Permanent magnet motor is an attempt to reduce the weight and overall dimensions of the electric machine, simplify its design, improve reliability and ease of operation. Such an engine allows you to significantly increase the efficiency (efficiency). He received the greatest distribution as a synchronous machine. In this device, permanent magnets are designed and used to create a rotating magnetic field.
At present, a combined version is used: permanent magnets together with electromagnets, through the coil of which a direct electric current flows. Such combined excitation provides many positive aspects: obtaining the required voltage and speed control characteristics with a decrease in excitation power, reducing the volume of the magnetic system (and, as a result,the cost of a device such as a combined permanent magnet motor) compared with the classical electromagnetic excitation system of a synchronous machine.
Today, the use of permanent magnets is possible in devices with a power of only a few kilovolt-amperes. However, improved permanent magnets are being developed, and the power of the machines is gradually increasing.
A synchronous machine as a permanent magnet motor is used as a direct motor or generator in drives of various capacities. Such devices have found application and distribution in mines, metallurgical plants, and thermal power plants. Since the synchronous motor operates with a wide variety of reactive power, it is used in refrigerators, pumps and other mechanisms with a constant speed. A permanent magnet motor is used in low-power devices and devices where strict and precise speed constancy is needed. These are automatic recorders, electric clocks, program control devices, etc. At stations and substations, special synchronous generators are installed that produce only reactive power in idle mode. Such power is used for induction motors, and synchronous machines of this type are called "compensators".
The principle of operation of a machine such as a permanent magnet motor, and, in particular, a synchronousmotor, is based on the interaction of the magnetic field of the rotor (moving part) and the stator (stationary part).
Thanks to the interesting and not yet fully understood properties of magnets, inventions based on them often appeared and appear. For example, one of the most common ideas is the creation of such a device as a fuel-free perpetual motion machine with permanent magnets. From the point of view of modern science and physics, a perpetual motion machine is impossible (it would have to have an efficiency greater than one, and this is considered unrealistic), but inventors in the field of alternative energy do not lose hope for the creation and development of such a discovery.
