RSBJEUM0001-0101 Rev. 1.01
10
Figure 3.1.2 Three-phase IGBT inverter circuit
In the 120 degree trapezoidal communication mode, three phase IGBT circuit turn-on sequence
is UpWn→WnVp→VpUn→UnWp→WpVn→VnUp, two IGBT are conducted every 60 electrical
degrees. Accordingly, PWM wave have 6 output pattern switching. It is shown as the figure 3.1.1
and figure 3.1.2
Output pattern is switched when motor rotor angles 60 electrical degree every time.
Zero-crossings of the induced voltages is at the mid of each output pattern (30 electrical degree).
In this program, the function of output pattern switching is carried out by PFCR register of
M16C62A. It can control each bit in the PFCi (i=0 to 5) to enable each one of three-phase PWM
output pins. When setting the PFCi (i=0 to 5) to “0”, three-phase PWM output pin functions act as
I/O port and can output “H” level state and “L” level state.
In order to outputting PWM wave when motor rotor angles 360 electrical degrees, PFCR register
should be set based the following table.
Table 3.1.1 PFCR correspond to different output pattern
The three-phase PWM output pins have three states, PWM wave, “H” and “L”, the output states
depend on PFCR register, Pi register and PDi register. The output states table is shown on Table
3.1.2.
Wn
Wp
Vn
Vp
Un
Up
X
X
PFC5
PFC4
PFC3
PFC2
PFC1
PFC0
Pattern 0
0
0
0
0
0
0
0
1
Pattern 1
0
0
1
0
0
0
0
0
Pattern 2
0
0
0
0
0
1
0
0
Pattern 3
0
0
0
0
0
0
1
0
Pattern 4
0
0
0
1
0
0
0
0
Pattern 5
0
0
0
0
1
0
0
0
Up
Un
VCC
GND
Vp
Wp
Vn
Wn
