Journal of Power Electronics最新文献

Fault diagnosis plays a significant role in improving the reliability of T-type three-level inverters. Therefore, a method for diagnosing the IGBT open-circuit faults of T-type three-level inverters based on vector 3D offset is proposed in this paper. The characteristics of the voltage vector shift in single-switch open-circuit faults under three-dimensions are analyzed. In the first dimension, the fault phase was identified by the different offset of three-phase voltage vectors at the polar coordinates. In the second dimension, the output voltage vectors were mapped to the common-mode voltage level in space, and faulty bridge arms were identified by the transition direction of the common-mode voltage. In the third dimension, the specific faulty transistor within a set of bridge arms was identified by the voltage difference between the upper and lower capacitors on the DC side, which was caused by the regional shift of the voltage vectors in the plane. Experimental results show that the proposed method can effectively diagnose the OC faults of 12 switches in T-type three-level inverters. The key advantages of the proposed method are its capability to significantly enhance fault diagnosis speed, bolster diagnostic robustness, and remain impervious to variations in load and modulation coefficients. Moreover, it eliminates the need for additional sampling circuits.

This paper addresses the issue of lag caused by the sampling phase deviation in BUCK converter digital twin-parameter identification, and proposes a phase compensation method to improve digital twin-parameter identification. After sampling the characteristic signals of the BUCK converter, the proposed method introduces a Hilbert transform to compensate for the phase deviation in both the physical converter and the digital twin converter signals. By performing phase compensation before calculating the fitting degree of the digital twin, this method reduces the impact of phase deviation on the fitting degree calculation, allowing the fitting degree to more accurately reflect the true differences among converter signals. This reduces the computational redundancy caused by phase deviation and enables the digital twin converter to promptly update parameters. In addition, a BUCK converter digital twin platform is designed for experimental validation. Experimental results demonstrate that the proposed improved digital twin-parameter identification method saves 50% of optimization iterations when compared to traditional methods without compromising accuracy. This indicates that parameter identification can achieve accurate results with fewer optimization iterations, effectively enhancing the speed of digital twin converter parameter identification and facilitating subsequent converter-field coupling analysis.

In inductively coupled power transfer (ICPT) systems, the mutual inductance and load are the key parameters to realize high performance control, which is difficult to measure directly in rail transit. Thus, a method realizing mutual inductance and load identification using only the output voltage and current of a high-frequency inverter is proposed in this paper. Dual-frequency modulation, where one is the resonant frequency and the other is the non-resonant frequency, is used in the high-frequency inverter. Then the amplitudes and phases of the output voltage and current of the high-frequency inverter at the resonant frequency and the non-resonant frequency can be obtained based on the fast Fourier transform (FFT) method. The circuit is decomposed according to different frequencies. Then a mathematical model of the ICPT system is established. Therefore, the mutual inductance and load can be identified. Finally, the effectiveness of the proposed method is verified based on an ICPT prototype. Experimental results show that the identification errors of mutual inductance and load are less than 5%.

This paper presents a new common-mode voltage (CMV) suppression strategy based on open-active vectors, which reduces the CMV peak value and suppresses the common-mode spikes caused by switching. In addition, the novel open-active vector is characterized, and its common-mode equivalent circuit is established. The new modulation strategy proposes open-active vectors in place of zero voltage vectors, which reduces the peak magnitude of the output CMV by 42.3%. While reducing the CMV, the complex commutation issue of the rectifier stage and the CMV spike issue brought on by the impact of the inverter stage dead zone are both resolved by the new modulation method. The effectiveness of the new strategy is verified by simulation and experimental results.

In medium and high voltage DC microgrids, the input series output parallel dual active bridge (ISOP-DAB) converter, as one of the key devices, has received more and more attention from experts and researchers. This is due to the power imbalance and poor dynamic performance of each module of ISOP-DAB converters. Based on the double-loop decoupling strategy, this paper proposes a hybrid control strategy of a super twisting sliding mode considering backflow power optimization. First, the power model and ZVS characteristics of the DAB converter in two modes under extended phase-shift modulation are analyzed, and a reduced-order model of the DAB converter is established on the basis of the transmitted power model. Second, an output voltage loop super twisting sliding mode controller and a backflow power optimization module are designed based on the established mathematical model. Finally, simulation results show that the ISOP-DAB system has good dynamic performance in load switching and input voltage mutation, can ensure the input voltage of each sub-module, and can effectively reduce the backflow power.

In this study, two new structures are proposed for reverse-conducting insulated gate bipolar transistors (RC-IGBT) that effectively prevent snapback by relocating the N-collectors and utilizing silicon–germanium in the collector region of each device. The forward mode of the proposed structures shows I_C− V_C characteristics without snapback, since the position of the N-collector is changed to prevent electron extraction. In the reverse mode, the silicon–germanium induces currents through tunneling and impacts the ionization mechanisms. Importantly, the proposed structures generate a stable current value even if there are errors in the length of the N-collector during ion implantation, which enhances the reliability of the device. In addition, the proposed structures exhibit similar values for the breakdown voltage at around 700 V and the turn-on and turn-off losses when compared to the conventional RC-IGBT. Thus, this paper improves the reliability of RC-IGBTs by mitigating the snapback effect while maintaining their unique electrical properties.

The optimization of planar transformers with integrated magnetic components is an important research focus when it comes to high efficiency and high power density step-down DC–DC converters. In this paper, to overcome the shortcomings of LLC topologies in variable frequency operation, a DC–DC converter of two-stage regulation with GaN (gallium nitride)–MOSFET is designed to achieve wide voltage range conversion. The planar transformer of the full-bridge LLC circuit is optimized at 12 V DC bus and high-power scenarios. An equivalent resonant inductance model based on the stray inductance and JMAG leakage inductance simulation is proposed, which results in only one magnetic component being used in the LLC. A method to control the resonant inductance and improve the efficiency by changing the PCB trace on the secondary side of the high-step-down-ratio (14:1:1) planar transformer is proposed. To verify the optimization model, two sets of converters with optimized planar transformers, using PQ-type ferrite magnetic cores, have been built. Experimental results show that the voltage conversion range is from 250–500 to 9–16 V, and the converter efficiency is increased to 94.39%@3 kW.

Predicting the capacity and temperature of lithium-ion batteries is of critical significance to ensure their safety and stability, and consequently, extend the service life of battery systems. However, the degradation of capacity and thermal performance is typically regarded as independent processes, disregarding their coupling relationship. In response, this study constructs a combined model based on convolutional long short-term memory for the joint prediction of the reversible capacity and peak discharge temperature of batteries. The model’s feature extraction and pattern reconstruction capabilities are well-acknowledged. A variety of charging and discharging features (e.g., current, voltage, temperature, and incremental capacity) are analyzed and correlated with the evolution trends of battery capacity and temperature during long-term operation. Moreover, the evident phenomenon of capacity regeneration caused by intermittent rest is considered. Finally, the prediction results for different cells from public datasets show that the root-mean-square errors of capacity prediction vary from 0.01179 to 0.03304, and the mean absolute percentage error of peak discharge temperature prediction can be basically kept lower than 0.6%.

VSI-operated IM drives at low switching per fundamental frequency in a quarter cycle (N_s) are highly prone to lower order harmonic torque in addition to torque ripple. This can lead to lower efficiency, reduced service life, wear and tear of the components, acoustic noises and vibrations, etc. It can also lead to shaft failure in the long run. Thus, it is the preeminent consideration in prevailing high-speed, motor and power drives. Presently, these problems are minimized by implementing classical PWM techniques (CB-PWM and SHE-PWM). In this present paper, a P-PWM-based approach is proposed for the reduction of the harmonic magnitude in the lower order torque and the torque ripple in VSI-operated IM drives. In this paper, a programmed pulsewidth modulation (P-PWM)-based approach is applied in the context of three switchings per fundamental frequency per quarter cycle (N_s = 3) for reducing the harmonic magnitude (lower order) and ripples in torque that are of the order of the 6th, 12th up to 6(N_s − 1)th. Since the P-PWM approach relies on independent specifications and loading states, it can accommodate different N_s and higher order harmonics. Furthermore, the P-PWM performance is implemented and extensively compared with carrier-based pulsewidth modulation (CB-PWM), and selective harmonic elimination pulsewidth modulation (SHE-PWM) for N_s = 3 and the obtained findings are supported by a 1hp VSI-based IM drive using a TYPHOON-HIL based experimental setup. The P-PWM approach surpasses the classical used PWM techniques, such as CB-PWM and SHE-PWM, both in terms of the magnitude of the harmonic and the ripples in the torque.

Low-speed operation of induction motors (IM) requires special treatment to maintain their performance. The use of the indirect field-oriented control (IFOC) method makes the IM reliable in a variety of conditions, but the performance of IFOC is dependent on the reliability of the dq-axis controller, which is part of IFOC. Therefore, this research offers the implementation of the grey wolf optimizer (GWO) method to optimize the PI controller on the d-axis side. The data from this method is compared to the conventional PI method for evaluation. The results show that the GWO-PI and conventional PI method have the same steady-state value (SSV) and error (SSE). The implementation of the GWO-PI method reduces the integral absolute error (IAE) by up to 0.36% and the current consumption by 3.96–10.62%. As for the rise time and settling time aspects, the implementation of GWO-PI provides improvements of 0.001–0.02 s for rise time and 0.08–0.362 s for settling time. This indicates that the implementation of the GWO-PI method on the d-axis controller of the IFOC method can optimize the performance of IM speed and reduce current consumption in the case study of low-speed operation.