The advantages of adjustable angle phase-shifting and great expansibility make the linear phase-shifting transformer a novel type of power conversion device with a wide range of potential applications. However, during the procedure, there is a lot of noise. For the purposes of transformer design and vibration and noise reduction, it is crucial to investigate its electromagnetic vibration and noise. In this paper, the radial electromagnetic force wave considering the influence of the end effect as the source of the noise of the linear phase-shifting transformer was deduced and calculated. Based on this, the spectrum and space–time properties of the radial electromagnetic force waves were simulated and verified. Additionally, a finite element model was created using the Ansys Workbench 2022R1 platform to study the electromagnetic vibration and noise of the linear phase-shifting transformer. A joint simulation of the electromagnetic, structural, and sound fields was then performed. First, the transformer’s natural frequency was determined by modal analysis. After that, the transformer’s structure and the results of the transient electromagnetic field computation were combined and a harmonic response analysis was conducted to determine the vibration acceleration spectrum. Finally, in order to solve the sound pressure field, the transformer’s boundary vibration acceleration was coupled to the air domain. Furthermore, an analysis was conducted to determine the noise distribution surrounding the linear phase-shifting transformer. The joint simulation findings demonstrate that the linear phase-shifting transformer’s resonance, which produces larger electromagnetic vibration and noise, is indeed caused by the radial electromagnetic force. Simultaneously, the impact of the LPST core’s fixed components on the electromagnetic vibration and noise of the core was examined.
Linear induction motors (LIMs) have been widely used in rail transit. However, Due to the breaking of the primary core and the large air gap, the efficiency and power factor of LIMs are seriously damaged, causing a large amount of energy waste. To improve the efficiency and power factor of LIMs for urban rail transit, we present a new optimization method for the design of a short primary double-sided linear induction motor (SP-DLIM) with a rated speed of 45 km/h and small thrust. The method is based on a steady state equivalent circuit model and the differential evolutionary algorithm (DEA). Moreover, the design constraints and the objective functions are proposed for the optimization problem. Finally, the optimized SP-DLIM is simulated by 2D transient finite element method (FEM). The 2-D transient FEM results verify the accuracy of the optimization method proposed in this paper.
For a new type of toroidal permanent magnet linear motor(TPMLSM), this paper analyzes the thrust fluctuation in the constant acceleration operation of the motor from the Angle of the cogging force of the linear motor. For the motor whose structure has been determined and processed, the structural parameters of the motor cannot be changed, and its performance cannot be improved from the perspective of the motor body. Therefore, this paper tries to consider the influence of the cogging force on the normal operation of the motor from the perspective of control. In this paper, starting from the body structure of motor, first on the annular linear motor of the cogging force characteristics were extracted, and its expression is obtained by Fourier decomposition, then investigated considering the cogging force and does not consider the cogging force control of motor model, it can be seen that the control performance deteriorates significantly after considering cogging force of the motor, and the acceleration fluctuation increases significantly during the operation of the motor. On this basis, disturbance observation algorithm is introduced, and feedforward compensation is carried out by extracting the characteristic values of the disturbance model. The results show that the disturbance observer can suppress the thrust fluctuation caused by the motor cogging force to a large extent, and it can reduce the peak-to-peak value of the thrust fluctuation by more than 85% during the motor acceleration operation.
Compared with the traditional induction motors, five-phase squirrel cage induction motor (FSCIM) have the advantages of lower torque ripple and single-phase power, flexible control strategy, higher power density and fault-tolerant operation, which has been widely applied on electrical vehicles, rail transit, underwater vehicles and so on. This paper presents an analytical design optimization method based on the coupling of electromagnetic equivalent circuit (EEC) and differential evolution algorithm (DEA). Furthermore, the difference between three and five-phase winding on harmonic specific leakage permeance is investigated in detail. The nonlinear and oeolotropic influences of design geometrical parameters (slots openings, main dimension ratio, yoke height, airgap length, etc.) on the performances of the basic FSCIM model are evaluated with analytical model. For more accurate results, the harmonic characteristics of five-phase winding structure, iron core saturation, rotor slot skew width, stator end winding, slot leakage inductance and stator and rotor slot structure are considered. Meanwhile, the efficiency, power factor, maximum torque, slot fill factor and material consumption of FSCIM are calculated as the comprehensive objective function. The transient finite element analysis (TFEA) and experimental test verify the accuracy of the proposed optimum model. In addition, the feasibility of the multi objective optimization design scheme provided by the analytical model is verified by TFEA.
Abstract In order to solve the H-bridge DC converter under the traditional pulse width modulation the peak value of EMI is mainly distributed at the switching multiple frequency, and the serious electromagnetic interference. This paper introduces dual pulse width modulation harmonic suppression technology based on the H-bridge DC converter. By expanding the spectral distribution of the harmonics by two pulse widths, the duty cycle and phase of the two pulse widths can be changed to reduce the power of a certain harmonic, and compared with the traditional single pulse width, the analysis of the two pulse width modulation Spectrum distribution on the grid side. The electromagnetic interference under two kinds of pulse width modulation is realized by analyzing through matlab / Simulink software simulation.
The position servo system with the vector control for the PMLSM is built in this paper.The harmonic analysis between the two different methods in forming a vector in SVPWM are compared.The software and the drive circuits of IR2130 of the control part are given.The experiment with comments show well result.
In the vector control of three-phase motor,current feedbacks are normally directly measured by CTs(Current Transformers),which needs at least two isolated CTs.To measure three feedback currents indirectly with a resistor and a DSP(Digital Signal Processor)-based real-time controller is proposed.However,when the PWM(Pulse Width Modulation) frequency is too high in SVPWM(Space Vector PWM),the measurement becomes more difficult and even impossible due to hardware limitations.Lengthening method,which lengthens PWM period to avoid hardware limitations,is proposed,but the lowered PWM frequency may result in poor stator flux control.Compensation method,which compensates the time gap between transistor commutations for current sampling in one PWM period without varying the PWM period,is also proposed.Its flowchart and current sampling circuit are offered.Test on a 400 W asynchronous motor shows that the compensation method is more efficient and extensive.
The linear phase-shifting transformers (LPSTs) are a new type of transformers with a structure similar to a linear motor that can be used in multiplex technology. A reasonable equivalent circuit is the premise of control research. Based on one-dimensional electromagnetic field analysis of the LPST, we reference the theory of linear motor and propose an equivalent circuit model of the LPST. The LPSTs, which are a phase-shifting transformers based on linear motor structure, are affected by end effects. The end effects affect the mutual inductance and secondary resistance of the LPST, which is modified by four correction coefficients. This paper calculates the four correction coefficients, inductance, and resistance of the LPST and then proposes a single-phase T-type equivalent circuit model considering end effects. Using the analytical model, the output voltages under the three working conditions are calculated and analyzed, and the accuracy is verified by comparison with results obtained by the finite element method. Finally, the accuracy of the analytical method is further verified by experiments under two working conditions, which indicates that the equivalent model is credible and useful for control research of multi-inverter system based on the LPST.
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