Inductive power transfer (IPT) technologies have gained a wide acceptance in onboard battery charging applications due to some significant advantages over traditional plug-in systems. An IPT battery charger is expected to provide a configurable charging profile consisting of an initial constant current (CC) and a subsequent constant voltage (CV) efficiently. With a wide load range during the charging process, two sets of IPT topologies with the inherent load-independent CC and CV at the same zero-phase angle (ZPA) frequency are commonly combined into a hybrid topology to avoid sophisticated control schemes, while maintaining nearly unity power factor and soft switching of power switches simultaneously. However, the load-independent CC and CV are usually constrained by parameters of a loosely coupled transformer (LCT), making the LCT hard to design. To solve it, this paper systematically presents a method to derive such effective hybrid IPT converters, which starts from some existing topologies having the configurable CC or CV output and cascades a general T network for mode transition. Design principles with fewer mode switches and compensation components are proposed and some available hybrid topologies regardless of the constraint of LCT parameters are given in this paper. Control logic and sensitivities of compensation parameters to the input impedance and the load-independent output are also discussed. Finally, a 1 kW hybrid IPT battery charger prototype based on LCC-LCC and LCC-S topologies is built to verify the theoretical analysis.

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.

A LCC-S compensated wireless power transfer (WPT) system with dual decoupled receive coils and a cascaded PWM regulator is proposed in this paper. The dual decoupled receive coils, comprising of bipolar coil and unipolar coil, provide two power paths. Most of input power is transferred to load directly through bipolar coil while only small portion of input power is transferred through unipolar coil and the cascaded PWM regulator, which can reduce power loss effectively. The output voltage of WPT system is regulated by the cascaded PWM regulator, thereby wireless communication links (WCLs) is not required in the feedback control loop, which leads to simple control circuits and good stability. Compared with conventional WPT system with two-stage power conversion, it is cost-effective as voltage/current stress of PWM regulator can be significantly alleviated. Besides, the LCC-S compensated WPT system can operate under zero phase angle (ZPA) condition with low voltage-ampere rating components. A 1.5kW prototype is built and experimental results show that the system efficiency up to 93% can be achieved under full load, which is 2.3% higher than that of conventional WPT system with two stage power conversion.

The pseudo-continuous conduction mode (PCCM) zero-voltage-switching (ZVS) modulation scheme is widely used in the four-switch buck–boost (FSBB) converter to achieve high efficiency and voltage step-up/step-down without modulation mode transition. There are two degrees of modulation freedom in the PCCM ZVS modulation scheme. The previous schemes typically only optimize one of them to reduce root mean square (rms) inductor current, which results in relatively lower efficiency in the condition when the difference between input voltage and output voltage is large. In this article, a multi-frequency PCCM ZVS modulation scheme is proposed for the FSBB converter with wide input and output voltage ranges. By optimizing both of the two degrees of modulation freedom to reduce rms inductor current, the heavy-load efficiency can be effectively improved when the difference between input voltage and output voltage is large. Thus, the overall efficiency of the FSBB converter can be optimized. A 1500-W FSBB prototype with input and output voltage ranges of 200–400V is built to verify the proposed modulation scheme.

Single-stage AC/DC converter with high power factor (PF) usually suffers from significant output voltage ripple at double line frequency. In order to suppress such low-frequency output voltage ripple and maintain high PF, a series compensation circuit (SCC), which generates the same magnitude but 180° phase shifted low-frequency voltage ripple, is connected in series with the output of power factor correction (PFC) converter. In this paper, output impedance model of SCC is established and the relationship between output impedance of SCC and low-frequency output voltage ripple of AC/DC converter is analyzed. Based on the proposed output impedance model, low-frequency output voltage ripple can be evaluated. To further reduce low-frequency output voltage ripple, output impedance shaping method with virtual impedance is presented. The implementation of virtual impedance of SCC with average current mode control (ACMC) is studied. Flyback PFC converter with buck SCC is implemented for the study of the suppression of low-frequency output voltage ripple. A prototype is designed to verify the analysis results.

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.