Yuedong Zhan

Fuzzy neural network-based model reference adaptive inverse control for induction machines

In this paper, because the induction machines are described as the plants of highly nonlinear and parameters time-varying, in order to obtain a very well control performances that a conventional model reference adaptive inverse control (MRAIC) can not be gotten, a fuzzy neural network-based model reference adaptive inverse control strategy for induction motors is presented based on the rotor field oriented motion model of induction machines. The fuzzy neural network control (FNNC) is incorporated into the model reference adaptive control (MRAC), a fuzzy basis function network controller (FBNC) and a fuzzy neural network identifier (FNNI) for asynchronous motors adjustable speed system are designed. The proposed controller for asynchronous machines resolves the shortage of MRAC, and employs the advantages of FNNC and MRAC. Simulation results show that the proposed control strategy is of the feasibility, correctness and effectiveness.

A PEMFC/Battery Hybrid UPS System for Backup and Emergency Power Applications

This paper presents the development of a proton exchange membrane fuel cell (PEMFC) and battery hybrid uninterruptible power system (UPS) for backup and emergency power applications. A sixty-cell PEMFC stack is employed as the main power source at normal load and a 3-cell lead-acid battery is employed as the auxiliary power of the UPS at overload or during the PEMFC startup. The PEMFC consists of two valves for the hydrogen input and output respectively, a mass flow controller to adjust the hydrogen mass flow, and a pressure sensor to control the hydrogen pressure, and their control units for the management of the whole system. The design procedures of the UPS hybrid system are discussed. Experimental setups are presented and the experimental results verify the performances of the PEMFC/battery hybrid power source and the UPS system under the condition of computer load. The developed UPS system proves to be a cost-effective solution for backup and emergency power applications.

Design of an active power factor converter for ups with backup proton exchange membrane fuel cell/battery

In this paper, a 300 W boost active power factor corrector (PFC) for single-phase high frequency uninterrupted power supply (UPS) with universal input and fixed output voltages is analysed and then designed for backup and emergency power applications. The UPS is supplied by a backup proton exchange membrane fuel cell (PEMFC) and battery hybrid power source, in addition to the main source. The principle and structure of the active PFC are introduced and discussed. Based on the idea of adopting mature technologies, key practical techniques of the design are presented, including the control technique of the active PFC and the design of the boost inductance, capacitances and external circuits. Experimental results show that the active PFC can achieve a fixed output voltage of plusmn380 VDC within a wide range of input voltage. It owns the advantages of high efficiency, high power factor as close to 1, and total harmonic distortion of less than 5%.

Fault monitoring and control of PEM fuel cell as backup power for UPS applications

This paper presents the expert fault monitoring and intelligent comprehensive control of a proton exchange membrane (PEM) fuel cell (PEMFC) as backup power source for an uninterruptible power supply (UPS) system. The failure status can be shown on the screen of a micro-computer (or a PC) linked with the UPS through an RS-232 and on the control panel of the UPS through LED indicator lights. The proposed intelligent comprehensive monitors and controllers of PEMFC and UPS can supply high quality power with flexible conversion functions, leading to the establishment of reliable power management for UPS applications. Finally, a suitable strategy and technique of fault monitoring and control for a UPS hybrid system with backup PEMFC and battery is implemented. The performances of the monitors and controllers are evaluated by experimental results, showing that the developed UPS system with backup PEMFC and battery power sources is suitable for industry applications.

Rotor field orientation speed and torque control of BDFM with adaptive second order sliding mode

This paper presents two cascaded second order sliding mode controllers (SOSMCs) for brushless doubly fed motor (BDFM) adjustable speed system, which regulate the speed and torque. And an adaptive super twisting algorithm is incorporated into the SOSMCs to adaptively regulate the law of SOSMC. The proposed controllers for BDFM eliminate the average chattering encountered by most sliding mode control (SMC) schemes, and also possess the robustness and excellent static and dynamic performances of SMC. Simulation results show that the proposed control strategy is feasible, proper and effective.

Modeling and control of power converters in UPS applications with PEM fuel cell

This paper investigates practical cost-effective DC/DC converter, DC/AC inverter and AC/DC rectifier for an uninterruptible power supply (UPS) system with backup proton exchange membrane fuel cell (PEMFC). The developed power converters can supply high quality power with flexible conversion functions, leading to the establishment of reliable power management for UPS applications. A comprehensive control strategy of the PEMFC is implemented for energy management of the UPS hybrid system. The performances of the proposed power converters and their controllers are evaluated by experimental results, showing that the developed UPS system with backup PEMFC and battery power sources is suitable for industry application.

Input current ripple reduction and high efficiency for PEM fuel cell power conditioning system

To solve the issues of the open-loop control accuracy in a proton exchange membrane (PEM) fuel cell power conditioning system (PCS) with active clamp push-pull DC/DC converter for input current ripple reduction, a novel closed-loop digital-controlled method is proposed. The proposed PEM fuel cell PCS consists of a high-efficiency high-step-up current-fed resonant push-pull DC/DC converter and a half-bridge inverter. A fully digital-controlled strategy in the active-clamped circuit is employed to reduce the voltage spike and low frequency current ripple (LFCR) on the power switches for improving the lifespan of PEM fuel cell and raising the system reliability. By using the closed-loop current ripple reduction control, the LFCR is further reduced. A 300 W prototype is implemented and tested. Experimental results show that the minimum efficiency at full load is about 94.8% and the ripple current is less than 1.2% of the rated input current.

Control of redundancy PEM fuel cells in UPS applications with improved performance and durability

To guarantee the reliable operation of 24 hours, improve the performance and durability of a proton exchange membrane fuel cell (PEMFC) stack, and prevent it from sudden failure in an uninterruptible power system (UPS) with hybrid backup redundancy PEMFCs, battery and supercapacitor (SC) power sources, this paper conducts research in smart power management and control strategy of two PEMFCs and UPS. Firstly, based on the analysis of the major degradation mechanisms of different components of PEMFC against the operation conditions, two PEMFCs are proposed and applied to the UPS system. The experimental results show that the proposed intelligent energy management and control strategy can effectively guarantee the power sources supplied to UPS, and automatically switch the power supply between two PEMFCs.

Intelligent comprehensive control and monitor of Proton Exchange Membrane fuel cell for hybrid UPS system

This paper, to improve the performance of a Proton Exchange Membrane fuel cell (PEMFC) stack, avoid the hydrogen and oxygen/air starvation of electrochemical reaction and the performance deterioration of the stack, prevent the dehydration and drying of the membrane, keep the water content in the membrane, heighten the utilization of the gases, and track the output power of a hybrid uninterruptible power supply (UPS) system with backup PEMFC and battery power sources, conducts research in the dynamic model, the on-line parameters monitoring of PEMFC, such as the resistance in the PEMFC stack using the current interrupt method and the performance improvement of the PEMFC employing an intelligent comprehensive control strategy of the operation parameters, such as operating temperature, pressures and mass flows of hydrogen and air, the output current and voltage for the PEMFC stack, the power supply switching between PEMFC and battery. The intelligent comprehensive control and monitor method is proposed and applied to the PEMFC generating system employed for the power source of UPS. The experimental results show that the proposal method can effectively monitor and control the pressures of the inlet hydrogen and the operating temperature of the stack, automatically switch the power supply between PEMFC and battery, efficaciously prevent the destroy of the stack when the load changes sharply, the hydrogen is purged and the output current is interrupted regularly, and reasonably improve the performance of the PEMFC through the water balance and thermal management, and real-time realize the tracking for the changes of the output power and the distribution of the mass flow rates of hydrogen and air.