Efficiency-based compensations and the mechanical load dependencies of rotary transformer for rotary ultrasonic machining applications

A new rotary ultrasonic machining (RUM) spindle is proposed. It adopts contactless rotary transformer replacing the well-established slip ring technology to supply power for the transducer. Owing to the large leakage inductances, the capacitive piezoelectric transducer and the variable mechanical load, the circuit compensation is crucial for efficient and reliable power transfer. In this study, the mathematical models are presented to identify the power transfer efficiency and capability of the rotary transformer used in RUM. A general optimisation method of compensation for maximum transfer efficiency is proposed. The mechanical load dependencies of the transfer efficiency, transfer capability and power factor are researched and discussed. The efficiency has been found to be dependent of the secondary compensation elements. The series-series (SS) topology is applicable to a wide range of mechanical load variations, followed by parallel-series (PS) topology. For a varying load in RUM, the contactless energy transfer is possible to achieve high efficiency, high power factor and appropriate output power that adapts to load variations.

[1]  J. W. Kolar,et al.  Analysis of rotary transformer concepts for high-speed applications , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[2]  M. Komaraiah,et al.  Rotary ultrasonic machining— a new cutting process and its performance , 1991 .

[3]  Grant Covic,et al.  Power transfer capability and bifurcation phenomena of loosely coupled inductive power transfer systems , 2004, IEEE Transactions on Industrial Electronics.

[4]  A.P. Hu,et al.  Power Loss Analysis of a TET System for High Power Implantable Devices , 2007, 2007 2nd IEEE Conference on Industrial Electronics and Applications.

[5]  Hans-Christoph Skudelny,et al.  A new approach to power supplies for robots , 1991 .

[6]  Marc Perrottet,et al.  Transmission électromagnétique rotative d"énergie et d"information sans contact , 2000 .

[7]  Atsuo Kawamura,et al.  Wireless transmission of power and information through one high-frequency resonant AC link inverter for robot manipulator applications , 1995 .

[8]  John T. Boys,et al.  Stability and control of inductively coupled power transfer systems , 2000 .

[9]  Konstantinos D. Papastergiou,et al.  An Airborne Radar Power Supply With Contactless Transfer of Energy—Part I: Rotating Transformer , 2007, IEEE Transactions on Industrial Electronics.

[10]  Chih-Jung Chen,et al.  A Study of Loosely Coupled Coils for Wireless Power Transfer , 2010, IEEE Transactions on Circuits and Systems II: Express Briefs.

[11]  F. Pellitteri,et al.  Wireless battery chargers for portable applications: design and test of a high-efficiency power receiver , 2013 .

[13]  Wilson Eberle,et al.  Overview of wireless power transfer technologies for electric vehicle battery charging , 2014 .

[14]  Johann W. Kolar,et al.  Optimization of rotary transformer for high-speed applications , 2013, 2013 IEEE 14th Workshop on Control and Modeling for Power Electronics (COMPEL).

[15]  Nelson Sadowski,et al.  Analysis and Test Results of a Brushless Doubly Fed Induction Machine With Rotary Transformer , 2012, IEEE Transactions on Industrial Electronics.

[16]  Grant A. Covic,et al.  Design of loosely coupled inductive power transfer systems , 2000, PowerCon 2000. 2000 International Conference on Power System Technology. Proceedings (Cat. No.00EX409).

[17]  Hu Gong,et al.  Kinematic view of tool life in rotary ultrasonic side milling of hard and brittle materials , 2010 .

[18]  N. Frohleke,et al.  Inverter topologies for ultrasonic piezoelectric transducers with high mechanical Q-factor , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[19]  Aiguo Patrick Hu,et al.  A novel detached magnetic coupling structure for contactless power transfer , 2011, IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society.

[20]  Grant A. Covic,et al.  Load models and their application in the design of loosely coupled inductive power transfer systems , 2000, PowerCon 2000. 2000 International Conference on Power System Technology. Proceedings (Cat. No.00EX409).

[21]  L. Encica,et al.  Comparison of winding topologies in a pot core rotating transformer , 2010, 2010 12th International Conference on Optimization of Electrical and Electronic Equipment.