A new tracking method with FPGA chip for ultrasonic welding system
A new feedback control method of using field-programmable gate array (FPGA) chip for ultrasound welding system is appeared in this article. This feedback control circuits of ultrasound welding system consists of microprocessor control unit, signal generator, power amplifier, the feedback of voltage detector and current detector, etc. The experimental results exhibited this feedback control method can effectively and automatically catch frequency and rack a proper frequency for the ultrasound welding system.
Full-bridged MOSFET DC-to-RF inverter for high frequency ultrasonic transducer at 3 MHz
Described is a full-bridged MOSFET DC-to-RF inverter operating at a frequency of 3 MHz for driving a high frequency ultrasonic transducer for cleaning material surfaces. The full-bridged MOSFET DC-to-RF inverter generates an RF power of 60 W with a power conversion efficiency of 79 to 87% at 3 MHz when an ultrasonic transducer with a very low impedance in the order of 1 to 5 ohms is connected to the inverter. The ultrasonic transducer was satisfactorily operated when the ultrasonic transducer was driven from the full-bridged MOSFET DC-to-RF inverter.
DC-to-RF MOSFET power inverter with output power of 1 kW at 2.5 MHz
Described is a DC-to-RF MOSFET power inverter of full-bridged voltage-fed type consisting of four MOSFET arrays, each array consisting of six MOSFETs to enhance the output power to 1 kW at a frequency of 2.5 MHz. The total DC-to-RF power conversion efficiency was over 60% in the supplied DC voltage range of 80 to 180 V, at the output powers ranging from 250 to more than 1000 W. When the square-wave output voltage was fed to the resistive load whose characteristic impedance was 50 Omega when the load was used as an RF heater.<<ETX>>