In a brushless DC (BLDC) motor, permanent magnets are mounted to the rotor, and the stator has windings that are energized by external current to produce electromagnetic poles. Brushless motors use electrical commutation to determine the switching sequence of the stator coils, and BLDC motors can be driven with either trapezoidal or sinusoidal commutation. Trapezoidal commutation is […]
DC Motors
FAQ: What are ways to avoid torque ripple in DC motors?
Torque ripple—variations in torque production during shaft revolution—is an undesirable effect that occurs in permanent magnet motors, preventing smooth motor rotation. Torque ripple is generally defined as non-linear torque production of an energized motor. Cogging torque—a phenomenon similar to torque ripple—is torque produced by the attraction between the permanent magnets of the rotor and the […]
FAQ: What are Hall effect sensors and what is their role in DC motors?
DC motors can be either brushed type, which are mechanically commutated, or brushless, which are commutated electrically. In brushless DC (BLDC) motors, Hall effect sensors are used in place of a mechanical commutator and brushes. Hall effect sensors are solid-state, magnetic field sensors. They work on the principle that when a conductor with current flowing through […]
FAQ: Can DC motors run at lower than nominal voltage?
In a DC motor, the relationships between voltage and speed and between current and torque are straightforward. When the load (torque) on the motor is constant, speed is proportional to the supply voltage. And when the supply voltage is constant, speed is inversely proportional to the load (torque) on the motor. Specifications for DC motors include […]
FAQ: Why are DC motor armature cores made of laminations?
DC motors are constructed with two major parts: the rotor and the stator. The rotor has a ring-shaped iron core with slots that hold coils, or windings. Following Farady’s law, when the core is rotated in a magnetic field, a voltage, or EMF, is induced in the coils. This induced EMF causes current to flow, […]
FAQ: What is the Swinburne test for DC motors?
The Swinburne test is an indirect method for determining the efficiency of DC motors. It works by finding the no-load losses experimentally and then estimating additional losses from the rated motor data. From this information, the efficiency can be determined at any applied load. First, the no-load current and shunt field current are obtained directly […]
FAQ: What are rotational losses in DC motors?
DC motors, like all machines, experience some losses when converting electrical power to mechanical power. (Note that in generators, mechanical power is converted to electrical power, but the losses experienced are the same.) While there are several ways in which manufacturers and experts group losses, one common method is to divide them into five categories: mechanical, […]
PITTMAN introduces DC022C series brush dc motor
PITTMAN a business unit of AMETEK Precision Motion Control, now offers the latest addition to its line of brush-commutated DC motors — the DC022C Series … a 22-mm diameter unit offered in three lengths with continuous output torques of 0.0056 to 0.141 Nm. More after the jump. The DC022C Series is offered with eight standard windings with special windings […]
Torquemaster family of brush DC motors from Torque Systems
Torque Systems, a division of SL-MTI, has developed a high performance family of three new size-15 permanent magnet dc motors. They are used in a wide range of applications that includes semiconductor processing equipment, robots, UAVs and medical devices. The longer stack size 15 DC motor (model MS1525-A) reaches a rated torque value of 10 […]
FAQ: How can brush wear in DC motors be minimized?
Brushed DC motors provide high speed and torque, are simple to operate, and are generally inexpensive. But one characteristic that is often viewed as a drawback is brush wear, which can necessitate frequent maintenance and downtime, and in extreme cases, can result in motor failure. Brushed DC motors are commutated mechanically, through the use of a commutator […]