Ebm-Papst St. Georgen Gmbh & Co Kg

Henry Weissbach

Jens Loeffler

Arnold Kuner

Jens Löffler

An electronically commutated motor is operated from a DC voltage source (U), e.g. from a DC link circuit (). The motor has a permanent-magnet rotor () and a stator having a stator winding strand () in which, during operation, an alternating voltage is induced by the permanent-magnet rotor (). It further has an H-bridge circuit () having power semiconductors (Tto T). At the beginning of a commutation operation, the presently conductive semiconductor switch of a first bridge half () is switched off, in order to interrupt energy delivery from the DC voltage source (U), so that, in the other bridge half (), a loop current (i*; &#x2212;i*) flows through the stator winding strand (), through the semiconductor switch still controlled to be conductive therein, and through a recovery diode () associated with the blocked semiconductor switch of that other bridge half. This loop current converts the energy stored in the magnetic circuit of the motor () at least partly into driving energy for the permanent-magnet rotor (), and in that context the stored energy drops to zero. This currentless state of the stator winding strand () is detected in a sensorless manner by measuring the voltage (u) induced by the rotor () in the stator winding strand ().

Method of operating a single-stranded electronically commutated motor from a DC voltage source, and motor for carrying out such a method

An electronically commutated one-phase motor () has a stator having at least one winding strand () and a permanent-magnet rotor (). The rotor, as it rotates, induces a voltage (u) in the at least one winding strand (). The motor has an electronic calculation device (), preferably a microcontroller &#x3bc;C, which is configured to execute, during operation, the steps of a) sensing the value of the instantaneous operating voltage (Ub); (b) using the operating voltage value (Ub) and optionally further parameters, adjusting a time duration (T) of a switch-on current pulse (i) for the motor, in order to apply a consistent amount of electrical energy to the windings during start-up attempts, thereby maximizing the probability of successful start-up, regardless of possible fluctuations in motor operating voltage and related operating parameters. The switch-on current pulse duration (T) can be adjusted longer or shorter, as a function of operating experience.

One-phase electronically commutated motor

An electronically commutated one-phase motor (') has a stator having at least one winding strand (&#x2032;), and it has a permanent-magnet rotor () that induces, as it rotates, a voltage (u) in the winding strand. The motor further has an electronic calculation device or microcontroller () which is configured to execute, during operation, the following steps repetitively: sampling the induced voltage (u) in a currentless winding strand, for example, during a half-wave of the induced voltage, in order to obtain a plurality of analog voltage values; digitizing the analog voltage values in order to obtain a plurality of digitized voltage values; and processing the plurality of digitized voltage values to ascertain the instantaneous rotation direction of the motor rotor. The control circuit then can use these data to assure reliable motor start-up, regardless of any external driving forces which occur.

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Uhlingen-Birkendorf, Germany

Henry Weissbach