Modelling and simulation of controlled bi-directional power electronic converters in a DC energy distribution line with AC grid- and motor-side active filtering

The paper deals with the modelling and simulation of the bi-directional power flow through different type of power electronic converters connected to a DC-energy distribution line, which is supplied from the AC grid by means a square-wave rectifier with active current filtering at unity power factor. The DC line is supplying more vector controlled AC drives, like PWM voltage-source inverter-fed field oriented medium power induction motor and PM synchronous motor drives. There is connected also a high power induction motor drive fed by a tandem hybrid frequency converter containing of a high power current-source inverter for energy transfer and a low power voltage-source one for active filtering of the motor currents. The two DC-links of the component inverters are coupled by means of a two quadrant DC chopper. The modeling of the power electronic converters is based on circuit techniques, according to a similar method like the quadripole theory and not on circuit-oriented simulation concept. The simulation structures are containing blocks with two inputs and two outputs, one for the current and one for the voltage on each part of the quadripole. Each converter is consisting of a current-model- and a voltage-model-based block, which are coupled together by means of the commutation- or PWM-logic signals. The PWM converters (inverter, rectifier and active filter) are controlled with current feedback modulation at constant switching frequency. The square-wave rectifier and the DC-link chopper have “reverse” model versus the PWM converters, concerning the inputs and outputs with respect to the energy flow. The simulations were made in MATLAB-Simulink environment. The simulation structures built in MATLAB/Simulink are suitable for easy implementation of the motor and converter control structues due to the connection between the simulation environment and the hardware platform by means of dSPACE controller board.