Synchronous homopolar motors (SHMs) have been attracting the attention of researchers for many decades. Various mathematical models of SHM have been proposed to deal with its complicated magnetic circuit. Among them, there are time-consuming 3D finite element models (FEM), equivalent circuit models neglecting some significant features of the machine design, and 2D FEM models with virtual excitation winding distorting its magnetic field picture. This paper proposes a novel 2D FEM of SHM and shows that since there are no sources of excitation in the cross-sections of the rotor and stator stacks, no virtual elements are required. This model uses the general solution of the Gauss’s law for magnetism containing excitation flux. The model is based on a set of magnetostatic boundary value problems for various rotor positions. The set of boundary problems is completed with the excitation equivalent circuit. The losses in the armature and field windings and the stator and rotor magnetic cores are computed in postprocessing. All these computations are carried out for a single combination of stator and rotor stack. A symmetrization algorithm is proposed to extend the obtained results to the whole SHM. A comparison of the theoretical and experimental data for a nine-phase three-section 320 kW SHM is carried out. These SHMs were used in a mining truck with a carrying capacity of 90 tons.

Traction Synchronous Homopolar Motor: Simplified Computation Technique and Experimental Validation

https://onlinelibrary.wiley.com/doi/pdf/10.1049/pel2.12002

Study of capacitor charge power supply with homopolar inductor alternator: System modelling and mode analysis

Effect of crystallization temperature on energy-storage density and efficiency of lead-free Bi0.5(Na0.8K0.2)0.5TiO3 thin films prepared by sol–gel method

For improving the power density of a homopolar inductor alternator (HIA) in a capacitor charge power supply (CCPS), a novel excitation compensation (EC) method is proposed in this article, wherein a compensation winding is installed in the HIA for providing pulse excitation and increasing the charge power. First, high-power and high-energy density requirements of the CCPS in the pulsed power supply (PPS) are presented, and the power density problem of the HIA caused by its homopolar structure is discussed. Second, methods for improving the charge power in the CCPS are studied, and a good way is to provide strong excitation to increase the machine electromotive force (EMF) during the charge process, whose difficulties are also studied. Third, a novel excitation-compensated HIA (ECHIA) is introduced and the principle and the effect of different EC circuits are analyzed. In the end, simulation results of the same size ECHIA and a conventional HIA show that the novel EC method can indeed improve the charge power in the CCPS and help the HIA achieve higher power density.

Analysis of a Novel Excitation Compensated Homopolar Inductor Alternator Used for Capacitor Charge Power Supply

The air-core pulsed alternator capable of miniaturization and lightweight has become one of the most potential power supplies for electromagnetic railguns equipped in all-electric vehicles or ships that have strict restrictions on volume and weight. Although the air-core machine has undergone decades of continuous research, a systematic theoretical basis is still in absence, especially for electromagnetic analysis and transient operating analysis. Besides, researchers are less willing to share their latest achievements for the sake of national interests, and the detailed experimental results of this alternator are seldom made public in recent years. In this article, the electromagnetic theoretical analysis, including the analytical expressions of magnetic flux density and inductance parameters, is carried out. Then, a comprehensive transient operating theoretical analysis of four stages is put forward with some typical operating parameters derived. Based on these two kinds of theoretical analysis, the scheme of a six-pole and seven-phase alternator is determined. Simulations are executed to verify the theoretical analysis and prove that the designed alternator can meet the proposed operating targets. Finally, some preliminary experiments for the fabricated prototype are conducted under low experimental parameters. The experimental results indicate that the power electronic devices can work properly, and the self-excitation rectifier takes effect in lifting up the field current. Although the discharge experiment is not carried out under rated experimental parameters, it still makes sense since it reveals the superiority of the prototype in releasing a discharge current very close to an ideal trapezoidal wave to ensure that the projectile can move steadily in its acceleration process.

Analysis and Preliminary Experimental Research of a Multiphase Air-Core Pulsed Alternator

In order to realize quick preliminary design for capacitor charge power supply (CCPS), a novel critical analysis method of homopolar inductor alternator (HIA) is proposed in this paper. First, a specific base value system of CCPS is proposed for making the critical analysis method universally applied for different machine and charge parameters. Second, under the equivalent average-value phase model of HIA, a critical curve and a maximum power analysis method based on the curve are proposed. After that, an outline of the preliminary machine design under the critical analysis method is presented. Third, considering the salient rotor structure of HIA, under the equivalent average-value direct- and quadrature-axis (DQ) model of HIA, a critical map as well as its maximum power analysis method is proposed. In the end, for these two types of critical analysis method under different average-value models, each of their advantages and applications are discussed.

A Novel Critical Analysis Method of Homopolar Inductor Alternator for Preliminary Design in Capacitor Charge Power Supply

As the most efficient and compact sources in pulsed power supply for electromagnetic launchers, the air-core pulsed alternator can supply a current as high as 1 MA with a voltage reached several kilovolts. The machine performs various functions, such as kinetic energy storage, electromechanical energy conversion, and power conditioning, making the electromagnetic launch system compact and lightweight. But due to the short history of the machine and the absence of fabrication experience in China, the air-core pulsed alternator is still in an exploratory stage, and there are lots of key technologies and problems needed to be researched deeply. Taking technical risks and manufacturing costs into consideration, a seven-phase air-core pulsed alternator has been proposed and the machine is under development. In this paper, operation principles of the electromagnetic launch system are presented in detail. The mathematical models of the seven-phase alternator and the rail gun are introduced. Based on the mathematical models, a simulation model about the electromagnetic launchers is built, and it is useful to help us figure out the operation characteristic when the self-excitation machine drives the electromagnetic rail gun with a 200-g projectile. As a result, it is convincing by simulation to prove the drive current can be as high as 1 MA and the projectile is with a velocity of 2 km/s at the exit. Simultaneously, violent transient situations will be illustrated in this text, such as the electromagnetic torque and the rotor speed. Meanwhile, simulation results can verify the analytical method and present the current and voltage straightforwardly. They also have great significance on choosing the proper high power switching devices.

Simulation of a Seven-Phase Air-Core Pulsed Alternator Driving the Electromagnetic Rail Gun

Brushless doubly-fed alternator (BDFA) has good application prospects in pulsed alternator It works through the rotor’s pole pairs transformation function to get excitation indirectly Since there are no brush and slip ring, BDFA is expected to have high reliability and long service life This paper studies on the excitation control of BDFA in pulse capacitor charge power supply system A mathematic model of BDFA is established The power angle characteristic of BDFA and flux changing condition during discharging process is analyzed with this model Based on the analysis, a novel excitation control theory is proposed Simulation results are presented to illustrate the performance of this control strategy

Jiakang Yao

Papers

A Novel Critical Analysis Method of Homopolar Inductor Alternator for Preliminary Design in Capacitor Charge Power Supply

Study of capacitor charge power supply with homopolar inductor alternator: System modelling and mode analysis

Simulation of a Seven-Phase Air-Core Pulsed Alternator Driving the Electromagnetic Rail Gun

Analysis of a Novel Excitation Compensated Homopolar Inductor Alternator Used for Capacitor Charge Power Supply

Research on the Excitation Control of Brushless Doubly-Fed Alternator in a Novel Pulse Capacitor Charge Power Supply