AN1857 Freescale Semiconductor / Motorola, AN1857 Datasheet - Page 34

• Manufacturer Part Number: AN1857
• Description: A 3-Phase ac Induction Motor Control System Based on the MC68HC908MR32
• Manufacturer: Freescale Semiconductor / Motorola

Freescale Semiconductor, Inc.
Application Note
When the MR32 is reset, the software configures the various system I/O.
The forward/reverse switch, start/stop switch, and dc bus voltage are
checked, and the speed potentiometer’s value is input. A yellow LED
located on the control board is illuminated when the system is ready. The
identification of the connected boards (optoisolator and power boards) is
checked. The default operation mode is set to manual. The PC-Master
operation mode can be set by the PC-Master command. The PFC
algorithm is initialized. After the initialization is passed, the fault flag
(failure) is tested for any system faults. Anytime a fault is detected in the
system, a red LED located on the control board will illuminate. The
system name for dc bus voltage is Out_volt_new. The value input from
the speed pot is labeled Pot_voltage.
The input parameters of the process are evaluated and the speed
command V_command is calculated accordingly. Also, the dc bus
voltage, named dc_bus_volt, is measured. The general fault Gf_flag is
analyzed and the state of the drive is set. The drive state diagram is
shown in
Figure
21. The status LEDs are controlled according the
system state.
The calculated speed command V_command is a 2-byte variable with
the format (1 Hz = 0x0100). The upper byte represents the integer
portion and the lower byte represents the fractional portion of the value.
This format is kept through all the program for all the speed variables.
The system software calculates a new speed based on the requested
speed, according to the acceleration/deceleration ramp.
AN1857
34
MOTOROLA
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