In this page, you will find many documents that I wrote recently or years ago. Some of them were the object of an article, some are exclusive to this site.

A PFC in borderline conduction mode with LTspice describes how to simulate a single-phase low-power PFC with an averaged model first and then with a cycle-by-cycle circuit to confirm stability is ok. The LTspice files are in the models page.

3-Phase PFC with dq0 control simulated with SIMetrix and LTspice. This document shows how I built a complete 3-phase PFC with averaged modeling for compensating the loops. The SIMetrix files are in my set of free templates while the LTspice files are in the models page. Small-signal model of the Weinberg converterdescribes how I derived the control-to-output transfer function of the Weinberg converter operated in voltage-mode control. The document shows how the PWM switch model excels in this analysis together with the FACTs. The final expression reveals the presence of a second zero whose position varies depending on the two transformers turns ratios.

A unified PWM switch model for CM and VM control with automatic transition between DCM and CCMis a paper published by Ulrich Burkhard who is with the Baden-Wuerttemberg Cooperative State University, Germany. The paper discusses how to combine auto-toggling models for VM and CM in a unified subcircuit, capable to operate in these two control schemes while still toggling between DCM and CCM. Simulations are done with LTspice. There is a YouTube video available here.

Ohmpilot ac-to-ac converter: I have recently installed a 3-kW solar generator in my garden and I wanted to store the surplus of energy elsewhere than in a battery. I have found the Ohmpilot from Fronius was a cool solution to implement. It basically adjusts the ac voltage applied to a boiler resistance from 0 to 230 V rms in relationship to the excess of energy. Unlike triac-based dimmers, the inverter implements an ac-to-ac buck converter that I simulate in the PPT. And it works well as the graphs in the end of the document show. The French version is here.

Loop compensation for the NCP1680: in this short document, I show how I did simulate the digital compensator found in the NCP1680 and NCP1681 totem-pole PFCs.

Compensating a buck converter with a type 3 OTA: I have often seen application notes in which an OTA was compensated like if it was an op-amp: stay away from this option and learn how to properly build a type 3 with an OTA provided you understand where the limit is.

Dc-shift compensation of a DAB converter: further to the seminar I proposed about the DAB converter, I realized that the insertion of a dc-block capacitor can be costly and impractical in many cases. Especially in bidrectional converters where two capacitors are needed. The method I have simulated is the analogue implementation of a digital approach described in this paper.

PCIM 2023 - I was presenting a poster on Thursday the 11th of May in Nuremberg and this is the presentation I built. It described the implementation of a 500-W LLC digitally controlled with an STM32G4. The loop combines a cheap analogue front-end integrator built around a TL431 and an optocoupler to which a pole-zero pair coded in C is added in the non-isolated side.

Type 3 compensator for the TL494: Some people still use the TL494 PWM controlller which is well suited for push-pull applications considering its two complementary outputs. Unfortunately, the two on-board op-amps are ORed in such a way that you need to wire them in a non-inverting configuration for regulation purposes. As I could not find design equations for a type 3 in this mode, I derived a transfer function and applied it to a buck converter.

Transfer Function of a CLLC Converter: This is a good example showing how the fast analytical circuits techniques or FACTs can help determine the transfer function of a 4th-order system painlessly without writing a single line of algebra.

Introduction to the DAB: This introductory seminar offers an overview of the dual-active bridge converter or DAB and explores the stress endured by the switches and the output capacitor.

Writing Guidelines: Proper writing is part of engineering excellence and there are rules you must obey when you work on presentation materials or write an article. This guide has been written by my late friend and former colleague Chuck Mullet. It will teach you how important it is to insert a space between the number and the unit (3 A, 2 kW and not 3A or 2kW) or write ac-dc or dc-dc converters (all lowercased, with a dash and not a slash). Something I also underlined in my document on presentation skills.

Introduction to Power Factor Correction: This short seminar gives an overview on power factor correction, where it comes from and what are the currently-available solutions. Many examples with simulation results are proposed in this document.

Control Methods of LLC Converters: This 90-mn seminar offers an introduction to LLC converters without entering into design details. Then the document reviews some modern control techniques like charge control or current-mode control.

Introduction to Switching Power Supplies: This is a new 90-mn seminar I recently built for new comers to the switching world. The document smoothly starts with linear regulators and then goes through the basic switching cells and their isolated derivatives.

Simulating with SIMPLIS: This seminar offers an introduction to the simulation of switching converters using SIMPLIS, a piece-wise linear simulation engine offering lightning-quick simulation time which can extract the small-signal ac response from any switching circuits. I used this program extensively in my last book on transfer functions. For those interested by the subject of simulation, this seminar from Chris Swartz from Vicor is well documented.

Starting with Elements: Elements is the free demonstration version from SIMPLIS and lets you simulate many circuits including isolated switching converters. You can also download the version including notes where you can read the comments going along with the slides. A good companion for my last book on transfer functions!

The TL431 in Switching Converters: I built this seminar for an Asian tour back in 2009 and it describes how to use a TL431 in the classical compensators types like 1, 2 and 3.

SPICE Predicts Differential Conducted EMI: I remember publishing this article in EDN, in 1997. I was describing how you could use a SPICE simulator to predict the conducted noise signature of your switching converter and see how the filter could be accordingly designed. The on-line version does not print pictures which is a problem. You can find the PDF version with pictures here.

Compensators in SIMPLIS: look at these types 1, 2 and 3 with automated compensation values around op-amps or a TL431 for the type 2 and an optocoupler. I have recently updated the examples with type 2 and 3 implemented in a digital way in SIMetrix or SIMPLIS. A digital PID is also there and all these compensators automatically compute the digital and analogue coefficients to meet the design criteria.

Measuring the loop gain from the output impedance: this is an attempt I've recently tried first by looking at the theory but, unfortunately, I did not find the time to pursue my experiments. These papers from Ridley and Gunma University can be consulted for more practical aspects. This method is not a substitute to regular stability measurements and can even lead to wrong results if probing is incorrectly done.

The impact of the current loop crossover on CM instability: read how the small phase margin in the inner current loop brings instability in a current-mode-controlled power supply. I have also detailed how the feedforward gains of Ridley's models were determined here. Also, if you want to run the simulations as described in the article, the ZIP contains the examples which run on the demo version Elements.

A small-signal model of the RPM buck: the constant-on-time (COT) converter keeps a constant on-time while the off-time is adjusted for regulation purposes. In current-mode control, the inductor valley current is set by the control voltage. A variant has been patented in 2009 which allows a dynamic adjustment of the on-time when a transient occurs. This is the ramp pulse modulation (RPM) concept and I have determined its transfer function in this PPT using the PWM switch model.

Importing SIMPLIS plots in Mathcad: this file teaches you how to import ac data obtained with SIMPLIS into a Mathcad file for response comparisons. The examples are here. Thank you to Simon Tian for showing this.

A multiplier with SIMPLIS: you cannot dynamically multiply variables in SIMPLIS without resorting to a log-based circuit. Nothing complicated once you have the subcircuit.

A 6th-order transfer function with FACTs: I show in this PPT how to derive the transfer function of a 6th-order Bessel filter made of cascaded cells. The Mathcad sheet is in the ZIP file.

A 5th-order transfer function with FACTs: I show in this PPT how to derive the transfer function of a 5th-order filter made of cascaded RC cells. The Mathcad sheet is in the ZIP file.

Over power Protection in the forward converter: this document details how a forward converter can possibly deliver more power at low line than in high-line conditions. The associated Mathcad 15 file is here.

Switching-Converter Dynamic Analysis with Fast Analytical Techniques: this document is a quick introduction to the fast analytical circuits techniques or FACTs and apply them to a DCM-operated SEPIC. It was published in the IEEE Power Electronics Magazine from September 2017.

The video of my tour in China, in 2018: it was a great experience, coached by the friends of 21DianYuan, I gave speeches in four big cities in China, starting with Beijing, Xi'an, Shanghai and Shenzhen across a 10-day tour. Very pleasant experience and many readers I was happy to chat with. I signed many copies of my books as the below pictures show. Patrick, my friend from Taiwan, was in Shanghai for translation assistance and we've had good time.

FACTs applied to a type-3 compensator: this document details how to derive the transfer function of the type 3 compensator when the open-loop gain AOL is involved. The Mathcad sheet is here.

Current mode simulations with VM-PWM switch: this document shows how you can re-use the original voltage-mode PWM switch model and by adding a simple resonating capacitor, turn it into a current-mode model able to predict sub-harmonic oscillations in CCM with dc and transient capabilities. It uses the models ported to LTSpice by Didier Balocco (see several lines below for download) and builds on experiments kindly done by Mark Dimattina. The LTspice files are here.

Op-amp interaction with Type 2: this Mathcad 15 file shows the impact of the op-amp open-loop gain and its two low- and high-frequency poles in a type 2 compensator. It is usually not a problem for low crossover frequencies but as soon as you need gain and phase boost at values at or beyond 10 kHz, the GBW product matters. The PDF is here.

Leakage inductance effects in the flyback converter: this 3-part article originally published in How2Power.com describes how the leakage inductance affects the conversion ratio of a flyback converter by truncating the duty ratio. Power dissipation via the clamping network also damps the control-to-output response as modeled through a new average circuit.

Zeta converter with the PWM switch: this short PPT shows how you can wire the PWM switch model to simulate the control-to-output response of a Zeta converter.

Active Clamp Forward in Current Mode: this short PPT shows the ac simulation results I was able to obtain with my voltage-mode model to which a duty ratio factory was added. Results are not far from what Simplis predicts.

Duty Ratio Factory Modeling in a CCM CM Buck Converter: this presentation shows how to independently model the control voltage Vc to duty ratio D block in a current mode converter. The presentation explains that by using a voltage mode stage to which a separately-modeled Vc-to-D is added, you obtain the complete control-to-output transfer function of the CCM CM buck converter.

Presentation skills: I have been teaching and speaking in front of an audience for a while now. My first speech, which goes back 20 years, was a complete disaster: trembling voice, shaky legs and so on. I made the obvious mistakes untrained people do and with time, I started to improve by learning from professionals. I also took several presentation skills classes and I improved over years. At least I hope I did : ) For those who need to present, I compiled most of the mistakes you must avoid to make your speech efficient and credible. I have one in French as well.

Small-signal analysis of the fixed current mode variable frequency flyback converter: this presentation teaches you how to derive the transfer function of a flyback converter operated in constant peak current while switching frequency is controlled. This technique is now widely used in converters implementing frequency foldback in light-load conditions.

Genuine type 2 compensator with the TL431: this short document shows you that a real type 2 built with a TL431 and involving two lanes is not wired as a type 2 with an op amp: a single capacitor is enough across the TL431. Adding an extra RC is useless.

Calculating the bulk capacitor parameters in an offline converter: this paper updates the current book content by improving the formulas used to derive the bulk capacitor value in a front-end rectifying section. Nothing spectacular here but I realized that these results could help the design community to calculate the right value.

An average model for the phase shifted converter: this document shows how I built an auto-toggling average model for the phase shifted converter. The model exists in IsSpice but also in PSpice. Both average and generic cycle-by-cycle models are available in ready-to-use templates describing a 12-V/25-A power converter. They are part of the distributed library files.

The TL431 in loop control: the TL431 is never studied as a part of the compensator in control theory books. However, this is a market reality, op amps are rarely used! Go through this new series of articles and learn how the TL431 works and how you can use it in a variety of configurations.

The RHPZ, a two-way control path: the Right-Half-Plane-Zero plagues the flyback or the boost converters operated in CCM. This paper explores the origins of the RHPZ.

Stability Analysis in multiple loop systems, S. Conseil, N. Cyr, C. Basso: a TL431 combines a fast and a slow lane. How to measure the total loop gain combining both lanes is the object of this paper.