Patent · US Expired

Speed control for a universal electric motor

US4134038A · kind A · utility

3Cited by

3References

9Claims

0Family size

Assignee

Robert Bosch GmbH · DE

Inventors

Wolfgang Kosak · Asperg, DE
Peter Werner · Wiernsheim, DE
Hans Gerber · Burghausen, DE
Ivan Hidveghy · Zuchwil, CH

Key dates

Filing date	Jan 16, 1978
Grant date	Jan 9, 1979
Priority date	—
Expiry date	Jan 16, 1998

Classification

Technology area (CPC H)Electricity
CPC primaryH02P25/14
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

A first thyristor, under control of a speed setting provided in an RC circuit varies the phase duration of current supply to the motor during positive halfwaves of the a c supply, and a second thyristor controlled in accordance with the motor current provided through the first thyristor determines the phase angle during which current flows through the motor in the negative halfwave of the voltage supply, so as to maintain the speed at the set value under varying conditions of load. During positive halfwaves, a capacitor is charged to a voltage corresponding to the amount of current flow through the motor and during the following negative halfwave, the charge is increased at a rate set by an RC circuit, resulting in turning on the second thyristor early under heavy load conditions, and late under light load conditions, and indeed not at all under idling conditions.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.