Archives: Glossaries

Variable Reluctance Motor

Variable Reluctance Motors have no permanent magnet, thus the rotor spins freely as there is no detent torque. The step angle of a VR motor is in the medium range, generally 5 to 15 degrees. This type of motor is also used in non-industrial applications where a high degree of torque is not required.

Unipolar Motors

These motors are composed of two windings, each with a center tap. The center taps are either brought outside the motor as two separate wires or connected to each other internally and brought outside the motor as one wire, resulting in 5 or 6 wires.

Torque

A measurement of the amount of force acting on an object that causes the object to rotate.

Stator

The stationary part of the motor. Specifically, it is the iron core with the wire winding in it that is pressed into the shell of the frame. The winding pattern determines the voltage constant of the motor.

Sourcing Current

Refers to the current flowing out of the output of the chip. This means that a device connected between the chip output and the negative supply will be switched on when the output is high.

Slew

The position of a move profile where the motor is operating at a constant velocity.

Sinking Current

Refers to the current flowing into the output of the chip. This means that a device connected between the positive supply and the chip output will be switched on when the output is low.

Shaft

The portion of the rotor that lies on the spin axis of the rotor and is the rotor interface to the stator portion of the magnetic bearings and motor generators.

Serial Peripheral Interface Bus (SPI)

Is a synchronous serial data link that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select lines.