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For switched mode power converters, boundary conduction mode (BCM) operation is an attractive alternative to improve the bandwidth, overall size, and efficiency. In this article, a sensorless ripple current mode (SRCM) controller is proposed to achieve inductor-deviation-tolerant BCM operation for boost converter. Compared to conventional approaches with current sensing or ZCD, the proposed controller relies on a digital algorithm to ensure consistent BCM operation. The algorithm calculates on/off durations of the main switch so that the inductor current valley value converges to zero. The convergence process is proved by a damped current model with considerations of parasitics and output voltage ripple. Since the convergence is not related to the inductor value, the SRCM controller achieves inductor-deviation-tolerant BCM operation. Furthermore, to improve the power efficiency, an optimal transition condition and a compensation time are adopted to achieve valley switching (VS). Finally, both consistent BCM operation and VS are achieved by the proposed control strategy. Simulations and experimental results prove that the controller effectively improves the closed-loop stability, the robustness to inductor deviation, and the power efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a linearized discrete charge balance (LDCB) control strategy is proposed for buck converter operating in discontinuous conduction mode (DCM). For DC-DC power converters, discrete charge balance (DCB) control is an attractive approach to improve the output voltage transient response. However, as a non-linear control strategy, the algorithm is complex, which is difficult for implementation. To reduce the complexity, this paper proposes the LDCB control strategy that is derived through linearizing conventional DCB controller. By deriving the differential functions of the DCB control algorithm, the small signal relationship between the input and output of DCB controller is explored. Furthermore, based on the relationship, the LDCB controller is formed through three parallel feed loops to the duty ratio. As a linear control approach, the achieved LDCB controller is greatly simplified for implementation. This not only saves the hardware cost, but also reduces the calculation lag, which provides potential to improve the switching frequency. Besides, since the LDCB controller shares the same small signal model as that of DCB controller, it achieves similar control loop bandwidth and transient performance. Effectiveness of the proposed LDCB control is verified by zero/pole plots, transient analyses and experimental results. [ABSTRACT FROM AUTHOR]

Abstract: This paper develops a novel dynamic framed slotted ALOHA (DFSA) algorithm based on Bayesian estimation to improve the throughput of the radio frequency identification (RFID) system. At first, four types of anti-collision algorithms for tag identification are analyzed. Then, the proposed DFSA based on Bayesian estimation is deduced and introduced. Compared with the conventional DFSA algorithms, this algorithm takes advantage of the evidence in previous frames as the a priori information of the current frame which can end up with more precise estimation of tag number and rational frame length adjustment. Finally, the common simulation tool from Matlab is used to demonstrate the effectiveness of the proposed new algorithm for the average throughput improvements of the RFID system. [Copyright &y& Elsevier]