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Two-stage AC-DC converters are considered as a prominent solution for DC-type electric vehicle (EV) chargers. However, this kind of architecture suffers from high switching losses with large heatsink and DC-link capacitor volume. To relieve this issue, this paper presents a new hybrid modulation for DC-type EV chargers, where a two-phase clamped discontinuous pulse-width-modulation (DPWM) in the front-end circuit is cooperated with the variable frequency triangular-current-mode (TCM) zero voltage switching (ZVS) or its simplified implementation, i.e., boundary-ZVS (B-ZVS) strategy, in the back-end circuit. The former can stop the switching actions in the front-end stage during two-thirds of the grid period, while the AC currents are at their highest values, which can yield to the best switching loss reduction and deliver high power factor operation. Besides, TCM-ZVS or B-ZVS modulations can achieve ZVS turn-on action for all semiconductors during all operating range in the DC-DC stage to further reduce the power losses on the semiconductors. With such characteristics, the proposed strategies can reduce the switching losses of the system to the best extent, and thus allow an enhancement of the system power density by improving the power conversion efficiency. The proposed strategy is described, analyzed, validated, and benchmarked in a 5 kW SMD SiC MOSFET-based two-stage AC-DC converter. A 99% power efficiency can be achieved with the solution implementing the TCM-ZVS strategy at an output voltage of 400 V and rated power. [ABSTRACT FROM AUTHOR]

A nonisolated single-stage on-board charger for electric vehicles has been proposed to increase system efficiency and power density in previous works. However, its ability to achieve high efficiency is limited by variations in the electric utility and battery, especially during the step-down operation. This paper proposes an advanced control algorithm that improves system efficiency in the step-down mode by controlling each switch asymmetrically using a phase-shift control. The proposed algorithm consists of only one controller, which prevents transient states from causing variations in the controller. The algorithm decreases the magnitude and ripple of the inductor current, which improves the charging efficiency by approximately 4.1% over at the 3.7-kW full load that of the conventional algorithm in the step-down mode, and measured total harmonic distortion and power factor are 3.2% and 0.995, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a six-phase current reconstruction scheme for dual traction inverters in hybrid electric vehicles (HEVs) with a single dc-link current sensor. During the phase current reconstruction, one of the inverters is proposed to operate using active vectors, whereas the other inverter operates using nonactive vectors. An advanced phase-shift scheme for all pulsewidth-modulated (PWM) signals based on the sequence of duty cycles is implemented. PWM signals are considered in three types: large, medium, and small duty cycles. Then, the minimum phase-shift scheme is applied to each type of PWM signal to ensure the minimum duration of the active vector for stable current reconstruction. With this proposed phase-shift scheme, the maximum allowable modulation index and dc-link voltage utilization are improved. In addition, the relationship between the minimum required time for stable phase current reconstruction and the maximum allowable modulation index is derived theoretically. The effectiveness of the proposed method is verified by both simulation and experimental results. With this scheme, cost and volume of dual inverters in HEVs are reduced, considering the lower number of current sensors. [ABSTRACT FROM PUBLISHER]