HOW2POWER TODAY

ISSUE: May 2026

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IN THIS ISSUE:

» Fast AC Line Dropout Detection Can Enhance AC-DC PSU And System Performance

» Motor Control For Designers (Part 7): Quasistatic And Dynamic PMS Motor Models

» Redefining Q_SW To Obtain Accurate Switching Loss Estimates In RESURF-Based MOSFETs

» Focus On Magnetics:
Inductor Analytical Model And Its Inductance Dependence On Current

» Industry Event: Coiltech North America

» Power Products

» Industry Events: OCP Canada Tech Day & PCIM Asia

» Other Top Power News

From my vantage point as an editor, I hear about many sources of inspiration for the contributed technical articles that come my way. Sometimes the writer has a novel idea for improving performance of a circuit or system in pursuit of well understood industry needs or trends. In other cases, the author discovers a method for improving or simplifying the way a familiar circuit is designed. Many articles on modeling fall into this category. But, it’s not always a whole circuit in question—it can be just a particular component design. In this case, the inspiration could be the recognition of an inadequacy in existing models. This applies to Gregory Mirsky’s latest article on modeling inductors. His article was inspired by the tendency he saw among engineering authors to treat inductance as a constant when writing about power supply design and simulation, even though the variation of inductance with current can be an important factor in inductor design and selection. While there is the capability within LTspice to incorporate the current influence within inductor models—and there’s a video online that can help with this task—the author recognized that an analytical model capable of determining inductance with current dependence from data sheet parameters could really be useful. Read on to see how he derives this model and applies it in a design example. Meanwhile, in his motor control article, Dennis Feucht extends his previous electromechanical model for PMS motors to provide a more complete dynamic model, and in another feature, Orion Kress-Sanfilippo explains how to obtain accurate switching loss calculations with the new RESURF-based MOSFETs. Finally, Viktor Vogman explains how fast analog ac dropout detection enables a variety of performance benefits in server power supplies. This issue also brings news on a host of recently introduced power products, three upcoming industry events and more.

HOW2POWER EXCLUSIVE DESIGN ARTICLES

Fast AC Line Dropout Detection Can Enhance AC-DC PSU And System Performance

by Viktor Vogman, Olympia, Wash.

This article examines the implementation of fast analog ac dropout detection and discusses the associated benefits for server PSUs and the IT systems they power. We begin by explaining the operation of the basic fast ac fault detection technique. We then discuss how the ac sag detection time can be shortened and how feeding the ac fault signal to the IT system allows for the usage of fast-blow fuses, while reducing their potential tripping. We then show how ac dropout detection enables the use of smaller bulk filter capacitors or, alternatively, achieves higher PSU efficiency with existing capacitor sizes. Finally, we demonstrate how usage of this technique can support ac redundancy in a 2+0 PSU configuration when an ac feed fails, and the load exceeds the power rating of a single module. Read the article…

With smart ride-through, ac dropout
detection triggers a reduction in
the power supply load, which then
slows the discharge of the bulk
capacitor and increases the input
voltage to the dc-dc converter.

Additional reactive elements are
included in this more-complete
dynamic model of the PMS motor.

Motor Control For Designers (Part 7): Quasistatic And Dynamic PMS Motor Models

by Dennis Feucht, Innovatia Laboratories, Cayo, Belize

Step-motors are PMS motors with two phase-windings and many pole-pairs. The concepts presented in this part apply to PMS motors of any number of phase-windings by modifying the number of phase-windings, or “phases”. However, with just two phase windings, they provide a simple starting point for discussion of PMS motor models and a concrete illustration of their use. A review of the motor electromechanical model from part 4 and torque-speed graphs is followed by some aspects affecting motor-drive design: the voltage drive requirement V_g for full performance. The dynamic motor model presented in this part is a more-complete version of the model presented earlier, and allows us to observe the dynamics of the motor in the frequency domain. Meanwhile, the quasistatic model, is also useful, allowing us to determine the torque-speed characteristic of the motor. Read the article…

Redefining Q_SW To Obtain Accurate Switching Loss Estimates In RESURF-Based MOSFETs

by Orion Kress-Sanfilippo, iDEAL Semiconductor, Bethlehem, Penn.

As superjunction and other RESURF-based MOSFET architectures have become dominant in medium- and high-voltage converters, designers have increasingly observed a divergence between calculated and measured switching losses. In many cases, loss estimates derived from datasheet Q_SW exceed measured values by a significant margin, even when operating conditions are well controlled and measurement techniques are sound. This discrepancy reflects a fundamental mismatch between the traditional definition of Q_SW and the actual voltage and current waveforms observed in modern devices. This article reviews how assumptions about MOSFET switching behavior are used to calculate switching loss accurately in planar MOSFETs. It then explains why these assumptions are not valid in superjunction and other RESURF MOSFETs, leading to overestimations when the switching loss equation is applied. Read the article…

The period of voltage-current overlap
in RESURF devices differs from that of
planar transistors due to evolutions in
capacitance characteristics.

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

Inductor Analytical Model And Its Inductance Dependence On Current

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

Existing models of inductors are mainly intended for usage in simulation programs and do not have all of the inductor's parameters that have to be considered. This article offers an analytical expression for an inductor's inductance. The method described in this article and the supporting plots should significantly facilitate electronic designs incorporating inductors. The analysis is based on an analytical hysteresis loop equation, which may be familiar to the readers from my prior work. The goal of this publication is to obtain the dependence of the inductor's inductance on the current through the inductor. The resulting formula looks pretty bulky but it accurately reflects the inductance vs. current relationship, which will help designers select the appropriate inductors for their applications. Read the article…

INDUSTRY EVENT

Coiltech Is North America’s Coilwinding Hub

On June 10-12, 2026 members of the coilwinding industry will gather at Coiltech North America 2026 in Novi, Michigan. Participants will be engineering professionals and technical specialists who design, manufacture, and operate electrical machines—from raw materials to finished machines, and everything in between. This is a focused, specialized trade fair that wastes neither time nor attention, where materials, processes, and systems meet. The event will be held at the Vibe Credit Union Showplace. Read the full story…

POWER PRODUCTS

INDUSTRY EVENTS

OCP Canada Tech Day Aims To Accelerate Open Data Center Innovation

OCP Canada Tech Day, which will be held June 10-11, 2026 in Montreal, will bring together Canadian technical and business leadership, along with the OCP community, to discuss and share progress and ideas important to advancing AI data centers, hybrid classical and quantum data centers and extending AI from data center to the user. The event is intended to showcase the latest innovations and technical advancements from around the world. Read the full story…

With 300+ Exhibits, PCIM Asia Shenzhen Presents The Latest Power Electronics Products

PCIM Asia Shenzhen, which will be held August 26-28, 2026 at the Shenzhen World fairground, is an international exhibition and conference focusing on the power electronic device industry chain in Asia. It is a first choice platform for well-known domestic and foreign device manufacturers to release new products and the latest technologies. A number of enterprises in the field of electronic materials, inductive components and passive component products will debut for the first time. Read the full story…

OTHER TOP POWER NEWS

Registration for ECCE 2026 is now open for the upcoming conference in Vancouver, Canada.

Registration is now open for the IEEE Nuclear and Space Radiation Effects Conference (NSREC 2026), which will be held July 20 - 24, 2026 in San Juan, Puerto Rico.

3D-PEIM has added four two-hour tutorials to its program: “Advanced Packaging,” “Die-Attach by Metal Powder Sintering…,” “Digital Twin-Driven Reliability and Prognostics in Power Electronics Systems” and “Trends in Magnetic Material Properties to Meet the Challenges of Supporting High-Performance Computing”.