Rotary transformer
A rotary transformer is a special type of transformer in which the primary side can mechanically rotate freely in relation to the secondary side. This is achieved through a rotationally symmetrical structure.
Rotary transformers are used to transport signals or energy wear-free from or to rotating parts. One example is magnetic data recording using helical track recording, as is the case with video recorders or digital data storage , where the rapidly rotating head drum carrying the magnetic heads contains a rotary transformer in order to bring the signals to and from the device without wear and friction.
Another example is space probes , where there are rotating parts.
Rotary transformers are alternatives to slip rings , but they can also transmit direct voltage, but slip rings are subject to greater wear and tear and therefore have a shorter service life . Another alternative is capacitive signal transmission.
construction
A rotary transformer consists of two halves: a fixed stator with the first winding (blue in the illustration opposite) and a rotor with the second winding (red) rotating on an axis. A round core which surrounds the windings and which is divided into two halves (stator and rotor) is used to guide the magnetic flux Φ between the two windings . Due to this subdivision and the resulting air gap between the stationary and rotating core halves, these transformers have a comparatively high magnetic leakage flux .
There are also constructions with a single core and a free-standing rotating winding. This has the advantage that the air gap lies outside the parts positioned with respect to one another and does not change in the event of bearing wear or irregularities. This also enables a stronger coupling.
In contrast to electric motors , which also have a stator and rotor, rotary transformers do not serve to generate or transmit mechanical forces as a result of the magnetic field.
Rotary transformers can be used both for the transmission of alternating voltage and for data or signal transmission. With the head drums in magnetic recording devices with helical track recording , several separate transmission paths are usually provided for this. Two to six parallel transmission paths leading to the individual reading heads on the outer edge of the head drum are common. The various windings, like the cores, are arranged in concentric circles around the axis.
- Head drum of a video recorder
Head drum with the windings in the rotor and concentrically arranged winding pairs
Stator of a head drum in a video recorder with the mirror-inverted fixed windings
literature
- Ulrich Schmidt: Professional video technology: analog and digital basics, film technology, television technology, HDTV, cameras, displays, video recorders, production and studio technology . 4th edition. Springer, 2005, ISBN 978-3-540-24206-2 .
Web links
Individual evidence
- ^ SH Marx, RW Bounds: A Kilowatt Rotary Power Transformer . IEEE Transactions on Aerospace and Electronic Systems, 1971, ISSN 0018-9251 , doi : 10.1109 / TAES.1971.310219 ( online ).
- ↑ http://www.google.com/patents/EP0374749A1?cl=de