1, hollow cup motor: the body is “small”, the performance is “strong”, is the “crown pearl” in the field of motor

(A) Hollow cup motor: the core components of humanoid robot dexterous hands

Dexterous hand is the final part of humanoid robot, which is very important and complex, and requires high performance of motor. Smart hand as a robot to achieve the operation of the terminal tool, very important, its design is highly imitation of the human hand, the structure is more complex, the biggest problem facing is the space is very small and the driving degree of freedom is very much, need to be equipped with high power density, small volume and high control precision motor. The hollow cup motor is highly compatible with the dexterous hand joint and is used as a power source in the Tesla Optimus. The hollow cup motor has the characteristics of high power density, high energy conversion efficiency, fast response, smooth operation and so on, which is highly suitable for the needs of dexterous hands. Tesla robot “dexterous hand” uses a more classic six-motor drive, and the same as the human hand uses 5 fingers, with 11 degrees of freedom, the thumb uses a double motor to drive bending and side swing, and the other four fingers are driven by a motor. The purpose of using worm drive mechanism in motor is the same as that of leg linear servo, using mechanism self-locking to reduce energy consumption. In order to pursue beautiful shape and adaptability, the finger adopts a pulling wire transmission mechanism, with a load of 20 pounds (9KG) and adaptive grasp (can grasp objects of different shapes and sizes), can complete the handling, watering and other actions.

(2) Structure and performance: the coreless rotor structure breaks the routine, and the motor performance is improved in all aspects.

There are many kinds of motors, and hollow cup motors have attracted much attention due to their performance advantages. Since the invention of the motor has gradually entered all aspects of our lives, it is one of the most widely used electrical equipment in daily life. The motor can be divided into DC motor using DC power supply and AC motor using AC power supply according to the type of working power supply, and can be divided into drive motor and control motor according to the use of classification, which can be divided into open-loop control stepper motor and servo motor can achieve accurate closed-loop control. Hollow cup motor is a kind of micro servo motor using permanent magnet to provide magnetic field, DC power supply, with the continuous progress of industrial technology, mechanical and electrical equipment to better adapt to various needs of the servo motor technical requirements are getting higher and higher, and hollow cup motor is also due to its good energy saving effect, good servo characteristics and other performance advantages and attention.

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The hollow cup motor body is “small”, the performance is “strong”, and it is the “crown pearl” in the field of motor. From the structural point of view, taking the brushed hollow cup motor as an example, it is mainly composed of hollow cup winding, permanent magnet, brush, commutator and other components, using a no-core rotor structure, the components are tightly combined, usually the size is relatively small, the diameter does not exceed 40mm. From the performance point of view, the rotor structure without iron core has greatly improved the performance of the motor, so that it has excellent energy saving, high efficiency, high sensitivity, stable operation and other characteristics.

Hollow cup motor VS traditional DC motor: The coreless rotor structure breaks the routine, and the motor performance is improved in all aspects. The hollow cup motor uses a coreless hollow cup winding, which is the core difference from the traditional DC motor. The winding is the main part of the motor. The induced electromotive force in the winding and the electromagnetic torque generated by the current in the winding realize the conversion of electromechanical energy and the transmission of electromagnetic power. The rotor of the traditional DC motor is composed of iron core and winding, while the winding of the hollow cup motor is composed of wire wound into a cup, and the difference in structure makes the performance of the two are very different.

The unique hollow cup coil structure greatly improves the motor performance. This new structure reduces the magnetic resistance moment of the motor during operation and reduces the output torque fluctuation because there is no punching tooth groove structure and iron core. The hollow cup motor fundamentally eliminates the loss caused by the eddy current effect of the iron core, thereby reducing the energy loss during the operation of the motor, while reducing the weight of the motor, and the performance has been greatly improved. Compared with the traditional DC motor, the hollow cup motor has the characteristics of high power density, high energy conversion efficiency, fast response and smooth operation.

(1) No iron loss and light weight make hollow cup motor energy conversion efficiency is high, energy saving effect is good. No iron loss: Iron loss refers to the iron core in the permanent magnet DC motor. Because the magnet is affected by the changing magnetic field, part of the energy lost in the micromotor core will be lost in the way of heat or in the way of noise. It mainly includes eddy current loss induced by internal magnetic field changes, hysteresis loss caused by domain expansion and contraction, and abnormal loss (loss other than eddy current loss and hysteresis loss). The hollow cup motor adopts a coreless structure, which almost completely eliminates the energy loss caused by eddy current effect and hysteresis effect. At the same time, because of this, the hollow cup motor has a higher energy conversion efficiency than the traditional DC motor. Light weight: the moment of inertia and weight of the hollow cup motor are significantly lower than that of the ordinary motor, so the mechanical energy loss of the converter itself will be reduced during the operation of the motor.

According to the statistics of the new motor, the efficiency of the hollow cup electric energy conversion machine is generally more than 70%, and some products can reach more than 90%, while the energy conversion efficiency of the ordinary iron core motor can only reach 15%-50%.