Experimental evaluation of hybrid cycloconverters

Power converters consisting of naturally commutated thyristors such as cycloconverters and current source inverters were the first used in driving electrical motors with variable speed but now due to their inferior performance compared to forced commutated converters, their use is restricted in the high voltage/high power range where the performance and cost of forced commutated switching devices is not competitive yet. Hybrid cycloconverters proposed recently improve the performance of cycloconverters by adding an auxiliary forced commutated inverter with reduced installed power that enhances the control over the circulating current and improves the quality of the output voltage. This paper evaluates the performance of a few standard and hybrid cycloconverter arrangements using simulation and experimental results

Achieving the desired transformer leakage inductance necessary in DC-DC converters for energy storage applications

This paper presents a cost effective winding design and evaluation of a medium frequency isolation transformer typically used in bidirectional isolated DC/DC converters. Since leakage inductance and winding resistance of a high frequency transformer are interdependent, any attempt to increase the leakage inductance by adjusting the winding arrangement increases the resistance as well and impacts the efficiency. This paper proposes the use of flux diverter caps made of a relatively small amount of ferrite material to get the desired value of inductance whilst maintaining the losses in the windings at reasonable levels. The proposal is experimentally evaluated on a 5kW prototype

Efficiency evaluation of a novel supercapattery stack with a power electronic interface for energy storage systems

The increase of renewable energy generation seen as the only way to ensure clean and sustainable development, is under scrutiny due to its intermittent nature and an insufficient development of com-plementary technologies such as electrical energy storage. There are quite a few energy storage devices available such as super/ultracapacitors that can address the high specific power applications compared to batteries, but have quite large size for same energy installed. Batteries on the other hand have much higher specific energy but cannot accommodate that easily the requirement to deliver quickly high power. This paper reports on the evaluation of a newly developed device, the supercapattery, that is a single device in which the core material is chemically engineered carbon nanotubes that can store similar amount of energy as a battery but release it faster

Efficiency evaluation of a novel supercapattery stack with a power electronic interface for energy storage systems

The increase of renewable energy generation seen as the only way to ensure clean and sustainable development, is under scrutiny due to its intermittent nature and an insufficient development of com-plementary technologies such as electrical energy storage. There are quite a few energy storage devices available such as super/ultracapacitors that can address the high specific power applications compared to batteries, but have quite large size for same energy installed. Batteries on the other hand have much higher specific energy but cannot accommodate that easily the requirement to deliver quickly high power. This paper reports on the evaluation of a newly developed device, the supercapattery, that is a single device in which the core material is chemically engineered carbon nanotubes that can store similar amount of energy as a battery but release it faster

Experimental evaluation and efficiency optimisation of a grid-connected converter for household energy storage applications

This paper presents the design and the experimental evaluation of a power converter for energy storage applications suitable for household installation or to facilitate distributed energy storage capability within a local/community low-voltage grid. The technology to build the power converter is a common / low cost one in order to make it affordable which was expected to limit the overall efficiency of the energy storage system. This is why an investigation into power losses at component level followed by an efficiency optimisation procedure is developed which is confirmed by actual power loss measurements. The experimental evaluation includes also the assessment of the AC grid current quality and transient performance

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented

Common mode voltage cancellation in a buck-type active front-end rectifier topology

AC/AC power conversion is widely used to feed AC loads with a variable voltage and/or a variable frequency from a constant voltage constant frequency power grid or to connect critical loads to an unreliable power supply while delivering a very balanced and accurate sinusoidal voltage system of constant amplitude and frequency. The load specifications will clearly impose the requirements for the inverter stage of the power converter, while wider ranges of choices are available for the rectifier. This paper investigates the utilization of a buck-type current source rectifier as the active front-end stage of an AC/AC converter for applications that require an adjustable DC-link voltage as well as elimination of the low-frequency common mode voltage. The proposed solution is to utilize a combination of two or more zero current vectors in the Space Vector Modulation (SVM) technique for Current Sources Rectifiers (CSR)