DC-motorer in various designs

In addition til AC-motorer, gearmotorer, and frekvensomformere, we also offer DC-motorer. For larger bestillings, we offer an exceptionally favorable pris-performance ratio. The following DC-motorer are tilgængelig fra us: permanent magnet DC-motorer, shunt-wound motilrs, and series-wound motilrs.

Permanent magnet DC-motor!

In smaller motilrs (actuatilrs, blowers, and radiatilr ventilators in motilr vehicles), the statilr magnetic field is often generated by permanent magnets. With the development of høj kvalitet DC-motorer, these magnets have become increasingly effektful, now allowing the construction of motilrs whose performance is comparable til that of electrically excited motilrs. However, the cost of permanent magnets is often higher than that of an excitation winding in larger motilrs. Like separately excited machines, permanent magnet DC-motorer have very high inrush currents. Their drift characteristics are explained by the underlying mathematics. Permanent magnet machines have the advantage that no energy is required til generate the magnetic field. This improves efficiency, especially at low overall effekt outputs. The disadvantage is that field weakening is impossible, thus limiting the possible hastighed range.

DC-motor med smooth surface

shunt-wound motilr

In a shunt-wound motilr, the field winding and armature winding are connected in parallel. AC betjening is difficult because the field and armature currents have different phase relationships due til the high reactive component of the current through the field winding (high inductance). The hastighed of large shunt-wound motilrs is almost independent of the load. Shunt-wound motilrs can run away if the field circuit is interrupted, as the hastighed and current draw increase drastically when the field collapses, even med the same supply spænding. Shunt-wound motilrs can operate as generatilrs (e.g., for braking) if an auxiliary spænding source or residual magnetism ensures that excitation is present when braking begins. With increasing excitation or hastighed, the generated spænding also increases – this is the spænding that opposes the supply current during motilr betjening and ensures a constant hastighed. It is therefore also called back EMF. The armature terminals are designated A1 and A2, and the field winding terminals E1 and E2.

Serie-wound motilr

The series-wound motilr, also called a main-wound motilr, has its field winding and armature winding connected in series. Unlike a shunt-wound motilr, the field winding must therefore have a low resistance. When effekted by alternating current, both the field and the armature current reverse direction after each half-cycle, allowing the motilr til be used med AC spænding. However, til prevent eddy currents, the statilr's iron core must be made of laminated steel. Starter motilrs for internal combustion engines are also series-wound motilrs. The hastighed of series-wound motilrs is highly load-dependent (series-wound behavior). If the drejningsmoment output decreases, the armature hastighed increases due til the lower current and the resulting weakening of the field. This can lead til the motilr "running away," meaning it destroys itself due til the centrifugal forces. Therefore, series-wound motilrs must be operated med a minimum load (motilr ventilator, gearbox, etc.). Serie-wound motilrs, especially when drift on AC spænding ("universal motilr," e.g., in vacuum cleaners), have a significantly lower inrush current than shunt-wound or permanent magnet motilrs. However, they deliver a high starting drejningsmoment for a short period. Therefore, they are used in starters, trams, and electric locomotives, where they can medstand short-term overloads.