Rotor

In a position encoder or resolver system, the rotor is the moving part that rotates relative to the stator. It typically contains patterned elements (like magnetic poles, optical patterns, or conductive windings) that interact with the stationary sensor elements to produce electrical signals corresponding to its angular position, speed, and direction of rotation. The rotor is mounted on the shaft whose position is being measured, and its design is critical for the encoder's performance. Common materials include electrical steel (silicon steel), permanent magnets (e.g., neodymium), and aluminum alloy. The outer diameter of the rotor is a key specification, measured in millimeters, and must be compatible with the stator and overall package size. For industrial applications, the rotor must be selected based on the specific encoder type, operating environment, and required accuracy. Verification of model-specific dimensions and material properties is essential, and the legal manufacturer or supplier should be consulted for exact specifications. The rotor's interaction with the stator determines the signal quality and resolution. In magnetic encoders, the rotor's magnetic poles create a varying magnetic field; in optical encoders, the rotor's pattern interrupts or reflects light; in resolvers, the rotor's windings induce voltages. The resulting signals are decoded to provide precise angular position feedback. Proper installation and alignment are crucial to avoid errors. Maintenance signals include unusual noise, vibration, or signal degradation, which may indicate wear or damage. The rotor's operational boundaries are defined by its mechanical strength, temperature limits, and speed ratings, which must be confirmed for each application.

The rotor rotates with the shaft whose position is being measured. Its patterned surface (e.g., magnetic poles, optical code disk, or resolver windings) interacts with the fixed sensor elements in the stator. This interaction—through magnetic field variation, light interruption/reflection, or inductive coupling—generates sinusoidal or digital output signals. The phase, frequency, or code of these signals is then decoded by the encoder/resolver electronics to determine the precise angular position.