DC-link capacitor reduction of a controlled rectifier supplying N inverter-motor drive systems by compensating the load variations

This paper deals with the compensations of the load variations in the control of DC-link voltage of the cascade of one rectifier-N inverter motor drive systems. The objective is to reduce the capacitance of the DC-link capacitors without affecting the stability of the DC-voltage control; so, the rectifier controllers should anticipate the load variation of the N inverter-motor drive systems. This is achieved by introducing compensating structures in the rectifier controllers; then, the DC-link voltage becomes almost insensitive to the load variations. This makes possible to design independently the controllers of the controlled rectifier from those of the inverter-motor assemblies. The presented simulation results validate the efficiency of the proposed methods.