Owing to its advantages such as simple structure, strong robustness and good dynamic and static performances, model predictive control (MPC) has been widely applied to three-phase voltage source PWM rectifier systems. However, the PI linear regulator adopted in the voltage outer loop of MPC affects the dynamic performance of DC-side voltage. Aimed at this problem, a virtual torque impulse balance control strategy is proposed to achieve a rapid convergence of DC-side voltage through only one time of regulation. To realize this strategy, the expression of virtual torque is derived based on the mathematical model at first. Second, the virtual torque impulse balance control equation under load mutation is analyzed and established according to the fact that the DC-side output voltage will remain unchanged before and after load mutation while combining the principle of power conservation. Afterwards, the acting time of zero and forward vectors can be obtained. Finally, the virtual torque impulse balance control of the three-phase voltage source PWM rectifier system under load mutation is realized through simulations and experiments, which verifies the correctness and effectiveness of the proposed algorithm.

In power electronic devices, high-speed switching will often lead to serious electromagnetic interference (EMI) problems, which seriously affects the reliability of power electronic systems. To solve these EMI problems, EMI filters are a common solution. The insertion loss is an evaluation index for the noise attenuation capability, and the accuracy of its model directly affects the parameter design accuracy of EMI filters. To improve the prediction accuracy of the EMI filter insertion loss model, accurately describe the system behavior and predict the filtering performance of the EMI filter, and improve the design efficiency of the EMI filter, the insertion loss of a single-stage differential-mode EMI filter is modeled using a back propagation neural network. The proposed neural network model has better practical application value than the ideal model and the behavioral model of a high-frequency circuit, aiming to provide guidance for the design and optimization of EMI filters. This model can quickly evaluate the actual insertion loss of EMI filters to improve their design efficiency.

Aimed at the problem that the switching frequency under the min-type switching law is too high to be applied in engineering practice, a switched system model of Boost converter operating in continuous conduction mode (CCM) is established, and a novel switching law based on common quadratic Lyapunov function is proposed. According to the mathematical expression of the switching law, the steady-state and dynamic performances of the converter are analyzed, and the regulation mechanism of the converter's switching frequency under the switching law is described. Simulation and experimental results show that under the proposed switching law, the Boost converter's switching frequency is controllable and the Zeno behavior which is specific to a switched system would not occur. Compared with those under the existing control strategies, the converter under the proposed strategy has a good dynamic performance, with fewer voltage fluctuations and a shorter settling time when suffering external disturbances.

The new generation of wide bandgap power semiconductors such as SiC and GaN are driving the rapid high-frequency, high-efficiency, and small volume development of power electronic equipment. However, they are also more likely to interfere with sensitive loads, affect wireless communication, and even endanger their own safety and reliable operation, which poses great pressure and challenges to the electromagnetic compatibility (EMC) performance of power electronic equipment. In recent years, the radiated frequency(RF) characteristics of power switches, wideband electromagnetic models of magnetic components, electromagnetic radiation mechanisms of switched mode power supplies, near-field characteristics of wireless power transmission(WPT), and the new designs of electromagnetic interference(EMI) filters have become current research hotspots and received continuous attention from academia and industry. The Journal of Power Supply has specially released the album "Electromagnetic Compatibility in Power Electronic Systems" to promote the exploration of difficult and hot issues in the field of EMC analysis and design of power electronic systems.

In the background of environment protection and power-saving awareness, the requests for new energy electric vehicles and their on-board charger(OBC) keep growing. As one of the important components in the OBC module, magnetics is getting more and more attention accordingly. The magnetics integration of differential mode (DM) and com-mon mode(CM) chokes for a 3-phase 4-wire (3P4W) electromagnetic interference(EMI) filter used in OBC is theoretically analyzed and studied. Based on the analysis and comparison of the background of power supply applications, the inte-gration principle for DM and CM chokes, and the available integration schemes in industry and academia, an integration of DM and CM chokes for 3P4W with quasi-cross DM magnetic branches is proposed. Through the magnetic flux simula-tion analysis, electrical characteristics under DC-bias and the on-board tested data, the effect of the magnetics integra-tion scheme was proved, i.e., it can obviously decrease the DC-bias on DM magnetic branches in the case of unbalanced 3-phase current and effectively improve the anti-EMI performance of power supply.

The adjustment of energy structure is an important issue for China's energy development in the 21st century, in which the development of renewable new energy is an important means to optimize the energy structure and reduce environmental pollution. Nowadays, lithium-based batteries are still the main devices that can achieve reversible storage of renewable energy, whose electrochemical performance is often affected under harsh environmental conditions such as different temperatures, mechanical stress and humidity. As a result, problems including the damage of battery components, capacity fading, short-circuit explosion, and thermal runaway will occur. The failure mechanism of lithium-based batteries under harsh environmental conditions is systematically analyzed. Then, the main methods for improving their electrochemical and safety performance are reviewed. Finally, the urgent problems to be solved are summarized. This paper provides ideas for the failure mechanism research on lithium-based batteries as well as the development and applications under harsh environmental conditions.

The inconsistency of line parameters at the outlet of distributed generator(DG) and its random output disturbance lead to a decrease in load power distribution accuracy of DC microgrid and grid-side voltage fluctuation. Aimed at these problems, a double-factor droop control strategy based on adaptive characteristics is proposed with the consideration of the transient-and steady-state of DG operation. First, the influence of line impedance is taken into account during the steady-state operation, a voltage regulation coefficient is introduced, and the steady-state component of double-factor droop coefficient is established. The exact distribution of load power can be realized when the impedance value is unknown, and the grid-side voltage can be raised to reduce the difference with the rated voltage. Second, the influence of random disturbance of DG output is considered in the transient process, and the distributed consistency iterative algorithm is introduced to establish the double-factor droop coefficient free component, which can quickly suppress the power disturbance and grid-side voltage fluctuation while maintaining the balanced output from DG, thus improving the system stability. Finally, a DC microgrid model is built in PSCAD, and simulation results show the effectiveness of the proposed strategy.

The lithium-ion battery equalizer based on switched inductor is still of strong practical value in low-power portable electrical equipment. However, the switching devices in the equalizer operate in a hard-switching state under traditional control strategies. A soft-switching implementation algorithm for battery equalizer based on switched inductor in continuous current mode is proposed. The determinants of the inductor current of the equalizer and the charging and discharging current of a battery cell are analyzed. Then, a soft-switching implementation algorithm for the switching devices in the equalizer is proposed, and its control accuracy is analyzed. The equivalent impedance and open-circuit voltage of the battery cell can be obtained in real time by detecting the change rate of battery cell voltage and charging current, which further ensures the accuracy of the algorithm. Experimental results show that the proposed soft-switching control algorithm has a good performance.

The triple active bridge(TAB) DC-DC converter based on the phase-shifting plus duty cycle control strategy has advantages such as a high efficiency and an expandable soft switching range. However, its small signal modeling process is complex, and the parameter setting of closed-loop control loop is difficult. To solve these problems, a full-orer continuous generalized state space average modeling and PI controller design method for TAB converter under phase-shifting plus duty cycle control is proposed. First, the operation principle and Y-type equivalent structure of the TAB converter are analyzed. Second, combined with the characteristics of phase-shifting plus duty cycle control and the equivalent method of AC square wave source, the generalized state space average model of the TAB converter is derived. Third, based on the derived model, the transfer function from input to output is obtained, and the parameters of PI controller are designed. Finally, the correctness and effectiveness of the proposed method were verified by digital simulations and prototype tests.

The stability of an urban rail transit traction power supply system is related to the safety of urban power grid and the stable operation of traffic. Due to the large amounts of cables and a series of power electronic devices which have been put into use, problems such as harmonics and reactive power will arise and seriously damage the safety of the traction power supply system. As the core equipment of the traction power supply system, the traction transformer has important functions such as transmitting power supply and filtering nonlinear load harmonics. DC bias is a widespread phenomenon adversely affecting the traction transformer, and it may directly threaten the safe and stable operation of the traction transformer. Based on PSCAD/EMTDC and ANSYS, the UMEC model and finite element model of a novel traction transformer are established, respectively. By means of multi-platform hybrid simulation, the electromagnetic, loss and other excitation characteristics of this traction transformer under DC bias are observed and analyzed. With a comparison with the traditional traction transformer, the excitation situation of the novel traction transformer under DC bias is evaluated.