The torque-pulse rate characteristics of a stepper motor is the graph plotted between the electromagnetic torque and the stepping rate. It gives the variation of electromagnetic torque as a function of stepping rate in pulses per second (pps). A stepper motor is usually described by two characteristic curves as shown ... Read More

The equivalent circuit parameters of a single-phase induction motor can be determined from the blocked rotor and no-load tests. Except, the capacitor-run motor, the blocked rotor and no-load tests are performed with auxiliary winding kept open.Blocked Rotor Test on Single-phase Induction MotorIn the blocked rotor test, the rotor of the ... Read More

Why doesn't a Single-Phase Induction Motor Self-Start?A single-phase induction motor consists of a squirrel cage rotor and a stator carrying a single-phase winding. But, a single-phase induction motor is not self-starting like a 3-phase induction motor since it requires some starting means.When a single-phase supply is fed to the stator ... Read More

The working principle of a single-stack variable reluctance (VR) stepper motor is based on the property of the flux lines to occupy the low reluctance path. Therefore, in a variable reluctance stepper motor, the stator and rotor get aligned such that the magnetic reluctance is minimum.Construction of Single-Stack Variable Reluctance ... Read More

Schrage motor is an inverted 3-phase induction motor with primary winding on the rotor and the secondary winding on the stator. The schematic diagram of a 2-pole Schrage motor is shown in the figure.In a Schrage motor, a 3-phase supply is fed to the rotor circuit. The resultant air-gap flux ... Read More

A hybrid stepper motor combines the features of the variable reluctance and the permanent magnet stepper motors. In the hybrid stepper motor, an axial permanent magnet is provided in the middle of the rotor. The permanent magnet is magnetised axially to produce a pair of poles marked N and S ... Read More

A permanent magnet (PM) stepper motor has salient pole stator. The stator has concentrated windings placed over the stator poles. It has cylindrical rotor and consists of permanent magnet poles made up of high retentivity steel. The construction of a 4/2-pole (i.e., 4-poles on the stator and 2-poles on the ... Read More

A multi-stack variable reluctance stepper motor having m-stacks can be considered to be made of m identical single-stack variable reluctance stepper motors with their rotors mounted on a single shaft.In the multi-stack variable reluctance stepper motor, the stators and the rotors have the same number of poles or teeth and ... Read More

The motors that can be used with a single-phase AC source as well as a DC source of supply voltages are called as universal motors. A universal motor is a commutator type motor. If the polarity of the line terminals of a DC series motor is reversed, the motor will ... Read More

Basics of ServomotorsServomotors are the electromechanical energy conversion devices. In other words, a Servomotors is a rotary actuator or linear actuator which is used for precise control of linear or angular position, velocity and acceleration.A servomotor consists of an electric motor coupled with a sensor for position feedback. Servomotors are ... Read More