Electronically commutatable motor

Abstract

An electronically commutable motor, whose excitation windings can be fed with current via semiconductor output stages from an electronic control unit using pulse-width modulated control signals and, in this context, which generate a rotating field in the stator of the motor, the rotating field placing the permanent magnet of the motor in rotational motion. Without position sensors, a reliable start-up in the rotational direction is achieved even given a high mass moment of inertia, a small cogging inertia, and poor damping such that, during the start-up of the motor, the control unit, during a specific or specifiable start-up phase, drives the semiconductor output stages in overlapping control phases using PWM control signals, whose pulse-width ratio rises from a minimum to a maximum and then falls again to the minimum, that the overlapping areas of the control phases in the affected excitation windings generate currents which yield a virtually continuous torque curve, and that, in the start-up phase, by shortening the commutation time between the control phases, coming after one another, the commutation frequency and thus the rotational speed of the motor is increased.