Variable speed AC motor control system
US4618810A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 4, 1983 |
| Grant date | Oct 21, 1986 |
| Priority date | — |
| Expiry date | Feb 4, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P27/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
AC mains voltage input is directed to a bridge rectifier and converted to a DC voltage output. This DC power supplies an inverter which reconverts it to variable frequency AC output, used to drive a variable-speed AC motor. A microprocessor-based control unit generates firing pulses for SCR's in both the rectifier and inverter. It maximizes the efficiency of the rectifier by generating phase delay and sequencing data in advance of each line-to-netural zero-crossover of the AC mains voltage input; it makes the voltage and frequency of the inverter AC output both proportional to the value of the DC voltage output, enabling the system to maintain a constant volts/Hertz ratio between the AC output voltage and the AC output frequency. Appropriate fault protection circuits are included with the control unit to prevent fault conditions from damaging the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.