Minggao Ouyang

Dynamic Programming Algorithm for minimizing operating cost of a PEM fuel cell vehicle

A PEM (Proton Exchange Membrane) fuel cell city bus utilizes a PEM fuel cell engine as the primary source, and a li-ion battery system as the auxiliary power source. By optimizing the power split strategy and recycling braking energy, this kind of power-train has advantages of zero emission and high energy efficiency. However, the cost of hydrogen gas is far more expensive than that of the electric energy. How to split the power between the two power sources so as to minimize the operating cost, as well as guarantee the vehicle dynamic performance, becomes an important topic. This paper proposes a Dynamic Programming Algorithm (DPA) to solve the minimizing problem. Some details of the DPA are discussed, e.g. the principles of selecting parameters for the algorithm. The effectiveness of the algorithm is verified by comparing simulating results of different algorithms. Results show that, 1) by using the DPA algorithm, we can find the optimal control strategy in an objective way. 2) The constraints of vehicle dynamic performance on the optimal problem have great influences on the optimal results. 3) To predict the power requirement in the near future is very important to achieve an optimal real-time strategy.

Research on hub motor control of four-wheel drive electric vehicle

The Four-wheel drive electric vehicle (EV) is driven by four hub motors. In the hub motor drive system, three hall-effect sensors are usually used to provide absolute rotor position information, correspond to the block commutation algorithm for BLDC motors. However, the waveform of the back electromotive force (EMF) of the hub motor is not trapezoidal, but between sinusoidal and trapezoidal shape. The amplitude of the torque ripple at low speed is large and the frequency is close to resonant frequency. As a result, when the EV drives at low speed, the noise is serious. A sinusoidal current drive system of sinusoidal-wave PM motor with a low resolution position sensor is proposed in paper [1]. At low speed, the performance of the sinusoidal current control is perfect, and the torque ripple is much lower than that of the block commutation algorithm. However, the noise increases at middle and high speed because of the switching noise and harmonics. This paper proposes a combined BLDC and PMSM control for the hub motors. Sinusoidal control or field oriented control is applied for the hub motor at low speed, while block commutation algorithm is used at middle and high speed. A low noise level of the driving cab in all speed range can be reached. The electric braking method for the Four-wheel drive EV is also introduced. The proposed methodology is demonstrated by vehicle test, and is shown to achieve low noise level and dynamic performance.

General status & new target of 863 programme on HEV/EV in China

China Ministry of Science & Technology of China (MOST) had been planed 3 five year Chinese hi-tech national R&D program (863 programme) on the area of HEV and EV, including the fuel cell vehicles since 2001. The plan involved the main R & D research institutes, manufactories and universities related to automotive industry in China. This paper briefly introduced the past two-5-year plan and mainly report the next 5 five year plan since 2011. The challenges of the HEV and EV was introduced, and roadmap of future China EV strategy was outlined, which could be start from city bus (large size vehicle, insensitive to weight and mile range) and low speed micro-vehicle (small and compact size, low speed, short distance applications), then would be developing towards the general passenger cars. Typical clean vehicle powertrain, include hybrid fuel cell city bus, plug-in passenger car, and four wheel motor drive micro-EV was introduced and discussed.

Integration of PEM fuel cell/battery powertrain: EMI noises and power split strategy

EMI (electromagnetic interference) noises and power split strategy are two important topics when integrating a PEM fuel cell/battery hybrid power-train. Principles and methods to eliminate the EMI noises are firstly introduced. Generally speaking, the EMI noises can be reduced by applying electrical grounding, designing a time-triggered communication system and using some filter technologies in electric control units. A power split strategy on the basis of a prediction algorithm is then proposed aiming at prolonging working life time of fuel cell stacks. With this strategy, the fuel cell stacks work in a quasi-steady state and the battery is kept charge-sustaining. Experimental results show the effectiveness of the strategy.