AN1905 ST Microelectronics, Inc., AN1905 Datasheet - Page 54

• Manufacturer Part Number: AN1905
• Description: St7mc Three-phase BLDC Motor Control Software Library
• Manufacturer: ST Microelectronics, Inc.

ST7MC THREE-PHASE BLDC MOTOR CONTROL SOFTWARE LIBRARY
7.1.2 Connecting the sensor outputs to the board
Two configurations are commonly used: sensor 60 / sensor 120 degrees.
The easiest and most time-efficient solution is to connect the motor cables into the demokit by
trying all the connection style combinations.
First you need to check which sensor distribution is used by connecting the sensor outputs to
a scope and running the motor smoothly (by hand, for example). The consecutive events (in
the time domain) have to be monitored (with a scope/multimeter): 3 successive rising/falling
edges means a sensor 60 configuration, while an alternate rising/falling edge means a sensor
120 configuration.
Now that the sensor distribution is known, you have to randomly connect the sensor outputs to
the demokit (select the right sensor configuration in the GUI). As there are 3 phases (let’s say
P1,P2 and P3), that simply means we have 6 possibilities of connection: P1P2P3, P1P3P2,
P2P1P3, P2P3P1, P3P1P2 and P3P2P1.
For each connection, you may try to start the motor (with the GUI for example) and find out
which 1 of the 6 cable connections is able to run the motor properly. If none of them is able to
do so (wrong motor direction), then 2 sensor cables have to be swapped and the same proce-
dure repeated.
Warning:
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Make sure that the duty cycle is not set too high as the winding currents
can increase very quickly, especially if the motor is stalled.