| Contactless power-supply technology overcomes the shortcomings of contact spark, carbon deposit produced by traditional power transmission. It has been widely used in many applications such as the high-power electric vehicles. However, traditional single contactless supply system can hardly adapt to the situation of high-power or multiple power levels due to the restriction on the power transformation device and transformer size. In order to meet the requirements of high power and configure the power level of system flexibly, this paper studies the dual combination contactless power supply system.Firstly, compound types of the two-channel contactless supply module are analyzed and compared in this paper. In order to bring down the input bus current ripple and expand the power capacity conveniently, the model of parallel input and serial output is chosen for the two-channel compound pattern.Furthermore, the load resistance ratio of each channel is discussed, which provides the theoretical basis for the analysis of the voltage gain and power distribution. In this paper, based on the average current of the filtering capacitor is zero in steady-state, the allocation principle of the load resistance in each channel is derived. The total load resistance ratio of each channel may not be completely consistent due to the difference of the parameters of each channel. Further, imbalance of output voltage between two channels may be enlarged, but the system characteristics of the unique solution will not make the output voltage deviation of each channel into the state of divergence. Aimed at the issue, this paper obtains the voltage gain of each channel in different frequency points by using iterative computation method and the frequency range which has the smallest imbalance in voltage gain of the combined system is given.Next, considering the cross coupling of the two-channel contactless transformers, the change of the output voltage gain and input impedance characteristics of each channel are discussed. Through mutual inductance model, because of the cross coupling, the voltage gain decreases and the increase of the equivalent impedance becomes inductive in the advanced channel while the opposite. This paper adopts the iterative computation method to get the range of voltage gain in each channel under different cross couplings and presents the frequency region which has the least cross coupling influence and the smallest difference in output voltage gain of the combined system. In order to avoid the negative influences caused by the cross coupling, from the relative position of the transformer and based on the magnetic field simulation, the arrangments having minimum coupling of each transformer is analyzed and extended to multiple compound system.Two-channel compound systems need to work in the same frequency. But applying the work mode with fixed frequency will make the two channels of system work in inductive or capacitive region due to the different parameters of the each transformer in practical application. While applying the single independent phase-locked will make each channel of the system work in different frequency, which is unsuitable for the compound system. This paper designs a alternative frequency phase-locked control scheme. On one hand, the two-channel systems can both work in inductive region. On the other hand, the problem of large circulation loss and poor efficiency can be solved when the transformer works in the deep inductive region with misalignment.Finally, two-channel, 7k W contactless power-supply system with parallel input and serial output are constructed. Then, magnetic simulations of the transformer, different placement methods, related waveforms and the value of voltage and current under different power levels and misalignment, and experimental results of the alternative frequency phase-locked are given in relevant parts of this paper. When the air gap is 20 cm and output power is 5.6k W, the efficiency of the system can reach 94.7%. |
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