Research Of Zero-Voltage-Soft-Switch Technology Of Maglev Train Chopper

Maglev chopper is the key component of maglev train. This paper mainly designs a novel Zero-Voltage-Soft(ZVS) switching DC/DC chopper and validate on experiment which could be have abroad application in maglev, that is based on the study object of low and middle speed electromagnetic-suspension(EMS) maglev.Now, the traditional H-bridge maglev chopper had been widely used in practice, which had much merit, such as the simple structure and reliable quality. However, the H-bridge maglev chopper has serious switching losses, so as to have snubber circuit; there is high EMI with the chopper. So, we need to study other novel chopper structure for loosening the losses in switching and developing the efficiency and reliability. Based on the traditional chopper, in view of the characteristics of the Boost-chopper for providing the ZVS switching condition, then, we have a novel ZVS switching DC/DC chopper.This paper analyzes the characteristics of ZVS switching chopper, and introduces the design of the basic parts of the chopper. The last part is the result of the simulation and experiments in detail. Compared with the traditional chopper, the novel chopper has its particular excellence, though we can find some shortage in it.First of all, the main-switches of the ZVS chopper have zero-voltage turn-on and turn-off totally, so it has little switching losses. For this, the efficiency of the chopper can be improved. The second, the realization of the ZVS has no concerned with the attribute of load. With the load of light or full, even the resistance or inductor load, the chopper can ensure that the main-switches will realize the ZVS switching. But, there is little thing in the harvest, as the chopper provides the ZVS condition with an assistant switch, which work in hard switching, it has some losses in switching even using a snubber network. There is another more, the snubber can be resonant with the inductor, that brings on a huge spike on the source voltage. Above all, the defects cannot obscure the virtues, this novel ZVS chopper is a preferable chopper structure, which can be applied in maglev chopper broadly.With the development of modern power electronics, maglev chopper should be perfect incessantly. In the future, we should step forward to study how to minish the voltage spike, to improve the assistant switch network, to study another new structure topology, for enhancing the capability of the maglev chopper.