Motorola M68HC08 Manual page 47

6.1.2 Sensor Handler
6.1.3 Acceleration Ramp
DRM046 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.
calculated accordingly. Also the DC bus voltage, ucVoltageDCB, is
measured.
The application utilizes 3-phase Hall position sensor for control
algorithm. It is used for both commutation vector generation and for the
actual speed calculation.
For the calculation of the commutation vector, all three Hall sensor
inputs are evaluated. A three-bit commutation pattern,
ucSensorVector, is created. It is later used for selection of proper
commutation pattern in process Commutation & PWM Generation.
The speed measurement utilizes the IC function of the timer. It reads the
time between consequential rising edges of the selected phase of Hall
sensor output, and calculates the actual motor speed,
uiOmegaActual. Also, a software filter of the speed measurement may
be incorporated into the process for better noise immunity. In this case
the actual motor speed is calculated as an average value of several
measurements.
The process calculates the new speed command, uiOmegaReqRamp,
based on the required speed, ucOmegaReq, according to the
acceleration ramp.
During deceleration the motor can work as a generator. In the generator
state the DC-Bus capacitor is charged and its voltage can easily exceed
its maximal voltage. Therefore the DC-Bus voltage is measured and
compared with the limit. In the case of deceleration over-voltage, the
deceleration is interrupted and the motor runs with constant speed in
order to discharge the capacitor. Then deceleration can continue.
Software Design
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Software Design
Data Flow
Designer Reference Manual
47