The Research On Smoothness Of Contactless Power Transfer System For Equipment Moving Along The Rail

The traditional power supplies for equipment moving along the rail use to be the cable or the drag chain,but the cable is easily to be wended and the drag chain is easily embed into the groove.Magnetic-field contactless power transfer(MCPT)is a good way to solve the problem when it is used as the power supply because the transmitting side and receiving side are out of contact and the wended cable can be avoided.But the equivalent resistance of the equipment is changing significantly when the motor starts up from static,so it is important to keep the output voltage stationary.This paper introduces the background and research status at home and abroad regarding to the contactless power transfer system which is used for the equipment moving along the rail.This paper introduces the basic structure of the system and analysises the reason that caused the instability of the output voltage.High-frequency inverter is studied in this paper.Two different kinds of high-frequency inverter are made up.For one of them,chip UC3875 and IR2110 are used which make the frequency of this inverter can be adjusted.However,the output power of this inverter is not high enough and the stability is not good where the frequency may change for long-tome running.For another inverter,chip UC3875 and HCPL-3120 are used and frequency division technology by crystal oscillator is taken.The inverter works stablely and the output power of it is up to several kW.This paper researches the compensation structure of the system.This paper analysises the relationship between the resistance and output voltage in the SS,SP,PS,PP topology and proposed a new compensation method that the LCL compensation is used at the primary side and capacitor series compensation(LCL-C compensation)is used at the secondary side.This paper derives and analysises the topology in detail and draw the conclusion that the output voltage has no relationship with the resistance at the secondary side in this compensation method.Coupling mechanism is studied in this paper.Several kinds of coupling mechanism which is usual in traditional CPT system are analysised.For equipment moving along the rail,a new coupling coil that the transmitting coil and receiving coil are face to face is designed.This kind of coupling coil makes the mutual inductor and voupling efficient a high value as well as unchangeable.An index,output-voltage dropped ratio,is prosed to measure the smoothness of the output,which means the value of the output voltage dropping as the resistance changes at the receiving side.Simulation and experiment are done to verify the validity of the compensation method and the coupling mechanism.The LTSPICE software which is based on nodal voltage equation is used to simulate the topology proposed in this paper which demonstrates that the output-voltage dropped ratio of the system is small when the resistance at the receiving side changes much.A prototype is built and 8 points on the transmitting coil are used for thr experiment.The result shows that the power supply for equipmen moving along the rail based on MCPT is able to drive the moto to lift up object whose mass is up to 1 ton.What's more,the output voltage is up to 2kW and the efficiency is more than 80% while the output-voltage dropped ratio is 13%.