This paper presents an isolated single-stage on-board electric vehicle charger without an intermediate DC-link. Based on an isolated current-source topology, the converter features soft-switching in semiconductors regardless of load variation for the full AC line voltage range. Moreover, it requires no external snubber or clamp circuits. The power factor correction and voltage regulation are provided by a relatively simple phase shift modulation, while the amount of circulating energy is kept at minimum. The charger is distinguished by its efficiency characteristic – the maximum is achieved in the constant power charging mode. The control method, component stresses, and design constraints of the topology are analyzed. The concept is verified using a 3 kW experimental SiC-based prototype, which reaches a peak efficiency of 96.4%. Moreover, the charger has demonstrated efficiencies above 95% with the THD of 4.1% when operating in constant power mode at the maximal power.

This paper presents a novel converterconcept of the off-board electric vehicle (EV) charging, which is based on an unfolding rectification approach where the three-phase Vienna rectifier-based unfolder (VRU) is followed by two identical isolated current-source converter (CSC) modules in input-series output-parallel configuration. The VRU operates at low frequency and thus features negligible switching losses, while the CSCs are responsible for the synthesis of the high-quality sinusoidal grid current waveforms and output voltage regulation. The proposed configuration features two time-varying soft DC-links, thus no bulky electrolytic capacitors are required. Input inductors of the CSCs limit the input current ripple, eliminating the need for separate grid filter inductors. Another notable advantage lies in the simplicity of the control system. Each CSC operates at a fixed frequency and provides the required current wave-shaping using only a single independent control variable, while no high-frequency synchronization between the two modules is required. The proposed configuration features a modular structure and was verified with a scaled 5 kW experimental prototype based on two identical 2.5 kW dc-dc modules and a common unfolding stage. During the experiments, the system provided power factor above 0.97 and THD below 5%. At rated power, the maximal efficiency of 94.8% was obtained.

In this paper the concept of wide input voltage range photovoltaic microconverter with post-fault operation capability is presented. This microconverter could remain operational in the case of short- or open-circuit failure of any switch of its front-end inverter. When the fault occurs, the control system automatically identifies the fault and applies the special post-fault modulation sequence thus keeping the functionality of the microconverter unchanged. The research findings are validated by the help of a 350 W experimental prototype specially developed for integration of silicon PV modules into the residential DC nanogrids with the nominal voltage of 350 V. Paper explains the multi-mode operation principle and fault identification routine. It presents the experimental efficiencies and evaluates the maximum power point tracking performance of the microconverter prior and after the short-circuit fault of an upper switch of the inverter. The daily energy yield test conducted for both cases has confirmed that the proposed approach can extend the service life of PV microconverters with a moderate impact on their performance.

Rapid developments in energy storage and conversion technologies have led to the proliferation of low- and medium-power electric vehicles. Their regular operation typically requires an on-board battery charger that features small dimensions, high efficiency and power quality. This paper analyses an interleaved step-down single-ended primary-inductor converter (SEPIC) operating in the discontinuous conduction mode (DCM) for charging of battery-powered light electric vehicles such as an electric wheelchair. The required characteristics are achieved thanks to favourable arrangement of the inductors in the circuit: the input inductor is used for power factor correction (PFC) without additional elements, while the other inductor is used to provide galvanic isolation and required voltage conversion ratio. A modular interleaved structure of the converter helps to implement low-profile converter design with standard components, distribute the power losses and improve the performance. An optimal number of converter cells was estimated. The converter uses a simple control algorithm for constant current and constant voltage charging modes. To reduce the energy losses, synchronous rectification along with a common regenerative snubber circuit was implemented. The proposed charger concept was verified with a developed 230 VAC to 29.4 VDC experimental prototype that has proved its effectiveness.

The paper deals with a power charger capable of quick simultaneous charging of several unevenly discharged batteries. The charger is designed for use in conjunction with a recently developed power-assist wheelchair composed of two armrest modules associated with wheels—each with its own motor, driver and battery. Uneven discharge of the batteries is very possible in this application. Taking into account the charging power and energy comparable with the most powerful household electrical devices, the refreshing of these batteries and integration of the entire power supply chain into the household grid become a topical and challenging task. Solving of this task requires a special charger that has several channels and can unevenly apply charging power to these channels. At the same time, the charger must not generate current harmonics or reactive power, must operate with good efficiency and satisfy size constraints. In the given research, a configuration of several interleaved isolated single-ended primary-inductor converters is studied. The synthesized mathematical model of the proposed charger provides data about its static and dynamic characteristics while its experimental investigation focuses on operation details (power losses, control features etc.). The obtained results prove that the proposed concept complies with the above-mentioned requirements and can be applied in the discussed application.

Ефективне використання гібридного ємнісного накопичувача енергії джерела живлення для контактного мікрозварювання