Motor control system for variable speed induction motors
US5828200A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 1995 |
| Grant date | Oct 27, 1998 |
| Priority date | — |
| Expiry date | Nov 21, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P23/0004
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A control system for a multiphase induction motor includes microcontroller control means providing a variable frequency signal and deriving high side/low side phase signals from the variable frequency signal. Power is applied from an AC/DC converter to the motor by an output drive bridge with three pairs of high side/low side semiconductor switches, one pair for each phase. The high side and low side phase signals are applied through high side/low side driver means to control the switches and effectively apply a quasi-square waveform to the motor windings. The motor and the control system electronics are protected from excessive current levels by current sensing means. When the current exceeds a predetermined level, the microcontroller limits the power drawn by the motor by ramping down the variable frequency to lower the speed of the motor. In case the motor or control electronics overheat, a temperature sensor is monitored by the microcontroller to shutdown the motor. When the motor is started, current inrush is avoided by modulating the phase signals during a start up period. The duty cycle of the modulation is gradually increased in steps until a duty cycle of 100% is reached a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.