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Disadvantages Of Bldc Motors

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Brushless Direct Current (BLDC) motors are one of the motor types rapidly gaining popularity. BLDC motors are used in industries such as Appliances, Automotive, Aerospace, Consumer, Medical, Industrial Automation Equipment and Instrumentation. As the name implies, BLDC motors do not use brushes for commutation; instead, they are electronically commutated. BLDC motors have many advantages over brushed DC motors and induction motors. A few of these are:

• Better speed versus torque characteristics
• High dynamic response
• High efficiency
• Long operating life
• Noiseless operation
• Higher speed ranges

In addition, the ratio of torque delivered to the size of the motor is higher, making it useful in …show more content…
Most BLDC motors have three stator windings connected in star fashion. Each of these winding is constructed with numerous coils interconnected to form a winding. one or more coils are placed in the slots and they are interconnected to form a winding. Each of these winding is distributed over the stator periphery to form an even numbers of poles. There are two types of stator windings variants: trapezoidal and sinusoidal …show more content…
BLDC motors can be commutated by monitoring the back EMF signals instead of the Hall sensors. The relationship between the Hall sensors and back EMF, with respect to the phase voltage, is shown in Figure 7. As we have seen in earlier sections, every commutation sequence has one of the windings energized positive, the second negative and the third left open. As shown in Figure 7, the Hall sensor signal changes the state when the voltage polarity of back EMF crosses from a positive to negative or from negative to positive. In ideal cases, this happens on zero-crossing of back EMF, but practically, there will be a delay due to the winding characteristics. This delay should be compensated by the microcontroller. Figure 10 shows a block diagram for sensorless control of a BLDC

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