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Current sharing control in multiphase converters is essential for stable and safe operation under variable conditions or applications. It is usually used to maintain equal or desired current sharing between converter phases. In conventional current sharing schemes, this requires the sensing and processing of each phase current through a current sharing/balancing controller, which adds complexity, size and cost to the converter design. In most cases, conventional schemes are usually based on achieving a preset current sharing ratio between phases (usually equal current value among different phases), assuming that the design of phases is known (or symmetric in the case of equal sharing ratio), which may not result in achieving the optimum efficiency. Moreover, the accuracy of achieving the preset current sharing ratio is sensitive to the current sensing accuracy in all phases, which requires careful and tedious calibration of sensing circuitries. Furthermore, when digital controller is used, in order to achieve equal current sharing or desired current distribution among different phases, more analog-to-digital converters (ADCs) are required to obtain digital information on equivalent phases' currents. In this paper, theoretical analysis results are presented to derive or prove a sensorless current sharing method. The analysis is further expanded to reveal the boundary conditions that result in not achieving the desired current sharing ratio. For example, it provides the conditions under which certain phases may carry negative current, resulting in overloading the other phases. The presented method is described and verified with experimental results from a proof of concept prototype based on digital controller implementation. Index Terms--Current sharing, dc-dc, digital control, multiphase, power converter, sensorless, Interleave.

Multiphase converters require a current-sharing loop to maintain equal or desired current sharing between phases or paralleled modules. The current-sharing loop is highly sensitive to current-sensing accuracy. In this letter, a method is presented to achieve auto-tuning of the current-sharing loop in multiphase converters while adaptively calibrating the current sensing based on power conversion efficiency. This is achieved without the need for a precise calibration reference or resistor and with no dependency on sensing accuracy. A digital controller implementation of the method is described and experimental results are obtained for a 0.84 V/30 A two-phase buck voltage regulator. Index Terms--Auto-tuning, calibration, converter, current sensing, current sharing, dc-dc, efficiency, multiphase, voltage regulator.

Voltage regulator (VR) efficiency improvement especially at light load currents is important in many applications including those that are battery powered and have energy consumption constrains. However, controlled steady-state and dynamic performance should be maintained while improving efficiency. In this paper, an analytical study of VR losses and voltage ripple deviation is presented and discussed, yielding to proposed control technique, namely 'pulse sliding' (PSL) control technique, which results in improved VR conversion efficiency with low and controlled voltage ripple and improved dynamic response. The proposed method and controller achieves the advantages of both variable frequency and fixed frequency controls and eliminates their disadvantages by utilizing information obtained from the inductor peak current, compensation error signal and capacitor current, resulting in an optimum nonlinear switching frequency modulation. PSL is compared to other control methods by both analysis and experiments. Experimental results highly agree with theoretical analysis. Index Terms--Adaptive, control, converter, dc-dc, dynamic response, efficiency, light load, performance, power management, ripple, voltage regulator (VR).

In a wireless power transfer (WPT) system, the efficiency decreases as the distance (DIS) or misalignment (MIS) between transmitter (Tx) coil and receiver (Rx) coil increases. As a result, the received load power is varying under different DIS/MIS conditions. Increasing the system efficiency and maintaining constant/stable output voltage/power are the major control targets in WPT system. This paper presents the evaluation of input power splitting (IPS) WPT system with multiple Tx coils (MTxWPT) in order to extend the area of output voltage/power stabilisation under varying DIS and MIS conditions, while improving the system efficiency at the same time. The control algorithm is realised by adaptively optimising the IPS multipliers α1 through αn to unequally split the input power (P1 through Pn) between multiple Tx coils. The maximum system efficiency point can be achieved with the optimum selection of IPS multipliers (α1 through αn). A DC-DC converter at Rx side is utilised to maintain the output voltage/power at a constant/stable value. Detailed sets of the model analysis and experimental prototype results are provided and discussed through the paper to evaluate the performance of the presented IPS MTxWPT system. [ABSTRACT FROM AUTHOR]

In a wireless power transfer (WPT) system, higher transmission efficiency and regulated output/load voltage/power are two major design targets or criteria of interest. This study presents the modelling, control design and stability evaluation of a reconfigurable WPT (R-WPT) system which can achieve constant receiver/load's voltage/power and realises transmission efficiency maximisation under varying transmission distances (DIS) and misalignment (MIS) conditions in addition to varying load conditions. The controller is realised to adaptively switch between different sizes of drive loops and load loops. As a result, the loop-coil coupling factors are optimised to realise transmission efficiency maximisation. The small-signal modelling of the complete closed-loop control R-WPT system is derived to evaluate the system stability during different configurations and different DIS/MIS conditions. Detailed sets of experimental results are provided and discussed throughout the study to give insight on the system modelling, operation and performance. [ABSTRACT FROM AUTHOR]

Single-inductor multiple-output (SIMO) switching dc–dc power converter architecture is a cost-effective alternative to multiple individual switching power converters solution in many power distribution system applications where multiple voltage rails are required at reduced cost. However, with multiple output voltage rails coupled to the same switching node, the SIMO power converters suffer from cross regulation between the multiple outputs, which complicates the closed-loop controller design of the SIMO converter and degrades regulation performance. In this paper, a power-multiplexed (PM) control scheme is proposed aiming to completely decouple the operations of multiple outputs from one another. The proposed PM control scheme results in eliminating the cross regulation among the multiple outputs while maintaining desired voltage regulation performance for each output under both steady-state and dynamic operations. Low-cost microcontroller or analog circuitries can be used to implement the proposed controller. Experimental proof of concept prototype results verify the feasibility and advantages of the proposed controller. [ABSTRACT FROM PUBLISHER]