1908

Item 1908

DESIGN ~ Electrotor-SloMo ~ Control - Electric - Electronic - Outrunner Project

Also see;

MAKE ~ Electrotor-SloMo ~ Control - Electric - Power - Outrunner Project

BUY ~ Electric - Controller - Kelly

Build 2:

Redundancy Considerations:

Have 2 controllers and each controller drive half of the coils in each motor. This will assure that both motors are receiving partial power if one circuit should fail.

This may also contribute to better electrical synchronization.

B/ [Mod. 1?] Control by Back-EMF ~ Sensorless?:

Microchip: For information on Microchip see; DESIGN: Electrotor-SloMo - Control (flight & electric) - Control Circuit - Three-phase - Overview ~ Microchip. The following is from; Microchip, AN857, Brushless DC Motor Control Made Easy

"There are several disadvantages to sensorless control:

The motor must be moving at a minimum rate to generate sufficient back EMF to be sensed

Abrupt changes to the motor load can cause the BEMF drive loop to go out of lock

The BEMF voltage can be measured only when the motor speed is within a limited range of the ideal commutation rate for the applied voltage • Commutation at rates faster than the ideal rate will result in a discontinuous motor response"

Kelly: For information on Microchip see; DESIGN: Electrotor-SloMo - Control (flight & electric) - Control Circuit - Three-phase - Overview ~ Kelly. Note: All Kelly sensorless controllers are shown as 'Beta Test Version'

Cooling:

The two controllers could be located over the pilot's head to be cooled and deflect some of the downwash away from the pilot.

Miscellaneous:

For comparison of MOSFET and IGBT see Microchip, AN898, Determining MOSFET Driver Needs for Motor Drive Applications
Microchip, AN857, Brushless DC Motor Control Made Easy ~ Source code Have hard copy

Electrical Synchronization of two rotors: I would think that is should be possible to read and compare the outputs from the 3 Hall sensors on each rotor. This information could be sent to a timing comparator circuit where the requested power of one motor is reduced and that of the other motor is increased. Additional assured synchronization will probably be required but it may be only back up for the electrical one.

Other Parts:

Opto-isolators:

Associated Pages:

Last Revised: August 2, 2011