Brushless DC motor modeling and optimal control: a cardiovascular application
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The increasing use of Ventricular Assist Devices (VADs) in patients with weak or failing hearts has driven a need for more thorough analysis of VAD design, control methods, and cardiovascular dynamic effects. In recent years, studies have shown the potential of applying formal optimization methods to VAD actuation in order to reduce power consumption or improve pump output. This thesis continues the use of formal optimization methods as well as digital analysis using the brushless DC (BLDC) motors within the TORVAD(TM), designed by Windmill Cardiovascular Systems, Inc. (WCS), as a basis. To begin the optimization, a parameterized model of the BLDC motor system has been developed and combined with a lumped parameter model of the cardiovascular system. The combined system is then digitally analyzed under varying rates of TORVAD(TM) motor controller frequencies to determine the minimum frequency at which the system will remain stable and minimize detrimental physiological effects. Formal optimization methods are then introduced and implemented on the combined motor and cardiovascular system model. The output of the optimization is a reference trajectory that minimizes average motor power consumption. This trajectory, along with the results from the digital analysis, provides a more robust examination on the combined motor and cardiovascular system.