PM Stepper Motor

A permanent magnet stepper motor uses a magnetized cylindrical rotor and multi-tooth stator to produce discrete rotational steps. The stator contains windings on diametrically opposite poles connected in series to form two phases. When drive phases are energized in sequence, the rotor aligns with the changing magnetic field. These motors are commonly two-phase designs; step angles vary by model and may include 3.75°, 7.5°, 15°, or 18° depending on construction.

The magnetized rotor provides detent torque that can hold position when unpowered, within specified limits. During operation, a driver receives step/direction signals and energizes stator phases in sequence, generating a rotating magnetic field that the rotor follows. With microstepping, phase currents are modulated to create smaller increments between full step positions. When combined with an encoder and closed-loop driver, the system can adjust current to track commanded position.

When selecting a PM stepper motor, verify torque requirements against speed-torque curves, confirm electrical compatibility with the driver, and check mechanical fit including frame size, mounting pattern, and shaft dimensions. These motors are used in instrumentation, laboratory equipment, printers, vending machinery, compact pumps, and positioning fixtures. Application suitability depends on load conditions, duty cycle, and required motion profile.