Wei Gu

Frequency splitting phenomena are investigated systematically by circuit theory in a series-tuned contactless power transfer (CPT) system. First, in a symmetrical CPT system, the splitting equation is defined and the key frequency splitting characteristics are described by the trough and the ridge equations in a complete fashion. The even and the odd splitting frequencies are exactly two roots of the ridge equation; the splitting coupling is determined theoretically when the even and odd splitting frequencies merge together. Second, in an unsymmetrical CPT system, the idea of the trough and the ridge equation is exploited to find exactly the splitting coupling. Next, the relationship between frequency bifurcation and splitting is elucidated; and a zero-phase control method is suggested to track the splitting frequency when the coupling changes in the splitting region. Finally, the theoretical results are validated by a 10-W prototype with planar spiral coils.

An asymptotic coupled-mode theory (CMT) method is used to analyse the frequency splitting phenomena in contactless power transfer (CPT) systems. Theoretical analysis and experimental results show that the CMT method catches the key pitchfork characteristics of the frequency splitting phenomena, and a concise expression is derived to relate the splitting point to all key system parameters.

Rubber tyred gantry (RTG) cranes are an important piece of transport equipment in ship and rail container terminals. They have a diversified power demand, for example, peak powers of 292-kW driving, 178 kW regenerating, and 7-kW idle power. The high peak power demand determines the system prime mover (internal combustion engine) rating, which is highly over-rated for the crane average energy requirements. Such a variation in peak to idle power demand favors a hybrid power solution which, given appropriate design, can yield significant gains in fuel or energy usage and, importantly, reductions in local emissions, thus improving air-quality. In this study, a hybrid energy source for an RTG crane is presented. The hybrid energy source comprises of a lithium battery and a down-sized diesel-generator connected to the dc link through an active front end unit. While other systems have been previously proposed, the system presented here utilizes a smaller diesel-generator, thus reducing plant and fuel consumption. In addition, the battery connects directly to the dc link reducing system power electronics while improving battery response and efficiency. Experimental results from a full-size evaluation system are presented showing a 57% reduction of fuel consumption compared to a conventional RTG crane system.

Based on analyzing the magnetic leakage feature of wire rope defects, the longitudinal resolved vector B/sub ot/ of the defect leakage field is taken for the object to be tested. In order to detect the weak magnetic leakage field, a fluxgate sensor of single core and single winding is developed. Using the fluxgate, a new kind of transducer for testing defects of wire rope has been designed. The structure and interface circuit of the transducer are studied. The experimental results of detecting the LF and LMA defects of the wire rope are presented.

In order to ensure the operation safety of the lithium battery hybrid rubber-tired gantry (RTG) crane, the dynamic power control of the lithium battery hybrid RTG crane is studied. This paper introduces the construction and switching modes of the lithium battery hybrid RTG crane. The generator set will not turn on/off frequently using the power management strategy with max on and off, especially in the hybrid system with high-capacity battery and small size of diesel engine generator set. The high-power lithium battery is a better choice for RTG because it reduces emissions on the port. The dynamic model of the hybrid RTG crane is established, and the operation characteristics in different modes are analyzed. The safe operation is realized through the coordinated control load power, battery power, and the diesel-generator power. The warm-up time and cool down time of generator set are considered in the power management strategy with max on and off for a series hybrid system for the first time. The hybrid RTG crane characteristic and the energy saving are verified through the experimental data. The cost of charging the battery is analyzed, revealing that the new RTG saves 70% compared to the conventional RTG crane.