Ki Ng

Sensitivity analysis of PI cascade control of power converter

Cascade PI control systems have been widely used in the control of two level power converters. In this control system configuration, the cascade control PI controllers are designed using synchronous-frame where in the inner-loop, two PI current controllers are used to control the d and q axis currents while in the outer-loop, a PI controller is used to regulate the voltage for load disturbance rejection. This paper proposes the model based PI controller design using the physical model parameters with specification on desired closed-loop bandwidth. Furthermore, the paper presents the the sensitivity functions in both inner and outer loops systems and discuss their association with respect to robust performance and harmonic attenuation.

PID and Predictive Control of Electrical Drives and Power Converters using Matlab®/Simulink®: Wang/PID and Predictive Control of Electrical Drives and Power Converters using Matlab®/Simulink®

PID and Predictive Control of Electric Drives and Power Supplies using MATLAB/Simulink examines the classical control system strategies, such as PID control, feed-forward control and cascade control, which are widely used in current practice. The authors share their experiences in actual design and implementation of the control systems on laboratory test-beds, taking the reader from the fundamentals through to more sophisticated design and analysis. The book contains sections on closed-loop performance analysis in both frequency domain and time domain, presented to help the designer in selection of controller parameters and validation of the control system. Continuous-time model predictive control systems are designed for the drives and power supplies, and operational constraints are imposed in the design. Discretetime model predictive control systems are designed based on the discretization of the physical models, which will appeal to readers who are more familiar with sampled-data control system. Soft sensors and observers will be discussed for low cost implementation. Resonant control of the electric drives and power supply will be discussed to deal with the problems of bias in sensors and unbalanced three phase AC currents.

FCS Predictive Control in d−q Reference Frame

In this chapter, the finite control set (FCS) predictive current control in the alpha-beta reference frame (or the stationary frame) is investigated. In the alpha-beta reference frame, the current reference signals, current feedback signals and the voltage control signals are sinusoidal signals, which differentiate the current control systems in the alpha-beta reference frame from those in the d-q reference frame. It will be shown in this chapter that the original FCS predictive controllers are single-input and single-output controllers with exceptionally simple forms. In order to track the sinusoidal current reference signals without steady-state errors, FCS predictive controller with resonant characteristic is proposed in the alpha-beta reference frame. Simulation and experimental results are used to demonstrate the efficacy of the resonant FCS predictive current controllers.

FCS Predictive Control in Reference Frame

In this chapter, the finite control set (FCS) predictive current control in the alpha-beta reference frame (or the stationary frame) is investigated. In the alpha-beta reference frame, the current reference signals, current feedback signals and the voltage control signals are sinusoidal signals, which differentiate the current control systems in the alpha-beta reference frame from those in the d-q reference frame. It will be shown in this chapter that the original FCS predictive controllers are single-input and single-output controllers with exceptionally simple forms. In order to track the sinusoidal current reference signals without steady-state errors, FCS predictive controller with resonant characteristic is proposed in the alpha-beta reference frame. Simulation and experimental results are used to demonstrate the efficacy of the resonant FCS predictive current controllers.

Resonant FCS Predictive Control of Power Converter in Stationary Reference Frame

Abstract This paper proposes resonant finite control set (FCS)-predictive control of a two level power converter. In the stationary reference frame, firstly the traditional FCS-predictive control system is shown to be closed-loop feedback proportional control system. In the presence of constraints, the objective function is a weighted error function between the desired optimal and candidate voltage control signals. The weighting coefficient in the objective function is the ratio between the sampling interval and the inductance. Secondly, it is proposed in this paper to design a discrete-time resonant controller for eliminating the sinusoidal error using a cascaded control system structure. The proposed method is simple in design and implementation with an analytical solution for the resonant controller gain. Experimental results are used to demonstrate the efficacy of the proposed approach and much improved closed-loop control performance.

Input-output linearization and PI control for a three-phase neutral point clamped boost rectifier

In this paper, PI control with input-output linearization is presented for a three-phase neural point clamped boost rectifier. The control algorithm consists of a input-output linearization inner current loop in synchronous reference frame and a PI voltage control outer-loop. There are two reference signals for this cascade controller, which are the dc link voltage reference and the q-axis current reference. They are used to regulate the dc link voltage and achieve unity power factor. A model based design method for the inner-loop and outer-loop is presented. Simulation results show the dc link control performance and the current control performance. The control performance under a distorted voltage supply condition is also shown.