amir Babazadeh - Academia.edu (original) (raw)
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HEC Montréal (Ecole des Hautes Etudes Commerciales)
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Papers by amir Babazadeh
2008 IEEE Power Electronics Specialists Conference, 2008
This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC convert... more This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC converters. The proposed controller is a combination of a standard constant-frequency PWM control in the vicinity of steady state and a bank of linear switching surface controllers (SSC) with slopes adaptively selected by a supervisor away from the reference. The supervisor selects the appropriate switching surface slope based on the capacitor current estimate and the quantized output error. A stability analysis using Lyapunov functions is presented. Experimental results for a 1.3 V, 10 A synchronous buck converter demonstrate near time optimal responses for a wide range of step load transients.
This paper analyzes the general problem of inductor current limitation in the time-optimal load t... more This paper analyzes the general problem of inductor current limitation in the time-optimal load transient response of a DC-DC buck converter. The concept of currentlimited, time-optimal control (CL-TOC) is introduced and compared to the previously reported unconstrained timeoptimal solutions. A fundamental tradeoff between maximum allowed current overshoot and voltage recovery time is recognized, and a set of design equations is developed which provide the engineer with the necessary analytical tools for the controller design. Furthermore, the minimum number of switching actions required to handle a generic current-limited TOC is determined, leading to the formulation of a minimumswitch CL-TOC concept. Two distinct approaches for minimumswitch digital CL-TOC are then introduced. The first method, which is an extension of a charge-balance approach, has the advantage of achieving the time-optimal switching sequence without the need for a prior knowledge of the output filter LC parameters. The second approach implements a near CL-TOC employing the switching surface concept and defining the current limitation in the state-space. Simulation and experimental results are provided to demonstrate the effectiveness of the approaches.
2008 IEEE Power Electronics Specialists Conference, 2008
This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC convert... more This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC converters. The proposed controller is a combination of a standard constant-frequency PWM control in the vicinity of steady state and a bank of linear switching surface controllers (SSC) with slopes adaptively selected by a supervisor away from the reference. The supervisor selects the appropriate switching surface slope based on the capacitor current estimate and the quantized output error. A stability analysis using Lyapunov functions is presented. Experimental results for a 1.3 V, 10 A synchronous buck converter demonstrate near time optimal responses for a wide range of step load transients.
This paper analyzes the general problem of inductor current limitation in the time-optimal load t... more This paper analyzes the general problem of inductor current limitation in the time-optimal load transient response of a DC-DC buck converter. The concept of currentlimited, time-optimal control (CL-TOC) is introduced and compared to the previously reported unconstrained timeoptimal solutions. A fundamental tradeoff between maximum allowed current overshoot and voltage recovery time is recognized, and a set of design equations is developed which provide the engineer with the necessary analytical tools for the controller design. Furthermore, the minimum number of switching actions required to handle a generic current-limited TOC is determined, leading to the formulation of a minimumswitch CL-TOC concept. Two distinct approaches for minimumswitch digital CL-TOC are then introduced. The first method, which is an extension of a charge-balance approach, has the advantage of achieving the time-optimal switching sequence without the need for a prior knowledge of the output filter LC parameters. The second approach implements a near CL-TOC employing the switching surface concept and defining the current limitation in the state-space. Simulation and experimental results are provided to demonstrate the effectiveness of the approaches.