TB6551F Datasheet, PDF (12/18 Pages) Toshiba Semiconductor – 3-Phase Full-Wave Sine-Wave PWM Brushless Motor Controller

TB6551F
The modulation waveform is generated using Hall signals. Then, the modulation waveform is compared
with the triangular wave and a sine-wave PWM signal is generated.
The time (electrical degrees: 60°) from the rising (or falling) edges of the three Hall signals to the next
falling (or rising) edges are counted. The counted time is used as the data for the next 60° phase of the
modulation waveform.
There are 32 items of data for the 60° phase of the modulation waveform. The time width of one data
item is 1/32 of the time width of the 60° phase of the previous modulation waveform. The modulation
waveform moves forward by the width.
HU
(6) (1)
(3)
HV
(5)
(2)
*HU, HV, HW: Hall signals
HW
(6)’ (1)’ (2)’ (3)’
S_U
S_V
Sw
In the above diagram, the modulation waveform (1)’ data moves forward by the 1/32 time width of the
time (1) from HU: ­ to HW: ¯. Similarly, data (2)’ moves forward by the 1/32 time width of the time (2) from
HW: ¯ to HV: ­.
If the next edge does not occur after the 32 data items end, the next 32 data items move forward by the
same time width until the next edge occurs.
*t
32
31
30
6
5
4
3
2
1
S_V
(1)’
* t = t(1) ´ 1/32
32 data items
The modulation wave is brought into phase with every zero-cross point of the Hall signal.
The modulation wave is reset in synchronization with the rising and falling edges of the Hall signal at
every 60° electrical degrees. Thus, when the Hall device is not placed at the correct position or when
accelerating/decelerating, the modulation waveform is not continuous at every reset.
12
2002-12-24