The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimatin...
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The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimating method is widely used to design the main circuit. In order to guarantee the whole system works safely and improve utilization rate of devices, the concept of SSOA (systematic safe operating area) is presented. By determining the relationship of key parameters between devices and converter, the expression of SSOA is described quantitatively. Then it is implemented as a basic rule to design a back-to-back converter based on IGBT for 55kW induction motor optimally. Rated value of DC-link voltage and grid filter of the system is obtained reasonably as well.
IPS has many special characteristics, such as using multi-phase, multi-frequency and hybrid AC/DC devices. As a result, existing electromagnetic transient simulators developed for power systems on land do not apply to...
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IPS has many special characteristics, such as using multi-phase, multi-frequency and hybrid AC/DC devices. As a result, existing electromagnetic transient simulators developed for power systems on land do not apply to IPS. This paper aims to build up a parallel based real-time electromagnetic transient simulator for IPS. A fast multi-switching process method for parallel electromagnetic transient simulations is coined to handle the tremendous switch events in IPS. To solve the difficulties brought by multi-phase machines in IPS, a multilevel hybrid parallel algorithm is forged through the combination of component level and network level parallelization. Based on the key techniques mentioned above, a parallel simulator is built up. Through sufficient testing to typical examples of IPS, the accuracy and high-efficiency of the simulator are proved.
Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance...
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Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance of the DC bus bar, have significant influence on the switching process, electromagnetic interference and component stress of the semiconductor switches. It becomes one of the key points for the safe operation of inverters. Based on an actual 55 kW inverter, the design, simulation and analysis for its bus bar is described in this paper. The bus bar model is built with the method of Partial Element Equivalent Circuit (PEEC), and the stray parameters are extracted from PEEC model and applied in the circuit simulation. Compared with the experimental results, the modeling validity is proved, and the simplified modeling process and design principles for complex physical bus bar are presented.
The active control system of pipeline noise of engine exhaust is a time-varying systems, that includes a sub-channel identification. The tracking in time plays an important role, and that is a hardcore of algorithm fu...
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The effects of fuel octane number(RON) on homogeneous charge compression ignition(HCCI) combustion were studied under different combustion boundary conditions on a rapid compression machineThe results show that the ma...
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The effects of fuel octane number(RON) on homogeneous charge compression ignition(HCCI) combustion were studied under different combustion boundary conditions on a rapid compression machineThe results show that the maximum pressure raise rate and maximum combustion temperature decreased as the RON increased while the start of combustion is delayed and the combustion duration is shortened at the same time.
First, this study presents the concept of heavy equipment transport and the existed problem of turning at bend. Then, considering the characteristics of heavy equipment transport and through preliminary technique anal...
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First, this study presents the concept of heavy equipment transport and the existed problem of turning at bend. Then, considering the characteristics of heavy equipment transport and through preliminary technique analysis and hypothesis, make a dynamic model of the vehicles and cargoes and modify it according to its potential problems. In the end, to take the practical conditions of heavy equipment transport for an example, simulate the turning path of it at the intersection, come to some conclusions at the same time and verify the validity of the model.
In this paper, we consider the vehicle online motion planning for the avoidance of emergency situations under structured environment as the object of our researching. In the framework of MPC, a motion planning method ...
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A new type electro-hydraulic variable valve actuation (VVA) system is developed to realize homogeneous charge compression ignition (HCCI) combustion with different exhaust gas recirculation (EGR) strategies on a low s...
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A new type electro-hydraulic variable valve actuation (VVA) system is developed to realize homogeneous charge compression ignition (HCCI) combustion with different exhaust gas recirculation (EGR) strategies on a low speed single cylinder research engine. Power supply pressures and hydraulic piston geometries of the VVA system were firstly determined. Main orifice diameters for fluid charge and discharge were numerically studied with AMEsim software to figure out their optimal values. A damper system and a multi-discharge-orifice mechanism were designed to provide better solutions for actuator braking and for valve seating velocity reduction, respectively. Bench tests indicated that this system was capable to achieve flexible valve motions, such as variable valve timing, duration and lift, with dramatically improved valve lift overshoot and effectively reduced valve seating velocity at the full range of research engine speed. Experiment results revealed that this VVA system could be used to realize robust HCCI combustion by means of different EGR strategies.
Conduct interior vehicle acoustic quality evaluation to improve automobile comfort is very important significance. This paper introduces the BP neural network application in the vehicle acoustic quality prediction, an...
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Conduct interior vehicle acoustic quality evaluation to improve automobile comfort is very important significance. This paper introduces the BP neural network application in the vehicle acoustic quality prediction, and set up a sound quality of prediction model with BP network. The network was trained using variable learning rate back propagation algorithm. Interior vehicle sound quality was analysed and predicted by using trained neural network model, and then prediction results are analysed. simulation results indicated that neural network prediction results are close to subjective evaluation score, and has little error and good prediction or generalization ability in the prediction of sound quality.
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