The DC power supply current flows along the positive pole of the power supply to the left brush. The brush and commutator rub against each other, and the current flows through the left commutator (also known as the commutator, this motor has two commutator blades) into the coil. It flows out from the right side of the coil, passes through the right commutator and the right brush, and returns to the negative pole of the power supply, forming a closed circuit.
Due to the coil being in the magnetic field of the main magnetic pole, it is subjected to electromagnetic force. Due to the different directions of current (the current on the left flows inward and the current on the right flows outward), the two sides of the coil are subjected to electromagnetic forces of the same magnitude and opposite directions. These two electromagnetic forces precisely form an electromagnetic torque. Under the pull of the electromagnetic torque, the coil begins to rotate. In a DC motor, the coil is embedded in the rotor slot, and the motor begins to rotate.
The left and right reversing pads rotate along the axis, while the electric brush remains stationary. After one revolution, the coil on the right moves to the left and the coil on the left moves to the right. However, due to the presence of the reversing pads, the current direction inside the coil on the left flows inward in the same direction as the current direction inside the coil on the left. Therefore, the direction of the electromagnetic force received remains unchanged, and the same applies to the right as well. So from a spatial perspective, the direction of electromagnetic force acting on the coil edge at the same position remains constant, ensuring the cyclic rotation of the motor.
However, when a coil is rotated to different positions, the magnetic field is not the same, which results in the electromagnetic force acting on the coil constantly changing. Therefore, the coil rotates unstable, fast and slow. So, installing multiple coils can ensure even and stable force distribution on the coils.
Characteristics of DC motors
1. High operating efficiency, due to the small obstruction force of the motor when working without load, it has high operating efficiency and stable performance, which can ensure high efficiency and long-term operation;
2. The starting current is very small. When the rotor is idling, the magnetic field has already formed on the rotor, and it only operates normally without the need for starting current;
3. Easy to control, it can be controlled using a frequency converter or control board according to the initial situation, enjoying the stability of constant period control.
Advantages of DC motors
1. High driving power: DC motors can rotate relatively large mechanical loads, providing greater power output and better impact resistance than AC motors of the same capacity;
2. Stable and reliable work: Stable operation, especially suitable for long-term continuous work, work efficiency is independent of moisture exposure;
3. Controllable control: Various circuits such as frequency converters, control boards, and sliders can be used to control stable speed, achieving constant speed control. Compared to other motors, it is more stable and reliable.