Dsp-based Ultrasonic Scalpel Power Control Circuit

With the development of science and technology, people are constantly seeking more kinds of tools and methods to treat disease. A kind of device called ultrasonic scalpel is used to smash and dissect the diseased tissue to achieve the purpose of surgical treatment, taking the place of ordinary ones. It has been widely used for the advantages of higher precision, less injury and faster recovery.However, the operating frequency of the ultrasonic scalpel will be changed with different emulsification tissues. If the ultrasonic scalpel cannot work in the resonant frequency, the ultrasonic energy will be wasted on the internal heat, resulting in treatment difficulties and damage of itself as the high temperature. The drive voltage is provided by the ultrasonic power, so the frequency of ultrasonic power needs to be adjusted timely to keep the vibration system working in the resonant state. Under this condition, the effect is the best:the power and the amplitude of vibration will reach the maximum value.In order to achieve this aim, a DSP-based power control system of ultrasonic scalpel is designed in this paper. Not only make timely adjustments to the change of resonant frequency, the system can also control the ultrasonic electric power. This paper is divided into six chapters. Chapterâ… is an introduction; Chapterâ…¡establishes the system design; Chapterâ…¢describes the hardware circuit design; Chapterâ…£introduces the DSP-based system software design and development; Chapter V includes experimental testing and data analysis; Chapterâ…¥is a summary and outlook. The main contents and the innovations are as follows:(1) A structure of the ultrasonic scalpel transducer is described with detailed analysis of the equivalent circuit of the transducer. Characteristics of the transducer's resonant frequency were studied through MATLAB simulation.(2) A system hardware circuit has been designed and produced based on DSP. In the circuit design process, an adjustable circuit of NC half-bridge PWM output with precise reference frequency is described, which is used to make sure the ultrasonic transducer can work on the resonant point precisely in power amplifier circuit by adjusting duty cycle of PWM.(3) A DSP-based control software has been designed. A new way to search and track the resonance frequency automatically is proposed, which based on phase, current effective value feedback and a variable step-size algorithm.(4) The circuit of system and performance have been tested, and the generated data has been analyzed briefly. Experimental results show that such DSP-based power control system can make the ultrasonic scalpel work in the resonance vibration situation. The design of software and hardware can achieve the basic function. The system is feasibility and practicability.