What are the Advantages and Disadvantages of Coreless Micro Motor?

Merit

1) High power density: the design of no core rotor is adopted. Compared with the iron core rotor of the traditional motor, the loss of no core rotor is smaller, and under the same torque, the power density is higher. The design of structure makes the space utilization rate of core micromotor higher and can carry higher power in a smaller volume. At the same time, the structure can also effectively reduce the weight of the motor. New manufacturing technology is adopted in the manufacturing process to make the overall structure of the motor more compact and efficient. In this way, the motor can improve the power density by effectively using the space. The power density of micro motor is the ratio of output power to weight or volume, no core rotor is lighter than ordinary no core rotor, which eliminates the eddy current and hysteresis loss generated by no core rotor, improves the efficiency of micro motor, and ensures higher output torque and power;

2) High efficiency: the reason for the high efficiency of micromotor is no core rotor without eddy current loss and hysteresis loss, and the resistance is very small, which reduces the copper loss;

3) No torque lag: because there is no magnetic field hysteresis between the rotor and the stator of this motor. Theoretically, the motor will have the torque hysteresis only when the magnetic field hysteresis exists between the rotor and the stator. And the rotor and stator of the motor are directly generated through the current, so there is no torque hysteresis. Because there is no core rotor without hysteresis loss, the fluctuation of rotation speed and torque is reduced;

4) Trough effect: This is mainly because there are some differences in the bearing matching precision, material quality, process and other aspects of the coreless micromotor, and these factors will have different degrees of impact on its manufacturing quality and use effect. Ordinary micromotor in the interaction of the groove and the magnet will produce the trough effect, and the no core DC electric opportunity to eliminate this effect, so the trough effect and torque lag will not exist;

5) Low starting torque: with no hysteresis loss and slot effect, the starting torque is very low, usually the bearing load is the only obstacle; the rotor and stator are small, so their magnetic field is relatively weak. And because of the hollow design, the gas inside the motor is low, so the flow of air will also weaken the magnetic field, thus affecting the starting torque of the motor.

6) There is no radial force between the rotor and the stator of the micromotor: the DC motor without the core rotor, and there is no radial magnetic force between the rotor and the stator. In some applications, the radial force between the rotor and the stator will cause the rotor instability, so reducing the radial force can improve the rotor stability;

7) Slide speed curve, low noise: no core rotor reduces the harmonic of torque and voltage. Because there is no AC field in the micromotor, so there is no noise generated by AC, only the noise generated by bearings and airflow and the vibration generated by non-sinusoidal current;

8) High-speed coil: when the micromotor runs at high speed, the inductor value parameter is very important, and the small inductance value will make the start voltage low. The inductance meter reduces the weight of the micromotors and increases the shell thickness by increasing the number of poles and reducing the power density.

9) Fast response: due to the low induction value of micromotor, the current response to voltage fluctuation, the inertia of the rotor is small, the response speed of torque and current is similar, so the acceleration of the rotor is about twice that of ordinary core motor;

10) High peak torque: The ratio of peak torque to continuous torque of the micro motor is large, because the torque constant is constant when the current rises to the peak, and the linear relationship between the current and torque can enable the micromotor to produce greater peak torque. After the ordinary core DC motor reaches saturation, no matter how much the current increases, the torque of DC motor increases.

11) Good heat dissipation: air flow on the surface of the rotor, better than the core rotor. The enameled wire of the iron core rotor is embedded in the groove of the silicon steel sheet, and the air flow on the surface of the coil is less, and the temperature rise is higher. Under the same power output conditions, the temperature rise of the DC motor is low.

Shortcoming

When the coreless micromotor is in a stationary state, such as the phase disconnection of the winding or the phase connection of the power supply, the two magnetic fields produced in the opposite direction, they have the opposite direction to the torque produced by the rotor, so that the motor can not start under the zero starting torque, which is the disadvantage of the micromotor.

The above are some professional knowledges on the coreless DC motor by VSD Motors. For more relevant information, please contact us.