Electromagnetic Compatibility And Optimization Design Of High-intensity Focused Ultrsound Power Source

High Intensity Focused Ultrasound (HIFU) therapy is a newnon-invasive treatment technology of concern. With the advantage ofnon-invasive, targeted, and non-ionizing radiation, etc., it is listed as oneof the important issues of science and technology frontier. We are of worldleading level in the development of HIFU therapy equipment and clinicalapplication. HIFU therapy equipment electromagnetic compatibility isimportant safety performance indicators which related to the safety of thepatients, the international general use the mandatory standard to provideHIFU equipment’s electromagnetic compatibility, our YY0505standard isalso gradually implemented in2014. Thus, improving the security of EMCHIFU therapy system is of great significance to the promotion ofdevelopment of HIFU treatment technology.This paper focuses on the issues of HIFU power sourceelectromagnetic compatibility, especially research the following three keyissues, the circuit design and optimization of HIFU power source, the power source load impedance changes affect work performance analysisand HIFU power source electromagnetic interference shielding andconduction testing, radiation testing. First, we design and develop a HIFUpower source based on the Class E power amplifier, and optimize thecircuit, Ensure that the power source to work in optimal working condition.In addition, contraposeing the HIFU power source performance undervarying load condition, this paper made a mathematical analysis andestablished a certain range of the class E power amplifier circuit load ofthe output size, scope and power switch output stress efficiency. Finally,HIFU power sources for electromagnetic compatibility design,electromagnetic compatibility testing by the actual prototype design wasverified. The main results obtained in this article are at following:（1） Designed a HIFU source based on class E power amplifier, theoperating frequency of the power source is1.05MHz, the output poweris10W.The circuit simulation were optimized by the Saber software, itoptimized the output waveform and improved the output efficiency of thecircuit.（2） Contraposed the HIFU power source’s transducer impedanceinstability characteristic when in the actual work, theoretical analyzed theimpact of load impedance variation on Class E ultrasound power amplifieroperating characteristics, established the mathematical model of loadimpedance and output power, efficiency, and analyzed the change stress of switching device under varying load condition. Verified the afford range ofClass E power amplifier load impedance by actual circuit.（3） To solve the electromagnetic interference problems of HIFUpower source, the high frequency current probe for measuring current ofthe power supply interference and the output current were designed in thispaper; and shielding box were designed to reduce radiated interference;optimized the circuit to reduce the interference from output harmonic, andtest the conducted emission and radiated interference for HIFU powersource in electromagnetic compatibility standard room.