Introduction to the characteristics and part of the structure of the DC motor

A brushless DC motor consists of a permanent magnet rotor, a multi-pole winding stator and a position sensor. According to the change of the rotor position, the position sensor commutates the current of the stator winding in a certain order (that is, detects the position of the rotor magnetic pole relative to the stator winding, and generates a position sensing signal at the determined position). The position is processed by the signal conversion circuit to control the power supply. The switch circuit switches the winding current according to a certain logical relationship). The operating voltage of the stator winding is provided by an electronic switching circuit controlled by the output of the position sensor.

Here is the list

• Position Sensors for DC Motors

• Permanent magnet DC motor

• Electromagnetic DC Motor

Position Sensors for DC Motors

There are three types of position sensors: magnetic, photoelectric and electromagnetic.

Brushless DC motors that use magnetic position sensors, whose magnetic sensor devices (such as Hall elements, magnetic diodes, magneto diodes, magnetic resistors, or application-specific integrated circuits, etc.) to detect changes in permanent magnets and rotor rotation in the magnetic field. A brushless DC motor using a photoelectric position sensor is equipped with a photoelectric sensor device at a certain position on the stator assembly, a shading plate is installed on the rotor, and the light source is a light-emitting diode or a small light bulb. When the rotor rotates, due to the action of the shading plate, the photosensitive element on the stator will intermittently generate a pulse signal of a certain frequency. BLDC motors with electromagnetic position sensors are equipped with electromagnetic sensor elements (such as coupling transformers, proximity switches, LC resonant circuits, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect causes the electromagnetic sensor to generate a high-frequency modulation signal (the amplitude of which varies with the rotor position).

Permanent magnet DC motor

Permanent magnet DC motors are also composed of stator poles, rotors, brushes, and casings. The stator poles are made of permanent magnets (permanent steel), including ferrite, AlNiCo, NdFeB and other materials. According to its structure, it can be divided into cylindrical type and tile type. Most of the electricity used by VCRs is cylindrical magnets, while most motors used in power tools and automotive appliances use special block magnets.

The rotor is generally made of laminated silicon steel sheets, and the number of slots is less than that of the electromagnetic DC motor rotor. Most of the low-power motors used in video recorders are 3-slots, and the high-end ones are 5-slots or 7-slots. The enameled wire is wound between the two slots of the rotor core (three slots have three windings), and its joints are respectively welded on the metal sheets of the commutator. Brushes are conductive parts that connect the power supply and rotor windings, and are both conductive and wear-resistant. The brush of the permanent magnet motor adopts single metal sheet or metal graphite brush, electrochemical graphite brush. The permanent magnet DC motor used by the recorder adopts electronic speed stabilization circuit or centrifugal speed stabilization device.

Electromagnetic DC Motor

Electromagnetic DC Motor Electromagnetic DC motor consists of stator poles, rotor (armature), commutator (commonly known as commutator), brushes, casing, bearings, etc.

Hangzhou New Hengli Electric Machine MFG. Co., Ltd. motor max-power reaches 15000kW (A.C. motor), 2800kW (D.C. motor), and max-center-high dimension of our motor reaches 1250mm.