This study deals with the electromagnetic loss analysis through the coupling analysis of the controller motor considering the SVPWM control of a high-speed permanent magnet motor for driving a centrifugal pump. High-speed mechanical systems are suitable for applications such as compressors, vacuum pumps, turbine generators, flywheel energy storage systems, drilling machine tools, and electric vehicle propulsion motors in various industries such as transportation, defense, energy, aviation, and general industry. They are being developed for many industrial applications. It is not an exaggeration to say that the proportion of high-speed motors in the modern industry is on the rise. High-speed motors are operated by a power conversion device and a controller, and owing to the development of power conversion elements, high-speed and high-power motors are becoming possible [1]. In addition, there is a growing interest in the analysis of the loss and heat of high-speed motors in industry and academia. In the existing studies, the loss analysis of the motor is primarily performed through the current source analysis, which has the disadvantage of not considering the current harmonics caused by the switching of the controller. Therefore, it is difficult to predict the electromagnetic loss caused by current harmonics. In addition, few researchers have published a study on the characteristic analysis of the motor considering the current harmonics, but it is difficult to obtain accurate analysis results in all operating areas because only a single parameter of the motor is considered [2]. In addition, there is significant interest in reducing the loss and heat generation of high-speed permanent magnet motors. There are certain motor problems because of reduced efficiency and increased calorific value owing to electromagnetic losses that were not considered in the design stage. In particular, the heat generated in the rotating body of high-speed motors using sleeves in the industry is transferred to both bearings along the shaft. It also causes serious problems such as failure of bearings and shortening of life [3]. Hence, the electromagnetic loss analysis of the motor based on the controller and motor co-simulation analysis are important. Therefore, this study deals with the electromagnetic loss and dynamic characteristics analysis considering the inverter drive of a high-speed permanent magnet synchronous motor for a centrifugal pump. The motor and the SVPWM inverter were modeled, and the environment for the co-simulation analysis of the controller and the motor was established. The designed motor was manufactured, and the motor performance was evaluated. As illustrated in Fig. 1(a), a co-simulation analysis system was constructed using the analyzed motor model and the controller conceptual diagram. Results such as current applied to the motor according to the speed command and load torque, speed response characteristics, torque characteristics, and torque ripple were obtained. Fig. 1(b) depicts an experimental setup for the evaluation of a high-speed permanent magnet motor. The high-speed permanent magnet motor was combined with a centrifugal pump and a torque sensor and was operated through a controller. Fig. 1(c) presents the voltage and current waveforms of the motor measured in the rated speed and rated output range. It could be verified that the rated current was applied to the motor within the range not exceeding the voltage limit. Fig. 2(a) presents a comparison of the sinusoidal current and the incoming current waveforms of the motor during the coupling analysis. It could be verified that harmonics were included in the current waveform by the SVPWM switching frequency and were introduced into the motor. Fig. 2(b) shows the order and magnitude of the harmonic components included in the current waveform. Figs. 2(c) and (d) depict the analysis results of the loss of iron and permanent magnet rotors that occur during general sinusoidal current analysis and coupling analysis. Notably, the iron loss and eddy current loss increased owing to the harmonic components included in the current. Therefore, coupling analysis is important for detailed electromagnetic loss analysis. Based on the results presented here, it is judged that this study will contribute to the related industries by designing, developing, and evaluating the performance of a motor that can be used for industrial 12,500 rpm and 100 hp class centrifugal pumps. In addition, the co-simulation analysis method used in this dissertation is considered to be useful in the design of high-speed motors that can be applied to various industrial applications.

**References:**

[1] D.-K. Hong, D. Joo, Y.-H. Jeong, and D.-H. Koo, IEEE Transactions on Magnetics, vol.49, no.7, p. 4072, 2013. [2] Yunkai Huang , Jianning Dong , Long Jin , Jianguo Zhu , and Youguang Guo, IEEE Trans. Magnetics, Vol.47, No.10, October 2011. [3] Ziyuan Huang, Jiancheng Fang, Member, IEEE, Xiquan Liu, and Bangcheng Han, IEEE Trans. on Industrial Electronics, Vol.63, No.4, APRIL 2016.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/c832222bcfe2429056186ddf507e509b.jpg)
Fig. 1. (a) Concept diagram of the co-simulation analysis of motor including speed controller and current controller. (b) Motor performance test bed combined with centrifugal pump. (c) Motor voltage and current measurement results at rated speed and rated output.

![](https://assets.underline.io/uploads/markdown_image/1/image/9b1ae76ed958d99138172dea6058e43a.jpg)
Fig. 2. (a) Comparison of sinusoidal current and PWM current waveforms using co-simulation method. (b) Harmonic analysis result of motor current using co-simulation analysis. (c) Core loss analysis result according to current waveform. (d) Rotor loss analysis result according to current waveform.

 Electromagnetic Loss Analysis of High-Speed Permanent Magnet Motors for High-speed and High-head Centrifugal Pump using Co-Simulation Method with Controller

Linear oscillating actuators (LOAs) are devices that make reciprocating movements at a certain frequency. Therefore, LOAs can be classified according to the movement type, such as the moving-core type, moving-coil type, and moving-magnet type. The moving-core-type LOA has the advantage of easily increasing the permanent magnet usage and the output, but the price of the LOA becomes more expensive as the magnet usage increases. The moving-coil-type LOA has the highest output density compared to other types, but its disadvantage is that it is difficult to manufacture. Most LOAs used in practical applications are of the moving-magnet type. The moving-magnet type makes the mover light and suitable for high-speed operation, which is the most efficient way of increasing LOA output [1]. A novel design of a single-phase short-stroke LOA has been developed for application in refrigeration compressors and other similar equipment because of its advantages, such as high transmission efficiency and simple structure [2]. However, the performance of the LOA is difficult to evaluate due to its reciprocating linear motion. Additionally, unlike rotating machines, measuring the magnetic force of LOAs can be complicated. Therefore, LOA analysis and performance evaluation are essential not only via applying the finite-element method (FEM) analysis but also experimental verification. Experimental studies of the electromagnetic force and output of LOAs have been conducted by various researchers [3]. In this study, the structural and magnetic characteristics of a moving-magnet-type LOA are determined and verified through the analysis and experiment of mover stroke and current based on the operating frequency and applied voltage. Because the operation of the LOA is most efficient at the resonance frequency, it is essential to consider the operating frequency in the electromagnetic design. Finally, the change of the resonance frequency according to the mechanical load is confirmed, and the most efficient operation range is confirmed. Figure 1(a) illustrates the structure of the LOA. The LOA is fixed to the outer core, coil, and inner core, and has a structure in which the permanent magnet makes a linear reciprocating motion in the z-axis direction. The flux path and flux density are depicted in Figure 1(b). The permanent magnet makes a reciprocating motion in the z-axis direction and changes the direction of the main magnetic flux flowing in the outer core, which generates a counter electromotive force. Figure 1(c) shows a manufactured LOA component and experimental set. AC power is applied through the function generator and the voltage is amplified through the amplifier. The mover's stroke is measured through a displacement sensor. Figure 2(a) displays an analysis model considering the mechanical load of the LOA. The LOA is analyzed considering both the electrical system and mechanical load. The mechanical loads include the spring coefficient, damping coefficient, and mover mass. Under no-load conditions, the spring coefficient and mover mass act as mechanical loads, and the effects of force and damping from the loads are negligible. Figure 2(b) shows the current and stroke based on the applied voltage and frequency. Both cases show the most efficient operation at the resonance frequency. Therefore, the operating frequency of the LOA should be similar to the resonance frequency, and the LOA operation becomes less efficient as the difference between the resonance frequency and operating frequency increases. Detailed analysis and experimental results will be presented in the full paper.

**References:**

[1] J. Wang, D. Howe, and Z. Lin, “Design Optimization of Short-Stroke Single-Phase Tubular Permanent-Magnet Motor for Refrigeration Applications,” IEEE Trans. Industry App., vol. 57, no. 1, pp. 327–334, Jan., 2010. [2] T. Ibrahim, J. Wang, and D. Howe, “Analysis and Experimental Verification of a Single-Phase, Quasi-Halbach Magnetized Tubular Permanent Magnet Motor wit Non-Ferromagnetic Support Tube,” IEEE Trans. Mag. vol. 44, no. 11, pp. 4361-4387, Nov., 2008. [3] Z. Q. Zhu, and X. Chen, D. Howe, and S. Iwasaki, “Electromagnetic Modeling of a Novel Linear Oscillating Actuator,” IEEE Trans. Mag. vol. 44, no. 11, pp. 3855-3858, Nov., 2008.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/78af974295edeea6e81a05823492bbd8.jpg)
Fig. 1 (a) Analysis model of linear oscillating machine, (b) magnetic flux density and flow of linear oscillating machine due to PM, (c) outer core and experimental set.

![](https://assets.underline.io/uploads/markdown_image/1/image/54e8c4440204d478ec6729ed88cb4fd0.jpg)
Fig. 2 (a) Analysis model of linear oscillating machine considering mechanical load, (b) stroke and current analysis results and experimental results based on applied voltage and frequency

 Operating Characteristic Analysis and Verification of Short-Stroke Linear Oscillating Actuators Considering Mechanical Load

Wound rotor synchronous machines are widely used because of their advantages, such as simple control, cost efficiency, and stable operation [1]. Because of these advantages, the wound rotor synchronous generator (WRSG) is used in large factories, aircraft, ships, and hydroelectric power generation that require a large power supply [2]. The WRSG does not have a rare earth magnet, and it forms a magnetic field through the rotor winding, as shown in Fig. 1(a). A magnetic field is formed by applying current to the rotor windings through an exciter, and the magnetic flux density can be controlled using the exciter to increase the power density. The core of many electrical machines is made of electrical steel with nonlinear characteristics, and the magnetic flux density must be adjusted to a level where the core is unsaturated to satisfy the user’s desired output power, efficiency, and voltage. Therefore, it is necessary to evaluate the electromagnetic characteristics through electromagnetic analysis during the initial design. Finite element analysis (FEA) software is commercially available because it can obtain accurate analysis results that reflect nonlinearity. However, FEA consumes significant analysis time in the initial design, in which the design parameters change frequently [3]. Therefore, in this study, we propose a nonlinear magnetic equivalent circuit (MEC) to predict the electromagnetic and power generation characteristics of the WRSG. The magnetic equivalent area was divided according to the magnetic path of the WRSM (Fig. 1(b)). The paths through which the magnetic flux passes are divided into stator, rotor, air-gap, and interpolar regions. The magnetic flux inside the circuit could be calculated using the magnetomotive force(MMF) and reluctance, and the flux density in air gap could be calculated using the magnetic flux. Fig. 2(a) shows a comparison of the air gap flux density derived through the MEC and FEA when a field current is applied. The air flux density derived for the MEC represented the flux density waveform when the rotor position rotated, which could be used to derive the stator flux linkage waveform according to the rotor position. The derived flux linkage induced a back electromotive force (EMF) at no load (Fig. 2(b)). In the initial position, the rotor was positioned such that the flux linkage to the windings of one phase was maximized, and the back EMF through the flux that varied according to the rotation of one slot pitch was derived. The back EMF was influenced by the MMF of the rotor winding, and beyond the linearly increasing region, it became saturated because of the nonlinearity of the core material. The back EMF derived from the nonlinear MEC increased linearly and then nonlinearly, owing to saturation beyond a certain field current (Fig. 2(c)). The back EMF obtained using the nonlinear MEC was compared with those obtained through FEA and experimental measurements; the comparison validates the nonlinear MEC proposed in this study. It is necessary to determine the values of the back EMF, inductance, and phase resistance, which are equivalent circuit parameters, to predict the power generation characteristics of a WRSG. A MEC based on the rotor position must be constructed to reflect the inductance that varies with the rotor position, owing to the salient structure of the WRSG. Fig. 2(d) shows the prediction results of power generation characteristics using the inductance derived through the MEC, back EMF, and phase resistance. The FEA results indicated the power generation characteristics in the low-voltage regulation rate region, and the MEC results were in good agreement with the FEA results. Even when the rotational speed of the WRSG changed, the MEC results were in good agreement with the FEA results. By predicting power generation characteristics, the speed and power required by the designer can be predicted, which is useful in the initial design. The nonlinear MEC and analysis results of the WRSG will be presented in further detail in the main paper.

**References:**

[1] S. Nuzzo, M. Degano, M. Galea, et al, IEEE Trans. Ind. Electron., vol. 64, no. 3, pp. 1958–1970, Mar. 2017. [2] A. Griffo, D. Drury, T. Sawata, et al, IEEE Trans. Ind. Electron, vol. 59, no. 9, pp. 3579–3587, Sep. 2012. [3] H.W. derbas, J.M. Williams, A.C. Koenig, et al, IEEE Trans. Energy Convers., vol. 24, no. 2, pp. 388–396, Jun. 2009.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/30110081fcfd5756909893a64d2ecd83.jpg)
Fig 1. (a) WRSG analysis model and rotor core experimental model; (b) Construction of nonlinear MEC

![](https://assets.underline.io/uploads/markdown_image/1/image/0abfb2acf0d58abdf081b148aaeb8928.jpg)
Fig 2. Comparison of electromagnetic characteristics obtained using the FEA, MEC, and experimental methods: (a) Comparison of air-gap flux density obtained using FEA and MEC methods; (b) Waveform of back EMF at rated speed of 900 rpm; (c) Variation of back EMF with field current; (d) Power-voltage curve

 Prediction of power generation performance of wound rotor synchronous generator using nonlinear magnetic equivalent circuit method

*Session Co-Chair: Chang-Hung Hsu, Oriental Institute of Technology*

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Presentations

Electromagnetic Loss Analysis of High-Speed Permanent Magnet Motors for High-speed and High-head Centrifugal Pump using Co-Simulation Method with Controller

Operating Characteristic Analysis and Verification of Short-Stroke Linear Oscillating Actuators Considering Mechanical Load

Prediction of power generation performance of wound rotor synchronous generator using nonlinear magnetic equivalent circuit method

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