| 摘要 |
The invention relates to an electronically commutated motor (20) operated on a direct current source (UB), for example, a direct current intermediate circuit (46). The motor has a permanent magnetic rotor (28) and a stator having a stator winding phase (26) in which an alternating voltage is induced during operation by the permanent magnetic rotor (28). The motor further has an H-bridge circuit (22) comprising power semiconductors (T1 to T4). The circuit (22) has an upper bridge half (38) that is connected during operation to a pole (46) of the direct current source (UB) and a lower bridge half (56) that is connected during operation to the other pole (50) of the direct current source (UB). The stator winding phase (26) is disposed in the diagonal (24) of the H-bridge circuit (22) and, during operation, a current pulse flows through it, first in one direction and then in the other. One commutation process each occurs between two consecutive current pulses (i1, i1'). At the beginning of a commutation process, the currently conducting semiconductor switch of the one bridge half (38) is switched off in order to interrupt the energy supply from the direct current source (UB) such that a circulating current (i*; -i*) flows through the stator winding phase (26) in the other bridge half (56), the semiconductor circuit, which continues to be controlled in a conductive fashion, and a free-wheeling diode (58; 60) associated with the closed semiconductor circuit of this other bridge half. Said circulating current converts the energy stored in the magnetic circuit of the motor (20) at least partially into drive energy for the permanently magnetic rotor (28), thus adjusting to zero. Said current-free state of the stator winding phase (26) is detected in a sensor-free fashion by measuring the voltage (uind) that is induced in the stator winding phase (26) by the rotor (28). The previously conducting semiconductor circuit of the other bridge half (56) is blocked. The commutation process is completed in that a current is supplied to the stator winding phase (26) from the direct current source (UB) in a direction opposite to the direction in which the current was flowing before the commutation process. The invention further relates to a motor for performing such a method. |
