HOW2POWER TODAY

ISSUE: July 2022

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IN THIS ISSUE:

» IC Simplifies Analog Control Of The Totem-Pole PFC Stage

» Designing An Open-Source Power Inverter (Part 5): Kilowatt Inverter Circuit Design

» Electrothermal Models Predict Power MOSFET Performance More Accurately

» Focus On Magnetics:
Transformer Design Pitfalls: Stepup Is Not As Easy As Stepdown

» Special Guest Commentary:
Empowering High-Voltage AC Applications With Monolithic GaN Bidirectional Switches

» New Power Products

» Industry Events

» Other Top Power News

Conference tutorials offer opportunities to expand your power electronics knowledge quickly with the benefit of expert instruction. Often the instructors for these tutorials are academics (university professors) rather than engineers working in industry, because in many cases the latter may not be allowed by their employers to present on advanced tutorial topics for fear of their revealing proprietary information. So the professors, who sometimes also serve as consultants to industry, provide a valuable service in giving tutorials on cutting-edge subjects. Nevertheless, there are engineers in industry for whom giving tutorials is not in conflict with their company’s mission, but rather supportive of it as their instruction somehow involves their company’s products. Engineers making their way to this year’s ECCE conference in Detroit (October 9-13) will find examples of both types of instruction in an expansive series of 24 tutorials on a wide range of design topics such as application of WBG devices, power electronics modeling, control, magnetics, and motor drive design as well as application-focused sessions relating to vehicle electrification and power grids. Naturally, some of these tutorials are relevant to those working in automotive—an application area that always gets its due at ECCE (both power electronics and electric machines) but even moreso this year with the conference being held in Detroit. The topics are too numerous to adequately describe here, so please browse this list of ECCE 2022 tutorial abstracts at your convenience. For those interested in advanced topics, also check out the subjects being tackled in ECCE 2022’s 18 special sessions, in which experts from industry, academia and government will discuss the latest developments in some of the same areas covered in tutorials. However, in this forum the discussions are more forward looking with an eye toward addressing both current and future design challenges.

HOW2POWER EXCLUSIVE DESIGN ARTICLES

IC Simplifies Analog Control Of The Totem-Pole PFC Stage

by Christophe Basso, Future Electronics, Toulouse, France

Although conceived over 25 years ago to regain the precious percent of efficiency lost in the front-end bridge of high-power pre-converters, the totem-pole power factor correction (TPFFC) circuit did not become practical until the introduction of wide-bandgap semiconductors—the SiC and GaN power switches. Since these devices became widely available, TPPFC solutions have become popular and are currently implemented using digital control carried out by a microcontroller. However, analog solutions are now emerging, such as the NCP1680 from onsemi which brings a fully integrated product for operating a borderline conduction mode (BCM) TPPFC. This circuit lends itself well to powering converters up to a level of 300 W for a universal mains application, while incorporating the benefits of higher efficiency and increased power density which the TPPFC supports. Read the article…

Eliminating the need to write code for a
microcontroller, the NCP1680 mixes
analog and digital circuitry to orchestrate
the many variables that need to be
monitored in a TPPFC pre-converter.

This part discusses at length the
design of the inverter stage’s circuit
protection.

Designing An Open-Source Power Inverter (Part 5): Kilowatt Inverter Circuit Design

by Dennis Feucht, Innovatia Laboratories, Cayo, Belize

This series has introduced the design objectives, considerations and a proposed circuit architecture for an open-source power inverter dubbed the Volksinverter. It has also analyzed key design choices such as output waveshape selection, and explored variations on the proposed two-stage inverter architecture. Here in the latest installment, the article delves further into the design of the inverter output stage by presenting a detailed circuit implementation capable of delivering 1.2 kW of output power. This part 5 specifically explains the design and operation of the gate-drivers, ground fault protection and current sensing and overprotection. Read the article…

Electrothermal Models Predict Power MOSFET Performance More Accurately

by Andy Berry, Nexperia, Manchester, U.K.

One of the biggest challenges facing engineers when designing with discrete power MOSFETs is the fact standard simulation models provided by many manufacturers are limited in how well they emulate real-world performance. For example, most standard models can only be used to simulate how a discrete device will behave at a nominal temperature (typically 25°C). In addition, they neglect to include some important device parameters that could provide insight into the electromagnetic compatibility (EMC) performance of a circuit. In this article we explore the limitations of standard models for power MOSFETs by simulating a simple half-bridge circuit typically used in a range of motor control applications. We then demonstrate the improved accuracy that can be obtained by performing the same simulation using an advanced electrothermal model developed by Nexperia. Read the article…

Simulation of double pulse
testing using a standard MOSFET
model produces unrealistic,
excessive voltage overshoot and
ringing.

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

Transformer Design Pitfalls: Stepup Is Not As Easy As Stepdown

by Gregory Mirsky, Design Engineer, Deer Park, Ill.

When designing transformers, engineers often forget that they not only transform one voltage into another but also transform impedance. The apparent input impedance has a component that is the secondary impedance divided by the squared transformation coefficient. This causes certain problems with power transfer at high frequency by means of a stepup transformer. In particular, these problems relate to the impact of the turns ratio and other factors on the input circuit time constant. In this article, we will analyze the relationship between these parameters and demonstrate this relationship with a design example. Read the full article…

Transformer model for analyzing
impact of turns ratio and secondary-side
components on input impedance.

SPECIAL GUEST COMMENTARY

Empowering High-Voltage AC Applications With Monolithic GaN Bidirectional Switches

by Mohamed Imam, Infineon Technologies, Chandler, Ariz.

We don't think of the switches we use in our everyday lives as having a direction: a light switch turns the light on or off, even though it is powered by alternating current (ac). But in the world of semiconductors, most switches are not bidirectional, and this makes many forms of circuitry more complex than they would be if cost-effective bidirectional switches (BDSs) were available. So that’s what we’re working on at Infineon. Read the full story…

  — POWER PRODUCTS IN 3 IMAGES OR LESS

INDUSTRY EVENTS

Workshop Discusses The Latest Trends And Technologies In Vehicle Electrification

by Fred Weber, PSMA Vehicle Electrification Workshop Chair

On Tuesday, September 13 at 9:00 AM CDT and the following Tuesday, September 20, at 9:00 AM CDT, the PSMA Transportation Electronics Committee will offer an extraordinary two-session virtual Vehicle Electrification Workshop which will be focused on the latest technologies and future trends in this area. This workshop will be fine-tuned for any engineer or manager that is involved in vehicle electrification. This includes not only those in the automotive industry, but also those in off-road and heavy-duty industries. Each session will lead off with keynote speakers and end with Q & A and a roundtable discussion. The first session’s keynote will be offered by KIA Motors with a presentation on the “Evolution of the EV Market”.

Read the full story…

Symposium Shares Knowledge On Electrical Transients And Electrical Overstress

The EOS/ESD Association’s annual EOS/ESD Symposium, which will be held September 18-23, 2022, at The Peppermill in Reno, NV, is the premier international event for professionals in industry and academia working in the field of EOS and ESD to meet and learn about the latest technical findings and innovative designs. The EOS/ESD Symposium is a long-standing conference dedicated to the understanding of issues related to electrical transients and electrical overstress, and the application of this knowledge to the solution of problems in consumer, industrial, and automotive applications. This includes electronic components and manufacturing, as well as systems, subsystems, and equipment.

Read the full story…

OTHER TOP POWER NEWS

CPES will again offer the short course “Modeling & Control Design of DC-DC Converters,” August 1- 5 in Blacksburg, Va.

CISSOID has collaborated with NAC Group and Advanced Conversion to offer a compact, integrated three-phase SiC power stack combining a 1200-V SiC Intelligent Power Module from CISSOID and a six-pack low-ESR/ESL dc-link capacitor from Advanced Conversion.