Energy savings through regenerative braking using retrofit converters

This paper explores the benefits and feasibility of retrofitting existing phase controlled DC motor drives in the Queensland Rail coal transport system with PWM rectifier technology. The major benefits of this would be, the replacement of the dynamic brake with a regenerative system and unity power factor operation with a high quality input current waveshape. Test results indicate that very significant energy savings are possible if regenerative braking is introduced. The paper also surveys two standard PWM rectifier topologies suitable for this service. These two topologies are modelled and simulated using the dynamic systems simulation package “SIMULINK”