A Battery Charging System & Appended Zcs (Pwm) Resonant Converter Dc-Dc Buck: Technique for Battery Charger to Yield Efficient Performance in Charging Shaping

ABSTRACT

This paper presents technique for battery charger to achieve efficient performance in charging shaping, minimum low switching losses and reduction in circuit volume .The operation of circuit charger is switched with the technique of zero-current-switching, resonant components and append the topology of dc-dc buck. The proposed novel dc-dc battery charger has advantages with the simplicity, low cost, high efficiency and with the behaviour of easy control under the ZCS condition accordingly reducing the switching losses. The detailed study of operating principle and design consideration is performed. A short survey of battery charging system, capacity demand & its topologies is also presented. In order to compute LC resonant pair values in conventional converter, the method of characteristic curve is used and electric function equations are derived from the prototype configuration. The efficient performance of charging shaping is confirmed through the practical examines and verification of the results is revealed by the MATLAB simulation. The efficiency is ensured about 89% which is substantially considered being satisfactory performance as achieved in this paper.

KEYWORDS

ZCS, PWM Resonant Converter, dc-dc Buck, Battery Charger

1. INTRODUCTION

In recent years, with the enhancement of power electronics technology and control strategies in power electronics devices coupled with the increasing demand of high efficiency in battery charger system has invoked enormous attention from the research scholars around the world. Battery charger system technology is currently being incorporated in urban industrial areas to maintain with these demands lot of work is on towards. Therefore, many battery chargers with different ratings and functionalities are being developed for high output efficiency since few years. The battery charger usually works to globalize the energy saving and to serve in fast transportation systems. The use of battery charger brings convince life solution during the traveling from urban to rural areas. Many techniques were fetched out by the scientists since battery charger device was developed for renewable energy generation, electronic communication power supplies, electric vehicles, UPS or an uninterruptible power supplies, PV systems and portable electronics products. Many charging methods have been developed to improve the battery charger efficiency in the last few decades. In order to achieving high efficiency in battery charger, append the traditional battery charger with the technique of ZCS ( Zero-Current- Switching) resonant buck topology which delivered the efficient performance in charging shaping[11-12-13-14].

This work looks at the issues which associates ZCS PWM (Zero-Current-Switching Pulse width Modulation) converter, buck topology with the battery charger. This paper develops a novel high- efficiency battery charger with ZCS PWM buck topology which has simple circuit structure, low switching losses, easy control and high charging efficiencies [1-3]. Zero Current Switching resonant buck converter is analyzed and mode of operation is also studied. Various waveforms & charging curve period were noted down during the piratical examine using MATLAB software. The curve of charging efficiency during the charging period shows 89% charging output efficiency of novel proposed prototype.

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Fig.1 Block Diagram for the Proposed Novel Battery Charger

2. BATTERY CHARGERING SYSTEM & CAPACITY DEMAND

Today’s most modern electrical appliances receive their power directly right away the utility grid. Many devices are being developed everyday which requires electrical power from the batteries in order to achieve large mobility and greater convenience.

The battery charger system utilizes the battery by working to recharge the battery when its energy has been drained. The uses rechargeable batteries include everything from low-power cell phones to high-power industrial fork lifts, and other construction equipment. Many of these products are used everyday around-the-clock commonly in offices, schools, and universities, urban and civilian areas [8-9]. In fig. 2 shows that the Battery Capacities of Various Battery-Powered Devices which are used in different rate of watt per hours level in cell phones, laptops, power tools, forklifts and golf crafts etc.¹⁰.

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Fig.2 Battery Capacities of Various Battery-Powered Devices

A battery charger system is a system which uses energy drawn from the grid, stores it in an electric battery, and releases it to power device. While engineers are used modern techniques to usually design the battery charger systems, which maximize the energy efficiency of their devices to make certain long functioning & operation time between charging; however they often neglect how much energy is used in the conversion process of ac electrical power into dc electrical power stored in the battery from the utility grid.

Apparently, energy savings can be possible if the conversion losses are reduced which associated with the charging batteries in battery-powered products & output voltage can be controlled via switching frequency. We can achieve these savings using different techniques including battery charger topology that is readily available today and is being employed in existing products. The same technique and topology is discussed in this paper which increases the efficient performance in charging shaping of novel battery charger.

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Fig.3Structure of a multi- piece battery charger system. The efficiency calculation is made over a 24 hour charge and maintenance period and a 0.2C discharge for the battery. (Prepared for California Energy Commission Contract by EPRI Solution Ltd.,)[10].

3. METHODS OF BATTERY CHARGING SYSTEM & ITS TOPOLOGIES

Methods of efficiency improvements in battery charger systems in use today have substantially lower possibilities due to a lack of cognitive skills in the charger and battery which commonly consume more electricity than the product they power. The energy savings are achieved in millions of battery charger systems that are presently in operation worldwide by reducing inefficiencies in charger and battery. Battery charger systems work in three modes of operation. In charge mode of operation, the battery is accumulating the charge while the maintenance mode of operation occurs when battery is fully charged and charger is only started to supply energy to undermine the natural discharge. No-battery mode of operation shows that the battery has been physically disconnected from the charger [8-9].

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Fig.4 SwitchModeBatteryChargerPowerVisibility

There are lots of methods which are recognized to achieve the higher efficiency in battery charger systems, including:

- Higher voltage systems
- Switch mode power supplies
- Synchronous rectification
- Improved semiconductor switches
- Lithium-ion batteries
- Charge and discharge at lower current rate
- Off-grid charger when no battery is present.

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TABLE: 1 Efficiency improvements in charger topologies

Table.1 show that the efficiencies of normal and improved range are measured less than 15%, comparable systems with overall efficiencies of 65% or greater are technically feasible in charger topologies for battery charger system. The linear and switch mode chargers are analogous to linear and switch mode power supplies with the exception that the charger topologies also incorporate charge control circuitry on their outputs. Most multi- or single-piece chargers are either linear or switch mode chargers. These two categories are found commonly in consumer applications, particularly in the residential public sector. Ferro-resonant and SCR(silicon controlled rectifier) battery chargers form a large percentage of the chargers utilized in developed industrial applications[10]. This paper provides basic idea about the method of use of switch mode power supplies such as dc-dc converters are considered as they can achieve higher efficiency in battery charger scheme.