DRV10983-Q1 Datasheet, PDF (41/72 Pages) Texas Instruments – Automotive, Three-Phase, Sensorless BLDC Motor Driver

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DRV10983-Q1
SLVSD14 – JUNE 2017
8.4.12.3 Motor Electrical-Period Readback
The motor-operation electrical period is automatically updated in register MotorPeriod while the motor is spinning.
The electrical period is measured as the time between calculated BEMF zero crossings for phase U. The
electrical period of the motor is denoted as t_{ELE_PERIOD} (µs) and is calculated as shown in Equation 10.
t_{ELE_PERIOD} (µs) = {MotorPeriod} × 10
(10)
As an example consider the following:
MotorPeriod = 0x01FF;
t_{ELE_PERIOD} = 512 (0x01FF) × 10 = 5120 µs
The motor electrical period and motor speed satisfies the condition of Equation 11.
t_{ELE_PERIOD} (s) × Velocity (Hz) = 1
(11)
8.4.12.4 Motor Velocity Constant Read Back
For any given motor, the integrated value of BEMF during half of an electronic cycle is a constant, Ktc (see
Lock2: Abnormal Kt ).
The integration of the motor BEMF is processed periodically (updated every electrical cycle) while the motor is
spinning. The result is stored in register MotorKt.
The relationship is shown in .
Ktc (V/Hz) = {MotorKt} / 2 / 1090
(12)
8.4.12.5 Motor Estimated Position by IPD
After inductive sense is executed, the rotor position is detected within 60 electrical degrees of resolution. The
position is stored in register IPDPosition.
The value stored in IPDPosition corresponds to one of the six motor positions plus the IPD advance angle as
shown in Table 8. For more information about IPD, see IPD.
Table 8. IPD Position Read Back
U
VU
VU
VU
V_U
VU
V
N
W
Rotor position (°)
0
Data1
0
IPD advance angle
30
Data2
22
Register data
W
W
W
60
120
180
43
85
128
60
90
120
44
63
85
(Data1 + Data2) mod (256)
S
W
W
240
300
171
213
8.4.12.6 Supply-Voltage Readback
The power supply is monitored periodically during motor operation. This information is available in register
SupplyVoltage. The power supply voltage is recorded as shown in Equation 13.
V_POWERSUPPLY (V) = Supply Voltage × 30 V / 256
(13)
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