Control device for induction motor
US5231339A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 18, 1991 |
| Grant date | Jul 27, 1993 |
| Priority date | — |
| Expiry date | Mar 18, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/72
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
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..
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.