AN1857 Freescale Semiconductor / Motorola, AN1857 Datasheet - Page 37

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

AN1857
MOTOROLA
The volts-per-hertz profile is defined by these parameters:
The ramp profile fits the specific motor and can be easily changed to
accommodate different ones.
This software function, RAMP.C, provides voltage calculation according
to a V/Hz ramp. The input of this software function is the generated
inverter frequency V_out.
Parameters required by the PWM generation process are the output of
this software function:
The process of sine wave generation provides 3-phase sine waves,
each shifted by 120 degrees relative to each other. The sine waves can
be pure sine waves or they may include a third harmonic component.
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Freescale Semiconductor, Inc.
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VOLTAGE
VOLTAGE
Base point — Defined by base frequency (usually 50 Hz or 60 Hz)
Boost — Defined by boost voltage and boost frequency
V_out and is used to roll through the wave table to generate the
output inverter frequency
Amplitude of the generated inverter voltage
Table increment Table_inc that corresponds to the frequency
BOOST
PHASE
100%
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FREQUENCY
BOOST
Figure 23. Volts-per-Hertz Ramp
FREQUENCY
BASE POINT
BASE
FREQUENCY (rpm)
Application Note
Software
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