Abstract: The invention relates to a method for protecting against over voltage that is simple to produce, economical, compact and is simultaneously effective against over voltage for a converter (8) provided for supplying an electric motor (1) comprising at least one motor phase (L1, L2, L3). Said converter comprises an electric intermediate circuit (10) and several half-bridges (13a, 13b, 13c) that are connected in parallel in the intermediate circuit and respectively comprise a circuit breaker (15a, 15b, 15c) on the high potential side and a circuit breaker (17a, 17b, 17c) on the low potential side, in addition to an intermediately connected phase connection (14a, 14b, 14c).

Abstract: The invention reduces the oscillation of the rotation speed regulator when stationary—despite low position resolution and a high minimum rotation speed resulting from this—by switching the closed-loop control structure, when the drive is moved into the nominal position, in which case the closed-loop control structure does not need to include a current regulator when stationary. The control voltage is predetermined directly by the rotation speed regulator (2′), which is in the form of a pure P-regulator. If the rotor is deflected, then dynamic negative feedback is carried out by differentiation (9) of the position (&phgr;). The position control loop (1′), which is at a higher level than the rotation speed control loop (2′), is in the form of a PI regulator in order that no permanent position errors can occur.

Abstract: The invention reduces the oscillation of the rotation speed regulator when stationary—despite low position resolution and a high minimum rotation speed resulting from this—by switching the closed-loop control structure, when the drive is moved into the nominal position, in which case the closed-loop control structure does not need to include a current regulator when stationary. The control voltage is predetermined directly by the rotation speed regulator (2′), which is in the form of a pure P-regulator. If the rotor is deflected, then dynamic negative feedback is carried out by differentiation (9) of the position (&phgr;). The position control loop (1′), which is at a higher level than the rotation speed control loop (2′), is in the form of a PI regulator in order that no permanent position errors can occur.