| Permanent-Magnet Brushed DC Motor |
A permanent-magnet stator creates the stationary magnetic field, while a wound armature produces torque through a mechanical commutator and carbon or metallic brushes. |
Approximately 1,000–10,000 rpm, depending on voltage, winding, load, and motor size. |
Pulse-width modulation (PWM), adjustable DC voltage, or closed-loop feedback. PWM is commonly used because it maintains useful torque at reduced average speed. |
Medium to high; approximately 2–5 times rated running torque can be available for short periods, subject to thermal and mechanical limits. |
Typically 60–85% for small and medium motors. |
Simple drive electronics, low initial cost, good low-speed torque, and easy reversal by changing polarity. |
Brush and commutator wear, electrical arcing, audible noise, electromagnetic interference, and limited service life in demanding environments. |
Small pumps, fans, actuators, office equipment, battery-powered tools, toys, and light automation. |
Check brush life, duty cycle, stall protection, allowable PWM frequency, noise limits, operating temperature, and replacement accessibility. |
| Separately Excited DC Motor |
The armature and field winding are supplied by electrically separate sources, allowing independent control of armature voltage and field current. |
Approximately 500–3,000 rpm in standard industrial configurations; higher speeds are possible with suitable mechanical design. |
Armature-voltage control provides constant-torque operation below base speed. Field weakening provides approximately constant-power operation above base speed. |
High and highly controllable; starting torque is set by armature current and field strength. |
Typically 75–93%, depending on rating, speed, and field losses. |
Wide speed range, precise torque control, and flexible operation in four-quadrant drive systems. |
Requires a separate field supply, larger control system, brushes, commutator maintenance, and careful field-loss protection. |
Test stands, rolling equipment, elevators, hoists, large conveyors, and legacy variable-speed industrial drives. |
Confirm field-supply requirements, minimum field current, drive regeneration capability, overspeed protection, and maintenance resources. |
| Shunt-Wound Brushed DC Motor |
The field winding is connected in parallel with the armature, so field current remains relatively stable as the load changes. |
Approximately 500–3,000 rpm, with comparatively small speed variation from no-load to rated-load operation. |
Armature-voltage control for below-base-speed adjustment; field weakening can extend speed above the base value. |
Medium; generally lower than a series-wound motor but suitable for loads that do not require extreme starting torque. |
Typically 75–92% for industrial-sized motors. |
Good speed regulation, stable operation, and suitable performance for continuous-duty loads. |
Brush maintenance, lower starting torque than series motors, and possible overspeed if the field circuit is interrupted. |
Machine tools, fans, centrifugal pumps, paper-processing equipment, and constant-speed conveyors. |
Provide field-loss protection, verify continuous-duty cooling, and match the motor's speed regulation to the load profile. |
| Series-Wound Brushed DC Motor |
The field winding is connected in series with the armature, so the same current flows through both circuits and magnetic flux increases with load current until saturation. |
Approximately 500–5,000 rpm under load; speed can rise dangerously at no load. |
Armature voltage, PWM, or a series resistor for basic control. A controlled drive is preferred for safe speed regulation. |
Very high; often suitable for heavy starting loads and rapid acceleration. |
Typically 75–90% near rated load. |
Exceptional starting torque, compact torque-producing design, and good short-term overload capability. |
Unsafe at no load, poor speed regulation, brush wear, commutator arcing, and limited suitability for precision speed control. |
Traction equipment, cranes, hoists, lifts, winches, and older starter or propulsion systems. |
Use mechanical or electronic overspeed protection, ensure the motor cannot operate unloaded, and verify the duty cycle carefully. |
| Compound-Wound Brushed DC Motor |
Combines shunt and series field windings. The shunt field improves speed regulation while the series field increases starting torque. |
Approximately 500–3,000 rpm, depending on the compound connection and design. |
Armature-voltage control, PWM, and field weakening. The control strategy must account for both field circuits. |
High; normally higher than a shunt motor and lower or more controlled than a pure series motor. |
Typically 75–92%. |
Balanced torque and speed regulation for variable-load machinery. |
More complex winding and control requirements, brush maintenance, and possible instability if incorrectly connected. |
Presses, elevators, conveyors, compressors, shears, and heavy machine tools. |
Specify cumulative or differential compounding, starting-load profile, overload duration, and field-connection requirements. |
| Brushless DC Motor (BLDC) |
Permanent magnets are mounted on the rotor, while electronically switched stator windings create a rotating magnetic field. Electronic commutation replaces brushes and a mechanical commutator. |
Approximately 1,000–30,000 rpm; specialized designs can operate outside this range. |
Six-step trapezoidal commutation, PWM duty-cycle control, Hall-sensor feedback, sensorless back-EMF control, or field-oriented control (FOC). |
High, but it depends on controller current limits, rotor position feedback, and thermal capacity. |
Typically 80–95%; high-quality systems can exceed 90% across a broad operating region. |
High efficiency, long service life, low maintenance, quiet operation, high power density, and accurate electronic control. |
Requires a compatible electronic controller, position sensing or a sensorless algorithm, electromagnetic-compatibility design, and protection against overheating or demagnetization. |
Electric mobility, robotics, HVAC blowers, drones, pumps, medical equipment, appliances, and automated production systems. |
Match motor phase count, controller voltage, continuous and peak current, Hall-sensor sequence, feedback type, IP rating, and regenerative-braking capability. |
| Coreless or Ironless Brushed DC Motor |
The rotor uses a lightweight self-supporting winding without a conventional iron core. A permanent-magnet stator provides the magnetic field, and brushes provide mechanical commutation. |
Approximately 2,000–20,000 rpm, depending on diameter, winding, and load. |
PWM, adjustable voltage, current limiting, and closed-loop speed control. Acceleration and deceleration should be limited to protect the lightweight rotor. |
Low to medium continuous torque, with very fast acceleration because of low rotor inertia. |
Typically 60–85%; short-term dynamic response is often more important than peak efficiency. |
Very low inertia, rapid response, low cogging torque, low electrical inductance, and smooth motion. |
Lower continuous thermal capacity, brush wear, possible high current ripple, and sensitivity to excessive acceleration or stall conditions. |
Camera mechanisms, compact medical devices, precision instruments, miniature pumps, and fast positioning systems. |
Check permissible peak current, stall time, brush rating, rotor balance, acceleration limit, and required motion smoothness. |
| Geared DC Motor |
A brushed or brushless DC motor drives a gearbox, usually using spur, planetary, worm, or helical gears to reduce speed and increase output torque. |
Motor speed may be 1,000–30,000 rpm; gearbox output is commonly approximately 5–500 rpm. |
Motor PWM, voltage control, current control, and encoder-based closed-loop control. Output speed is determined by motor speed divided by the gear ratio, subject to slip and load. |
High output torque after reduction; gearbox efficiency and allowable peak torque must be included in calculations. |
Approximately 50–90% for the complete motor-and-gearbox assembly, depending strongly on ratio, gear type, lubrication, and load. |
High output torque, compact packaging, lower output speed, and easy integration with position or speed feedback. |
Gear noise, backlash, wear, limited shock-load capability, reduced efficiency, and possible thermal buildup at low output speed. |
Electric actuators, automated doors, conveyor drives, valve actuators, AGVs, robotics, and positioning mechanisms. |
Calculate continuous and peak output torque, gear ratio, backlash, radial and axial loads, gearbox service life, lubrication, and brake requirements. |
| Tubular Linear DC Motor |
Converts electrical energy directly into linear force using permanent magnets and electronically switched or mechanically commutated windings, eliminating a rotary-to-linear transmission. |
Linear speed is commonly approximately 0.1–5 m/s; force and speed depend on stroke, cooling, and drive design. |
PWM current control, force control, position feedback, and closed-loop servo control. Current is the primary variable for force production. |
High peak force is available from zero speed, subject to continuous-force and thermal limits. |
Typically 70–95% for the motor and drive system, depending on operating point. |
Low mechanical backlash, direct linear motion, rapid response, and reduced transmission maintenance. |
Requires accurate guidance, position feedback, thermal management, and protection from side loads and contamination. |
Pick-and-place equipment, semiconductor machinery, packaging systems, precision stages, and automated inspection equipment. |
Specify continuous and peak force, stroke, travel speed, duty cycle, guidance accuracy, encoder resolution, and cooling method. |
