Digital Controller Design Research Articles

Advanced digital control strategies for switching buck converters: A modeling perspective

Advanced digital control strategies for switching buck converters: A modeling perspective

Design and Implementation of Digital PID Control for Mass-Damper Rectilinear Systems

Design and Implementation of Digital PID Control for Mass-Damper Rectilinear Systems

Robust digital voltage mode control of buck converter with enhanced tracking performance

The digital voltage controller of power converters is used because it has many advantages over its analog counterparts. Thus, in this paper, a controller of digital voltage mode is designed and analyzed for a non-isolated DC-DC buck converter in continuous conduction mode (CCM). First, an analog controller is designed using a Bode plot to achieve the desired stability margins in the frequency domain. Next, the analog controller is discretized using bilinear transformation with the pre-warping method. The characteristics of the discretized compensator can be maintained close to the corresponding analog compensator as long as a proper sampling time is selected. The digital control scheme is simulated with a nonlinear DC-DC buck converter model in MATLAB/Simulink to investigate the controller performance. The simulation results demonstrated the validation of the proposed digital voltage-mode control design approach. The developed digital controller eliminates DC error by tracking the reference voltage, achieving a fast transient response, maintaining specified stability margins, and effectively rejecting large disturbances.

Self-Tuning Digital PIR Controller Design and Application

Self-Tuning Digital PIR Controller Design and Application

Digital Control Design Scheme for an LCL-Type Inverter Based on QPR Controller With GVWF Under Weak Grid Conditions

Digital Control Design Scheme for an LCL-Type Inverter Based on QPR Controller With GVWF Under Weak Grid Conditions

Dynamic Contraction Method approach to digital longitudinal aircraft flight controller design

Dynamic Contraction Method approach to digital longitudinal aircraft flight controller design

Design of digital controller for HEPS corrector power supply

Design of digital controller for HEPS corrector power supply

Low-order sliding mode repetitive control for uncertain linear systems perturbed by band-limited periodic disturbances

This article presents a systematic method for designing discrete-time low-order sliding mode repetitive controller for a class of uncertain linear systems. A linear system considered in this class is perturbed by band-limited periodic disturbances and parametric uncertainties. The digital controller design method we propose combines two control strategies, namely the repetitive control and the sliding mode control techniques. The proposed controller is required to be low order and is intended to reject the periodic disturbances with specific dominant frequencies and to establish robustness against plant parametric uncertainties. Moreover, the proposed method yields a repetitive controller with only a small number of delay terms and can perform fast transient responses. We show through mathematical analyses that the linear system applying the low-order sliding mode repetitive controller satisfies sliding mode stability and robustness criteria. In addition, we demonstrate via a numerical example that a servomotor controlled by the low-order sliding mode repetitive controller can track a frequency-shifted triangular signal with a short transient period and minor errors. Other examples are also presented and show that the low-order sliding mode repetitive controller exhibits better performance than other relevant control methods.

Performance Improvement by Sampling Position Approach in Dual Loop Digital ACM Controlled DC-DC Boost Converter

In DC-DC boost converter mostly discontinuous voltage ripple is associated with Equivalent Series Resistance (ESR) of the output side capacitor. This voltage ripple makes the design of digital controllers challenging in deciding the appropriate sampling position in one switching period. The necessity of Right Half Plane Zero (RHPZ) elimination, which impacts the stability is managed by shifting the sampling position to OFF-time duration. This is mostly analyzed in the frequency domain. The proposed work provides the time-domain analysis in consideration of ESR impacting the RHPZ. A dual loop Digital Average Current Mode (DACM) controller which has two sampling position freedom is considered in this brief. The ESR value of the output capacitor for extracting the benefits of RHPZ elimination is proposed with help of the discrete-time modeling technique. An analytical discussion about the influence of RHPZ elimination with time-domain characteristics such as, voltage deviation, peak-to-peak inductor current oscillations, and efficiency is presented. Finally, two 60W boost converters prototype with different output capacitor (C) and its ESR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(r_{C})$ </tex-math></inline-formula> values are developed to validate the proposed analysis.

Predictive discrete‐time sliding mode based direct power control for grid‐connected energy conversion systems

AbstractA method for digital direct power control design for grid‐connected energy conversion systems was proposed in this paper. The active and reactive powers are directly controlled with constant switching frequency by selecting an appropriate switching control sequence of voltage source converter as a key part of energy conversion systems. The control design combines a discrete‐time sliding mode control and predictive control. The selection of feasible switching control vectors is a direct result of the discrete‐time sliding mode control approach. These vectors satisfy the existence conditions of the sliding mode, but each of them induces system motion with different properties. The task of predictive control is to select an appropriate switching control sequence to reduce the chattering phenomenon, steady‐state error, and overshoot. The cost function of the prediction process is defined as the average value of both power errors on the prediction horizon of three sampling periods. Simulation results, experimental results, and results of a comparative analysis are presented in order to show the performance and effectiveness of the proposed control design.

Online Inductance Identification and FPGA-Based Real-Time Digital Control Design for APF

The harmonic suppression performance of active power filter (APF) under model predictive current control is obviously reduced, when the parameter exists a mismatch between the actual value in system and the nominal value adopted in the control. To suppress the influence of parameter mismatching, a model predictive control based on parameter identification with forgetting factor recursive least square (FFRLS) method is proposed for APF. The digital processing procedure of the FFRLS-based APF controller is detailed analyzed and designed. The identification error of inductance between identification value and the actual value is less to 6%, and the total harmonic distortion of grid current is significantly improved, especially a lower value of actual inductance. Simulation and experimental results show that the proposed method can not only effectively eliminate the influence of parameter mismatch on the control, but also result in better steady-state performance while retaining fast dynamic response.

Digital Controller Design and Implementation for AC and DC Side of 3ph qZSI

Digital Controller Design and Implementation for AC and DC Side of 3ph qZSI

Design and implementation of digital controller in delta domain for buck converter

This paper presents the design and implementation of a discrete-time controller for a DC-DC Buck converter in the complex delta domain. Whenever any continuous-time system is sampled to get a corresponding discrete-time system with a very high sampling rate, the shift operator parameterized discrete-time system fails to provide meaningful information. There is another discrete-time operator called delta operator. In the delta operator parameterized discrete-time system, the discrete-time results and continuous-time results can be obtained hand to hand, rather than in two special cases at a very high sampling rate. The superior property of the delta operator is capitalized in this paper to design the proposed controller in the discrete domain. The Proportional plus Integral (PI) controller designed in the delta domain is used to maintain the output voltage of the Buck converter at the load end for varying load and varying supply voltage conditions. The controller is designed and implemented using the DS1202 dSPACE board. The output voltage of the Buck converter is scaled to feed to the onboard analogue to digital converter of DS1202. Under the different disturbances, the error between the desired output voltage and the actual output voltage is measured and the delta PI controller is used to manipulate the duty cycle of the converter. The duty cycle of this pulse width modulation (PWM) signal is generated using a DS1202 board and is applied to the gate of the Metal Oxide Semiconductor field-effect transistor (MOSFET) via a suitable driver such that the output voltage of the Buck converter remains at its desired value.

Robust stimulated Raman shortcuts to adiabatic passage with deep learning

One of the challenging tasks in quantum control is to manipulate quantum systems with high fidelity and as fast as possible. Simulated Raman shortcuts to adiabatic passage with invariant-based optimal control is an efficient technique accurately used to transfer population between two quantum states in three-level systems. This technique requires tuning parameters continuously which results in analog quantum control. However, a digital quantum controller design is of great importance in the era of digital quantum computing. Here, we use deep reinforcement learning to obtain digital Stokes and pump fields that can realize fast and accurate population transfer between states with the same parity in the three-level Λ configuration. We find that deep reinforcement learning follows exactly theshortcuts to adiabaticity (STA) based on dynamical invariant and leads to a robust population transfer against systematic errors and dephasing. This is a promising enhancement in digital quantum information processing.

Digital Current Controller Design for SPMSM With Low Switching-to-Fundamental Frequency Ratios

High speed becomes an important development direction of permanent magnet synchronous machines (PMSM) for higher power density. However, with the reduction of the switching-to-fundamental frequency ratios (SFRs), the dynamic performance and robustness of the current controller deteriorate and even lead to instability. To address this issue, this article proposes a distinctive current controller designed directly in the discrete-time domain for PMSM, which combines two-degree-of-freedom internal model control (TDOF-IMC) with active damping. The salient feature of this controller is that from the point of directly assigning or optimizing the pole and zero coordinates, a distinctive current controller is designed. Specifically, the TDOF-IMC realizes the ability to arbitrarily arrange the pole–zero placement of the closed-loop transfer function, and, therefore, the current tracking response can be improved. The addition of active damping enhances the antidisturbance ability, and as a result, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis current oscillations effectively at low SFR are getting weakened. On this basis, current control can achieve better dynamic response and robustness at the same time. Finally, simulation and experimental results validate the effectiveness of the proposed controller.

FPGA Implementation of Fixed-Point Model for a Single-Phase AC-DC Converter with Unity Power Factor

This paper presents a design of digital control based on a fixed-point model for an application of a single phase AC-DC boost Converter with a high power factor and low current distortion. The system uses a simple closed-loop control with a slow voltage loop (outer loop) to stabilize the output DC bus voltage at the required level and a fast current loop (inner loop) to achieve input power factor correction. The digital control uses a fixed-point structure that improves the control accuracy without increasing the number of arithmetic operations and does not require specific running conditions. The behavior of the system is fully verified by using a digital simulation under Matlab/Simulink environment and experimentally with an implementation in real-time using Xilinx ISE 14.7 software, hardware description language VHDL, Xilinx FPGA ML605 board, and EVAL-AD7656 evaluation board for high-speed analog-to-digital conversion. The obtained results show a good agreement between experiments and simulations for steady-state and transient-responses.

Hexagonal Stimulation Digital Controller Design and Verification for Wireless Subretinal Implant Device.

Significant progress has been made in the field of micro/nano-retinal implant technologies. However, the high pixel range, power leakage, reliability, and lifespan of retinal implants are still questionable. Active implantable devices are safe, cost-effective, and reliable. Although a device that can meet basic safety requirements set by the Food and Drug Administration and the European Union is reliable for long-term use and provides control on current and voltage parameters, it will be expensive and cannot be commercially successful. This study proposes an economical, fully controllable, and configurable wireless communication system based on field-programmable gated arrays (FPGAs) that were designed with the ability to cope with the issues that arise in retinal implantation. This system incorporates hexagonal biphasic stimulation pulses generated by a digital controller that can be fully controlled using an external transmitter. The integration of two separate domain analog systems and a digital controller based on FPGAs is proposed in this study. The system was also implemented on a microchip and verified using in vitro results.

Single channel digital controller design for a high spinning rate rolling airframe missile

AbstractSpinning/Rolling Airframe Missiles (RAM) mostly use an analog (ON-OFF type) control approach that deflects control surfaces (fins) at minimum and maximum positions continuously, and control is achieved by applying phase shift between the minimum and maximum deflections during a complete roll cycle. Therefore, the control signal shape changes continuously during the roll cycle. In this study, a novel single channel digital controller is designed and tested for a high spinning rate (10–20 Hz) RAM. The digital controller adjusts the amplitude of fin deflections instead of applying a phase shift. In this way, control signal shapes are predetermined in design to completely decouple yaw and pitch dynamics. At the beginning of each roll cycle, the algorithm decides on the control signal shape and amplitude to apply throughout the cycle. Delays on the actuator system and sensor measurements which might lead to instability at high spinning rates are handled effectively thanks to the predetermined control signal shapes that are changing with 90-degree intervals. Detailed geometry of a surface-to-air spinning missile is used to obtain aerodynamic coefficients for the entire flight regime (i.e. from launch to terminal phase) via Missile DATCOM. The 6-DOF flight dynamics model and the controller algorithms are built in MATLAB/Simulink environment. The proposed digital controller is tested systematically for various scenarios and the performance is compared with the conventional analog control approach. The digital controller gives better performance compared to the analog approach under the influence of servo delays and sensor noise.

Project-based Learning for Control Education during COVID-19 Pandemic

The paper presents a project-based learning approach for the undergraduate level first course on control systems in the context of electrical and computer engineering program. We share the experience of a complex engineering project model that assumes no access to lab facility due to the COVID-19 pandemic but targets learning outcomes of a fundamental control system course, i.e., system modeling, performance investigation, analysis, design of analog or digital controller for a selected open-loop unstable system. The project utilizes Tinkercad Circuits which is a free online circuit simulator. The approach provides a solution to one of the challenges of remote or virtual engineering labs, i.e., a requirement of having high-performance expensive hardware and resource-intensive software support. Results are presented in terms of student samples and learning outcomes achieved at the end of the project.

Impact of the Sampling Period on the Design of Digital PID Controllers

The impact of the sampling period on the parameterization of a digital PID controller in the frequency domain is attempted using three different digital approximations of the integral action. The controller is implemented in the industrial process of regulation of the cement sulphates in the cement mill outlet. The maximum sensitivity, Ms, has been utilized as a main robustness criterion. For the same Ms, proportional and differential gain, a rise of the sampling period leads to a decrease of the integral gain ki for all the three approximations. For the same sampling period, the function between proportional and integral gain differs for the three approximations studied. If the design satisfies two criteria simultaneously, maximum sensitivity and phase margin in the current study, then the permissible PID gains zone becomes narrower.