Patent ID: 6243532
Filing Date: 2001-06-05
Classification: H02P,Y10S

Abstract:
A speed control device for an electric motor, the device comprising:controlled switch means for receiving a source voltage, said controlled switch means modulating said source voltage according to a switching signal, said switching signal having a frequency higher than a frequency corresponding to a time constant of the electric motor, said controlled switch means applying said modulated source voltage to the electric motor;regulation means for regulating said modulated source voltage to a voltage set value corresponding to a desired motor speed by varying said switching signal at the frequency higher than the frequency corresponding to the time constant of the electric motor;integration means for integrating said modulated source voltage occurring at terminals of the motor to form a motor voltage average value;comparator means for determining a deviation between said motor voltage average value and said set value;said regulation means varying a pulse width modulation of said switching signal dependent on said deviation, said integration means includes an analog to digital converter for converting said motor voltage average value to a digital value.