| Integrated low voltage apparatus is a novel intelligent apparatus. ILVA adoptselectromagnetic configuration which makes it have a good likeness of contractor and usesimbedded computer as core. By means of power electronic technology, it integrates the totalfunctions of contactor and circuit breaker. This product has been passed the proof-tests andput into product.Although ILVA makes many useful attempts on the research on intelligent andintegrated technology, the intelligent unit is still needed to improve. Firstly, there are only twokinds of protections: three-phase over-current protection and starting protection. Furthermore,the kinds of protections can not be chosen flexibly by users. Secondly, Communication abilitycan not satisfy the demand of industrial application. Lastly, LED now used can not provide aperfect human computer interaction environment. Based on the first-generation ILVA, thedissertation is focused on the research on intelligence and information technology that areapplied to the second-generation ILVA.The dissertation has analyzed the common faults of the squirrel-cage three-phaseasynchronous motor at first. Through testing over-current amplitude value, negative-sequencecurrent and zero-sequence current, criteria has been drawn and different protective measuresare present in the dissertation based on symmetrical component method. Finally, it hasrealized different kinds of protections, such as short-circuit protection, rotate-stop protection,over-current protection, three-phase unbalanced protection, leakage protection and start-upprotection and so on. By the debug and operation, this method can simplify the hardwaredesign and realize the multifunction of protection on the premise of acceptable precision.CAN bus is applied in the motor protection system in the dissertation. The single ILVAis regarded as the slave computer of which communication software uses PIC assemblylanguage and PC as the host computer of which communication software uses Delphiprogramming language. The dissertation uses PIC18F2580 as the core processor to design the hardware circuitincluding A/D sample circuit, digital signal processing circuit and communication circuit. Atthe same time, LCD is applied to perfect the design of display output and key input circuit.According to the hardware design, software is programmed which makes the ILVA have aperfect human computer interaction environment. |
