ISSUE: October 2009


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From the Editor’s Desk

Debunking Transformer Performance Myths

Ultracapacitors Give Lift to Material Handling

You Too Can Write for How2Power Today

New Power Products

Power Supply Jobs & Technology


From the Editor's Desk

David G. Morrison
Editor, How2Power TODAY       

When a device has been around for many years, ideas about how it works are taken for granted even if those ideas turn out to be false. In electronics, that can true for fairly complex devices like power transistors, which have been around for a few decades. But surprisingly, it can also be true for seemingly simple components such as transformers which have been around in some form for well over a century. Many of this newsletter’s readers have no doubt spent a great deal of time designing these magnetic components for their power supply applications. Yet, as Steve Sandler and Danny Chow explain in their design article, some of the assumptions designers make when working with transformers are wrong. For their efforts in dispelling certain notions about transformer turns ratios and other familiar parameters, the authors will receive How2Power Today’s first “Wake Up and Smell The Coffee Award.” As their prize, each author will receive a $25 gift certificate to Starbucks, which may serve to stimulate more myth-busting articles in the future.


Debunking Transformer Performance Myths

by Steven M. Sandler and Danny Chow, AEi Systems, Los Angeles, California.

There are three common myths regarding transformers, and more generally, magnetic coupling. Surprisingly, these myths concern fundamental concepts in transformer design, and perhaps they’re a source of unexpected results in your design work. One myth concerns how you measure the turns ratio. Another relates to the meaning of leakage inductance. The third myth deals with the role of inductance factor (AL) in calculating transformer inductance. To dispel these myths, the authors conducted a series of experiments on transformers with different winding configurations. Read the full story...


A vector network analyzer is used to measure inductance
and turns ratio of transformer samples.

Ultracaps (EDLCs) reduce the peak current levels
drawn from the battery in electric forklift applications.

Ultracapacitors Give Lift to Material Handling

by Chad Hall, Ioxus, Oneonta, NY

Many battery-powered electric forklifts are used in large refrigerated warehouses. In these sub-freezing environments, traditional batteries have a lower than normal terminal voltage. This loss of voltage reduces a battery’s power output and requires that the users stop to change the batteries at least once during a normal eight-hour shift. Ultracapacitors can help by provide energy storage to support the batteries in lifting loads of 3000 lbs. Ultracaps even enable forklifts to deliver full power output at temperatures as low as 40 degrees below zero. In this article, the author discusses the benefits of deploying ultracapacitors in forklifts and application issues that arise when doing so. Read the full story...

You Too Can Write for How2Power Today

by David G. Morrison, Editor, How2Power Today

Have you ever wanted to submit an article to an electronics publication, but didn’t know where to start? Submitting articles to the How2Power Today newsletter is really quite easy. We accept articles on a wide variety of topics. The main requirement is that the proposed article address an existing design challenge in power conversion, while providing information that may be of practical use to working engineers. Read the full story...

Write for How2Power.


Powerex’s new DIP-IPM family

Intelligent Power Module Sets New Mark for Power Delivery

 Photo: Powerex’s DIP-IPM family includes a model that delivers 75A at 600 V.

 Diagram: Use of new resin improves the thermal impedance of this package by 30%.

 Diagram: DIP-IPMs co-package gate drivers with IGBTs to form highly integrated power stages for three-phase inverter applications.

More details...

Hybrid power amps from Cirrus Logic

A Slew of Improved Specs for Piezoelectric Drivers

 Photo: Two high-voltage, high-speed hybrid power amps from Cirrus Logic deliver higher performance for piezoelectric drivers.

 Graph: The PA107DP power amp achieves a 3000-V/µs slew rate.

 Diagram: The PA107DP drives piezos in medical imaging and ultrasound applications.

More details...


Vishay’s PLAC 100 planar transformer

A User-Configurable Planar Transformer

 Photo: Vishay’s PLAC 100 220-W planar transformer can be adapted to a variety of SMPS designs.

 Diagram: The transformer contains 12 individual windings that users may connect in various configurations.

 Photo: A design kit provides transformer configuration software and the different transformer models.

More details...

Vicor’s 28-V Micro DC-DC Converters

A Smaller Dc-Dc Converter For Military or Commercial Vehicles

 Table: Ratings for Vicor’s 28-V input Micro DC-DC Converters compared to ratings of the larger, Maxi DC-DC converters.

 Photo: The 28-V Micro dc-dc converters offer a smaller packaging format for applications that require 50 W or 100 W.

More details...

Electronic Design & Research’s
4-kW dc-dc converter

Topology Takes Charge Pump To Kilowatt Levels

 Photo: Designed for an electric vehicle application, the
4-kW charge-and-add (C&A) dc-dc converter prototype achieves 87% efficiency and weighs only 10 lbs.

More details...


Some Glimmers Of Hope in Tough Engineering Times

I just read an article analyzing the results of Electronic Design’s latest engineering salary survey. In “Engineers Give Back 2008 Gains In 2009,” Jay McSherry paints an overall bleak picture of the current employment situation for electrical engineers. He cites rising unemployment, falling wages, dissatisfaction among many engineers regarding their compensation, and a sense that there aren’t opportunities elsewhere (at other companies) for better employment.

Bleak stuff. Yet, despite all this, as McSherry writes, “a whopping 84% of engineering professionals still say they would recommend engineering as a career path to a young person looking to choose a profession.” Perhaps, deep down inside, engineers are optimists. Read the full story...


 Balu Balakrishnan, CEO of Power Integrations, who received the 2009 TechAmerica Innovator Award in recognition of the environmental benefits of his company’s EcoSmart technology. This technology reduces standby power consumption in electronic products. press release

 The Formula-Hybrid Team at San Jose State University, one of several collegiate teams building a hybrid-electric race car to participate in the SAE International’s 2010 Formula-Hybrid design competition. website

 The inaugural Energy Conversion Congress & Expo held last month in San Jose. Over 900 attendees from over 40 countries, and 600 technical papers, made this conference a great success. Thanks to all who stopped by to visit with me at the How2Power booth. website