Aerospace applications utilize 2,930 Hz to 10 kHz at voltages ranging from 4 V RMS to 10 V RMS.
Synchro resolver theory generator#
Resolvers designed for terrestrial use tend to be driven at 50–60 Hz ( utility frequency), while those for marine or aviation use tend to operate at 400 Hz (the frequency of the on-board generator driven by the engines). This allows for geared reduction of assemblies being rotated and improved accuracy from the resolver system.īecause the power supplied to the resolvers produces no actual work, the voltages used are usually low (<24 VAC) for all resolvers. The resolver feedback signals are usually monitored for multiple revolutions by another device. In practice, the resolver is usually directly mounted to an electric motor.
This device can be used in any application in which the exact rotation of an object relative to another object is needed, such as in a rotary antenna platform or a robot. Multipole resolvers may also be used for monitoring multipole electrical motors. Two-pole resolvers can usually reach angular accuracy up to about ±5′, whereas a multipole resolver can provide better accuracy, up to 10′′ for 16-pole resolvers, to even 1′′ for 128-pole resolvers. Some types of resolvers include both types, with the 2-pole windings used for absolute position and the multipole windings for accurate position. They have 2 p poles ( p pole pairs), and thus can deliver p cycles in one rotation of the rotor: the electrical angle is p times the mechanical angle. Other types of resolver are multipole resolvers. These devices can deliver the absolute angle position. They convert the sine and cosine signal to a binary signal (10 to 16 bits wide) that can more easily be used by the controller.īasic resolvers are two-pole resolvers, meaning that the angular information is the mechanical angle of the stator.
Synchro resolver theory driver#
When used with electronic driver amplifiers and feedback windings tightly coupled to the input windings, their accuracy is enhanced, and they can be cascaded ("resolver chains") to compute functions with several terms, perhaps of several angles, such as gun (position) orders corrected for ship's roll and pitch.įor the position evaluation, resolver-to-digital converters are commonly used. Resolvers with four output leads are general sine/cosine computational devices. Resolvers with four-lead rotors can rotate and coordinates, with the shaft position giving the desired rotation angle. Shaft angle is the polar angle, and excitation voltage is the magnitude. Resolvers can perform very accurate analog conversion from polar to rectangular coordinates. This device may also appear in non-brushless type, i.e., only consisting in two lamination stacks, rotor and stator.
Synchro resolver theory full#
Upon one full revolution, the feedback signals repeat their waveforms. The relative magnitudes of the two-phase voltages are measured and used to determine the angle of the rotor relative to the stator. The two two-phase windings, fixed at right (90°) angles to each other on the stator, produce a sine and cosine feedback current. This current then flows through the other winding on the rotor, in turn inducing current in its secondary windings, the two-phase windings back on the stator. As these windings are arranged on the axis of the resolver, the same current is induced no matter what its position. The primary winding of the transformer, fixed to the stator, is excited by a sinusoidal electric current, which by electromagnetic induction induces current in the rotor. The rotor houses a coil, which is the secondary winding of the turning transformer, and a separate primary winding in a lamination, exciting the two two-phase windings on the stator. They are configured at 90 degrees from each other. The two other windings are on the bottom, wound on a lamination. This transformer induces current in the rotor without wires or brushes to provide a direct electrical connection. The exciter winding is located on the top it is a coil of a turning (rotary) transformer. The stator portion of the resolver houses three windings: an exciter winding and two two-phase windings (usually labeled "x" and "y") (case of a brushless resolver). On the inside, the configuration of the wire windings makes it different. On the outside, this type of resolver may look like a small electrical motor having a stator and rotor. The most common type of resolver is the brushless transmitter resolver (other types are described at the end).