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This paper investigates a Vienna rectifier as a charger for series-connected battery packs. Focusing on carrier-based pulsewidth modulation (CBPWM), the ripple current flowing through the neutral point (NP) results in the voltage oscillation if the loads are resistive. To reduce the ripple of average NP current with mitigated distortion under balanced and unbalanced dc-link voltages conditions, a novel CBPWM with segmented component injection scheme (SCIS) is proposed in this paper. After dc component injection, continuous intervals for optimized component injection and clamping intervals for compensation component injection are identified. Optimized components are calculated originally based on unbalanced factor to make the average NP current zero-size in one switching period. Moreover, unique compensation components generate suitable NP current to shape the sinusoidal input currents according to the circuit analysis. In consequence, the SCIS not only keeps the input current with low-harmonic distortion, but also minimizes the oscillation of dc-link voltage under balanced and unbalanced conditions. In addition, the value of the NP current during the clamping intervals is analyzed under various operating conditions. The effectiveness and the performance of the proposed SCIS are verified by simulation and experiments. [ABSTRACT FROM AUTHOR]

This paper presents a summary of the available single-phase ac–dc topologies used for EV/PHEV, level-1 and -2 on-board charging and for providing reactive power support to the utility grid. It presents the design motives of single-phase on-board chargers in detail and makes a classification of the chargers based on their future vehicle-to-grid usage. The pros and cons of each different ac–dc topology are discussed to shed light on their suitability for reactive power support. This paper also presents and analyzes the differences between charging-only operation and capacitive reactive power operation that results in increased demand from the dc-link capacitor (more charge/discharge cycles and increased second harmonic ripple current). Moreover, battery state of charge is spared from losses during reactive power operation, but converter output power must be limited below its rated power rating to have the same stress on the dc-link capacitor. [ABSTRACT FROM AUTHOR]

AC/DC converters used for charging high-voltage battery banks in electric vehicles from the utility mains, generally, consist of two stages. The first is a power factor correction (PFC) ac/dc boost converter to reduce the input current harmonics injected to the utility grid and convert input ac voltage to an intermediate dc voltage (dc-bus voltage). The second part is an isolated dc/dc converter for providing high-frequency galvanic isolation. This paper presents a novel intelligent control law based on the differential flatness theory to control the input power of the PFC stage which is determined by the charging characteristics of the high-energy battery bank, instead of controlling the intermediate dc-bus voltage at a constant value as done in the conventional controller. Application of the proposed control law to such an ac/dc converter helps improve the dynamic behavior of the input PFC stage compared to the conventional controller and also achieve load adaptive regulation of the intermediate dc-bus voltage. Such load-adaptive dc-bus voltage regulation allows the dc/dc full-bridge converter to operate optimally from no-load to full-load conditions unlike the conventional controller with constant dc-bus voltage which forces the dc/dc full-bridge to operate with very low duty ratios at no-load conditions. Experimental results from a 3-kW ac/dc converter are presented in the paper to validate the proposed control method. The improved converter performance and increased efficiency as compared to the conventional control method proves the superiority of the proposed technique. [ABSTRACT FROM AUTHOR]

In this paper, a high efficiency inductive wireless power transfer system for the on-board chargers of electric vehicles is proposed. In order to improve the power transfer efficiency, the proposed system adopts two additional intermediate coils with resonant capacitors, which increases the effective magnetizing impedance between the transmitter and receiver coils with no ferrites. The resonant tank of the proposed system is designed to operate the converter as a current source and as a voltage source at two different frequencies to implement the constant current (CC) mode charge and constant voltage (CV) charge, respectively. Since the proposed converter operates at a fixed frequency in each mode of charge operation, full soft switching of all the switching devices is possible and the zero phase angle condition can be achieved in both the CC and CV mode operations. A theoretical analysis based on a Thevenin model to come up with a suitable design for the battery charger and its closed-loop controller is presented and its superior performance is demonstrated by experimental results. A 6.6 kW prototype is implemented with a 200 mm air gap to demonstrate the validity of the proposed method. Experimental results show that the dc to dc conversion efficiency of the proposed system is 97.08% at 3.7 kW of output power in the CV mode charge. [ABSTRACT FROM PUBLISHER]

In single-phase ac high-voltage (HV) battery chargers, as the input current is enforced to be varying sinusoidally in phase with the input voltage, the pulsating power at two times of the line frequency will be seen on the dc-link. Bulky capacitor bank or extra active filter (AF) circuits are needed to assimilate this harmonic current, which become a major barrier in terms of power density and cost. Sinusoidal charging method can be applied, while this might affect the charging efficiency and a deep study is still needed to further investigate on the impact to the Lithium-ion battery. An active filter auxiliary power module (AFAPM) based dual-mode dual-voltage charging system for vehicle application has been proposed. The AFAPM converter has two modes: the HV active filtering mode, in which the vehicle is connected to the grid and the converter assimilates the significant second-order harmonic current; and the low-voltage (LV) battery charging mode, in which the vehicle is running and the converter charges the LV battery from HV battery. However, a relay and inductors are still required in that converter to achieve the dual-mode operation. This paper proposes a primary full-integrated AFAPM for electrified vehicle applications with single-phase onboard chargers. The proposed AFAPM converter is composed of a two-phase bidirectional buck converter to work as an AF and a dual-active-bridge to operate as a LV battery charger auxiliary power module (APM). With the proposed converter, only an extra active energy storage capacitor is needed to achieve the active filtering. All the switches and inductors on the primary stage are shared between the AF and APM. Therefore, the use of a bulky capacitor bank or an additional AF circuit is avoided and, thus, the cost, size, and weight of the dual-voltage charging system in the electrified vehicle applications can be reduced. A 720-W prototype has been built to confirm the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

In single-phase onboard chargers for electrified vehicles, second-order harmonic currents and corresponding ripple voltages exist on the dc bus. The low-frequency harmonic current is normally filtered using a bulk film capacitor or an additional active filter (AF) circuit. This presents an obstacle for improving the power density as well as reducing the cost. This paper proposes a simple and effective method that reduces the bulk capacitor in single-phase chargers and alleviates the low-frequency sinusoidal harmonic current in automotive applications. It applies the low-voltage (LV) battery charger auxiliary power module as an AF to filter the low-frequency harmonic currents in the high-voltage (HV) battery charger when the HV battery is charging. Hence, the integrated active filter auxiliary power module (AFAPM)-based dual-voltage charging system can achieve the AF function without extra power switches, heat sinks, and corresponding gate-drive circuits. In addition, the proposed AFAPM converter can obtain an almost unchanged switch rating to achieve 2.4-kW LV battery charging and 6.6-kW HV active filtering functions. Therefore, the proposed method can reduce the cost for the dual-voltage charging system in electrified vehicles. A 1.2-kW proof-of-concept prototype has also been built and experiments show promising results confirming the effectiveness of the proposed concept. [ABSTRACT FROM PUBLISHER]

The first stage of a battery charger in electric vehicles is a power factor correction (PFC) circuit, which creates a second harmonic in the dc link. This harmonic is typically filtered through a bulky dc-link capacitor. In the conventional battery chargers, another dc/dc stage is utilized to regulate the battery current. In this paper, the second harmonic in the dc link is analyzed in detail and a new load current compensation technique is proposed. The proposed technique replaces the second stage dc/dc converter with a bidirectional dc/dc converter connected in parallel with the load, and requires a secondary energy source, i.e., a small-size capacitor. The capacitor injects 180° phase-shifted second harmonic current to the dc link. Thus, the dc-link capacitor can be reduced significantly as it is only sized for high-frequency ripples rather than being sized for low-frequency content. The proposed method is generalized for resistive and battery loads with voltage- and current-source PFC circuits. A 360 W prototype is developed to experimentally verify the proposed technique. A 72 V/10 A·h battery module is charged by filtering an oscillating power of 360 W using a two-quadrant bidirectional dc/dc converter and an UC module, demonstrating a peak charging current of 16 A. [ABSTRACT FROM AUTHOR]

This paper suggests a new electrolytic capacitor-less bi-directional on-board charger for electric vehicle. It has a cascade structure of constant frequency resonant converter for electrical isolation and DCM buck/boost converter for charging/discharging control and input harmonic regulation. Harmonic modulation technique is also proposed to obtain a high power factor and structure change method has been adopted to cope with a wide line voltage condition. Harmonic regulation and charging/discharging control can be accomplished with very simple control algorithm so that high performance controller is not required. Its feasibility has been verified with a 3-kW prototype. [ABSTRACT FROM AUTHOR]