Inductive Rotary Joint

• US 20090276199A1
• Filed: 05/05/2009
• Published: 11/05/2009
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Schleifring Und Apparatebau Gmbh (Wegmann Unternehmens-Holding GmbH & Co. KG)
• Original Assignee: Schleifring Und Apparatebau Gmbh (Wegmann Unternehmens-Holding GmbH & Co. KG)
• Inventors: Bley, Michael, Lohr, Georg, Krumme, Nils, Weithmann, Herbert
• Granted Patent: US 8,129,865 B2
• Time in Patent Office: Days
• US Class Current: 703/7
• CPC Class Codes: A61B 6/03 Computed tomography [CT] echo-tomography A61B8/14
• CPC Class Codes: A61B 6/56 Details of data transmission or power supply, e.g. use of slip rings
• CPC Class Codes: H01F 2038/143 for signals
• CPC Class Codes: H01F 38/18 Rotary transformers
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02P 9/10 Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load

Abstract

An inductive rotary joint for non-contact transmission of electrical energy between a stationary part and a rotating part of the rotary joint comprises a power generator for generating an alternating voltage or an alternating current, which feeds a load by means of a rotatable power transmitter. An electrical parameter on the primary side of the power transmitter is determined with a measurement means, and from this, the condition of another electrical parameter at the load is approximated by means of a functional unit. Regulation of the power generator is effected with this approximated value.

Claims

1. An inductive rotary joint for non-contact transmission of electrical energy between a stationary part and a rotating part of the rotary joint, comprising:

a power generator for generating an alternating voltage or an alternating current;

an inductive power transmitter comprising a primary side and a secondary side, in which the primary side is fed by the power generator and the secondary side feeds a load;

a measurement means for determining at least one electrical parameter selected from a group comprising;

a voltage, a current, and a phase angle of electrical energy fed by the power generator into the primary side of the power transmitter; and

a functional unit for controlling the power generator with the aid of the at least one electrical parameter, so that at least one other electrical parameter on the load is maintained approximately constant, wherein the at least one other electrical parameter is selected from a group comprising a voltage, a current, and a phase angle of the electrical energy fed onto the load, and wherein the functional unit comprises a model for simulating a relationship between the at least one other electrical parameter on the load and the at least one electrical parameter on the primary side of the power transmitter.

2. The rotary joint according to claim 1, wherein the model is a characteristic function or a family of characteristic functions which can be also multi-dimensional in accordance with a number of input parameters supplied by the measurement means, and output parameters sent to a control amplifier.

3. The rotary joint according to claim 2, wherein the characteristic function is produced on a basis of results of a circuit simulation in which the characteristic function describes a dependence of voltage on the load as a function of a switching frequency of the power generator and current into the primary side of the power transmitter.

4. The rotary joint according to claim 1, wherein the model simulates a response of the rotary joint under an assumption of a simplified equivalent circuit diagram.

5. The rotary joint according to claim 1, wherein the model is based on at least one transmission characteristic function obtained by measurement.

6. The rotary joint according to claim 1, wherein the model approximates at least one range of the transmission function as being a linear function.

7. The rotary joint according to claim 1, wherein the model comprises a simulation of the transmission function with analog passive constructional components.

8. The rotary joint according to claim 1, wherein the model approximates at least one range of the transmission function by means of a resistance- and diode-network.

9. The rotary joint according to claim 1, wherein the model approximates at least one range of the transmission function by means of a logarithmic amplifier.

10. The rotary joint according to claim 1, wherein the model also takes into account at least one mechanical parameter selected from a group comprising:

a distance between the rotating part and the stationary part, a size of an air-gap between the primary side of the power transmitter and the secondary side of the power transmitter, and an angular position between the rotating part and the stationary part.

11. The rotary joint according to claim 1, wherein the functional unit comprises a digital computer having a digital signal processor.

12. The rotary joint according to claim 1, wherein the model is stored as a mathematical model in the functional unit, and the transmission function is computed at a time of operation.

13. The rotary joint according to claim 1, wherein the model is stored as a table in a memory.

14. The rotary joint according to claim 1, wherein the functional unit comprises means for adaptive measurement or adaptive learning of model parameters.

15. A computer tomograph including an inductive rotary joint, comprising:

a power generator for generating an alternating voltage or an alternating current;

an inductive power transmitter comprising a primary side and a secondary side, in which the primary side is fed by the power generator and the secondary side feeds a load;

a measurement means for determining at least one electrical parameter selected from a group comprising;

a voltage, a current, and a phase angle of electrical energy fed by the power generator into the primary side of the power transmitter; and

a functional unit for controlling the power generator with the aid of the at least one electrical parameter, so that at least one other electrical parameter on the load is maintained approximately constant, wherein the at least one other electrical parameter is selected from a group comprising a voltage, a current, and a phase angle of the electrical energy fed onto the load, and wherein the functional unit comprises a model for simulating a relationship between the at least one other electrical parameter on the load and the at least one electrical parameter on the primary side of the power transmitter.