The Universal Motor is mainly composed of three parts: stator, rotor and bracket. The stator is composed of salient pole iron core and excitation winding, and the rotor is composed of hidden pole iron core, armature winding, commutator and rotating shaft. A series circuit is formed between the excitation winding and the armature winding through brushes and commutators.

The Universal Motor has the advantages of high speed, small size, light weight and convenient speed regulation, so it is used as the power source in most electric tools. It is widely used in power tools, garden tools, kitchen appliances and other product fields based on its features such as wide adjustable speed range, large starting torque, simple maintenance and low cost. Single-phase Universal Motor have frequent starting, high speed, large vibration, uneven load, etc., so higher requirements are put forward in terms of manufacturing quality.