Research On Electrical Life Model For A Dc Bridge-type Relay And Its Application

High voltage and high power is the current development direction of electromagnetic relay.As a typical representative of high-power electromagnetic relays,DC bridge-type relay is widely used in aerospace,defense,new energy and electric vehicles and other fields.In recent years,the breaking voltage and current level of bridge-type relay have been further improved.The problems of low reliability and short life have become the urgent problems in the field of relays.In this paper,A DC bridge-type relay is used as the research object to study the influence of design parameters on its performance degradation process,and its electrical life model is established to provide an effective reference for the design and life prediction of long life relay.Firstly,according to the structural characteristics of the DC bridge-type relay,the overall design of the experiment platform is determined.The mechanism and the parameter measurement part of the relay simulating device are respectively designed to realize the adjustment of the contact distance and pre-pressure.And the displacement of movable contact and the electrical parameters are collected and stored.Then,the dynamic characteristics are studied based on the experiment platform.And the velocity curve of the movable contact is obtained by displacement curve and differential method.After studying the effects of overtravel and pre-pressure on the breaking speed and rebound,the overtravel,pre-pressure and magnetic induction intensity for arc blowing of relays to be used in the subsequent process are determined.Secondly,the failure mechanism of the DC bridge relay is analyzed and the type of failure of the bridge relay and the cause of the failure are clarified.Under the condition of 270V/200 A and resistive load,the bridge relays with different parameters are tested.According to the contact voltage,the contact current and the coil current waveforms of the whole life process,the methods of extracting the characteristic parameters are determined,and the extracted characteristic parameters are analyzed and compared to determine the characterization parameter of the electrical life.After that,the orthogonal experiment is designed and according to the theory of multiple regression analysis,the electrical life mathematical model and the electrical life prediction model based on the three parameters are established.Finally,the life model is applied to the relay life prediction,and the implantable life prediction module is designed.Firstly,the overall design of the life prediction module is determined according to the input parameter of the life prediction model.Secondly,the sensor unit,the energy storage circuit and the data storage circuit of the life prediction module are designed according to the electrical life characterization parameter.Finally,the program of microcontroller and the software of computer are designed.And the residual life prediction,data read,data storage and data analysis functions are achieved.The electrical life model and life prediction model based on design parameters can be applied to the design and predict residual life of bridge-type relays,and provide an effective reference for the establishment of life models for other kinds of relays.