AN1915D Freescale Semiconductor / Motorola, AN1915D Datasheet - Page 23

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

MOTOROLA
5.2.3 Drive State Machine
6.
6.1 Scaling of Quantities
The drive can be in any of the states shown in
among the drive states. The user is able to recognize the current state, by a blinking green LED diode.
In case of the init and stop state, the green LED diode blinks with a frequency of 2 Hz. In the fault
state, the green LED diode blinks with a frequency of 8 Hz. During the running state the green LED
diode is continuously lit.
The BLDC motor control application uses a fractional representation for all real quantities except time.
The N-bit signed fractional format is represented using 1.[N-1] format (1 sign bit, N-1 fractional bits).
Signed fractional numbers (SF) lie in the following range:
For words and long-word signed fractions, the most negative number that can be represented is -1.0,
whose internal representation is $8000 and $80000000, respectively. The most positive word is $7FFF
or 1.0 - 2
The following equation shows the relationship between real and fractional representations:
where:
Fractional Value is a fractional representation of the real value [Frac16]
Real Value is the real value of the quantity [V, A, RPM, etc.]
Real Quantity Range is the maximal range of the quantity, defined in the application [V, A, RPM, etc.]
Implementation Notes
-15
, and the most positive long-word is $7FFFFFFF or 1.0 - 2
Stopped
3-Phase BLDC Motor Control with Quadrature Encoder
State
Figure 5-4. Drive State Machine Transitions
Freescale Semiconductor, Inc.
Fractional Value
For More Information On This Product,
SwitchState=RUN
–
1.0
SwitchState=STOP
SwitchState=RUN
Go to: www.freescale.com
SwitchState=STOP
SF +1.0 -2
=
------------------------------------------------- -
Real Quantity Range
State
Reset
Init
Real Value
–
u_dc_bus<MIN_DC_BUS_VOLTAGE
Figure
N 1
–
Running
5-4, which shows the transition conditions
State
u_dc_bus>=MIN_DC_BUS_VOLTAGE
-31
.
State
Fault
Implementation Notes
(EQ 6-1.)
(EQ 6-2.)
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