Journal of Power Electronics最新文献

The phase-shifted full-bridge converter is often used as an on-board DC/DC converter because of its advantages of easy control and low loss. The use of a spread spectrum modulation technique can reduce the conducted common mode electromagnetic interference. However, the spectrum expansion of periodic pulse width modulation is not strong enough and is accompanied by spectral overlapping phenomenon in the high-frequency band. In addition, the chaotic pulse width modulation generates a large number of low-frequency components and the spectrum expansion is not controllable. In this paper, discrete chaotic sequences are used to modulate the modulation frequency of the periodic function for the second time to enhance the harmonic side-band extension capability of the periodic pulse width modulation, and to solve the problem of the accumulation of the low-frequency harmonic components caused by the chaotic pulse width modulation, and the introduction of the wide-band characteristics of the chaotic sequences can alleviate the overlapping phenomenon of the spectrum in the high-frequency band. Through the whale optimization algorithm, the relevant modulation parameters affecting the periodic-chaotic pulse width modulation–modulation frequency f_m and frequency extension range Δf are optimized. Finally, a 500W phase-shifted full-bridge converter experimental prototype verifies that period-chaos pulse-width modulation has better common mode EMI attenuation characteristics when compared with period pulse-width modulation and chaotic pulse-width modulation. In addition, it verifies the accuracy of the optimized parameters. The modulation means and optimization methods proposed in this paper can be used to reduce the conducted electromagnetic interference in switching power supplies.

The working conditions of the explosion-proof hoist inverter are particular. During heavy load and frequent lifting, power devices of the inverter will generate considerable power loss, which often leads to overheating or even damage to power devices and reduces the thermal stability of the whole system. This study proposes a quasi-deadbeat model predictive current control (QD-MPCC) strategy based on the neutral point clamped (NPC) three-level inverter. First, the QD-MPCC quasi-beat controller of the induction motor is designed, the digital delay compensation strategy is developed, and a closed-loop flux observer is adopted to improve the flux observation accuracy. Second, the traditional QD-MPCC strategy is improved. The loss model of the NPC three-level inverter applied to the explosion-proof hoist is established. Then the loss result calculated according to the predicted current is taken as the new control target, and the loss is dynamically optimized according to the operating curve. Finally, the robustness of the improved QD-MPCC strategy and its effectiveness in online power-loss management to improve the thermal stability of the system are verified by simulation and experiment.

This article proposes a multi-resonant three-port DC-DC converter (MRTPC) that can achieve power decoupling in the presence of deviations in the parameters of the resonant elements. The MRTPC consists of a four-element resonant tank (FERT), a three-element resonant tank (TERT), and an LC resonant tank (LCRT). Due to the fact that the FERT can be configured with first and third resonant frequencies (RF), it can transmit the energy of the fundamental and third harmonic components. By reasonably setting the RFs of the FERT, TERT, and LCRT, decoupling control of primary and tertiary energy transmission can be achieved. Due to the characteristics of the FERT, TERT and LCRT at different frequencies, decoupling the transmission of the power of the primary and tertiary frequency components can be achieved even when there is a certain deviation in the parameters of the resonant elements of the FERT. This feature can effectively reduce the cost of selecting resonant elements. To improve the efficiency of the MRTPC, an optimized triple-phase-shift modulation strategy (OTPSMS) is proposed to minimize the root mean square value of the resonant current (RMSRC). For the nonlinear problem of minimizing the RMSRC, the KKT condition is used for the optimization solution. Finally, an experimental prototype with a power level of 1 kW is built to verify the theoretical correctness of the MRTPC and its OTPSMS.

This paper proposes a fast dynamic DC-link voltage control strategy for dual three-phase permanent-magnet-assisted synchronous reluctance starter/generator (DTP-PMa-SRS/G) system. First, the model of a DTP-PMa-SRS/G is analyzed considering its asymmetric structure. A power balance strategy is adopted to solve the coupling problem between two sets of windings. Then the power model of the starter/generator system is analyzed considering the disturbance caused by inherent parameter uncertainty and external load variation. To improve the dynamic response performance of the DC-link voltage, an integral terminal sliding-mode DC-link voltage controller (ITSMVC) with an extended state observer (ESO) is proposed. The system stability is verified by Lyapunov theory. A simple parameter design method for the proposed ESO-ITSMVC is adopted to ensure satisfactory performance. Finally, a comparison of experimental results with the conventional ITSMVC, the active-disturbance rejection controller (ADRC), and the disturbance observer-ITSMVC (DO-ITSMVC) is carried out. The superior DC-link voltage dynamic response performance of the proposed method is verified.

This paper aims to analyze the inrush load current and develop an inrush current suppressor circuit optimized for a low-voltage DC (LVDC) distribution network. The connection of a substantial input capacitor in the DC load can induce a surge current, leading to significant issues in the LVDC distribution network, such as DC bus voltage drop and potential system damage. To address this issue, this paper presents the design of a voltage control system for a triple-active-bridge (TAB) converter in the LVDC distribution network, evaluating the need for the inrush current suppressor circuit. Control stability during the occurrence of the inrush current is analyzed using the small-signal model of the TAB converter. In addition, this paper proposes an inrush current suppressor circuit, presenting a design methodology to achieve the desired current suppression performance. Experiments are conducted on a laboratory-scale LVDC distribution network utilizing a 4-kW prototype converter to validate the performance of the suggested inrush current suppressor.

Wireless power transfer (WPT) technology has been extensively developed for unmanned aerial vehicle (UAV) application in recent years. However, misalignment tolerance has always been an unsolved problem for UAV wireless charging. In this paper, a coupling system attached to UAV landing gear is demonstrated. In the design process, a flexible curved coil has been designed for structure utilization. First, the magnetic induction strength of the arch bending coil is calculated. Then, an unequal turn spaced coil structure is proposed based on the genetic algorithm for parameter optimization. In addition, a 3D EM simulation is implemented for comparison before and after optimization. A resonance frequency of 75 kHz with an SS tuning topology is adopted in accordance with the Qi standard. Finally, the experimental setup is made and the results show that the UAV charging system has better misalignment tolerance.

Induction heating (IH) systems have been attracting more attention due to their direct heating capability. Moreover, IH systems have the advantages of fast heating performance, high efficiency, cleanliness, and safety. However, they also have the disadvantage of limited pot material, size, and misalignment. In general, IH systems cannot properly heat non-ferromagnetic pots because of their low resistance, which induces a large switch current. Third harmonic modulation (THM) is proposed to mitigate this issue. The conventional THM can heat low-impedance pots; however, it has drawbacks in high possibility of hard switching due to the high first harmonic current in the resonant tank. In this paper, a phase-shifted THM is proposed to improve soft switching and the maximum heating capabilities compared with the conventional THM by reducing the first harmonic component of the resonant current.

This paper proposes fractional delay filter-based repetitive controllers (FDF-RCs) for grid-tied converters. Finite impulse response filters and infinite impulse response filters are used to estimate the fractional-order delay filter in a conventional repetitive controller. To do this, both the Lagrange filter-based repetitive controller (LF-RC) and Thiran filter-based repetitive controller (TF-RC) are utilized as FDF-RCs to compensate a fractional delay. The operating principle, the ladder structure, and the performance analysis of FDF-RCs are addressed. The simulation and the experimental results on a single-phase grid-tied converter verify the harmonic suppression ability and reference-tracking performance of the proposed FDF-RC under the grid frequency variation. Moreover, the advantages of the TF-RC over the LF-RC are discussed by comparing and analyzing the simulation and experimental results.

This study proposes a new control strategy for the quasi Z-source two-level three-phase inverter, accurate discontinuous SVM (AD-ZSVPWM). The proposed AD-ZSVPWM control technique enhances the output power quality by reducing total harmonic distortion (THD) and conduction losses. Low THD is achieved by increasing the algorithm’s accuracy using a division of six vector states in each switching period and the distribution of six shoot-through states within the period. The conduction losses are reduced by splitting each sector into two subsectors of 30°. The proposed control scheme has the following advantages: reduced THD, low conduction loss, and increased boosting factor. MATLAB/Simulink software is used, and an experimental test is conducted to validate the proposed strategy. PLECS software is utilized to calculate the switching and conduction losses. For experimental verification, a hardware test bench comprising a dSPACE DS1104 board that controls a three-phase quasi Z-source inverter that supplies an R-L load is used. Simulation and hardware results show that the proposed scheme provides improved performance in terms of power quality and power loss reduction.

In low voltage distribution systems, series arc fault current is small and hidden, and traditional circuit protection devices cannot effectively identify it. To address this problem, a series arc fault detection method based on multi-domain depth feature association is proposed in this paper. By building an experimental platform, the current signal data on normal and arc fault states under different loads are obtained. The time-domain features, frequency-domain features and wavelet packet energy features of the current signal are extracted. To enhance the quality of the data, the importance of each domain characteristic is ranked using four distinct tree techniques, and the most useful features are chosen. A one-dimensional stacked neural network (1D-SNN) fault detection model is constructed to further extract the depth features of each domain. To achieve series arc defect detection, the depth features are combined and fed into a fully connected neural network. The Radam algorithm is used to optimize the detection model. It is then compared with Adam, SGD, and RMSprop optimization algorithms, which verifies that Radam has a better effect on the optimization of the arc detection model. Experimental results show that the average detection accuracy is 99.63%.