Yimin Gao’s research while affiliated with Texas A&M University and other places

This paper systematically discusses the design and control methodologies of a plug-in hybrid electric vehicle (PHEV). Design methodology is focused on battery energy and power capacity design. Two kinds of typical batteries, namely, NiMH and Li-ion, are discussed. Control strategies focus on all electric range and charge depletion range operations. In addition, a constrained engine on and off control strategy is discussed for charge-sustained operation. Simulation has been performed for an example passenger car. The simulation results indicate that a significant amount of fuel can be displaced by electric energy in typical urban driving.

In this paper, an ultracapacitor boosted hybrid fuel cell vehicle drive train has been introduced, in which, fuel cell provides basic power and ultracapacitor provides peaking power to meet load demand. A unidirectional boost DC/DC converter couples the fuel cell to the DC bus, and a bidirectional buck/boost converter couples the ultracapacitor to the DC bus. The system parameters have been designed, which includes, traction motor power rating, fuel cell power and ultracapacitor energy capacity. A control strategy has been developed for controlling the fuel cell to operate in its high efficiency region and the ultracapacitor to deliver peaking power to meet the load demand. Simulation has been performed to verify drive train performance for full load acceleration and speed varying driving pattern.

A regenerative braking system with simple structure, high efficiency, good performance and easy control is crucial for electric vehicle (EV), hybrid electric vehicle (HEV) and fuel cell vehicle (FCV). SR machine is one of the promising candidates. In this paper, the current and torque performance of a SR machine for application to vehicle regenerative braking has been studied. The relationship between the torque, speed, turn-on and turn-off angles has been established. The data obtained through simulation is very useful for vehicle control design.

This paper focus on the harmony control of chopping frequency at low speed range in which SRM operates with voltage-PWM mode in time and frequency domains. The simulation results indicate that the total distribution of spectrum of phase current on nth harmony frequencies keeps the same shape when the ratio of chopping frequency to shaft speed is constant. Thus chopping frequency and shaft speed can be harmony controlled by applying a proper chopping frequency-speed ratio. The phase current fluctuation is decreased with the increase in chopping frequency at a constant shaft speed. The torque output capacity tends to be decreased with increase in the chopping frequency. The decreasing rate with respect to chopping frequency in the low chopping frequency range is larger than that in the high chopping frequency range. The torque output capacity of SRM tends to be constant when the chopping frequency is high enough. In practice, the chopping frequency applied that is close to the natural frequency of the stator should be avoided.

A PC-based-air-ABS-HIL-simulation test bench with low cost and high efficiency is presented in this paper which can be used to developed air-ABS for commercial vehicle. It has been developed in Matlab/Simulink environment with the real-time rapid prototyping tool: xPC target. The architecture, hardware, and software of this test bench are described in details. Utilizing the test bench, the real-time HIL-simulation tests for air-ABS have been completed. The results illustrate the effectiveness and applicability of the developed test bench.

Due to the introduction of electrical regenerative braking, the structure, design and control of braking system of an electric vehicle (EV), hybrid electrical vehicle (HEV) and fuel cell vehicle (FCV) is quite different from the pure mechanical braking system of conventional vehicles. Desirable braking performance not only guarantee to quickly stop the vehicle and maintain the traveling direction stable and controllable, but recapture the braking energy as much as possible on various conditions of road. In this paper, the braking energy characteristics on vehicle speed and braking power in typical urban driving cycles have been investigated. The results provide strong supports to the design and control of such hybrid braking system. Two hybrid braking systems have been introduced. One is parallel hybrid braking system, which has a simple structure and control. The other is fully controllable hybrid braking system. Two typical control strategies for this system have been established. One emphasizes optimal braking performance and the other on optimal braking energy recovery.

As the most key parts of pneumatic Antilock Braking System (ABS) for commercial vehicle, the dynamic characteristics of pneumatic ABS solenoid valve directly influence on the effectiveness of ABS. Modeling and simulation of pneumatic ABS solenoid valve is presented in this paper on the top of MATLAB/ SIMULINK, Hardware in the Loop (HIL) test bed of pneumatic ABS is developed, and the test of dynamic characteristics of pneumatic ABS solenoid valve is completed. Based on the results of simulation and test, the factors which influence the dynamic characteristics of solenoid valve is analyzed, and the design guideline of solenoid valve is brought forward.

EBS (electronic brake system) can effectively control and adjust braking force acting on every wheel, reduce braking response time and braking distance, and make vehicle achieve much more braking stability. It is featured with CAN (Controller Area Network) communication by which the sensor signals and control command signals can be transmitted and received. In the braking performance test of EBS, conventional test methods have some inconvenience in existence. For example, the fixing of pressure sensors and wheel speed sensors is restrained by the installation position, and the precision of measuring is prone to be affected by the environment conditions. But based on CAN communication technology, the special testing instrument can be connected with CAN bus, monitoring and recording signals on the bus. Thus signals representing braking performance can be acquired through CAN bus.

Electric traction is one of the most promising technologies that can lead to significant improvements in vehicle performance, energy utilization efficiency, and polluting emissions. Among several technologies, hybrid electric vehicle (HEV) traction is the most promising technology that has the advantages of high performance, high fuel efficiency, low emissions, and long operating range. Moreover, the technologies of all the component hardware are technically and markedly available. At present, almost all the major automotive manufacturers are developing hybrid electric vehicles, and some of them have marketed their productions, such as Toyota and Honda. This paper reviews the present technologies of HEVs in the range of drivetrain configuration, electric motor drives, and energy storages

Batteries and ultracapacitors have significantly different energy storage and power delivery capabilities. Electrical traction motors in hybrid electric vehicles have characteristic power and energy demands, and a single energy storage technology may not be optimized to meet both the minimum power and energy demands. In this paper, we investigate the effect of combining batteries and ultracapacitors, both actively and passively, to produce a more versatile electrical energy storage system for hybrid electric vehicles. Hybridized energy storage systems result in increased component life cycles, decreased internal resistance losses, and reduced cost and mass when compared to either battery-only or ultracapacitor-only configurations