Soft Start and Synchronous Switching of Permanent Magnet Synchronous Machines without Damping Windings

Ronggang Ni,Gaolin Wang,Hanlin Zhan,Guoqiang Zhang,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes the extending application of permanent magnet synchronous machines (PMSMs) without damping windings, or non-line-start PMSMs (NLSPMSMs) to achieve effective soft start and synchronous switching from inverter drive to grid drive. The system electromechanical model during switching is deduced, and numerical analysis is adopted to verify the stability under grid drive. For the control strategy, two phase lock loops (PLLs) are adopted to obtain the phases of gird and inverter voltages. Then speed and current regulation is exerted to minimize the difference between inverter output and grid. Experiment results show that the 37kW NLSPMSM prototype can be safely switched to grid drive and robust to large load variation. Tested waveforms are coincident with numerical analysis.

Nonlinear Dynamic Analysis of a Trochoid Cam Gear with the Tooth Profile Modification

Ronggang Yang,Bo Han,Jiawei Xiang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.12

A trochoid cam gear (TCG) is a kind of precise transmission device with high performance, such as non-backlash, high precision, low noise, etc. Generally, the tooth profile modification technique is essential to influence the dynamic performance of TCG, which has not been studied. In the present, the equations of tooth profile modification are constructed to analysis the nonlinear dynamics of the TCG. Firstly, the tooth profile modification equation is deduced according to the requirement of meshing impact reduction. Secondly, considering the time-varying principal curvature radius of tooth profile and the nonlinear relationship between forces and deformations, a translation-torsion nonlinear dynamic model is established to further construct the nonlinear model of TCG. Finally, the dynamic characteristics of the TCG with three key parameters (the damping c , the radius d r of roller and the short amplitude coefficient K ) are investigated. The tooth profile modification technique proposed herein can improve the system stability. Moreover, by increasing c and K , or decreasing d r , the performance of TCG can be improved to maintain stable motion state.

No-backlash characteristics analysis of a cycloidal ball planetary transmission under axial pre-tightening

Ronggang Yang,Naige Wang,Jiawei Xiang 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.4

Cycloidal ball planetary transmission (CBPT) has many applications as precision reducer, such as precision machinery and automation drive systems etc. The traditional analytical model of CBPT cannot accurately describe the change of the normal force of meshing points, and thus cannot describe the precise transmission process of meshing pairs. In the paper, a method for deriving the normal force equation is put forward by using the non-linear relationship between force and deformation in elastic mechanics. The two-point contact analytical models of all the meshing pairs are established to obtain the micro-displacement analytical model of CBPT under axial pre-tightening. Then, the non-real-time two-point contact analytical models of all the meshing pairs are further constructed to obtain the normal force expression to determine the critical compression coefficients. Experimental investigations are performed to verify the analytical model using the critical compression coefficients.

The MPEG Internet Video-Coding Standard [Standards in a Nutshell]

Wang, Ronggang,Huang, Tiejun,Park, Sang-hyo,Kim, Jae-Gon,Jang, Euee S.,Reader, Cliff,Gao, Wen IEEE 2016 IEEE signal processing magazine Vol.33 No.5

<P>To address the diversified needs of the Internet, the ISO/IEC JTC1/SC29/WG11 Moving Picture Experts Group (MPEG) started the project of Internet video coding (IVC) in July 2011. It is anticipated that any patent declaration associated with the baseline profile of this standard will indicate that the patent owner is prepared to grant a free-ofcharge license to an unrestricted number of applicants worldwide. IVC has been developed in MPEG from scratch by combining well-known existing technology elements and new contributions with free-of-charge licenses. Recently, IVC's compression performance has been determined to be approximately equal to that of the advanced video coding high profile (AVC HP) for typical operational settings, both for streaming and lowdelay applications. In June 2015, the IVC project was approved as ISO/IEC 14496-33 (MPEG-4 IVC). It is believed that this standard can be highly beneficial for video services in the Internet domain. This article describes the main coding tools adopted in IVC; evaluates its performance compared with web video coding (WVC), video coding for browsers (VCB), and AVC HP; and provides the subjective comparison results between IVC and AVC HP.</P>

Regenerative-Cooling Heat-Transfer Performance of Mg/CO2 Powder Rocket Engines for Mars Missions

Supeng Zhu,Ronggang Wei,Chunbo Hu,Chao Li 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

Aimed at the problem of thermal protection due to the long-time operation of Mg/CO2 rocket engines under high pressure and heat flux, a regenerative-cooling heat-transfer model is established that considers liquid-CO2 phase change under engine heat flow. How the height-to-width ratio of the cooling channel and the coolant mass flow rate influence the heat-transfer performance is studied, and the results show that the CO2 experiences liquid-phase, two-phase boiling, and gas-phase heat transfer. It is necessary to carry out division-of-region design to avoid membrane-boiling or gas-phase heat transfer in the cooling channel for a long time. When the coolant enters the nuclear boiling stage of two-phase heat transfer near the throat, the heat-transfer coefficient reaches its maximum value, as does the temperature of the corresponding combustor wall, which is 918.1–1012.3 K. When the CO2 flow rate exceeds 5 g/s, the continuous increase of coolant flow has a limited increase in the heat-transfer coefficient of liquid and two-phase heat transfer, but continuing to increase the CO2 flow rate can expand significantly the occurrence region of phase-change heat transfer, so as to bring better heat transfer.

Initial Position Detection of Permanent Magnet Synchronous Machines with Self-Tuning Extended State Observer

Yawei Wu,Yifan Cui,Ronggang Ni,Shuxin Nie,Xinzhen Wu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The performance of the initial rotor position detection of Permanent Magnet Synchronous Machines (PMSMs) at standstill depends much on the position observer. In this paper, the Extended State Observer (ESO) is compared with the traditional Proportional Integration (PI) observer adopting the rotating high frequency voltage injection algorithm, and the observer parameter design method is derived based on the bandwidth analysis of the close-loop transfer function. Experiments are carried out on a 3 kW PMSM prototype for verifications.

Adaptive Notch Filter Based Harmonic Self-Compensated Sliding-Mode Observer for Position Sensorless IPMSM Drives

Guoqiang Zhang,Gaolin Wang,Ronggang Ni,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

To suppress the position error harmonic ripples in back electromotive force (EMF) based methods for position sensorless interior permanent magnet synchronous motor (IPSMSM) drives, an adaptive notch filter (ANF) based harmonic self-compensated sliding-mode observer (SMO) is proposed. The inverter nonlinearities and flux spatial harmonics that induce the position error harmonic ripples are analyzed. The back-EMF information containing harmonics can be obtained through SMO, and then the least mean square (LMS) based ANF is adopted to realize back-EMF harmonic detecting and selfcompensating, thus eliminating the position error harmonic ripples. Due to the simple structure, the ANF based harmonic self-compensated SMO can be easily implemented on low-cost microchips with little computational burden. Experiments on a 2.2kW IPMSM sensorless vector controlled drive have been carried out to verify the proposed scheme.

Offline Inductance Identification of PMSM with Adaptive Inverter Nonlinearity Compensation

Gaolin Wang,Ying Wang,Jiangbo Qi,Ronggang Ni,Wei Chen,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Offline inductance identification of permanent magnet synchronous motor (PMSM) is essential for self-tuning of closed-loop controller and position observer in sensorless vector controlled drives. This paper proposes an enhanced offline identification method fulfilled at standstill with adaptive inverter nonlinearity compensation for general-purpose drive applications. The d-q axis inductances can be obtained at standstill by using a voltage-sourceinverter fed drive. Influences of inverter nonlinearities on direct and quadrature inductance identifications exploiting high frequency (HF) voltage injection at different rotor positions are analyzed. Then an adaptive inverter nonlinearity compensation strategy employing a simple self-learning of compensation coefficients is proposed to enhance the accuracy of inductance identification. The feasibility of the proposed adaptive offline inductance identification method is validated on a 22kW interior PMSM.

Numerical Calculation of Stator End Leakage Reactance of Permanent Magnet Machines with Concentric Winding

Xiaoqin Zheng,Wen Zhang,Xinzhen Wu,Ronggang Ni 한국자기학회 2019 Journal of Magnetics Vol.24 No.1

Concentric winding has been widely used in small capacity AC motors due to its excellent performance. In this paper, a numerical calculation method based on the magnetic vector potential is proposed to calculate the stator end leakage reactance of concentric winding. In this case, the basic unit of numerical calculation becomes the coil group rather than the coil since concentric windings have different coil sizes. The calculated stator end leakage reactance of a prototype three-phase permanent magnet machine with concentric winding is validated using the finite element method. Compared to 3D electromagnetic field calculation, the proposed method does not require a complex modeling process and is therefore highly efficient computationally, requiring only a fraction of the calculation time.

Harmonic Analysis of the Effects of Inverter Nonlinearity on the Offline Inductance Identification of PMSMs Using High Frequency Signal Injection

Gaolin Wang,Ying Wang,Li Ding,Lei Yang,Ronggang Ni,Dianguo Xu 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

Offline inductance identification of a permanent magnet synchronous motor (PMSM) is essential for the design of the closed-loop controller and position observer in sensorless vector controlled drives. On the base of the offline inductance identification method combining direct current (DC) offset and high frequency (HF) voltage injection which is fulfilled at standstill, this paper investigates the inverter nonlinearity effects on the inductance identification while considering harmonics in the induced HF current. The negative effects on d-q axis inductance identifications using HF signal injection are analyzed after self-learning of the inverter nonlinearity characteristics. Then, both the voltage error and the harmonic current can be described. In addition, different cases of voltage error distribution with different injection conditions are classified. The effects of inverter nonlinearities on the offline inductance identification using HF injection are validated on a 2.2 kW interior PMSM drive.