Marc Cousineau

Multiphase coupled converter models dedicated to transient response and output voltage regulation studies

In order to study transient response and output voltage regulation in multiphase coupled buck converter, it is proposed two models of interleaved coupled buck converter. These two models provide accurate current and voltage waveforms for any value of duty cycle. In the first part, the two proposed models are described in details. In the second part, it is shown the interest of this approach to study dynamic behaviour and determine compensation filters for voltage regulation in a multiphase coupled buck converter.

Fully masterless control of parallel converter

In this article a fully decentralized modular approach (real masterless) for parallel converter control is presented. A control circuit assigned to each switching cell, communicating with its neighboring circuits, is presented in detail. It is able to provide the computation of the common mode duty cycle, the balancing of the leg currents and the proper phase shift for the interleaved carriers of the converter in a decentralized manner. The identical control circuits are connected together in a daisy-chain configuration. Then, the implementation of a converter using a large number of parallel legs (ten to hundred) becomes easy. It works regardless of the number of legs and provides the ability to add or remove dynamically a leg easily. In order to help the designer, a stability study for the current sharing loop is provided. A test board demonstrates the validity of the solution. Moreover it shows that, using this modular control approach, a leg of the converter can be added or removed dynamically without any additional control consideration.

Modular control of parallel isolated micro-converters dedicated to conversion network

In this paper, an original control method used to regulate a micro-converter is presented. A network of micro-converters is dedicated to photovoltaic or bio-battery power conversion applications. This network combines several micro-converters in parallel to provide a high output current. Each micro-converter (5V, 2A) use a multi-leg transformer with several coupled inductors. A modular approach for the control of each internal switching cell is chosen. It consists in an original masterless control method used to generate a perfect shift of the interleaved carrier phases using a self-alignment process, and to provide the balancing of the internal inductor currents. At last, the control of a micro-converter is implemented in an integrated circuit with a targeted 1MHz switching frequency.

High frequency EMC impact of switching to improve DC-DC converter performances

This paper presents an analysis of the high frequency disturbances from switching operation in a SoC (System on Chip) Buck converter for EMC (Electromagnetic Compatibility) performance improvement. The impact of key design parameters is handled with an analytic approach, allowing Conducted Emission (CE) spectrum prediction.

Concept and design of hybrid interleaved and isolated micro-converter for low power applications

In this paper, a hybrid interleaved and isolated micro-converter (5V/2A/1MHz) dedicated to low power conversion is presented. In order to be able to address a lot of different applications, its structure is isolated (implementation of a planar coupler) and uses interleaved parallel legs with coupled inductors (lowering internal losses). For very high integration purpose, two chips have been done: one dedicated to the control of the switching-cells and the other implementing the drivers and the power switches. The control part implements an original modular approach dedicated to provide the interleaved carriers and to guaranty the current balancing. The power part discusses the layout constraints to optimize the power density.

Benefits of multiphase Buck converters in reducing EME (Electromagnetic Emissions) Analysis and application to on-chip converters for automotive applications

Inside the car, all integrated circuits “IC” have to be optimized to survive against severe external aggressions. The noise generated by each activity inside each IC must be low enough, to not disturb the environment. As known nowadays, DC-DC converters can significantly impact the Electromagnetic Compatibility “EMC” performances, and mainly the emission ones. Unfortunately, simulation with linear models like ICEM or IBIS models [1, 2] remains very challenging for integrated analogue products due to the high number of parameters, plenty of possible applications and the extent of the frequency domain where the integrated circuit must be compliant. A paper describes an analytical approach to highlight the main contributors to the high frequency noise generated by switching activity in Buck converters [3]. This approach is here employed to evaluate Conducted Emission “CE” performance of multiphase interleaved Buck converters and to highlight benefits of increasing the number of phases in improving the emission profile.

Interleaved converter with massive parallelization of high frequency GaN switching-cells using decentralized modular analog controller

Interleaving switching-cells is an appropriate approach to increase current capability of power converters and, at the same time, to increase the converter efficiency. Improvement in the power density of these converters can be achieved by the use of high-performance switches, such as wide bandgap semiconductors, with the consequent increase in the switching frequency. We develop here a fully decentralized analog controller which automatically generates “very” high frequency interleaved carriers for a buck converter with high number of switching-cells. Also, this controller regulates the output voltage (voltage regulation loop) and compensates current unbalance between the switching-cells (current sharing loop) using an innovative control technique. Furthermore, since the controller has a modular structure in a Daisy chain configuration, the number of switching-cells in operation can be automatically selected in order to maximize the converter efficiency for different output power. Besides that, Adaptive Voltage Positioning (AVP) technique is used in the controller in order to limit under and over voltage for different load variations and, at the same time, to increase the system dynamics. The controller operation is verified in a 12/5V buck converter having up to 25 interleaved switching-cells composed of Gallium Nitride transistors switching at 500kHz.