DC braking of inverter-driven AC motors
US4990844A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 18, 1989 |
| Grant date | Feb 5, 1991 |
| Priority date | — |
| Expiry date | Oct 18, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P3/24
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A DC braking system for an inverter-driven induction motor, (e.g., three-phase). When a braking command occurs, the normal gating sequence of the inverter stops. Mode 1 of the braking procedure starts. In Mode 1, two semiconductor phase switches of the group connected with one of the DC buses and the semiconductor switch of the third phase that is connected with the other DC bus are latched in a conducting state. The motor essentially receives DC current, which increases until it actuates a current limit device, clearing the latch. Then all six switches are turned off. That drives the motor current through the back-biased parallel diodes. The negative DC bus voltage is available to suppress motor current despite large motor speed voltages. The apparatus repeats the Mode 1 procedure for a predetermined time interval, after which Mode 2 of the braking procedure starts. In Mode 2, just as in Mode 1, two switches of one bus and one switch of another bus conduct until an overcurrent limit is reached. Then the one switch which is connected to a different bus turns off and its complement (same phase, other bus) turns on, allowing motor current to circulate in the motor windings. This allo…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.