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Load-independent output with zero-phase-angle (ZPA) input is desirable in wireless inductive power transfer (IPT) converters for effective power delivery, but it usually greatly relies on the parameters of the loosely coupled transformer, normally fixed or constrained by space. Thus, customizable outputs cannot be readily achieved unless a new transformer is redesigned. In this article, we elaborate the rather complex relationships among compensation parameters, customizable load-independent-voltage (LIV) outputs with ZPA input, power efficiency, and overall compensation capacitance cost of the series/series-parallel (S/SP) IPT converter. We present a cost-effective compensation design to free the customization of LIV outputs from a parameter-constrained loosely coupled transformer, with optimization between efficiency enhancement and overall compensation capacitance cost. We conducted the proposed design supported by experimental results in S/SP IPT converters with an identical loosely coupled transformer and various sets of compensation capacitors. Compared with a conventional design, the proposed design provides custom ranges of LIV outputs in both a weak and a relatively strong coupling condition, with over 5.9% and 5% efficiency improvement, respectively. The overall compensation capacitance can also be reduced by up to 37% and 21.5%, respectively. [ABSTRACT FROM AUTHOR]

Digital power management systems allow power converters to operate with multiple changes in voltage reference. This asks for a new paradigm that shifts from achieving faster response to achieving best efficiency during multiple transients, with transient being eventually time constrained. State-space-based design of the control system fits perfectly this goal, since it is a time-domain design tool. It can further be enhanced with a linear quadratic regulator (LQR) optimization, configured with converter loss equation as cost function. The LQR mathematics guarantees a solution to the algebraic Riccati equation that produces the best system efficiency for the converter system during multiple transients. This article documents the design of the LQR control system having converter loss as a cost function and demonstrates the advantages of this method. The closed-loop control software yields very simple, running with a 250 kHz sampling frequency capability on a general use Microchip microcontroller platform. While a loss reduction of 2.5% is demonstrated by experiment in our setup, the advantage depends on the actual system work profile. [ABSTRACT FROM AUTHOR]

Aiming to improve the performance features of conventional two-level dual-active-bridge (DAB) converters, this paper presents a three-level neutral-point-clamped (NPC) DAB dc–dc converter. A general modulation pattern is initially defined, the dc-link capacitor voltage balancing is analyzed in detail, and a proper balancing control is designed. Then, a set of decoupled optimization problems is formulated as a function of the available modulation degrees of freedom to minimize the predominant converter losses. Finally, a simple and practical specific modulation strategy is provided, resembling the optimum solutions. The good performance of the proposed three-level NPC DAB converter operated with the proposed modulation strategy and voltage balancing control is verified through simulation and experiments. The capacitor voltage balancing can be guaranteed for all operating conditions. In addition, it is concluded that the multilevel topology provides benefits compared with the conventional two-level DAB converter. [ABSTRACT FROM PUBLISHER]

Efficiency optimization of induction motor (IM) drives is a major subject based on these drives' extensive use in the industry. Among the different proposed methods, a model- based approach (MBA) seems to be the fast one. However, this method needs the motor parameters that must be correctly identified. On the other hand, a search-based approach (SBA) is a parameter-independent method but needs a greater convergence time. In this paper, a novel model-based loss-minimization approach is presented, which is combined with a backstepping direct torque control of the IM drive. An improved search-based method for efficiency optimization is also introduced. The proposed controller is realized in the stationary reference frame and has a fast-tracking capability of rotor flux and electromagnetic torque. Moreover, a sliding.mode rotor-flux observer is introduced, which is employed for simultaneous determination of rotor-flux space vector, rotor speed, and rotor time constant. The proposed control idea is experimentally implemented in real time using a field-programmable gate-array board synchronized with a personal computer. Simulation and experimental results are finally presented to verify the effectiveness of the method proposed. [ABSTRACT FROM AUTHOR]

This paper presents a new approach of optimizing the efficiency of induction-motor drives through minimizing the copper and core losses. The induction-machine model, which accounts for the varying core-loss resistance and saturation dependent magnetizing inductance, uses natural and reference frame independent quantities as state variables. Utilization of the non- linear geometric control methodology of input—output linearization with decoupling permits the implementation of the control in the stationary reference frame. This approach eliminates the need of synchronous reference transformation and flux alignment required in classical vector control schemes. The new efficiency optimizing formulation yields a reference rotor flux, which ensures a minimum loss and yields an improved efficiency of the drive system especially when driving part load. The proposed scheme and its advantages are demonstrated both by computer simulations and some experimental results for motor speed control. [ABSTRACT FROM AUTHOR]