Modular Self-Balancing Battery Charger Concept for Cost-Effective Power-Assist Wheelchairs

Abstract

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.

Modular Battery Charger for Light Electric Vehicles

“…The modular SEPIC charger was designed for f min = 30 kHz, f max = 120 kHz, and cell power P cell = 100 W [32]. According to the design specifications, the dimensions of the battery charger printed circuit board (PCB) are limited to 230 × 145 mm.…”

“…Present study focus is on the further development of the interleaved SEPIC concept recently proposed as a candidate topology for the battery charger of power-assist wheelchairs [32]. According to the specification, the charger is stored in a compartment under one of the armrests.…”

“…Two SEPIC cells connected in parallel and operating with a 180 • phase shift can provide continuous input current i in , since in this case, it will be formed by the sum of currents in the two cells i cell1 and i cell2 (see Figure 3a). However, increased duration of DCM results in a more distorted input current [32]; therefore, it has to be minimised and the converter should preferably operate close to the boundary conduction mode (BCM).…”

“…Therefore, the third interval with zero input current has a varying interval of t 0 , which is inversely proportional to the input voltage U in . Assuming the constant pulse width γ·T [32], the optimal operating mode can be achieved with BCM provided at the maximum input voltage U in_max and DCM at lower U in values, as depicted in Figure 3a.…”

Combined Power Supply System Trolley and Economic Benefits From Its Use

“…Copyright (c) 2019 Губка Є. О., Вербицький Є. В. Високовольтний акумулятор розрахований на напругу 600 В і слугує для живлення бортової апаратури та тягової установки тролейбуса у випадку зникнення напруги контактної мережі. Паралельно до акумулятора встановлена батарея суперконденсаторів, енергія якої може слугувати для підзарядки акумулятора в режимі автономного ходу тролейбуса [7][8][9][10]. Система керування призначена для керування перетворювачем напруги та зарядними пристроями акумулятора і батареї суперконденсаторів.…”