The dual active bridge (DAB) converter operating with a relatively high switching frequency is well suited for deriving a high-power density electric vehicle (EV) charger. In this case, safeguarding the realization of zero voltage switching (ZVS) for a wide operating range becomes crucial to ensure a good performance in terms of efficiency and control reliability. Unfortunately, most modulation schemes available today in the literature require a detrimental compromise in the achievable ZVS range, particularly the ones working mainly toward the minimization of the current stress. Due to the fact a public EV charger will work with multiple vehicles having quite different charging profiles, i.e., with wide operational voltage and currents ratings, the ZVS operation may be prone to fail to undermine the whole cycle charging efficiency. To relieve the issues, this article proposes a new modulation scheme for the DAB converter featuring a maximized ZVS range and a quasi-optimal inductor rms current. Herein, the concept of dynamic settings of the required modulator's ZVS-current is utilized and a straightforward implementation with seamless circuit mode transition is achieved. With the above characteristics, the dynamic and static losses of the component circuits can be reduced together. By adopting the dynamic ZVS-current settings strategy, the turning- on currents of the DAB switches are adjusted in real-time guaranteeing the ZVS operation under various operating conditions. With the seamless transition, the inductor current can be smoothly regulated to ensure system stability. The proposed modulation scheme is introduced, analyzed, validated, and benchmarked in a 4.5 kW/100 kHz SiC-based DAB prototype, whose peak efficiency can reach 96.3% when operated at partial load.

This article proposes a mode-switching-based phase shift control (MS-PSC) for wireless power transfer (WPT) systems, which is able to achieve power regulation, load matching, and wide ZVS operations simultaneously without using additional dc–dc converters. Based on the mode transitions between the full-bridge, mixed-bridge, and half-bridge modes of both the inverter and the rectifier, the MS-PSC method guarantees a wide-range ZVS with minimized circulation of reactive power. Therefore, the system efficiency is improved over a wider power range compared to the conventional triple-phase-shift (TPS) control and the existing hybrid modulation control. The principles of different operating modes are analyzed. Then, the implementation of the proposed MS-PSC method and the mode selection strategy are presented. Finally, the effectiveness of the proposed MS-PSC method is validated in a WPT prototype. Experimental results show that the proposed MS-PSC method can achieve a high overall efficiency in a wide power range. Compared with the conventional TPS control, the MS-PSC method further optimizes the efficiency in 10%–63% of the rated power, with efficiency improvements ranging from 1.5% to 6%. As a result, the system efficiency remains at 93.5%–96.1% in the power range of 1–10 kW, with the transformer coupling coefficient k = 0.19.

Traditional Class-E circuit features fewer components, high reliability, and soft switching. However, due to the unidirectional excitation, the application of such a topology circuit is limited, i.e., usually used in low-power applications. To relieve this issue, this article proposes a switched-capacitor-based Class-E circuit, to extend the operating power range of the Class-E circuit. With the proposed new circuit, both constant current (CC) and constant voltage (CV) output modes can be achieved by switching the branch once without changing the switching frequency or compensation network. Compared with the existing CC and CV charging strategies, the proposed circuit has the advantages of fewer components, simpler implementation, and higher reliability. Moreover, the studied compensation network can also be extended to other inverter topologies. The working principle of the proposed circuit is described in detail, and the variable zero-voltage switching (ZVS) margin is introduced to make an accurate design of parameters. Subsequently, the influence of high-order harmonic components on the circuit and the sensitivity of parameters are analyzed. Finally, the proposed circuit is simulated and experimented on a 180–450-W prototype with CC and CV characteristics to verify the feasibility of the circuit and the accuracy of theoretical analysis.

The advancement in modulation strategies brings emergent solutions to suppress the leakage current in three-phase two-level transformerless grid-connected voltage source inverters (VSIs). However, most of the techniques are analyzed based on reduced common-mode voltage pulse width modulation in motor drivers but fail to satisfy the specific requirement of grid-connected applications such as wider power factor operation and lesser current distortion. To overcome such substantial drawbacks, this paper proposes a novel scalar PWM method for transformerless grid-connected VSIs. Firstly, presented through a generalized scalar approach with unified zero-sequence voltage generation, the method is simple to implement and favored in practice. Besides, systematic and comprehensive mathematical analysis is illustrated to exhibit the validity of implemented method in reducing leakage current and shows its advantages over whole power factor range in terms of DC-link current harmonic, output current quality, and switching losses. Finally, simulations and experimental results are carried out to verify the effectiveness and superiority of the proposed method.

The dual-side inductor–capacitor–capacitor (LCC) topology circuit has been widely adopted in wireless power transfer (WPT) systems due to its constant output current characteristic. However, most conventional control methods need specific synchronization techniques between the primary and secondary sides to avoid the oscillation in the system, which increases the cost and control complexity. To solve this issue, this article proposes a new duty cycle control (DCC) strategy for a dual-side LCC resonant converter with a semibridgeless active rectifier (SAR). With such a control strategy, gate signals of the primary- and secondary-side circuits do not need to be synchronized, which could reduce the complexity and the cost of the WPT system. Besides, the switching frequency of the secondary side can be decreased significantly. This article first presents the modal analysis of phase shift control (PSC) and DCC. Then, generalized state-space averaging (GSSA) modeling with PSC and the hybrid average modeling with DCC are performed. In addition, controllers’ design for both strategies is conducted to achieve the constant output voltage. Finally, the eigenvalues’ analysis is used to determine the stability region of the WPT system. The theoretical analysis has been validated by both simulation and experimental results.

Common-mode voltage (CMV) problem brings severe negative effects in three-phase voltage source inverters (VSIs), particularly for high frequency Silicon Carbide (SiC) VSIs. However, most traditional CMV reduction strategies, which are studied based on Silicon VSIs, are hard to be implemented and sacrifice the other performance of the VSIs. To overcome such drawbacks, this paper proposes a novel generalized tri-state pulse width modulation (GTSPWM) for high frequency SiC VSIs over power factor of 0-1 and whole linear modulation index range. The working principle of conventional space vector based reduced CMV PWM (RCMV-PWM) methods are reviewed, and their switching signals and CMV patterns are illustrated. The proposed GTSPWM method is described in generalized scalar PWM approach for simple application and compared with other RCMV-PWM methods. Mathematical analysis, simulations, and experimental results have been used to verify that GTSPWM based high frequency SiC VSIs can achieve minimum switching losses, improved output waveform quality, smaller DC-link current ripples, and reduced CMV characteristics. Moreover, with the usage of GTSPWM method, the switching frequency of SiC VSIs can be further increased, and the performance of high frequency SiC VSIs could be improved appreciably.