METHOD AND EQUIPMENT FOR HIGH POWER DRIVING WITH THREE-PHASE INVERTER AND THREE-PHASE ASYNCHRONOUS MOTOR

摘要

The invention relates to a method and equipment for high power driving with a three-phase inverter for driving the three-phase asynchronous motors. According to the invention, the method consists in supplying a three-phase asynchronous motor with a multilevel three-phase voltage by using the PWM (Pulse Width Modulation) technique, so that the voltages upon the outlet from the inverter have a sinusoidal harmonics with a precision better than 0.2% and two minimum upper harmonics. According to the invention, the equipment contains upon the inlet a three-phase switch (1) with short-circuit protection, connected to a three-phase transformer (3) with two secondary windings in delta-connection and star-connection, respectively, the voltage outputting the transformer being applied to some serially connected three-phase rectifiers (3 and 4), made with semiconductor diodes, the direct current voltage obtained being then applied, by means of some capacitors (5 and 6), to a three-phase inverter (7) carried out with a multiple of six transistors IGBT, the three-phase inverter (7) being protected against short-circuit by blocking the operation of the transistors comprised therein and by the automatic command of two tyristors (8 and 10) connected in series with two current-limiting resistors (9 and 11), the three-phase voltages upon the output of the inverter (7) being filtered by a three-phase LC filter (12), in case of the normal operation the inverter (7) being checked, being put to supply, by means of a three-phase contactor (13), a set of resistors (14), and during the normal operation, there being connected another output contactor (15), the three-phase voltage upon the output thereof, being applied to a three-phase transformer (16), the voltage upon the output of the transformer (16) being applied to a three-phase asynchronous driving motor (17), the whole assembly thus formed being controlled by means of an equipment for controlling, adjusting and diagnosing the drive.