
Under
1-100
Specifications in this manual are tentative and subject to change
Rev. G
Timer Functions For Three-phase Motor Control
MITSUBISHI MICROCOMPUTERS
M30222 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
finishes outputting one-shot pulses, "0" already shifted in the three-phase shift register goes effective,
and the U phase waveform changes to the "L" level. When the Timer B2 counter’s content becomes
0000
16
, the Timer A4 counter starts counting the value written to Timer A4-1 (0347
16
, 0346
16
), and
starts outputting one-shot pulses. When Timer A4 finishes outputting one-shot pulses, the three-
phase shift register’s content is shifted one position, but if the three-phase output shift register’s con-
tent changes from “0” to “1” as a result of the shift, the output level changes from “L” to “H” without
waiting for the timer for setting dead time to finish outputting one-shot pulses. A U phase waveform is
generated by these workings repeatedly. With the exception that the three-phase output shift register
on the U phase side is used, the workings in generating a U phase waveform, which has the opposite
phase of the U phase waveform, are the same as in generating a U phase waveform. In this way, a
waveform can be picked up from the applicable terminal in a manner in which the "L" level of the U
phase waveform doesn’t lap over that of the U phase waveform, which has the opposite phase of the
U phase waveform. The width of the “L” level too can be adjusted by varying the values of Timer B2,
Timer A4, and Timer A4-1. In dealing with the V and W phases, and V and W phases, the latter are of
opposite phase of the former, have the corresponding timers work similarly to dealing with the U and
U phases to generate an intended waveform.
Fig. 1.74. Timing chart operation (1)
Timer A4 output
Trigger signal for
Timer Ai start
(Timer B2 overflow
signal)
Timer B2
U phase
Dead time
A carrier wave of triangular waveform
Carrier wave
Signal wave
Timer B2 interrupt occurs
Rewriting Timer A4 and Timer A4-1.
Possible to set the number of overflows to generate an
interrupt by use of the interrupt occurrences frequency
set circuit
U phase
output signal
m
n
n
m
p
o
Note: Set to Triangular wave modulation mode and to Three-phase mode 1.
Control signal for
Timer A4 reload
m
The Three-phase
shift register
shifts in
synchronization
with the falling
edge of the A4
output.
U phase
U phase
output signal