To answer the question of what a collector motor is, it is necessary to understand what is called an engine in general. And this is an electric machine, the reverse of the generator. Together the generator and the motor are called a DC machine . It is designed to convert mechanical energy into electrical energy (that is, to work as a generator) or vice versa - electrical to mechanical (to work as an engine). If we equip the DC synchronous machine with a collector, then we get a collector motor. In the generator mode, the collector will play the role of a rectifier, in the driving mode - the frequency converter. It is thanks to him that the alternating current flows through the armature winding, and the constant current in the external circuit.
From all of the above, it follows that the collector motor is an electric synchronous machine in which the rotor position sensor and the current switch in the windings are a brush-and-sewer assembly. Naturally, as already mentioned, it can simply become a generator.
The smallest collector motor (several watts) consists of such mandatory parts as a three-pole rotor, sliding bearings, a collector unit (it also consists of two copper plate-brushes), a two-pole stator on permanent magnets. The smallest devices of this type are used in some children's toys.
The collector motor of more power has, as a rule, a multi-pole rotor, rolling bearings, a collector unit on four graphite brushes, a four-pole stator on permanent magnets. It is the motors of this design that stand in cars, in fan drives, in cooling and ventilation systems, in pumps, janitors and so on. The main advantage of such a device as a collector motor can be called ease of operation, repair and manufacturing.
Powerful devices (for several hundred watts) contain stators on electromagnets. There are several basic ways to connect such windings: sequentially to the rotor (successive excitation, decent maximum torque, however fast idle speed), parallel to the rotor (so-called parallel excitation, which can be called the stability of the turns, however, the shortcomings include a small maximum moment ). There are also variants with mixed and independent excitement, however they are rarely used.
There is also such a machine as an AC motor. However, it can not be considered separately. Under such a machine is usually understood as a universal collector motor. This is a kind of machine that works on both direct current and alternating current. Such a device has become widespread in hand power tools and in some household appliances, due to its small size, weight, low price, ease of operation. Such a universal collector motor can be directly connected to the network, it has a small starting current, a simple control circuit.