Design the Loop Controller for Switching Power Supplies.

Ing. Cristoforo Baldoni

Switching power supplies loop controller design: In this article, we will explore the process of determining the output power stage transfer function H(s), also known as the Control-to-Output function, for different types of switching power supplies is the focus of this article. We’ll delve into BUCK, BOOST, BUCK-BOOST, HALF-BRIDGE, and FULL BRIDGE configurations under both voltage mode control and current mode control. Despite the intricate nature of various power supply variants that incorporate one or more output feedback mechanisms, the output power transfer function H(s) can be categorized into schematic classifications of general applicability.

We will also examine scenarios wherein it becomes necessary to consider the influence of the Right Half Plane Zero (RHPZ) and the practical implications it entails. Once the components specific to the particular power supply are appropriately dimensioned, we can reasonably approximate the transfer function that mathematically describes the output power stage. As highlighted in the article “Find Poles and Zeros of a Circuit by Inspection“, will promptly identify the POLES and ZEROS characterizing the distinct switching categories.

The subsequent step involves generating Bode plots of these functions utilizing PSpice. Based on their characteristics, we will select the most suitable compensator G(s), implementing the compensation network through operational amplifiers integrated within the microcontrollers. Employing SPICE simulation on the open loop transfer function G(s)*H(s), we can assess the system’s stability outcomes.

Lastly, we will apply this methodology to two real-world switching power supply instances: a low-power flyback converter and an off-line, half-bridge switching configuration. This approach streamlines the design process for the compensator G(s) during the prototyping phase, preceding physical measurements with instrumentation.

It’s strongly recommended to read these articles first:

By accessing this article, you can download the following SPICE simulation files related to the design of compensation for switching power supplies:

-Forward function example

-Flyback function example

-Flyback function example with a Right Half Plane ZERO

-Origin POLE compensator

-Origin POLE Transfer function implementation

-Forward function compensated example

-One ZERO two POLES compensator

-One ZERO two POLES Transfer Function Implementation

-Flyback with RHPZ compensated

-Three POLES two ZEROS compensator

-Three POLES two ZEROS Transfer Function

-Transfer function of a real Flyback converter

-Compensator for the flyback converter

-Overall compensated  transfer function of the flyback converter

-Transfer function of a real Forward converter

-Compensator for the Forward converter

-Transfer function of compensator for the Forward converter

-Overall compensated  transfer function of the Forward converter

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Microcontroller-Based PID Controller Design and Simulation.

Ing. Cristoforo Baldoni

In this article, we will explore the transition from analog PID controller design for continuous-time systems to digital controllers, including PID controller simulation. This transition involves substituting operational amplifiers, resistors, and capacitors with microcontrollers. Digital controllers offer remarkable compactness, fitting the entire controller onto a single chip, complete with A/D and D/A converters. Furthermore, digital controllers remain immune to component aging and temperature-induced value fluctuations, in contrast to analog components.

We will delve into the application of the Z-transform, which serves as the discrete-time systems counterpart to the Laplace transform. This exploration will encompass the identification of a process’s transfer function. Through a systematic, step-by-step approach, we will demonstrate the practical application of theoretical insights. This will be accomplished by analyzing a Proteus microcontroller-based project, wherein the PWM output is harnessed to regulate the temperature of an oven. The microcontroller boasts a 10-bit A/D converter.

This adaptable procedure can be easily customized with minimal adjustments for controlling various other processes.

Topics Covered:

1. Digital Control-System Block Diagrams.

2. Linear Difference Equations, Z-Transform, Inverse Z-Transform and Discrete Transfer Function.

3. Sampling and A/D Conversion: Analog to Digital Converter.

4. D/A Conversion and ZERO ORDER HOLD  (ZOH) : Relationship between the Continuous Transfer Function and Discrete Transfer Function of a Sampled Process.

5.  Manipulation of Block Diagrams for Sampled Data.

6. Methods for designing Digital Controllers and Ensuring Stability.

7. Microcontroller-Based PID Controller Design.

8. Transfer Function Identification and PID Tuning using the Ziegler–Nichols Method.

9. Practical case of a temperature control system implemented with a microcontroller PIC and simulated with ISIS Proteus: Step by step explanation of how to apply the theoretical knowledge for implementing and simulating a PID controller.

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SPICE-Based Design of PID Controllers.

In this comprehensive article, we delve into the world of industrial control systems through the lens of PID controllers using SPICE simulation. We will embark on a journey to explore the process of designing and simulating various types of PID controllers – including Proportional (P), Proportional-Integral (P.I.), Proportional-Derivative (P.D.), and Proportional-Integral-Derivative (P.I.D.) controllers, leveraging the power of SPICE simulation. The article delves into the theoretical underpinnings and practical methodologies for creating these controllers, emphasizing their importance in optimizing diverse industrial processes. Additionally, we’ll take a closer look at the subsequent implementation of these controllers, achieved using operational amplifiers. Whether you’re an engineer, a researcher, or a technology enthusiast, this article offers valuable insights into the dynamic world of PID control and its application within industrial contexts.

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Find Poles and Zeros of a Circuit by Inspection

 Ing. Cristoforo Baldoni

In this article, focused on ‘Poles and Zeros of a Circuit‘, we will explore the technique of identifying the count of poles and zeros within a transfer function, including those in complex linear networks, solely through visual inspection. This method obviates the need for calculating the analytical expression of the transfer function. By the conclusion of this article, you will have the capability to swiftly determine the number of poles upon initial examination.

Once the output is established, this approach also enables you to ascertain the quantity of zeros through inspection and subsequently compute the precise symbolic form of the transfer function. Additionally, you can calculate the exact values of both zeros and poles employing user-friendly software tools readily accessible for free. We will validate the findings using SPICE analysis.

The primary objective of this article is to delve into the concepts of poles and zeros within a transfer function, elucidating their physical significance. Furthermore, we aim to furnish valuable analytical tools to aid analog circuit designers and control systems engineers in their endeavors.

How many POLES does this circuit have?


And how many does this high-pass filter have?


If your response to the initial question is 9 or 8, or if you do not identify a fifth-order filter (with five poles) in the filter’s illustration, then you should proceed to read this article.

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Control Systems using SPICE Simulation.

Ing. Cristoforo Baldoni

Exploring the domain of Control Systems using SPICE Simulation, this article offers essential principles for designing and analyzing Feedback and Control Systems. Control Systems theory, a cornerstone of engineering and automation, involves the study of dynamic systems and their manipulation to achieve desired outcomes. These systems are omnipresent in our modern industrial technological world, seamlessly integrated into everyday devices. They play a vital role in processes as diverse as the precise positioning of a Reader’s laser, the intricate control of a hard disk head’s movement, and even the numerous biological control systems orchestrating our bodily functions.

Control Systems theory involves understanding how systems respond to various inputs and disturbances, and how to design controllers that shape these responses to achieve desired goals. These goals can include stability, accuracy, speed, and overall performance optimization. Whether it’s managing the temperature of an oven, stabilizing the flight of an aircraft, or controlling the speed of a motor, the principles of Control Systems theory provide the framework to analyze, design, and optimize these dynamic processes.

As we navigate through this article, we’ll begin by introducing the basic concepts that underpin Control Systems theory. From there, we’ll seamlessly transition into exploring how these theories come to life through the application of SPICE simulation. Our journey includes the evaluation of the Open Loop Transfer Function using the versatile tool of PSPice, providing hands-on insights into the practical implementation of control strategies. Whether you’re a novice eager to comprehend the foundations or an enthusiast seeking to refine your expertise, this article offers a holistic perspective on the symbiotic relationship between Control Systems theory and the power of SPICE Simulation.

Topics Covered:

1.  Processes, Open Loop and Closed Loop Control Systems (Feedback Systems).

2. Generic Closed Loop Schematic of Feedback Systems.

3. Physycal Processes Modeling, Differential Equations and Laplace Transform Simplification.

4. Transfer Function: Understanding Poles, Zeros and their Phisical Significance.

5. Natural and Forced Response: Residues Calculation, Simplification of identical Zeros and Poles, Dominant Poles.

6. Process Stability.

7. Steady State Erro and Systems Types.

8. Transfer Function through Bode Diagram Analysis. Examination of the Open Loop Transfer Function using SPICE Simulation.

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