| Abstract |
An electronically commutated (EC) permanent-magnet motor has a higher efficiency than a singlephase
induction motor. In addition, EC motors have some further advantages: wide speed range and
easy speed controllability. If the latter features are not decisive, a highly efficient mains-fed ferrite
magnet synchronous motor represents an interesting alternative. An external rotor motor is especially
advantageous for fan applications enabling a compact impeller-motor-unit. However, it has a high inertia.
Therefore, direct-on-line starting is not applicable. The starting problem can be solved by the
proposed microprocessor controlled triac circuit. Once the rotor is synchronized, the motor is permanently
connected to the mains and operates with high efficiency at constant speed. This starter
circuit is less expensive, smaller and more temperature-resistant than the electronics of an EC motor. |
