Hello,
I'm currently drooling at joby's JM1S motor with a 17kV (500V) wind. I see the extreme amperage normally needed to produce huge power as inefficient and expencive. Kicking it up a notch to where igbts are effective (i.e - not 200v range) and using a bidirectional dc/dc converter would imo result in a better product. Instead of using 6*x mosfets for low voltage phase current controll - you would only need one huge one for the dc/dc converter.
Spin off: Using the dc/dc circuit already there, adding some components to charge from 220Vac (maybe using Vpp for 440V rectified) without a big bulky charger would be nice.
Dc/dc converter, i'm blank here as to what circuit to go for; but the stuff I've read so far indicates that power density of such a converter should be able to reach 10kW/kg. Total added weight should not be much more than 2 kgs for this.
Controller. I'm thinking of a master/slave setup between a atmel AVR and a atmel FPGA. Motor controll will be controlled by the fpga (~3ns reaction time) with simple logic gates and a pwm input. The avr will handle all the inputs and monitor the state of everything. Igbt's: again, I need a lot of input.
Encoder: One alternative is using bemf for the high speed electrical rpm (200 000 at 9000rpm speed). The drawback is off the line start, you need to use pedals to get up to speed. Hall elements are suceptible to noise - I find photodiodes being a nice alternative. At ~2 dollars each they are cheap, with a 2,5 ns rise and fall time. There may be better alternatives when taking implementation to a fpga into consideration (this was the first alternative I found).
Yes, I know joby motors are rated for continous use in a aircraft (=lots of airflow). What do people think of the idea? Please chime in with your pros and cons
I'm currently drooling at joby's JM1S motor with a 17kV (500V) wind. I see the extreme amperage normally needed to produce huge power as inefficient and expencive. Kicking it up a notch to where igbts are effective (i.e - not 200v range) and using a bidirectional dc/dc converter would imo result in a better product. Instead of using 6*x mosfets for low voltage phase current controll - you would only need one huge one for the dc/dc converter.
Spin off: Using the dc/dc circuit already there, adding some components to charge from 220Vac (maybe using Vpp for 440V rectified) without a big bulky charger would be nice.
Dc/dc converter, i'm blank here as to what circuit to go for; but the stuff I've read so far indicates that power density of such a converter should be able to reach 10kW/kg. Total added weight should not be much more than 2 kgs for this.
Controller. I'm thinking of a master/slave setup between a atmel AVR and a atmel FPGA. Motor controll will be controlled by the fpga (~3ns reaction time) with simple logic gates and a pwm input. The avr will handle all the inputs and monitor the state of everything. Igbt's: again, I need a lot of input.
Encoder: One alternative is using bemf for the high speed electrical rpm (200 000 at 9000rpm speed). The drawback is off the line start, you need to use pedals to get up to speed. Hall elements are suceptible to noise - I find photodiodes being a nice alternative. At ~2 dollars each they are cheap, with a 2,5 ns rise and fall time. There may be better alternatives when taking implementation to a fpga into consideration (this was the first alternative I found).
Yes, I know joby motors are rated for continous use in a aircraft (=lots of airflow). What do people think of the idea? Please chime in with your pros and cons
