hmm. i'm just wondering how you cope with the switching losses from running with what I assume is a 100+khz pwm frequency (if I read the rcgroups thread right)...
I'm so happy and impressed with the circuit. This test was run at 150KHz. They're very fast FETs, and we're driving almost 4 amps into the gates. There are 3 power sources -- logic, gate and power. Even without the primary power connected, when something goes wrong, it can emit a LOT of magic smoke!
yeah, atm i'm running UC3710 6 amp gate drives. (2a per fet) everything seems to be holding up fine at (current limited) 200A for 5 minutes without undue heating :) only issue is coping with the ripple currents which are eating my caps, as i can't be arsed to program a full sinusoidal control. ah well. besides, efficiency isn't the aim here - more reliability, as this controller is being done for a couple of combat robotics teams who've been through 21 brushless escs in a year between them :-P
Quite awesome. I have overhauled the circuit a few times because of reliability issues. One major concern is making sure the H-bridge is not in conflict, even if the microcontroller glitches. We've done various driver-to-fet ratios. The final driver circuit uses 2 amps per FET, 36 FETs.
Layout is important. Get you your capacitors as close to the FETs as possible. You can see in the video -- Many low-ESR caps are sandwiched between the rows of FETs.
im using the arduino to generate my pulses and the way i configured the motor was to drive on ONLY ONE COIL OUT OF 3. i have been thinking about a plane or some such but not really got a decent schematic for a driver board.
The circuit is just 3 H-bridges. The rest is microprocessor-controlled. I use comparators to compare individual leg voltage to the average leg voltage in order to know when to shift the phase.
Holy crap! That's impressive.
youtubasoarus 1 year ago
Good job guys! Very interesting, thanks!
mikespulligan 2 years ago
hmm. i'm just wondering how you cope with the switching losses from running with what I assume is a 100+khz pwm frequency (if I read the rcgroups thread right)...
thearisen 2 years ago
I'm so happy and impressed with the circuit. This test was run at 150KHz. They're very fast FETs, and we're driving almost 4 amps into the gates. There are 3 power sources -- logic, gate and power. Even without the primary power connected, when something goes wrong, it can emit a LOT of magic smoke!
KippTheKidd 2 years ago
yeah, atm i'm running UC3710 6 amp gate drives. (2a per fet) everything seems to be holding up fine at (current limited) 200A for 5 minutes without undue heating :) only issue is coping with the ripple currents which are eating my caps, as i can't be arsed to program a full sinusoidal control. ah well. besides, efficiency isn't the aim here - more reliability, as this controller is being done for a couple of combat robotics teams who've been through 21 brushless escs in a year between them :-P
thearisen 2 years ago
Quite awesome. I have overhauled the circuit a few times because of reliability issues. One major concern is making sure the H-bridge is not in conflict, even if the microcontroller glitches. We've done various driver-to-fet ratios. The final driver circuit uses 2 amps per FET, 36 FETs.
Layout is important. Get you your capacitors as close to the FETs as possible. You can see in the video -- Many low-ESR caps are sandwiched between the rows of FETs.
Good luck with the new ESC!
KippTheKidd 2 years ago
do you have a schematic??
i have been experimenting with these motors too.
im using the arduino to generate my pulses and the way i configured the motor was to drive on ONLY ONE COIL OUT OF 3. i have been thinking about a plane or some such but not really got a decent schematic for a driver board.
best regards
fl4sh134 2 years ago
The circuit is just 3 H-bridges. The rest is microprocessor-controlled. I use comparators to compare individual leg voltage to the average leg voltage in order to know when to shift the phase.
KippTheKidd 2 years ago
ok so do you have "your" circuit schematic? the microcontroller part is where i will use the arduino and pwm.
fl4sh134 2 years ago
Nope, it's a business venture. Can't share it, sorry.
KippTheKidd 2 years ago
What's your background? Do you work in the electrical type field?
club1075 3 years ago
I'm a software engineer for Welch Allyn. Prior, I designed microcontroller-based remote-controlled airplane products.
KippTheKidd 3 years ago
WOW THATS AWSOME!
102skull3 3 years ago
hows leo doing?
Maxrock9 3 years ago
Kewl! OK... so I'm thinking this is the first scene of "Primer". Good job Kipp!
rodspencer 3 years ago