2018 Volume 15 Issue 20 Pages 20180833
An inductive power supply with concentric coreless transformer is proposed for the ultrasonic transducer on machine tools. The concentric coreless transformer is designed not to increase mounting weight onto the spindle and transfer power to the ultrasonic transducer without contact losses. A switching power supply composed of a series-parallel resonant compensation circuit and a full-bridge inverter is also designed to convert the power from stationary side to the rotary ultrasonic transducer (UST) through the coreless concentric transformer. A primary-side controller based on fed back primary-side current is also proposed for output voltage control. Therefore, there are only the secondary winding and the parallel compensation capacitor required to be mounted on to the spindle. From the experimental results, it can be seen that the proposed power supply can provide a stable AC power with 25 kHz/70 V to the ultrasonic transducer. The efficiency of the proposed power supply is up to 90% and the efficiency difference between stationary and rotary operations is only about 2%.