Research On 270V DC Solid-state Power Controller

Solid-State Power Controller(SSPC)is a switching device composed of semiconductor devices.It has the characteristics of no mechanical contact,no arc,fast response,low electromagnetic interference,long working life and high reliability.At the same time,solid-state power controller has built-in-test(BIT)interface,which facilitates the digital management of complex distribution system and improves the reliability of the system.It is one of the important components of modern aircraft power supply system.The main contents of this paper are as follows:Firstly,by discussing the principle of the DC solid-state power controller,the functional modules and the functional relationship between the modules are analyzed.The current detection methods suitable for 270 V DC solid-state power controller are studied,including resistance sampling detection and Hall effect detection.By simulating the over-current protection characteristics of circuit breaker,the mathematical model of over-current protection of solid-state power controller is established,and the calculation and simulation are carried out.The working characteristic tables and characteristic curves of rated current,1.25 times of over-current,2 times of over-current and 3 times of over-current are analyzed.Optical coupler and isolation transformer,which are key components of isolation for 270 V DC solid-state power controller driver circuit,are studied.The key power devices in power output circuit are studied: Bipolar Junction Transistor(BJT),Insulated Gate Bipolar Transistor(IGBT),Metal-Oxide-Semiconductor Field-Effect Transistor(MOSFET).Secondly,the circuit of 50 A high-power 270 V DC solid-state power controller is designed,including power supply circuit,emergency control circuit,state output circuit,MCU main control circuit,output and switch detection circuit,isolation drive circuit,short-circuit protection and overvoltage protection circuit,current detection circuit,voltage detection circuit and timing control circuit.The function of each circuit and the performance index of key components are analyzed.Detailed structural design,including layered structure construction,structural material selection,finished product weight prediction.Detailed thermal design,including temperature rise calculation based on the overall heat dissipation of the box,and thermal simulation analysis of working environment temperature at 25,55 and 85 ~C.Software design,including the formulation of internal and external circuits between the signal relationship and identification number,and the preparation of detailedcommunication protocols.Finally,a 270 V DC solid-state power controller test platform is built to test the prototype according to the performance parameters of the proposed research objectives.According to GJB/Z 299C-2006 Manual for Reliability Prediction of Electronic Equipment,a mathematical model is established.The average time between failures(MTBF)of reliability index is estimated to be 22866 h.Referring to GJB1515 General Specification for Solid Relay,the test items are drawn up and tested.The main test items are temperature cycle,mechanical impact,load condition test,aging,temperature cycle,moisture resistance,salt spray and life span.When the confidence level is 0.95,the MTBF is 28627 h,which is close to the reliability prediction value.By comparing the two data,it lays a foundation for further improvement and practical application of the product.In this paper,a 50 A high-power 270 V DC solid-state power controller is designed,and the prototype is developed,tested and analyzed.It has a certain reference significance for the research and production of solid-state power controller.