Control of Electrically Excited Synchronous Motors with a Low Switching Frequency

Yuan, Qing-Qing,Wu, Xiao-Jie,Dai, Peng,Fu, Xiao The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.

Rotor Initial Position Estimation Based on sDFT for Electrically Excited Synchronous Motors

Qing-qing Yuan,Xiao-jie Wu,Peng Dai 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3

Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.

Control of Electrically Excited Synchronous Motors with a Low Switching Frequency

Qing-qing Yuan,Xiao-jie Wu,Peng Dai,Xiao Fu 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component (im) and the torque component (it). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between im and it. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.

Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency

Yuan, Qing-Qing,Xia, Kun The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $i_d$ and $i_q$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $i_d$ and $i_q$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.

Rotor Initial Position Estimation Based on sDFT for Electrically Excited Synchronous Motors

Yuan, Qing-Qing,Wu, Xiao-Jie,Dai, Peng The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3

Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.

Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency

Qing-qing YUAN,Kun XIA 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components id and iq with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for id and iq is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.

CONVERGENCE OF ISHIKAWA ITERATION WITH ERROR TERMS ON AN ARBITRARY INTERVAL

Yuan, Qing,Cho, Sun-Young,Qin, Xiaolong Korean Mathematical Society 2011 대한수학회논문집 Vol.26 No.2

In this paper, a continuous real function on the real line is considered. The necessary and sufficient conditions for the convergence of the Ishikawa iteration with error terms for the functional are obtained.

Sublethal effects of beta-cypermethrin on the bird cherry-oat aphid Rhopalosiphum padi (Hemiptera: Aphididae)

Qing-Qing Zhang,Wen-Qiang Li,Zeng-Bin Lu,Li-Li Li,Yi Yu,Chao Li,Xing-Yuan Men 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.3

Rhopalosiphum padi is a sap-sucking aphid and an important pest of wheat that causes considerable yield loss. Beta-cypermethrin, a synthetic pyrethroid pesticide, has a broad insecticide spectrum and is considered effective for aphid control, while its residual concentrations may have sublethal effects on R. padi. Here, the sublethal effects of beta-cypermethrin on R. padi were conducted under laboratory conditions. The acute toxicity test showed that LC 10 , LC 20 , and LC 25 of beta-cypermethrin to R. padi adults were 0.003, 0.031 and 0.079 mg L −1 , respectively. The pre-adult survival rate was significantly reduced by all three concentrations. LC 20 significantly extended the development duration of 1st instar nymphs, pre-oviposition period, and oviposition period of R. padi. The adult longevity was also reduced by LC 25 . However, the fecundity did not differ between the betacypermethrin treatment and control. For life table parameters, both the finite rate (λ) and intrinsic rate of increase (r) decreased at LC 10 and LC 20 , as well as the net reproductive rate (R 0 ) reduced at LC 10 and LC 25 , while mean generation time (T) increased at LC 20 . Thus, at the concentrations of beta-cypermethrin tested here, there were negative impacts on R. padi fitness by decreased pre-adult survival rate, λ, r, and R 0 , and delayed the development of some stages and increased T.

Adaptive ILC Design for Nonlinear Discrete-time Systems With Randomly Varying Trail Lengths and Uncertain Control Directions

Qing-Yuan Xu,Jing Cheng,Yun-Shan Wei,Kai Wan 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9

In this paper, an adaptive iterative learning control (ILC) design method is proposed for a class of nonlinear discrete-time systems with nonaffine structure, randomly varying trail length, and uncertain control direction. In order to achieve repetitive tracking control of the nonaffine structure systems with uncertain control direction, randomly varying trail length, and other uncertainties, we apply a high-order neural network to approximate the expected system input. Then, a novel adaptation law is designed for the neural network weight vector. The main feature of the method proposed in this paper is that the weight vector norm instead of the weight vector itself is updated iteratively to realize the successive approximation of the expected system input, the custom-designed identification mechanism is not necessary to deal with the uncertain control direction, and the analysis of randomly varying trail lengths problem is strictly established. The convergence of the proposed adaptive ILC is set up by a composite energy function. The effectiveness of the proposed adaptive ILC design is validated by two simulation examples.

Removal of elemental mercury using TiO₂-based nanofibers from coal combustion flue gas

( Yuan Yuan ),( Yong Chun Zhao ),( Ji Hua Qiu ),( Ya Qing Qiu ),( Chu Guang Zheng ),( Jun Ying Zhang ) 한국폐기물자원순환학회 2023 I-CIPEC Vol.2012 No.0