FREQUENCY CONVERTER Russian patent published in 1999 - IPC

FIELD: conversion equipment, A C electric motor drives, sources of secondary electric power supply. SUBSTANCE: given frequency converter has intermediate D.C. element and power unit presenting bridge circuit built up on transistor keys. There is inserted protection of these keys against failure with emergence of through current in arm of bridge and during transition processes initiated by cut-off of converter. First one of these protections is realized by insertion of limiting resistor shunted by diode in series with capacitor of supply filter and second one - by feed of permission signal of converter from secondary winding of network transformer. Radiator with transistor keys is used as vertical wall of frame of converter. EFFECT: improved thermal characteristics, decreased mass and dimensions of converter. 1 dwg