Lecture

Mod-04 Lec-12 Low switching frequency PWM -- II

Continue your journey into low switching frequency PWM techniques. Examine detailed methodologies for selective harmonic elimination and their application in minimizing unwanted harmonics in power systems. Learn about the THD optimized PWM technique and how it helps achieve better performance in power converters.

Understand the significance of offline PWM strategies in reducing harmonic distortion and improving the efficiency of power electronic systems.


Course Lectures
  • Explore the foundational concepts of electronic switches crucial for power electronic converters. Understand the different types of switches including bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and insulated-gate bipolar transistors (IGBTs). Learn about their characteristics, operating principles, and applications in various power conversion systems.

    Gain insights into the working mechanisms of these switches and their significance in enhancing the efficiency of power converters. Additionally, discover the role of electronic switches in managing energy flow and their impact on the overall performance of power electronic systems.

  • Delve into the world of DC-DC converters and comprehend their significance in power electronics. Learn about various topologies such as buck, boost, and buck-boost converters. Explore their operational principles, design considerations, and applications in modern electronic devices.

    • Understand the working of buck converters for voltage step-down applications.
    • Explore boost converters for voltage step-up requirements.
    • Analyze the combined functionality of buck-boost converters for versatile applications.

    Additionally, study the efficiency and performance metrics that influence the selection of DC-DC converters in different electronic systems.

  • Investigate the transformation of DC to AC power through DC-AC converters, also known as inverters. Understand their importance in renewable energy systems and various industrial applications. Study the working principles of single-phase and three-phase inverters, emphasizing their role in converting stored DC power into usable AC power for different applications.

    Examine the different inverter topologies, including voltage source inverters (VSI) and current source inverters (CSI), and learn how they help in achieving efficient power conversion while maintaining power quality and reliability.

  • Gain a comprehensive understanding of multilevel converters and their significance in modern power electronic systems. Explore the first part of this topic, focusing on diode-clamped and flying capacitor multilevel converters. Examine their operational principles, benefits, and implementation challenges.

    Learn how multilevel converters enhance power quality, reduce switching losses, and provide higher voltage handling capabilities, making them ideal for high-power applications. Discover the unique attributes of diode-clamped and flying capacitor topologies and their application in various industrial sectors.

  • Continue your exploration of multilevel converters with a focus on cascaded-cell converters. Understand their operational mechanisms, advantages, and how they differ from other multilevel converter topologies. Study their role in achieving higher voltage levels and improved power quality in various industrial applications.

    Learn about the design and implementation challenges associated with cascaded-cell converters and how they are addressed in practical scenarios. Discover their potential in renewable energy systems, electric vehicles, and other high-demand power applications.

  • Learn about the diverse applications of voltage source converters (VSC) in the first part of this module. Explore their role in motor drives, where they enable variable speed control and enhance operational efficiency. Understand how VSCs serve as active front-end converters in maintaining power factor and reducing harmonics in power systems.

    Additionally, delve into their use in reactive power compensation, providing stability to power grids, and in active power filtering, where they help mitigate harmonic distortion and improve power quality.

  • Expand your understanding of voltage source converters (VSC) applications in this second part. Examine their use as reactive power compensators, where they enhance grid stability and efficiency. Understand their role as active power filters in reducing harmonic distortion and improving the overall power quality of electrical systems.

    Learn about the implementation of VSCs in various industrial applications, including renewable energy systems and smart grids, where they optimize power flow and ensure efficient energy distribution.

  • In this third part, continue exploring the diverse applications of voltage source converters (VSC). Discover their critical role in the integration of renewable energy sources into the power grid, ensuring stability, and efficient energy management. Explore their use in smart grids and distributed energy resources, enhancing grid intelligence and adaptability.

    Understand how VSCs contribute to load balancing, voltage regulation, and loss reduction in modern power systems, making them an integral component of advanced power electronics.

  • Explore the fundamental purpose of pulsewidth modulation (PWM) techniques in power electronic converters. Understand how PWM helps in controlling the fundamental voltage and mitigating harmonics in power systems. Learn about the Fourier series and its application in analyzing harmonic voltages within electrical machines.

    Examine the adverse effects of harmonic voltages, including line current distortion, increased losses, and pulsating torque in motor drives, and discover PWM's role in overcoming these challenges.

  • Continue your exploration of the purpose of pulsewidth modulation (PWM) in power electronic converters. Delve deeper into the control of fundamental voltage and the mitigation of harmonics. Study the implementation of machine models for harmonic voltages and the strategies to mitigate their undesirable effects.

    Learn about the various challenges posed by harmonic voltages, such as increased losses and pulsating torque, and how PWM techniques are employed to address these issues effectively.

  • Discover the implementation of PWM techniques at low switching frequencies. Study the square wave operation of voltage source inverters and the use of PWM with limited switching angles per cycle. Explore concepts like equal voltage contours and selective harmonic elimination to optimize performance.

    Understand the significance of off-line optimized PWM in reducing total harmonic distortion (THD) and its application in various power electronic systems.

  • Continue your journey into low switching frequency PWM techniques. Examine detailed methodologies for selective harmonic elimination and their application in minimizing unwanted harmonics in power systems. Learn about the THD optimized PWM technique and how it helps achieve better performance in power converters.

    Understand the significance of offline PWM strategies in reducing harmonic distortion and improving the efficiency of power electronic systems.

  • Explore the concept of selective harmonic elimination in PWM techniques. Understand its importance in reducing unwanted harmonics and enhancing the performance of power electronic systems. Learn about the methodologies involved in implementing selective harmonic elimination and its impact on system efficiency.

    Discover how this technique helps in achieving optimal performance by minimizing the total harmonic distortion (THD) in power converters.

  • Learn about the off-line optimized pulsewidth modulation technique and its significance in power electronic systems. Understand how it helps in minimizing total harmonic distortion (THD) and improving overall system efficiency.

    Explore the implementation strategies of off-line optimized PWM and its application in various power converters, emphasizing its role in enhancing performance and reducing harmonic content.

  • Dive into the sine-triangle pulsewidth modulation technique and its application in power electronic converters. Understand the average pole voltages concept and the process of sinusoidal modulation. Learn about third harmonic injection and its role in improving the modulation index and reducing harmonic distortion.

    Explore the implementation of continuous PWM and bus-clamping (discontinuous) PWM strategies, focusing on their advantages and applications in various converter topologies.

  • Discover the harmonic injection pulsewidth modulation technique and its significance in power electronic converters. Understand how it enhances the modulation index and reduces harmonic distortion by injecting specific harmonics into the modulation process.

    Learn about the benefits of harmonic injection PWM in improving power quality and achieving better performance in various converter topologies.

  • Explore the concept of bus-clamping pulsewidth modulation and its application in power electronic converters. Understand how this technique helps in reducing switching losses and enhancing efficiency by clamping the bus voltage during specific intervals of the modulation cycle.

    Learn about the advantages of bus-clamping PWM in various converter topologies and its role in improving the overall performance and reliability of power electronic systems.

  • Delve into the triangle-comparison based PWM technique for three-phase inverters. Understand its significance in achieving balanced output voltages and reducing harmonic distortion in multi-phase systems.

    Learn about the implementation strategies of triangle-comparison based PWM and its application in enhancing the performance and efficiency of three-phase power electronic systems.

  • Understand the concept of space vectors and their application in pulsewidth modulation techniques for power electronic converters. Learn about the transformation of three-phase quantities into space vectors and their significance in achieving better control and performance.

    Explore the advantages of space vector modulation in reducing harmonic distortion and improving the efficiency of power electronic systems.

  • Examine the conventional space vector pulsewidth modulation technique and its significance in power electronic converters. Understand how it provides a systematic approach to achieve optimal switching sequences and reduce harmonic distortion.

    Learn about the benefits of conventional space vector PWM in enhancing the performance and efficiency of various power electronic systems.

  • Discover the space vector based bus-clamping pulsewidth modulation technique and its application in power electronic converters. Understand how it combines the benefits of space vector modulation and bus-clamping strategies to reduce switching losses and improve performance.

    Learn about the implementation of space vector based bus-clamping PWM in various converter topologies and its role in enhancing the efficiency and reliability of power electronic systems.

  • Explore the advanced space vector based bus-clamping pulsewidth modulation technique and its application in power electronic converters. Understand how it extends conventional methods to achieve even greater efficiency and performance improvements in power systems.

    Learn about the advanced strategies employed in this technique and their impact on reducing harmonic distortion and improving the reliability of power electronic systems.

  • This module delves into the harmonic analysis of various pulse width modulation (PWM) techniques. It covers the impact of harmonics on power quality, including:

    • Fundamental frequency components and their significance in PWM.
    • Different harmonic orders and their effects on system performance.
    • Methods to mitigate harmonic distortion in PWM strategies.

    By the end of this module, students will understand how to analyze and optimize PWM techniques to minimize unwanted harmonic effects in power converters.

  • In this module, students will analyze the RMS line current ripple using the concept of stator flux ripple in induction motor drives. The following aspects will be covered:

    • Understanding stator flux ripple and its relation to current ripple.
    • Mathematical modeling of RMS line current ripple.
    • Real-world implications of current ripple on motor efficiency and performance.

    This module equips students with the analytical tools to evaluate and manage current ripple effectively in power electronic systems.

  • This module focuses on the evaluation of RMS line current ripple, emphasizing its relationship with stator flux ripple. Key topics include:

    • Calculating RMS values for line current ripple.
    • The impact of ripple on overall system performance.
    • Comparison of theoretical and practical ripple values in motors.

    Students will gain insights into the significance of current ripple in induction motor applications and how to effectively manage it.

  • This module covers the analysis and design of PWM techniques, specifically focusing on line current ripple. Students will explore:

    • Design considerations for reducing line current ripple.
    • Techniques for optimizing PWM to improve current quality.
    • Case studies demonstrating effective PWM design strategies.

    The knowledge gained will enable students to implement design strategies that minimize ripple and enhance overall inverter performance.

  • This module investigates the instantaneous and average DC link current in voltage source inverters. Key learning points include:

    • Understanding the relationship between AC input and DC link currents.
    • Analysis of current ripple in the DC link.
    • Implications for inverter design and operation.

    Students will learn to evaluate current behaviors in voltage source inverters, crucial for optimizing performance and reliability in applications.

  • This module focuses on the relationship between DC link current and DC capacitor current in voltage source inverters. Students will explore:

    • Current flow dynamics in inverter systems.
    • Effects of capacitor sizing on current behavior.
    • Techniques for managing capacitor current to enhance inverter stability.

    Through theoretical and practical discussions, students will understand how DC link and capacitor currents impact inverter efficiency and performance.

  • This module provides an in-depth analysis of torque ripple in induction motor drives. Key areas of focus include:

    • Identifying sources of harmonic torque and their effects.
    • Methods to evaluate RMS torque ripple.
    • Strategies for reducing torque ripple through PWM techniques.

    Students will gain a comprehensive understanding of how to assess and mitigate torque ripple, which is essential for improving motor performance.

  • This module continues the analysis of torque ripple in induction motor drives, building on concepts introduced previously. Students will learn about:

    • Advanced techniques for evaluating harmonic torques.
    • Further strategies for reducing torque ripple in various applications.
    • Practical implications of torque ripple on drive performance.

    By the end of this module, students will have a solid foundation in understanding and managing torque ripple in induction motors, leading to enhanced operational efficiency.

  • This module focuses on the evaluation of conduction losses in three-phase inverters. Key topics covered include:

    • Understanding the factors contributing to conduction losses.
    • Methods for calculating conduction loss in inverter systems.
    • Impact of conduction loss on inverter efficiency.

    Students will learn how to assess and minimize conduction losses, which is essential for enhancing the performance and longevity of power electronic systems.

  • This module explores the evaluation of switching losses in three-phase inverters, addressing crucial aspects such as:

    • The mechanisms behind switching losses and their significance.
    • Techniques for accurately calculating switching losses.
    • Strategies for optimizing switching processes to reduce losses.

    By the end of this module, students will be equipped with the knowledge to effectively evaluate and manage switching losses in inverter applications.

  • This module focuses on the design of PWM techniques aimed at reducing switching loss in three-phase inverters. Key components include:

    • Analyzing the relationship between PWM design and switching loss.
    • Developing innovative PWM strategies to minimize loss.
    • Case studies showcasing successful implementations.

    Students will learn to devise effective PWM designs that enhance inverter efficiency while reducing operational costs.

  • This module examines the effect of dead-time on inverter output voltage, particularly for continuous PWM schemes. Key learning objectives include:

    • Understanding the necessity of dead-time in PWM control.
    • Evaluating the impact of dead-time on inverter output characteristics.
    • Strategies for compensating the effects of dead-time.

    Students will gain insights into how dead-time influences inverter performance and learn techniques to mitigate its adverse effects.

  • This module extends the discussion on the effect of dead-time on inverter output voltage, focusing on bus-clamping PWM schemes. Key topics include:

    • Comparative analysis of dead-time effects in different PWM schemes.
    • Understanding the role of bus-clamping in mitigating dead-time impacts.
    • Practical applications and implications for inverter design.

    Students will deepen their understanding of dead-time effects and learn how to optimize inverter performance through effective PWM strategies.

  • This module focuses on overmodulation in sine-triangle PWM from a space vector perspective. Key areas of exploration include:

    • Understanding the principles behind overmodulation.
    • Analyzing the effects of overmodulation on PWM performance.
    • Comparative studies of sine-triangle and space vector modulation techniques.

    Students will learn to navigate the complexities of overmodulation and its implications for inverter performance, ensuring effective control strategies.

  • This module continues the exploration of overmodulation in space vector modulated inverters. Key topics include:

    • Advanced analysis of overmodulation effects in space vector modulation.
    • Strategies for optimizing inverter performance during overmodulation.
    • Real-world applications and case studies.

    Students will deepen their understanding of overmodulation in space vector modulation and learn to implement practical solutions to enhance inverter efficiency.

  • This module addresses PWM for three-level neutral-point-clamped inverters. Topics covered include:

    • Understanding the architecture of three-level neutral-point-clamped inverters.
    • Development of PWM strategies specific to this topology.
    • Analyzing the benefits of three-level inverters in various applications.

    Students will gain insights into how the three-level configuration enhances performance and reduces losses compared to conventional inverter topologies.

  • This module continues the study of PWM for three-level neutral-point-clamped inverters, delving deeper into:

    • Complex PWM techniques tailored for three-level inverters.
    • Evaluation of performance metrics in real-world scenarios.
    • Case studies showcasing successful implementations and lessons learned.

    Students will learn to apply advanced PWM techniques to optimize performance and reliability in three-level inverter applications.

  • This module completes the study of PWM for three-level neutral-point-clamped inverters, focusing on:

    • Finalizing the development of comprehensive PWM strategies.
    • Assessing the integration of these strategies into existing systems.
    • Future trends and innovations in three-level inverter technology.

    Students will leave this module equipped with the knowledge to innovate and enhance three-level inverter applications, positioning themselves at the forefront of power electronics.