AN2515 Freescale Semiconductor / Motorola, AN2515 Datasheet - Page 4

• Manufacturer Part Number: AN2515
• Description: 3-Phase Sine Wave Generator - 3 outputs version TPU Function Set
• Manufacturer: Freescale Semiconductor / Motorola

AN2515/D
Detailed Function Description
3-Phase Sine Wave
Generator – 3
outputs version
(3Sin3)
4
NOTE:
3-Phase Sine Wave Generator – 3 outputs version TPU Function Set (3Sin3)
A CPU routine that configures the TPU can be generated automatically using
the MPC500_Quick_Start Graphical Configuration Tool.
The 3Sin3 TPU function generates a 3-channel, 3-phase PWM signal. Unlike
3Sin, the generated signals are not top-bottom pairs with dead-times but only
top-like signals without dead-time. In order to charge the bootstrap transistors,
the PWM signals start to run 1.6ms after their initialization (at 20MHz TCR1
clock). The function generates signals corresponding to an amplitude of 0 (50%
duty-cycle) until the first reloaded values are processed.
The CPU controls the PWM output by setting the TPU parameters. The Stator
Reference Voltage Vector Amplitude Ampl, the Stator Reference Voltage
Vector angle Theta (32-bit) and the angle increment dTheta (32-bit), can be
adjusted during run time. The PWM period T and the prescaler – the number of
PWM periods per reload of new values – are also read at each reload, so these
parameters can be changed during run time. Conversely, the minimum pulse
width (MPW) is not supposed to be changed during run time. The CPU notifies
the TPU that the new reload values are prepared by setting the LD_OK
parameter. The TPU notifies the CPU that the reload values have been read
and new values can be written by clearing the LD_OK parameter.
The TPU function rotates the Stator Reference Voltage Vector by dTheta angle
each period – so the TPU can drive the motor with constant amplitude and
constant speed independently of the CPU. The CPU can adjust the Ampl
parameter to change the Stator Reference Voltage Vector amplitude, and the
dTheta parameter to change the rotation speed. The CPU can also set the
absolute value of Stator Reference Voltage Vector angle Theta. To notify the
TPU that the Theta parameter should be loaded instead of using the buffered
value, the CPU must set LD_OK = $8001 instead of $0001.
The following equations describe how the 3-phase sine wave PWM signal high-
times ht
calculated:
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3Sin3_res channels are initialized after the initialization of the PWM
channels:
–
–
–
A
, ht
assign a priority to the PWM channels to enable their initialization
if a Synchronization Signal or a Resolver Reference Signal channel
is used, wait until the HSR bits are cleared to indicate that
initialization of the PWM channels has completed and
assign a priority to the 3Sin3_sync or 3Sin3_res channels to enable
their initialization
B
, ht
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C
and transition times t
low-high
and t
high-low
of each channel are
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