Highly dynamic DC-voltage control by means of a bidirectional three phase voltage source inverter

In this paper a modulation strategy for an active rectifier is discussed. The rectifier is equipped with bi-directional switches to allow full control of the energy flow. This modulation strategy is based on a carrier signal whilst the switching frequency remains variable within a certain range. The switching frequency is dependent on the input value for the inverter output voltage. This modulation strategy allows easy set-up of the output voltage in the full range of the positive and negative rectified input voltage. This also allows the direct use energy storage systems with flexible voltages such as batteries. Due to the flexible switching frequency this modulation scheme allows a reduction of switching processes depending on the working point while the switching frequency remains based on the underlying PWM signal. The implementation of this strategy is illustrated in this paper as well as simulation results which demonstrate the variance in the switching frequency.