Jaber A. Abu Qahouq

Novel Current Sharing Schemes for Multiphase Converters with Digital Controller Implementation

Multiphase converters require a current sharing loop to maintain equal or desired current sharing between phases or paralleled modules. Conventional current sharing schemes are based on sensing each phase current to provide the current information to the control loop. Such schemes have disadvantages including the fact that they operate to generate a pre-set sharing ratio that is independent of converter efficiency value, they are highly affected by the sensing accuracy of each phase, and they require large associated sensing circuitries and off-line calibration. In this paper, new efficiency based current sharing concepts and schemes are proposed and discussed to eliminate or reduce the disadvantages of conventional schemes. The proposed concepts are based on dynamically maximizing the efficiency (minimizing power losses) of the converter to achieve the optimum current sharing ratio. They also provide schemes that are independent of sensing accuracy and require a reduced number of sensors and associated circuitries. The proposed schemes can be used for current sharing as stand-alone designs or can be combined with conventional schemes to achieve online current sharing loop calibration. Digital controller implementation is presented utilizing flexibility and other advantages of digital controllers. Experimental results are presented to support the theoretical analysis.

Highly Efficient VRM For Wide Load Range with Dynamic Non-Uniform Current Sharing

Multiphase converters are widely used especially in powering high-current loads. These converters are conventionally designed with symmetric phases and equal/uniform current sharing. This paper presents a multiphase VRM utilizing the concept of dynamic non-uniform current sharing between non-uniform phases. It is shown in this paper that high efficiency conversion can be achieved over wider load range with non-uniform phase design in multiphase converters and by utilizing the control scheme of dynamically varied non-uniform current sharing ratio between the interleaved phases. It is also shown that the proposed concept does not necessarily cause the increase in the size and cost of VRM design. The concept can be further expanded to the designs of other power stages such as AC-DC and PFC converters, bus converters and isolated or non-isolated converters. Theoretical and experimental results are provided in this paper, and they are compared with conventional symmetric designs with uniform current sharing.

Reconfigurable Magnetic Resonance-Coupled Wireless Power Transfer System

This paper presents a method for a reconfigurable magnetic resonance-coupled wireless power transfer (R-MRC-WPT) system in order to achieve higher transmission efficiency under various transmission distance and/or misalignment conditions. Higher efficiency, longer transmission distance, and larger misalignment tolerance can be achieved with the presented R-MRC-WPT system when compared to the conventional four-coil MRC-WPT (C-MRC-WPT) system. The reconfigurability in the R-MRC-WPT system is achieved by adaptively switching between different sizes of drive loops and load loops. All drive loops are in the same plane and all load loops are also in the same plane; this method does not require mechanical movements of the drive loop and load loop and does not result in the system volume increase. Theoretical basis of the method for the R-MRC-WPT system is derived based on a circuit model and an analytical model. Results from a proof-of-concept experimental prototype, with transmitter and receiver coil diameter of 60 cm each, show that the transmission efficiency of the R-MRC-WPT system is higher than the transmission efficiency of the C-MRC-WPT system and the capacitor tuning system for all distances up to 200 cm (~3.3 times the coil diameter) and for all lateral misalignment values within 60 cm (one coil diameter).

Power Converter with Gradient Power Architecture and Non-Uniform Current Sharing

A gradient power architecture concept with non-uniform current/power sharing is presented in this paper. A voltage regulator with this concept is designed, analyzed, and experimented. This scheme results in improved efficiency especially at lighter loads and the ability to control steady-state and dynamic performance especially when some of the phases are turned OFF at lighter loads

MPPT Control and Architecture for PV Solar Panel with Sub-Module Integrated Converters

Photovoltaic (PV) solar systems with series-connected module integrated converters (MICs) are receiving increased attention because of their ability to create high output voltage while performing local maximum power point tracking (MPPT) control for individual solar panels, which is a solution for partial shading effects in PV systems at panel level. To eliminate the partial shading effects in PV system more effectively, sub-MICs are utilized at the cell level or grouped cell level within a PV solar panel. This study presents the results of a series-output-connection MPPT (SOC-MPPT) controller for sub-MIC architecture using a single sensor at the output and a single digital MPPT controller (sub-MIC SOC-MPPT controller and architecture). The sub-MIC SOC-MPPT controller and architecture are investigated based on boost type sub-MICs. Experimental results under steady-state and transient conditions are presented to verify the performance of the controller and the effectiveness of the architecture.

Adaptive Controller with Mode Tracking and Parametric Estimation

Digital controller algorithms are presented in this paper which allows detecting DCM and CCM operations without instantaneous or cycle by cycle sensing and sampling of inductor current. The presented control scheme also allows the estimation on output inductor value, the peak inductor current value and other information on converter operations. The objective is to estimate all of this information from the input current with low speed sensing without feeding any constants to the controller. The presented controller does not depend on sensing the input voltage, the load current, or any other information of the converter design. The presented algorithms are discussed and analyzed.

A constant switching frequency coupled-inductor VR with improved light load efficiency

Coupled-inductor voltage regulator (VR) topology is one candidate for high-efficiency VR applications with stringent steady-state and dynamic requirements. This paper presents a coupled inductor voltage regulator operating at a fixed switching frequency with improved light load efficiency. The proposed VR concept is discussed, analyzed and experimentally verified.

A Converter with Fixed Switching Frequency Adaptive Multi-Mode Control Scheme

A multi-mode adaptive control scheme to achieve high conversion efficiency over wide load range is presented in this paper. The presented controller results in improved efficiency while operating at a fixed switching frequency which guarantees maintained steady-state and dynamic performance at all load conditions. This is achieved by operating in three or more different modes in a reconfigurable topology structure as a function of the load to achieve a reduced total conversion loss which reduces energy usage and extends battery life. Theoretical analysis for the proposed control scheme and comparison with state of the art schemes are presented and validated with a 1.5V /50W proof of concept experimental prototype results.