It's very happy at this level (as is the driver