TB6634FNG Datasheet, PDF (18/29 Pages) Toshiba Semiconductor – 3-Phase Full-Wave Sine-Wave PWM Brushless Motor Controller

TB6634FNG
The position signals from Hall sensors are modulated, and the modulated signals are then compared against a
triangular waveform to generate a sine-wave PWM.
The counter measures the period from given rising (or falling) edges of three hall signals to their next falling (or
rising) edges (60 electrical degrees). This period is then used as 60° phase data for the next modulation.
A total of 32 ticks comprise 60 electrical degrees; the length of a tick equals 1/32nds the time period of the
immediately preceding 60° phase.
HU
⑥①
③
HV
*HU, HV, HW: Hall signal
⑤
②
HW
⑥’ ①’ ②’ ③’
S_U
S_V
Sw
In the above diagram, the modulated waveforms have an interval (①’) equal to 1/32nds of the interval between a
rising edge of HU to a falling edge of HW (①) of the previous cycle.
Likewise, the modulated waveforms have an interval (②’) equal to 1/32nds of the interval between a falling edge
of HW to a rising edge of HV (②) of the previous cycle.
If 32 ticks finish modulated before ①’ or ②’ ends, next 32 ticks modulate with the same time width until the next
falling edge.
*t
32
31
30
6
5
4
3
2
1
S_V
①’
32 ticks
* t = t① × 1/32
Moreover, the phase match with the modulated waveform is done at every zero crossing of the positional
detection signal.
The modulated waveform is reset on each falling or rising edge of the positional detection signal, which
occurs every 60° electrical degrees.
Therefore, the modulated waveform becomes discontinuous at each reset while the position of the hall
signal misaligns or the motor is accelerating or decelerating.
Note: In the above diagram, HU is shown as square waveforms for the sake of simplicity.
18
2015-4-3