Double Loop PI Control Research Articles

Analysis and Simulation of Three-Input DC-DC Converter with Bipolar Symmetric Outputs

This paper presents a three-input high-gain DC-DC converter with bipolar symmetric outputs. The advantages of a bipolar DC grid are higher reliability, flexibility, and efficiency as compared with the unipolar DC grid. Therefore, the proposed converter is designed to connect directly with the bipolar DC grid due to its bipolar symmetric outputs. The three input voltage sources to the converter are operated in a sequential manner from the first voltage source to the last one, with each source providing power at a level proportional to its duty cycle. Similarly, when the sources are equal, they operate in a sequential manner with their specific power. In addition, the proposed converter is designed to provide the required power to the grid under both simultaneous or individual from three input voltage sources. A double-loop PI controller is applied to regulate the converter output voltages and the control loop is analyzed and the transfer function relating reference voltage to output voltage is derived. Voltage balance control is provided to ensure that the outputs remain symmetrical despite changes in load conditions or input voltage. A converter with a power rating of 1000W and output voltage levels of 200V, -200V, and 400V is designed. The three supply voltage of 150V,100V, and 75V are used. The converter is tested under a variation of supply voltages and load using MATLAB/SIMULINK. The results show the feasibility and effectiveness of the proposed converter.

Performance evaluation of a PMDC motor with battery storage control and MPPT based solar photovoltaic system

This paper analyzes and demonstrates the performance of a solar photovoltaic (SPV)-fed permanent magnet DC (PMDC) motor under various operating conditions. In this configuration, a 5HP PMDC is coupled to a SPV system and a boost converter has been interfaced between them to regulate the DC output voltage acquired from the SPV system. The switching pulse to the converter has been provided by the maximum power point tracking (MPPT) controller (P&O and INC) in order to acquire maximum and desired power across the DC link with varying irradiance. A battery energy storage system (BESS) is often used in association with this configuration caused by the non-linear nature of the SPV system and to overcome the volatility of the DC connection affected by environmental effects. For this purpose, a double loop PI controller is analyzed, and examined the DC link. Additionally, the operation of bidirectional DC-DC converter in buck and boost mode during battery charging and discharging is also performed. This operation ensures maintaining a constant and continuous power across the DC link to regulate the PMDC motor consistently. A comparison of results has also been presented for both incremental and conductance (INC) and P&O controllers. The mathematical modeling of configuration has been performed in MATLAB/Simulink software. The results and key findings have been tabulated and even elaborated graphically.

SIMULATION OF CLOSED LOOP VOLTAGE CONTROL OF SEPIC CONVERTER

In this study, a robust output SEPIC DC-DC converter is designed and simulated. The studied single ended primary inductor converter (SEPIC) output voltage is regulated to a constant value regardless of its input. A double loop PI controller is designed and tuned for the voltage and current control which yields a control technique that results in simple implementation by reducing complexity. The multiloop control technique is used to improve converter behavior in case of wide system parameter variations. The controller parameters and design procedure are provided for the SEPIC converter for non zero current operation mode. The proposed implementation of the controlled SEPIC converter has been simulated in Matlab/Simulink environment. The simulations have been done with various operating conditions. Results show that the PI-controlled SEPIC rejects the disturbances and provides good tracking performance

Uçaklarda Kullanım Amaçlı Interleaved Süper Lift Luo Dönüştürücü Tasarımı

The main purpose of this study is to adapt a 28V battery powered super Lift Luo converter topology to the aircraft systems by adding the interleaving feature. It is aimed to have better efficiency compared to conventional designs. F-22 military aircraft and civil aircraft such as Boeing 787 use 270V DC for battery systems. New standards for the avionics using 270V DC may not apply to older avionics. Therefore, conversion from 28V to 270V can be an advantageous application for both new and old systems. As a result, an interleaved super lift Luo converter has been designed to increase the voltage from 28V to 270V with a quite high conversion ratio so existing old systems stay up-to-date due to developments. Analysis of this new interleaved super lift Luo converter was carried out with a double loop PI controller. The topology uses silicon carbide MOSFETs as high-frequency switches. This paper shows the design philosophy of the converter and proves the system with simulations.

1.2kW Interleaved synchronous buck converter design for aviation systems

The principal aim of this work is to design a battery-operated 1.2kW interleaved synchronous buck converter for aviation systems to obtain lower losses compared to the existing topologies. It is desired to achieve at least a 5% loss reduction. Military aircrafts such as F-22 and civil aircraft as Boeing 787 are using the 270V DC for their battery systems. Although 270V DC system has some advantages such as reducing loses and the passive element sizes, old avionics that have been designed, produced and used since the second world war may not be compatible with the 270V DC system. Conversion from 270V to 28V appears to be quite promising for both old and new systems. Therefore, a buck converter design for 270 to 28V conversion is proposed in this study to adapt older avionics technology to accommodate new achievements. The analysis of the SiC MOSFET based interleaved synchronous buck converter with a double loop PI controller is presented. The paper demonstrates the principles of the design and discusses possible future developments. The concept is verified using simulations.

Fuel cell and ultracapacitor energy system control using linear quadratic regulator proportional integral controller

Application of fuel cell (FC) in power generation requires efficient power converters and controllers for hybridization of energy storage devices. This paper presents the control technique in a fuel cell and ultracapacitor hybrid system to eliminate the slow dynamic problem of FC. The control technique involves a linear quadratic regulator and proportional integral (LQR–PI) controller, where the FC boost converter and the UC bidirectional converter are controlled using a double-loop PI controller and a voltage-mode LQR controller, respectively. The simulation with different types of load was performed to compare the performance of the proposed controller with both PI and LQR controllers. The results revealed that the LQR–PI controller had better overshoot and undershoot responses (7.37% and 6.43%, respectively) than the proportional integral controller (11.47% and 11.42%, respectively) and linear quadratic regulator (23.87% and 21.5%, respectively). The energy sharing performance was verified through variation in load resistance and disturbances in bus voltage. The voltage recovery time of LQR–PI controller was slightly higher (200 ms) than that of the LQR controller (23.8 ms) and, however, lower than that of the PI controller (300 ms). The results revealed that the proposed controller is efficient for load voltage as well as load current fluctuations.

SRF Based Output Voltage Control of 3-Level 3-Phase 4-Leg AT-NPC Inverter

This paper proposes a synchronous reference frame (SRF) based high performance output voltage controller for the 3-level 3-phase 4-leg (3P4L) advanced T-type neutral point clamped (AT-NPC) inverter operated in stand-alone mode. 3-phase inverters for stand-alone operation are required to provide 3-phase balanced nominal voltage under different load types such as unbalanced linear and non-linear loads. 3P4L inverters working with these types of load allow controlling zero sequence voltage by additional fourth leg. The main contribution of this work is the control of the 3-level 3P4L AT-NPC inverter with an LC-type filter modeled based on the output voltage and capacitor current feedback in the synchronous coordinate system. According to obtained capacitor current decoupled model, double loop PI controller is adopted to control the output voltage of the inverter. An inner capacitor current feedback loop is employed to provide fast dynamic response and active damping of the capacitor current. Finally, transient and steady state operation performance of the controller have been tested with PSIM simulation studies considering different load types. Simulation results validate that the proposed SRF based double loop PI controller ensure high dynamic response and high quality output voltage with less than 3% total harmonic distortion (THD) value for the 3-level 3P4L AT-NPC inverter.

Control of an <italic>LLC</italic> Resonant Converter Using Load Feedback Linearization

LLC resonant converter is a nonlinear system, limiting the use of typical linear control methods. This paper proposed a new nonlinear control strategy, using load feedback linearization for an LLC resonant converter. Compared with the conventional PI controllers, the proposed feedback linearized control strategy can achieve better performance with elimination of the nonlinear characteristics. The LLC resonant converter's dynamic model is built based on fundamental harmonic approximation using extended describing function. By assuming the dynamics of resonant network is much faster than the output voltage and controller, the LLC resonant converter's model is simplified from seven-order state equations to two-order ones. Then, the feedback linearized control strategy is presented. A double loop PI controller is designed to regulate the modulation voltage. The switching frequency can be calculated as a function of the load, input voltage, and modulation voltage. Finally, a 200 W laboratory prototype is built to verify the proposed control scheme. The settling time of the LLC resonant converter is reduced from 38.8 to 20.4 ms under the positive load step using the proposed controller. Experimental results prove the superiority of the proposed feedback linearized controller over the conventional PI controller.

Double-loop PI controller design of the DC-DC boost converter with a proposed approach for calculation of the controller parameters

Parameters of digital proportional–integral/proportional–integral–derivative controllers are usually calculated using commonly known conventional methods or solution of discrete-time equations. In literature, a model-based compact form formulation for calculation of discrete-time proportional–integral/proportional–integral–derivative controller parameters has not been come across yet. The proposed model-based compact form formulations are introduced to calculate the proportional–integral parameters in discrete time as a new approach. Generally, different types of control techniques are chosen in similar studies for double-loop control for direct current–direct current boost converter control except proportional–integral/proportional–integral. In this study, double-loop proportional–integral controller is used as a different control method from literature. By this way, the most important advantages of the proposed study are to reduce different design methods to a unique proportional–integral design method and shorten all calculations. The accuracy of the double-loop proportional–integral controller’s parameters calculated using the model-based compact form formulations is validated both in simulation and experimental studies under various disturbance effects. Satisfactory performance of the proposed controller under model uncertainty and other cases are comparatively shown with the predefined performance criteria.

Active Disturbance Rejection Control for a Flywheel Energy Storage System

This paper presents the application of the Active Disturbance Rejection Control Technique (ADRCT) to improve the performance of a Flywheel Energy Storage System (FESS). The FESS is designed for the DC MicroGrid (MG) application. It mainly consists of a flywheel with a coaxial BrushLess DC (BLDC) machine, a three-phase full-bridge circuit, and a bidirectional Buck–Boost converter. A model-independent controller based on the ADRCT, which can estimate and compensate model uncertainties and unknown disturbances in real time, is designed for the bidirectional Buck–Boost converter control in the FESS. Simulations and experiments are conducted in both charge and discharge mode to verify the performance of the proposed controller by comparison with a traditional double loop PI controller. Results show that the new controller is more robust and more adaptive. It has a better anti-disturbance capability and a higher dynamic performance than the PI controller. Moreover, to adapt to different applications and operating conditions, the charging process of the FESS is further improved. Strategies on maximum torque control and power limiting control are developed and realized on the experimental platform.

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.

Modeling and Simulation of Elevator as Energy Saving System Based on Isolation Bidirectional DC/DC Converter

To solve the problem as influence of feedback elevator energy saving device on power quality and high cost of ultracapacitor storage elevator energy saving device, isolation bidirectional DC/DC converter is used. By analysis and modeling of isolation bidirectional DC/DC converter with small signal analysis method, double loop PI control strategy is introduced. The technical difficulty that high transformation ratio transform of DC bus voltage to ultracapacitor voltage is overcome. Cost of elevator energy saving device is reduced at the same time when storage and reuse of elevator feedback energy are realized. Based on the advantage of high current discharge, high current provided by ultracapacitor reduces impact on power grid when elevator starts. The effectiveness and feasibility of the control method is proved through MATLAB/Simulink simulation.

Robust DC/DC buck converter using conditional integrator compensator

An internal model control using a conditional integrator compensator is proposed for the robust output regulation of a DC/DC buck converter. Based on the input-output linearisation from the state-space averaged model of the DC/DC buck converter, the robust output regulation problem of this type of converter can be converted into a robust stabilisation problem of an augmented system consisting of the given buck converter and the internal model by introducing a proper internal model. Another advantage of the proposed method is to sense the capacitor current instead of the inductor current. The effectiveness of the proposed converter is verified by comparing the proposed controller performance with single-loop PI control and double-loop PI control under load disturbances and supply voltage variations.