Abstract

     This seminar covers the basics of feedback loop design for operational amplifiers and PWM converters operating in voltage or current mode including analog and digital feedback. It discusses, in an intuitive way, the basic theory and design methods that can be used to close the loop in amplifiers and switch mode systems. The approach to be discussed does not require any elaborate mathematical analysis, yet it is accurate to the level required in practical systems. The proposed design techniques to be discussed in the seminar are based on simulation models that will be covered and demonstrated by many examples.  The seminar addresses the design of analog feedback (for amplifiers and PWM systems) as well as digital control (for PWM systems). The advantages and limitation of each approach will be delineated in relation to present day technology. The issues to be discussed will be supported by design examples and the resulting responses will be demonstrated by simulation.

The seminar is of intermediate level intended for novices and experienced engineers in the area of analog and power electronics.

Seminar Outline

1. Basics of feedback theory and graphical representation

·       Block diagram

·       Behavior at large and small LoopGains

·       The use-friendly  graphical representation of the LoopGain

2. Stability criteria
   • Nyquist
   • Bode plain
   • The  Aol, 1/B plots
3. Relationship between LoopGain and dynamic response

·       Overshoot and Q

·       Output impedance

4. Operational Amplifiers bandwidth and stability issues
   • Voltage Feedback Amplifiers (VFA)
   • Current Feedback Amplifiers (CFA)
5. Compensation by internal circuitry
6. Compensation by external circuitry
7. PWM converters as feedback systems

·       Block diagram

·       What is Aol, what is Beta

·       Response in closed loop

8. Voltage Mode

·       Block diagram

·       Modulator

·       Demo circuit and response

·       Characteristics of open loop

9. Average Current Mode (ACM) control

·       Block diagram

·       Modulator

·       Demo circuit and simulated response

·       Characteristics of open loop

10. Peak Current Mode (PCM) control

·       Modulator

·       Demo circuit and response

·       Characteristics of open loop

11. Simulation tools

·       Cycle by cycle sinusoidal perturbation injection

·       PSPICE and PSIM plus demo

·       The switched inductor model

·       Small signal (AC) analysis

·       The duty cycle generator

·       Demos of average model and response (Voltage mode, average current peak current mode)

12. Analog feedback networks in PWM converters

·       Shaping Beta

·       The lag-lead network

·       The double zero network

13. Digital feedback in PWM converters

·       Block diagram

·       Discrete control

·       S to z transformation

·       The delay issue

·       A/D and Modulator resolutions

·       Design example

·       Comparing analog to digital control

14. Q&A

Control Design of PWM Converters: The User Friendly Approach

Computer Aided Analysis and Design

of Single Phase APFC Stages

Feedback Design in Operational Amplifiers and  PWM Converters:

The User Friendly Approach

Fundamentals of PWM Converters

Introduction to CMOS Operational Amplifiers

Control Design of PWM Converters:

 The Intuitive Approach

Fundumentals of PWM Converters

Computer Aided design of Power Factor Correction Systems

Power Electronics of Piezoelectric Elements

Introduction to Power Management for Portables

Dynamics and Stability of Switch Mode Converters

Modern Soft Switched Converter Topologies

Control Design of PWM Converters: The User Friendly Approach

Switched Capacitors Converters

Essentials of Switch Mode Converters

מגברי שרת מודרניים

Power Electronics of Piezoelectric Elements

Digital Control Design of PWM Converters: The Time-Domain Approach