Search Results (3)

Induction motors have a simple structure, have low manufacturing costs and are widely used. However, various vibration effects with mechanical or electromagnetic origins are also very common. To analyze the impact of rotor skewing on electromagnetic vibrations in induction motors, this paper investigated the skew factor of skewed rotor slots and proposes an electromagnetic force wave analysis method. The method aimed to optimize the skew angle parameters for vibration amplitude reduction, with its effectiveness verified through simulations and experiments. Taking a 7.5 kW four-pole induction motor with 36 stator slots and 28 rotor slots as the research object, the suppression law of different skew parameters on force waves generated by stator harmonics was obtained. Results show that when the rotor is skewed by an angle equivalent to three stator teeth pitch, electromagnetic forces of different orders are attenuated by approximately 5% on average. Physical rotors with skew angles of 0°, 10°, 12.8°, 14°, and 20° were manufactured for experimental validation, while considering the influence of rotor skewing on starting torque and maximum torque. The study concludes that the amplitude of tooth harmonics varies with the skew coefficient, consistent with the skew factor analysis. By analyzing motor vibration with the skew coefficient, the amplitude relationship of electromagnetic vibration under different optimization parameters can be determined, thereby selecting reasonable skew parameters for rotor optimization. Full article

A skid-to-turn (STT) missile is an axisymmetric structure missile, and its control system consists of a pitch channel and a yaw channel with an axisymmetric structure. To achieve the fast response of the STT missile system, a compound control method of aerodynamic force and lateral thrust based on regional pole assignment (RPA) is proposed. In the aerodynamic control system, the linear quadratic regulator (LQR) is used to design the controller, and the sliding mode control method is used to design the controller of the lateral thrust system. The regional pole assignment is introduced into the aerodynamic system to improve the compound control system response speed. The problems of regional pole assignment and system stability are solved by a linear matrix inequality (LMI). Considering that the missile flies at different altitudes, the missile system is controlled by gain scheduling. Compared to previous designs of time-varying compound control systems for STT missiles or hypersonic vehicles, in order to meet the practical requirement of a fast response for the vehicle, this time-varying compound control strategy can achieve faster tracking response and attitude control for the STT missile. Finally, through simulations of the pitch channel and yaw channel control systems of the STT missile, the effectiveness of the designed compound control system in achieving a fast response is verified. Full article

According to the special technical requirements of carrier-based aircraft catapults, this paper describes the design of a variable pole distance bilateral linear induction motor. When the traditional constant pole motor is used as the catapult of carrier-based aircraft, the current frequency continues to increase during the catapult process, which greatly aggravates the burden of the motor. Therefore, we propose a variable pole length primary double-sided linear induction motor structure. Compared with the traditional constant pole motor structure, this structure can gradually increase the pole distance with an increase in speed when the current frequency remains unchanged. In contrast, the variable pole distance method with a current frequency of 200 Hz has a pole distance of 0.262 m when the displacement is 10 m, and the pole distance increases to 0.352 m when the displacement is 100 m. By maintaining a constant current frequency, this method effectively reduces the control complexity at high speed. Through the theoretical analysis and research calculation conducted on the designed motor, a finite element simulation model was also established by ANSYS 14.0, and the influence of the change in the pole distance on the performance of the motor was analyzed. The magnetic field line and magnetic density distribution of the motor are simulated and analyzed, and the validity of the theoretical calculation is verified. Full article