Title :
A modified class G amplifier for active magnetic bearings
Author :
Maddaleno, Franco ; Carabelli, Stefano ; Muzzarelli, Marco
Author_Institution :
Dept. of Electron., Politecnico di Torino, Italy
Abstract :
To improve the overall efficiency of a transconductance amplifier loaded by the high inductance and low resistance typical of the magnetic bearing coils, a modified class G amplifier has been developed. A third transistor has been connected from ground to output, in order to obtain high efficiency coil discharge. A simple theoretical characterization has been used to provide some diagrams to optimize the power efficiency as a function of a nonconstant load such as that due to a rotor unbalance. Experimentalal results are reported showing a good agreement with the developed theory
Keywords :
load (electric); machine bearings; magnetic devices; power amplifiers; power semiconductor switches; power transistors; active magnetic bearings; coil discharge; inductive load; magnetic bearing coils; modified class G amplifier; nonconstant load; power efficiency optimisation; rotor unbalance; theoretical characterization; transconductance amplifier; Actuators; Coils; Force control; Frequency; High power amplifiers; Inductance; Magnetic levitation; Power amplifiers; Transconductance; Voltage;
Conference_Titel :
Applied Power Electronics Conference and Exposition, 1997. APEC '97 Conference Proceedings 1997., Twelfth Annual
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-3704-2
DOI :
10.1109/APEC.1997.581510
