A Study For The Magnetic Generator Speed Control Based On MRF/MRG

Magnetic-electric generator used for fuze is a physical power,which uses ballistic air pressure as the driving force and can be appied for mortar projectile and electronic time fuze.Because the velocity of bullet changes linearly with the generator speed,also the generator speed relates to the output voltage,so the output voltage of the generator changes with the velocity of the projectile,reaches the maximum in the vicinity of the muzzle,followes by with speed reduction.Because the generator working in high speed will make the rotor parts(bearings,spindle,etc.)damage,and the output voltage is too high,which will make the fuze electronic components break down.Therefore,we must study speed control method,control the generator speed under high velocity bullet less than the limit speed of the bearing,output voltage less than the voltage value of fuze circuit,ensuring that the magnetoelectric generator can work reliably under high velocity bullet.Based on the analysis of the research on the speed control method of the generator at home and abroad,this paper puts forward a method of speed control based on the negative feedback of voltage.Speed control mainly through the speed control circuit and speed control device to achieve.Speed control circuit is based on a voltage negative feedback principle,and voltage negative feedback principle is that when the generator speed is higher than the limit speed of the bearing,the excess energy conver as damping torque on the shaft to limit rotating speed.The speed control device consists of a base,an excitation coil and a MRF/ MRG.MRF/ MRG as the executive component of rotational speed control is a kind of intelligent material which can be controlled by the magnetic field strength.Because the ferromagnetic particles easily get settled as long-term storage in MRF,we prepared MRG,and studied their rheological properties.We analyzed the cylindrical shear model,established the damping torque equation,and determined the damping torque calculation formula.We set up an experimental platform to test the speed control performance,and results showed that this technology was able to control the rotational speed effectively using MRF/MRG,will eventually be able to the speed of the generator could be effectively controlled from 10000 r/min to 5714 r/min.