The plenary session and the conference kicked off with a "History and Future of Power Electronics," preamble by Dr. John Kassakian. Kassakian reviewed the conference's origins and 25-year history before describing the rise in importance of today's power-design engineer as they pursue advances in energy harvesting, implement the smart grid and focus on power management and conservation.

Kassakian laid the path for the plenary's next speaker, J.B. Straubel, Tesla's chief technology officer. Straubel captivated the crowd with detailed explanations of the power system of the company's now famous Roadster and how continual improvements in power electronics had greatly improved power density and motor torque making the electric power train possible—and the fully electric vehicle (EV) a reality.

Now capable to reach distances of up to 244 miles one battery charge, the latest power train now features an improved inverter that can deliver higher motor current, an improved motor that can handle more current and torque, and the use of IGBTs to convert and regulate power from the battery.

According to Straubel, the use of IGBTs improved the power train's efficiency and power handling capability while also boosting the output current from 640 to 850 A rms—a 33 percent improvement.

The dangers of solar
While solar panels have the altruistic advantages that come with energy harvesting and relatively few environmental trade-offs, SolarBridge Technologies' Chief Executive Officer Rob Van Dell warned of the unforeseen dangers that come with its installation on rooftops.

Due to the high DC voltage these panels require there lies an inherent fire risk if an "arc fault" occurs. An example was given of fire fighters shutting down a building's but forgetting to shut off the power generated by the panels. Crews have learned that the electrical supply lines for a group of panels can arc and cause fires and they are now trained to take precautions to ensure that the panels are de-energized.

However, solar panels have other, more-insidious disadvantages when implemented in series. In such instances, a low output from any one of the panels in the series can impact the entire system and result in a voltage drop. Consequently, every panel in the series must be matched within 3 percent output to operate effectively.

Van Dell's solutions to this problem included the concept of an AC array implementation , which places the power microinverter immediately on the back of each individual panel and then incorporating filtering techniques such as passive DC bus configurations and electrolytic capacitors.

The increasing use of virtualization and cloud-computing techniques in data applications has resulted in network and storage trending to larger, global architectures, or Mega Data Centers. It was with this in mind that Victor K. Lee, chief technology officer at Emerson Network Power discussed in detail the importance of power efficiency in these data centers and, in particular, how power and cooling architectures can be one of the single-most-important factors when creating a dedicated, power-efficient data center.

According to Lee, cooling is typically the least efficient aspect of any data center, featuring an energy loss of approximately 36 percent of the power put in to function. Lee showed how close-coupled cooling (a combination of air-side economization and evaporative cooling) was used by Emerson to achieve 31 percent improvement in overall power efficiency.

Lee finished by comparing AC to DC power conversion and highlighted the reduction of the power-conversion stage in the DC data center, resulting in an efficiency improvement of 3 to 7 percent over the AC model. Most importantly was the size of the DC center, up to 30 percent smaller than the AC data center. However, the AC data center had one main advantage, a better total cost of ownership and therefore less of a premium.

Other highlights of the plenary session included an update on the state of the art in digital power by Embedded Power Labs Chief Engineer Robert V. White. White spoke of the early hype of the digital power and its promises of reduced costs, increased functionality, adaptive controls and other advantages. While the hype soon subsided, the field has continued to advance. Digital signal processors are now considered inexpensive enough to be considered for power designs and digital signal controllers are becoming a tool of choice.

At APEC, many companies are presenting new advances in digital power technology, such as Intersil's ISL8200M digital power module. Singular devices like this reduce BOM costs by negating the need for passive components like LDOs, octocouplers, etc. while maximizing energy output over a range of differing values. Companies like Intersil, Analog Devices and others have a renewed focus on digital power as the functionality of their devices increase as they embrace this new technology.