Ebm-papst St. Georgen Gmbh & Co Kg

Walter Heydrich

Hermann Rappenecker

Alexander Hahn

Wilhelm Weisser

The invention concerns a method for operating an electronically commutated motor () that is equipped with a current limiting arrangement which acts on a PWM controller (). The latter, in operation, delivers PWM pulses () having a controllable pulse duty ratio (pwm) and a substantially constant frequency. In the event a predetermined upper limit value (I; I) of the motor current (I) is exceeded, the current limiting arrangement effects a change in this pulse duty factor (pwm) in order to reduce the motor current (I). If the motor current (I) exceeds a predetermined upper limit value (I; I) while the motor () is rotating, that limit value (I; I) is raised by a timing member () during a predetermined time span () (FIG.: I), so that the available motor power is temporarily raised in the context of a load peak. If the rotor () is stalled, the limit value (I) is not raised but instead is greatly lowered. The limit value (I) is preferably raised as a function of the rotation speed of the motor () in order to utilize the improved motor cooling at high rotation speeds. At start-up of the motor (), the limit value (I) is briefly increased to a high value in order to enable dependable starting.

Method for operating an electronically commutated motor, and motor for carrying out one such method

An electronically commutated DC motor comprises a stator comprising at least one stator winding (), a rotor () electromagnetically interacting with the stator, a positive and a negative DC voltage line () for supplying power to the motor (), in particular from a battery (), a full bridge circuit () for controlling the current in the at least one stator winding (), which full bridge circuit () comprises a plurality of bridge arms that each comprise an upper bridge transistor () for controlling the current from the positive DC voltage line () to an associated terminal () of that stator winding () as well as a lower bridge transistor () for controlling the current from the relevant terminal of the stator winding to the negative DC voltage line (). The motor further comprises an arrangement for generating a plurality of rotor position signals, and an arrangement for controlling a predetermined bridge transistor by logical combination of rotor position signals associated therewith, there being provided, for logical combination of those rotor position signals, a control transistor () to whose base a first rotor position signal (H) is conveyable and to whose emitter a second rotor position signal (H) is conveyable, and whose collector signal serves to control the predetermined bridge transistor (). A circuit comprising a half bridge is also described.

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Georgen, Germany

Walter Heydrich