Double Loop Control Research Articles

Research on the Composite Control Scheme for the Stabilized Loop of Inertial Stabilized Platform

A composite control scheme is proposed to solve the problems of friction toque and carrier disturbance lag in the stabilized loop of inertial stabilized platform. Based on analysis of composite control structure, the performance of single rate loop, double rate loop and composite control in the inhibition of carrier disturbance, friction torque and sensor noise are compared. In order to further verify the composite control method, an experimental setup is built. The experimental results show that: when the disturbance is 1deg-1Hz sinusoidal signal, the peak value of residual error of the single rate loop is 0.055 deg, the double rate loop is 0.031deg, and the composite control is the 0.0188deg, so the performance of isolation carrier disturbance of platform is effectively improved.

Simulation Study on Single-Phase Parallel Type of APF Double Loop Control Technique

This paper begins with analyzing the hazard of system harmonics and proposing the effectiveness of active power filter (APF) in harmonic wave inhibition. Against the background of single-phase parallel type of APF, its working principle is introduced and its mathematical model is built. Next, analyzed in details is the single-phase parallel type of APF double loop control system based on outer voltage loop and inner current loop, with the specific design procedure of PI control parameters of outer voltage loop and inner current loop presented. Finally, through MATLAB simulation, the designed system control parameters undergo verification. The simulation result indicates such single-phase parallel type of APF based on the double loop PI controller with outer voltage loop and inner current loop can ensure stability of the DC bus voltage and make effective compensation for harmonics over the mid-and low-frequency bands.

Control of temperature fields of a strapdown inertial navigation system based on fiber optic gyroscopes

Theoretical and applied issues of creating a reversible control system of time-variant temperature fields of fiber optic gyroscopes and a strapdown inertial navigation system based on such gyroscopes are considered. Mathematical models of thermal processes in the fiber optic gyroscopes and a strapdown inertial navigation system with an active double-loop reversible temperature control system based on thermoelectric coolers are constructed. Software is developed, parameters of the temperature control system are selected, computational experiments are performed, and estimates of the operation of the corresponding dynamic systems under complex thermal conditions are obtained.

Design and Simulation of a Photovoltaic Emulator System Based on a Full-Bridge Structure

In this paper, the design and simulation of a photovoltaic (PV) emulator are presented. The output characteristic and I-V curve are produced based on mathematical engineering PV module, so that they are similar to the practical curves. The proposed system consists of a single-phase full-bridge PWM rectifier and a DC/DC buck converter, which can reduce the voltage ripple and improve the power factor near the grid. The rectifier uses double-loop control strategy and the buck circuit uses the formula of the PV module to control output voltage and load current. Using Matlab simulation, the result proves feasibility and good performance of this scheme, and simulation waves can reflect the change of temperature and light intensity.

Circulating current elimination scheme for parallel operation of common dc bus inverters

In this paper, a circulating current elimination scheme for common dc bus parallel inverter system is proposed. A dead-time elimination sinusoidal pulse width modulation (SPWM) is presented to overcome the circulating current caused by dead-time effects. The circulating current elimination scheme combines dead-time elimination SPWM and double loop control method, which is compose of an outer voltage loop and an inner current loop. Synchronizing the pulse width modulation (PWM) signals of each parallel unit, the instantaneous output PWM voltages of the parallel units can be kept the same, apart from the zero crossing of load current. The proposed scheme is easy to be implemented on the digital control board using digital signal processing (DSP) and field-programmable gate array (FPGA). Experimental results are depicted to demonstrate the validity and features of the proposed circulating current elimination scheme.

Design and Implementation of a Rotary Inverted Pendulum Using Model-Based Design

Aiming at the characteristic of nonlinear and natural unsteadiness in rotary inverted pendulum system. This kind of system uses the DSP TMS320F28335 of TI as the control and testing core of this system, adopts DC motor JGB37-3530 and motor drive L298, high precision potentiometer WDY35D4 as sample controller. Angle-to-resistance-to-voltage conversion is achieved by potentiometer, sensors export analog voltage to the first-order filter for filtering noise and transmit signal to the interior of TMS320F28335 and take ADC sample, then use digital filter algorithms to filter the signal again. Finally using double-loop PID control scheme to control motor precisely. Both DSP algorithm and program are implemented by Model-Based Design in Matlab, according to the process of model-simulation-code generation, this rotary inverted pendulum realizes the function of pendulum inverted and rotated. Experiments show this system has a stable and rapid transient process, possesses good stability and resisting disturbance.

Study of Vehicle Power Supply with AC and DC Mixed Output

The paper proposes a AC and DC mixed output VPS(vehicle power supply). It is composed of a two-stage circuit with the input stage and the output stage. The input stage contains a single-phase PWM inverter, a HFT (high-frequency transformer) and an uncontrolled rectifier. The single-phase PWM inverter adopts the open-loop control strategy to convert the low DC voltage into a high-frequency one with square wave. The HFT enhances the voltage and insulates the low-voltage side from the high-voltage side. The uncontrolled rectifier transforms the square voltage into DC voltage. In the output stage, one output uses single-phase PWM inverter and the other uses a DC chopper, both of which adopt the double-loop PWM control mode. The mode consists of an outer voltage loop and an inner current loop to produce desirable voltage and power. With the two-stage control strategy, ideal output currents and the output voltages are obtained, and the input power factor is controllable. The VPS model is established on MATLAB/SIMULINK, and this system is also implemented in laboratory based on DSP TMS320F28335. The results of simulation and experiment verify the proposed VPS system.

Operation method for parallel inverter system with common dc link

The configuration of parallel inverter system (PIS) with common dc link and no isolation measure is proposed. The gate control signals for switches in parallel inverters are synchronised to achieve ideal parallel operation status. Adopting the double loop control method which is composed of an outer voltage loop and an inner current loop, PIS has good dynamic response and robustness. In addition, the circulating current caused by the delay time of control signal transmission is studied in detail. The proposed operation method is easy to be implemented on the digital control board using digital signal processing and field-programmable gate array. The simulation and experimental results are presented to demonstrate the validity and features of the proposed operation method.

Novel Design for LC-VSI Double-Loop Control System of Microsources in Microgrid Based on Typical System Setting Method

Control strategy of inverter is the foundation of microsource’s power control. Based on a typical system setting method, double-loop control system of LC filter and inverter for voltage-source inverter in microgrid is designed. The feasibility is verified via the simulation.

Design of Proportional Integral Controllers with Decouplers for Unstable Two Input Two Output Systems

A method is proposed based on the equivalent transfer function (ETF) model to design multivariable proportional integral (PI) controllers for unstable multivariable systems with delay. The simplified decoupler decomposes the unstable multiloop systems into independent loops with ETFs as the resultant decoupled process model having unstable poles. PI controllers are designed for the diagonal elements of ETFs by the synthesis method meant for unstable first order plus time delay (FOPTD) systems. Since the overshoot is higher for the unstable systems, a double-loop control structure (inner-loop diagonal proportional (P) controllers with the decoupler and outer loop only with diagonal PI controllers) is proposed to get a reduced overshoot. Two examples of two input two output (TITO) unstable systems are considered to demonstrate the simplicity and effectiveness of the proposed method.

초공동 수중운동체의 천이구간 특성을 고려한 동역학 모델링 및 심도제어 연구

A supercavitation is modern technology that can be used to reduce the frictional resistance of the underwater vehicle. In the process of reaching the supercavity condition which cavity envelops whole vehicle body, a vehicle passes through transition phase from fully-wetted to supercaviting operation. During this phase of flight, unsteady hydrodynamic forces and moments are created by partial cavity. In this paper, analytical and numerical investigations into the dynamics of supercavitating vehicle in transition phase are presented. The ventilated cavity model is used to lead rapid supercavity condition, when the cavitation number is relatively high. Immersion depth of fins and body, which is decided by the cavity profile, is calculated to determine hydrodynamical effects on the body. Additionally, the frictional drag reduction associated by the downstream flow is considered. Numerical simulation for depth tracking control is performed to verify modeling quality using PID controller. Depth command is transformed to attitude control using double loop control structure.

Reinforcement learning of ball screw feed drive controllers

Feedback controllers for ball screw feed drives may provide great accuracy in positioning, but have no close analytical solution to derive the desired controller. Reinforcement Learning (RL) is proposed to provide autonomous adaptation and learning of them. The RL paradigm allows different approaches, which are tested in this paper looking for the best suited for the ball screw drivers. Specifically, five algorithms are compared on an accurate simulation model of a commercial device, with and without a noisy disturbance on the state observation values. Benchmark results are provided by a double-loop PID controller, whose parameters have been tuned by a random search optimization. Action-critic methods with continuous action space (Policy-Gradient and CACLA) outperform the PID controller in the computational experiments, encouraging future research.

UML Model for Double-Loop Control Self-Adaptive Braking System

In this paper, we present an activity diagram model for double-loop control self-adaptive braking system. Since activity diagram helps to improve visibility of self-adaption. We can easily find where improvement is needed on double-loop control. Double-loop control is adopted since the design conditions and actual conditions can be different. The system is reconfigured in runtime by using double-loop control. We simulated to verify and validate our model by using MATLAB. We compared single-loop control model with double-loop control model. Simulation results show that double-loop control provides more consistent brake power control than single-loop control. Keywords—Activity diagram, automotive, braking system, double-loop, Self-adaptive, UML, vehicle.

Research of an Efficient LED Lighting Driver Based on Boost-Buck Converter

Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control strategy is built by adopting error amplifier and integrator control method. It is demonstrated that the new system has many advantages such as high efficiency, fast response, strong anti-interference, good stability after analyses and simulations of its working dynamic characteristics.

A Double-loop Control Structure for Tracking Control and Disturbance Attenuation

The development of high performance controllers capable of dealing with both tracking control and disturbance rejection has attracted considerable attention. This paper investigates the two-degree-of-freedom control structures with a disturbance observer and command feedforward control, respectively, and presents a double-loop control structure. The proposed control structure allows intuitive and independent tuning of disturbance rejection as well as tracking performance. Experimental results obtained from an illustrated servo control system are given to demonstrate the effectiveness and feasibility of the double-loop control structure and design methodology.

A novel double loop control model design for chemical unstable processes

In this manuscript, based on Smith predictor control scheme for unstable process in industry, an improved double loop control model is proposed for chemical unstable processes. Inner loop is to stabilize integrating the unstable process and transform the original process to first-order plus pure dead-time dynamic stable process. Outer loop is to enhance the performance of set point response. Disturbance controller is designed to enhance the performance of disturbance response. The improved control system is simple with exact physical meaning. The characteristic equation is easy to realize stabilization. Three controllers are separately design in the improved scheme. It is easy to design each controller and good control performance for the respective closed-loop transfer function separately. The robust stability of the proposed control scheme is analyzed. Finally, case studies illustrate that the improved method can give better system performance than existing design methods.

Research on PMSM Fuzzy PI Control System

In this paper, a fuzzy PI control method is proposed in order to overcoming shortcomings of traditional PI regulator control permanent magnet synchronous motor, in this paper. This method combined traditional PI control with fuzzy control is enable to achieve self-tuning fuzzy parameters PI control and take into account sensitivity, and robustness of the system. A double-loop (current loop and velocity loop) fuzzy control system is designed by this method. Modular design of the fuzzy PI controller based on FPGA chip is realized and simulation and experimental is done. The experimental results show that this system has advantages of fast response characteristic, good stability and high precision adjustment.

A Study of Novel Cuk Grid-Connected Inverter Based on Double-Loop Control

A kind of Cuk grid-connected inverter is proposed for renewable energy power generation. The grid-connected inverter using Cuk input series output parallel circuit, form a new type of non isolated single stage output parallel input series double Cuk inverter circuit. Firstly, On the basis of the topological structure and principle, the double-loop control strategy is researched to enhance its adaptability and robustness. Simulative results show that,the proposed inverter with double-loop control has better dynamic and static performances, with less output current harmonics and better waveform quality.

Autotuning algorithm of particle swarm PID parameter based on D-Tent chaotic model

An improved particle swarm algorithm based on the D-Tent chaotic model is put forward aiming at the standard particle swarm algorithm. The convergence rate of the late of proposed algorithm is improved by revising the inertia weight of global optimal particles and the introduction of D-Tent chaotic sequence. Through the test of typical function and the autotuning test of proportionalintegral-derivative (PID) parameter, finally a simulation is made to the servo control system of a permanent magnet synchronous motor (PMSM) under double-loop control of rotating speed and current by utilizing the chaotic particle swarm algorithm. Studies show that the proposed algorithm can reduce the iterative times and improve the convergence rate under the condition that the global optimal solution can be got.

A Study on a Class of Double-Loop Networked Control System with Differential Sampling Rate and State Feedback

For a class of double-loop networked control system with differential sampling periods is studied in this paper. Its mathematical model is set up based on time-delay theory, and its stability conditions are obtained based on Lyapunov-Krasovskii functional and free-weighting matrices approach. On this basis, the design method of the controller to stabilize this networked control system with state feedback is explained. Finally, an example of the inverted pendulum is presented to test the validity and effectiveness of the methods proposed in this paper.