ISSUE: January 2019


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» High-Power Wireless Charging For EVs (Part 1): Understanding The Basics

» Two-Switch Flybacks Outperform LLC Resonant Converters On Most Parameters

» MLCC Shortages—Polymer Electrolytics Can Help

» Focus On Magnetics:
Designing Energy Storing Inductors Properly

» Spotlight On Safety & Compliance:
Roadmap Charts Compliance Trends And Requirements For Power Supplies

» New Power Products

» Industry Events:
CES 2019: A Great And Possibly Growing Forum For Power Developments

» Other Top Power News

From the Editor's Desk

David G. Morrison
Editor, HOW2POWER TODAY       

CES, the first major electronics trade show of the year, describes itself as “the proving ground for transformative tech such as 5G connectivity, artificial intelligence, augmented and virtual reality, smart cities, sports, robotics and more.” The show’s list of product categories and marketplaces drills down into additional application areas that are top of mind at this year’s show including 3D printing, digital money, drones, enterprise solutions, fitness, health and wellness, IoT infrastructure, self-driving technology, smart home, wearables and wireless devices. These topics have been showcased at CES before and should continue to impact the development of power electronics, creating demands for specialized power supply solutions. (For more on this subject, see ”CES 2019: A Great And Possibly Growing Forum For Power Developments” below in the Industry Events section.) There are also new topics getting attention at CES that may have relevance for power electronics engineers. In particular, a conference track on resilience addresses technologies that “even in the face of adversity, keep the world healthy, safe, warm, powered, fed and secure.” While the concept of resilience is familiar to a power supply industry that must continually design to “five nines” and other high reliability standards, CES’ recognition of the need to “keep the world…powered” highlights the likelihood that the broader tech world and the world at large may be recognizing the value of reliability and might even be willing to pay more for it. As technology continues to permeate our lives, there may be no choice. Readers of this issue of the newsletter can ponder the reliability and resilience challenges as they read about high-power wireless charging, two-switch flyback converters, replacement of MLCCs, the design of energy storing inductors, a safety and compliance roadmap and more.


High-Power Wireless Charging For EVs (Part 1): Understanding The Basics

by Patrice Lethellier, WAVE, Salt Lake City, Utah

Charging an electric vehicle (EV) battery through wireless power transfer, also known as wireless charging: why is there interest? It is mainly because the line cord is a liability. Plugging in a line cord 365 times a year becomes tiresome and sometimes you may forget. For a company with a fleet, plugging in a line cord may require a qualified electrician. The cost and reliability of high-voltage, high-current connectors are also issues. This article explains the principles of operation for high-power wireless chargers in the range of 250 kW that are being developed for charging commercial EVs (including buses and trucks) and industrial equipment. The characteristics of power transfer in a wireless charger are compared and contrasted with those of a conductive or wired charger. Read the full story…

The real power transferred by the wireless
charger is the same as that of the
conductive charger. But in the wireless
charger, a much larger reactive power is
also present.

Efficiency comparison of a two-switch
flyback with an LLC resonant half-
bridge and a single-switch flyback.

Two-Switch Flybacks Outperform LLC Resonant Converters On Most Parameters

by Jiri Jirutka, STMicroelectronics, Prague, Czech Republic

While price usually comes first, the other main criteria when designing a power supply are high efficiency, low standby power and high power factor. In terms of efficiency and switching losses, the LLC resonant converter is now preferred over the flyback because it offers the advantage of zero-voltage switching (ZVS). But because of its high circulating current in the resonant circuit, the LLC shows worse efficiency at low load. However, an alternative is emerging thanks to some new design options discussed here. Specifically, the two-switch flyback implemented with a quasi-resonant (QR) PWM controller brings significant improvement in all of the key power supply parameters. In this article, the author demonstrates how new QR resonant PWM controllers and SiC MOSFET-compatible gate drivers are making the two-switch flyback converter a lower cost, higher performance alternative to the LLC resonant converter, especially in cases with high-voltage input. Read the full story…

MLCC Shortages—Polymer Electrolytics Can Help

by Wilmer Companioni, KEMET, Fort Lauderdale, Fla.

The multi-layer ceramic capacitor (MLCC) industry is currently experiencing a significant capacity and supply issue. Manufacturers are putting in capacity, but this takes time to feed through and presents little comfort for manufacturers and engineers dealing with looming line stop situations, and supply chain managers who are having to seek parts from non-preferred sources. At times like this, engineers should explore new options and alternative techniques that don’t necessitate having to go through circuit or product redesigns. Polymer electrolytic capacitors such as Kemet’s KO-CAP series capacitors are one alternative that, given certain conditions, can help. This article discusses the operating conditions under which polymer electrolytics are viable replacements for MLCCs in power supply applications. Read the full story…

Parameters such as total capacitance,
voltage, ESR, frequency and reverse
bias determine whether tantalum-
based polymer electrolytic capacitors
can replace MLCCs in power supply

Sponsored by Payton Planar Magnetics
A monthly column presenting information on power magnetics design, products, or related technology

Designing Energy Storing Inductors Properly

by Gregory Mirsky, Continental Automotive Systems, Deer Park, Ill.

This article attempts to show that when designing an energy-storing inductor, one should consider not just the current ripple in the coil and filter capacitors but also the dc biasing current and power that the inductor must store and release. Engineers usually overlook the dc bias and do not link the inductor’s physical size with the required power. Instead, they focus on the desired current ripple, obtaining a value for the core’s physical size from the winding size. After deriving inductor design equations that account for dc bias and the amount of power to be stored, use of the equations is demonstrated with a boost inductor design example. This article may be useful for those who design diverse types of power converters, filters subject to dc biasing, solenoids and other electromagnetic components such as electromagnetic accelerators and weapons. Read the full story…

Sponsored by Power Integrations
A monthly column discussing standards and regulatory requirements affecting power electronics

Roadmap Charts Compliance Trends And Requirements For Power Supplies

By Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

The Power Sources Manufacturers Association (PSMA) devotes a section of its Power Technology Roadmap (PTR) to reporting on relevant trends in power supply safety and compliance. For those unfamiliar with the PTR, it is a document published every two years “to provide a consolidated outlook of trends in power conversion technology for the next two to five years.” In the latest version of the roadmap, PTR 2019, which is due to be released at APEC, the section on Safety & Compliance describes how power supply compliance has become more challenging since the last PTR was published. Although certain requirements such as those for safety and EMC, have always been in conflict, it has become harder to strike the necessary balance in power supply development as both the safety and the EMC requirements become more stringent. There are also more stringent environmental requirements coming from RoHS, WEEE and conflict material legislation. Read the full story…

The Power Technology Roadmap
includes the viewpoints of the
product certification organizations.


Energous’ DA2223 four-port
RF-to-dc wireless power chip.

Receiver Chip Enables Wireless Charging In Smaller Devices

 Photo: A complete WattUp wireless power receiver can be realized using a single 1.7-mm x 1.4-mm x <0.5-mm DA2223 IC coupled with a matching circuit made from two standard discrete components and a tiny 2-mm x 3-mm antenna, which itself can be formed using simple printed circuit board tracking. Such a small form factor makes it well suited for use in small electronic devices where a coil-based wireless charging system is not practical.

See the full story…

Power Integrations’ SCALE-2
2SP0430T2XX plug-and-play gate drivers.

Plug-And-Play IGBT Gate Drivers Are Ruggedized For Renewable Energy And Other Applications

 Photo: The plug-and-play gate driver boards are designed for use with Infineon’s PrimePACK3+ and Fuji-equivalent IGBT modules for two-level and three-level applications, providing reinforced isolation for 1200-V and 1700-V IGBT modules and meeting standards such as IEC60664-1, IEC61800-5-1, PD2 and PD3.

 Diagram: Members of the 2SP0430T2XX family integrate safety features such as UVLO and short-circuit protection plus the new dynamic advanced active clamping. All models are conformally coated to protect the boards against harsh environments.

See the full story…

Renesas' R7F0E embedded controller.

Energy-Harvesting Embedded Controller May Eliminate Batteries In IoT Devices

 Drawing: With its extremely low current levels, the R7F0E enables system manufacturers to completely eliminate the need for batteries in some of their products by harvesting ambient energy sources. An Energy Harvest Controller function enables direct connection to different types of ambient energy sources such as solar, vibration, or piezoelectric.

 Diagram: This embedded controller is fabricated in SOTB, an advanced low-power process technology that is said to break the usual tradeoff between getting either low active current OR low standby current consumption.

See the full story…

Aimtec's AM20CWR-ZK 20-W dc-dc

Railway-Grade DC-DC Converters Tout Value, Wide Operating Ranges

 Table: The 20-W dc-dc converter series includes single-output and dual-output models with operation from 13 to 70 V or 42 to 176 V.

 Photo: Housed in 1-in. x 1-in. packages, these dc-dc converters for railway and industrial applications are said to offer much greater cost effectiveness due to material normalization and production automation, which also lead to improved reliability and performance.

See the full story…


CES 2019: A Great And Possibly Growing Forum For Power Developments

by David G. Morrison, Editor and Kevin Parmenter, Contributor,

With its thousands of exhibits, demo suites and meeting rooms, CES 2019 provided insights into developments and trends in many areas of electronics including power electronics. All of the products being showcased need power supplies in some form. In some cases, such as autonomous vehicles, power electronics is an enabling technology since most of these cutting edge products are electric vehicles. This year Kevin and I toured a few of the exhibition halls at CES and met with representatives of power semiconductor companies in their suites. We not only saw a wide array of end products that are driving demands for high-performance or application-specific power solutions, we also saw many power converter reference designs and product examples using advanced power ICs, power semiconductors, and power modules. Read the full story…


This year, PSMA and PELS are again co-sponsoring two pre-APEC workshops, “The Impact of Wideband Technologies on Application of Capacitors - A Deep Dive on Capacitor Technology” and “Power Magnetics @ High Frequency” at APEC 2019.

Distributech is one of the largest conference and exhibition events for the power distribution industry. This year, the FREEDM Systems Center will be exhibiting at the event to show its work in modernizing the electric grid.

Professor Ćuk will present his masterclass, “Power Electronics: 50 Years in 4 days!” March 25-28, 2019 at UC Irvine, right after the APEC 2019 conference in Anaheim. For more information and to register, see the TESLAco website.