Jiaxi Qiang

Fuel economy and NOx emission potential investigation and trade-off of a hybrid electric vehicle based on dynamic programming

Hybrid electric vehicles (HEVs) combined with more than one power source offer additional flexibility to improve the fuel economy and to reduce pollutant emissions. The dynamic-programming-based supervisory controller (DPSC) presented here investigates the fuel economy improvement and emissions reduction potential and demonstrates the trade-off between fuel economy and the emission of nitrogen oxides (NO x ) for a state-of-charge-sustaining parallel HEV. A weighted cost function consisting of fuel economy and emissions is proposed in this paper. Any possible engine-motor power pairs meeting with the power requirement is considered to minimize the weighted cost function over the given driving cycles through this dynamic program algorithm. The fuel-economy-only case, the NO x -only case, and the fuel-NO x case have been achieved by adjusting specific weighting factors, which demonstrates the flexibility and advantages of the DPSC. Compared with operating the engine in the NO x -only case, there is 17.4 per cent potential improvement in the fuel-economy-only case. The fuel-NO x case yields a 15.2 per cent reduction in NO x emission only at the cost of 5.5 per cent increase in fuel consumption compared with the fuel-economy-only case.

An optimal torque distribution strategy for an integrated starter—generator parallel hybrid electric vehicle based on fuzzy logic control

This paper presents a systemic design method of a multi-energy management control strategy by using fuzzy logic control to realize the optimal torque distribution between the internal combustion engine and electric motor. The controller which is the brain of the hybrid electric vehicle receives vehicle information such as the acceleration and brake pedal, the engine speed, and the absolute state of charge of the battery package as inputs and sends a direct torque command to control the electric motor and the engine throttle angle to command the diesel engine. Fuzzy control logic consists of three parts to realize the interpolation mechanism: the trapezoid membership, the Mamdani rule reference machine, and the centre of gravity as the defuzzification method. A novel technique to fuzzify the vehicle torque demand that can enable a point-to-point optimization is introduced and more than 130 rules are classified into four subrule bases. Hardware-in-the-loop simulation results reveal that the efficiency of the integrated starter—generator hybrid system has been improved greatly and the fuel economy is better than the default rule-based control strategy.

The Development of A Real-Time Hardware-in-the-Loop Test Bench for Hybrid Electric Vehicles Based on Multi-Thread Technology

The hardware-in-the-loop (HIL) platform for hybrid electric vehicle in this paper features the real-time characteristic and flexibility with a simple architecture which consist of a PC to display the simulation result and calculate the model, a simulation board (HIL-ECU) to generate the analogue signals and measure the Hybrid Control Unit (HCU) output, and a USB-CAN card to implement CAN communication. The RT-HIL adopts three methods to guarantee the real-time ability: 1) utilizing the multi-thread technology based on windows operating system with high-resolution timing function to proceed the model calculation; 2) adopting high speed MCU as key component of the simulation ECU; 3) using the high speed CAN as the communication method. The multi-thread technology is a key to realize the real-time simulation by create three independent threads to handle the model calculation, the monitor-control interface and can communication in the PC without sacrificing the realtime characteristic. The HIL-ECU in this platform has a core MCU which is 32-bits single chip MC68376 form Freescale, which is a high-speed and versatile MCU with the ability to generate the analogue signals and PWM signals to replace the true sensors in practical vehicles. A hybrid vehicle model is built in the PC acting as the real engine and electric motor. The RT-HIL platform can realize the hardware-in-the-loop simulation which is a combination test the hardware and its control strategy and validate the auto-generated code to eliminate the software bugs. And it was successfully used in the ISG Diesel Hybrid development.

Model-based energy management strategy development for hybrid electric vehicles

The use of simulation packages is essential for software engineers to evaluate a specific control strategy or algorithm. This paper presents an energy management strategy development process of hybrid electric vehicles (HEV) to demonstrate the model-based development methodology. The control algorithms are modeled, simulated and optimized in the environment of Matlab/Simulink/Stateflow. A code generator, TargetLink, is used to transit the algorithm model to the embedded production ANSI C code. The generated C code is tested and modified in the hardware-in-the-loop simulation system (HIL) to ease the burden of heavy testing. The HEV energy management control strategy was developed with the model-based V-model development methodology, which guarantees the control precision and help to shorten the development time.

Battery Management System for Electric Vehicle Application

In order to solve the key technology of electric vehicle (EV), a battery management system (BMS) is proposed here to settle the critical issues. The system includes several common modules: data acquisition unit, communication unit and battery state estimation model. Two additional management units are developed here, one is thermal management and the other is high voltage management which improve the safety condition of the battery. The BMS has been successfully used in the Qi Rui Pure Electric Vehicle (QRPEV), the test results prove the validity and reliability of the system.

An adaptive algorithm of NiMH battery state of charge estimation for hybrid electric vehicle

An adaptive algorithm for battery state of charge (SOC) estimation is presented in this paper to solve the critical issue of calculating the remaining energy of battery in hybrid electric vehicle (HEV). To obtain a more accurate SOC estimation value, both coulomb-accumulation and open-circuit voltage contributions are considered in this study. The extended Kalman filter (EKF) theory which has good adaptability is used respectively in these two contributions. The adaptive control effectiveness is achieved in two aspects: one is the application of Kalman filter which can filter the noise of voltage and current measurement and the other is the open-circuit voltage correction when the battery is in steady state to compensate the deficiencies of coulomb-accumulation. The test results show this adaptive algorithm has high robust property, noise-immune ability and accuracy which is suitable for HEV application.

Fuzzy Logic Based Control for ISG Hybrid Electric Vehicle

A turbocharged diesel engine dominated integrated starter generator (ISG) hybrid electric vehicle (HEV) is proposed. In order to achieve good fuel economy and low emissions performance, a cost function which is the function of fuel economy and emissions is defined and the optimal operation line (OOL) of engine is determined through selecting the minimal value of the cost function. The baseline based fuzzy logic control strategy (BL-FLC) presented here can optimize both the fuel economy and emissions by making this compress-ignition direct-injection (CIDI) engine work at or near its OOL all the time. Also, a baseline control strategy is presented with simulation results. Compared with baseline control strategy, the BL-FLC presented in this paper can obtain 11.7% decrease in fuel consumption on the given drive cycle without sacrificing dynamic performance

An Effective Equalization Based On Fuzzy Logic for Series Moduled Battery Strings

In the lithium-ion batteries for electric vehicle applications, the battery equalizer is required to enhance life time and guarantee safety. A simple technique that provides effective equalization in terms of battery voltage for a series string of battery cells is presented in this paper. The advantages of accurate equalization are very substantial and include reduced damage to battery cells in the stack and a dramatic increase in battery life. The main circuit technique of two-level DC/DC converters substantially simplifies the structure. Moreover, fuzzy logic equalizing algorithm effectively enhances the uniformity of batteries. The operational principles and design considerations of the proposed equalizer are presented, and equalization performance is verified by the prototype with 6 Ah lithium-ion batteries.

Enhanced Performance of Electric Double Layer Capacitor as Peak Power Buffer in the Hybrid Power Source Under Low Temperature

The performance of the hybrid power source at low temperature is experimentally analyzed. The parallel connected electric double layer capacitor (EDLC) enhances the power of Li-ion battery as it acts as a buffer in charge and discharge processes, especially at low ambient temperature. The behaviors of current and voltage of both the battery and EDLC are studied by experiments and described by a mathematical model. The EDLC can share a great part of total current load at low temperature, which effectively release the battery stress in pulse charge/discharge processes. Moreover, adding an EDLC in parallel with the battery also exhibits a considerable increase in capacity as compared to the Li-ion battery standalone in pulsed and continuous discharge processes. The performance of the hybrid power source under practical drive cycle is also studied in this article.Copyright

A novel lead-acid battery management system based on generator voltage regulation algorithm

In this paper, a novel algorithm which optimally regulates the generator voltage was proposed. With this method, terminal voltage that applied on the battery was limited and optimized to an ideal range to save the electrical energy and protect the lead-acid battery from damages such as sharp charging pulse or over charging (discharging). This generator regulation model is implemented in Matlab/Simulink. Simulations performed on the dSPACE® AutoBox™ workbench verifies the logic functions of the algorithm, and the results of experiments on vehicle show that this new algorithm, compared with traditional generator control method, has more voltage set points, and it has certain contribution to the fuel economy of vehicle and battery state-of-health (SOH).