Design of a Digital Controller Based on Series Expansions of Pulse Transfer Functions

1983 ◽  
Vol 105 (3) ◽  
pp. 204-206 ◽  
Author(s):  
H. Inooka ◽  
G. Obinata ◽  
M. Takeshima
Keyword(s):  
Linear Equation ◽  
Rapid Growth ◽  
Closed Loop ◽  
Transfer Functions ◽  
Digital Controller ◽  
Control Algorithms ◽  
Series Expansions ◽  
Unknown Parameters ◽  
Single Loop ◽  
Characteristic Features

By considering the rapid growth of microcomputer technology, it is now possible to implement various control algorithms into a microcomputer and to use it as a single-loop digital controller. This paper considers a design of a digital controller which achieves an arbitrarily specified closed-loop response. A linear equation is obtained for unknown parameters of such a controller based on series expansions of relevant pulse transfer functions. Some examples are given to show the characteristic features of the method.

SINGLE-LOOP CURRENT-MODE CONTROL OF A PWM BOOST DC-TO-DC CONVERTER WITH A NON-SYMMETRIC PHASE CONTROLLER

1995 ◽  
Vol 05 (04) ◽  
pp. 699-734 ◽  
Author(s):  
MARIAN K. KAZIMIERCZUK ◽  
ROBERT S. GEISE
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
Current Mode ◽  
Loop Current ◽  
Single Loop ◽  
Mode Control ◽  
Control Scheme ◽  
Power Stage ◽  
Bode Plots ◽  
Symmetric Phase

An extensive small-signal analysis of a single-loop current-mode control strategy for a pulse-width-modulated (PWM) boost DC-to-DC power converter operating in continuous conduction mode (CCM) is proposed using a new non-symmetric phase controller. To model the boost power stage, a linear circuit model is used which includes all parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor ON-resistance, and the diode forward resistance and offset voltage. A boost power stage design example gives component design equations and will serve to illustrate the closed-loop converter design. A design procedure for the new non-symmetric phase controller is presented. Open-loop and closed-loop circuit models and transfer functions are derived for the boost PWM converter and illustrated by Bode plots. An approach is presented for simplifying closed-loop transfer functions, using Euler's identity, into a format which is conducive to modeling in any high level programming language on a personal computer. Bode plots are obtained using a data analysis software package Axum 3.0 which combines a programming language, spread-sheet, and publication quality technical graphics. The proposed control scheme directly controls the inductor current and indirectly controls the load current and output voltage. The closed-loop transfer functions of the proposed control scheme do not contain a righthalf plane (RHP) zero, in contrast to the closed-loop transfer functions of a single-loop voltage-mode control scheme. The absence of the RHP zero provides better stability by making it easier to obtain large or specified gain and phase margins.

Analog simulation of a digital three-mode controller

SIMULATION ◽  
1972 ◽  
Vol 18 (1) ◽  
pp. 35-36
Author(s):  
C.R. Clemence
Keyword(s):  
Side Effects ◽  
Digital Control ◽  
Closed Loop ◽  
Transfer Functions ◽  
Digital Systems ◽  
Digital Controller ◽  
Analog Device ◽  
Analog Simulation ◽  
Simulation Procedure ◽  
Product Specifications

Textbook designs of digital systems are often based on classical responses produced by specific closed- loop transfer functions, and offer little assistance to the "analog" engineer who is required to convert a number of analog loops to digital control while maintaining product specifications. To ensure uni form operation of the plant during the conversion, it is desirable to have as little change as possible in the response of individual loops in order to minimize unexpected side effects. This paper describes a simulation procedure which enables the engineer to incorporate the familiar analog concepts of proportional, derivative, and integral modes into the digital software and to identify the mode coefficients with corresponding software variables. Thus the digital controller can be tailored to provide mode emphasis similar to that of the analog device being replaced. The whole sys tem, including the digital software, is simulated by analog means and the gain of each mode is adjusted independently until the desired response is obtained.

scholarly journals A reinforcement learning method with closed-loop stability guarantee for systems with unknown parameters

2020 ◽  
Vol 53 (2) ◽  
pp. 8157-8162
Author(s):  
Thomas Göhrt ◽  
Fritjof Griesing-Scheiwe ◽  
Pavel Osinenko ◽  
Stefan Streif
Keyword(s):  
Reinforcement Learning ◽  
Closed Loop ◽  
Learning Method ◽  
Unknown Parameters ◽  
Loop Stability

scholarly journals Software Sensor to Enhance Online Parametric Identification for Nonlinear Closed-Loop Systems for Robotic Applications

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3653
Author(s):  
Lilia Sidhom ◽  
Ines Chihi ◽  
Ernest Nlandu Kamavuako
Keyword(s):  
Degrees Of Freedom ◽  
Closed Loop ◽  
Sliding Mode ◽  
Robot Manipulator ◽  
Parametric Identification ◽  
Recursive Least Squares ◽  
Unknown Parameters ◽  
Closed Loop Identification ◽  
Input Variables ◽  
Robotic Applications

This paper proposes an online direct closed-loop identification method based on a new dynamic sliding mode technique for robotic applications. The estimated parameters are obtained by minimizing the prediction error with respect to the vector of unknown parameters. The estimation step requires knowledge of the actual input and output of the system, as well as the successive estimate of the output derivatives. Therefore, a special robust differentiator based on higher-order sliding modes with a dynamic gain is defined. A proof of convergence is given for the robust differentiator. The dynamic parameters are estimated using the recursive least squares algorithm by the solution of a system model that is obtained from sampled positions along the closed-loop trajectory. An experimental validation is given for a 2 Degrees Of Freedom (2-DOF) robot manipulator, where direct and cross-validations are carried out. A comparative analysis is detailed to evaluate the algorithm’s effectiveness and reliability. Its performance is demonstrated by a better-quality torque prediction compared to other differentiators recently proposed in the literature. The experimental results highlight that the differentiator design strongly influences the online parametric identification and, thus, the prediction of system input variables.

Logic-Based Switching Adaptive Control of DC-DC Buck Converter

2012 ◽  
Vol 229-231 ◽  
pp. 2209-2212
Author(s):  
Bao Bin Liu ◽  
Wei Zhou
Keyword(s):  
Adaptive Control ◽  
Closed Loop ◽  
Buck Converter ◽  
Uncertain Parameters ◽  
Small Signal ◽  
Closed Loop System ◽  
Unknown Parameters ◽  
Signal Model ◽  
Small Signal Model ◽  
Control Scheme

Logic-based switching adaptive control scheme is proposed for the model of DC-DC buck converter in presence of uncertain parameters and power supply disturbance. All uncertain parameters and the disturbance are estimated together through constructing Lyapunov function. And a switching mechanism is used to ensure global asymptotic stability of the closed-loop system. The results of simulation show that even if there are multiple unknown parameters in the small-signal model, the control system of DC-DC buck converter can estimate unknown parameters quickly and accurately.

Application of Mixed H2/H∞ Data Driven Control Design to Dual Stage Hard Disk Drives

2018 ◽  
Author(s):  
Omid Bagherieh ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Control Design ◽  
Hard Disk ◽  
Data Driven ◽  
Disk Drives ◽  
Design Strategies ◽  
Data Driven Approach ◽  
Dual Stage

A data driven control design approach in the frequency domain is used to design track following feedback controllers for dual-stage hard disk drives using multiple data measurements. The advantage of the data driven approach over model based approach is that, in the former approach the controllers are directly designed from frequency responses of the plant, hence avoiding any model mismatch. The feedback controller is considered to have a Sensitivity Decoupling Structure. The data driven approach utilizes H∞ and H2 norms as the control objectives. The H∞ norm is used to shape the closed loop transfer functions and ensure closed loop stability. The H2 norm is used to constrain and/or minimize the variance of the relevant signals in time domain. The control objectives are posed as a locally convex optimization problem. Two design strategies for the dual-stage hard disk drive are presented.

scholarly journals High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery

2004 ◽  
Author(s):  
Mark Jansen ◽  
Gerald Montague ◽  
Andrew Provenza ◽  
Alan Palazzolo
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Closed Loop ◽  
Fault Tolerant ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Displacement Sensors ◽  
Rotor Support ◽  
Active Vibration ◽  
Speed Computer

Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540°C (1,000°F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.

scholarly journals Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Yu-Jun Mao ◽  
Chi-Seng Lam ◽  
Sai-Weng Sin ◽  
Man-Chung Wong ◽  
Rui Paulo Martins
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
High Accuracy ◽  
Operating Conditions ◽  
Selection Strategy ◽  
Small Signal ◽  
Pwm Converters ◽  
Modeling Methods ◽  
The Past ◽  
Conduction Mode

Among various modeling methods for DC-DC converters introduced in the past two decades, the state-space averaging (SSA) and the circuit averaging (CA) are the most general and popular exhibiting high accuracy. However, their deduction approaches are not entirely equivalent since they incorporate different averaging processes, thus yielding different small signal transfer functions even under identical operating conditions. Some research studies claimed that the improved SSA can obtain the highest accuracy among all the modeling methods, but this paper discovers and clearly verifies that this is not the case. In this paper, we first review and study these two modeling methods for various DC-DC converters operating in the discontinuous conduction mode (DCM). We also streamline the general model-deriving processes for DC-DC converters, and test and compare the accuracy of these two methods under various conditions. Finally, we provide a selection strategy for a high-accuracy modeling method for different DC-DC converters operating in DCM and verified by simulations, which revealed necessary and beneficial for designing a more accurate DCM closed-loop controller for DC-DC converters, thus achieving better stability and transient response.

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