Asymmetric Duty Modulation (ADM) opens up new opportunities for DAB converter to improve steady-state performance. Triple phase shift (TPS) modulation, which belongs to symmetric duty modulation (SDM), can minimize the inductor RMS current. However, the soft-switching range is still limited at light load. A unilateral asymmetric triple phase shift (UATPS) modulation strategy combining ADM and SDM is proposed in this paper to reduce the RMS inductor current while expanding soft-switching range. Firstly, typical waveforms of UATPS are generated by combining ADM and SDM, and the steady-state characteristics are derived in time domain. Secondly, a mathematical model for optimization is established, and the global optimal solution is obtained based on the Karush-Kuhn-Tucker (KKT) condition, and the direct power control strategy of the UATPS is proposed. Finally, the experimental results verify the effectiveness of UATPS to improve the efficiency.

To balance the instantaneous power difference between the pulsed output power and the constant input power of the pulse load power supply (PLPS), an active capacitor converter (ACC), which can compensate the pulsed current, is connected in parallel with the output of the dc–dc converter in the PLPS. In this article, based on the Fourier decomposition results of the load current, it is evident that the square waves have significant harmonic content. Hence, to provide the lower impedance at the frequencies of the high content harmonics in the load current, a virtual impedance that consisted of the multiple quasi-notch-filters is proposed to be in parallel at the port of the ACC for the suppression of output voltage drop and input current ripple. The virtual parallel impedance is implemented by the output voltage feedforward control of the ACC. The design considerations of the virtual parallel impedance are presented to ensure the stability of the PLPS. Finally, a synchronous rectifier buck converter with a bidirectional buck/boost converter is tested at the pulse repetition frequency of 100–300 Hz and the pulse duty cycle of 0.15 to verify the validity of the proposed control scheme.

When the power supply works in the application of pulse load, a large output voltage drop and low-frequency input current pulsation will be generated by the pulsed power. Moreover, the normal operation of equipment will be affected, especially for multi-pulse-loads. A two-stage pulse load power supply (PLPS) is introduced to suppress the output voltage drop and input current pulsation, the mediate capacitor not only can buffer the pulsed power but also the capacitance can be reduced by increasing the ripple on that. To further reduce the output voltage drop, the model predictive control (MPC) for the back-end converter is proposed, which has the advantage of fast dynamic response and unregulated control parameters. Finally, to verify the effectiveness of the proposed control scheme, a prototype for two pulse loads is fabricated in the lab with pulsed power at 400 W.

In the application of ultralow-frequency pulse load with reversed power, the pulse load is directly supplied by the battery. However, the random and multistate instantaneous output power results in voltage fluctuation across the battery. The uncontrollable reversed power will cause irreversible damage to the battery. To satisfy the requirements for voltage fluctuation, the active power compensator (APC) is introduced to provide pulsed power and absorb reversed power. The hybrid decoupling control scheme composed of linear current control and nonlinear voltage control is proposed for the APC, which can suppress the voltage overshoot and undershoot effectively when pulse repetition frequency or instantaneous output power changes. To improve the stability of the system at the mode transitions, several methods are proposed in the control scheme. The methods of updating integral error directly and the step control aim to accelerate the process during mode transients. Finally, to verify the effectiveness and viability of the proposed control scheme, a prototype is fabricated in the laboratory with pulsed power at 2250 W, reversed power at 1350 W, and pulse repetition frequency at 1.6–1.8 Hz.

To balance the instantaneous power difference in the pulse load power supply (PLPS), an active capacitor converter (ACC) is adopted to compensate the pulse current. In this paper, to improve the tracking ability of the ACC, a fast inductor current step control scheme is used with digital controller, and its transient operation process is analyzed. Finally, a prototype with the output peak power of 157W, the pulse frequency of 50–500 Hz and pulse duty cycle of 0.1-0.3 is fabricated and tested to verify the validity of the proposed PPS and control schemes.

The input power of the pulsed power supply system (PPS) is required to be constant, and its output power is pulsed. To balance the instantaneous power difference, the single-inductance active capacitor unit (ACU) is often connected in parallel to the output of the PPS. However, the single-inductance ACU has a transient process of the current reverse of the inductor, which will lead to serious output current spikes of the pre-stage power supply system. In this paper, the dual-inductance ACU is adopted in place of the single-inductance ACU to suppress the transient process of inductor current reversal. In order to improve the dynamic performance and reduce the tracking error of the compensation current of the dual-inductance ACU, a nonlinear feedforward PID control strategy is proposed. Finally, an experimental prototype is built to verify the validity of the proposed pulsed power decoupling topology and its control strategy.

Multi-input converter combining various ambient sources, is considered as an effective approach to solving the problem of the sporadic and intermittent exist in energy harvesting. This paper proposes a multi-input variable structure to harvest vibration energy, which can work in dual sources parallel mode (DIPM), dual input series mode (DISM), and single source mode (SIM). In this work, GaN is adopted to eliminate power loss caused by body diodes of MOSFETs. The steady-state performance and input power of three modes are derived, it concludes that DIPM has the highest power which is different from traditional applications and DISM provides a wider working range. Due to the range of voltage variations in the energy harvesting process, the change of three modes can match the input and output power dynamically. Otherwise, the optimal power extraction strategy and energy management method based on impedance adjustment in discontinuous conduction mode (DCM) is used to improve the energy harvesting efficiency. An experimental prototype with simple control is built to verify the feasibility and performance of the proposed variable structure.

The output power of the pulsed power supply (PPS) pulsates at the pulse repetition frequency (PRF) of pulse load. The pulsating power will result in a large bus voltage ripple. To balance the instantaneous power difference, a single or dual-inductance active storage unit (ASU) is usually connected in parallel with the output terminal of the PPS. Poor compensating current tracking accuracy of ASU will lead to the output current of PPS suffered from serious current spikes, which affects the stability of the bus voltage. A hysteresis current control (HCC) is proposed to achieve an excellent pulse current compensation performance. Compared with the current mode control (CMC), the small-signal modeling of dual-inductance with HCC is established to illustrate good compensation performance. Besides, a valley voltage loop is introduced to regulate the storage capacitor voltage in dual-inductance ASU to reduce the power loss at any pulse duty cycle. An experimental prototype is built to verify the spikes in output current can be eliminated effectively, the bus voltage keeps smooth and stable, and the output capacitor of the per-stage DC/DC converter is reduced significantly.

Due to the input power and output power do not match in real time, single-stage power factor correction converters have large double-line-frequency ripple at the output voltage. The double-line-frequency ripple voltage will cause some electronic devices to work abnormally, and limit the control loop bandwidth of power factor correction converter. In order to reduce the output double-line-frequency ripple voltage, a single-stage Flyback power factor correction converter with Buck ripple suppressor is used in this paper, the Buck ripple suppressor can generate same magnitude but 180° phase shifted voltage as Flyback power factor correction converter output voltage ripple. Adaptive on-time control is adopted in the Buck ripple suppressor benefiting with its wider bandwidth and fast dynamic response. The switching frequency range and stability of Buck ripple suppressor under constant on-time control and adaptive on-time control are discussed. By establishing the input-output audio susceptibility model, the output double-line-frequency ripple suppression performance is analyzed. Buck ripple suppressor using adaptive on-time control can suppress double-line-frequency ripple voltage effectively with the fast dynamic response and high efficiency. Simulation and experimental results are given to verify the theoretical analysis.

This paper describes a systematic procedure using power flow graphs for generating all possible Power Management Units (PMUs) for the Internet of Things (IoT) applications. to maximize the generality of applications, a series of topologies with battery (three ports) and without battery (two ports) are proposed in detail. The operating modes of different topologies are analyzed and summarized in this paper, which provide the meaningful reference of PMUs for IoT applications. Finally, experimental results are presented to verify the analytical results.

This paper proposed a deep learning algorithm system to fulfil fake news and misinformation detection on COVID-19 related headlines. Long short-term memory (LSTM), convolutional neural network (CNN) and Deep belief networks (DBNs) are performed in order to determine the optimal algorithm. Based on the model performance measures, such as accuracy, AUC score, and F1 score, this study figures out the optimal models, which are CNN and LSTM with an accuracy of up to 94%, for the COVID-19 fake news detection. Finally, this paper provides an algorithm-based ranking method for mainstream media credibilities. The result indicates that mainstream media channels in the US are reliable for reporting the COVID-19 related news and information.

The surface of nodular cast iron was strengthened by means of surface melting and alloying with plasma beam.The microstructures and the phase structures were analysed with SEM and XRD.The corrosion resistance and wear properties as well as microhardness were tested by hardness tester and wear tester.The results show that the near-surface graphite of the nodule disappears completely and there are mainly dendrites and eutectics in the modified layers after surface treatment of nodular cast iron by plasma beam.The highest microhardness in the melted layer and alloyed layer,appearing in the subsurface,are 1243HV0.1and 1343HV0.1,respectively.The corrosion resistance and wear resistance of the melted layer and alloyed layer are enhanced remarkably comparing with the matrix.Furthermore,the corrosion resistance and wear resistance of the alloyed layer are better than that of the melted layer due to more hard phases,finer and more homogeneous structures in the alloyed layer.