The working principle of a coreless motor mainly utilizes electromagnetic induction. Specifically, when an external current is applied to the stator, a rotating magnetic field is generated on the stator. This rotating magnetic field interacts with the iron core beams and magnets on the internal rotor, causing the internal rotor to rotate. Because the internal rotor is hollow, sensors and other devices can be installed inside, enabling more flexible and diverse control functions.
A coreless motor mainly consists of a stator and a rotor. The stator is usually made of permanent magnets or electromagnetic windings and is located in the inner ring of the motor, while the rotor is made of an iron core with coil windings and is located in the outer ring of the motor.
This unique rotor structure gives the hollow cup motor the following characteristics:
Energy-saving features: Due to the elimination of energy loss caused by eddy currents formed in the iron core, the hollow cup motor has a very high energy conversion efficiency, with a maximum efficiency of generally over 70%, and some products can reach over 90%.
Control characteristics: Coreless motors feature rapid starting and braking performance, extremely fast response speed, and a mechanical time constant of less than 28 milliseconds, with some products achieving less than 10 milliseconds. Furthermore, within the recommended operating range and at high speeds, the speed can be easily and sensitively adjusted.
Stable operating characteristics: Due to the significant reduction in rotor weight and moment of inertia, the coreless motor can reduce the mechanical energy loss of the rotor itself, resulting in more stable operating characteristics.
Compared to traditional brushed DC motors, coreless motors have the following characteristics:
Reduced motor iron losses: Traditional brushed DC motors generate eddy currents in the iron core during operation, resulting in significant iron losses. However, in coreless motors, since there is no iron core, iron losses can be greatly reduced or even ignored.
Increased number of commutator segments: Traditional brushed DC motors typically have only 3 to 5 commutator segments, while coreless motors generally have 9, 11, or 13 commutator segments.
Reduced rotor inertia: Traditional brushed DC motors generally have a large inertia due to the presence of the iron core, while the hollow cup motor has a significantly reduced rotor inertia for the same size because the rotor is a cup-shaped, self-supporting coil.
Reduced coil inductance: Due to the absence of an iron core, the coil inductance of a coreless motor is much smaller than that of a conventional brushed DC motor of the same size.
Coreless motors have a wide range of applications, mainly including the following:
Fast-response servo systems include: rapid adjustment of missile flight direction, servo control of high-magnification optical drives, rapid autofocus, highly sensitive recording and detection equipment, industrial robots, and bionic prosthetics.
Products that require smooth and sustained drag for their drive components: such as various portable instruments and meters, personal equipment, field equipment, electric vehicles, etc.
Various types of aircraft: including aviation, aerospace, and model aircraft. Utilizing the advantages of coreless electric motors—light weight, small size, and low power consumption—the weight of the aircraft can be reduced to the greatest extent possible.
Various household appliances and industrial products: Using coreless motors as actuators can enhance product quality and performance.
It can be used as a generator or tachogenerator, taking advantage of its linear operating characteristics.
In situations where mechanical assistance is needed: with a speed reducer, it can also be used as a torque motor.
Coreless motors, as high-performance miniature servo DC motors, have broad application prospects. With the continuous advancement of technology and the rapid development of industrial automation, coreless motors will be used in even more fields.
With the widespread adoption of industrial robots and automated equipment, coreless motors will find broader applications in the robotics field. Robots require high-precision, fast-response drive components, and coreless motors, with their excellent control and stable operation characteristics, can meet various robot needs. With the rapid development of new energy vehicles, coreless motors will also find wider applications in the electric vehicle sector. Electric vehicles require lightweight and efficient drive components, and coreless motors, with their advantages of light weight, small size, and high efficiency, can effectively improve the performance and range of electric vehicles. With the continuous advancement of medical technology, coreless motors will also find wider applications in the medical equipment field. Medical equipment requires high-precision, stable, and reliable drive components, and coreless motors, with their excellent control and stable operation characteristics, can meet the needs of medical equipment.
