DC Brushless Motor Controller

This is a motor controller I'm designing to power my electric motorcycle. Correction to video: At full speed, it was drawing 53 amps; approximately 1.5 horsepower.

Category:

Science & Technology

Tags:

• electric
• motorcycle
• ultralight
• controller

[baboracus]

How do you select which capacitors or varistors that will eliminate the power factor? Also, if the motor is rated at something like "115V 60Hz 7.1A" and the resistance across it's terminals is 2.5 ohms. Would the theoretical inductance be:

|Z| = 115/7.1

sqrt(2.5^2 + 2*pi*60*L^2) = 16.20

L = sqrt(16.2^2 - 2.5^2) / (2*pi*60)

L = 42 mH

Are you using the microcontroller to put 3 phase square wave into the MOSFETS or transistors? Are you varying the current, voltage or frequency?

[KippTheKidd]

@baboracus This isn't an AC motor - it's a DC brushless... can't help you with inductance calculations of an AC motor.

Unlike an AC motor, the frequency is completely adaptive because the controller is always reading the motor and applying a field that is a few degrees ahead of the rotor position. The controller doesn't care about resistance or inductance, and can run an ironless (super low inductance) motor.

[KippTheKidd]

@baboracus The micro chooses which FETs apply a field slightly ahead of the motor position and applies a 100kHz center-balanced PWM. Variations in speed, voltage, current and frequency are side-effects of motor resistance, inductance, load and the PWM duty cycle.

[KippTheKidd]

Probably not. You'd want about 50HP on a drifter. This motor can put out about 10 (it was only 1.5 in this video - I have another vid that's 9.5HP)

[nuriqa88]

where can I get Brushless DC motor?I need to do A low cost Brusless Dc motor controller using 8 bit microcontroller...

[KippTheKidd]

@nuriqa88 You don't want something this big though, it requires gigantic transistors. Usually, you'd want something with an encoder; making one that uses back-EMF is very difficult. I don't know where you can get one, but you could try searching for "DC Brushless Motor with encoder" on Google Shopping.

[KippTheKidd]

@chilidress Sorry, contains trade secrets. Schematic is huge. The circuit also has a CPLD and an MCU - lots of code. There are simpler controllers you could probably look up online.

[killer00630]

Would this be powerful enough to lift an ultralight plane?

[stimps90]

Cool! Thanks for that, if i can find a siutable circuit design i might get one! Would be perfect to start the jet

[KippTheKidd]

@stimps90 Try hobbyking. It's a Turnigy 180 7000W motor. Cheap too - only around $100. However, being a brushless motor, you'll need a controller (which is what I was developing in this video), and they can be a bit more expensive. The controller that was designed for this motor (also at hobbyking) sucks terribly, it induces BAD eddy currents in the motor, making it get really hot. And you'll need a controller that sends the right speed-control signal. Good luck!