Permanent magnet motor is a kind of motor that uses permanent magnet to establish magnetic field. It is also a common motor. After being made, permanent magnet motor can maintain its magnetic field without external energy. So what are the magnetization requirements and design methods of permanent magnet motor? Let's learn together!
The design method is as follows:
1. Magnetic circuit method: the uneven alternating magnetic field in the permanent magnet motor can be equivalent to the corresponding magnetic circuit, so that the magnetic field accounting can be transformed into the magnetic circuit accounting. Because there are many correction coefficients used in the calculation of equivalent magnetic circuit, the accurate value cannot be calculated theoretically. Generally, empirical data are used. If the scheme designed at the beginning does not meet the original design requirements, it is necessary for the designer to select the correction value from the beginning and calculate again.
2. Finite element method: in order to make the calculation accurate, it is necessary to analyze the electromagnetic field, such as the shape and size of permanent magnet poles, partial demagnetization, etc. The finite element software is used to calculate and analyze the electromagnetic field, which saves the development cost of the product, and provides an accurate basis for the optimal design of the motor. The improvement of the function of the accounting machine enables various analytical methods of the electromagnetic field numerical accounting theory to be carried out. The essence of finite element method is to transform the problem into a structural problem suitable for numerical solution. It idealizes the continuous system of infinite degrees of freedom into a set of finite multi degree of freedom elements. Now, Ansoft is the most commonly used finite element simulation software, which can jointly simulate the whole motor system.
3. Field circuit combination method: Although the magnetic circuit method has fast accounting speed, its accuracy is not high, and the accounting machine has high accounting accuracy, but the accounting is slow and has high requirements for the accounting machine. Therefore, the combination of the finite element method and the traditional magnetic circuit method can not only improve the calculation power, but also improve the accuracy. This is of great practical value to the design of motor parameters. The basic idea of the field circuit combination method is to first refer to the magnetic circuit calculation results, start to establish a geometric model, and then analyze the magnetic field through the finite element method to accurately calculate the coefficients that need to be corrected in the equivalent magnetic circuit method.
Magnetization requirements are as follows:
In the permanent magnet motor, the commutator is equipped with an electric brush, which can convert the external DC power supply into the alternating current in the armature coil, so that the direction of the electromagnetic torque is stable. It is the most widely used motor now. Let's understand its magnetization requirements.
Different uses of permanent magnet motors require different functions. Different functions depend on the internal electromagnetic structure parameters of the motor. In terms of magnetic parameters, different air gap magnetic field dispersion shapes are required. For example, for permanent magnet DC motors driven by pure output, their functions require higher output power and power. Therefore, the internal air gap magnetic field dispersion of such motors should select flat top waves equal to or slightly greater than 2/3 pole distance, So as to supply as much magnetic flux as possible, so that the motor has a large electromagnetic torque. For example, for permanent magnet DC motors with small oscillation, low noise and small spark, but with low requirements for output power and power, the internal air gap magnetic field dispersion shall be flat top wave or sine wave with less than 1/3 pole distance to ensure the applicability of such motors. In order to obtain the air gap magnetic field waveform with different dispersion shapes, it is not only related to the reasonable design of the magnet structure shape and the selection of the magnetic orientation of the magnet, but also related to the magnetization method of the magnet, that is, the design of magnetization technology.
The magnetization requirements of this equipment have been explained clearly in the text. The structure of permanent magnet motor will be more complex, the accounting structure will be more accurate, and the manufacturing process will be more advanced and applicable. These complex problems require the use of multidisciplinary theory and system engineering to optimize design, improve cost performance, and promote the further development of disciplines and professions such as motors.
