CONTROL DEVICE FOR INDUCTION MOTOR

• Main Authors: SADAO ASABA, YASUHARU KISHIMOTO, SHIGEO KAWATSU, KENICHI NAKATA
• Format: Patent
• Language: English
• Published: 26.09.1991
• Edition: 5
• Subjects: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORSOR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRIC EQUIPMENT OR PROPULSION OF ELECTRICALLY-PROPELLEDVEHICLES; ELECTRICITY; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES, IN GENERAL; GENERATION; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; PERFORMING OPERATIONS; TRANSPORTING; VEHICLES IN GENERAL

In a slip frequency control system hitherto widely employed as a control system for an induction motor type electric rolling stock (in which a slip frequency is determined from a current deviation, an inverter frequency is calculated from the slip frequency and a motor rotation frequency, and the inverter frequency is multiplied by a predetermined correction factor to determine a modulation rate, thereby operating an inverter), a motor output torque decreases in a low speed region. It is difficult to make the correction for this decrease of torque by detecting the torque. In the present invention made considering that a torque curve and sin phi ( phi : the internal impedance angle of a motor) obtained from the result of simulation resemble each other, the decrease of sin phi is regarded as being the decrease of torque and a voltage to frequency ratio is corrected so as to compensate for the decrease of sin phi .