| Abstract |
Modern mass transit vehicles with propulsion system operating in the megawatt range and designed for line voltages of 1500 V DC are being equipped with GTO - PWM inverters today. These propulsion systems are capable of returning surplus power to the line. If the line is not receptive, this power is consumed by a GTO brake chopper plus resistor bank during braking. The subway in South Korea dispenses with such a brake chopper. Consequently the hitherto conventional circuitry is simplified, and cost as well as weight savings are obtained. The essential characteristics of the overall system remain unaffected thanks to skillful control of the PWM inverter and appropriately selective actuation of a protective thyristor. Protection of the system is guaranteed at all times. The particular characteristics of the PWM inverter system are described. Details are given on what the requirements are for the line and vehicle in order to realize the PWM inverter without a brake chopper, how specific components
have to be designed, and how the PWM inverter can be protected reliably. |
