RC08Brushless

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In 2008 RoboCup switched to brushless DC motors. While brushless motors are smaller and far more efficient than brushed motors the commutation normally performed inside a brushed DC motor will need to be done externally using some control circuitry. There are two main parts to our brushless motor controller solution; the controller which uses sensors on the motor to gate signals to one of three coils, and the half-bridge motor drivers which actually drive the coils.For the controller a special-purpose brushless motor driver IC was used. For information on the motors or motor control software please see their respective pages.

Motor Frequency Analysis

Tasks

  • [ ] Get the motor and begin playing with it
    • [X] Call Maxon and get a recommendation on motor drivers (They spec parts not sure which drivers they use)
    • [X] Figure out max current draw. (10A starting current)
    • [ ] Develope Model of Motor and get Frequency Response
    • [ ] Find and purchase Flat Flex Cable (FFC) connectors
    • [ ] Purchase large mosfets for testing
    • [ ] Purchase Surfboard for mounting DSC
    • [ ] Build test rig
  • [ ] Finalize on a DSC
  • [ ] Choose MOSFETS
  • [ ] Sample all the parts
  • [ ] Schematic Design
  • [ ] Build prototype
  • [ ] Prototype evaluation
  • [ ] Make necessary changes

Specifications

Motor Controller Chip

  • The motor is spec'd at 12V and is 30W
  • A decent transient response (dead-time + switching time)
  • 3-Channels in one package
  • Braking is not a requirement but would be nice
  • High Impedance OFF state
  • Fault protection (overvoltage, overcurrent, fast response)
  • Small package
  • Ability to operate in the >20kHz range
  • Gate drive capability (either can directly driver the gate or is open drain.)
  • Data sheet recommends a MOSFET
  • Matrix of Potential Drivers

MOSFET

Schematics

Parts

We are performing commutation on the FPGA with gate drivers.

Gate Driver

Microchip TC4428

  • 1.5 A
  • 6 mA quiescent
  • Noninverting low side
  • Inverting high side

FETS

Part No. Make Package ContIDS MaxIDS Rds MaxVGS Samples Data Sheet
NTMS4503N N-Channel ON Semi SO-8 14 A -- -- 28 V Y [1]
NTMS10P02 P-Channel ON Semi SO-8 10 A -- -- 20 V Y [2]

Motor Connector

Hirose FH12-11S-1SH 11 position 1 mm pitch

Commutation

CW (looking along the shaft toward the motor)

HS 1 HS 2 HS 3 Winding 1 Winding 2 Winding 3
1 0 1 Vcc Gnd n.c.
1 0 0 Vcc n.c. Gnd
1 1 0 n.c Vcc Gnd
0 1 0 Gnd Vcc n.c.
0 1 1 Gnd n.c. Vcc
0 0 1 n.c. Gnd Vcc

CCW (looking along the shaft toward the motor)

HS 1 HS 2 HS 3 Winding 1 Winding 2 Winding 3
1 0 1 Gnd Vcc n.c.
1 0 0 Gnd n.c. Vcc
1 1 0 n.c Gnd Vcc
0 1 0 Vcc Gnd n.c.
0 1 1 Vcc n.c. Gnd
0 0 1 n.c. Vcc Gnd

To find this data:

I duplicated the tables here because the text on the site is generated by Javascript, the frame URL contains a session ID, and the back button doesn't work.

Articles

Modeling a DC motor Brush-Less Motor Simulink

Links