Modeling and Control of a Boost Chopper Linked to AC Drive System for Hybrid Electric Vehicles

A boost chopper can link dc battery system and ac drive system to increase the overall efficiency of electric propulsion system in hybrid electric vehicles. Its criterion for the variable voltage command is typically maximum-torque-perampere operation of the ac machine to minimize its copper loss as much as possible. The switching frequency of a boost chopper is generally much higher than that of the three-phase inverter and the simulation of whole drive system including a boost chopper might be very slow if it is implemented in pulse-width-modulation level. This work discusses modeling of a boost chopper for digital control in the viewpoint of its linked motor drive system as a torque source in hybrid electric vehicles. This work takes advantage of SimPowerSystems for Simulink® to model the boost chopper. The battery model is assumed to be an ideal voltage source. Command generation and tracking feature of a dc-link voltage controller and estimation feature of the load current observer are also discussed. Simulation and test results show characteristics of the voltage controller.