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.
Fullbridged MOS-FET DC-to-RF power inverter for use with high-frequency high-power ultrasonic transducer
A full-bridge MOSFET DC-to-RF power inverter consisting of four branches, each branch consisting of three MOSFETs connected in parallel to enhance the power handling capability, was built for driving a high frequency, high power ultrasonic transducer with an output power of 600 W operating at 1 MHz. When the power inverter was connected to the ultrasonic transducer through an output transformer with a primary-to-secondary winding ratio of 2 to 1, the load impedance looking into the load from the inverter was 3.5 ohms at 1 MHz, and was high enough to drive the load with high power conversion efficiency, i.e., over 80%.<<ETX>>
Output power transformer load for DC-to-RF MOS-FET power inverter
Described are considerations for the optimum load for the DC-to-RF MOSFET power inverter of full-bridge type providing the output power transformer with minimum power loss, and also measurement of the impedance parameters of the output power transformers. The minimum reflectance of the output power transformer was -20 to -30 dB at a load of 13 ohms for the 2 to 1 winding ratio on the output power transformer at 1 to 10 MHz. The input impedance and network parameters were measured from a pair of tandem connected output power transformers. The input impedance was resistive at 50 ohms at 1 to 10 MHz. The transmittance was unity over the 1 to 10 MHz frequency range.<<ETX>>