Martin Ordonez

University of British Columbia - Vancouver | UBC · Department of Electrical and Computer Engineering

CLLC resonant converters are an attractive option for battery charging applications due to their bidirectional power flow and high efficiency. Pulse frequency modulation (PFM) is the simple method to drive CLLC converters. However, PFM cannot regulate the output voltage under the light-load condition properly, which leads to high switching and core...

Modern architectures of transformerless, three-phase-grid-connected photovoltaic (PV) inverter for 1000- and 1500-V commercial/residential applications are analyzed and compared from the point of view of the energy harvested during one year period, system efficiency, and power density. Scenarios for different ac grid voltage levels and inverters to...

Synchronous rectification (SR) technologies for $LLC$ resonant converters are essential to high-power, low-voltage battery chargers considering the excessive current stress on the rectifiers. Mainstream SR controllers employ an adaptive approach that measures the drain–source voltage during the SR turn-on phase ( $v_{\text {ds.on}}$ ). However,...

Integrating Distributed Generators (DGs) in DC microgrids require islanding detection in all converters. Impedance-based islanding detection methods can be beneficial in single-converter scenarios. However, their implementation in multi-converter systems is challenging due to interference among DGs. This paper proposes a Leader/Follower strategy fo...

Since microgrids with renewable generation and energy storage can achieve high reliability, they present an attractive solution for powering critical loads. Microgrids should be carefully planned and optimized to meet the power requirements of critical loads and justify their economic viability. Conventional microgrid design approaches consider a f...

Three-Phase converters are controlled to achieve sinusoidal currents in the grid side and tight voltage regulation in the DC-link. Linear controllers based on small-signal models is a well-established solution for these converters. However, the dynamic performance can be improved only to a limited extent and it deteriorates under different operatin...

Three-phase CLLC resonant converters provide higher power conversion capability as compared to half-bridge and full-bridge structures. In addition to the unique features of CLLC converters for bidirectional applications, the three-phase structure provides significantly reduced output current ripple (smaller output capacitor), parallel power pro...

Three-phase Pulse-Width-Modulated (PWM) converters require of closed-loop controllers to meet the performance requirements and to achieve reliable responses over the entire operating range. Conventionally, by using the synchronous reference frame (SRF) representation, different linear and nonlinear control strategies have been proposed to improve t...

Charge control for resonant converters introduces an inner feedback loop that improves the system dynamic characteristics. However, small-signal modeling is not as straightforward with charge-controlled resonant converters as it is with current mode hard-switching topologies, due to the nature of resonant behavior. Conventional small-signal models...

High performance operation of inductive wireless power transfer (WPT) systems requires judicious tuning of the inverter connected to the transmission hardware to ensure high efficiency and power transfer. In many applications, disturbances to both the coupling condition and secondary side load reshape the system dynamics, motivating the design of c...

Wide-bandgap and silicon power semiconductor devices require advanced pulse-width gate-driver capability to successfully convert power for high performance operation. In this paper, a simplified forward isolated resonant converter structure with an integrated planar transformer is proposed, a cost-effective solution which eliminates the need of an...

Experiments based comparative analysis of digital PID (Proportional, Integrative, and Derivarive), LQR (Linear Quadratic Regulator), LQR with observer and integral action, and fuzzy logic controller is presented in this work. Well-known speed control of a DC servomotor was the application chosen to implement each controller due to its simplicity an...

The design of power electronics converters for fuel cell systems requires a comprehensive understanding of the Fuel Cell (FC) dynamics and steady state behavior. In this paper the dynamic behavior of a Direct Methanol Fuel Cell (DMFC) is investigated. The experimental results obtained from a flexible FC test bench are discussed and used to examine...

This paper describes the development of a Fuel Cell (FC) system model, which incorporates an optimization approach based on statistical Design of Experiment (DoE) methodology. DoE provides a very efficient method to obtain a model for the studied multivariable FC system. The optimization process, as well as an empirical parametric model, is present...

Wide-bandgap and silicon power semiconductor devices require advanced pulse-width gate-driver capability to successfully convert power for high performance operation. In this paper, a simplified forward isolated converter topology with integrated planar transformer is proposed which eliminates the need of output filter inductor while rearranging th...

Three-phase LLC resonant converters can handle much higher power compared to half-bridge and full-bridge LLC converters, which makes them suitable for level 2 and level 3 battery charger applications. In addition to the unique features of LLC resonant converters, the three-phase structure provides higher power capacity and higher power density at h...

Compensation capacitors are important components of any resonant wireless power transfer (RWPT) systems and significantly affect the output power, operating frequency, and efficiency. Depending on the compensation network, these capacitors can be placed in series or parallel with the coils. The physical capacitor reduces reliability and increases t...

Utility power lines voltage levels vary in different geographical locations, ranging from 208VRMS to 480VRMS. Power factor correction (PFC) converters are typically designed for a particular input voltage and do not accept a wide range of line voltages. This results in multiple product designs and revisions and increased production costs to accommo...

Traditional voltage mode and dual-loop current mode linear schemes are widely used for controlling the fundamental DC-DC converters due to their simple implementation and fixed-frequency PWM operation. While the dynamic response can be improved by pushing the control bandwidth, lower stability margins may lead to unexpected peak deviations in the i...

The rapid expansion of distributed energy resources has led to increasingly complex systems with numerous power converters. Accurate converter loss prediction in large grids and microgrids is essential for financial and reliability evaluation. Existing system-level analysis focuses on distribution losses and oversimplifies converter losses by assum...

Fringing losses play a detrimental role in high-frequency transformers. The tendency toward higher power density and miniaturization of power converters leads to higher switching frequency and enforces the use of low-profile components such as gapped planar transformers. Due to the air gap, lower magnetizing inductance and better regulation of LLC...

In the past ten years, LLC resonant converters have become a mainstream topology for dc/dc power conversion, and multiple design tools have been developed for this topology, including controllers, regulators, soft-switching techniques, etc. While many tools are available for designing this converter, techniques for accurately determining power lo...

The widespread use of the LLC converter in DC/DC applications has increased the importance of small-signal modeling to control the converter below to above resonant frequency. The analysis of the LLC converter is complicated, and therefore, its small-signal modeling is traditionally performed using empirical methods, iterative simulation approaches...

In the past years, LLC resonant converters have become a mainstream topology for DC/DC power conversion due to their advantages, such as the superior efficiency obtained with the soft switching of MOSFETs. In order to further improve the efficiency of the converter, synchronous rectification can be implemented as an alternative for diode rectificat...

Boost-based converters are used in a variety of non-isolated step-up applications, such as Power Factor Correctors (PFC), because of their simplicity. The power density of these converters can be increased in higher switching frequencies, which reduces the size of the magnetic elements. This increases the switching losses, but that can be solved by...

With the increasing demand for flat displays, slim telecom/IT power supplies, and portable devices, the use of Planar Transformers (PTs) is becoming mandatory to achieve slim, compact converter designs. In particular, PTs present a significant opportunity to replace tall and bulky wire-wound transformers in industry standard LLC converters. However...

Utility power lines have different voltage levels in different geographical locations, ranging from 208V RMS up to 480V RMS. Most of the current universal input voltage PFCs accept up to 270V RMS in the input, which restricts their applications. In this paper, a wide-input voltage universal PFC converter with high efficiency is introduced. The prop...

Rectification (SR) for LLC resonant converters has been developed to enhance the power conversion efficiency. Conventional SR driving strategies can be categorized as current-driven methods, vDS_ON sensing methods, and alternative approaches. The current-driven methods widely adopt current transformers (CTs) to sense the rectifier current and gener...

Due to its simplicity, the hard-switching Boost converter is widely used in many applications, such as renewable energy and power factor correction. The power density of the converter can be increased with smaller magnetics; however, this requires an increase in the switching frequency. Therefore, it is necessary to provide soft-switching condition...

The interest in distributed generators (DGs), especially those associated with renewable energies, has increased in recent years. The number of functionalities that their associated Voltage Source Inverters (VSIs) can deal with is rising, harmonic currents compensation being one of them. VSI control is in charge of accomplishing the different capab...

Three phase solar inverters can be operated with different modulation strategies such as sinusoidal pulse-width modulation (SPWM), space vector modulation (SVM), third-harmonic injection PWM (THIPWM). The selection of the modulation strategy can significantly affect PV leakage currents and power losses and compromise the inverter performance. This...

Dc microgrids interconnect load-end converters and distributed renewable energy sources within efficient and reliable networks that can operate independently from the main grid. When load-side converters tightly regulate their output voltages, they behave as constant power loads (CPLs), which can cause instability within the network. Traditionally,...

Thermal analysis is an essential design step of high performance power electronics transformers, enabling the designer to estimate temperature behavior of the components and provide a proper cooling system. In this paper, a thorough thermal analysis is carried out for two different types of transformers used in high frequency LLC resonant converter...

In this paper, a thorough thermal analysis is carried out in order to find an analytical 3D-frequency thermal model of planar transformers used in high frequency power converters. Because of the tendency of having miniaturization of power converters, the components have to work near their thermal limit margins. This issue is more critical for plana...

Three-phase LLC resonant converters can handle very high power levels beyond the capabilities of half-bridge and full-bridge LLC topologies. Among other characteristics, three-phase LLC structures reduce output current ripple (small output filter), enable parallel power processing (low peak current), and provide good thermal distribution. However,...

To further reduce losses in LLC resonant converters, the use of synchronous rectifiers (SRs) in the rectifier is inevitable. Analysis and detection of the conduction angles of SRs used in an LLC converter are the main challenges in synchronous rectification. This paper develops a new time domain theoretical analysis, called homopolarity cycle, enab...

Photovoltaic cells require of Maximum Power Point Tracking (MPPT) algorithms to ensure the amount of power extracted is maximized. True seeking, direct duty cycle control MPPT algorithms are a simple and straightforward solution that can provide high tracking efficiency. In these algorithms the duty cycle is traditionally modified to reach a new st...

In Electric Vehicles with rooftop PV panels, the solar irradiance and surface temperature can affect their performance and output voltages (e.g., Vpv = 24-45V DC). In these systems, the maximum energy must be extracted from the variable input voltage (PV panel), boosted by different gains, and stored in high voltage battery packs. Furthermore, depe...

LLC resonant converters have gained popularity in a wide number of industrial applications due to their high efficiency and power density. Common applications of this converter are battery chargers, electric vehicles and high efficiency power supplies which require tight output voltage regulations. However, traditional averaging techniques employed...

In order to support different types of rechargeable batteries (e.g. Li-Ion, Lead-Acid, NiMh), the design of universal battery chargers must focus on wide output voltage regulation, rather than on constant voltage regulation. The universal battery charger is expected to provide a demanding output voltage range between nominal and 1.5 times nominal,...

In order to enhance the efficiency of LLC resonant converters, a new synchronous rectification modulation technique, called homopolarity cycle modulation, is proposed. The proposed modulation technique answers the main challenge in synchronizing the LLC converter's rectifier, which is detecting the conduction angle. By observing the polarities of t...

Traditionally, single-input-multi-output power converters are used to power different parts of a system assembled on a printed circuit board (PCB). The imperfections of this strategy are well-known and include complicated PCB design and thermal management, poor load side voltage regulation, and reduced power density and efficiency. A DC distributed...

One main advantage of three-phase LLC converters for high power applications is their full-load efficiency. However, issues with light load operation (i.e. low efficiency) requires investigation. In this paper, a new modulation strategy is proposed to improve the light load efficiency of three-phase LLC converters to achieve a better efficiency cur...

Presents information on various PES Society chapters.

This paper presents a new approach for quasi real-time and adaptive energy management for islanded AC/DC microgrids using Advanced Metering Infrastructure (AMI) data. The paper presents a sophisticated multi-objective algorithm by employing AMI-based energy conservation and optimization techniques, tailored for different operational scenarios. The...

The addition of a more distributed generation in the electrical grid is poised to rapidly improve the sustainability of electric power generation and energy security, while reducing cost. The electrical grid is an aging century-old large infrastructure mainly based on large (GW) electrical central power stations that have slow dynamics. Grid integr...

Flyback and Forward converters are two commonly used topologies for isolated low power applications. In order to enhance the performance of these converters, planar transformers (PT) can be used that feature lower height, considerably lower leakage inductance, excellent thermal characteristics, repeatability, and manufacturing simplicity. Selecting...

The advancements in DC microgrids and the increase in distributed generation systems has led to a new trend towards the co-existence of multiple power converters from different sources (renewable, storage, etc.) supplying a variety of loads of different natures in a weak network. The loads can behave as passive loads (resistances) or be implemented...

This paper presents a fast selective harmonic current mitigation strategy for inverters with active power filter capabilities based in synchronous reference frames and two-degrees-of-freedom internal model controllers. The advantage of this control strategy over the conventional PI solution is a significant increase in the speed of harmonic detecti...

Flyback and Forward converters are two commonly used topologies for isolated low power applications. These converters are simple and cost effective and provide galvanic isolation which make them desirable for low power levels. In order to enhance the performance of these converters, planar transformers (PT) can be used that feature lower height, co...

The proliferation of PV installations across the globe has accelerated dramatically in the past decade covering home, rural, mobile, industrial, and utility scale applications. In all these cases, improving payback time and energy production for PV installations is a very complex design tradeoff that involves multiple variables such as irradiance f...

LLC resonant converters suffer from a start-up inrush current that may push power switches beyond the safe operating area. The conventional method of limiting the startup inrush current is to adopt the frequency decrement method; however, doing so results in the overdesign of magnetic components and the gate driver circuit, sluggish start-up respon...

In the past two decades, the operating voltage of PV installation has increased in order to reduce current ratings and system installation costs. Such a large number of PV panels in series (e.g. 1000 - 1500V systems) lead to wide variations of PV voltage due undesirable effects such as shading, soiling/dust, aging, and hot surface temperature. A pa...