Matlab Simulink Bidirectional Converter Design for Regenerative Braking System In Electrical Vehicles.

I need a help for my project about Matlab Simulink Bidirectional Converter Design for Regenerative Braking System In Electrical Vehicles. I have a model but this model does not work properly. I need correction on it. It has bidirectional converter. I meet a problem with the cascade bidirectional converter. This converter should boost when the motor torque is greater than zero to accelerate the vehicle while buck when the motor torque is less than zero the regenerate the electricity.