CU-Boulder ECEN 5797 - Converter Transfer Functions (35 pages)

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Chapter 8 Converter Transfer Functions 8 1 Review of Bode plots 8 1 1 8 1 2 8 1 3 8 1 4 8 1 5 8 1 6 8 1 7 8 1 8 Single pole response Single zero response Right half plane zero Frequency inversion Combinations Double pole response resonance The low Q approximation Approximate roots of an arbitrary degree polynomial 8 2 Analysis of converter transfer functions 8 2 1 Example transfer functions of the buck boost converter 8 2 2 Transfer functions of some basic CCM converters 8 2 3 Physical origins of the right half plane zero in converters Fundamentals of Power Electronics 1 Chapter 8 Converter Transfer Functions Converter Transfer Functions 8 3 Graphical construction of converter transfer functions 8 3 1 8 3 2 8 3 3 8 3 4 Series impedances addition of asymptotes Parallel impedances inverse addition of asymptotes Another example Voltage divider transfer functions division of asymptotes 8 4 Measurement of ac transfer functions and impedances 8 5 Summary of key points Fundamentals of Power Electronics 2 Chapter 8 Converter Transfer Functions The Engineering Design Process 1 Specifications and other design goals are defined 2 A circuit is proposed This is a creative process that draws on the physical insight and experience of the engineer 3 The circuit is modeled The converter power stage is modeled as described in Chapter 7 Components and other portions of the system are modeled as appropriate often with vendor supplied data 4 Design oriented analysis of the circuit is performed This involves development of equations that allow element values to be chosen such that specifications and design goals are met In addition it may be necessary for the engineer to gain additional understanding and physical insight into the circuit behavior so that the design can be improved by adding elements to the circuit or by changing circuit connections 5 Model verification Predictions of the model are compared to a laboratory prototype under nominal operating conditions The model is refined