Closed-loop Proportional-integral Control Research Articles

Voltage drift compensation in charge amplifiers for DC measurements: Application to piezoelectric paint sensors

Voltage drift over time in charge amplifiers is a problem not fully solved yet for DC measurements and continues to be a challenge for the scientific community. In this study we analyse the factors that cause this unwanted effect and propose a new method to compensate it. An automatic electronic circuit compensates the drift effect in two stages: first, a closed-loop proportional–integral control is used to bring the output voltage of the charge amplifier to zero and hold it while no measurement is being taken; and second, the voltage drift is compensated with an open-loop control when measurement is being taken. The proposed method allows us to compensate the voltage drift whatever its magnitude. Simulation and experimental results show that the drift effect in the output voltage of the charge amplifier is attenuated up to 99%.

Small-signal Model for Dual-active-bridge Converter Considering Total Elimination of Reactive Current

Emerging technologies such as electric vehicles, sol-id-state transformers, and DC transformers are implemented using the closed-loop bi-directional dual-active-bridge (DAB) converter. In this context, it is necessary to have average models that provide an efficient way of tuning the proportional integral (PI) compensator parameters for large- and small-signal applications. We present a novel small-signal model (SSM) for DAB converter with a single closed-loop PI controller and the total elimination of reactive current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</sub> =0). The method applies a modulation technique for I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</sub> =0 and introduces a composite function in the controller while reducing the original nonlinear switching model, which allows to decrease the order of the transfer function and analyze the closed-loop operation. The proposed SSM is analyzed using different response time, load, and DC voltage changes. The simulation and experimental results demonstrate the ease of implementation and effectiveness of the proposed model with respect to other SSM techniques.

Design of Inverter Side of Modular Grid Simulator Based on Proportional integral-Quasi-proportional resonance Control

The tracking of a given voltage in the traditional double closed-loop proportional integral control in the current power grid simulator has problems such as static difference, delay and oscillation. It is proposed that the voltage outer loop and current inner loop of the inverter side of the power grid simulator adopt proportional integral and quasi-proportional resonance control respectively, and the topology of the inverter adopts a cascaded modular design to establish a single-phase inverter model. Compared with the traditional double closed-loop proportional-integral control, it is verified that the proportional-integral-quasi-proportional resonant controller can effectively improve the system’s ability to track the command voltage and the stability of the output voltage.

Closed-Loop PI Control of an Organic Rankine Cycle for Engine Exhaust Heat Recovery

The internal combustion engine (ICE) as a main power source for transportation needs to improve its efficiency and reduce emissions. The Organic Rankine Cycle (ORC) is a promising technique for exhaust heat recovery. However, vehicle engines normally operate under transient conditions with both the engine speed and torque varying in a large range, which creates obstacles to the application of ORC in vehicles. It is important to investigate the dynamic performance of an ORC when matching with an ICE. In this study, the dynamic performance of an ICE-ORC combined system is investigated based on a heavy-duty diesel engine and a 5 kW ORC with a single-screw expander. First, dynamic simulation models of the ICE and the ORC are built in the software GT-Power. Then, the working parameters of the ORC system are optimized over the entire operation scope of the ICE. A closed-loop proportional-integral (PI) control together with a feedforward control is designed to regulate the operation of the ORC during the transient driving conditions. The response time and overshoot of the PI control are estimated and compared with that of the feedforward control alone. The results based on the World Harmonized Transient Cycle (WHTC) indicate that the designed closed-loop PI control has a shorter response time and a better trace capacity during the dynamic processes. The average output power and thermal efficiency during the WHTC cycle are improved by 3.23% and 2.77%, respectively. Compared with the feedforward control alone, the designed PI control is more suitable for practical applications.

Design and analysis of controllers for high voltage gain DC-DC converter for PV panel

Bidirectional high gain DC-DC buck boost converter is a virtual interface among PV source and inverter fed motor drive. In this article, a PV panel integrating a non-isolated bidirectional DC/DC converter that has high voltage gain voltage and a 3 phase three level DC/AC inverter is projected. It highlights the comparison between proportional integral controller (PIC), fractional order proportional integral derivative Controller (FOPIDC) and fuzzy logic controller (FLC) based Bidirectional DC/DC Power Converter System (BDDPCS). The design, model and simulation using SIMULINK of open loop BDDPCS and closed loop PIC, FOPIDC and FLC based BDDPCS are done and the results are discussed. The findings indicate higher performance for FLC based control of BDDPCS. The proposed BDDPCS has merits such as bidirectional power transferability, lesser hardware count with enhanced dynamic response. The hardware of BDDPCS is tested and the experiment result is compared in association with simulation results.

An Improved Control Method Based on Source Current Sampled for Shunt Active Power Filters

Active power filters (APFs) are dynamic power electronic devices that suppress harmonics and reactive power. To simplify the detection and extraction of traditional APF harmonics and reactive current, this paper proposes a direct source current control based on a three-phase three-wire shunt APF. The compensation principle and control method of the source current are analyzed systematically. The currents can be controlled without static errors by a proportional-integral (PI) controller in d-q rotating coordinates. Therefore, the compensation accuracy and dynamic performance of the system can be improved by the control strategy. Moreover, considering the grid voltage fluctuations, a droop regulator is proposed to address the impact of DC-link voltages on APF power losses and compensation performance. The regulator is combined with a traditional voltage outer loop PI control to achieve a comprehensive optimization between the power loss and compensation performance of the APF system. Finally, the inner current loop and the outer voltage loop form a double closed-loop cascade PI control structure to achieve the control effect of the APF. Simulation and experimental results verified the validity and feasibility of the APF control approach.

Hybrid BBO-PSO-based extreme learning machine neural network model for mitigation of harmonic distortions in micro grids

Microgrid tends to be the cluster of some of the renewable energy sources. The most important research area in the power distribution system side is the improvement in the quality of power delivered to the end users. This paper focuses on enhancing the power quality of the microgrid system; shunt active power filters (SAPF) is employed at the distribution side and to design an appropriate controller that achieves a better compensation for the considered SAPF. It is to be noted that the compensation methodology is dependent on the regulation process of the DC-link voltage. Traditionally, this regulation process is carried out employing a closed loop proportional-integral controller. In this paper, a hybrid biogeography-based optimisation – particle swarm optimization-based extreme learning machine neural network model is proposed to design the compensation for the SAPF and to mitigate the harmonics so that effective power gets delivered through the grid.

Dynamic performance enhancement for nonlinear stochastic systems using RBF driven nonlinear compensation with extended Kalman filter

In this paper, a novel hybrid control method is proposed to enhance the tracking performance of the Proportional–Integral (PI) based control system for a class of nonlinear and non-Gaussian stochastic dynamic processes with unmeasurable states. The system performance is presented by tracking error entropy as the system is nonlinear and subjected to non-Gaussian noises. The well-known kernel density estimation (KDE) technique is employed to estimate the entropy because the precise statistical property of noises is not available for many industrial processes. Since in many industrial cases gains of PI controllers are fixed, a compensative controller is designed without changing the existing closed loop PI controller. Moreover, the compensative signal is formed using the estimated states from the extended Kalman filter (EKF) and a nonlinear compensation realized by the radial basis function (RBF) neural network. The weights of RBF are trained to minimize the entropy of the closed loop tracking error. The convergence of RBF network is discussed and the stability of the resulting closed-loop control system is analysed in mean square sense. Finally, two numerical examples and a practical system simulation are given to illustrate the effectiveness of the proposed control method.

A Power Module Designed for Compressed Plasma in EAST

Magnetic compression (MC) technology was recommended for tokamak to study compressed plasma and a power module have been designed here for developing its server power supplier. The minor-radius compression is one of the most effective methods to improve the performance parameters of existing tokamaks, enabling the fusion plasmas operated at high density, high temperature, and high beta. In this paper, a high-frequency and high-power supply system is proposed, used for powering coils of MC within the vacuum chamber of the experimental advanced superconducting tokamak. The basic of the power module is an ac/pulse converter, implemented by a series-resonant full-bridge circuit and controlled by pulsewidth modulated. Also, control method adopts current closed-loop proportional–integral control, which has less than 3-ms current response time in real time. The converter is analyzed and the design procedure is discussed. Experimental results obtained from a 3-kW converter prototype are presented to validate the converter’s performance with the redesigned control board.

Reactive Power Compensation Using Induction Motor Driven by Nine Switch AC-DC-AC Converter

Induction motors (IM) used for various industrial applications operate with lagging power factor. Electrical distribution agency insists high power factor operation and it gives incentives on operating a system closer to unity. This paper presents a novel reactive power compensation using IM driven by nine switch ac–dc–ac converter for a high power factor operation at the point of common coupling (PCC). The nine switch converter (NSC) with leading power factor operation delivers reactive power to the PCC. Thus, reactive power required for another load at PCC is compensated. Modified sinusoidal pulse width modulation is developed for NSC to operate the active front end rectifier and an inverter simultaneously to feed three-phase IM. A closed loop proportional integral control technique is developed to achieve desired VAR compensation. As per the required VAR compensation, front end rectifier voltage is modified. This is achieved by phase shifting of front end rectifier modulation reference by an angle $\delta$ with respect to utility phase voltage. The PCC phase voltage is continuously sensed to track instantaneous phase angle $\theta$ using synchronous reference frame phase lock loop. The analysis of VAR compensator is presented in the d-q reference frame. The proposed system is simulated in MATLAB for VAR compensation at PCC with 5.4 hp induction motor drive to test the performance of VAR control loop. To validate the feasibility of the proposed system an experimental prototype is developed with 1 hp induction motor drive. Gate pulses are generated using digital signal controller dsPIC33EP256MU810. The simulation and experimental results proved the feasibility of the proposed VAR compensation system.

Suppressing epileptic activity in a neural mass model using a closed-loop proportional-integral controller.

Closed-loop control is a promising deep brain stimulation (DBS) strategy that could be used to suppress high-amplitude epileptic activity. However, there are currently no analytical approaches to determine the stimulation parameters for effective and safe treatment protocols. Proportional-integral (PI) control is the most extensively used closed-loop control scheme in the field of control engineering because of its simple implementation and perfect performance. In this study, we took Jansen’s neural mass model (NMM) as a test bed to develop a PI-type closed-loop controller for suppressing epileptic activity. A graphical stability analysis method was employed to determine the stabilizing region of the PI controller in the control parameter space, which provided a theoretical guideline for the choice of the PI control parameters. Furthermore, we established the relationship between the parameters of the PI controller and the parameters of the NMM in the form of a stabilizing region, which provided insights into the mechanisms that may suppress epileptic activity in the NMM. The simulation results demonstrated the validity and effectiveness of the proposed closed-loop PI control scheme.

Double Closed-Loop PI Control of Three-Phase Inverters by Binary-Coded Extremal Optimization

How to design an effective and efficient double closed-loop proportional–integral (PI) controller for a three-phase inverter to obtain satisfied quality of output voltage waveform is of great practical significance. This paper presents a novel double closed-loop PI controller design method for a three-phase inverter based on a binary-coded extremal optimization (BCEO) algorithm. The basic idea behind the proposed method is first formulating the optimal design problem of double closed-loop PI controller for a three-phase inverter as a typical constrained optimization problem, where the total harmonic distortion and the integral of time weighted absolute error of output voltage waveform are weighted as the optimization objective function, and then a BCEO algorithm is designed to solve this formulated problem. The superiority of the proposed method to Z-N empirical method, binary-coded genetic algorithm, binary-coded particle swarm optimization is demonstrated by both simulation and experimental results on a 20-kW three-phase inverter with nominal and variable loads.

Control strategy and hardware implementation for DC–DC boost power circuit based on proportional–integral compensator for high voltage application

For high-voltage (HV) applications, the designers mostly prefer the classical DC–DC boost converter. However, it lacks due to the limitation of the output voltage by the gain transfer ratio, decreased efficiency and its requirement of two sensors for feedback signals, which creates complex control scheme with increased overall cost. Furthermore, the output voltage and efficiency are reduced due to the self-parasitic behavior of power circuit components. To overcome these drawbacks, this manuscript provides, the theoretical development and hardware implementation of DC–DC step-up (boost) power converter circuit for obtaining extra output-voltage high-performance. The proposed circuit substantially improves the high output-voltage by voltage-lift technology with a closed loop proportional–integral controller. This complete numerical model of the converter circuit including closed loop P-I controller is developed in simulation (Matlab/Simulink) software and the hardware prototype model is implemented with digital signal processor (DSP) TMS320F2812. A detailed performance analysis was carried out under both line and load regulation conditions. Numerical simulation and its verification results provided in this paper, prove the good agreement of the circuit with theoretical background.

Half Load-Cycle Worked Dual Input Single Output DC/AC Inverter

A novel half load-cycle worked dual input single output (DISO) DC/AC inverter is presented. The basic circuit consists of a dual buck regulator, which works in continuous current mode. The working principle of DISO DC/AC inverter has been used. The control method applied for half load-cycle worked DISO DC/AC inverter has been studied. The control effects of the open-loop proportional control and closed-loop proportional-integral control are compared by using PSIM software. The parameters are adopted in the realistic simulation and experiment test. Moreover, the waveforms, such as voltage of modulation reference signal and output voltage, were given. The simulation and experiment results proved that the half load-cycle worked DISO DC/AC inverter could achieve good performance, gain a line frequency of 50 Hz, and verify the correctness of theoretical analysis.

Precise position control of shape memory alloy actuator using inverse hysteresis model and model reference adaptive control system

Position control of Shape Memory Alloy (SMA) actuators has been a challenging topic during the last years due to their nonlinearities in the governing physical equations as well as their hysteresis behaviors. Using the inverse of phenomenological hysteresis model in order to compensate the input–output hysteresis behavior of these actuators shows the effectiveness of this approach. In this paper, in order to control the tip deflection of a large deformation flexible beam actuated by an SMA actuator wire, a feedforward–feedback controller is proposed. The feedforward part of the proposed control system, maps the beam deflection into SMA temperature, is based on the inverse of the generalized Prandtl–Ishlinskii model. An adaptive model reference temperature control system is cascaded to the inverse hysteresis model in order to estimate the SMA electrical current for tracking the reference signal. In addition, a closed-loop proportional–integral controller with position feedback is added to the feedforward controller to increase the accuracy as well as eliminate the steady state error in position control process. Experimental results indicate that the proposed controller has great accuracy in tracking some square wave signals. It is also experimentally shown that the suggested controller has precise tracking performance in presence of environmental disturbances.

DC/AC Converter Based on Buck Regulator

The introduction of DC/AC converter based on buck regulator is firstly shown, and the analysis of the converters working principle is taken. The control method applied for DC/AC converter based on buck regulator is studied also. The control effect of the open-loop proportional-differential control and closed-loop proportional-integral control are compared by using PSIM software. The parameters adopted in the realistic simulation, waveforms such as voltage of modulation reference and load were given. The simulation results proved that adopting the DC/AC converter could achieve a good performance and can gain a line frequency as 50Hz and the correctness of theoretical analysis.