What are the difficulties in the design of permanent magnet DC motors

Many people know that the permanent magnet DC motor in electric vehicles has always been paid attention and liked. Now electric vehicles have low pollution, save oil consumption, simple structure, easy maintenance and long service life, and are favored by countries all over the world. Compared with other types of micro motors of the same power, the permanent magnet DC motor is small in size, light in weight, and has obvious advantages in quality, efficiency, and price. It has no brushes and slip rings, and has a simpler structure and better performance. Reliable and adaptable to the environment, it is more suitable as a driving motor for electric vehicles. Since square wave power supply is generally used, under the same peak voltage and peak current, the torque generated by the interaction between the square wave current and the square wave magnetic field is larger, so the permanent magnet motor can output a larger electromagnetic torque.

　　 But how can people's needs be so little? People want more complete and lighter electric vehicles, so it is a big challenge for permanent magnet DC motors. Due to the limitation of the inner diameter of the wheel hub, the volume of the permanent magnet DC motor is limited, and a higher torque is required, which brings certain difficulties to the design of the micro motor. Moreover, its design cannot simply apply the method of permanent magnet synchronous motor, nor can it simply apply the method of DC motor. According to the characteristics, find a more accurate design method. Here, a design method combining magnetic circuit calculation and magnetic field analysis is used to study the three-phase permanent magnet DC motor.