AN1915D Freescale Semiconductor / Motorola, AN1915D Datasheet - Page 15

• Manufacturer Part Number: AN1915D
• Description: 3-Phase BLDC Motor Control with Quadrature Encoder using DSP56F80x
• Manufacturer: Freescale Semiconductor / Motorola

MOTOROLA
4.2 Application Description
A standard system concept is chosen for the drive (see
following hardware boards:
The DSP runs the main control algorithm. According to the user interface and feedback signals, it
generates 3-phase PWM output signals for the BLDC inverter.
The control process is as follows:
The state of the user interface is periodically scanned, while the speed of the motor is measured on
each rising edge from the Quadrature Encoder (only one phase is used for speed measurement).
According to the state of the control signals (Start/Stop switch, speed up/down buttons) the speed
command is calculated. The comparison between the actual speed command and the measured speed
generates a speed error. The speed error is brought to the speed PI controller that generates a new
corrected duty cycle. The duty cycle value together with commutation algorithm creates the PWM
output signals for the BLDC power stage.
The Quadrature Encoder signals are converted to six interrupts per electrical revolution. This interrupt
provides the commutation algorithm.
In the case of under-voltage, the PWM outputs are disabled and the fault state is displayed.
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Power Supply 12V DC, 4Amps
EVM Motor Board
BLDC Motor IB23810 with Quadrature Encoder
Evaluation Board DSP56F803, DSP56F805 or DSP56F807
DSP56F805EVM
PC Master
START
DOWN
STOP
UP
3-Phase BLDC Motor Control with Quadrature Encoder
Freescale Semiconductor, Inc.
DSP56F805
For More Information On This Product,
R
S
2
3
2
G
P
O
I
Controller
Figure 4-1. System Concept
PI
±
Go to: www.freescale.com
Req
Commutation
Handler
Calculation
Speed
P
W
M
M
E
R
D
E
C
O
D
E
R
T
I
Quadrature Encoder
PWM1-6
Figure
4-1). The system incorporates the
Motor Board
12V DC
BLDC
motor
EVM
System Concept
15