Dragan Maksimovic

Dragan Maksimovic
University of Colorado Boulder | CUB · Department of Electrical, Computer, and Energy Engineering (ECEE)

PhD

About

481
Publications
137,643
Reads
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23,341
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Introduction
Dragan Maksimovic currently works at the Department of Electrical, Computer, and Energy Engineering (ECEE), University of Colorado Boulder.

Publications

Publications (481)
Conference Paper
Full-text available
Mismatch power losses in photovoltaic (PV) systems can be reduced by the use of distributed power electronics at the module or submodule level. This paper presents an experimentally validated numerical model that can be used to predict power production with distributed maximum power point tracking (DMPPT) down to the cell level. The model allows th...
Article
Full-text available
This paper describes a complete digital PWM controller IC for high-frequency switching converters. Novel architecture and configurations of the key building blocks are A/D converter, compensator, and digital pulse-width modulator, are introduced to meet the requirements of tight output voltage regulation, high-speed dynamic response, and programmab...
Article
This article presents a new state-of-charge (SOC) balancing method with parallel and series output connected battery power modules (BPMs) in an active battery management system (BMS.) To increase both the battery pack and system-level modularity, the BMS controls the average SOC of the entire battery pack by regulating the input currents of all BPM...
Article
Levelized cost of energy (LCOE) is a commonly used metric to assess the cost-to-benefit ratio over the lifetime of an energy resource, such as photovoltaics (PV); however, power electronics engineers tend to rely on metrics such as efficiency and power density, which do not guarantee lifetime cost optimality. Recent work has shown that an LCOE-focu...
Article
This paper is focused on modeling and design optimization of high-current-ripple planar inductors in liquid-cooled high-power applications, such as electric-vehicle drivetrain systems, where efficiency and power density are the key performance metrics. The planar-inductor optimization is facilitated by innovations in computationally efficient and a...
Article
This paper presents an online efficiency optimization strategy for a digitally controlled, wide operating range silicon-carbide (SiC) based boost converter with bidirectional power flow. The proposed strategy minimizes switching losses at any given operating point by adjusting the converter switching frequency and dead times to optimally set the pe...
Article
Parallel output connected converters have been widely investigated with a focus on equal current and power sharing. However, parallel output connected battery power modules (BPMs) require unequal currents to enable state-of-charge (SOC) control in active battery management systems (BMS.) This paper presents simple differential input current regulat...
Conference Paper
This paper is focused on a composite step-down dc-dc converter architecture capable of operating efficiently over wide input voltage range. The composite architecture consists of a transformerless fixed-ratio stage (DCX) and a non-inverting buck-boost stage, which provides regulation while processing a relatively small fraction of the load power. T...
Article
This article is focused on the thermal design and three-dimensional (3-D) package optimization of planar magnetic components (PMCs), including transformers and inductors for application in an electric vehicle composite boost dc–dc converter. Each PMC comprises electrical windings in printed circuit board (PCB) form in combination with a ferrite cor...
Conference Paper
Full-text available
This paper presents a resonant dc-dc converter capable of providing load-independent output current without the need for active current control. This converter comprises an LC 3 L resonant tank, with inductance and capacitance values selected based on a new design methodology that achieves two objectives: 1) the converter’s output current is indepe...
Article
Full-text available
This article presents a two-stage automotive LED driver architecture delivering independently regulated output currents to multiple LED strings. The system consists of a multiphase noninverting buck–boost front-end stage, which allows for a wide battery voltage range, followed by high-frequency immittance-network-based LCL-T resonant converters, wh...
Article
This paper presents output voltage sharing among series output connected battery power modules (BPMs) in plug-and-play (PnP) DC microgrids with a wide bus voltage range. The system provides active cell balancing and interfaces cells to the bus voltage through series output connected BPMs. A cell current sensor is utilized to achieve both state-of-c...
Article
This paper presents analysis, properties and systematic synthesis of a new class of hybrid dc-dc converters named Transformerless Stacked Active Bridge (TSAB) converters. TSAB converters, which are obtained from switched-capacitor (SC) converters by insertion of small ac inductors, inherit advantages of parent SC converters together with conversion...
Article
Complex electronic systems often require a power distribution architecture that provides multiple, separate voltage domains for various subsystem loads such as microprocessor cores, interface, memory, analog, and radio frequency components. The multiple point-of-load regulated voltages are typically generated using multiple dc-dc converters operati...
Article
Full-text available
This paper introduces an immittance network based wide range LCL-T resonant dc-dc converter where two control variables, a phase shift between two inverter half bridges and a phase shift between inverter and rectifier half bridges, are utilized to achieve output current regulation while minimizing losses over wide ranges of input and output voltage...
Chapter
Part VI of this text deals with a class of converters whose operation differs significantly from the PWM converters covered in Parts I to V. Resonant power converters [272, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329] co...
Chapter
Magnetics are an integral part of every switching converter. Often, the design of the magnetic devices cannot be isolated from the converter design. The power electronics engineer must not only model and design the converter, but must model and design the magnetics as well. Modeling and designing of magnetics for switching converters is the topic o...
Chapter
This chapter treats the design of magnetic elements such as filter inductors, using the geometrical constant (Kg) method. With this method, the maximum flux density Bmax is specified in advance, and the element is designed to attain a given copper loss.
Chapter
Converter systems invariably require feedback. For example, in a typical dc–dc converter application, the output voltage v(t) must be kept constant, regardless of changes in the input voltage vg(t) or in the effective load resistance R. This is accomplished by building a circuit that varies the converter control input [i.e., the duty cycle d(t)] in...
Chapter
We have seen in previous chapters that the switching elements of the buck, boost, and several other dc–dc converters can be implemented using a transistor and diode. One might wonder why this is so, and how to realize semiconductor switches in general. These are worthwhile questions to ask, and switch implementation can depend on the power processi...
Chapter
In all switching converters, the output voltage v(t) is a function of the input line voltage vg(t), the duty cycle d(t), and the load current iload(t), as well as the converter circuit element values. In a dc–dc converter application, it is desired to obtain a constant output voltage v(t) = V , in spite of disturbances in vg(t) and iload(t), and in...
Chapter
Part IV of this text develops analytical tools needed to understand and design larger power electronic systems. It builds on the basic modeling and analysis techniques developed in Part II to analyze and simulate complex feedback circuits, including those having input EMI filters, current-mode control, or digital control.
Chapter
So far, we have discussed duty ratio control of PWM converters, in which the converter output is controlled by direct choice of the duty ratio d(t). We have therefore developed expressions and small-signal transfer functions that relate the converter waveforms and output voltage to the duty ratio. This direct duty ratio control is sometimes called...
Chapter
In the design methods of the previous chapter, copper loss Pcu and maximum flux density Bmax are specified, while core loss Pfe is not specifically addressed. This approach is appropriate for a number of applications, such as the filter inductor in which the dominant design constraints are copper loss and saturation flux density. However, in a subs...
Chapter
To obtain low ac line current THD, the passive techniques described in the previous chapter rely on low-frequency transformers and/or reactive elements. The large size and weight of these elements are objectionable in many applications. This chapter covers active techniques that employ converters having switching frequencies much greater than the a...
Chapter
We have already analyzed the operation of a number of different types of converters: buck, boost, buck–boost, Ćuk, voltage-source inverter, etc. With these converters, a number of different functions can be performed: step-down of voltage, step-up, inversion of polarity, and conversion of dc to ac or vice-versa.
Chapter
Circuit averaging is another well-known technique for derivation of converter equivalent circuits. Rather than averaging the converter state equations, with the circuit averaging technique we average the converter waveforms directly. All manipulations are performed on the circuit diagram, instead of on its equations, and hence the circuit averaging...
Chapter
Sections 8.1 to 8.3 discuss techniques for analysis and construction of the Bode plots of the converter transfer functions, input impedance, and output impedance predicted by the equivalent circuit models of Chap. 7. For example, the small-signal equivalent circuit model of the buck–boost converter is illustrated in Fig. 7.18c. This model is reprod...
Chapter
When the ideal switches of a dc–dc converter are implemented using current-unidirectional and/or voltage-unidirectional semiconductor switches, one or more new modes of operation known as discontinuous conduction modes (DCM) can occur. The discontinuous conduction mode arises when the switching ripple in an inductor current or capacitor voltage is...
Chapter
Middlebrook’s Extra Element Theorem (EET) is a powerful technique of Design-Oriented Analysis that aids in the analysis of complex circuits and systems, with the goal of deriving tractable equations that are useful for design. As with the Feedback Theorem of Chap. 13, it is based on linear superposition and the null double injection analysis techni...
Chapter
Digital control methods and digital controllers based on general-purpose or dedicated microcontrollers, digital signal processors (DSP’s), or programmable logic devices have been widely adopted in power electronics applications at relatively high-power levels, including motor drives or grid-tied three-phase inverters and rectifiers. In these applic...
Chapter
It is nearly always required that a filter be added at the power input of a switching converter. By attenuating the switching harmonics that are present in the converter input current waveform, the input filter allows compliance with regulations that limit conducted electromagnetic interference (EMI). The input filter can also protect the converter...
Chapter
Let us now consider the basic functions performed by a switching converter, and attempt to represent these functions by a simple equivalent circuit. The designer of a converter power stage must calculate the network voltages and currents, and specify the power components accordingly. Losses and efficiency are of prime importance. The use of equival...
Chapter
In addition to the resonant circuits introduced in Chap. 10.1007/978-3-030-43881-4_22, there has been much interest in reducing the switching loss of the PWM converters of the previous chapters. Several of the more popular approaches to obtaining soft switching in buck, boost, and other converters are discussed in this chapter.
Chapter
Rectification used to be a much simpler topic. A textbook could cover the topic simply by discussing the various circuits, such as the peak-detection and inductor-input rectifiers, the phase-controlled bridge, polyphase transformer connections, and perhaps multiplier circuits. But recently, rectifiers have become much more sophisticated, and are no...
Article
Full-text available
In high-frequency inductors, ac winding losses are affected by skin and proximity effects, including uneven current distribution due to fringing magnetic fields around air gaps. It is well known that fringing effects can be mitigated using distributed air gaps. This paper is focused on an orthogonal-airgap approach, which is a distributed air-gap t...
Article
This paper introduces a megahertz-frequency resonant dc-dc converter that inherently achieves a load-independent output current while maintaining high efficiency across a wide output voltage range. These properties make the proposed converter well-suited for automotive light-emitting diode (LED) driver applications, where a varying number of LEDs n...
Book
Fundamentals of Power Electronics, Third Edition, is an up-to-date and authoritative text and reference book on power electronics. This new edition retains the original objective and philosophy of focusing on the fundamental principles, models, and technical requirements needed for designing practical power electronic systems while adding a wealth...
Article
This paper is focused on a PV system architecture based on series-connected low-voltage ac (LVAC) microinverters. In contrast to standard microinverters, LVAC microinverters do not require high step-up conversion stages, which leads to potentials for improved efficiency and reduced cost. The paper proposes a distributed autonomous control strategy...