Bruce Carsten: Lifetime Achievement Award Winner

Sep 1, 2006 12:00 PM
By David Morrison, Editor, Power Electronics Technology

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Power-supply designer, researcher, consultant, instructor and visionary. All of these terms apply when describing Bruce Carsten and the work he has done to advance the state of the art in power electronics over the past 38 years. His accomplishments in switchmode power-supply design provide a roadmap of the progress made by the field as a whole. As he pushed the state of the art in his power-supply designs, Carsten helped lead the migration to higher switching frequencies, applying innovative circuit-design techniques and architectures, and developing novel analysis tools for design.

Among his many achievements, Carsten pioneered the use of constant-frequency peak-current-mode control in the early 1970s; developed the now ubiquitous active-clamp reset technique in single-ended forward converters in 1978 (see the “Exploiting Active Clamp Reset” subhead below); built what may have been the first hot-swappable power modules in 1980; and designed what’s claimed as the first commercially viable switchmode telecom rectifier in 1982, in which he applied multiphase switching in a dc-dc converter years before it became mainstream in voltage regulator modules (VRMs). Carsten is also highly regarded for advancing the design of high-frequency magnetics. One notable accomplishment in this area is his creation of a procedure for calculating winding eddy current losses for nonsinusoidal drive currents.

Many of Carsten’s designs anticipated the trends that have shaped the power-supply industry over the last 25 years. At times, he was a bit too far ahead of the curve, addressing future challenges that others in the industry failed to recognize. Anticipating the eventual migration of CMOS logic from 5 V to lower supply voltages, Carsten demonstrated a 48-V to 2-V dc-dc converter at a power conference in 1984. But as Carsten relates, this development and his related conference paper were met with “resounding apathy.” Ultimately, however, low-voltage logic arrived and created demand for distributed power as Carsten predicted in his paper (see the “Looking Ahead, But Too Far” subhead below).

While explaining some of the factors underlying his work, Carsten describes himself as skeptical, intellectually curious and willing to challenge conventional wisdom. These traits are evidenced in the story of the 2-V power converter and in his accounts of other work experiences. Carsten’s desire to take charge of his designs is another factor. In his early work as an engineer at smaller companies, Carsten found himself responsible for all aspects of design, development and even customer support. He realized that if he rushed a design into production prematurely, it could lead to power-supply failures in the field, which he would be called on to fix. Carsten’s response to this situation was, “If I’m going to have the responsibility for a project, I’m going to have the authority.”

Speaking of his early years as an engineer working in the industry, Carsten relates the difficulty of developing new technologies in a production environment, while trying to get the design right the first time.
“I think I was largely successful,” says Carsten,” but all I got were complaints about how long it took me to design something. When I pointed out that my products passed production test with the least trouble, had the highest profit margin, the longest product lifetime and a warranty return rate about 3% of the company average, the reply was, ‘That’s nice, but can’t you design it faster?’”

The desire to do the job right and have the authority to do so ultimately led Carsten to abandon production design and employment as a staff engineer in the early 1980s for a career as a design consultant. In spite of this change in his employment, he continued to play a role in the industry at large. Through his writings and his extensive participation in various power electronics conferences, Carsten has been an important team member in the effort to educate fellow engineers and support the advancement of power electronics technology. Over the years, Carsten has authored several influential conference papers and magazine articles, led numerous design tutorials in many countries, served on conference advisory boards and chaired conferences.

Beyond Carsten’s activities in the field of power electronics, over the years he has devoted some of his energies to a rather diverse set of interests ranging from space, astrophysics, math and biology, to woodworking, cars and motorcycles. These varied interests reflect a boundless curiosity and a philosophy that underlies much of Carsten’s work in the power electronics field. As Carsten comments, “If you really want to be innovative and creative, you have to cast your awareness broadly, not look at your narrow field.”

Looking over his body of work, it appears that Carsten’s broad awareness of developments in the electronics field helped him to adapt concepts from other areas to the requirements in power electronics. Furthermore, Carsten often conceived of a novel design idea while working on one project, only to apply the technique to full advantage years later in another design.

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