Research On Uninterrupted Power Supply Technology For The Auxiliary System Of Electrical Locomotives

Auxiliary power system is an indispensable part of the train, providing power to traction controlling system, traction cooling system, lighting system, air condition, electronic network equipment and control system etc. Auxiliary system powered by auxiliary winding of traction transformer will be outage when train passing neutral section and control system is powered by battery at this time. This dissertation is based on the research of uninterrupted power supply technology of the auxiliary system when train passing neutral section.Uninterrupted power supply of auxiliary power system powered by auxiliary winding of traction transformer is irrealizable now and problems are studied. Failure reasons why previous solutions cannot be realized are analyzed. Vehicle-mounted auto-passing neutral section is widely used in China electric railway, its operation logic is ayalyzed. Control objectives of uninterrupted power supply technology are proposed, which are No overvoltage, No overcurrent and uninterrupted power supply. As route of energy coupled transfer, degree of coupling of each winding at traction transformer is very crucial. Impedance voltages of traction transformer are measured and degree of coupling of each winding, especially traction winding and auxiliary winding, is analyzed. Energy flow path to auxiliary system at neutral section is studied and indicated that control strategies of traction 4QC and auxiliary 4QC are the core technologies. Uninterrupted power supply technology of auxiliary system is proposed and uninterrupted power supply is achieved by adjusting control strategies of traction 4QC and auxiliary 4QC. Overvoltage and over current phenomenons will not happen during the whole process. Principle analysis, simulation verification and experimental verifications are finished and results indicate that the proposed technology is valid and reliable.Control technology of 4QC rectifier is one of the core technologies. Some control strategies are studied and a novel control strategy is proposed. The proposed synchronous roating reference frame PI regulator(SRFPI) is suitable for PWM rectifier and not only high-performance of zero-error tracking at fundamental frequency but also widening banwith nearby the fundamental frequency are both achieved. In consideration of frequency range of power grid, evaluataion criterion of performance of zero-error tracking for single-phase PWM rectifier is proposed. Based on this criterion, the proposed SRFPI possess outstanding performance than PR current regulator and qussi-PR current regulator.Smooth working of the auxiliary system is one of the control objectives of the proposed uninterrupted power supply technology. Quasi-direct power control strategy for single-phase PWM rectifier is proposed. By this quasi-direct power control, grid side active and reactive power can be independently and accurately controlled. By introducing the closed-loop of grid voltage, grid voltage fluctuation can be dilution by inner current loop. The proposed quasi-direct power control enhanced the anti-disturbance of the DC voltage of auxiliary converter.Dead time of ground auto-passing neutral section based electronic switch is shorted to 50ms, but uninterrupted power supply of auxiliary still can not be realized.Ground auto-passing neutral section is the second way to achieving uninterrupted power supply of the auxiliary system. A novel ground auto-passing neutral section technology is proposed. Circuit topology which includes Transformer and electronic switch are adopted in the proposed technology. The technical proposal can lessen quantity of the electronic switch and reduce difficulties of the designing of equalization circuit and trigger circuit. Trigger circuit is designed to guarantee the reliability. Dead time of the proposed technology is analyzed. The results show that 4QC can affect the magnetic flux of the traction transformer at dead time. To prevent the flux saturation of the traction transformer, design standard of the dead time is proposed. Aimming at dead time of ground auto-passing neutral section based electronic switch, uninterrupted power supply of auxiliary is studied and the proposed uninterrupted power supply technology is also applicable.