Design And Research Of A New Type Of Electromagnet With Permanent Magnet

Pneumatic steering gear is widely used as an actuating element in medium-rangeand short-range missiles’ attitude adjustment. Electromagnet is a critical component ofthe electromagnetic valve in the pneumatic steering gear. By controlling the action andrelease of the electromagnet, the gas circuit can be switched, thus to control the twirl ofpneumatic steering gear, and control the attitude adjustment of the missile. Therefore, theperformance and reliability of electromagnet can affect the accuracy of the missiledirectly.For the quondam electromagnet in one type of pneumatic steering gear, the coilshould be energized continually to keep the suction state, which lead to high powerconsumption and temperature rise, thus effecting the force performance of theelectromagnet and also the reliability of the pneumatic steering gear. Aiming at thisproblem, this paper redesigned the electromagnet, used permanent magnet in theelectromagnet, achieved the functions of permanent magnet flux holding and coilmagnetic flux acting. The redesigned electromagnet meeted the requirements of forceperformance and dynamic response time, reduced power consumption and increased thereliability at the same time.Firstly, the structure of the electromagnet was redesigned, three schemes werepresented. Equivalent magnetic circuit model of all schemes was builded. To meet thedemand of suction retaining force, the permanent magnet’s size was confirmed bycalculating with the equivalent magnetic circuit.The static electromagnetic attractiveforce was calculated with the equivalent magnetic circuit, the result was compared withthe demand, thus comfirmed the feasibility of each scheme and the best scheme waschoosed as the implement scheme.Secondly, using finite element software ANSYS, builded the3D finite elementmodel of the implement scheme’s electromagnet. The static characteristics of theelectromagnet was simulated. The static force in0ampere-turn, pull-in ampere-turn anddrop-out ampere-turn was calculated accurately with finite element method from thepoint of magnetic field. The comparison between simulation result and index requestshowed the feasibility of the scheme. The dynamic characteristics was simulated by thefinite element software FLUX, the curve of displacement, velocity, acceleration,attractive force of armature and the voltage and current of coil in pulling-in process wasobtained. The dynamic response time meeted the request, thus proved the the feasibility of the scheme further.Thirdly, to promote the force performance, dynamic response time and powerconsumption, some structure parameter was optimized. By using virtual prototypetechnology, through parametric modeling, those parameter were assigned a series ofdiscrete value respectively. Then the static attractive force in parameters’ different valuewas calculated through finite element simulation. The results was compared to each other,and the best value for each parameter was selected.Then, tolerance design was done in the electromagnet’s design process, to promoteit’s noiseproof feature and stability of quality, thus to promote it’s reliability. Theexperiment program of tolerance design was made, the static attractive force when theerror factors was in different valnue level was also calculated through ANSYS. Statisticalanalysis of the results was done though contributive rate analysis, the factors which effectthe product performance fluctuation seriously was found. At last, the best tolerance rangeof all error factors was comfirmed after an overall consideration.Finally, a prototype was manufactured. The experimental results verified theelectromagnet designed can meet the the requirements from the point of forceperformance, dynamic response time and operation life.