In the case of high switching frequency, the bridge arm crosstalk caused by the parasitic parameters of SiC MOSFET in the traditional drive are more serious. However, most of the existing crosstalk suppression drive circuits suppress the crosstalk at the expense of increasing the switching loss, prolonging the switching delay and adding the control complexity. Therefore, based on the idea of reducing the impedance of the drive loop in the process of crosstalk generation, a novel active Miller clamp gate drive design is proposed by adding PNP triodes connected in series with diodes and capacitors between the gate and source, and its working principle is analyzed. The parallel capacitance parameters of the improved drive circuit are also calculated and designed. Finally, an experimental platform of double-pulse test for a synchronous Buck converter with DC bus voltage of 300 V was built, and the novel crosstalk suppression drive circuit was compared with the traditional and typical crosstalk suppression circuits in terms of the positive and negative crosstalk voltage spike suppression effects and the turn-on and turn-off speeds. Experimental results show that compared with those of the traditional and typical crosstalk suppression circuits, the positive and negative voltage spikes of the proposed crosstalk suppression drive circuit were reduced by 80% and 40%, respectively, and the switching delay of the device was reduced by 32% in the meantime.

A frequency regulation method for a large number of electric vehicles (EVs) in an isolated grid with high permeability renewable energy sources is proposed. First, a disturbance observer is designed for the system's order reduction model to generate additional frequency control signals for clustered EVs. This order reduction model is obtained by combining the changes in load, wind power, photovoltaic system and clustered EVs, thus generating a lumped disturbance estimated by the disturbance observer. Second, a robust model predictive control method based on the Tube model is proposed to provide effective control signals to improve the responsiveness of clustered EVs. The control signals are generated to obtain the minimum frequency deviation error by means of the minimum control actions while considering various physical constraints on the system operation. Third, the influence of time delay on communication link is studied through the stability analysis, and the time delay margin is obtained. Finally, through simulation analysis, the effectiveness of the proposed method is verified, and the advantages of the proposed method over traditional model predictive control, fuzzy proportional integral control and linear quadratic regulator control are also verified.

Based on the passive damping method of capacitor in parallel with resistor, the active damping method of virtual resistor in parallel with capacitor can complete the virtualization of shunt resistor using the control algorithm and realize the active damping of the resonant peak from the output filter through the capacitor current feedback. However, the existing method of virtual resistor in parallel with capacitor cannot achieve a strict equivalence of shunt resistance, which leads to the problem of poor dynamic performance. To solve this problem, through the transformation of the control block diagram, an active damping control method of fully equivalent shunt resistor based on capacitor voltage and capacitor current feedback is proposed, thus realizing the strict equivalence of passive damping method of capacitor in parallel with resistor. At the same time, the active damping control method of fully equivalent shunt resistor is obtained through the analysis of dominant poles of the system. Compared with the method of virtual resistor in parallel with capacitor based on the current loop, this method can effectively improve the damping ratio and response speed of the system while reducing the overshoot. Finally, simulation and experimental results verified the effectiveness of the proposed method.

The traditional coupling mechanism of multi-directional wireless power transfer (WPT) often adopts an xyz orthogonal circular coil structure, which requires three power supplies and has a charging area limited by the coil structure. To solve this problem, a novel multi-directional WPT coupling mechanism composed of two groups of 8-shaped coils and one group of circular coils is proposed. It presents five circular rings in different directions as a whole and only needs one single power supply. Based on the S-S type transmitter topology, the magnetic field distribution in the coil is changed by controlling the circuit, thus realizing power transfer inside and outside the coil and broadening the charging area. Based on the coil structure, a mathematical model of the proposed coupling mechanism is established, and the calculation formulas for mutual inductance and efficiency at any spatial position are derived. The best working area of the coupling mechanism is determined according to simulation and experimental results.

Although the LCL filter has a good performance of suppressing high-frequency harmonics, it may cause problems such as resonance oscillation and instability. For an LCL grid-connected inverter, the conventional capacitor-current-feedback type active damping method can suppress the resonant peak effectively, at the cost of additional current sensors. Under this background, a novel active damping control strategy based on an H∞ filter is proposed. The state space model and process noise model of the LCL filter are derived to solve the H∞ filter. The filter capacitor current can be estimated according to the information about grid current and the voltage at a point of common coupling, and feedback is further completed. The system damping is improved, and the estimation accuracy can be guaranteed even if parameter perturbations exist in the LCL filter. Simulation and experimental results show that the proposed method was insensitive to changes in the parameters of the LCL filter and the grid impedance, thereby verifying its feasibility and superiority.

Aimed at uncertainties in the output from grid-connected wind turbine, the scenario analysis method based on probability occurrence is adopted to transform the uncertainty model into a multi-scenario problem with different occurrence probabilities, and a reactive power optimization model with the goal of minimizing the active power loss and voltage deviation is established. In view of the poor diversity of Pareto frontiers obtained using the traditional methods, an adaptive grid multi-objective particle swarm optimization (AG-MOPSO) algorithm is proposed, which uses adaptive grids to obtain the density of particles in external archives, selects the global optimal particles and maintains the scale of the external storage library according to the density information as well as the betting mechanism, thus effectively ensuring the uniformity and diversity of the Pareto frontier distribution. This algorithm is used to perform reactive power optimization calculations on an IEEE 33-bus system with wind power, and it is also compared with the existing NSGA-II algorithm. Results show that the Pareto frontier obtained using this algorithm is better, which verifies the feasibility of the proposed model and algorithm.

At present, the transmitting coil in a dynamic wireless charging system for electric vehicles usually adopts a segmented guide rail structure to realize the relay dynamic wireless charging. However, the problem of mutual inductance drop will occur at the switching of the guide rail and result in the reduction of the system transmission efficiency, and this is more prominent at the corner. A corner dynamic wireless charging model was established, and the relationship between the mutual inductance of primary and secondary coils and the deflection angle was deduced through theoretical analysis. An improved structure of the guide rail transmitting coil at the corner was proposed and simulated, and a corner dynamic wireless charging platform based on resonance magnetic coupling was built. Simulation and experimental results show that by using the improved guide rail transmitting coil structure, the mutual inductance drop of the wireless charging system was significantly reduced, and the system transmission efficiency was improved by 8.66% at the maximum deflection angle, thereby verifying the effectiveness of the improved coil structure.

Aimed at the high harmonic content of a model predictive controller (MPC) without modulation modules, a novel model-based variable sampling period MPC strategy is proposed and applied to a five-phase induction motor drive system. The problem caused by the fixed-discretization of time in the MPC is analyzed, but the introduction of modulation or modulation substitution to solve this problem will increase the complexity of the control system. Therefore, a simpler and more natural idea is adopted. Specifically, the sampling interval is changed based on the pursuit algorithm, and the optimal control action and implementation time are determined by combining with the MPC, thus realizing the variable sampling period MPC strategy. Experiments were carried out using the five-phase induction motor drive system, and experimental results verified the excellent reference tracking and current harmonic performance of the novel variable sampling period MPC.

Aimed at the problems in the existing nine-level inverter such as many devices and a complex modulation strategy, a novel switched capacitor nine-level inverter is proposed. The topology of this inverter is composed of only one single DC power supply, nine switches, two capacitors and two diodes, and it can output nine levels and double the boost at the same time. The voltages of capacitors are self-balancing, and the complex control algorithm and external voltage sharing circuit are not required. The phase disposition PWM strategy is adopted to modulate the inverter. The working states of four pairs of switches in the inverter are complementary, and the NOT gate logic circuit can be used to reduce the complexity of the modulation strategy. First, the topology and working principle of the inverter are analysed theoretically. Second, the modulation strategy is introduced in detail, and the advantages of this topology are introduced by comparing it with other nine-level inverters. Finally, the feasibility and effectiveness of the proposed topology and modulation strategy were verified based on the established simulation circuit and experimental platform.

The dual-active-bridge (DAB) converter is a key device in a bidirectional power transmission system. In this paper, its fundamental operation principle and topologies are reviewed at first. Then, four basic modulation strategies for the DAB converter are introduced, including single-phase-shifted, dual-phase-shifted, extended-phase-shifted and triple-phase-shifted strategies. Moreover, the modeling and optimization methods based on these four modulation strategies are compared and analyzed. Finally, some problems faced by practical applications and the corresponding solutions are discussed. Along with the development of DC power distribution, energy storage and distributed energy resources, DAB converters will have broad application prospects.