Haiping Xu

Fuel cell power system and high power DC-DC converter

This paper discusses the principle and electrical characteristics of the fuel cell, designs an innovative hybrid power system, and proposes a new DC/DC converter scheme to combine the fuel cell with the storage system. An effective converter scheme for the fuel cell is obtained by analyzing the high efficient topology as well as the phase shifted pulse-width modulation. Through comparing several different control modes of converters, a 75-kW prototype system is constructed, moreover, which steady-state operating characteristics are illustrated and discussed in detail. At last, experimental results are also shown to verify the proposed scheme.

Analysis and Design of High Power Interleaved Boost Converters for Fuel Cell Distributed Generation System

This article proposes a novel topology of high power interleaved boost converter for fuel cell. With thorough analysis of the operating principle of the converter, eight equivalent sub-circuits are described. According to the waveforms of the inductor current, the operation modes of the converter are classified to six kinds, including CCM (continuous conducting mode) and DCM (discontinuous conducting mode), and the uniform state-space averaged model of the converter in CCM and DCM are developed. Based on the transfer function, the two-loop controllers are designed, and a prototype of 150 kW converter that is controlled by DSP-320F2407 is constructed. The volume and weight of the proposed converter are decreased 1/3 than conventional converter and the efficiency is over 97%. The experimental results show that the converter has excellent electrical characteristics, and it can be applied in the fuel cell distributed generation system

Analysis and design of Bi-directional Z-source inverter for electrical vehicles

A new topology bi-directional Z-source inverter is proposed. It can overcome the uncontrollable and unstable limitations of the Z-source inverter in DCM mode. The operational principle, design guidelines of Z-source networks and power devices are provided. A DC clamp snubber circuit is developed to limit the voltage spike on power device. Power loss analysis and 3-D design for Z-source inverter system are presented. A prototype of 55 kVA bi-directional Z-source inverter is designed to verify the principle and performance of the proposed topology.

High Power Interleaved Boost Converter in Fuel Cell Hybrid Electric Vehicle

This article presents the fuel cell electric vehicle (FCEV) power supply system configuration, and proposes a topology of high power interleaved boost converter for fuel cell. With thorough analysis of the operating principle of the converter, eight equivalent sub-circuits are described. According to the waveforms of the inductor current, the operation modes of the converter are classified to six kinds, including CCM (continuous conducting mode) and DCM (discontinuous conducting mode), and the uniform state-space averaged model of the converter in CCM and DCM are developed. Based on the transfer function, the two-loop controllers are designed, and a prototype of 150 kW converter that is controlled by DSP-TI320F2407 is constructed. The volume and weight of the proposed converter are decreased 1/3 than conventional converter and the efficiency is over 97%. The experimental results show that the converter has excellent electrical characteristics, and it can be applied in the FCEV as well as the fuel cell distributed generation system

Interactive charging strategy of electric vehicles connected in Smart Grids

Electric vehicles (EVs) represent an important future load on the electric utility system which, if implemented in a large scale without control, may lead to grid problems such as power losses and voltage deviations. However, if properly managed, it could increase power plant utilization and reduce the average cost of generating electricity. This paper proposes and analyzes two novel interactive charging strategies for scales of electric vehicles connected in Smart Grid. The first decentralized approach is controlled directly by the electric vehicle charging controller. Six charging modes included in this strategy adjust schedule of electric vehicles charging operation automatically and ensure the charging orderly. The other is centralized charging strategy. With the aim of minimizing power losses and voltage deviations, the optimal algorithm in charging management system also takes into consideration not only the information like current SOC, the battery capacity and connecting time but also the electricity grid constraints. Both of them optimize EVs charging schedules and charging rates. In addition, a two-way communication network based on Zigbee and other communication technology is established to ensure the implement of the interactive charging control. The success of this charging strategy can be an important theoretical meaning and promotional value for EV.

High power DC-DC converter and fuel cell distributed generation system

This paper discusses the principle and electrical characteristics of the fuel cell, designs an innovative hybrid power system, and proposes a new DC-DC converter scheme to combine the fuel cell with the storage system. An effective converter scheme for fuel cell is obtained by analyzing the high efficient topology as well as the phase shifted PWM. Through comparing several different control modes of converters, a 75 kW prototype system based on DSP is constructed, moreover, which steady state operating characteristics are illustrated and discussed in detail. At last, experimental results are also shown to verify the proposed scheme.

Control algorithm research on seamless transfer for distributed resource with a LCL filter

Generally distributed resource (DR) with LCL-based grid inverter works as controlled current source in grid-connected mode, while operates in controlled voltage source in island. So in case of utility faults or intentional islanding, DR has to change its control strategy from controlled current source to controlled voltage source. This paper analyzes the transition between controlled current source and controlled voltage source on single-phase inverter and three-phase inverter, respectively, and then presents a novel control strategy based on controlled voltage mode whether connected to the grid or in stand-alone. Once the grid failure, this control strategy regulates the inverter output voltage amplitude quickly, which forces the grid currents through the SCR switches to decrease to zero at much less time and during this SCRs turn-off period, the voltage fluctuates within permissible levels. After disconnection from the grid, the inverter will recover its voltage amplitude to a rated level. The algorithm is discussed in this paper detailedly. Computer simulation and experiments proved the feasibility of this control scheme.

Study on isolated boost full bridge converter in FCEV

Fuel cell engine cannot provide enough power at cold start. According to these, a 5 KW isolated boost full bridge (IBFB) converter is developed as the auxiliary power supply. With the IBFB converter, the 24 V DC of the auxiliary storage cell of the fuel cell electric vehicle (FCEV) is converted to a stabilized 300 V high DC. The IBFB converter is controlled with a double voltage and current loop based on DSP- TMS320LF2407. Experimental results show that the system has excellent properties and can be used in areas like FCEV

A unit power factor DC fast charger for electric vehicle charging station

Widely applications of electric vehicle rely on popularization of charging station. With the increase in the number of charging station, the problem of grid pollution becomes worse and worse, and the charging hours must be decreased to raise the utilization rate of electric vehicle. This article proposes a novel unit power factor DC fast charger for electric vehicle charging stations. This DC fast charger, mainly used in fast-charging station, includes two modules: the input module is three-phase PWM rectifier and the output module is the phase-shift full-bridge converter. The two modules are controlled by only one DSP - TMS320F2812. The three-phase PWM rectifier overcomes traditional rectifiers shortcomings of low power factor and large harmonic, and is higher power than three-phase one-switch or two-switch power factor correction circuit. The phase-shift full-bridge converter is the isolated high-frequency DC-DC converter, and apt to be used in high power situation. Furthermore, the volume and weight of the proposed charger are decreased than conventional converter with grid-frequency transformer. A prototype of 10 kW Charger is constructed. The experimental results show that the novel DC fast charger has excellent electrical characteristics, and it can be applied to the electric vehicle charging stations.

Research of smart charging management system for Electric Vehicles based on wireless communication networks

With the rapid development of Electric Vehicles (EVs), large-scale charging requirement will heavily impact the existing power grid. So there is an urgent need for coordinating control to avoid it in smart grids. Demand side management reducing charging rate at peak load and rescheduling charging process at appropriate time such as low grid load can be used to solve this issue. This paper proposed a coordinating control charging management system for EVs charging station, which is comprised of single-node charging controllers and a centralized management system. Electric Vehicle Charging Controller (EVCC) implemented via PWM signal to control charging current and charging time. As a crucial component of centralized control, Smart Electric Vehicles Charging Management System (EVCMS) obtains charging data and transmits control instructions via ZigBee and GPRS wireless communication networks technology. For calculating the charging current that each EV needs, a model of battery State-Of-Charge (SOC) is included, and each EVCC gets initial battery SOC, battery capacity and other data through CAN-Bus. In the end, the design of ZigBee and GPRS is discussed, and this two-way wireless communication networks is low power consumption, small size, high reliability, and easy expansion.