Patent ID: 6812658
Filing Date: 2004-11-02
Classification: F01P,F04D,H02P,Y02B

Abstract:
A drive unit, in particular for a fain in motor vehicles, comprising an electric motor (12) operated on a DC line, and comprising a device (13) for controlling the speed of the motor (12) by changing the operating voltage applied at the motor (12), wherein the device (13) comprises a plurality of resistors, R1-R3, and a plurality of semiconductor switches, T1-T3, selectively connecting the motor (12) in series with at least one of the resistors, R1-R3, wherein for n+1 speed levels, the device (13) comprises n series circuits each having one resistor, R1-R3, and one semiconductor switch, T1-T3, and having one further semiconductor switch, T4, connected in series with the motor (12) to the DC line, UBat, and wherein each of the n series circuits is connected in parallel with the semiconductor switch, T1-T3, of the series circuit for the subsequent speed level, and the last series circuit is connected in parallel with the further semiconductor switch, T4.