Design of a digitally controlled high-voltage power supply for isolation resistance measurement applications

Izolacijsko upornost materiala se običajno meri po UI-metodi, kjer merjeni izolacijski material predstavlja breme, ki je napajan z enosmerno napetostjo. Iz izmerjene napetosti in toka se nato izračuna električna upornost. Merilniki izolacijske upornosti vsebujejo visokonapetostni vir, katerega napetost neposredno vpliva na točnost meritve izolacijske upornosti. Glavni cilj naloge je realizirati poceni preprost in dobro reguliran enosmerni visokonapetostni vir za potrebe merjenja izolacijske upornosti z upoštevanjem zahtev in sredstev naročnika. Na začetku so predstavljene fizikalne lastnosti izolatorjev, osnovni principi meritev izolacijske upornosti in tipični problemi, ki se pri tovrstnih meritvah pojavljajo. Sledi podrobna statična in dinamična analiza vezja zapornega pretvornika navzgor, na podlagi katere so poiskani optimalni parametri ključnih komponent. Nadalje je opisan razvoj in implementacija regulacijskega algoritma. Na koncu sledi realizacija napajalnika in algoritma regulacije izhodne napetosti, ter podkrepljena s preizkusi na realnih aplikacijah.Insulation resistance of material is usually measured by UI method, where the measured insulating material represents load which is supplied by direct voltage. Electric resistance is calculated from the measured voltage and current. Insulation testers contain high-voltage source, the voltage of which directly affects the accuracy of measurement of insulation resistance. The main objective of the thesis is to implement a simple and cheap well-regulated high voltage DC source for measuring insulation resistance with regard to the requirements and resources of the client. At the beginning are presented physical properties of insulators, basic principles of measurements of insulating resistance and typical problems that occur in such measurements. Follows the detailed static and dynamic analysis of flyback converter, on the basis of which optimal parameters of key components were found. Furthermore, the development and implementation of control algorithm are described. Finally, follows the implementation of the power supply and output voltage regulations which are supported by experiments on real applications