A motor design basis

Motors are generally designed based on the following technical requirements:

The type or purpose of the motor. The motor generator special purpose motor.

The electrical system connected to it requires a motor current frequency, frequency, etc.

The electrical machinery system and working environment connected to it require the motor geometry, quality structure and installation type, protection type, cooling mode, flyaway speed or overspeed rotational inertia, etc.

Rated data, operating modes and various performance requirements for different uses Power speed Working efficiency Power factor Starting performance Commutation performance Excitation performance Voltage change rate Voltage waveform variability Vibration and noise limits and motor limits for radio interference etc. .

The ability of the motor and its components to withstand the thermal loads of the electrical machinery, such as the insulation level of the windings and the dielectric strength of the windings, the dielectric strength of the windings, and the mechanical strength of the rotor.

The national standard professional standards design task book and other requirements put forward by users.

In addition, the possibility of production and the economic rationality should also be considered.

The basic content of the two motor design

Motor design generally includes two parts: electromagnetic design and structural design. Electromagnetic design is to determine the size and winding data of the effective part related to the electromagnetic load and electromagnetic performance of the motor according to design technical requirements, select materials, and calculate the electromagnetic performance and related parameters. The motor design generally requires analysis and comparison of various schemes, or adopts an optimization design method, and considers factors such as operating cost of the motor performance, manufacturing cost, operating reliability, etc., to determine the optimal design. For a large amount of production, use a wide range of motors, generally into a series of design and manufacturing, design should fully consider the standardization of the generalization of the requirements of the series, for many varieties of small batch production of motor products, should pay attention to modular design.

Three motor design standard value

In order to facilitate the calculation and comparison of different design schemes or operating conditions, motor parameters are often used to designate the motor parameters. The parameter value of the motor parameters is the ratio of the actual value expressed in physical units to the selected reference value. The selection of the reference value is arbitrary, and the reference values ​​of the parameters usually used are shown in the table.

Four Computers in Motor Design

Because of its prominent fast calculation function storage function and logic judgment function, the computer has been widely used in the motor design, and the traditional motor design method has undergone profound changes. As an electromagnetic design program that is the basis of motor design, after the computer has replaced complex manual calculations, a more practical mathematical model can be used to improve the existing design calculation formula, thereby improving the accuracy of product design. For example, the equivalent circuit of an asynchronous motor is originally an equivalent circuit. In the past, in order to meet the needs of manual calculations, it was simplified into a shape equivalent circuit. After using a computer, the circuit can be easily used, and the calculation accuracy can be improved. If you consider the role of higher harmonics, using a chain equivalent circuit, the design calculation will be more accurate. In addition, due to the use of a computer, more complex mathematical models can be solved numerically, so that in the past, items that can only be roughly estimated or cannot be calculated, such as steady-state and transient thermal calculation transient phenomena, are studied for the criticality of mechanical strength and bearing carrying capacity. The calculation of many items such as the rotational speed and the natural frequency of the iron core becomes possible. These projects are being incorporated into the motor design process, so that the motor design calculations are based on a more reliable science. The end result of the motor design is to create drawings and related documents for manufacturing. Due to the rapid development of computer graphics technology, such as light pen graphics display allows designers to carry out specific structural design drawings on the screen or digitizer, and may be modified in real time through human-machine dialogue; again, such as a sophisticated automatic plotter can be The design results are directly output in the form of drawings, so that the motor design from the electromagnetic design to the structural design, and the entire process including drawing the pattern can be completed with the aid of a computer. Computer-aided design can significantly improve the efficiency and accuracy of motor design, shorten the product development cycle, and generate standard drawings and documents. Therefore, this approach is gradually replacing traditional design methods characterized by empirical design and manual drawing. In addition, when a computer aided design system is combined with a computer aided manufacturing system, the design and manufacturing process of the motor product can be turned into a complete integrated system, which will automate many technical tasks. Therefore, it will be the calculation of the motor manufacturer. Integration provides the technical foundation.

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