What are the limiting factors for how much power your motor can consume? I have some ideas, but I'd like to know for certain. What is stopping us from pumping 20 kW through a 500 W motor?
Based on my experience with a Currie motor, heat seems to be a big limitation. You can increase the voltage, and the motor will spin faster, but also draw more current. The increased current will cause laminations to melt and magnets to demagnetize and in general bad things to happen. Also, I've heard of guys saying they had windings lifting off the rotor, and your maximum torque output is probably also limited by the strength of the motor shaft and the motor casing (by which you presumably mount the motor to something. So:
1. Heat dissipation
2. Magnets, if subjected to too high of a flux density
3. Physical construction
The heat dissipation is not a big deal, as you can do things to cool the motor, or simply mount a thermistor inside and keep an eye on the temperature. When temp gets too high, pull back. The magnets are rather a problem, because I can't think of any way of increasing this limit. The only thing I can think of is to use windings, instead of permanent magnets. Not sure about the ramifications of this. Probably increases size of the motor, or power consumption/efficiency. The last is simply a matter of using thick/strong enough materials.
So that brings us to power delivery systems. You want batteries with high C ratings or, simply a lot of batteries. And of course, you want as high a voltage as possible. Within limits, I suppose. I believe once you get above 100 Volts or so, things can get tricky with arcing through the air and such. Actually that probably doesn't become a problem for much higher than 100 volts... Perhaps it requires increased complexity in the circuitry, and expensive high voltage parts. Anyway, onwards. Thick wiring capable of delivering high current. And lastly, a motor controller that can deliver high voltage/current. So:
4. Batteries (High voltage/Capacity/C rating)
5. A hefty controller, capable of high voltage/current delivery
6. Thick wires.
What inspired this was the Millenium Falcon. That ship seems like it's jerry-rigged and modified to run far beyond it's original design specifications. And bursts of high speed/performance are possible only by temporarily pushing the systems past their limits, and being aware of these limits. And what to replace when things blow up Now, this is obviously conjecture. I don't know anything about the Millenium Falcon, and if anyone thinks they do then they're one of those crazed fanatics, who has trouble distinguishing between fantasy and reality. But, the thought has inspired me, and now I am curious what it would take to build an e-bike, or e-vehicle, that had the capability for short bursts of power/performance way outside original tolerances. I think with electric vehicles this is far more possible than with ICE, for example. Sure, you can say spray NOS into the engine and run it at a screaming 10,000 rpm... but in general I think they are less tolerant to being run above specifications.
Based on my experience with a Currie motor, heat seems to be a big limitation. You can increase the voltage, and the motor will spin faster, but also draw more current. The increased current will cause laminations to melt and magnets to demagnetize and in general bad things to happen. Also, I've heard of guys saying they had windings lifting off the rotor, and your maximum torque output is probably also limited by the strength of the motor shaft and the motor casing (by which you presumably mount the motor to something. So:
1. Heat dissipation
2. Magnets, if subjected to too high of a flux density
3. Physical construction
The heat dissipation is not a big deal, as you can do things to cool the motor, or simply mount a thermistor inside and keep an eye on the temperature. When temp gets too high, pull back. The magnets are rather a problem, because I can't think of any way of increasing this limit. The only thing I can think of is to use windings, instead of permanent magnets. Not sure about the ramifications of this. Probably increases size of the motor, or power consumption/efficiency. The last is simply a matter of using thick/strong enough materials.
So that brings us to power delivery systems. You want batteries with high C ratings or, simply a lot of batteries. And of course, you want as high a voltage as possible. Within limits, I suppose. I believe once you get above 100 Volts or so, things can get tricky with arcing through the air and such. Actually that probably doesn't become a problem for much higher than 100 volts... Perhaps it requires increased complexity in the circuitry, and expensive high voltage parts. Anyway, onwards. Thick wiring capable of delivering high current. And lastly, a motor controller that can deliver high voltage/current. So:
4. Batteries (High voltage/Capacity/C rating)
5. A hefty controller, capable of high voltage/current delivery
6. Thick wires.
What inspired this was the Millenium Falcon. That ship seems like it's jerry-rigged and modified to run far beyond it's original design specifications. And bursts of high speed/performance are possible only by temporarily pushing the systems past their limits, and being aware of these limits. And what to replace when things blow up Now, this is obviously conjecture. I don't know anything about the Millenium Falcon, and if anyone thinks they do then they're one of those crazed fanatics, who has trouble distinguishing between fantasy and reality. But, the thought has inspired me, and now I am curious what it would take to build an e-bike, or e-vehicle, that had the capability for short bursts of power/performance way outside original tolerances. I think with electric vehicles this is far more possible than with ICE, for example. Sure, you can say spray NOS into the engine and run it at a screaming 10,000 rpm... but in general I think they are less tolerant to being run above specifications.