POWER SUPPLY FOR RADIO FREQUENCY HEATING APPARATUS

摘要

Power Supply for Radio Frequency Heating Apparatus An RF generator power supply comprises a first switched mode power supply (SMPS) connected in series to a second SMPS bya DC bus. A capacitor is arranged between the outputs of the first SMPS and inputs of the second SMPS to act as a smoothing capacitor for the first SMPS and to supply pulse energy to the second SMPS. The second SMPS has an output connected toan input of a step-up transformer and an output of the step-up transformer is connected to an input of a rectifier connectable to the RF generator. An input ofthe first SMPS is connectable to aprime power supply tomaintain a high power factor withlow harmonic content while setting anoperating voltage and peak current levelfor the RF generator. The second SMPSis arranged to feed thestep-up transformer and is arranged to operatewith a variable duty cycle and/or variable frequency to provideaverage power controlofthe RF generator. The second SMPS is rapidly switched off on detection of a power surge throughthe RF generator.