Now, if the electronic controller is able to supply phase

Ph1 in order to maintain

δ=90° the equation abo-

ve (2) can be simplified as

previous considerations it is clear the reason why a BLDC motor needs always position sensors to know

exactly rotor position. Fig. 1 shows a transversal section of a typical three phase brushless motor.

Figure 1 . Three-phase brushless motor

Figure 2. Motor Data Sheet

H1

H2

H3

Linked Voltage for Counterclockwise direction

In the diagram, three position sensors (Hall sensors) are placed around the rotor in order to detect the

shaft position. Fig. 2 reports motor data sheet supplied by the motor builder.

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AN1113 - APPLICATION NOTE

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