ISSUE: February 2017


To ensure receipt of future issues, please add to your address book. Visit



» Understanding Op Amp Dynamic Response In A Type-2 Compensator (Part 2): The Two Poles

» Fast, Simple Solenoid Driver Saves Power In Industrial Applications

» A Practical Primer On Motor Drives (Part 13): Motor Drive Control Architectures And Algorithms

» Phase Angle Regulation Versus Impedance Control: Which Offers Greater Control Of Power Flow On the Grid?

» Focus On Magnetics:
Eddy-Current Effects In Magnetic Design (Part 5): Winding Design Optimization

» Book Review:
Enduring Text Offers Complete Compendium Of Motor And Drive Concepts

» New Power Products

» What's New at

» Other Top Power News

From the Editor's Desk

David G. Morrison
Editor, HOW2POWER TODAY       

Industrial applications present countless and diverse opportunities for power electronics solutions that save energy or improve other aspects of system performance. Several articles in this issue offer information that may help engineers address some of these application needs. First, we have a continuation of Ken Johnson’s primer series on motor drives. His latest installment explains the fundamentals of motor drive control architectures and algorithms. Those interested in motor drives will also want to read Dennis Feucht’s review of the recently published text “Electric Drives” by Boldea and Nasar. Anyone curious about solenoid driver circuits may appreciate Gregory Mirsky’s short article, which provides a simple yet energy efficient approach to driving solenoids at high repetition rates. And finally, we have a feature by Kalyan K. Sen and Mey Ling Sen comparing phase angle regulators with an impedance control technology for power flow control on the grid. Although this article does not focus on a power electronics-based form of control, it may offer valuable insights to those looking to develop such controllers. Back in the world of switched mode power supply design, this issue presents the conclusion of Christophe Basso’s two-part series on modeling the effects of real op amp characteristics on type-2 compensators. This issue also brings readers another part in Dennis Feucht’s series on eddy current effects in magnetics design, plus power component news and more.


Understanding Op Amp Dynamic Response In A Type-2 Compensator (Part 2): The Two Poles

by Christophe Basso, ON Semiconductor, Toulouse, France

In part 1 of this article, we have shown the impact of the operational amplifier open-loop gain AOL on the response of a type-2 compensator. Pushing the analysis further, a closer look at the magnitude and phase response of an op amp reveals the presence of two poles—one low frequency and one high frequency. While these poles can be neglected in low-bandwidth compensator designs, you must account for the distortion they produce when you need gain and phase boost in high-bandwidth systems. In this second part, we will see how to determine the transfer function of the type-2 compensator accounting for these poles and how they distort the response of the filter. As we will see, the op amp’s poles and finite gain produce distortions in the gain and especially the phase characteristics of the compensator. Fortunately, these distortions can be minimized by appropriate selection of the op amp and we’ll present a method for doing so.. Read the full story…

The open-loop dynamic response of an op amp reveals the presence of two poles (fp1 and fp2).

Energy stored in the solenoid inductor must be
dissipated quickly to allow a fast repetition rate.
This requires inductor current decay time
to be shortened through use of higher
voltage or driver circuit modifications.

Fast, Simple Solenoid Driver Saves Power In Industrial Applications

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

Conventional solenoid drivers have uncontrollable current decay arrangements. If a fast current decay is required, a higher supply voltage is used, which results in high power dissipation. Alternatively, an extra Zener diode may be connected in series with the solenoid recuperating diode. In that case a special external signal clamps the Zener diode during the driver active mode and releases it when its operation is necessary. Typically, a microcontroller is needed to control the Zener, which adds complexity. Or, if the Zener diode is connected on a permanent basis, the solenoid operates in a discontinuous conduction mode—this approach also dissipates a lot of power, creating heat and substantial EMI. To overcome these limitations, a new solenoid driver arrangement is proposed. Read the full story…

A Practical Primer On Motor Drives (Part 13): Motor Drive Control Architectures And Algorithms

by Ken Johnson, Teledyne LeCroy, Chestnut Ridge, N.Y.

Part 12 began the explanation of how VFDs operate by describing their overall operation and architecture, dc bus link topologies, and pulse-width modulation techniques. In this part, the discussion continues with an introduction to the popular VFD control architectures and algorithms. There are three primary methods for achieving variable-frequency motor control: scalar V/Hz, six-step commutation (also known as trapezoidal control), and vector control. One may implement all of these methods in an open loop (few or no sensor feedback signals from the motor) or closed loop (significant sensor feedback required from the motor) with various algorithms. Each of these control methods will be explored here. Read the article…

In six-step commutation control, the back-EMF influence
from a nearby (energized) phase on the adjacent
(non-energized) phase results in the “ramp up” or “ramp
down” of the peak voltage, and thus the trapezoidal shape.

The goal of power flow control is to
optimize the power transmission line to
achieve the highest amount of active power
flow that generates the most revenue at
the lowest amount of reactive power flow.

Phase Angle Regulation Versus Impedance Control: Which Offers Greater Control Of Power Flow On the Grid?

by Kalyan K. Sen and Mey Ling Sen, Sen Engineering Solutions, Pittsburgh, Penn.

Power flow control in electric transmission lines has long been attempted with the use of a phase angle regulator (PAR). But PARs have performance limitations. Two decades ago, a new impedance regulation method was attempted using a mostly power electronics-based controller called a UPFC. Although the UPFC was not commercially successful due to high cost and component obsolescence issues, experience with this technology led to the development of the Sen Transformer (ST). This article presents a comprehensive comparison of PARs and the ST, which will help utilities to make informed decisions when choosing power flow control solutions and may inspire power electronics engineers to develop more practical UPFCs. Read the full story…

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

Eddy-Current Effects In Magnetic Design (Part 5): Winding Design Optimization

by Dennis Feucht, Innovatia Laboratories, Cayo, Belize

In Part 4, Dowell’s equation was presented. It provides a graphic way of determining winding loss for a given wire size and number of layers. Having that capability, we now progress to the problem of how to optimize wire size for minimum winding resistance. Given the two winding design parameters, ξ and M (with frequency, f given), the winding design goal is not to minimize FR in itself but to minimize winding loss, . To achieve this goal, we will transition from FR to Fr , which is proportional to . Whereas FR is the resistance ratio with constant wire size and varying frequency, Fr instead has constant frequency with varying wire size. We can thereby find the optimal wire size using Fr. Ultimately, we will find there are two possible solutions for minimizing eddy-current effects—a low-ξ solution involving a smaller wire size and a high-ξ solution involving a larger wire size. Read the full story…


Enduring Text Offers Complete Compendium Of Motor And Drive Concepts

Electric Drives: Third Edition, Ion Boldea, S. A. Nasar, CRC Press, ISBN-13: 978-1-4987-9, glossy hardback, 650 pages, 2016.

Reviewed by Dennis Feucht, Innovatia Laboratories, Cayo, Belize

The leading author of this book, Ion Boldea, is an engineer at the University Politechnica and Romanian Academy in Timisoara, Romania, and an IEEE Life Fellow. The book is in its third edition, ten years after the second, and includes some new material, notably “sensorless” control. The subject of the book is motor drives, which is mainly about electronic power circuits and control theory as applied to electric machines including various mechanical loads. Naturally, as most authors on the subject have discovered, some theoretical background on electric machines is unavoidable. This book is no exception. Read the full story…

Vicor Logo


How the Power Component Design Methodology Delivers Optimized LED Power Systems

Although LEDs are an efficient, systems have an increasing need for power, driven by the use of brighter LEDs, more LEDs in panels and more panels within the system. There is also a need to reduce size and weight to accommodate compact form-factors and make mounting the panels easier. Read this blog post to learn how the power component design methodology helps power designers achieve these challenging goals.

Read this article

More from Vicor:

On-Demand Webinar Makes Worrying About EMI a Thing of the Past

Analyzing Bi-Directional Power Components Using the Vicor Whiteboard

Scalable, Low Weight DC-DC Solution with High Capacitive Loads



Navitas Semiconductor’s
iDrive Gallium Nitride power ICs.

GaN Power ICs Enter The Market

 Diagram: The most integrated of the new GaN power ICs, the NV61159 combines a 650-FET with driver and logic circuitry and a voltage regulator.

 Waveforms: Monolithic integration of gate driver and FET enables short propagation delays and fast and clean rise and fall times on the switch-node waveforms.

 Graph: Having the driver and FET on the same chip eliminates the need for a gate resistor to suppress voltage spikes during switching. Eliminating the gate resistor, in turn, dramatically reduces turn-off losses.

More details…

Powerbox’s GB350
buck-converter module.

Coreless Buck Converter Provides Efficient Point-Of-Load Power In MRIs And Particle Accelerators

 Photo: The GB350 buck-converter module delivers an output power of 350 W while operating in the presence of high radiation magnetic fields of 2 to 4 Tesla. Target applications include MRI scanners and particle accelerators.

More details…

ISL78693 3.6-V
battery charger IC.

Battery Charger Extends Backup Battery Life In Automotive eCall Systems

 Photo: With its very low 3-µA leakage current, the ISL78693 single-cell battery charger IC extends the runtime of lithium iron phosphate backup batteries used in automotive emergency call (eCall) systems.

 Diagram: The chip offers simplicity and ease of use, requiring only five external passive components to program the full charging platform.

 Diagram: In addition to other capabilities, it features a unique charge-current thermal foldback that prevents overheating by automatically reducing the battery charging current.

More details…

Allegro MicroSystems
Europe’s A3916
motor driver IC.

Motor Driver IC Requires Only Four External Components

 Diagram: Requiring just four external components, the A3916 dual DMOS full-bridge motor driver IC is designed for PWM control of low-voltage stepper motors or dual dc motors, delivering up to 1 A per channel. The chip operates from a 2.7-V to 15-V supply.

 Diagram: The chip features integrated PWM current control, two DMOS full bridges with low on-resistance outputs, synchronous rectification for reduced power dissipation, an integrated charge pump and fault protection including overcurrent protection, undervoltage lockout and thermal shutdown.

More details…


• Industrial Sinewave Inverters Deliver 400-VA From 600-Vdc Input    More details…

• Intelligent Power Modules Offer More Packages, More Features For Appliancess    More details…


DC-DC Converters For Space

This section presents information to help designers find rad hard dc-dc converters and voltage regulators for space applications such as satellites and spacecraft. This section covers both fully functional dc-dc converter modules as well as power ICs. It also links to related design articles and space-focused conferences. View this section…



On Monday morning, March 27, 2017 at APEC 2017 in Tampa, Christophe Basso will teach a professional education seminar on “Input Filter Interactions with Switching Regulators.” An abstract for this seminar is available here.

On February 22, 2017 at the Teledyne LeCroy Automotive Technology Center in Farmington Hills, MI, Ray Ridley will present two lectures—one on “Modern Topologies” and one on “Modern Magnetics Design.” Click here for more on this lecture series.

Efficient Power Conversion (EPC) has opened an Applications Center in Blacksburg, Virginia.  This center will increase the reach of EPC to support research and development for the applications of enhancement-mode GaN transistors and ICs.

The preliminary agenda for the 2017 Annual CPES Conference is now available!