Mps Diode "soft Recovery" Principle Of The Simulation Design And Development Of Practice

In power electronic circuits,especially in switch mode power supplies circuits and motor drive circuits, higher operating frequency will greatly reduce the size of passive components (inductance and capacitance) and the power loss in them. The power switching diodes used in these circuits forward shorter reverse recovery time, lower switching losses. At present, most power switching diodes used in these circuits are still being the PIN structure fast and super fast recovery rectifiers. But common PIN diode doesn't have the "soft" reverse recovery performance, in it's reverse recovery process will arise bigger reverse peak current and higher reverse voltage, result in more power loss and electromagnetic interference (EMI), and poses a threat to stability of the main switching devices and diodes. Choose "soft recovery" fast recovery rectifiers can significantly reduce these adverse effects.Based on the detailed analysis of the physical process at recovery period of the high voltage PIN fast recovery diode used as a Free-Wheeling Diode (FWD) in power converter circuits, the key factor of "soft recovery " performance and"soft recovery factor"of faster recovery diodes is the excess carrier distribution profile stored in the drift region during the diode forward conduction.If the excess carrier distribution profile being like " the inverse trapezoidal" ,that the density of excess carrier near P+N-junction is lower than near the N+N- junction, the recovery characteristics of diode will be more"soft"and "soft recovery factor" will be more biger. Combined advantages of PIN diode and schottky diode,the Merged PIN/Schockey (MPS) diode having more fast and more "soft" reverse recovery characteristics, can satisfy the requirement of modern power electronic technology. The basic theory of MPS diode and the concept of it't soft reverse recovery characteristics is described in this paper.Through the computer sorftware simulation of device and research and development practice demonstrates the relationship between the MPS diode structure parameters and reverse recovery time, positive voltage drop and reverse breakdown voltage,the principle of design and manufacture MPS diode is proposed. And a soft recovery MPS diode has being developed ,which reverse operation votage reach 400V, positive current is 10A,reverse recovery time less than 50ns, "soft recovery factor" more than 1.2.