Hu Zhong

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.

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.

Power Distribution and Coordinated Control for a Power Split Hybrid Electric Bus

The power distribution is proposed to determine the target operating points of the system components as the basis for maximal the efficiency of the overall system for a power split dual electric machine hybrid electric bus. The coordinated control is constructed on the basis of the power distribution. The basic coordinated control is implemented to satisfy the drivers power demand, in which both the dynamic characteristics of the engine and the dual electric machine are explicitly taken into account. Moreover, the improved coordinated control is suggested to suppress engine dynamic operation and rich fuel injection.

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

Principles and application of the real-time hardware-in-the-loop simulation platform based on multi-thread and CAN

This paper introduces the principles, construction and application of a novel real-time hardware-in-the-loop simulation (RT-HILS) platform. The RT-HILS consist of a PC to display the simulation result and calculate the model, a HIL board to generate the analogue signals and measure the output of the target ECU, and a USB-CAN card to implement CAN (controller area network) communication. Multi-thread technology is used to control the modelspsila calculation step to guarantee its real-time characteristics. The CAN with the speed of 500 Kbit/s is also important to real time simulation. The models and communication functions are cooperated into the LabView by its DLL node. The RT-HILS platform has applied to the diesel engine controller and hybrid vehicle controller. An example of the application of RT-HILS to the development of HCU (hybrid control unit) is presented to show the functions of RT-HILS.

Development and performance validation of an ISG diesel hybrid power-train for city buses - part II: Control strategy and road test

This is the second part of the two-part paper to illustrate the control system design and multi-energy strategy, it is the key to fulfill the fuel economy target for ISG hybrid bus. Based on a hierarchical structure, the control system is developed with the HCU (hybrid control unit) as the central controller to coordinate the motor, engine and CAN communication protocol. The multi-energy control strategy is consisted of the auxiliary strategy and the main strategy. The first one includes the finite state machine which decides the turning-point from one state to another state and the 2-quad tree of expert system which is adopted to realize the automatic start/stop function; the last one is called as the torque distribution strategy that satisfies the drive demand as well as implements the optimal torque distribution by fuzzy method. The parallel regenerative brake strategy and self-adaptive SOC balance strategy are all cooperated into the fuzzy based torque distribution strategy. The road tests are done to test the performance of ISG power-train and to validate the functions of the control system. The result shows that the fuel economy is 25% better than the traditional bus.

Development and performance validation of an ISG diesel hybrid power-train for city transit buses - part I: Parameter matching and system integration

This two-part paper presents the development an ISG diesel hybrid power-train to provide a solution for the city transit buses. The ISG power-train which adopts the ISG parallel configuration which is inserted a thin but powerful motor between the engine and the flywheel is a compact and flexible power-train with high efficiency and sufficient power. The drive demand of Chinese typical city cycle is analyzed and the key componentspsila parameters are deduced using the classic vehicle dynamic equation. The design of permanent magnetic motor and its controller are introduced in details and the system integration is illustrated as well. The control system and the multi-energy strategy that are the key to realize the fuel economy target will be introduced in the part II. The bench test of ISG diesel power-train is conducted to test the maximal performance and to validate the functions of ISG motor.