lb11891v Sanyo Semiconductor Corporation, lb11891v Datasheet - Page 7

• Manufacturer Part Number: lb11891v
• Description: Three-phase Brushless Motor Driver For Streaming Tape Drives
• Manufacturer: Sanyo Semiconductor Corporation

Overlap Creation and Calculations
Overlap Creation
For the voltages generated in the control block, if the midpoint is taken as the reference, one side will be
2 O.L.
Therefore, the waveform crossover will be
Since that waveform is clamped at
the overlap will be:
Overlap Calculation
(1) High side overlap
(2) Low side overlap
Calculated midpoint
The calculated midpoint is
Since A =
Overlap =
Since C = VN – V and D = VN – VXL, the low side overlap can be calculated as follows.
Overlap =
Absolute voltage
(
— VS – VX
1
2
VS-VXH
— = ————————————————
— = —————————————
A
B
C
D
– VN and B = VS – VXH – VN, the high side overlap can be calculated as follows.
VXL
VN
VS
V
V
0
—
A
B
((VS – VXH + VXL)/2) – VXL
VS – VXH – ((VS – VXH + VXL)/2)
((VS – VXH + VXL)/2) – V
)
.
100 = O.L. 100 [%]
V – ((VS – VXH + VXL)/2)
VN = ———————— + VXL = ————————
(
— VS – VX
1
2
(VS – VXH – VXL)
Electrical
angle
O.L.
2
180
.
)
A
(
referenced to the midpoint,
— VS – VX
1
2
C
LB11891V
100 = ————————————
D
)
(VS – VXH) + VXL – 2V
B
100 = ————————————
from the midpoint.
(VS – VXH) – VXL
VS – VXH – VXL
2V – ((VS – VXH) – VXL)
(VS – VXH – VXL)
2
High side residual voltage VXH
Low side residual voltage VXL
O.L
VS
VS
Low side clamp potential
High side clamp potential
100 [%]
Time
2
– VXH
(
VS
2
100 [%]
– VXH)
.
VS-VX
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