Three-phase Motor Control Timer Functions
137
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Start trigger signal
for timer A4*
Timer B2
U phase
Carrier wave
Signal wave
U phase
output signal *
m
n
n
p
p
m
U phase
U phase
U phase
INV14 = 0
(“L” active)
Timer A4
one-shot pulse*
INV14 = 1
(“H” active)
Dead time
Dead time
Transfer to three-phase
output shift register
Rewriting IDB0, IDB1 registers
* Internal signals. See the block diagram of the three-phase motor control timer function.
An example for changing PWM outputs is shown below.
(1)When INV11=1(three-phase mode 1)
· INV01=0, ICTB2=2
16
(timer B2 interrupt is generated at every 2’th
occurrence of a timer B2 underflow), or INV01=1, INV00=1,
ICTB2=1
16
(timer B2 interrupt is generated at even-numbered
occurrences of a timer B2 underflow).
· Initial timer value: TA41=m, TA4=m. The TA4 and TA41 registers
are modified every time a timer B2 interrupt occurs. First time,
TA41= n, TA4 = n. Second time, TA41 = p, TA4 = p.
· Initial values of IDB0 and IDB1 registers: DU0 = 1, DUB0 = 0,
DU1 = 0, DUB1 = 1.The register values are changed to DU0 = 1,
DUB0 = 0, DU1= 1 and DUB1 = 0 the third time a timer B2
interrupt occurs.
The value written to the TA4 register and TA41 register are inverted at odd-numbered timer A outputs.
(2)When INV11=0(three-phase mode 0)
· INV01=0, ICTB2=1
16
(timer B2 interrupt is generated at every
occurrence of a timer B2 underflow)
· Initial timer value: TA4 = m. The TA4 register is modified each time
a timer B2 interrupt occurs. First time, TA4 = m. Second time, TA4 = n.
Third time, TA4 = n. Fourth time, TA4 = p. Fifth time, TA4 = p.
· Initial values of IDB0 and IDB1 registers: DU0=1, DUB0=0, DU1=0,
DUB1=1.The register values are changed to DU0 = 1, DUB0 = 0, DU1=
1 and DUB1 = 0 the sixth time a timer B2 interrupt occurs.
TB2S bit of the
TABSR register
INV13
(INV11=1(three-phase
mode 1))
Shown here is a typical waveform for the case where INVC0 = 00XX11XX
2
(X = set as suitable for the system) and INVC1 = 010XXXX0
2
.
U phase
output signal *
Figure 1.16.8. Triangular Wave Modulation Operation
The three-phase motor control timer function is enabled by setting the INV02 bit of INVC0 register to “1”.
When this function is on, timer B2 is used to control the carrier wave, and timers A4, A1 and A2 are used
to control three-phase PWM outputs (U, U, V, V, W and W). The dead time is controlled by a dedicated
dead time timer. Figure 1.16.8 shows the example of triangular modulation waveform and Figure 1.16.9
shows the example of sawtooth modulation waveform.