Stabilization of DC Bus Voltage Using an Active Front-End Rectifier under Conditions of Power-Supply Unbalance

A controller structure is proposed featuring automatic tuning of the direct channel parameters in a dc bus voltage control loop, which is implemented using a three-phase active rectifier supplied by an unbalanced three-phase power source. The controller structure compensates for the influence of the nonstationary gain of the plant in the direct channel of the voltage control loop, thereby ensuring the desired system response to control signals and disturbances. The proposed controller structure enables the plant in the voltage control loop to be considered stationary and allows its parameters to be calculated based on previously established synthesis methods applicable to the symmetrical case, thereby simplifying the design process. A comparison of the dc bus voltage stabilization quality with and without automatic tuning of the voltage control loop parameters based on simulation modeling in MATLAB Simulink have shown that the proposed controller with automatic tuning significantly reduces the ripple component level in the dc bus voltage, both in the steady-state operation mode and during dynamic changes of the supplying three-phase voltage. It has also been found that maintaining a specified amplitude of the ripple component in the dc bus voltage can be achieved with a significantly smaller dc link capacitance of the active rectifier