CN105720709B - Stator structure of compact permanent magnet brushless motor - Google Patents

Abstract

The invention discloses a stator structure of a compact permanent magnet brushless motor, belongs to the field of motors, and aims to solve the problem that the performance of the motor is reduced due to the fact that a Hall element is directly embedded into a stator slot of the existing stator structure and the positioning torque of the motor fluctuates. The stator structure comprises a stator core and a plurality of stator teeth, wherein the inner circular surface of the stator core is uniformly provided with the plurality of stator teeth, and the inner circular surfaces of all the stator teeth are positioned on the same circumference; a stator slot is formed between every two stator teeth, three Hall elements are embedded in the stator slot in a three-phase symmetrical mode, two stator teeth of the stator slot where each Hall element is located are two special teeth which are arranged in a mirror symmetry mode, and stator teeth at other positions are normal stator teeth; the pole shoe of the special tooth facing one side of the Hall element is nearly absent, and the thickness ht2 of the pole shoe of the special tooth facing away from one side of the Hall element is far larger than the thickness ht1 of the pole shoe of the normal stator tooth.

Description

Stator structure of a compact permanent magnet brushless motor

technical field

The invention relates to a special groove structure design of a high power density segmented permanent magnet brushless motor for a mechanical arm, and belongs to the technical field of motors.

Background technique

The space robotic arm is an important device necessary for space engineering, assisting astronauts to complete high-precision transportation and maintenance work. The design requirements of the mechanical arm are high strength, high reliability, flexible work and light volume and weight as possible. Electromagnetic devices are essential in the manipulator drive system. Compared with hydraulic drive and other common drive methods for ground manipulators, electromagnetic drive has great advantages in the space field. Therefore, as far as the current development of the space field is concerned, other countries with advanced space science and technology have adopted electromagnetic drive methods to solve the drive problem of space manipulators.

As an important core equipment of electromagnetic drive, the motor has many technical difficulties in design and processing. Among them, the corresponding schemes are analyzed and compared for high reliability, high efficiency, high controllability, and weight reduction. Since the motor is mainly composed of magnetically permeable ferromagnetic materials and conductive electromagnetic materials, its weight reduction can only be reflected in increasing energy density, so permanent magnet motors are the ideal solution. At the same time, the method of appropriately increasing the motor speed to reduce the volume of the motor is adopted, and at the same time, it is equipped with an appropriate reduction device to achieve a comprehensive design that minimizes the size and weight.

At present, the country is vigorously developing the Industry 4.0 plan, and has also proposed specific development goals for the robot industry. Space manipulator technology can be applied to ordinary civilian fields and drive the development of the robot industry.

While reducing the weight and volume, it is required to take into account the reliability, cost and cost of the motor.

In order to increase the power density, reduce the size of the motor, and minimize the impact on the performance of the motor, it is necessary to embed the Hall element as a position sensor in the groove. This method has superior motor performance than embedding in teeth. However, directly embedding the Hall element in the stator slot of the existing stator structure will cause fluctuations in the positioning torque of the motor, resulting in a decrease in the performance of the motor.

Contents of the invention

The purpose of the present invention is to solve the problem that directly embedding the Hall element in the stator slot of the existing stator structure will cause fluctuations in the positioning torque of the motor, resulting in a decrease in the performance of the motor, and provides a stator structure for a compact permanent magnet brushless motor .

A stator structure of a compact permanent magnet brushless motor according to the present invention, the stator structure includes a stator core and a plurality of stator teeth, a plurality of stator teeth are uniformly arranged on the inner circular surface of the stator core, and the inner circular surfaces of all the stator teeth are located at On the same circumference; a stator slot is formed between every two stator teeth, and a Hall element is embedded in the corresponding three stator slots in a three-phase symmetrical manner, and the two stators of the stator slot where each Hall element is located The teeth are two special teeth set in mirror image symmetry, and the stator teeth in other positions are normal stator teeth; the pole shoe on the side of the special tooth facing the Hall element has a raised structure, and the special tooth is away from the pole shoe on the side of the Hall element The thickness ht2 is much larger than the pole shoe thickness ht1 of normal stator teeth.

The advantage of the present invention is that the patent of the present invention adopts a special cogging design scheme to ensure that the impact on the positioning torque and torque fluctuation of the motor is minimized while the Hall element is embedded.

The stator structure involved in the present invention is applied to a low-inertia permanent-magnet brushless torque motor. It is used as a driving device for a space or civil mechanical arm joint, and can directly meet the requirements for low-speed operation at the end of the mechanical arm. Compared with the prior art that uses high-speed The motor is matched with the gear reduction device to meet the requirements of use, so that the structure is simple and the complex procedures of the motor system are reduced; at the same time, because the rotor adopts a hollow disc type, it can achieve the maximum torque output under the premise of the same weight, which is more suitable for the aerospace field . However, using the method of embedding Hall devices reduces the overall length of the motor, which is of great benefit to reducing weight and increasing power density.

Description of drawings

Fig. 1 is the structural representation of the stator structure of a kind of compact permanent magnet brushless motor of the present invention;

Figure 2 is a schematic diagram of the comparative structure of two tooth shapes in the stator structure.

detailed description

Specific Embodiment 1: The present embodiment will be described below in conjunction with FIG. 1 and FIG. 2. The stator structure of a compact permanent magnet brushless motor described in this embodiment includes a stator core and a plurality of stator teeth. A plurality of stator teeth are evenly arranged on the inner surface of the stator, and the inner surface of all the stator teeth is located on the same circumference; a stator slot is formed between every two stator teeth, and is buried in the corresponding three stator slots in a three-phase symmetrical manner. Insert a Hall element 3, the two stator teeth of the stator slot where each Hall element 3 is located are two special teeth 2 that are mirror-symmetrically arranged, and the stator teeth in other positions are normal stator teeth 1; the special teeth 2 face the Hall The pole shoe on the side of the Hall element 3 has a convex structure, and the thickness ht2 of the pole shoe on the side of the special tooth 2 facing away from the Hall element 3 is much larger than the thickness ht1 of the pole shoe of the normal stator tooth 1 .

In order to solve the problem that the existing space manipulator is driven by a high-speed motor and needs to be equipped with a gear reduction device, which makes the structure of the motor system complex. The motor involved in this embodiment is a motor with as small a volume as possible. In order to reduce the axial volume of the motor, the method of embedding the Hall element 3 in the motor slot is adopted.

Place the Hall element 3 on the inner circle of the stator, on the center line of the stator slot. The three-phase Hall elements should be placed symmetrically. The corresponding phase relationship between the Hall element 3 and the back EMF of the phase winding should maintain three-phase symmetry.

This embodiment includes a special stator tooth shape of the brushless permanent magnet motor suitable for accommodating Hall elements. Tooth shapes are divided into two categories. They are normal tooth shape (normal stator tooth 1) and abnormal tooth shape (special tooth 2). It can be seen from the figure that one side of the abnormal tooth shoulder is almost missing because of the need to place the Hall element 3 .

Specific implementation mode 2: This implementation mode further explains the implementation mode 1, and this implementation mode provides a specific example of parameter matching ht2=2.5ht1. But not limited to this example.

ht1 should be significantly smaller than ht2, the purpose is to make the magnetic density distribution of the air gap where the special tooth 2 is located very close to the air gap magnetic density distribution of the normal stator tooth 1, and the tooth shoulder will not be too saturated, so as to achieve a uniform distribution of the air gap magnetic density The purpose is to minimize the cogging torque and torque fluctuation.

Claims (2)

1. The stator structure of a compact permanent magnet brushless motor is characterized in that the stator structure comprises a stator core and a plurality of stator teeth, and a plurality of stator teeth are evenly arranged on the inner circle surface of the stator iron core, and the inner circle of all stator teeth The surfaces are located on the same circumference; a stator slot is formed between every two stator teeth, and a Hall element (3) is buried in the corresponding three stator slots in a three-phase symmetrical manner, and each Hall element (3 ) where the two stator teeth of the stator slot are two special teeth (2) arranged symmetrically in mirror images, and the stator teeth in other positions are normal stator teeth (1); the special teeth (2) face the Hall element (3) The pole piece on the side has a convex structure, and the pole piece thickness ht2 on the side of the special tooth (2) facing away from the Hall element (3) is much greater than the pole piece thickness ht1 of the normal stator tooth (1). 2. The stator structure of a compact permanent magnet brushless motor according to claim 1, wherein ht2=2.5ht1.