Power Converter Topologies for a High Performance Transformer Rectifier Unit in Aircraft Applications

This paper presents some power converter architectures and circuit topologies, which can be used to achieve the requirements of the high performance transformer rectifier unit in aircraft applications, mainly as: high power factor with low THD, high efficiency and high power density. The voltage and the power levels demanded for this application are: three-phase line-to-neutral input voltage of 115 or 230V AC rms (360 – 800Hz), output voltage of 28V DC or 270V DC(new grid value) and the output power up to tens of kilowatts

Overview, equivalences and design guidelines of v1 concept: A voltage mode control that behaves as a current-mode with near time-optimal response

This paper summarizes the proposed v1 concept, that explains how by only measuring the output voltage, designers have information about almost every signal of the power stage. Following the v1 concept, the implementation of some ripple-based controls as a conventional voltage mode control or current mode control is studied. Based on these, it is explained how to design a traditional type-III voltage mode control to behave like a current mode control with near time-optimal response under load transients. The work is validated in simulations and experimentally on a 300kHz Buck converter

An optimization algorithm to design fast and robust analog controls for Buck converters

Ripple-based controls are popular to achieve a fast dynamic response, but the design of these controls assuring robustness is not easy due to its intrinsic nonlinear nature. These techniques often rely on sensing networks heavily dependent on parasitic elements to estimate the inductor current or the capacitor current. Consequently, a modeling technique that takes into account these sensors and parasitic elements is needed. This paper proposes an optimization algorithm to design a wide variety of controls that can take into account the parasitic elements and tolerances of the converter. The proposed algorithm can be used to design very fast controls that are also robust in a real-world implementation. This algorithm is verified on a 300kHz Buck converter with Voltage mode and a 1.3MHz Buck converter with V2Ic control

v1 concept: designing a voltage mode control as current mode with near time-optimal response for Buck-type converters

This article introduces the v1 concept, that explains how by only measuring the output voltage, designers have information about almost every signal of the power stage. Following the v1 concept, it is explained how to design a traditional type-III voltage mode control to behave like a current mode control with near time-optimal response under load transients. The work is validated in simulations and experimentally on a 300kHz Buck converter

A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize Efficiency and Extractable Power

Wireless power transfer (WPT) is an emerging technology with an increasing number of potential applications to transfer power from a transmitter to a mobile receiver over a relatively large air gap. However, its widespread application is hampered due to the relatively low efficiency of current Wireless power transfer (WPT) systems. This study presents a concept to maximize the efficiency as well as to increase the amount of extractable power of a WPT system operating in nonresonant operation. The proposed method is based on actively modifying the equivalent secondary-side load impedance by controlling the phase-shift of the active rectifier and its output voltage level. The presented hardware prototype represents a complete wireless charging system, including a dc-dc converter which is used to charge a battery at the output of the system. Experimental results are shown for the proposed concept in comparison to a conventional synchronous rectification approach. The presented optimization method clearly outperforms state-of-the-art solutions in terms of efficiency and extractable power

Impact of the control on the size of the output capacitor in the integration of Buck converters

One of the main challenges in PowerSoC converters is the integration of the output capacitor. In some applications, the minimum value of the capacitance is constrained not by the maximum allowed voltage ripple but by dynamic requirements. This paper investigates for a 10 MHz Buck converter if the design of very fast controls can reduce the required output capacitor and which controls are more suitable. It is also analyzed the effect that the moment in which the load transient can occur has on the reduction of the size of the output capacitor

Analysis of the effect of modulation delays on the size of the output capacitor

Constant frequency (PWM), constant on-time (COT) and constant off-time modulations exhibit inherent delays where the controller is unable to respond instantaneously. These delays can increase the required size of the output capacitor to meet dynamic requirements in applications with high demanding load such as the supply of microprocessors. This paper analyzes the minimum required output filter (output inductor and output capacitor) to meet a given specification and quantifies the effect that different modulations have in the minimum size of the output capacitor. The paper also shows a novel technique to mitigate the delays of the modulations by means of synchronizing the load step with the clock of the modulation. This technique is applicable to most of controllers as it only acts on the modulator

Improved transient response of controllers by synchronizing the modulator with the load step: application to v2ic

V2Ic is a ripple-based control with an excellent performance for load transients and reference voltage tracking because it exhibits a feedforward of the load current and the error of the output voltage. However, if V2Ic is modulated with constant frequency, constant on-time or constant off-time, its dynamic response is hindered by delays in the response. This paper proposes a technique that synchronizes the clock of the converter to initialize the duty cycle when a worst-case load transient occurs using the current through the output capacitor to detect load transients. It is exemplified on a V2Ic control but it is applicable to most of controllers as it only acts on the modulator

Optimization and analysis of PwrSoC Buck converter with integrated passives for automotive application

Current trends in automotive industry impose as main drivers the improvement of the efficiency and the miniaturization of the electronic systems. New technologies for passives enable the integration of inductor based power converter together with the load in a single chip. Due to the complexity of the system and various constraints, multi-variable optimization needs to be employed. This study presents an energy-based piece-wise linear model for switches losses estimation for 40 nm automotive approved semiconductor technology used for implementation of PwrSoC buck converter system. The model, based on discrete number of calculations performed with Spice simulations, is presented in detail in this study and it is validated experimentally

45kW Full Bridge Converter with Discontinuous Primary Current for High Efficiency Airborne Application

This paper presents and describes the design and optimization process of a high power density 45kW DC/DC converter for aircraft application. This onverter is a part of an isolated rectifier for a military aircraft pulsating load. It has to provide galvanic isolation and good stability when the load steps as high as 40 kW are applied. In order to obtain high efficiency, on the primary side of the converter a discontinuous triangular current modulation is implemented. High power density is obtained by relatively high switching frequency of 10 kHz and by implementation of the transformer using a nanocrystalline material that enables high magnetic flux density (up to 1T) and copper foils for conductors. The expected efficiency of the converter is 97.6% and the total weight of the system is 7.6 kg