A Controllable 45-kW Current Source for DC Machines

A new type of dc converter for the drive and control of a 45-kW traction motor in single quadrant operation with an efficiency of 96 percent is presented. An improvement of the converter´s reliability is due to the natural termination of thyristor currents, the positive confinement of the maximum momentary current and voltage stresses in the components below preset levels, and the low power dissipation in these components, supported by a definite protection philosophy. The high converter efficiency is attained at full power operation with an internal frequency of 10 kHz. The input impedance maintains its resistive character for all conditions of operation. The output port is characterized as a voltage-limited current source. Test data of an experimental model conclude the presentation of the converter´s functional philosophy.