Modeling Of A Bldc Motor Essay

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Modeling of a BLDC motor can be developed in the similar manner as a three phase synchronous machine. Since its rotor is mounted with a permanent magnet, some dynamic characteristics are different. Flux linkage from the rotor is dependent upon the magnet. Therefore, saturation of magnetic flux linkage is typical for this kind of motors. As any typical three phase motors, one structure of the BLDC motor is fed by a three phase voltage source as shown in Figure 2.10. The source is not necessary to be sinusoidal. Square wave or other wave- shape can be applied as long as the peak voltage is not exceeded the maximum voltage limit of the motor. Similarly, the model of the armature winding for the BLDC motor is expressed as follows. Figure 2.10: Equivalent circuit of the BLDC motor 2.4.1 Voltage Equation (2.1) (2.2) (2.3) Assuming constant self and mutual inductance, the voltage equation becomes (2.4) The electromagnetic torque is given as T_e=(e_a i_a+e_b i_b+e_c i_c)/ω (2.5) Where: : are the phase voltages : are the phase stator currents R: is the stator resistance of each phase L: is the stator self inductance per phase M: is the mutual inductance. The induced back emf depends on the rotor position and can be given as follows: (2.6)
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