Comparison Of Advantages And Disadvantages Between Brushed And Brushless Motor Schemes

A brushed DC motor produces a maximum torque at rest, which decreases linearly with increasing speed. Brushless motors can overcome some of the limitations of brushed motors; They include higher efficiency and lower sensitivity to mechanical wear. These benefits come at the cost of potentially less robust, more complex, and more expensive control electronics.
Typical brushless motors have permanent magnets that rotate around a fixed armature, eliminating the problem of connecting current to a moving armature. An electronic controller replaces the brush/commutator component of the brushless DC motor, which constantly switches the phase of the windings to keep the motor running. The controller performs a similar timing power distribution by using a solid-state circuit instead of a brush/commutator system.
Brushless DC motors offer several advantages over brushless DC motors, including high torque-to-weight ratio, greater torque per watt (improved efficiency), higher reliability, lower noise, longer service life (brushless and commutator corrosion), elimination of ionizing sparks from commutators, and overall reduction of electromagnetic interference (EMI). Since there are no windings on the rotor, they are not subject to centrifugal force, and since the windings are supported by the housing, they can be cooled by conduction and do not require airflow inside the motor to cool them. This in turn means that the interior of the motor can be completely enclosed and protected from dirt or other foreign substances.
Brushless motor commutation can be implemented in software using a microcontroller or microprocessor computer, in analog hardware, or in digital firmware using a field programmable gate array (FPGA). Reversing with electronics instead of brushes allows for greater flexibility and functionality not available with brushed DC motors, including speed limits, "micro-step" operation for slow and/or fine motor control, and holding torque at rest. The controller software can be customized to specific motors for use in the application, resulting in greater commutation efficiency.
The maximum power applied to a brushless motor is largely limited by heat, and too much heat will weaken the magnet and damage the insulation properties of the windings.
Brushless motors are more efficient than brushless motors when it comes to converting electricity into mechanical power. This improvement is largely due to the frequency of the switching current determined by the position sensor feedback. The additional benefit is due to the absence of brushes, which reduces mechanical energy loss due to friction. Efficiency gains are greatest in the no-load and low-load areas of the motor performance curve. Under high mechanical loads, the efficiency of brushless motors and high-quality brushed motors is comparable.
The environments and requirements for manufacturers to use brushless DC motors include maintenance-free operation, high speed, and spark hazards or potentially affecting the operation of electronically sensitive equipment.
The structure of a brushless motor may be similar to that of a stepper motor. Unlike stepper motors, brushless motors are typically used to produce continuous rotation. Stepper motors generally do not include shaft position sensors for internal feedback on rotor position. Instead, the stepper controller will rely on sensors to detect the position of the device being driven. They often stop when the rotor is in a defined angular position, while still producing torque. A well-designed brushless motor system can also be maintained at zero RPM and limited torque.