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Meeting the Challenges Using BLDC Motor Topology Given the challenges discussed above, it becomes apparent that replacing or removing the brushes and commutator is essential. This is highlighted in the tri-phase BLDC motor topology (Figure 2). A BLDC motor can give us the same rotational motion without using brushes or a mechanical commutator. Instead, we generate the revolving magnetic field electronically. Using electronic circuitry, we can create two magnetic fields fighting each other to develop motor motion. The advantage: is no friction between the rotor and stator components, which increases reliability and energy efficiency. Tri-phase BLDC motors can reach efficiencies as high as 96 percent. This means our battery will only waste a 20th of its energy in the form of heat. As with all designs, employing BLDC motors has some challenges. Brushed DC motors solve the inherent problem of aligning magnetic fields to obtain the most efficient motion profile. They achieve this when the commutator sequence is designed and placed so that the revolving magnetic field is always in tune with the permanent magnets' field. However, because BLDC motors do not have a physical commutator, this action is done using commutation logic sequencing. To obtain the efficiencies we referenced, we must align both magnetic fields as perfectly as possible using a control circuit such as the one in Figure 3. This sophisticated circuitry extracts the rotor's position to align both magnetic fields electronically. In the case of a tri-phase BLDC motor, this block is most often made of a microcontroller and a tri-phase inverter power stage employing sensors, such as a Hall Sensor, to extract the rotor's position information. Adding this circuitry does take up some space and adds some cost. However, manufacturers are seeing the benefits of being untethered, and consumers demand these types of motor solutions. Thus, more power tools are being designed using tri-phase BLDC motor topology. Figure 2: Replacing or removing brushes and commutators is essential in the tri-phase BLDC motor topology (Source: Qorvo). The use of BLDC motor manufacturing is revving up... 20 Powering Up Your Design PAC5526 48V Charge Pump and Programmable Driver Motor Controller LEARN MORE >