New Fast and Accurate Steady-State Analysis Approach for Design, Optimization, and Simulation of General Power Converter Systems

• Author / Creator

  Sadri, Reza

• Accurate steady-state analysis of power converters are essential for converter design and optimization. Steady-state responses are also useful for component selection, loss calculation, identification of soft switching operation, and small signal modeling of power converters. Normally, a brute-force simulation is carried out to achieve the steady-state response; however, due to the zero initial conditions assumption, the simulation time in such methods is not efficient and fast. An accurate steady-state response, however, can be obtained if the initial conditions at the beginning of a switching cycle of the converter are accurately known. In this thesis, a non-iterative improved Laplace based theorem and enhanced state vector algorithm are proposed to calculate the steady-state initial conditions of the power converters.
  The proposed methods use the system’s switching time and state space representation to calculate the system’s initial vector. However, assuming the switching times as known inputs is not valid for all types of converters, such as the case of converters with uncontrolled switches or converters operating in discontinuous conduction mode. The proposed method is further modified to address this challenge by using the bisection approach to find the switching time of the converters that feature a monotonic function of the switching time. Then, a Switching Time Estimator (STE) is proposed to remove the monotonic function limitation on the type of converters since it uses a general-purpose simulator to find the uncontrolled events’ switching time.
  The thesis also discusses the extension of the proposed approaches to AC-DC and DC-AC converters, which are more challenging as multiple frequencies and variable amplitudes are involved. These challenges are overcome by modifying the period that the method will be applied and using a piecewise linear approximation of AC sources. Furthermore, the thesis discusses the steady-state analysis of the closed loop power converters. To calculate the initial vector of closed loop systems, the proposed Switching Time Estimator (STE) is modified to update the state of the controller.
  Several examples are provided in each chapter to demonstrate the speed of the proposed method compared to the existing approaches. In addition, the proposed method uses the calculated initial vector to achieve the steady-state waveforms of each converter, which are then compared to the Power Simulation (PSIM) generated waveforms to show the accuracy of the proposed method.

• Subjects / Keywords

  • Power Converter
  • Steady-State Analysis
  • Design
  • Optimization
  • Simulation

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-22b2-0j96

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.