
ML66517 Family User’s Manual
Chapter 10
3-Phase PWM Function
10 – 38
10.4.2 Operation Examples in Each Mode
10.4.2.1 Mode 1 Operation Example 1
Figure 10-30 shows an example of PWMU output and PWMUB output (U-phase) for the 3-phase AC motor
control waveform described in the mode 1 register setting example 1 of section 10.3.2.3. PWMV output,
PWMVB output (V-phase), PWMW output, and PWMWB output (W-phase) operate in the same manner.
PW3C begins counting when the PW3CRUN bit is set to “1”. With PW3C
≤ PW3UR, the PWMU pin (positive
phase) outputs a low-level and the PWMUB (reverse phase) outputs a high-level. If PW3C
≥ PW3UR, the output
of the size comparator changes from a low-level to a high-level, the dead time timer is activated, and PWMU
(positive phase) changes from a low-level to a high-level. When the dead time timer halts, the PWMUB (reverse
phase) pin output changes from a high-level to a low-level.
PW3C continues upward counting. If PW3C matches the contents of PW3CYR, an interrupt is generated and
PW3C begins counting downward. If necessary, the next duty value is set in PW3UBFR and the next PWM
cycle is set in PW3CYBFR within the interrupt processing routine.
PW3C continues downward counting. If PW3C
≤ PW3UR, the output of the size comparator changes from a
high-level to a low-level, the dead time timer is activated, and the PWMUB (reverse phase) pin output changes
from a low-level to a high-level. When the dead time timer halts, the PWMU (positive phase) pin output changes
from a high-level to a low-level.
PW3C continues downward counting. If underflow of PW3C occurs, an interrupt is generated, the contents of
PW3CYBFR are loaded into PW3CYR, the contents of PW3UBFR are loaded into PW3UR, a count value of
0000H is repeated twice and then upward counting begins. If necessary, the next duty value is set in PW3UBFR
and the next PWM cycle is set in PW3CYBFR within the interrupt processing routine.
The 3-phase AC motor driving waveform is generated in this manner.