The Design Of Intrinsic Safety Ultrasonic Ranging System

Ultrasonic wave has no effects from light, anti electromagnetic interference and other advantages in high humidity, strong corrosion and dusty all kinds of special industrial fields, such as the material level measurement, manipulator control, reversing radar and robot obstacle avoidance. In flammable and explosive environment, ultrasonic ranging technology has many applications,such as in the coal mine, chemical and other combustion blasting dust and the flammable and explosive gas environment. Electrical and electronic equipment must be explosion-proof design to meet the needs of production safety.The harm degree depends on the ignition source storage size of energy release.When the device in the circuit stored energy release is higher than that of substances in the environment of minimum ignition energy, ignition and blasting dust and gas in the environment, resulting in fire and explosion accident.Explosion-proof design is an effective means to solve the risk, which is the most widely used installation of explosion-proof enclosure, but this method has problems of high cost, heavy and poor reliability. Intrinsically safe design is just to solve the problem of explosion-proof enclosure, omitting the complicated structure and intrinsic safety, light weight, small size, low cost and many other advantages. The plan becomes the first choice for coal mine electrical andelectronic equipment design.The existing ultrasonic drive theory and method restrict the flammable and explosive environment. Due to mechanical energy electric energy conversion efficiency is limited, various types of ultrasound system work in the mine,driving ultrasonic transducers need to provide larger power supply voltage.Traditional method is using voltage driven. Traditional method is using transformer drive. Due to the week in the transformer primary and secondary windings of a transformer, current flowing through the coil produces high energy storage above substances in the environment of the minimum ignition energy, which ignited the flammable and explosive gas coal mine resulting in accidents.For this purpose, we have carried out the research on the corresponding boost technology to replace the traditional mid cycle boost technology, which meets the essential safety requirements when the voltage of the ultrasonic transducer is reached. Due to the intrinsically safe driving in ascension for safety performance of the system at the cost of the need to sacrifice some ability to drive, therefore to improve intrinsically safe driven conversion efficiency is the urgent problem.Ultrasonic transducer system overall conversion efficiency mainly depends on the efficiency of power transmission, mechanical transmission efficiency and electromechanical conversion efficiency. The important index of mechanical energy and electric energy conversion efficiency is the electromechanicalcoupling coefficient of piezoelectric crystal materials. Piezoelectric crystal by using multi technology already hasten is mature PZT press ceramic electric,pressure electric material itself in the ultrasonic ranging system, especially electromechanical coupling coefficient to enhance the efficiency of the space is very limited. Therefore, intrinsically safe driving energy conversion efficiency can be improved by the transmission of electrical energy and mechanical energy transmission to achieve. Therefore, study of intrinsically safe ultrasonic driving impedance matching in order to achieve implementation and coordination between electrical matching transmission and mechanical transmission matching can improve the energy conversion efficiency of ultrasonic transducer system.Analysis short circuit release energy of the buck boost circuit in continuous current mode(CCM) and current period continued mode(DCM) draw the maximum short-circuit current of buck boost circuit to drive ultrasonic transducer load.As intrinsically safe circuit basis to judge, we can obtain intrinsically safe buck boost voltage booster circuit parameters. Subsequently to the intrinsically safe buck boost circuit as the output, through the analysis of the ultrasound system driving method and circuit of transducer used in coal mine,the characteristics of the environment, we can sum up two intrinsically safe type ultrasonic driving method on the ultrasonic driving. Finally, the corresponding circuit design for two kinds of driving mode and for each of the corresponding ultrasonic impedance matching parameters of drive circuit design, in order toachieve the best energy conversion efficiency.Finally, by calculating the maximum energy storage of the total circuit, the design of the ultrasonic echo processing circuit, display circuit and other software and hardware circuit, which can meet the requirements of the energy storage, realize a kind of intrinsically safe ultrasonic ranging system. At last, for the test waveforms compared with the provisions of GB minimum ignition energy of Ultrasonic ranging system which is intrinsically safe, under normal condition and fault condition, we can draw the conclusion the ultrasonic ranging system conforming to the safety requirements.All kinds of ultrasonic distance measuring equipment used in the dangerous environment have the common technology, so this research can provide reference for the design of Intrinsic safety.