Time ratio regulation—A new inverter design technique

Silicon controlled rectifiers and time-ratio regulation techniques have been combined in a new power supply to provide increased reliability in railroad-radio service. Because of unusual environmental conditions, railroad locomotive and caboose radio equipment has been plagued with a high failure rate. These conditions include a wide variation in supply voltages, transient voltage surges, vibration, shock and temperature extremes. This paper describes two-way radio equipment that has been designed specifically for greater reliability in service on locomotives and cabooses. In the power supply, silicon controlled rectifiers are used in a new full-wave circuit in which both the pulse width and repetition rate of the stepped waveform are changed in order to maintain constant output voltages. Choke input filters are used to smooth the rectified secondary voltages and produce time-averaged values of the pulses. Design considerations and performance data are discussed. This design demonstrates the advantages of applying time-ratio regulation and controlled rectifier inverter techniques to railroad vehicular-communications power supplies. These techniques can be extended to D.C. to D.C. power supplies for other applications.