Ya-Xiong Wang

Robust Time-Delay Control for the DC–DC Boost Converter

This paper studies a robust control for regulating a boost converter capacitor output voltage. The boost converter is inherently a highly nonlinear system that displays interconnected state variables and system parameter variations due to load change with input disturbances. Therefore, a robust control scheme is required to cope with these characteristics. The main objective of controlling the capacitor output voltage is to keep the output voltage constant under input voltage variations with fast response, and little overshoot and ripples. To satisfy this objective, a robust control with time-delay concept is introduced. The control utilizes time-delayed switching input to the converter, as well as output current and voltage variables, to replace the unknown dynamics and disturbance. To prove the effectiveness of the algorithm, two operating point variations are considered: variations in source voltage, and changes in output load. Simulations are performed using MATLAB/Simulink to show the effectiveness of the algorithm by choosing the output voltage lift, drop, settling time, and ripples as the system performance criteria. Then, a comparison of the results is made of the proportional and integral control, and the sliding mode control. An experimental test is also performed to demonstrate the effectiveness of the system.

Real-Time Control for Air Excess Ratio of a PEM Fuel Cell System

This paper studies the modeling and air flow control for a proton exchange membrane (PEM) fuel cells using model predictive control (MPC). The PEM fuel cell model was constructed using cell current-voltage relationships, including Nernst voltage, activation, ohmic, and concentration voltage loss. A thermal model was also included for PEM fuel cell model to represent the pressure characteristics. The validity of the model was evaluated by determining the model parameters, and its accuracy was verified against the experimental data. To prevent starvation that might occur in the fuel cell hybrid vehicle system, air flow control was utilized using MPC. MATLAB/Simulink model was first constructed to simulate the efficacy of MPC using the linearized model. The validity and performance superiority of the model were then confirmed by comparing them with the proportional-integral control result. To apply the MPC in real-time, a LabVIEW-based experimental rig was constructed, and its efficacy in preventing air starvation was verified.

Bidirectional DC-DC converter design and implementation for lithium-ion battery application

Bidirectional DC-DC converter is potentially used for an energy charging or discharging device; however, the converter displays highly non-linear characteristics since its internal system parameter varies depending on the operation mode and the disturbance engagement. To cope with the non-linearity, a bidirectional DC-DC converter based on time delay control (TDC) is designed and validated for lithium-ion battery application. Control-oriented lithium-ion battery-fed bidirectional DC-DC converter model is constructed with MATLAB/Simulink. Converter PWM duty ratio control technique based on TDC is subsequently designed and assembled for lithium-ion battery operation regulation. Moreover, to validate the efficacy of the present approach, proportional-integral (PI) control is implemented and its results are compared with TDC results. The experimental implementation is performed with National Instrument (NI) Lab VIEW, whose results show excellent bidirectional converter performance.

Proton exchange membrane fuel cell protection control for its hybrid power system application

Proton exchange membrane (PEM) fuel cell converts electrochemical energy directly into DC electricity without contamination emission, and its hybrid power system can cope with various load demands based on the advanced control technique. In this paper, a fuel cell protection control strategy is proposed to manage hybrid PEM fuel cell/battery power system. Firstly, a control-oriented model of the hybrid power system, involving PEM fuel cell, battery, and converters, was presented on MATLAB/Simulink. According to different external load levels, the management methods based on coordinated current- voltage control, and cascade current-voltage control, were subsequently carried out on the converters to regulate PEM fuel cell stack current, and to condition DC-link voltage. PEM fuel cell is therefore protected by current regulation regardless of external load change. Finally, to test the performance of the developed approach, experimental validation was implemented by the prototype of LabVIEW-based hybrid PEM fuel cell/battery power system.

Buck DC-DC converter design and experimental validation by time delay control

This paper presents a novel control approach based on time delay concept for buck DC-DC converter control and implementation. Time delay control is effective and useful for the voltage tracking of the buck DC-DC converter that exhibits inherent state variable variations under disturbance. To prove the voltage tracking performance improvement of the proposed method, a conventional model predictive control (MPC) is used and compared. MATLAB/Simulink models are constructed to simulate the efficiency of the controllers by comparing the system performance criteria under different operating points. Finally, experimental validations are performed and compared on the same platforms and working conditions.

Sliding-mode-control-based DC/DC converters design and implementation for hybrid proton exchange membrane fuel cell/battery power system

DC/DC converters with hybrid proton exchange membrane (PEM) fuel cell and battery power sources are designed and implemented using sliding mode control (SMC). The converters are typically comprised by unidirectional boost converter and bidirectional converter which are used for regulating the bus voltage and managing power distribution. SMC is selected to control the converters since it can cope with the high non-linear characteristic of the coupled system as well as ensure the stability. The hybrid power control system is constructed in MATLAB/Simulink platform. A comparative approach based on conventional proportional-integral (PI) control is developed to compare the control performance with SMC. The experimental validation is carried out with National Instruments (NI) LabVIEW-based hybrid PEMFC/battery supplied DC/DC converters system prototype.

Robust control for bi-directional DC/DC converter for increase of battery state of charge

Time delay control (TDC) is selected, designed and implemented in the bi-directional DC-DC converter system to supply stable DC link power to the load side. In compared with PID results, TDC can offer better performance in charging the battery or in supplying the required power without significant power loss. NEDC load profile is used to analyze the battery SOC in real-time. LabVIEW system is selected for real experimental device, and Li-ion battery is used for showing the power charging and discharging efficiency.