Modulation - Renesas RA6T2 Application Note

RA6T2
Vector control for permanent magnetic synchronous motor with encoder - AB incremental type encoder

3.1.3 Modulation

The target software of this application note uses pulse width modulation (hereinafter called PWM) to
generate the input voltage to the motor. And the PWM waveform is generated by the triangular wave
comparison method.
(1) Triangular wave comparison method
The triangular wave comparison method is used to output the voltage command value. By this method, the
pulse width of the output voltage can be determined by comparing the carrier waveform (triangular wave)
and voltage command value waveform. The voltage command value of the pseudo sinusoidal wave can be
output by turning the switch on or off when the voltage command value is larger or smaller than the carrier
wave respectively.
U
Figure 3-1 Conceptual Diagram of the Triangular Wave Comparison Method
R01AN6208EJ0101 Rev.1.01
Oct 18, 2022
V
Modulation wave: command voltage
Carrier wave (triangular wave): PWM timer count
W
ωt
U phase switching
waveform
ωt
V phase switching
waveform
ωt
Voltage between U – V lines
(U phase waveform)
(V phase waveform)
ωt
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