The traditional finite element model of permanent magnet synchronous generator（PMSG） needs nonlinear iteration for each grid, and time-consuming. Besides, the performance of various components of the voltage regulator controller (VRC) will be affected by the operating environment. The traditional component library cannot meet the accurate digital twin effect. Taking an emergency power supply system for an unmanned aerial vehicle as an example, this paper uses the device-level modeling method to build a digital twin simulation model (DTSM) of a PMSG and its AC-DC regulated power supply system, which simulation speed can guarantee real-time output results in synchronization with the experiment, and has an agile digital twin effect. Finally, the calculated results are compared with the experimental values to verify the accuracy of the proposed digital twin device-level model, which is of great significance to the combined design of PMSGs and VRCs. Index Terms：Permanent magnet synchronous generator (PMSG); Digital twin ;Voltage regulator controller. I. Introduction The performance of permanent magnet synchronous generator (PMSG) is closely related to its control method and load characteristics. When the AC-DC step-down chopper voltage stabilization control strategy is adopted, it can ensure the output of stable DC power while reducing the three-phase line current of the generator, reducing the motor winding loss greatly, and optimizing the matching design of the generator and the power converter. The power stabilization system is stable and efficient. Therefore, the research of PMSG and its AC-DC conversion and voltage stabilization system (VSS) simulation can promote the development of PMSG and VSS technology, improve system design accuracy effectively, and realize the perfect match to improve the stability and reliability of the VSS [1][2][3][4]. II. Composition of VSS Circuit After studying the load characteristics and actual working environment, the power supply system adopts a PMSG combined with a three-phase uncontrolled rectifier bridge and a BUCK converter. The actual power supply system consists of PMSG, three-phase uncontrolled bridge rectifier circuit, power regulator circuit, filter circuit, feedback circuit, control circuit, drive circuit and auxiliary power supply circuit. III. Digital Twin Device-Level Simulation Modeling In order to improve the simulation speed of the simulation model and achieve a fast digital twin effect, this paper uses the ECE reduced-order model extraction method to convert the generator finite element model into a data matrix model, and establishes the PWM main control chip SG1525 and the device-level modeling method. The digital twin simulation model (DTSM) of the AC-DC VSS of the PMSG is built as shown in Fig.1. The simulation speed can ensure the real-time output results in synchronization with the experiment results, and realize the fast and accurate digital twin effect. IV. Experimental Verification The PMSG and its VSS were tested on a dedicated test bench, which is shown in Fi.g. 2. The oscilloscope is used to display the output DC voltage waveform in real time, and the DTSM is run on the computer at the same time. The simulation data is highly consistent with the measured data. V. Conclusion This paper proposed a high-precision DTSM based on the actual prototype of an emergency power supply system for an unmanned aerial vehicle. Firstly, the ECE reduced-order mathematical model is extracted by the alternating-direct-axis periodic current scanning method, which accelerates the simulation speed greatly. Secondly, according to the actual circuit structure of the emergency voltage stabilization control power converter, a DTSM of the entire VSS circuit is built. Finally, the accuracy of the DTSM is verified by experiments.The reduced-order model extraction and device-level modeling techniques used in this paper are in line with the development trend of digital twin technology. The research results can provide a reference for the design of PMSG and the optimal matching design of VSS.

**References:**

[1] A. Rassõlkin, V. Rjabtšikov and T. Vaimann. "Digital twin of an electrical motor based on empirical performance model,"2020 XI International Conference on Electrical Power Drive Systems (ICEPDS), Saint Petersburg, Russia, 2020. [2] N. Khaled , B. Pattel and A. Siddiqui. “Digital twin development and cloud deployment for a DC motor control embedded system”, 2020. [3] R. Goraj. “Digital twin of the rotor-shaft of a lightweight electric motor during aerobatics loads”, Aircraft engineering and aerospace technology, 2020. [4] N. Khaled , B. Pattel and A. Siddiqui. “Digital twin development for an inverter circuit for motor drive systems”, Digital Twin Development and Deployment on the Cloud, PP. 163-201, 2020.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/82e16107aa4d5c0d5770a5259dc1f38a.jpg)
Fig.1. The DTSM of the AC-DC VSS of the PMSG.

![](https://assets.underline.io/uploads/markdown_image/1/image/bccf3f35c4be885acb6e6910cdef3814.jpg)
Fig.2. The test bench of PMSG and its VSS.

 Quickly and High-Precision Digital Twin Device-Level Simulation Modeling of Permanent Magnet Synchronous Generator and Voltage Stabilizing System

In this paper, a 40kW, 36000rpm high-speed permanent magnet synchronous generator（HSPMSG） with the ambient temperature of 350 Celsius is taken as an example to study the accurate calculation of iron loss. Considering the influence of high temperature and high frequency on the loss and electromagnetic performance of electromagnetic materials, the corresponding iron loss coefficient is fitted according to the variable coefficient iron loss separation model. Then, based on the field-circuit co-simulation method, the influence of switching frequencies and modulation ratios on the iron loss characteristics of the HSPMSG under the conditions of SVPWM modulation is studied. The calculation accuracy of the iron loss is improved. Finally, the effectiveness of the proposed method is verified by the experimental results, which provides a reference for the precise analysis of iron loss of the same type of HSPMSG. I. Introduction High-speed permanent magnet synchronous generators have drawn more and more attention due to the advantages of high-power density and high efficiency in the fields of aerospace applications. However, due to the poor heat dissipation conditions, it may lead to the excessive temperature of the PMs and increase the risk of irreversible demagnetization. A method combining 2-D nonlinear finite element analysis with 3-D frequency-domain harmonic analysis is proposed in [1], the motor loss under the influence of the harmonic field generated by the inverter is calculated. The iron loss analysis of HSPMSM considering the influence of multi-physical factors is proposed in [2], but the influence of harmonic current under inverter PWM modulation is not considered. The total loss value of a 100kW, 32000rpm HSPMSM is calculated by numerical analysis and verified by test results in [3], but it did not separate the calculation of each loss. The novelty of this paper is as follows. Considering the influence of temperature and frequency on the iron loss. The influence of switching frequencies and modulation ratios on the iron-loss characteristics of high-temperature HSPMSG under the conditions of SVPWM modulation is studied based on the method of field-circuit coupling co-simulation, which improves the calculation accuracy of the iron-loss of the HSPMSGs. II. Loss Performance Test The magnetization and loss characteristics of electromagnetic materials are not only related to temperature, but also related to frequency. Therefore, it is necessary to evaluate the temperature-frequency-magnetization characteristics and temperature-frequency-loss characteristics of electromagnetic materials. The loss characteristics of 1J22 soft magnetic alloy materials at the frequency of 1000Hz is shown as Fig.1. III. Variable Coefficient Iron Loss Separation Model In this paper, based on the orthogonal decomposition model, an improved variable coefficient orthogonal decomposition model is used to study the iron core loss, which takes into account the magnetization mode and the skin effect, and the variable coefficient orthogonal decomposition model suitable for calculating the iron loss of the HSPMSG is obtained. IV. Iron Loss Calculation and Analysis Based on the field-circuit co-simulation method, the influence of switching frequencies and modulation ratios on the iron loss characteristics of the HSPMSG under the conditions of SVPWM modulation is studied. The calculation accuracy of the iron loss is improved. V. Experimental Verification The HSPMSG test platform was built as shown in Fig.2.And the iron loss of the HSPMSG was tested. The test results are in good agreement with the calculated results, which verifies the accuracy of the previous calculation results. VI. Conclusion In this paper, the loss characteristics and electromagnetic performance of electromagnetic materials under high temperature and high frequency are tested, and the corresponding iron loss coefficients are fitted according to the variable coefficient iron loss separation model. Based on the field-circuit co-simulation method, the influence of switching frequencies and modulation ratios on the iron loss characteristics of the HSPMSG under the conditions of SVPWM modulation is studied, and the accuracy of the calculation method is verified by comparison with the test results, which is of great significance for the accurate analysis of the iron loss of the HSPMSGs.

**References:**

[1] K. Yamazaki and S. Watari, "Loss analysis of permanent-magnet motor considering carrier harmonics of PWM inverter using combination of 2-D and 3-D finite-element method," IEEE Trans Magn, vol. 41, no. 5, pp. 1980-1983, May 2005. [2] G. Liu, M. Liu and Y. Zhang，"High-speed permanent magnet synchronous motor iron loss calculation method considering multi-physics factors, " IEEE Trans. Ind. Electron., vol. 67, no. 12, pp. 10109–10120, Dec. 2020. [3] Z. Huang, Fang. J and Liu. X, "Loss calculation and thermal analysis of rotors supported by active magnetic bearings for high-speed permanent-magnet electrical machines," IEEE Trans. Ind. Electron.,vol. 63, no. 4, pp. 2027-2035, Apr. 2016.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/10719caf61cd41d320a186c9d5decd07.jpg)
Fig.1. The loss characteristics of 1J22 at the frequency of 1000Hz

![](https://assets.underline.io/uploads/markdown_image/1/image/7dac747d1f6a146b243fddb8fa08e4ef.jpg)
Fig.2. The HSPMSG test platform

 Accurate Calculation of Iron Loss of High Temperature and High Speed Permanent Magnet Synchronous Generator Under the Conditions of SVPWM Modulation

Compared with the conventional motors used on the ground, the DC starter-generators (DCSGs) for aero-engines have higher electrical, thermal, magnetic and mechanical loads. Excessive electrical loads will increase the armature response of the (DCSGs) and worsen the commutation, thus shortening the lifetime and reducing the reliability of the (DCSGs). In order to improve the lifetime and reliability of the (DCSGs), this paper studied the effects of commutator structure, compensation windings, commutating poles and brush sizes on commutation effect of DCSGs based theory analysis combined with numerical analysis. Then effective measures to improve the commutation performance of this type of DCSGs are proposed, and the commutation spark observation test of a certain type of DCSGs verifies the effectiveness of the optimization design measures proposed in this paper. Index Terms：DC starter-generators (DCSGs); Brush; Commutation; Optimal design. I. Introduction The DC starter-generators (DCSGs) used in aero-engine is installed on the engine accessory box. When the aero-engine starts, it acts as a starter motor to drive the engine to ignite. After the engine ignites, it acts as a generator to supply power to the aircraft network. Due to the special application environment of the DCSG, it has the characteristics of low voltage and high current compared with the motor used on the ground. The commutation process is extremely bad, and it may produce larger commutation sparks or even ring fire, shortening the lifetime of the brush and reducing the operational reliability of DCSGs[1][2][3][4]. This paper optimizes the design of parameters such as commutator structure, commutating pole winding and brush size, and studies the influence of parameter changes on the commutation performance of DCSGs under the conditions of low voltage and high current, and discusses the effectiveness of improving the commutation performance of this type of DCSGs The method provides a reference for commutation spark suppression in commutation of the same type of DCSGs. II. Large Current Commutation Modeling The electromotive force and current in the armature winding of the DCSG form an AC-DC voltage and current conversion through the cooperation of the commutator and the brush. This conversion process is called commutation. There is a complicated electromagnetic process in the commutation process, and reactance electromotive force is generated in the commutation element. By reducing the armature reaction and adjusting the brush width to reduce the reactive electromotive force, the commutation spark can be reduced and the commutation performance can be improved. III. Optimal Design Take a 9kW, 6250rpm～12000rpm DCSG as an example to study the influence of commutator structure selection, compensation winding, commutating pole and brush size on DCSG commutation performance. Finite element analysis model of the DCSG is shown in Fig.1. IV. Experimental Verification A start-up test was carried out on the simulated engine load characteristics of a 9kW a DCSG. The test bench is shown in Fig.2. No visible commutation sparks were observed in the test, which verified that the effectiveness of the commutation performance optimization design method proposed in this paper. V. Conclusion This paper studies the optimization design of DCSG to improve its commutation performance. Based theory analysis combined with numerical analysis, the influence of different commutator types, compensation windings, commutating pole windings and brush parameters on the commutation performance of the DCSG is analyzed. The prototype is tested for starting and generating performance. The experimental results verify the effectiveness of the optimized design method in improving the commutation performance, which can provide a reference for improving the commutation performance of the same type of DCSG, and is useful for improving the operating reliability and lifetime of the DCSGs.

**References:**

[1] Takashi, Fukutsuka and Yasunobu. “Arc discharge during commutation process in DC motor immersed in ethanol: approach to contact state of brush on commutator segment”, IEEJ Transactions on Power and Energy, Vol. 139, pp.293-301,2019. [2] H. Kim, H. Kim and W. Moon. “Design optimization of brush permanent magnet DC motors using response surface method”, Journal of Magnetics, vol. 25, pp. 355-362, 2020. [3] K. Sawa, M. Isato and T. Ueno. "Commutation characteristics and brush wear of DC motor at high rotation speed," 2017 IEEE Holm Conference on Electrical Contacts, pp. 176-181, 2017. [4] Z. Qingliang, Takahiro and Ueno. “The new commutation theory to the optimization technique of the large DC machine commutation design”, IEEJ Transactions on Industry Applications, Vol. 131, pp. 654-666, 2011.

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/246f78fbf529af15431c6c92f934689e.jpg)
Fig.1. Finite element analysis model of the DCSG.

![](https://assets.underline.io/uploads/markdown_image/1/image/acbe807bc1de68577c1c67ffac5a574f.jpg)
Fig.2. Test bench of DCSG.

 Research on Optimal Design of Commutation Performance of Starter-Generator Used in Aero-Engine

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Quickly and High-Precision Digital Twin Device-Level Simulation Modeling of Permanent Magnet Synchronous Generator and Voltage Stabilizing System

Accurate Calculation of Iron Loss of High Temperature and High Speed Permanent Magnet Synchronous Generator Under the Conditions of SVPWM Modulation

Research on Optimal Design of Commutation Performance of Starter-Generator Used in Aero-Engine

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