DRV10983-Q1 Datasheet, PDF (17/72 Pages) Texas Instruments – Automotive, Three-Phase, Sensorless BLDC Motor Driver

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DRV10983-Q1
SLVSD14 – JUNE 2017
8.4 Device Functional Modes
This section includes the logic required to be able to reliably start and drive the motor. It describes the processes
used in the logic core and provides the information needed to configure the parameters effectively to work over a
wide range of applications.
8.4.1 Motor Parameters
See the DRV10983-Q1 Tuning Guide for the motor parameter measurement.
The motor resistance and motor velocity constants are two important parameters used to characterize a BLDC
motor. The DRV10983-Q1 device requires these parameters to be configured in the register. The motor
resistance is programmed by writing the values for Rm[6:0] (combination of RMShift[2:0] and RMValue[3:0]) in
the Config1 register. The motor velocity constant is programmed by writing the values for Kt[6:0] (combination of
KTShift[2:0] and KTValue[3:0]) in the Config2 register.
8.4.1.1 Motor Resistance
For a wye-connected motor, the motor phase resistance refers to the resistance from the phase output to the
center tap, R_{PH_CT} (denoted as R_{PH_CT} in Figure 10).
Phase U
R_{PH_CT}
R_{PH_CT}
Center
Tap
R_{PH_CT}
Phase V
Phase W
Figure 10. Wye-Connected Motor Resistance
For a delta-connected motor, the motor phase resistance refers to the equivalent phase to center tap in the wye
configuration. In Figure 11, it is denoted as R_Y. R_{PH_CT} = R_Y.
For both the delta-connected motor and the wye-connected motor, the easy way to get the equivalent R_{PH_CT} is
to measure the resistance between two phase terminals (R_{PH_PH}), and then divide this value by two, R_{PH_CT} = ½
R_{PH_PH}.
Phase U
R_Y
R_û
R_û
R_Y
Center
R_Y
Tap
Phase V
R_û
Phase W
Figure 11. Delta-Connected Motor and the Equivalent Wye Connections
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