A novel single-switch single-stage high power factor LED driver is proposed by integrating a flyback converter, a buck–boost converter and a current balance circuit. Only an active switch and a corresponding control circuit are used. The LED power can be adjusted by the control scheme of pulse–width modulation (PWM). The flyback converter performs the function of power factor correction (PFC), which is operated at discontinuous-current mode (DCM) to achieve unity power factor and low total current harmonic distortion (THDi). The buck–boost converter regulates the dc-link voltage to obtain smooth dc voltage for the LED. The current–balance circuit applies the principle of ampere-second balance of capacitors to obtain equal current in each LED string. The steady-state analyses for different operation modes is provided, and the mathematical equations for designing component parameters are conducted. Finally, a 90-W prototype circuit with three LED strings was built and tested. Experimental results show that the current in each LED string is indeed consistent. High power factor and low THDi can be achieved. LED power is regulated from 100% to 25% rated power. Satisfactory performance has proved the feasibility of this circuit.

In this study, a bidirectional CL³C full-bridge resonant converter was developed using a bidirectional active bridge converter as the main framework to improve conventional LLC resonant converters. A resonant inductor and resonant capacitor were installed at the secondary side of the developed resonant converter. The bidirectional operation of this converter enables zero-voltage switching at the supply-side power switch and zero-current switching at the load side. The aforementioned phenomena enhance the overall circuit efficiency and enable the resonant tank voltage to be increased in the reverse mode, which cannot be achieved with conventional bidirectional LLC resonant converters. The electrical equipment isolation function provided by a transformer made electricity usage safer, and digital control technology was adopted to control electrical energy conversion and simulate bidirectional energy conversion. Specifically, the experiment and simulation emulated how the developed converter enables energy transmission from a DC grid to a battery energy storage system through constant current–constant voltage charging and energy transmission from a battery energy storage system to a DC grid through constant power discharging.

This study proposed an isolated three-port bidirectional resonant converter that combines 2C3L and 2C2L resonant circuits for application in power dispatching. The proposed converter improves the bidirectional power dispatch capabilities of conventional three-port converters and utilizes different resonant converters to complete the energy charge–discharge through ports of different voltage levels. By modulating the frequency alone, bidirectional power regulation and electrical isolation were achieved among the three ports with different voltage levels. The converter involves the use of resonance techniques to enable the power switch to perform soft switching during bidirectional power transmissions, reducing switching loss and electromagnetic interference. The system control of the circuit was a Texas Instruments TMS320F28335 microcontroller. By simulating a DC grid port with a fixed voltage of 400 V, a vehicle battery port with a variable voltage of 280–403 V, and a battery charging port with a variable voltage of 180–213 V, an experimental platform with a rated output of 3 kW was built to determine the accuracy of the proposed theoretical analysis and design method.

An isolated type bidirectional resonant converter is presented in this paper. Using a dual active bridge as the main topology and integrating symmetric resonant mechanism, the developed converter features an isolated type bidirectional resonant converter with bidirectional power conversion and electrical isolation capabilities to ensure working security and stability. The application of a symmetric resonant scheme enables the control range of input and output voltages to be widened and achieves soft switching during bidirectional power conversion. A converter design process covering all the bases is exhibited in this work. With the digital signal processor (DSP) TMS320F28335 being employed as the control core, the developed isolated bidirectional resonant converter can effectively handle the power conversion between the simulated 400 V DC grid and the energy storage battery ranging from 280 to 403 V. Based on a 1 kW capacity design, the test data reveal that the forward conversion efficiency from grid to battery can reach 93.25%, and the reverse conversion efficiency from battery to grid is as high as 94.60%.

This paper presents a single-stage three-port isolated power converter that enables energy conversion among a renewable energy port, a battery energy storage port, and a DC grid port. The proposed converter integrates an interleaved synchronous rectifier boost circuit and a bidirectional full-bridge circuit into a single-stage architecture, which features four power conversion modes, allowing energy adjustment for both the renewable energy and the battery storage energy ports when power is supplied by the renewable energy port. It also features bidirectional functionality that allows the battery storage energy port to provide energy storage through the DC grid port, thereby providing uninterrupted power supply functionality. The converter uses four power switches and two inductors to boost and convert energy from the renewable energy port to the battery storage energy port or to the DC grid port through the bidirectional full-bridge circuit. The converter is also capable of 1 kW power energy conversion by utilizing an adjustable duty cycle with a fixed frequency of 100 kHz and phase-shift control through a built-in pulse width modulation control module of a TMS320F28 series digital signal processor. According to the experimental results, the converter developed in this study can achieve a conversion efficiency of up to 94%.

Due to concerns with air pollution and climate change, governments and transport operators around the world have engaged in transforming their fossil-fueled vehicles into electric vehicles (EVs). It is essential to build a model for the electrifying process to minimize the operation costs. This paper presents a systematic analytical approach for the electrification of a fire ambulance service station. This approach begins with the selection of suitable EVs to replace the current service vehicles. Subsequently, an in-depth analysis is conducted to determine the practical utilization of EVs at the station. The model proposes two charging strategies: immediate charging upon an EVs’ return and smart charging. Based on the chosen EVs and charging strategies, a comprehensive assessment of the load profiles for the planned EV charging station is performed. In accordance with the load profiles, a mathematical model to minimize the infrastructure and operation costs of the charging station is proposed. Various pricing schemes are compared to identify the most efficient pricing scheme for the charging station, and economic analyses of the EVs and traditional ambulance vehicles are proposed in this paper. The test results indicate that the progressive pricing scheme is well suited for immediate charging strategies, whereas smart charging should opt for the time-of-use pricing scheme. Selecting the appropriate pricing scheme has the potential to significantly reduce electric energy costs.