ATAVRMC300 Atmel, ATAVRMC300 Datasheet - Page 3

• Manufacturer Part Number: ATAVRMC300
• Description: BOARD EVAL LV MOTOR CONTROL PWR
• Manufacturer: Atmel
• Series: AVR®r

Specifications of ATAVRMC300

• Main Purpose: Power Management, Motor Control
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: ATmega32M1
• Primary Attributes: 3-Ph BLDC, Brushed DC, Stepper Motor Driver Board, 40V, 6A
• Secondary Attributes: Requires ATAVRMC301, ATAVRMC303, or ATAVRMC310
• Processor To Be Evaluated: ATmega32M1
• Data Bus Width: 8 bit
• Interface Type: RS-232, USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.3
2.4
8138A–AVR–04/08
Hall Sensor
Phase Commutations
The coils are stationary while the magnet is rotating. The rotor of the BLDC motor is lighter than
the rotor of a conventional universal DC motor where the coils are placed on the rotor.
For the estimation of the rotor position, the motor is equipped with three hall sensors. These hall
sensors are placed every 120°. With these sensors, 6 different commutations are possible.
Phase commutation depends on hall sensor values.
Power supply to the coils changes when hall sensor values change. With right synchronized
commutations, the torque remains nearly constant and high.
Figure 3. Hall Sensors signals for CW rotation
To simplify the explanation of how to operate a three phase BLDC motor, a typical BLDC motor
with only three coils is considered. As previously shown, phases commutation depends on the
hall sensor values. When motor coils are correctly supplied, a magnetic field is created and the
rotor moves. The most elementary commutation driving method used for BLDC motors is an on-
off scheme: a coil is either conducting or not conducting. Only two windings are supplied at the
same time and the third winding is floating. Connecting the coils to the power and neutral bus
induces the current flow. This is referred to as trapezoidal commutation or block commutation.
To command brushless DC motors, a power stage made of 3 half bridges is used.
below shows a 3 half bridge schematic.
Coil_W
Coil_U
Coil_V
Hall_1
Hall_2
Hall_3
t
t
t
t
t
t
AVR194
Figure 4
3